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  • Articles  (137,236)
  • Oxford University Press  (84,264)
  • MDPI Publishing  (52,519)
  • PANGAEA
  • 2020-2024  (523)
  • 2015-2019  (136,713)
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  • 1
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    Fabric controls fault stability in serpentinite gouges (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-09
    Description: Serpentinites are polymineralic rocks distributed almost ubiquitously across the globe in active tectonic regions. Magnetite-rich serpentinites are found in the low-strain domains of serpen- tinite shear zones, which act as potential sites of nucleation of unstable slip. To assess the potential of earthquake nucleation in these materials, we investigate the link between me- chanical properties and fabric of these rocks through a suite of laboratory shear experiments. Our experiments were done at room temperature and cover a range of normal stress and slip velocity from 25 to 100 MPa and 0.3 to 300 μm s −1 , respecti vel y. We show that magnetite-rich serpentinites are ideal materials since they display strong sensitivity to the loading rate and are susceptible to nucleation of unstable slip, especially at low forcing slip velocities. We also aim at the integration of mechanical and microstructural results to describe the underlying mechanisms that produce the macroscopic behaviour. We show that mineralogical composi- tion and mineral structure dictates the coexistence of two deformation mechanisms leading to stable and unstable slip. The weakness of phyllosilicates allows for creep during the interseis- mic phase of the laboratory seismic cycle while favouring the restoration of a load-bearing granular framework, responsible of the nucleation of unstable events. During dynamic slip, fault zone shear fabric determines the mode of slip, producing either asymmetric or Gaussian slip time functions for either fast or slow events. We report rate/state friction parameters and integrate our mechanical data with microstructural observations to shed light on the mech- anisms dictating the complexity of laborator y ear thquakes. We show that mineralogical and fabric heterogeneities control fault slip behaviour.
    Description: Published
    Description: 1778–1797
    Description: OST3 Vicino alla faglia
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    New constraints on the shear wave velocity structure of the Ivrea geophysical body from seismic ambient noise tomography (Ivrea-Verbano Zone, Alps) (2024)
    Oxford University Press
    Details
    Publication Date: 2024-01-19
    Description: We performed seismic ambient noise tomography to investigate the shallow crustal structure around the Ivrea geophysical body (IGB) in the Ivrea-Verbano Zone (IVZ). We achieved higher resolution with respect to previous tomographic works covering the Western Alps, by processing seismic data collected by both permanent and temporary seismic networks (61 broad-band seismic stations in total). This included IvreaArray, a temporary, passive seismic experiment designed to investigate the IVZ crustal structure. Starting from continuous seismic ambient noise recordings, we measured and inverted the dispersion of the group velocity of surface Rayleigh waves (fundamental mode) in the period range 4–25 s. We obtained a new, 3-D vS model of the IVZ crust via the stochastic neighbourhood algorithm (NA), with the highest resolution between 3 to 40 km depth. The fast and shallow shear wave velocity anomaly associated with the IGB presents velocities of 3.6 km s−1 directly at the surface, in remarkable agreement with the location of the exposed lower-to-middle crustal and mantle outcrops. This suggests a continuity between the surface geological observations and the subsurface geophysical anomalies. The fast IGB structure reaches vS of 4 km s−1 at 20–25 km depth, at the boundary between the European and Adriatic tectonic plates, and in correspondence with the earlier identified Moho jump in the same area. The interpretation of a very shallow reaching IGB is further supported by the comparison of our new results with recent geophysical investigations, based on receiver functions and gravity anomaly data. By combining the new geophysical constraints and the geological observations at the surface, we provide a new structural interpretation of the IGB, which features lower crustal and mantle rocks at upper crustal depths. The comparison of the obtained vS values with the physical properties from laboratory analysis of local rock samples suggests that the bulk of the IGB consists of a combination of mantle peridotite, ultramafic and lower crustal rocks, bound in a heterogeneous structure. These new findings, based on vS tomography, corroborate the recent interpretation for which the Balmuccia peridotite outcrops are continuously linked to the IGB structure beneath. The new outcomes contribute to a multidisciplinary framework for the interpretation of the forthcoming results of the scientific drilling project DIVE. DIVE aims at probing the lower continental crust and its transition to the mantle, with two ongoing and one future boreholes (down to 4 km depth) in the IVZ area, providing new, complementary information on rock structure and composition across scales. In this framework, we constrain the upper crustal IGB geometries and lithology based on new evidence for vS, connecting prior crustal knowledge to recent active seismic investigations.
    Description: Published
    Description: 1089–1105
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Implications for the geometry of plate boundaries in NE Asia based on the geodetic analysis of the 2020Mw 6.4 Koryak event (2024)
    Oxford University Press
    Details
    Publication Date: 2024-01-23
    Description: On the 9th of January 2020, an Mw 6.4 strike-slip earthquake took place north of the Asian margin of the Bering Sea. The earthquake occurred within the known reverse-right-lateral active fault zone, called Khatyrka–Vyvenka, which transverses the Koryak Highland from SE to NW and is thought to be a surface manifestation of the Asian portion of either the Bering plate boundary or the northern edge of the Alaskan stream. No other strong earthquake has ever been recorded in this remote uninhabited area and the few existing seismic stations provide poor quality earthquake locations.We adopt SAR interferometry (InSAR) technique to define an improved location of the Koryak 2020 earthquake and constrain the seismic source. The analysis of the 2020 event revealed a previously unknown active fault of left-lateral kinematics that is possibly hidden and strikes NWtransversely to the Khatyrka–Vyvenka fault zone. Although several mechanisms could account for left-lateral kinematics of this fault, we propose that the structure is part of a more extended NW fault structure, that formed in pre-neotectonic times and has played a role of a pre-existing rheological discontinuity. This revived NW structure together with a similar structure located easterly, so far aseismic, make the plate/stream boundary segmented, step-like in plan view. The step-like boundary geometry may be the result of internal transform deformation of a rigid plate, but it is better explained by deflections of the Alaskan stream edge at local crustal asperities, which are pre-Cenozoic terrains.
    Description: Published
    Description: 1412–1421
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: Plate motion ; Radar interferometry ; Seismic cycle ; Asia
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Moment magnitude for earthquakes in the Etna volcano area (2024)
    Oxford University Press
    Details
    Publication Date: 2024-03-19
    Description: Accurate quantification of seismic activity in volcanic regions is an important asset for im- proving hazard and risk assessment. This is especially true for densely populated areas, as in the case of Etna volcano (Southern Italy). There, the volcanic hazard is amplified by the seismic risk of acti ve faults, especiall y on the eastern flank of the volcano. In such a context, it is common to rely on moment magnitude ( M W ) to characterize seismicity and monitor the energy released during an eruption. In this study, we calculate the moment-based magnitude ( M W ) for selected seismic data sets, using different approaches in distinct magnitude ranges to cover the widest possible range of magnitude that characterizes Etna’s seismicity . Specifically , we computed the M W from a data set of moment tensor solutions of earthquakes that occurred in the magnitude range 3.4 ≤M L ≤4.8 during 2005–2020; we created a data set of seismic moment and associated M W for earthquakes 1.0 ≤M L 〈 3.4 obtained by analysing source spectra; we fine-tuned two relationships, for shallow and deep earthquakes, to obtain M W from response spectra. Finally, we calibrated a specific relationship between M W and M L for the Etna area earthquakes in the range 1.0 ≤M L ≤4.8. All the empirical relationships obtained in this study can be applied in real-time analysis of the seismicity to provide fast and robust information on the released seismic energy.
    Description: INGV-DPC 2012- 2021 agreement; B2 DPC-INGV 2019-2021 project; IMPACT Department strategic project ; ‘Project PE0000005–RETURN (NRRP)
    Description: Published
    Description: 2520-2534
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: Earthquak e source observations ; Earthquake hazards ; Time series analysis ; Full moment tensor
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    A statistical framework for detection of b-value anomalies in Italy (2024)
    Oxford University Press
    Details
    Publication Date: 2024-03-12
    Description: This study presents a new robust statistical framework, in which to measure relative differences, or deviations from a hypothetical reference value, of Gutenberg-Richter b-value. Moreover, it applies this method to recent seismicity in Italy, to find possible changes of earthquake magnitude distribution in time and space. The method uses bootstrap techniques, which have no prior assumptions about the distribution of data, keeping their basic features. Excluding Central Italy, no significative b-value variation is found, revealing that the frequency-magnitude distribution exponent is substantially stable or that data are not able to reveal hidden variations. Considering the small size of examined magnitude samples, we cannot definitively decide if the higher b-values in Central Italy, consistently founded by all applied tests, have a physical origin or result from a statistical bias. In any case, they indicate short-lived excursions which have a temporary nature and, therefore, cannot be associated solely to spatial variations in tectonic framework. Both the methodological issues and the results of the application to seismicity in Italy show that a correct assessing of b-value changes requests appropriate statistics, that accurately quantify the low accuracy and precision of b-value estimation for small magnitude samples.
    Description: Published
    Description: 729–740
    Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Source mechanisms and induced seismicity in the Val d'Agri Basin (Italy) (2024)
    Oxford University Press
    Details
    Publication Date: 2024-03-12
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: We present the results from a fully unconstrained moment tensor inversion of induced seismic events in a complex and high seismic hazard region (Val d’Agri basin, Southern Italy). The study area hosts two well-documented cases of induced microseismicity linked to (i) a wastewater injection well of a giant oilfield (the largest in onshore Europe), and (ii) severe seasonal level changes of an artificial lake. In order to gather information on the non-doublecouple components of the source and to better understand the rupture mechanisms, we analyse seismic events recorded during daily injection tests in the disposal well. The computed moment tensors have significant non-double-couple components that correlate with the well-head injection pressure. The injection parameters strongly influence the rupture mechanism that can be interpreted as due to the opening/closing of a fracture network inside a fault zone of a pre-existing thrust fault. For the case of the reservoir-induced seismicity, no direct correlations are observed with the loading/unloading of the reservoir.
    Description: Published
    Description: 1617–1627
    Description: OST3 Vicino alla faglia
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    High frequency attenuation of S waves in alluvial deposits of the central Po Plain (northern Italy) (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-03
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: Estimation of local seismic response plays a key role in assessing local seismic hazard and particularly in the design of shaking scenarios. Modelling local seismic response involves knowing of the shear wave velocity (Vs) and quality factor (Qs) profiles for the site in question. The many techniques that have been developed to assess Vs in surface deposits produce reliable measurements of Vs , but these rarely correspond to direct measurements of Qs . The latter is often considered through damping measures from laboratory tests on small-scale soil samples, which can provide information primarily on intrinsic attenuation, neglecting the contribution of scattering effects. In this paper, using seismic recordings obtained at the surface and in boreholes at 100 m depth, we estimate an average value of Qs of some characteristic alluvial deposits of the Po Plain (northern Italy). Data come from a microseismic network which sampled an almost uniform lithology in the central Po Plain and consisted of three surface and four borehole stations with an interstation distance of about 2 km. The average value of Qs of the shallowest 100 m of the sedimentary strata, Qs100, is estimated by considering: (1) the high-frequency attenuation of seismic waves due to propagation through the corresponding stratigraphy and (2) the interference between incident and surface-reflected waves observed at borehole stations. We parametrize the first through k0_100, the difference between the values of the spectral decay parameter kappa (k) estimated at the surface and at the boreholes depth, respectively. We use the second in order to compute Vs100, the time-averaged Vs referred to the uppermost 100 m stratigraphy. We obtain: k0_100 = (11 ± 3) ms, Vs100 = (309 ± 11) m s −1 and Qs100 = 31 ± 10. At the surface, the estimated values of the site-specific kappa, k0, are found to range from 75 to 79 ms. As expected, these results are in good agreement with studies performed in other sites characterized by sandy or clayey lithologies, and can be usefully used in site response analysis at sites where the rigidity is mainly controlled by lithostatic pressure.
    Description: Comune di Minerbio (grant: “Sperimentazione ILG Minerbio”; grant number: 0913.010).
    Description: Published
    Description: 2075–2094
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: Earthquake ground motions ; Seismic attenuation ; Site effects ; Wave propagation ; Wave scattering and diffraction ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Comparison between alarm-based and probability-based earthquake forecasting methods (2024)
    Oxford University Press
    Details
    Publication Date: 2024-05-09
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: In a recent work, we applied the every earthquake a precursor according to scale (EEPAS) probabilistic model to the pseudo-prospective forecasting of shallow earthquakes with magni- tude M 5.0 in the Italian region. We compared the forecasting performance of EEPAS with that of the epidemic type aftershock sequences (ETAS) forecasting model, using the most recent consistency tests developed within the collaboratory for the study of earthquake predictabil- ity (CSEP). The application of such models for the forecasting of Italian target earthquakes seems to show peculiar characteristics for each of them. In particular, the ETAS model showed higher performance for short-term forecasting, in contrast, the EEPAS model showed higher forecasting performance for the medium/long-term. In this work, we compare the performance of EEPAS and ETAS models with that obtained by a deterministic model based on the occur- rence of strong foreshocks (FORE model) using an alarm-based approach. We apply the two rate-based models (ETAS and EEPAS) estimating the best probability threshold above which we issue an alarm. The model parameters and probability thresholds for issuing the alarms are calibrated on a learning data set from 1990 to 2011 during which 27 target earthquakes have occurred within the analysis region. The pseudo-prospective forecasting performance is as- sessed on a validation data set from 2012 to 2021, which also comprises 27 target earthquakes. Tests to assess the forecasting capability demonstrate that, even if all models outperform a purely random method, which trivially forecast earthquake proportionally to the space–time occupied by alarms, the EEPAS model exhibits lower forecasting performance than ETAS and FORE models. In addition, the relative performance comparison of the three models demonstrates that the forecasting capability of the FORE model appears slightly better than ETAS, but the difference is not statistically significant as it remains within the uncertainty level. However, truly prospective tests are necessary to validate such results, ideally using new testing procedures allowing the analysis of alarm-based models, not yet available within the CSEP.
    Description: Published
    Description: 1541–1551
    Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto
    Description: JCR Journal
    Keywords: Computational seismology ; Earthquake interaction, forecasting and prediction ; Statistical seismology ; Comparison betwee earthquake forecasting methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Low-strength shear zone in the western Makran subduction zone, southeastern Iran: insights from a receiver function analysis (2024)
    Oxford University Press
    Details
    Publication Date: 2024-05-09
    Description: To understand the seismic hazard of a subduction zone, it is necessary to know the geometry, location and mechanical characteristics of the interplate boundary below which an oceanic plate is thrust downward. By considering the azimuthal dependence of converted P-to-S (Ps) amplitudes in receiver functions, we have detected the interplate boundary in the Makran subduction zone, revealing significant seismic anisotropy at the base of the accretionary wedge above the slab before it bends down beneath the Jaz Murian basin. This anisotropic feature aligns with a zone of reduced seismic velocity and a high primary/secondary wave velocity ratio (Vp/Vs), as documented in previous studies. The presence of this low-velocity highly anisotropic layer at the base of the accretionary wedge, likely representing a low-strength shear zone, could possibly explain the unusually wide accretionary wedge in Makran. Additionally, it may impact the location and width of the locked zone along the interplate boundary.
    Description: Iranian National Science Foundation (INSF)
    Description: Published
    Description: 64-74
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Keywords: Earthquake hazards, Seismic anisotropy, Crustal structure, Subduction zone processes ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Application of the EEPAS earthquake forecasting model to Italy (2024)
    Oxford University Press
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    Publication Date: 2024-05-09
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: The Every Earthquake a Precursor According to Scale (EEPAS) forecasting model is a space– time point-process model based on the precursory scale increase (ψ ) phenomenon and associated predictive scaling relations. It has been previously applied to New Zealand, Cal- ifornia and Japan earthquakes with target magnitude thresholds varying from about 5–7. In all previous application, computations were done using the computer code implemented in Fortran language by the model authors. In this work, we applied it to Italy using a suite of computing codes completely rewritten in Matlab. We first compared the two software codes to ensure the convergence and adequate coincidence between the estimated model parameters for a simple region capable of being analysed by both software codes. Then, using the rewritten codes, we optimized the parameters for a different and more complex polygon of analysis using the Homogenized Instrumental Seismic Catalogue data from 1990 to 2011. We then perform a pseudo-prospective forecasting experiment of Italian earthquakes from 2012 to 2021 with Mw ≥ 5.0 and compare the forecasting skill of EEPAS with those obtained by other time in- dependent (Spatially Uniform Poisson, Spatially Variable Poisson and PPE: Proximity to Past Earthquakes) and time dependent [Epidemic Type Aftershock Sequence (ETAS)] forecasting models using the information gain per active cell. The preference goes to the ETAS model for short time intervals (3 months) and to the EEPAS model for longer time intervals (6 months to 10 yr).
    Description: Published
    Description: 1681–1700
    Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto
    Description: JCR Journal
    Keywords: Computational seismology ; Earthquake interaction ; forecasting and prediction ; Statistical seismology ; Earthquake forecasting
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
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    Hydrological and volcano-related gravity signals at Mt. Somma–Vesuvius from ∼20 yr of time-lapse gravity monitoring: implications for volcano quiescence (2024)
    Oxford University Press
    Details
    Publication Date: 2024-05-27
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: We report on about 20 yr of relative gravity measurements, acquired on Mt. Somma–Vesuvius volcano in order to investigate the hydrological and volcano-tectonic processes controlling the present-day activity of the volcano. The retrieved long-term field of time gravity change (2003–2022) shows a pattern essentially related to the subsidence, which have affected the central part of the volcano, as detected by the permanent GNSS network and InSAR data. After reducing the observations for the effect of vertical deformation, no significant residuals are found, indicating no significant mass accumulation or loss within the volcanic system. In the north-western sector of the study area, at the border of the volcano edifice, however, significant residual positive gravity changes are detected which are associated to ground-water rebound after years of intense exploitation of the aquifers. On the seasonal timescale, we find that stations within the caldera rim are affected by the seasonal hydrological effects, while the gravity stations at the base of the Vesuvius show a less clear correlation. Furthermore, within the caldera rim a multiyear gravity transient is detected with an increase phase lasting about 4 yr followed by a slower decrease phase. Analysis of rain data seem to exclude a hydrological origin, hence, we hypothesize a deeper source related to the geothermal activity, which can be present even if the volcano is in a quiescent state. We infer the depth and volume of the source by inverting the spatial pattern of the gravity field at the peak of the transient. A volume of fluids of 9.5 × 107 m3 with density of 1000 kg m−3 at 2.3 km depth is capable to fit reasonably well the observations. To explain the gravity transient, simple synthetic models are produced, that simulate the ascent of fluids from a deep reservoir up to the depth of 2.3 km and a successive diffusion within the carbonate aquifer hosting the geothermal system. The whole process appears to not significantly affect the seismicity rate and the deformation of the volcano. This study demonstrates the importance of a 4-D gravity monitoring of a volcano to understand its complex gravity signals that cover different spatial and temporal scales. Discriminating the different contributions that mix up in the observed gravity changes, in particular those due to hydrologic/anthropogenic activities form those due to the geothermal dynamics, is fundamental for a complete and reliable evaluation of the volcano state.
    Description: Published
    Description: 1565–1580
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
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  • 12
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    Anaerobic respiration in a boreal wetland and surrounding habitats, across a hydrological transect. (2024)
    PANGAEA
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    Publication Date: 2024-04-11
    Description: This dataset reports measurements from a laboratory incubation of soils sourced from a boreal peatland and surrounding habitats (Siikaneva Bog, Finland). In August 2021, soil cores were collected from three habitat zones: a well-drained upland forest, an intermediate margin ecotone, and a Sphagnum moss bog. The cores from each habitat were taken from surface to approximately 50cm below surface using an Eijelkamp peat corer and subdivided by soil horizon. The samples were then incubated anaerobically for 140 days in three temperature treatment groups (0, 4, 20°C). Subsamples of the incubations headspace (250 µL) were measured on a gas chromatograph (7890A, Agilent Technologies, USA) with flame ionization detection (FID) for CO2 and CH4 concentrations. The rate of respiration from the samples were calculated per gram carbon and per gram soil as described in the method of Robertson., et al. (1999) and reported here, along with other relevant parameters.
    Language: English
    Type: info:eu-repo/semantics/workingPaper
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  • 13
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    Data collection of the sediment core MR16-09_PC03 in the Southeast Pacific (2024)
    PANGAEA
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    Publication Date: 2024-04-08
    Type: info:eu-repo/semantics/workingPaper
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  • 14
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    Cross-site comparisons of dryland ecosystem response to climate change in the US long-term ecological research network (2023)
    Oxford University Press
    Details
    Publication Date: 2023-02-25
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hudson, A. R., Peters, D. P. C., Blair, J. M., Childers, D. L., Doran, P. T., Geil, K., Gooseff, M., Gross, K. L., Haddad, N. M., Pastore, M. A., Rudgers, J. A., Sala, O., Seabloom, E. W., & Shaver, G. Cross-site comparisons of dryland ecosystem response to climate change in the US long-term ecological research network. Bioscience, 72(9), (2022): 889–907, https://doi.org/10.1093/biosci/biab134.
    Description: Long-term observations and experiments in diverse drylands reveal how ecosystems and services are responding to climate change. To develop generalities about climate change impacts at dryland sites, we compared broadscale patterns in climate and synthesized primary production responses among the eight terrestrial, nonforested sites of the United States Long-Term Ecological Research (US LTER) Network located in temperate (Southwest and Midwest) and polar (Arctic and Antarctic) regions. All sites experienced warming in recent decades, whereas drought varied regionally with multidecadal phases. Multiple years of wet or dry conditions had larger effects than single years on primary production. Droughts, floods, and wildfires altered resource availability and restructured plant communities, with greater impacts on primary production than warming alone. During severe regional droughts, air pollution from wildfire and dust events peaked. Studies at US LTER drylands over more than 40 years demonstrate reciprocal links and feedbacks among dryland ecosystems, climate-driven disturbance events, and climate change.
    Description: Funding was provided by the USDA-ARS SCINet Big Data Project (grant no. 0500–00093–001–00-D), and the National Science Foundation US LTER Program to New Mexico State University for the Jornada Basin (grant no. DEB 20–25166), Kansas State University for the Konza Prairie (grant no. DEB 2025849), the Kellogg Biological Station (grant no. DEB 1832042), Cedar Creek Ecosystem Science Reserve (grants no. DEB-1234162 and no. DEB-1831944), ARC (grant no. DEB-1637459), MCM (grant no. OPP-1637708), CAP (grant no. DEB-1832016), and SEV (grant no. DEB-1655499). Support was also provided by the Minnesota Supercomputer Institute and the University of Minnesota, Michigan State University AgBioResearch.
    Repository Name: Woods Hole Open Access Server
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  • 15
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    Genesis of Oceanic Oxide Gabbros and Gabbronorites During Reactive Melt Migration at Transform Walls (Doldrums Megatransform System; 7–8°N Mid-Atlantic Ridge) (2023)
    Oxford University Press
    Details
    Publication Date: 2023-01-25
    Description: The Doldrums Megatransform System (~7–8°N, Mid-Atlantic Ridge) shows a complex architecture including four intra-transform ridge segments bounded by five active transform faults. Lower crustal rocks are exposed along the Doldrums and Vernadsky transform walls that bound the northernmost intra-transform ridge segment. The recovered gabbros are characterized by variably evolved chemical compositions, ranging from olivine gabbros to gabbronorites and oxide gabbros, and lack the most primitive gabbroic endmembers (troctolites, dunites). Notably, the numerous recovered gabbronorites show up to 20 vol. % of coarse-grained orthopyroxene. Although covariations in mineral and bulk-rock chemical compositions of the olivine and oxide gabbros define trends of crystallization from a common parental melt, the gabbronorites show elevated light over heavy rare earth elements (LREE/HREE) ratios in both bulk-rock and mineral compositions. These features are not consistent with a petrological evolution driven solely by fractional crystallization, which cannot produce the preferential enrichments in highly incompatible elements documented in the orthopyroxene-bearing lithologies. We suggest that gabbronorites crystallized from evolved melts percolating and partly assimilating a pre-existing olivine gabbro matrix. Saturation in orthopyroxene and selective enrichments in LREE relative to M-HREE are both triggered by an increase in assimilated crystal mass, which ranges from negligible in the oxide-gabbros to abundant in the gabbronorites. This melt–rock reaction process has been related to lateral melt migration beneath ridge-transform intersections, where variably evolved melts injected from the peripheral parts of the melting region towards the transform zone may interact with a gabbroic crystal mush to form abundant oxide-bearing gabbronoritic associations.
    Description: Published
    Description: egac086
    Description: 3A. Geofisica marina e osservazioni multiparametriche a fondo mare
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
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    Mechanism of the 2017 M-w 6.3 Pasni earthquake and its significance for future major earthquakes in the eastern Makran (2023)
    Oxford University Press
    Details
    Publication Date: 2023-02-17
    Description: Author Posting. © The Author(s), 2022. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 231(2),(2022): 1434–1445, https://doi.org/10.1093/gji/ggac257.
    Description: Makran subduction zone is very active with ∼38 mm yr−1 convergence rate and has experienced great earthquakes in the past. The latest great earthquake of 1945 Mw 8.1 event also triggered a large tsunami and led to ∼4000 casualties. However, due to incomplete historical seismicity records and poor modern instrumentation, earthquake mechanism, co-seismic slip and tsunami characteristics in Makran remain unclear. On 2017 February 17, an Mw 6.3 earthquake rattled offshore Pasni of Pakistan in the eastern Makran, marking the largest event after the 1945 Mw 8.1 earthquake with good geodetic and geophysical data coverage. We use a combination of seismicity, multibeam bathymetry, seismic profile, InSAR measurements and tide-gauge observation to investigate the seismogenic structure, co-seismic deformation, tsunami characteristics of this event and its implication for future major earthquakes. Our results indicate that (1) the earthquake occurred on the shallow-dipping (3°–4°) megathrust; (2) the megathrust co-seismically slipped 15 cm and caused ∼2–4 cm ground subsidence and uplift at Pasni; (3) our tsunami modelling reproduces the observed 5-cm-high small tsunami waveforms. The Pasni earthquake rupture largely overlaps the 1945 slip patch and disturbs the west and east megathrust segments that have not ruptured yet at least since 1765. With such stress perturbation and possible stress evolution effect from the 1945 earthquake, the unruptured patches may fail in the future. This study calls for more preparedness in mitigating earthquake and associated hazards in the eastern Makran.
    Description: his study is financially supported by the National Natural Science Foundation of China (Nos. 42076059, 41890813, 41976066 and 41976064), the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (No. GML2019ZD0205), Chinese Academy of Sciences (Nos. Y4SL021001, QYZDY-SSW-DQC005, 131551KYSB20200021, ISEE2021PY03, 133244KYSB20180029 and E1SL3C02), Guangdong Basic and Applied Basic Research Foundation (No. 2021B1515020098) and China–Pakistan Joint Research Centre on Earth Sciences.
    Keywords: Tsunamis ; Earthquake dynamics ; Earthquake hazards ; Seismicity and tectonics ; Subduction zone processes
    Repository Name: Woods Hole Open Access Server
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  • 17
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    Strong ground-motion prediction equations from induced earthquakes in St. Gallen geothermal field, Switzerland (2023)
    Oxford University Press
    Details
    Publication Date: 2023-03-15
    Description: Ground shaking, whether it is due to natural or induced earthquakes, has always been a matter of concern since it correlates with structural/non-structural damage and can culminate in human anxiety. Industrial activities such as water injection, gas sequestration and waste fluid disposals, promote induced seismicity and consequent ground shaking that can hinder ongoing activities. Therefore, keeping in mind the importance of timely evaluation of a seismic hazard and its mitigation for societal benefits, the present study proposes specifically designed ground-motion prediction equations (GMPEs) from induced earthquakes in the St. Gallen geothermal area, Switzerland. The data analysed in this study consist of 343 earthquakes with magnitude −1.17 ≤ ML, corr ≤ 3.5 and hypocentral distance between 4 and 15 km. The proposed study is one of the first to incorporate ground motions from negative magnitude earthquakes for the development of GMPEs. The GMPEs are inferred with a two-phase approach. In the first phase, a reference model is obtained by considering the effect of source and medium properties on the ground motion. In the second phase the final model is obtained by including a site/station effect. The comparison between the GMPEs obtained in the present study with GMPEs developed for the other induced seismicity environments highlights a mismatch that is ascribed to differences in regional seismic environment and local site conditions of the respective regions. This suggests that, when dealing with induced earthquakes, GMPEs specific for the study should be inferred and used for both monitoring purposes and seismic hazard analyses.
    Description: Published
    Description: 820–832
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    The ground deformation of the south-eastern flank of Mount Etna monitored by GNSS and SAR interferometry from 2016 to 2019 (2023)
    Oxford University Press
    Details
    Publication Date: 2023-12-27
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: The south-eastern sector of the Mount Etna, Italy, is characterized by numerous active faults, in particular the Belpasso–Ognina lineament, the Tremestieri–San Gregorio–Acitrezza fault, the Trecastagni fault and the Fiandaca–Nizzeti fault including the Timpe Fault System. Their activity is the result of both volcanism and tectonics. Here, we analyse the ground deformation occurred from 2016 to 2019 across those active faults by using the GNSS data acquired at 22 permanent stations and 35 campaign points observed by the Etna Observatory (INGV) and by the University of Catania. We also use the time-series of line of sight displacement of permanent scatterers SENTINEL-1 A-DInSAR obtained by using the P-SBAS tool of the ESA GEP-TEP (Geohazards Thematic Exploitation Platform) service. We discriminate the contributions of the regional tectonic strain, the inflations, the deflations of the volcano and the gravitational sliding in order to analyse the deformation along the faults of the south-eastern flank of Etna. The shallow and destructive Mw = 4.9 earthquake of 2018 December 26 occurred within the studied area two days after a dyke intrusion, that propagated beneath the centre of the volcano accompanied by a short eruption. Both GNSS and InSAR time-series document well those events and allow to investigate the post-seismic sliding across the faults of south-eastern flank. We analyse the slow slip events (SSE) that are observed in the GNSS and InSAR time-series in the vicinity of the Acitrezza fault. We quantify and discuss the tectonic origin of the Belpasso–Ognina lineament that we interpreted as a tear fault.
    Description: Published
    Description: 664–682
    Description: OST3 Vicino alla faglia
    Description: JCR Journal
    Keywords: Satellite geodesy ; Transient deformation ; Interferometry ; Fractures ; fault ; Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
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    Surface air temperature measured at the Argentinean–German Geodetic Observatory (AGGO), 2018-2021. (2023)
    PANGAEA
    Details
    Publication Date: 2023-08-25
    Description: Surface air temperature measurements obtained from different sensors are used to construct a unique time series with one minute time-interval. Apart from differences in design and environmental exposition, periods of missing data also exist in the data series of each sensor. A primary data set was selected in terms of quality and temporal extension. A combination of two different techniques is applied to complete this data set: one is based on the autocorrelation of the series and the other on measurements taken from other sensors. The resulting values constitute a complete series of surface air temperature at AGGO.
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  • 20
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    Relative humidity measured at the Argentinean–German Geodetic Observatory (AGGO), 2018-2021 (2023)
    PANGAEA
    Details
    Publication Date: 2023-09-18
    Description: Surface air temperature measurements obtained from different sensors are used to construct a unique time series with one minute time-interval. Apart from differences in design and environmental exposition, periods of missing data also exist in the data series of each sensor. A primary data set was selected in terms of quality and temporal extension. A combination of two different techniques is applied to complete this data set: one is based on the autocorrelation of the series and the other on measurements taken from other sensors. The resulting values constitute a complete series of surface air temperature at AGGO.
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  • 21
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    Time series of water samples and stable water isotope measurements collected at Puente Lavalle (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-24
    Description: This dataset contain stable isotope values for water samples collected ~weekly from the Rio Bermejo at the Lavalle bridge (-25.6513, -60.1277) from March 2016 to February 2018. Water samples were filtered to 0.2 micron using a custom filtration device. We measured d2H and d18O on a Picarro L-2140i Cavity Ring-Down Spectrometer at the GFZ Potsdam. Measurements were made in duplicate, normalized to the Vienna Standard Mean Ocean Water (VSMOW), and analytical uncertainty is reported as one standard deviation from the mean. River discharge was measured at the El Colorado gauging station, which is ~100 km down slope from the sampling location.
    Language: English
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  • 22
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    Lake Uddelermeer: Holocene Geochemistry data (alkanes, GDGt, delta-Deuterium, CNHS) (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-24
    Description: This dataset provides the geochemistry data for the Holocene sediment sequence retrieved from Lake Uddelermeer (The Netherlands) in 2012. Additionally, alkane concentrations for a set of modern leaf samples are provided. Concentrations of fossil alkanes, GDGTs as well as elemental (C, N, S, H) and compound-specific delta Deuterium measurements are presented against both depth (cm) and age (cal yr. BP). A total of 59 samples were analysed. Modern leaf alkane concentrations are presented as concentrations, 10 samples were analysed. The geochemical data provides information about regional vegetation change as well as changes in effective precipitation. It was produced to inform on the age and duration of major environmental transitions during the middle and late Holocene. Cores were retrieved from the lake using a 3-m long handheld piston corer deployed from a floating coring platform during field work in April and May 2012. Samples were obtained from splits of the core and processed in the laboratory of the University of Amsterdam (the Netherlands) using standard protocols (CNHS, alkane concentrations), the laboratory of Utrecht University (the Netherlands; GDGT concentrations) and at GFZ Potsdam (Germany; delta Deuterium). Name of the Campaign: UDD Event Label: UDD-E Method: Uwitec piston corer Latitude: 52.24652778 Longitude: 5.76097222 Elevation: 24m asl Date/Time of event: 2012-05-01T14:00:00 Further information about event: Lake sediment sequence retrieved using a 60 mm piston corer deployed from a floating platform.
    Language: English
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  • 23
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    Dissolved concentrations of major elements and water isotopes for water samples from the Rio Bermejo mainstem, tributaries, spring-fed channels, and groundwater wells (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-24
    Description: Water samples were filtered to 0.2 micron prior to measurement. Samples for cation analysis were acidified in the field to pH 〈 2 using 6N HNO3. Cation concentrations were measured with a Varian 720 inductively coupled plasma optical emission spectrometer (ICP-OES) at the GFZ Helmholtz Laboratory for the Geochemistry of the Earth Surface (HELGES), using SLRS-5 (Saint-Laurent River Surface, National Research Council - Conseil National de Recherches Canada) and USGS M212 and USGS T187 as external standards. We corrected for instrument drift by measuring an internal standard (GFZ-RW1) every 10 samples and we determined measurement uncertainty using calibration curve uncertainty. Anion concentrations were measured with a Dionex ICS1100 Ion Chromatograph, using USGS standards M206 and M212 as external standards for quality control, with uncertainty determined from triplicate analysis. We corrected cation concentrations for cyclic salt inputs following Bickle et al. (2005, doi:10.1016/j.gca.2004.11.019).
    Language: English
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  • 24
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    Bulk stable isotopes of composite sediment core NC_08/01 (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Description: Presented are analytical data from lacustrine sediment cores, retrieved from Lake Nam Co (Tibetan Plateau). The sediment core is a composite of one gravity core, taken with a Rumohr-Meischner gravity corer (63 mm diameter) and a piston core, retrieved using an uwitec piston coring system (http://www.uwitec.at; 90 mm diameter). The composite core labelled 〈NC 08/01〉 comprises a total length of 10.378 m. The cores were obtained at N 30.737417, E 090.790333 at a water depth of 93 m on 2008-09-15. The purpose of obtaining this sediment core was to establish a high-resolution record of climate (monsoonal) and environmental change using multiple proxy data. The dataset comprises analytical data based on sedimentological, inorganic geochemical, mineralogical and isotope-geochemical methods. Specifically: sediment water content & density; magnetic susceptibility; particel size data; quantitative inorganic geochemical data (ICP-OES aqua regia and HCL digestions); semi-quantitative XRF elemental data; carbon, nitrogen, sulfur contents; qualitative mineralogical data; bulk sediment stable carbon and oxygen isotope data.
    Language: English
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  • 25
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    Standardized element data of sediment core EN18208 from Lake Sysy-Kyuele (Yakutia, Russia) (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized X-ray fluorescence line scanning (XRF)-based element data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). The downcore elemental composition was measured using an AVAATECH x-ray fluorescence core scanner at Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) in Berlin, Spandau.
    Language: English
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  • 26
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    Standardized radiocarbon data of sediment core EN18208 from Lake Ilirney (Chukotka, Russia) (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized radiocarbon and OSL age data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Radiocarbon data have been analysed from bulk sediment samples in Bremerhaven at the MICADAS laboratory. Optically stimulated luminescence (OSL) dating was performed at the Royal Holloway Luminescence Laboratory using a Risø TL/OSL-DA-15 automated dating system.
    Language: English
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  • 27
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    Dharamjali speleothem trace elements and stable isotopes (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Description: A 25-cm long predominantly aragonite stalagmite was collected November 2, 2005 from Dharamjali Cave (29.5°N, 80.2°E) in the central Himalayas. This dataset contains stable isotope, trace element, XRF, U/Th dating, and dripwater data. The age model spans 4.2 to 2.3 ka BP, and the dataset records seasonal shifts in hydroclimate from 4.2 to 3.1 ka BP. Using the DHAR-1A half of the speleothem, 750 samples were milled at 100–300 µm resolution for stable isotope analysis (δ18O and δ13C) and analyzed at GFZ Potsdam. Further high-resolution stable isotope analysis at the University of Cambridge included 876 samples from the bottom 4 cm of the mirroring slab DHAR-1B, covering c. 4.2–3.6 ka BP. The δ44/40Ca measurements were made on 60 aragonite samples of aragonite and 1 calcite sample milled between 4.2 and 2.8 ka BP. The elemental composition of DHAR-1B was determined first with an Avaatech XRF scanner at the University of Cambridge, and later using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) at the University of Waikato. U-series dating was performed at Caltech on 22 samples. Twelve U-series ages (between 2.55 and 4.14 ka BP) were used to construct the age models, using ensembles of 2000 Monte Carlo simulations for each proxy using the MATLAB-based COPRA script (Breitenbach et al., 2012, https://doi.org/10.5194/cp-8-1765-2012).
    Language: English
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  • 28
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    Standardized grain size data of sediment core EN18208 from Lake Sysy-Kyuele (Yakutia, Russia) (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized grain size element data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Grain-size was measured using a Malvern Mastersizer 3000 laser diffraction particle analyser.
    Language: English
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  • 29
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    Standardized mineral data of sediment core EN18208 from Lake Ilirney (Chukotka, Russia) (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized mineral data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Bulk mineralogy was analysed by (x-ray diffractometry (XRD) using a (PHILIPS, Netherlands) PW1820 goniometer.
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  • 30
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    Standardized organic geochemistry data of sediment core EN18208 from Lake Ilirney (Chukotka, Russia) (2023)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized radiocarbon and OSL age data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Water content and organic matter was analysed at AWI Potsdam. Dried and milled samples were analysed using a Vario EL III carbon-nitrogen-sulphur analyser. Organic carbon content was determined using a Vario MAX C analyser.
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    Metagenomic survey of the microbiome of ancient Siberian permafrost and modern Kamchatkan cryosols (2022)
    Oxford University Press
    In:  EPIC3microLife, Oxford University Press, 3(1), pp. 1-15, ISSN: 2633-6693
    Details
    Publication Date: 2024-01-30
    Description: In the context of global warming, the melting of arctic permafrost raises the threat of a re-emergence of microorganisms some of which were shown to remain viable in ancient frozen soils for up to half a million years. In order to evaluate this risk, it is of interest to acquire a better knowledge of the composition of the microbial communities found in this understudied environment. Here we present a metagenomics analysis of 12 soil samples from Russian Arctic and subarctic pristine areas: Chukotka, Yakutia, and Kamchatka, including 9 permafrost samples collected at various depths. These large datasets (9.2 1011 total bp) were assembled (525,313 contigs 〉 5kb), their encoded protein contents predicted, then used to perform taxonomical assignments of bacterial, archaeal, and eukaryotic organisms, as well as DNA viruses. The various samples exhibited variable DNA contents and highly diverse taxonomic profiles showing no obvious relationship with their locations, depths or deposit ages. Bacteria represented the largely dominant DNA fraction (95%) in all samples, followed by archaea (3.2%), surprisingly little eukaryotes (0.5%), and viruses (0.4%). Although no common taxonomic pattern was identified, the samples shared unexpected high frequencies of β-lactamase genes, almost 0.9 copy/bacterial genome. In addition of known environmental threats, the particularly intense warming of the Arctic might thus enhance the spread of bacterial antibiotic resistances, today's major challenge in public health. β-lactamases were also observed at high frequency in other types of soils, suggesting their general role in the regulation of bacterial populations.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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    Literature synthesis data of surface energy fluxes and environmental drivers from Arctic vegetation and glacier sites (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset describes the data generated in a literature synthesis, covering 358 study sites on vegetation or glacier (〉=60°N latitude), which contained surface energy budget observations. The literature synthesis comprised 148 publications searched on the ISI Web of Science Core Collection.
    Language: English
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  • 33
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    Effects of a brackish water inflow on peat pore water variables and methane-cycling microbial community abundances in a freshwater rewetted coastal fen. (2022)
    PANGAEA
    Details
    Publication Date: 2023-02-09
    Description: The rewetting of peatlands is a promising measure to mitigate greenhouse gas (GHG) emissions by preventing the further mineralization of the peat soil through aeration. In coastal peatland, the rewetting with brackish water can increase the GHG mitigation potential by the introduction of sulfate, a terminal electron acceptor (TEA). Sulfate is known to lower the CH4 production and thus, its emission by favoring the growth of sulfate-reducers, which outcompete methanogens for substrate. The data contain porewater variables such as pH, electrical conductivity (EC) and sulfate, chloride, dissolved CO2 and CH4 concentrations, as well as absolute abundances of methane- and sulfate-cycling microbial communities. The data were collected in spring and autumn 2019 after a storm surge with brackish water inflow in January 2019. Field sampling was conducted in the nature reserve Heiligensee and Hütelmoor in North-East Germany, close to the Southern Baltic Sea coast. We took peat cores using a Russian peat corer in addition to pore water diffusion samplers and plastic liners (length: 60cm; inner diameter 10 cm) at four locations along a transect from further inland towards the Baltic Sea. We wanted to compare the soil and pore water geochemistry as well as the microbial communities after the brackish water inflow to the common freshwater rewetting state. Pore water was extracted using pore water suction samplers in the lab and environmental variables were quantified with an ICP. Microbial samples were sampled from the peat core using sterile equipment. We used quantitative polymerase chain reaction (qPCR) to characterize pools of DNA and cDNA targeting total and putatively active bacteria and archaea. qPCR was performed on key functional genes of methane production (mcrA), aerobic methane oxidation (pmoA) and sulfate reduction (dsrB) in addition to the 16S rRNA gene for the absolute abundance of total prokaryotes. Furthermore, we retrieved soil plugs to determine the concentrations and isotopic signatures of dissolved trace gases (CO2/DIC and CH4) in the pore water.
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    Varve thickness of lateglacial ICDP core 5017-1-A-44 (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset provides annually resolved microfacies data from ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition (ca. 14-13 ka BP). Sediments of the Lisan Formation were investigated between ~94.7 and 91.8 m sediment depth below lake floor (lithozone C2) by continuous thin section microscopy. Thin sections were prepared following the standard procedure by Brauer and Casanova (2001) that was adjusted for salty sediments. Thin section analyses were performed on overlapping large-scale thin sections using a Zeiss Axiolab pol microscope at magnifications of 50-400x. Microfacies analyses included varve counting and measurements of varve and sublayer thickness. The amount of varves in erosional gaps was interpolated and the position of mass flow deposits (MFD) is marked.
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  • 35
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    Physical properties of sea ice cores from L sites measured on leg 1 of the MOSAiC expedition (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.
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  • 36
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    n-Fatty acid composition per sediment mass in a rapidly eroding permafrost cliff (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Organic carbon (OC) stored in Arctic permafrost represents one of Earth’s largest and most vulnerable terrestrial carbon pools. Amplified climate warming across the Arctic results in widespread permafrost thaw. Permafrost deposits exposed at river cliffs and coasts are particularly susceptible to thawing processes. Accelerating erosion of terrestrial permafrost along shorelines leads to increased transfer of organic matter (OM) to nearshore waters. However, the amount of terrestrial permafrost carbon and nitrogen as well as the OM quality in these deposits are still poorly quantified. Here, we characterise the sources and the quality of OM supplied to the Lena River at a rapidly eroding permafrost river shoreline cliff in the eastern part of the delta (Sobo-Sise Island). Our multi-proxy approach captures bulk elemental, molecular geochemical and carbon isotopic analyses of late Pleistocene Yedoma permafrost and Holocene cover deposits, discontinuously spanning the last ~52 ka. We show that the ancient permafrost exposed in the Sobo-Sise cliff has a high organic carbon content (mean of about 5 wt%).We found that the OM quality, which we define as the intrinsic potential to further transformation, decomposition, and mineralization, is also high as inferred by the lipid biomarker inventory. The oldest sediments stem from Marine Isotope Stage (MIS) 3 interstadial deposits (dated to 52 to 28 cal kyr BP) and is overlaid by Last Glacial MIS 2 (dated to 28 to 15 cal ka BP) and Holocene MIS 1 (dated to 7–0 cal ka BP) deposits. The relatively high average chain length (ACL) index of n-alkanes along the cliff profile indicates a predominant contribution of vascular plants to the OM composition. The elevated ratio of iso and anteiso-branched FAs relative to long chain (C ≥ 20) n-FAs in the interstadial MIS 3 and the interglacial MIS 1 deposits, suggests stronger microbial activity and consequently higher input of bacterial biomass during these climatically warmer periods. The overall high carbon preference index (CPI) and higher plant fatty acid (HPFA) values as well as high C / N ratios point to a good quality of the preserved OM and thus to a high potential of the OM for decomposition upon thaw. A decrease of HPFA values downwards along the profile probably indicates a relatively stronger OM decomposition in the oldest (MIS 3) deposits of the cliff.
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  • 37
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    Physical properties of sea ice cores from site MCS_FYI measured on legs 1 to 3 of the MOSAiC expedition (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.
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  • 38
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    Alkane, fatty acid, total (organic) carbon and nitrogen distribution in ancient permafrost deposits at the Batagay Megaslump, East Siberia (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: These datasets describe sediment samples taken from the Batagay megaslump, located in Yana Uplands in northeastern Siberia. Most sediment samples were taken from the slump headwall (B19-P1) by rapelling down on a rope from the slump surface and taking samples with a hole saw (diameter 55 mm, 40 mm deep) mounted on a handheld power drill. A second profile (B19-02) of the lowest part of the slump headwall was sampled (~100 m south) using a hammer and axe from the slump floor. Two permafrost sediment blocks (B19-03 and B19-04) at the slump bottom that had fallen from the headwall were sampled using a chainsaw. Finally, a baidzherakh (thermokarst mound; B19-05) in the north of the slump was sampled using a hammer and axe. The samples cover 5 stratigraphical units: 1. lower ice complex, 2. lower sand unit, 3. woody layer, 4. upper ice complex, 5. Holocene cover.
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  • 39
    facet.materialart.
    Unknown
    n-Fatty acid composition per total organic carbon in a rapidly eroding permafrost cliff (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Organic carbon (OC) stored in Arctic permafrost represents one of Earth’s largest and most vulnerable terrestrial carbon pools. Amplified climate warming across the Arctic results in widespread permafrost thaw. Permafrost deposits exposed at river cliffs and coasts are particularly susceptible to thawing processes. Accelerating erosion of terrestrial permafrost along shorelines leads to increased transfer of organic matter (OM) to nearshore waters. However, the amount of terrestrial permafrost carbon and nitrogen as well as the OM quality in these deposits are still poorly quantified. Here, we characterise the sources and the quality of OM supplied to the Lena River at a rapidly eroding permafrost river shoreline cliff in the eastern part of the delta (Sobo-Sise Island). Our multi-proxy approach captures bulk elemental, molecular geochemical and carbon isotopic analyses of late Pleistocene Yedoma permafrost and Holocene cover deposits, discontinuously spanning the last ~52 ka. We show that the ancient permafrost exposed in the Sobo-Sise cliff has a high organic carbon content (mean of about 5 wt%).We found that the OM quality, which we define as the intrinsic potential to further transformation, decomposition, and mineralization, is also high as inferred by the lipid biomarker inventory. The oldest sediments stem from Marine Isotope Stage (MIS) 3 interstadial deposits (dated to 52 to 28 cal kyr BP) and is overlaid by Last Glacial MIS 2 (dated to 28 to 15 cal ka BP) and Holocene MIS 1 (dated to 7–0 cal ka BP) deposits. The relatively high average chain length (ACL) index of n-alkanes along the cliff profile indicates a predominant contribution of vascular plants to the OM composition. The elevated ratio of iso and anteiso-branched FAs relative to long chain (C ≥ 20) n-FAs in the interstadial MIS 3 and the interglacial MIS 1 deposits, suggests stronger microbial activity and consequently higher input of bacterial biomass during these climatically warmer periods. The overall high carbon preference index (CPI) and higher plant fatty acid (HPFA) values as well as high C / N ratios point to a good quality of the preserved OM and thus to a high potential of the OM for decomposition upon thaw. A decrease of HPFA values downwards along the profile probably indicates a relatively stronger OM decomposition in the oldest (MIS 3) deposits of the cliff.
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  • 40
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    Alkane distribution in ancient permafrost deposits at the Batagay Megaslump, East Siberia (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Language: English
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  • 41
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    Physical properties of sea ice cores from site MCS-SYI measured on legs 1 to 3 of the MOSAiC expedition (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.
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  • 42
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    Rock and paleomagnetic data from two sediment cores from the Black Sea for the past 30 ka (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Rock magnetic and paleomagnetic results covering the past 30 ka were constructed from two sediment cores MSM33_856-1 (MSM33-55-1) and MSM33_855-1 (54-3) from the Black Sea. After the Mediterranean Sea water ingression, finely laminated organic-rich sapropelic sediments and coccolith oozes were deposited in the Black Sea since about 8.3 ka. Relict magnetic minerals in the Black Sea sarpoples are ferrous hemoilmenite, Fe-Mn and Fe-Cr spinels, and magnetite inclusions. In sediments deposited between about 14 and 8 ka, greigite and pyrite were formed in sediments because of the seawater penetration from overlying sediments after the seawater ingression. Before ~14 ka, the Black Sea sediments are dominated by detrital (titano-)magnetite minerals and the sporadically formed greigite which has SIRM/kLF ratios 〉 10 kAm-2. By comparison with detrital (titano-)magnetite samples between 20-30 ka, we found that relict magnetic mineral samples between 0-8.3 ka have similar behavior in recording the geomagnetic field. Moreover, the geomagnetic field variations reconstructed from the Black Sea sapropels are comparable with other validated regional datasets for the past 8.3 ka. The natural remanent magnetization (NRM) and the anhysteretic remanent magnetization (ARM) were measured with a 2G Enterprises 755 SRM (cryogenic) long-core magnetometer equipped with a sample holder for eight discrete samples at a separation of 20 cm. The magnetometer's in-line tri-axial alternating field (AF) demagnetizer was used to demagnetize the NRM and ARM of the samples. The NRM was measured after application of AF peak amplitudes of 0, 5, 10, 15, 20, 30, 40, 50, 65, 80, and 100 mT. Directions of the characteristic remanent magnetization (ChRM) were determined by principle component analysis (PCA) according to Kirschvink (1980). The error range of the ChRM is given as the maximum angular deviation (MAD). The ARM was imparted along the samples' z-axis with a static field of 0.05 mT and an AF field of 100 mT. Demagnetization then was performed in steps of 0, 10, 20, 30, 40, 50, 65, and 80 mT. The median destructive field of the ARM (MDFARM) was determined to estimate the coercivity of the sediments. The slope of NRM versus ARM of common demagnetization steps was used to determine the relative paleointensity (RPI). In most cases, demagnetization steps from 20 to 65 mT were used to determine the RPI.
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  • 43
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    TICON-td: Third-degree tidal constants based on GESLA sea-level records from globally distributed tide gauges (data) (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset provides data for four third-degree tidal constituents used in the publication of Sulzbach et al (2022). The tidal constituents provided are the 3M1, 3M3, 3N2 and 3L2 for 134 globally distributed stations. The tide information, such as the nodal modulations of these tides, are taken from Table 1 and Table S2 of Ray (2020). These tidal constants are estimated using the GESLA dataset (Woodworth et al 2014) following the approach presented in Piccioni et al (2019). This record is an add-on to the full TICON dataset (https://doi.org/10.1594/PANGAEA.896587), using exactly the same data format and pre-processing. These steps include using tide gauge data that contains at least ten years of continuous data. Further, the dataset is restricted to only contain open ocean tide gauges by limiting it to a mean surrounding depth of tide gauges to be deeper than 500 meters in a 2-degree radius and excluding stations not native to the ocean domain of the employed tidal model TiME. Duplicate and closely neighbouring tide gauges, found within a 0.2-degree radius, are also removed from the dataset. This resulted in the availability of the four tidal constants for 134 tide gauges. The results are stored in one tab-separated text/ASCII file with 13 columns: 1. Latitude of the tide gauge station 2. Longitude of the tide gauge station 3. Constituent name 4. Amplitude (in cm) 5. Phase (in degrees) 6. Standard deviation of the amplitude (in cm) 7. Standard deviation of the phase (in degrees) 8. Percentage of missing observations 9. Total number of observations analyzed 10. Length of the maximum temporal gap found in the time series in days 11. Date of the first observation 12. Date of the last observation 13. Code that corresponds to the original source of the record TICON is a useful and easy-to-handle data set for tide model validation and allows the users to select the records according to the different criteria most suitable for their purposes. The options span from the choice of a geographical region to the use of single constituents or time periods.
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  • 44
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    Total (organic) carbon and nitrogen content in ancient permafrost deposits at the Batagay Megaslump, East Siberia (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Language: English
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  • 45
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    Rock and paleomagnetic results of sediment core MSM33\_856-1 over the past 30 ka (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Language: English
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  • 46
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    Microfacies data and age model from the International Continental Scientific Drilling Program (ICDP) Dead Sea core and the Masada outcrop (southwestern shore of the Dead Sea) (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: These datasets provide sedimentological data partly at annual resolution and an age model for the lateglacial part of (1) the ICDP sediment core 5017-1-A retrieved from the deep northern Dead Sea basin in 2010/11, and (2) for the Masada outcrop located at the southwestern shore of the Dead Sea sampled in 2018. The here investigated two sediment sections cover the last glacial-interglacial transition (ca. 17-11.5 ka BP) in the hydroclimatically sensitive Levant, when the water level of Lake Lisan – the precursor of the Dead Sea – dropped dramatically from its glacial high-stand to the Holocene low levels. Here, we analyze the interval between the last two gypsum units – the Upper Gypsum Unit (UGU) and the Additional Gypsum Unit (AGU) – which were also used to correlate the two sites. In the ICDP core this section is located between ~101 and 88.5 m sediment depth below lake floor and at Masada it encompasses the uppermost ~3.8 m sediments of the Lisan Formation, which form the terminal deposit at this site. Due to the lake level decline, the complete transition into the Holocene is only recorded in the ICDP core, while sedimentation at Masada terminates earlier. The microfacies was investigated by continuous thin section microscopy, while additional macroscopic information is provided from over- and underlying sediment sections. A revised chronology using age modelling in OxCal (Ramsey 2008; Ramsey 2009; Ramsey and Lee 2013) was developed for the ICDP core and a floating varve chronology was constructed at Masada. Using these new microfacies data from marginal (Masada) and deep-water (ICDP core) sediments, the hydroclimatic variability during the final stage of Lake Lisan can be reconstructed, which could provide important insights into the development of human sedentism in the region at this time.
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  • 47
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    Physical properties of sea ice cores from site BGC3 measured on legs 1 to 3 of the MOSAiC expedition (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.
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  • 48
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    Fatty acid distribution in ancient permafrost deposits at the Batagay Megaslump, East Siberia (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
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  • 49
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    Varve thickness of lateglacial ICDP core 5017-1-A (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset provides annually resolved microfacies data from ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition (ca. 17-11.5 ka BP). Sediments of the Lisan Formation were investigated between ~101 and 88.5 m sediment depth below lake floor by continuous thin section microscopy, while additional macroscopic information is provided from core catchers, as well as from over- and underlying sediment sections. Thin sections were prepared following the standard procedure by Brauer and Casanova (2001) that was adjusted for salty sediments. Thin section analyses were performed on overlapping large-scale thin sections using a Zeiss Axiolab pol microscope at magnifications of 50-400x. Microfacies analyses included varve counting and measurements of varve and sublayer thickness.
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  • 50
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    Harmonized in-situ observations of surface energy fluxes and environmental drivers at 64 Arctic vegetation and glacier sites - Metadata (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset contains metadata information about surface energy budget components measured at 64 tundra and glacier sites 〉60° N across the Arctic. This information was taken from the open-access repositories FLUXNET, Ameriflux, AON, GC-Net and PROMICE. The contained datasets are associated with the publication vegetation type as an important predictor of the Arctic Summer Land Surface Energy Budget by Oehri et al. 2022, and intended to support research of surface energy budgets and their relationship with environmental conditions, in particular vegetation characteristics across the terrestrial Arctic.
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  • 51
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    Age model of lateglacial ICDP core 5017-1-A (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset provides the results from Bayesian age depth modelling in OxCal for ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition between ~101 and 88.5 m sediment depth below lake floor (ca. 17-11.5 ka BP). The model was performed in OxCal v.4.4 using a P_Sequence (1,1,C(-2,2)) (Ramsey 2008; Ramsey 2009; Ramsey and Lee 2013) and includes three tephrochronological ages from Neugebauer et al. (2021) and three radiocarbon ages from Kitagawa et al. (2017).
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  • 52
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    Harmonized in-situ observations of surface energy fluxes and environmental drivers at 64 Arctic vegetation and glacier sites - Surface energy budget componenent data (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset comprises harmonized, standardized and aggregated in-situ observations of surface energy budget components measured at 64 sites on vegetated and glaciated sites north of 60° latitude, in the time period from 1994 till 2021. The surface energy budget components include net radiation, sensible heat flux, latent heat flux, ground heat flux, net shortwave radiation, net longwave radiation, surface temperature and albedo, which were aggregated to daily mean, minimum and maximum values from hourly and half-hourly measurements. Data were retrieved from the monitoring networks FLUXNET, AmeriFlux, AON, GC-Net and PROMICE.
    Language: English
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    Physical properties of sea ice cores from site BGC2 measured on legs 1 to 3 of the MOSAiC expedition (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.
    Language: English
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  • 54
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    Physical properties of sea ice cores for biogeochemistry studies measured on legs 1 to 3 of the MOSAiC expedition (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.
    Language: English
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  • 55
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    Biogeochemical parameters of thawed sediments underneath a Yedoma and Alas thermokarst lake in Eastern Siberia, version 2 (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset describes two 17 m long sediment cores taken from beneath two thermokarst lakes in the Yukechi Alas, Central Yakutia, Russia. The first core was taken from below an Alas thermokarst lake (YU-L7; 61.76397°N, 130.46442°E) and the second core below and Yedoma lake (YU-L15; 61.76086°N, 130.47466°E). The dataset presents biogeochemical and biomarker parameters of sediment cores YU-L7 and YU-L15. Biogeochemical analyses include total carbon (TC) content, total organic carbon (TOC) content, total nitrogen (TN) content. Biomarker parameters include the n-alkane concentration, average chain length (ACL), carbon preference index (CPI), brGDGT concentration, archaeol concentration and the isoGDGT-0 concentration. The n-alkanes were measured in the aliphatic fraction by gas chromatography-mass spectromety using a Trace GC Ultra coupled to a DSQ MS. The branched and isoprenoid glycerol dialkyl glycerol tetraethers, as well as the dialkyl glycerol diether lipid (archaeol) were measured in the NSO fraction using a Shimadzu LC-10AD high-performance liquid chromatograph coupled to a Finnigan TSQ 7000 mass spectrometer via an atmospheric pressure chemical ionization interface. The pH soil is the sediment pH which was assessed by adding 6.12 mL of 0.01 M CaCl~2~ to ~2.5 g dried sediment and measuring with a Multilab 540 (WTW) at 20°C.
    Language: English
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  • 56
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    Physical properties of sea ice cores from site BGC1 measured on legs 1 to 3 of the MOSAiC expedition (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.
    Language: English
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  • 57
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    Harmonized in-situ observations of surface energy fluxes and environmental drivers at 64 Arctic vegetation and glacier sites (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In-situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. Therefore, we here provide four datasets comprising: 1. Harmonized, standardized and aggregated in situ observations of SEB components at 64 vegetated and glaciated sites north of 60° latitude, in the time period 1994-2021 2. A description of all study sites and associated environmental conditions, including the vegetation types, which correspond to the classification of the Circumpolar Arctic Vegetation Map (CAVM, Raynolds et al. 2019). 3. Data generated in a literature synthesis from 358 study sites on vegetation or glacier (〉=60°N latitude) covered by 148 publications. 4. Metadata, including data contributor information and measurement heights of variables associated with Oehri et al. 2022.
    Language: English
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    Lithology of lateglacial ICDP core 5017-1-A (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset provides lithological data from ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition (ca. 17-11.5 ka BP). The microfacies of the Lisan Formation was investigated between ~101 and 88.5 m sediment depth below lake floor by continuous thin section microscopy, while additional macroscopic information is provided from core catchers, as well as from over- and underlying sediment sections. Thin sections were prepared following the standard procedure by Brauer and Casanova (2001) that was adjusted for salty sediments. Thin section analyses were performed on overlapping large-scale thin sections using a Zeiss Axiolab pol microscope at magnifications of 50-400x.
    Language: English
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  • 59
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    Rock and paleomagnetic results of sediment core MSM33\_855-1 over the past 30 ka (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Language: English
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  • 60
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    Lateral and vertical carbon fluxes from the polygonal tundra in the Lena River Delta, Siberia (summer 2014) (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset contains observations of water discharge rates and concentrations of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) from a polygonal tundra site in the Lena River Delta, Russia. This dataset also contains lateral carbon fluxes of DOC and DIC that were estimated from these observations. Additionally, this dataset contains vertical fluxes of carbon dioxide and methane from the same study site. All observations were recorded on Samoylov Island (N 72.377188, E 126.495144) in the summer of 2014. The abbreviations A1, A2 and B refer to three outflows on the island where the hydrological parameters were observed (A1: N 72.379991, E 126.480886; A2: N 72.380134, E 126.481433; B: N 72.381348, E 126.483482). All outflows were approximately 10 meters. More information can be found in https://doi.org/10.5194/bg-19-3863-2022.
    Language: English
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  • 61
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    Harmonized in-situ observations of surface energy fluxes and environmental drivers at 64 Arctic vegetation and glacier sites - Environmental conditions (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset describes the environmental conditions for 64 tundra and glacier sites (〉=60°N latitude) across the Arctic, for which in situ measurements of surface energy budget components were harmonized (see Oehri et al. 2022). These environmental conditions are (proxies of) potential drivers of SEB-components and could therefore be called SEB-drivers. The associated environmental conditions, include the vegetation types graminoid tundra, prostrate dwarf-shrub tundra, erect-shrub tundra, wetland complexes, barren complexes (≤ 40% horizontal plant cover), boreal peat bogs and glacier. These land surface types (apart from boreal peat bogs) correspond to the main classification units of the Circumpolar Arctic Vegetation Map (CAVM, Raynolds et al. 2019). For each site, additional climatic and biophysical variables are available, including cloud cover, snow cover duration, permafrost characteristics, climatic conditions and topographic conditions.
    Language: English
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    Marine ERT surveys acquired in the region of Tuktoyaktuk Island, Northwest Territories, Canada (2022)
    PANGAEA
    Details
    Publication Date: 2023-02-01
    Description: This dataset contains over 30 marine Electrical Resistivity Tomography (ERT) profiles taken in September 2021 around Tuktoyaktuk Island (NWT / Beaufort Sea, Canada). The measurements were part of the “Mackenzie Delta Permafrost Field Campaign” (mCan2021) within the “Modular Observation solutions for Earth Systems” (MOSES) program. The collected profiles consist of numerous adjacent vertical soundings in a (quasi-symmetric) reciprocal Wenner-Schlumberger array, using a floating cable towed behind a boat. GPS records along the electrode streamer were taken, enabling the improvement of pre- processing by excluding measurements for which the cable was curved and electrode positions deviated too widely. The aim of the study was to determine the depth of the submarine permafrost. Cleaned data is provided in csv format.
    Language: English
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  • 63
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    Permafrost related measurements in the Mackenzie Delta, Northwest Territories, Canada, from the MOSES field campaign in September 2021 (2022)
    PANGAEA
    Details
    Publication Date: 2023-02-01
    Description: This collection contains permafrost related measurements in the Mackenzie Delta, NWT, Canada from the MOSES (Modular Observation Solutions for Earth Systems) field campaign in September 2021. The field campaign was focused on three subaquatic sites: a small thermokarst lake along the ITH just south of Trail Valley Creek, "Lake 3", an elongated lake with known methane occurence in the outer Mackenzie Delta, "Swiss Cheese Lake", and north and south of Tuktoyaktuk Island. At "Swiss Cheese Lake", we measured methane and CO2 concentrations in surface water and in the air above the lake, lake bed temperatures and detailed bathymetry. At "Lake 3" we measured active layer thickness on the lake banks, lake bed temperatures, and detailed bathymetry, as well as an ERT survey to estimate the talik depth below the lake. North and south of Tuktoyaktuk Island, we measured active layer thickness and sea bed temperatures and did an extensive ERT survey to obtain the depth of the subsea permafrost table. An additional passive seismic survey was carried out and the data is available at https://doi.org/10.5880/GIPP.202199.1.
    Language: English
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  • 64
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    Lacustrine and amphibian ERT surveys acquired in the region of Inuvik, Northwest Territories, Canada (2022)
    PANGAEA
    Details
    Publication Date: 2023-02-01
    Description: This dataset contains seven Electrical Resistivity Tomography (ERT) profiles taken in September 2021 at “Lake 3”, a thermokarst lake near the Inuvik-Tuktoyaktuk-Highway (ITH), about 50 km north of Inuvik (NWT, Canada). The measurements were part of the “Mackenzie Delta Permafrost Field Campaign” (mCan2021) within the “Modular Observation solutions for Earth Systems” (MOSES) program. The collected profiles consist of numerous adjacent vertical soundings in a (quasi-symmetric) reciprocal Wenner-Schlumberger array. In addition to surveys on the lake, using a floating cable towed behind a boat, two “amphibian” profiles were taken. Starting as purely terrestrial surveys using metal spike electrodes, the cable was then moved towards the lake with some of the electrodes floating on the water surface, and some still on land. The aim of the study was to determine permafrost properties on the land, to detect a possible talik beneath the lake and to especially be able to infer the transition between the two below the shoreline.
    Language: English
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  • 65
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    Fault imaging at Mt Pollino (Italy) from relative location of microearthquakes (2021)
    Oxford University Press
    Details
    Publication Date: 2023-10-26
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2021. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: Relative location of microearthquakes that occurred at Mt Pollino (Italy) from 2011 to 2013 have been analyzed with the aim of a detailed imaging of the geometry of active faults. We identified 27 clusters composed of a number of earthquakes from 9 to 33, with local magnitude in the range 0.6–2.7. The relative location shows that the distribution of hypocentres in each cluster is characterized by extension from few tens of meters to at most 350 m. For each cluster the hypocentre distribution was fitted by a plane to infer the fault orientation, and results were compared with the fault plane solutions corresponding to the focal mechanism of earthquakes of the same cluster. The comparison shows a good agreement in most of the cases. The relative location analysis, generally applied to earthquakes with similar waveform, has been improved to permit also the relative location of earthquakes characterized by not similar signals. To achieve this purpose a modified procedure that overcome the condition of very similar waveforms has been applied to estimate the time delay between first pulses of the master events. The relative location of master events of all clusters shows a precise imaging of the relative position of all analysed sources and allows also to follow with high accuracy the evolution in time of the seismic swarm within the selected periods. The hypocentre position of master events and the nearly parallel fitting planes of any clusters suggest that most of the analyzed earthquakes were produced by different patches of the same fault. The final results depict a main fault plane characterized by NW–SE strike, dip of about 35–45° and depth between 4.5 and 6.5 km b.s.l. Focal mechanisms, used also to evaluate the local stress field, are mostly of normal type with few strike slip solutions for the shallowest events. This result is in good agreement with the local tectonic stress regime that is characterized by predominant NE–SW transtension, as inferred from structural, seismological and geophysical data.
    Description: Published
    Description: 637–648
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Persistence, memory, correlations, clustering, Spatial analysis, Crustal imaging, Earthquake source observations, Seismicity and tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Upper mantle deformation signatures of craton–orogen interaction in the Carpathian–Pannonian region from SKS anisotropy analysis (2021)
    Oxford University Press
    Details
    Publication Date: 2023-10-31
    Description: Since the Mesozoic, central and eastern European tectonics have been dominated by the closure of the Tethyan Ocean as the African and European plates collided. In the Miocene, the edge of the East European Craton and Moesian Platform were reworked in collision during the Carpathian orogeny and lithospheric extension formed the Pannonian Basin. To investigate the mantle deformation signatures associated with this complex collisional-extensional system, we carry out SKS splitting analysis at 123 broad-band seismic stations in the region. We compare our measurements with estimates of lithospheric thickness and recent seismic tomography models to test for correlation with mantle heterogeneities. Reviewing splitting delay times in light of xenolith measurements of anisotropy yields estimates of anisotropic layer thickness. Fast polarization directions are mostly NW–SE oriented across the seismically slow West Carpathians and Pannonian Basin and are independent of geological boundaries, absolute plate motion direction or an expected palaeo-slab roll-back path. Instead, they are systematically orthogonal to maximum stress directions, implying that the indenting Adria Plate, the leading deformational force in Central Europe, reset the upper-mantle mineral fabric in the past 5 Ma beneath the Pannonian Basin, overprinting the anisotropic signature of earlier tectonic events. Towards the east, fast polarization directions are perpendicular to steep gradients of lithospheric thickness and align along the edges of fast seismic anomalies beneath the Precambrian-aged Moesian Platform in the South Carpathians and the East European Craton, supporting the idea that craton roots exert a strong influence on the surrounding mantle flow. Within the Moesian Platform, SKS measurements become more variable with Fresnel zone arguments indicating a shallow fossil lithospheric source of anisotropy likely caused by older tectonic deformation frozen in the Precambrian. In the Southeast Carpathian corner, in the Vrancea Seismic Zone, a lithospheric fragment that sinks into the mantle is sandwiched between two slow anomalies, but smaller SKS delay times reveal weaker anisotropy occurs mainly to the NW side, consistent with asymmetric upwelling adjacent to a slab, slower mantle velocities and recent volcanism.
    Description: Published
    Description: 2105–2118
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Seismic anisotropy ; geodynamics ; Seismic anisotropy and geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Broad-band ground-motion simulation of 2016 Amatrice earthquake, Central Italy (2021)
    Oxford University Press
    Details
    Publication Date: 2023-11-21
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2021. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: On 24 August 2016 at 01:36 UTC a ML6.0 earthquake struck several villages in central Italy, among which Accumoli, Amatrice and Arquata del Tronto. The earthquake was recorded by about 350 seismic stations, causing 299 fatalities and damage with macroseismic intensities up to 11. The maximum acceleration was observed at Amatrice station (AMT) reaching 916 cm s–2 on E–W component, with epicentral distance of 15 km and Joyner and Boore distance to the fault surface (RJB) of less than a kilometre. Motivated by the high levels of observed ground motion and damage, we generate broad-band seismograms for engineering purposes by adopting a hybrid method. To infer the low frequency seismograms, we considered the kinematic slip model by Tinti et al . The high frequency seismograms were produced using a stochastic finite-fault model approach based on dynamic corner-frequency. Broadband synthetic time-series were therefore obtained by merging the low and high frequency seismograms. Simulated hybrid ground motions were compared both with the observed ground motions and the ground-motion prediction equations (GMPEs), to explore their performance and to retrieve the region-specific parameters endorsed for the simulations. In the near-fault area we observed that hybrid simulations have a higher capability to detect near source effects and to reproduce the source complexity than the use of GMPEs. Indeed, the general good consistency found between synthetic and observed ground motion (both in the time and frequency domain), suggests that the use of regional-specific source scaling and attenuation parameters together with the source complexity in hybrid simulations improves ground motion estimations. To include the site effect in stochastic simulations at selected stations, we tested the use of amplification curves derived from HVRSs (horizontal-to-vertical response spectra) and from HVSRs (horizontal-to-vertical spectral ratios) rather than the use of generic curves according to NTC18 Italian seismic design code. We generally found a further reduction of residuals between observed and simulated both in terms of time histories and spectra.
    Description: Published
    Description: 1753–1779
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Rapid Prediction of Earthquake Ground Shaking Intensity Using Raw Waveform Data and a Convolutional Neural Network (2021)
    Oxford University Press
    Details
    Publication Date: 2023-11-16
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2020. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved
    Description: This study describes a deep convolutional neural network (CNN) based technique for the prediction of intensity measurements (IMs) of ground shaking. The input data to the CNN model consists of multistation 3C broadband and accelerometric waveforms recorded during the 2016 Central Italy earthquake sequence for M $\ge$ 3.0. We find that the CNN is capable of predicting accurately the IMs at stations far from the epicenter and that have not yet recorded the maximum ground shaking when using a 10 s window starting at the earthquake origin time. The CNN IM predictions do not require previous knowledge of the earthquake source (location and magnitude). Comparison between the CNN model predictions and the predictions obtained with Bindi et al. (2011) GMPE (which require location and magnitude) has shown that the CNN model features similar error variance but smaller bias. Although the technique is not strictly designed for earthquake early warning, we found that it can provide useful estimates of ground motions within 15-20 sec after earthquake origin time depending on various setup elements (e.g., times for data transmission, computation, latencies). The technique has been tested on raw data without any initial data pre-selection in order to closely replicate real-time data streaming. When noise examples were included with the earthquake data, the CNN was found to be stable predicting accurately the ground shaking intensity corresponding to the noise amplitude.
    Description: Published
    Description: 1379–1389
    Description: 8T. Sismologia in tempo reale
    Description: JCR Journal
    Keywords: Physics - Geophysics; Physics - Geophysics ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Understanding seismic path biases and magmatic activity at Mount St Helens volcano before its 2004 eruption (2021)
    Oxford University Press
    Details
    Publication Date: 2023-11-16
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2020. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: In volcanoes, topography, shallow heterogeneity and even shallow morphology can substan- tially modify seismic coda signals. Coda waves are an essential tool to monitor eruption dynamics and model volcanic structures jointly and independently from velocity anomalies: it is thus fundamental to test their spatial sensitivity to seismic path effects. Here, we apply the Multiple Lapse Time Window Analysis (MLTWA) to measure the relative importance of scattering attenuation vs absorption at Mount St Helens volcano before its 2004 erup- tion. The results show the characteristic dominance of scattering attenuation in volcanoes at lower frequencies (3–6 Hz), while absorption is the primary attenuation mechanism at 12 and 18 Hz. Scattering attenuation is similar but seismic absorption is one order of magnitude lower than at open-conduit volcanoes, like Etna and Kilauea, a typical behaviour of a (rela- tively) cool magmatic plumbing system. Still, the seismic albedo (measuring the ratio between seismic energy emitted and received from the area) is anomalously high (0.95) at 3 Hz. A radiative-transfer forward model of far- and near-field envelopes confirms this is due to strong near-receiver scattering enhancing anomalous phases in the intermediate and late coda across the 1980 debris avalanche and central crater. Only above this frequency and in the far-field diffusion onsets at late lapse times. The scattering and absorption parameters derived from MLTWA are used as inputs to construct 2-D frequency-dependent bulk sensitivity kernels for the S-wave coda in the multiple-scattering (using the Energy Transport Equations—ETE) and diffusive (AD, independent of MLTWA results) regimes. At 12 Hz, high coda-attenuation anomalies characterize the eastern side of the volcano using both kernels, in spatial correla- tion with low-velocity anomalies from literature. At 3 Hz, the anomalous albedo, the forward modelling, and the results of the tomographic imaging confirm that shallow heterogeneity beneath the extended 1980 debris-avalanche and crater enhance anomalous intermediate and late coda phases, mapping shallow geological contrasts. We remark the effect this may have on coda-dependent source inversion and tomography, currently used across the world to image and monitor volcanoes. At Mount St Helens, higher frequencies and deep borehole data are necessary to reconstruct deep volcanic structures with coda waves.
    Description: Scottish Alliance for Geosciences Environment and Society and the Kleinman Grant for Volcano Research
    Description: Published
    Description: 169-188
    Description: 1T. Struttura della Terra
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 3IT. Calcolo scientifico
    Description: JCR Journal
    Keywords: NorthAmerica ; Wave scattering and diffraction. ; Codawaves ; Seismicattenuation ; Seismic tomography ; Volcano seismology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Methodology to identify the reference rock sites in regions of medium-to-high seismicity: an application in Central Italy (2021)
    Oxford University Press
    Details
    Publication Date: 2023-11-14
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2020. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: To evaluate the site response using both empirical approaches (e.g. standard spectral ratio, ground motion models (GMMs), generalized inversion techniques, etc.) and numerical 1-D/2-D analyses, the definition of the reference motion, that is the ground motion recorded at stations unaffected by site-effects due to topographic, stratigraphic or basin effects, is needed. The main objective of this work is to define a robust strategy to identify the seismic stations that can be considered as reference rock sites, using six proxies for the site response: three proxies are related to the analysis of geophysical and seismological data (the repeatable site term from the residual analysis, the resonance frequencies from horizontal-to-vertical spectral ratios on noise or earthquake signals, the average shear wave velocity in the first 30 m); the remaining ones concern geomorphological and installation features (outcropping rocks or stiff soils, flat topography and absence of interaction with structures). We introduce a weighting scheme to take into account the availability and the quality of the site information, as well as the fulfillment of the criterion associated to each proxy. We also introduce a hierarchical index, to take into account the relevance of the proposed proxies in the description of the site effects, and an acceptance threshold for reference rock sites identification. The procedure is applied on a very large data set, composed by accelerometric and velocimetric waveforms, recorded in Central Italy in the period 2008–2018. This data set is composed by more than 30 000 waveforms relative to 450 earthquakes in the magnitude range 3.2–6.5 and recorded by more than 450 stations. A total of 36 out of 133 candidate stations are identified as reference sites: the majority of them are installed on rock with flat topography, but this condition is not sufficient to guarantee the absence of amplifications, especially at high frequencies. Seismological analyses are necessary to exclude stations affected by resonances. We test the impact of using these sites by calibrating a GMMs. The results show that for reference rock sites the median predictions are reduced down to about 45 per cent at short periods in comparison to the generic rock motions.
    Description: Published
    Description: 2053–2067
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Arrival-angle effects on two-receiver measurements of phase velocity (2021)
    Oxford University Press
    Details
    Publication Date: 2023-11-14
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2020. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: We compile a data set of Rayleigh-wave phase velocities between pairs of stations, based on teleseismic events located on the same great circle as the two stations. We validate our observations against dispersion estimates based on ambient-noise cross correlations at the same station pairs. Discrepancies between the results of the two methods can in principle be explained by deviations in the wave propagation path between earthquake and receivers, due to lateral heterogeneity in the Earth’s structure, but the latter effect has, so far, not been precisely quantified nor corrected for. We implement an algorithm to measure the arrival angle of earthquake-generated surface waves and correct the dispersion measurements accordingly. Application to a data set from the Central-Western Mediterranean shows that the arrival-angle correction almost entirely accounts for the discrepancy in question, decreasing significantly the velocity bias for a wide range of periods.
    Description: Published
    Description: 1838–1844
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    3-D Q-coda attenuation structure at Mt. Etna (Italy) (2021)
    Oxford University Press
    Details
    Publication Date: 2023-11-16
    Description: This article has been accepted for publication in Geophysical Journal International ©: The Authors 2021. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Uploaded in accordance with the publisher's self-archiving policy.
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2021. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: Three dimensional attenuation images of Mt Etna volcano obtained by the analysis of Q-coda from local volcano-tectonic earthquakes are presented in this work. Seismic sources are confined inside the Etna structure with a maximum focal depth of 35 km below the sea level. The space distribution of the attenuation values was calculated by using 3-D weighting functions derived by the sensitivity kernels of Pacheco & Snieders and approximated by a polynomial interpolation, represented in the maps by using a backprojection method. Data were analyzed in four bands with central frequency placed at 1.5, 3, 6 and 12 Hz, respectively. We observed a frequency dependence of Q-coda with values that range from 55 at 1.5 Hz to 218 at 12 Hz. Q-coda space distribution in the Etna area shows almost uniformity in the average attenuation in the first 35 km below the surface. The images were derived with a resolution of 5 km. We observe as one of our main conclusions that Q-coda attenuation space anomalies are correlated with the areas of highest structural heterogeneities and are distributed along the well-known tectonic structures which characterize the crust in Mt Etna region. Previous and numerous velocity and attenuation images describing the structure of Mt Etna support our main conclusion: high Q-coda volumes almost coincide with the zones marked by high velocity and relative low total attenuation for direct waves.
    Description: Published
    Description: 544–558
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Source modelling and strong ground motion simulations for the 24 January 2020, Mw 6.8 Elazığ earthquake, Turkey (2021)
    Oxford University Press
    Details
    Publication Date: 2023-11-29
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2020. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: On 24 January 2020 an Mw 6.8 earthquake occurred at 20:55 local time (17:55 UTC) in eastern Turkey, close to the town of Sivrice in the Elazığ province, causing widespread considerable seismic damage in buildings. In this study, we analyse the main features of the rupture process and the seismic ground shaking during the Elazığ earthquake. We first use Interferometric Synthetic Aperture Radar (InSAR) interferograms (Sentinel-1 satellites) to constrain the fault geometry and the coseismic slip distribution of the causative fault segment. Then, we utilize this information to analyse the ground motion characteristics of the main shock in terms of peak ground acceleration (PGA), peak ground velocity (PGV) and spectral accelerations. The absence of seismic registrations in near-field for this earthquake imposes major constraints on the computation of seismic ground motion estimations in the study area. To do this, we have used a stochastic finite-fault simulation method to generate high-frequency ground motions synthetics for the Mw 6.8 Elazığ 2020 earthquake. Finally, we evaluate the potential state of stress of the unruptured portions of the causative fault segment as well as of adjacent segments, using the Coulomb stress failure function variations. Modelling of geodetic data shows that the 2020 Elazığ earthquake ruptured two major slip patches (for a total length of about 40 km) located along the Pütürge segment of the well-known left-lateral strike-slip East Anatolian Fault Zone (EAFZ), with up to 2.3 m of slip and an estimated geodetic moment of 1.70 × 1019 Nm (equivalent to a Mw 6.8). The position of the hypocentre supports the evidence of marked WSW rupture directivity during the main shock. In terms of ground motion characteristics, we observe that the high-frequency stochastic ground motion simulations have a good capability to reproduce the source complexity and capture the ground motion attenuation decay as a function of distance, up to the 200 km. We also demonstrate that the design spectra corresponding to 475 yr return period, provided by the new Turkish building code is not exceeded by the simulated seismograms in the epicentral area where there are no strong motion stations and no recordings available. Finally, based on the Coulomb stress distribution computation, we find that the Elazığ main shock increased the stress level of the westernmost part of the Pütürge fault and of the adjacent Palu segment and as a result of an off-fault lobe.
    Description: Published
    Description: 1054–1068
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Ontogeny of osmoregulation of the Asian shore crab Hemigrapsus sanguineus at an invaded site of Europe (2021)
    Oxford University Press
    In:  EPIC3Conservation Physiology, Oxford University Press, 9(1), ISSN: 2051-1434
    Details
    Publication Date: 2024-01-01
    Description: We studied the ontogeny of osmoregulation of the Asian shore crab Hemigrapsus sanguineus at an invaded area in the North Sea. H. sanguineus is native to Japan and China but has successfully invaded the Atlantic coast of North America and Europe. In the invaded areas, H. sanguineus is becoming a keystone species as driver of community structure and the adults compete with the shore crab Carcinus maenas. Strong osmoregulatory abilities may confer the potential to use and invade coastal areas already earlier in the life cycle. We reared larvae and first juveniles at 24°C in seawater from hatching to intermoult of each developmental stage (zoea I-V, megalopa, crab I). We exposed each stage to a range of salinities (0–39 ppt) for 24 h, and then we quantified haemolymph osmolality, using nano-osmometry. In addition, we quantified osmolality in field-collected adults after acclimation to the test salinities for 6 days. Larvae of H. sanguineus were able to hyper-osmoregulate at low salinities (15 and 20 ppt) over the complete larval development, although the capacity was reduced at the zoeal stage V; at higher salinities (25–39 ppt), all larval stages were osmoconformers. The capacity to slightly hypo-regulate at high salinity appeared in the first juvenile. Adults were able to hyper-osmoregulate at low salinities and hypo-regulate at concentrated seawater (39 ppt). H. sanguineus showed a strong capacity to osmoregulate as compared to its native competitor C. maenas, which only hyper-regulates at the first and last larval stages and does not hypo-regulate at the juvenile-adult stages. The capacity of H. sanguineus to osmoregulate over most of the life cycle should underpin the potential to invade empty niches in the coastal zone (characterized by low salinity and high temperatures). Osmoregulation abilities over the whole life cycle also constitute a strong competitive advantage over C. maenas.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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    Full waveform inversion based on the non-parametric estimate of the probability distribution of the residuals (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-27
    Description: Summary In an attempt to overcome the difficulties of the full waveform inversion (FWI), several alternative objective functions have been proposed over the last few years. Many of them are based on the assumption that the residuals (differences between modelled and observed seismic data) follow specific probability distributions when, in fact, the true probability distribution is unknown. This leads FWI to converge to an incorrect probability distribution if the assumed probability distribution is different from the real one and, consequently it may lead the FWI to achieve biased models of the subsurface. In this work, we propose an objective function which does not force the residuals to follow a specific probability distribution. Instead, we propose to use the non-parametric kernel density estimation technique (KDE) (which imposes the least possible assumptions about the residuals) to explore the probability distribution that may be more suitable. As evidenced by the results obtained in a synthetic model and in a typical P-wave velocity model of the Brazilian pre-salt fields, the proposed FWI reveals a greater potential to overcome more adverse situations (such as cycle-skipping) and also a lower sensitivity to noise in the observed data than conventional L2 and L1-norm objective functions and thus making it possible to obtain more accurate models of the subsurface. This greater potential is also illustrated by the smoother and less sinuous shape of the proposed objective function with fewer local minima compared with the conventional objective functions.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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    Phospho-Ku70 induced by DNA damage interacts with RNA Pol II and promotes the formation of phospho-53BP1 foci to ensure optimal cNHEJ (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-30
    Description: Canonical non-homologous end-joining (cNHEJ) is the prominent mammalian DNA double-strand breaks (DSBs) repair pathway operative throughout the cell cycle. Phosphorylation of Ku70 at ser27-ser33 (pKu70) is induced by DNA DSBs and has been shown to regulate cNHEJ activity, but the underlying mechanism remained unknown. Here, we established that following DNA damage induction, Ku70 moves from nucleoli to the sites of damage, and once linked to DNA, it is phosphorylated. Notably, the novel emanating functions of pKu70 are evidenced through the recruitment of RNA Pol II and concomitant formation of phospho-53BP1 foci. Phosphorylation is also a prerequisite for the dynamic release of Ku70 from the repair complex through neddylation-dependent ubiquitylation. Although the non-phosphorylable ala-Ku70 form does not compromise the formation of the NHEJ core complex per se, cells expressing this form displayed constitutive and stress-inducible chromosomal instability. Consistently, upon targeted induction of DSBs by the I-SceI meganuclease into an intrachromosomal reporter substrate, cells expressing pKu70, rather than ala-Ku70, are protected against the joining of distal DNA ends. Collectively, our results underpin the essential role of pKu70 in the orchestration of DNA repair execution in living cells and substantiated the way it paves the maintenance of genome stability.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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    Differential rotation in a 3D simulation of oxygen shell burning (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-27
    Description: We study differential rotation in late-stage shell convection in a 3D hydrodynamic simulation of a rapidly rotating 16 M⊙ helium star with a particular focus on the convective oxygen shell. We find that the oxygen shell develops a quasi-stationary pattern of differential rotation that is neither described by uniform angular velocity as assumed in current stellar evolution models of supernova progenitors, nor by uniform specific angular momentum. Instead, the oxygen shell develops a positive angular velocity gradient with faster rotation at the equator than at the pole by tens of percent. We show that the angular momentum transport inside the convection zone is not adequately captured by a diffusive mixing-length flux proportional to the angular velocity or angular momentum gradient. Zonal flow averages reveal stable large-scale meridional flow and an entropy deficit near the equator that mirrors the patterns in the angular velocity. The structure of the flow is reminiscent of simulations of stellar surface convection zones and the differential rotation of the Sun, suggesting that similar effects are involved; future simulations will need to address in more detail how the interplay of buoyancy, inertial forces, and turbulent stresses shapes differential rotation during late-stage convection in massive stars. If convective regions develop positive angular velocity gradients, angular momentum could be shuffled out of the core region more efficiently, potentially making the formation of millisecond magnetars more difficult. Our findings have implications for neutron star birth spin periods and supernova explosion scenarios that involve rapid core rotation.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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    Characterising the distinct crustal protoliths of Roberts Victor Type I and II eclogites (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-27
    Description: The origin of the eclogites that reside in cratonic mantle roots has long been debated. In the classic Roberts Victor kimberlite locality in South Africa, the strongly contrasting textural and geochemical features of two types of eclogites have led to different genetic models. We studied a new suite of 63 eclogite xenoliths from the former Roberts Victor Mine. In addition to major- and trace-element compositions for all new samples, we determined 18O/16O for garnet from 34 eclogites. Based on geochemical and textural characteristics we identify a large suite of Type I eclogites (n = 53) consistent with previous interpretations that these rocks originate from metamorphosed basaltic-picritic lavas or gabbroic cumulates from oceanic crust, crystallised from melts of depleted MORB mantle. We identify a smaller set of Type II eclogites (n = 10) based on geochemical and textural similarity to eclogites in published literature. We infer their range to very low δ18O values combined with their varied, often very low Zr/Hf ratios and LREE-depleted nature to indicate a protolith origin via low-pressure clinopyroxene-bearing oceanic cumulates formed from melts that were more depleted in incompatible elements than N-MORB. These compositions are indicative of derivation from a residual mantle source that experienced preferential extraction of incompatible elements and fractionation of Zr-Hf during previous melting.
    Print ISSN: 0022-3530
    Electronic ISSN: 1460-2415
    Topics: Geosciences
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    Evidence for an expanding corona based on spectral-timing modelling of multiple black hole X-ray binaries (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-27
    Description: Galactic black hole X-ray binaries (BHXBs) provide excellent laboratories to study accretion, as their relatively quick evolution allows us to monitor large changes in the in-flowing and/or out-flowing material over human timescales. However, the details of how the inflow-outflow coupling evolves during a BHXB outburst remain an area of active debate. In this work we attempt to probe the physical changes underlying the system evolution, by performing a systematic analysis of the multi-wavelength data of three BHXB sources: XTE J1752-223, MAXI J1659-152, and XTE J1650-500, during hard and hard-intermediate states. Using the power spectral hue which characterises the X-ray variability properties, we identify several clusters of BHXB epochs and perform the joint multi-wavelength spectral modelling to test their commonality with a physical jet model. Under the assumption that the corona is related to the base of the jet, we find that the power spectral hue traces the variation of the coronal radius (from ∼10Rg − ∼ 40Rg) in multiple BHXBs at hard and hard-intermediate states, and that the data are consistent with moderately truncated accretion discs (
    Print ISSN: 0035-8711
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    The Power of Word-Frequency Based Alignment-Free Functions: a Comprehensive Large-Scale Experimental Analysis (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-30
    Description: Motivation Alignment-free (AF) distance/similarity functions are a key tool for sequence analysis. Experimental studies on real datasets abound and, to some extent, there are also studies regarding their control of false positive rate (Type I error). However, assessment of their power, i.e., their ability to identify true similarity, has been limited to some members of the D2 family. The corresponding experimental studies have concentrated on short sequences, a scenario no longer adequate for current applications, where sequence lengths may vary considerably. Such a State of the Art is methodologically problematic, since information regarding a key feature such as power is either missing or limited. Results By concentrating on a representative set of word-frequency based AF functions, we perform the first coherent and uniform evaluation of the power, involving also Type I error for completeness. Two Alternative models of important genomic features (CIS Regulatory Modules and Horizontal Gene Transfer), a wide range of sequence lengths from a few thousand to millions, and different values of k have been used. As a result, we provide a characterization of those AF functions that is novel and informative. Indeed, we identify weak and strong points of each function considered, which may be used as a guide to choose one for analysis tasks. Remarkably, of the fifteen functions that we have considered, only four stand out, with small differences between small and short sequence length scenarios. Finally, in order to encourage the use of our methodology for validation of future AF functions, the Big Data platform supporting it is public. Availability The software is available at: https://github.com/pipp8/power_statistics Supplementary information Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
    Published by Oxford University Press
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    Dark energy survey year 3 results: Galaxy sample for BAO measurement (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-27
    Description: In this paper we present and validate the galaxy sample used for the analysis of the Baryon Acoustic Oscillation signal (BAO) in the Dark Energy Survey (DES) Y3 data. The definition is based on a colour and redshift-dependent magnitude cut optimized to select galaxies at redshifts higher than 0.5, while ensuring a high quality determination. The sample covers ∼ 4100 square degrees to a depth of i = 22.3 (AB) at 10σ. It contains 7,031,993 galaxies in the redshift range from z= 0.6 to 1.1, with a mean effective redshift of 0.835. Redshifts are estimated with the machine learning algorithm DNF, and are validated using the VIPERS PDR2 sample. We find a mean redshift bias of zbias ∼  0.01 and a mean uncertainty, in units of 1 + z, of σ68 ∼  0.03. We evaluate the galaxy population of the sample, showing it is mostly built upon Elliptical to Sbc types. Furthermore, we find a low level of stellar contamination of $lesssim 4{{ m per cent}}$. We present the method used to mitigate the effect of spurious clustering coming from observing conditions and other large-scale systematics. We apply it to the BAO sampleand calculate weights that are used to get a robust estimate of the galaxy clustering signal. This paper is one of a series dedicated to the analysis of the BAO signal in DES Y3. In the companion papers we present the galaxy mock catalogues used to calibrate the analysis and the angular diameter distance constraints obtained through the fitting to the BAO scale.
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    Topics: Physics
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    Finite-difference modeling of 2-D wave propagation in the vicinity of dipping interfaces: a comparison of anti-aliasing and equivalent medium approaches (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-28
    Description: Summary Finite-difference (FD) modeling of seismic waves in the vicinity of dipping interfaces gives rise to artifacts. Examples are phase and amplitude errors, as well as staircase diffractions. Such errors can be reduced in two general ways. In the first approach, the interface can be anti-aliased (i.e., with an anti-aliased step-function, or a lowpass filter). Alternatively, the interface may be replaced with an equivalent medium (i.e., using Schoenberg & Muir (SM) calculus or orthorhombic averaging). We test these strategies in acoustic, elastic isotropic, and elastic anisotropic settings. Computed FD solutions are compared to analytical solutions. We find that in acoustic media, anti-aliasing methods lead to the smallest errors. Conversely, in elastic media, the SM calculus provides the best accuracy. The downside of the SM calculus is that it requires an anisotropic FD solver even to model an interface between two isotropic materials. As a result, the computational cost increases compared to when using isotropic FD solvers. However, since coarser grid spacings can be used to represent the dipping interfaces, the two effects (an expensive FD solver on a coarser FD grid) equal out. Hence, the SM calculus can provide an efficient means to reduce errors, also in elastic isotropic media.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
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    Relativistic effects on triple black holes: Burrau’s problem revisited (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-28
    Description: We explore, using numerical simulations, the influence of mass and distance on the evolution of triple black hole systems. Following in the direction of Burrau’s famous 3,4,5 problem, black holes are initially placed at the vertices of Pythagorean triangles. Numerical integration of orbits was conducted using relativistic corrections (post-Newtonian) up to the 2.5th order with ARCcode. As a descriptor of the evolution of the systems, the lifetimes, the number of two-body encounters and the number of mergers were all analysed. We found that as the mass unit of the black holes increased there was strong positive correlation with the fraction of mergers (0.9868), strong negative correlation with the average number of two-body encounters (-0.9016) and the average lifetimes of the triple systems decayed exponentially (determination coefficient of 0.9986). Around the mass unit range of 105.5M⊙-105.6M⊙, there was a transition from escape dominated dynamics to merger dominated dynamics. However, in the mass unit range of 106 M⊙ − 109M⊙ with 1 pc distance unit, we find that 25 per cent of cases resulted in the escape of a supermassive black hole (SMBH) which may be a cause for wandering SMBH’s found in some galaxies/galactic merger remnants.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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    Deep searches for X-ray pulsations from Scorpius X-1 and Cygnus X-2 in support of continuous gravitational wave searches (2021)
    Oxford University Press
    Details
    Publication Date: 2021-10-27
    Description: Neutron stars in low mass X-ray binaries are hypothesised to emit continuous gravitational waves that may be detectable by ground-based observatories. The torque balance model predicts that a higher accretion rate produces larger-amplitude gravitational waves, hence low mass X-ray binaries with high X-ray flux are promising targets for gravitational wave searches. The detection of X-ray pulsations would identify the spin frequency of these neutron stars, and thereby improve the sensitivity of continuous gravitational-wave searches by reducing the volume of the search parameter space. We perform a semi-coherent search for pulsations in the two low mass X-ray binaries Scorpius X-1 and Cygnus X-2 using X-ray data from the Rossi X-ray Timing Explorer Proportional Counter Array. We find no clear evidence for pulsations, and obtain upper limits (at 90 per cent confidence) on the fractional pulse amplitude, with the most stringent being 0.034 per cent for Scorpius X-1 and 0.23 per cent for Cygnus X-2. These upper limits improve upon those in previous work by factors of ∼8.2 and ∼1.6 respectively.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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    On the detection of multiple shock fronts in A1914 using deep Chandra X-ray observations (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: Here, we report the new detection of three shock fronts using archival Chandra X-ray observations in Abell 1914, which also hosts a radio halo, a radio phoenix, and a head-tail galaxy. In this study, we report the X-ray shock front at the position of the radio phoenix, which further strengthens the scenario that radio phoenix traces old plasma that gets lit up when compressed by shock passage. We further analyse the thermodynamic structure of the cluster in detail. We create temperature maps of A1914 using three different techniques, Adaptive Circular Binning (ACB), Weighted Voronoi Tessellations (WVT), and Contour binning (Contbin) method. These thermodynamic maps, along with the pseudo pressure and the pseudo entropy maps for the cluster, are evidence of disturbed morphology produced by multiple merger events. These merger events create cluster-wide turbulence, which may re-accelerate the relativistic particles and result in a radio halo within the cluster. Further, comparing X-ray and radio images reveals that the radio halo is contained within two X-ray shock fronts. Our analysis suggests that A1914 has both equatorial shock and axial shock within the cluster’s ICM. We proposed a dual merging scenario based on the shock position and analysis of the thermodynamic maps obtained from the deeper Chandra X-ray observations.
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    Topics: Physics
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    The impact of metallicity on nova populations (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: The metallicity of a star affects its evolution in a variety of ways, changing stellar radii, luminosities, lifetimes, and remnant properties. In this work, we use the population synthesis code binary_c to study how metallicity affects novae in the context of binary stellar evolution. We compute a 16-point grid of metallicities ranging from Z = 10−4 to 0.03, presenting distributions of nova white dwarf masses, accretion rates, delay-times, and initial system properties at the two extremes of our 16-point metallicity grid. We find a clear anti-correlation between metallicity and the number of novae produced, with the number of novae at Z = 0.03 roughly half that at Z = 10−4. The white dwarf mass distribution has a strong systematic variation with metallicity, while the shape of the accretion rate distribution is relatively insensitive. We compute a current nova rate of approximately 33 novae per year for the Milky Way, a result consistent with observational estimates relying on extra-Galactic novae but an under-prediction relative to observational estimates relying on Galactic novae. However, the shape of our predicted Galactic white dwarf mass distribution differs significantly to existing observationally derived distributions, likely due to our underlying physical assumptions. In M31, we compute a current nova rate of approximately 36 novae per year, under-predicting the most recent observational estimate of $65^{+15}_{-16}$. Finally, we conclude that when making predictions about currently observable nova rates in spiral galaxies, or stellar environments where star formation has ceased in the distant past, metallicity can likely be considered of secondary importance compared to uncertainties in binary stellar evolution.
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    Tracing the evolution of human gene regulation and its association with shifts in environment (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: As humans populated the world, they adapted to many varying environmental factors, including climate, diet, and pathogens. Because many of these adaptations were mediated by multiple non-coding variants with small effects on gene regulation, it has been difficult to link genomic signals of selection to specific genes, and to describe the regulatory response to selection. To overcome this challenge, we adapted PrediXcan, a machine learning method for imputing gene regulation from genotype data, to analyze low-coverage ancient human DNA (aDNA). First, we used simulated genomes to benchmark strategies for adapting PrediXcan to increase robustness to incomplete data. Applying the resulting models to 490 ancient Eurasians, we found that genes with the strongest divergent regulation among ancient populations with hunter-gatherer, pastoralist, and agricultural lifestyles are enriched for metabolic and immune functions. Next, we explored the contribution of divergent gene regulation to two traits with strong evidence of recent adaptation: dietary metabolism and skin pigmentation. We found enrichment for divergent regulation among genes proposed to be involved in diet-related local adaptation, and the predicted effects on regulation often suggest explanations for known signals of selection, e.g. at FADS1, GPX1, and LEPR. In contrast, skin pigmentation genes show little regulatory change over a 38,000-year time series of 2999 ancient Europeans, suggesting that adaptation mainly involved large-effect coding variants. This work demonstrates that combining aDNA with present-day genomes is informative about the biological differences among ancient populations, the role of gene regulation in adaptation, and the relationship between genetic diversity and complex traits.
    Electronic ISSN: 1759-6653
    Topics: Biology
    Published by Oxford University Press
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    Analysis of sex chromosome evolution in the clade Palaeognathae from phased genome assembly (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: Birds in the clade Palaeognathae, excluding Tinamiformes, have morphologically conserved karyotypes and less differentiated ZW sex chromosomes compared with those of other birds. In particular, the sex chromosomes of the ostrich and emu have exceptionally large recombining pseudoautosomal regions (PARs), while non-PARs are classified into two strata according to the date of their origins: stratum 0 (S0) and stratum 1 (S1). However, the construction and analysis of the genome sequences in these regions in the clade Palaeognathae can be challenging because assembling the S1 region is difficult owing to low sequence diversity between gametologs (Z-linked and W-linked sequences). We addressed this issue by applying the Platanus-allee assembler and successfully constructed the haplotype-resolved (phased) assembly for female emu, cassowary, and ostrich using only sequence read data derived from the Illumina platform. Comparative genomic and phylogenetic analyses based on assembled Z-linked and W-linked sequences confirmed that the S1 region of emu and cassowary formed in their common ancestor. Moreover, the interspersed repetitive sequence landscapes in the S1 regions of female emu showed an expansion of younger repetitive elements in the W-linked S1 region, suggesting an interruption in homologous recombination in the S1 region. These results provide novel insights into the trajectory of sex chromosome evolution in the clade Palaeognathae and suggest that the Illumina-based phased assembly method is an effective approach for elucidating the evolutionary process underlying the transition from homomorphic to differentiated sex chromosomes.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 89
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    Multi-Fidelity Emulation for the Matter Power Spectrum using Gaussian Processes (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: We present methods for emulating the matter power spectrum by combining information from cosmological N-body simulations at different resolutions. An emulator allows estimation of simulation output by interpolating across the parameter space of a limited number of simulations. We present the first implementation in cosmology of multi-fidelity emulation, where many low-resolution simulations are combined with a few high-resolution simulations to achieve an increased emulation accuracy. The power spectrum’s dependence on cosmology is learned from the low-resolution simulations, which are in turn calibrated using high-resolution simulations. We show that our multi-fidelity emulator predicts high-fidelity counterparts to percent-level relative accuracy when using only 3 high-fidelity simulations and outperforms a single-fidelity emulator that uses 11 simulations, although we do not attempt to produce a converged emulator with high absolute accuracy. With a fixed number of high-fidelity training simulations, we show that our multi-fidelity emulator is ≃ 100 times better than a single-fidelity emulator at k ≤ 2 hMpc−1, and ≃ 20 times better at 3 ≤ k 〈 6.4 hMpc−1. Multi-fidelity emulation is fast to train, using only a simple modification to standard Gaussian processes. Our proposed emulator shows a new way to predict non-linear scales by fusing simulations from different fidelities.
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    Population genomics of wall lizards reflects the dynamic history of the Mediterranean Basin (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: The Mediterranean Basin has experienced extensive change in geology and climate over the past six million years. Yet, the relative importance of key geological events for the distribution and genetic structure of the Mediterranean fauna remains poorly understood. Here, we use population genomic and phylogenomic analyses to establish the evolutionary history and genetic structure of common wall lizards (Podarcis muralis). This species is particularly informative because, in contrast to other Mediterranean lizards, it is widespread across the Iberian, Italian, and Balkan peninsulas, and in extra-Mediterranean regions. We found strong support for six major lineages within P. muralis, which were largely discordant with the phylogenetic relationship of mitochondrial DNA. The most recent common ancestor of extant P. muralis was likely distributed in the Italian Peninsula, and experienced an “Out-of-Italy” expansion following the Messinian salinity crisis (∼5 Mya), resulting in the differentiation into the extant lineages on the Iberian, Italian and Balkan peninsulas. Introgression analysis revealed that both inter- and intraspecific gene flows have been pervasive throughout the evolutionary history of P. muralis. For example, the Southern Italy lineage has a hybrid origin, formed through admixture between the Central Italy lineage and an ancient lineage that was the sister to all other P. muralis. More recent genetic differentiation is associated with the onset of the Quaternary glaciations, which influenced population dynamics and genetic diversity of contemporary lineages. These results demonstrate the pervasive role of Mediterranean geology and climate for the evolutionary history and population genetic structure of extant species.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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    Five-percent measurements of the growth rate from simulation-based modelling of redshift-space clustering in BOSS LOWZ (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: We use a simulation-based modelling approach to analyse the anisotropic clustering of the BOSS LOWZ sample over the radial range 0.4 h−1 Mpc to 63 h−1 Mpc, significantly extending what is possible with a purely analytic modelling framework. Our full-scale analysis yields constraints on the growth of structure that are a factor of two more stringent than any other study on large scales at similar redshifts. We infer fσ8 = 0.471 ± 0.024 at z ≈ 0.25, and fσ8 = 0.430 ± 0.025 at z ≈ 0.40; the corresponding ΛCDM predictions of the Planck CMB analysis are 0.470 ± 0.006 and 0.476 ± 0.005, respectively. Our results are thus consistent with Planck, but also follow the trend seen in previous low-redshift measurements of fσ8 falling slightly below the ΛCDM+CMB prediction. We find that small and large radial scales yield mutually consistent values of fσ8, but there are 1 − 2.5σ hints of small scales (
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    Genome-wide reconstruction of rediploidization following autopolyploidization across one hundred million years of salmonid evolution (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: The long-term evolutionary impacts of whole genome duplication (WGD) are strongly influenced by the ensuing rediploidization process. Following autopolyploidization, rediploidization involves a transition from tetraploid to diploid meiotic pairing, allowing duplicated genes (ohnologues) to diverge genetically and functionally. Our understanding of autopolyploid rediploidization has been informed by a WGD event ancestral to salmonid fishes, where large genomic regions are characterized by temporally delayed rediploidization, allowing lineage-specific ohnologue sequence divergence in the major salmonid clades. Here, we investigate the long-term outcomes of autopolyploid rediploidization at genome-wide resolution, exploiting a recent ‘explosion’ of salmonid genome assemblies, including a new genome sequence for the huchen (Hucho hucho). We developed a genome alignment approach to capture duplicated regions across multiple species, allowing us to create 121,864 phylogenetic trees describing genome-wide ohnologue divergence across salmonid evolution. Using molecular clock analysis, we show that 61% of the ancestral salmonid genome experienced an initial ‘wave’ of rediploidization in the late Cretaceous (85-106 Mya). This was followed by a period of relative genomic stasis lasting 17-39 My, where much of the genome remained tetraploid. A second rediploidization wave began in the early Eocene and proceeded alongside species diversification, generating predictable patterns of lineage-specific ohnologue divergence, scaling in complexity with the number of speciation events. Using gene set enrichment, gene expression, and codon-based selection analyses, we provide insights into potential functional outcomes of delayed rediploidization. This study enhances our understanding of delayed autopolyploid rediploidization and has broad implications for future studies of WGD events.
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    Ubiquitin-dependent rapid degradation conceals a cell-protective function of cytoplasmic SIRT3 against oxidative stress (2021)
    Oxford University Press
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    Publication Date: 2021-10-29
    Description: SIRT3 is an NAD+-dependent protein deacetylase localized in mitochondria. Several studies reported localization of SIRT3 in the cytoplasm or nucleus, but data of these studies were not consistent. We detected expression of mitochondrial (SIRT3mt) and cytoplasmic (SIRT3ct) Sirt3 mRNAs in the mouse brain, and we also found SIRT3 immunostaining of mitochondria and cytoplasm in the brain and cultured neural cells. However, expression levels of SIRT3ct in COS cells transfected with SIRT3ct cDNA were much lower than those of SIRT3mt. We found that SIRT3ct but not SIRT3mt was promptly degraded by ubiquitin-dependent degradation, in which SIRT3ct degradation was mediated mainly by ubiquitination of NH2-terminal methionine and partly by that of lysine residues of SIRT3ct. SIRT3ct expression level was significantly enhanced by treatment of cells with staurosporine or H2O2. H2O2 treatment promoted nuclear translocation of SIRT3ct and induced histone H3 deacetylation and superoxide dismutase 2 expression. Overexpression of SIRT3ct decreased cell death caused by H2O2 at levels similar to those achieved by overexpression of SIRT3mt. Knockdown of Sirt3 mRNA increased cell death caused by amyloid-β (Aβ), and overexpression of SIRT3ct suppressed the toxic function of Aβ in PC12 cells. These results indicate that SIRT3ct promotes cell survival under physiological and pathological conditions.
    Print ISSN: 0021-924X
    Electronic ISSN: 1756-2651
    Topics: Biology , Chemistry and Pharmacology
    Published by Oxford University Press on behalf of Japanese Biochemical Society.
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    The Jun-dependent axon regeneration gene program: Jun promotes regeneration over plasticity (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: The regeneration-associated gene (RAG) expression program is activated in injured peripheral neurons after axotomy and enables long-distance axon re-growth. Over 1000 genes are regulated, and many transcription factors are upregulated or activated as part of this response. However, a detailed picture of how RAG expression is regulated is lacking. In particular the transcriptional targets and specific functions of the various transcription factors are unclear. Jun was the first regeneration-associated transcription factor identified and the first shown to be functionally important. Here we fully define the role of Jun in the RAG expression program in regenerating facial motor neurons. At 1, 4, and 14 days after axotomy, Jun upregulates 11%, 23% and 44% of the RAG program, respectively. Jun functions relevant to regeneration include cytoskeleton production, metabolic functions and cell activation, and the down-regulation of neurotransmission machinery. In silico analysis of promoter regions of Jun targets identifies stronger over-representation of AP1-like sites than CRE-like sites, although CRE sites were also over-represented in regions flanking AP1 sites. Strikingly, in motor neurons lacking Jun, an alternative SRF-dependent gene expression program is initiated after axotomy. The promoters of these newly expressed genes exhibit over-representation of CRE sites in regions near to SRF target sites. This alternative gene expression program includes plasticity-associated transcription factors, and leads to an aberrant early increase in synapse density on motor neurons. Jun thus has the important function in the early phase after axotomy of pushing the injured neuron away from a plasticity response and towards a regenerative phenotype.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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    Spatiotemporal evolution of the global species diversity of Rhododendron (2021)
    Oxford University Press
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    Publication Date: 2021-10-28
    Description: Evolutionary radiation is a widely recognized mode of species diversification, but its underlying mechanisms have not been unambiguously resolved for species-rich cosmopolitan plant genera. In particular, it remains largely unknown how biological and environmental factors have jointly driven its occurrence in specific regions. Here we use Rhododendron, the largest genus of woody plants in the Northern Hemisphere, to investigate how geographic and climatic factors, as well as functional traits, worked together to trigger plant evolutionary radiations and shape the global patterns of species richness based on a solid species phylogeny. Using 3437 orthologous nuclear genes, we reconstructed the first highly supported and dated backbone phylogeny of Rhododendron comprising 200 species that represent all subgenera, sections, and nearly all multi-species subsections, and found that most extant species originated by evolutionary radiations when the genus migrated southwards from circumboreal areas to tropical/subtropical mountains, showing rapid increases of both net diversification rate and evolutionary rate of environmental factors in the Miocene. We also found that the geographically uneven diversification of Rhododendron led to a much higher diversity in Asia than in other continents, which was mainly driven by two environmental variables, i.e., elevation range and annual precipitation, and were further strengthened by the adaptation of leaf functional traits. Our study provides a good example of integrating phylogenomic and ecological analyses in deciphering the mechanisms of plant evolutionary radiations, and sheds new light on how the intensification of the Asian monsoon has driven evolutionary radiations in large plant genera of the Himalaya-Hengduan Mountains.
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    Topics: Biology
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    Interpreting Internal Consistency of DES Measurements (2021)
    Oxford University Press
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    Publication Date: 2021-10-29
    Description: Bayesian evidence ratios are widely used to quantify the statistical consistency between different experiments. However, since the evidence ratio is prior dependent, the precise translation between its value and the degree of concordance/discordance requires additional information. The most commonly adopted metric, the Jeffreys scale, can falsely suggest agreement between datasets when priors are chosen to be sufficiently wide. This work examines evidence ratios in a DES-Y1 simulated analysis, focusing on the internal consistency between weak lensing and galaxy clustering. We study two scenarios using simulated data in controlled experiments. First, we calibrate the expected evidence ratio distribution given noise realizations around the best fit DES-Y1 ΛCDM cosmology. Second, we show the behavior of evidence ratios for noiseless fiducial data vectors simulated using a modified gravity model, which generates internal tension in the LCDM analysis. We find that the evidence ratio of noise realizations generated at all confidence levels was biased towards agreement and show, with a modified gravity model, that the choice of prior could conceal the discrepancies between weak lensing and galaxy clustering induced by prior effects in unlike cosmological models, concluding that the evidence ratio in a DES-Y1 study is, indeed, biased towards agreement. Boundary effects can also influence conclusions about the inconsistency induced by modified gravity, even in a noiseless data vector simulation.
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    The extreme properties of the nearby hyper-Eddington accreting Active Galactic Nucleus in IRAS 04416+1215 (2021)
    Oxford University Press
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    Publication Date: 2021-10-30
    Description: The physical properties of the accretion flow and of the X-ray emitting plasma, in supermassive black holes accreting at extreme Eddington rates, are still very unclear. Here we present the analysis of simultaneous XMM-Newton and NuSTAR observations of the hyper-Eddington Seyfert 1 galaxy IRAS 04416+1215, carried out in 2020. The main goal of these observations is to investigate the properties of the X-ray corona, as well as the structure of the accretion flow and of the circumnuclear environment, in this regime of extreme accretion. IRAS 04416+1215 has one of the highest Eddington ratio (λEdd ≃ 472) in the local Universe. It shows an interesting spectral shape, very similar to the standard Narrow Line Seyfert 1 galaxy’s spectra, with the presence of multi-phase absorption structure composed of three phases, whose estimate of the minimum and maximum distances suggests two different interpretations, one consistent with the three X-ray winds being co-spatial, and possibly driven by magnetohydrodynamical processes, the other consistent with the multi-phase winds being also multi-scale. The X-ray spectrum of IRAS 04416+1215 also has a prominent soft excess component and a hard X-ray emission dominated by a reflection component. Moreover, our detailed spectral analysis shows that IRAS 04416+1215 has the lowest coronal temperature measured so far by NuSTAR (kTe = 3 − 22 keV, depending on the model). This is consistent with a hybrid coronal plasma, in which the primary continuum emission is driven by pair production due to high-energy tail of the energy distribution of non-thermal electrons.
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    Kinematics and structure of Ionized gas in the UCHII regions of W33 main (2021)
    Oxford University Press
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    Publication Date: 2021-10-29
    Description: High mass proto-stars create Ultra-Compact H ii regions (UCHII) at the stage of evolution when most of the accretion is finished but the star is still heavily embedded in molecular material. The morphologies of UCHII regions reflect the interactions of stellar winds, stellar motions, and density structure in the molecular cloud; they are complex and it has been very difficult to interpret them. We here present data obtained with TEXES on the NASA IRTF of the [Nei,ii] emission line in the proto-cluster of young OB stars in W33 Main. The data cube has a spatial resolution of ∼1.4 arcsec and true velocity resolution ∼5 km s-1; with Aλ ∼ 0.02AV it is relatively unaffected by extinction. We have run 3D hydrodynamic and line profile simulations, using PLUTO and RADMC-3D, of the gas structures created by multiple windy stars moving relative to each other through the ambient cloud. By iterative comparison of the data cube and the simulations, we arrive at models that reproduce the different morphology and kinematic structure of each UCHII region in W33 Main. The results indicate that each sub-source probably holds multiple exciting stars, permitting an improved view of the stellar population, and finds the stellar trajectories, which may determine the dynamical development of the proto-cluster.
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    Data-Efficient Classification of Radio Galaxies (2021)
    Oxford University Press
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    Publication Date: 2021-10-30
    Description: The continuum emission from radio galaxies can be generally classified into different morphological classes such as FRI, FRII, Bent, or Compact. In this paper, we explore the task of radio galaxy classification based on morphology using deep learning methods with a focus on using a small scale dataset (∼2000 samples). We apply few-shot learning techniques based on Twin Networks and transfer learning techniques using a pre-trained DenseNet model with advanced techniques like cyclical learning rate and discriminative learning to train the model rapidly. We achieve a classification accuracy of over 92% using our best performing model with the biggest source of confusion being between Bent and FRII type galaxies. Our results show that focusing on a small but curated dataset along with the use of best practices to train the neural network can lead to good results. Automated classification techniques will be crucial for upcoming surveys with next generation radio telescopes which are expected to detect hundreds of thousands of new radio galaxies in the near future.
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    Lensing of gravitational waves as a probe of compact dark matter (2021)
    Oxford University Press
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    Publication Date: 2021-10-29
    Description: We study gravitational lensing of gravitational waves from compact object binaries as a probe of compact dark matter (DM) objects such as primordial black holes. Assuming a point mass lens, we perform parameter estimation of lensed gravitational wave signals from compact object binaries to determine the detectability of the lens with ground based laser interferometers. Then, considering binary populations that LIGO-Virgo has been probing, we derive a constraint on the abundance of compact DM from non-observation of lensed events. We find that the LIGO-Virgo observations imply that compact objects heavier than Ml = 200 M⊙ can not constitute all DM and less than $40{{ m per cent}}$ of DM can be in compact objects heavier than Ml = 400 M⊙. We also show that the DM fraction in compact objects can be probed by LIGO in its final sensitivity for Ml 〉 40 M⊙ reaching $2{{ m per cent}}$ of the DM abundance at Ml 〉 200 M⊙, and by ET for Ml 〉 1 M⊙ reaching DM fraction as low as 7 × 10−5 at Ml 〉 40 M⊙.
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