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  • Canadian Science Publishing
  • Springer Science + Business Media
  • Wiley-Blackwell
  • 2015-2019  (2,895)
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  • 1
    Publication Date: 2021-06-16
    Description: In this study, Mg/Ca, Sr/Ca and Ba/Ca ratios in a Lateglacial to Holocene stalagmite (CC26) from Corchia Cave (central Italy) are compared with stable isotope data to define palaeohydrological changes. For most of the record, the trace element ratios show small absolute variability but similar patterns, which are also consistent with stable isotope variations. Higher trace element-to-calcium values are interpreted as responses to decreasing moisture, inducing changes in the residence time of percolation, producing prior calcite precipitation and/or variations in the hydrological routing. Statistically meaningful levels of covariability were determined using anomalies of Mg/Ca, d18O and d13C. Combining these three time series into a single ‘palaeomoisture-trend’ parameter, we highlight several events of reduced moisture (ca. 8.9–8.4, 6.2, 4.2, 3.1 and 2.0 ka), a humid period between ca. 7.9 and 8.3 ka and other shorter-term wet events at ca. 5.8, 5.3 and 3.7 ka. Most of these events can be correlated with climate changes inferred from other regional studies. For both extremities of the record (i.e. before ca. 12.4 ka and after ca. 0.5 ka) Mg/Ca and Sr/Ca are anti-correlated and show the greatest amplitude of values, a likely explanation for which involves aragonite and/or gypsum precipitation (the latter derived from pyrite oxidation) above the CC26 drip point.
    Description: Published
    Description: 381–392
    Description: 4A. Clima e Oceani
    Description: JCR Journal
    Description: restricted
    Keywords: central Italy; Corchia Cave; Holocene; speleothems; trace elements ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-06-14
    Description: This study is focused on the (micro)biogeochemical features of two close geothermal sites (FAV1 and FAV2), both selected at the main exhalative area of Pantelleria Island, Italy. A previous biogeochemical survey revealed high CH4 consumption and the presence of a diverse community of methanotrophs at FAV2 site, whereas the close site FAV1 was apparently devoid of methanotrophs and recorded no CH4 consumption. Next-Generation Sequencing (NGS) techniques were applied to describe the bacterial and archaeal communities which have been linked to the physicochemical conditions and the geothermal sources of energy available at the two sites. Both sites are dominated by Bacteria and host a negligible component of ammonia-oxidizing Archaea (phylum Thaumarchaeota). The FAV2 bacterial community is characterized by an extraordinary diversity of methanotrophs, with 40% of the sequences assigned to Methylocaldum, Methylobacter (Gammaproteobacteria) and Bejerickia (Alphaproteobacteria); conversely, a community of thermo-acidophilic chemolithotrophs (Acidithiobacillus, Nitrosococcus) or putative chemolithotrophs (Ktedonobacter) dominates the FAV1 community, in the absence of methanotrophs. Since physical andchemical factors of FAV1, such as temperature and pH, cannot be considered limiting for methanotrophy, it is hypothesized that the main limiting factor for methanotrophs could be high NH4+ concentration. At the same time, abundant availability of NH4+ and other high energy electron donors and acceptors determined by the hydrothermal flux in this site create more energetically favourable conditions for chemolithotrophs that outcompete methanotrophs in non-nitrogen-limited soils.
    Description: Published
    Description: 150–162
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: geothermal soils ; geomicrobiology ; chemolithotrophs ; methanotrophs ; Pantelleria ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2021-03-18
    Description: This article presents an integrated approach for the probabilistic systemic risk analysis of a road network considering spatial seismic hazard with correlation of ground motion intensities, vulnerability of the network components, and the effect of interactions within the network, as well as, between roadway components and built environment to the network functionality. The system performance is evaluated at the system level through a global connectivity performance indicator, which depends on both physical damages to its components and induced functionality losses due to interactions with other systems. An object-oriented modeling paradigm is used, where the complex problem of several interacting systems is decomposed in a number of interacting objects, accounting for intra- and interdependencies between and within systems. Each system is specified with its components, solving algorithms, performance indicators and interactions with other systems. The proposed approach is implemented for the analysis of the road network in the city of Thessaloniki (Greece) to demonstrate its applicability. In particular, the risk for the road network in the area is calculated, specifically focusing on the short-term impact of seismic events (just after the earthquake). The potential of road blockages due to collapses of adjacent buildings and overpass bridges is analyzed, trying to individuate possible criticalities related to specific components/subsystems. The application can be extended based on the proposed approach, to account for other interactions such as failure of pipelines beneath the road segments, collapse of adjacent electric poles, or malfunction of lighting and signaling systems due to damage in the electric power network.
    Description: Published
    Description: 524–540
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Systemic vulnerability ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2020-12-14
    Description: The knowledge of the local soil structure is important for the assessment of seismic hazards. A widespread, but time-consuming technique to retrieve the parameters of the local underground is the drilling of boreholes. Another way to obtain the shear wave velocity profile at a given location is the inversion of surface wave dispersion curves. To ensure a good resolution for both superficial and deeper layers, the used dispersion curves need to cover a wide frequency range. This wide frequency range can be obtained using several arrays of seismic sensors or a single array comprising a large number of sensors. Consequently, these measurements are time-consuming. A simpler alternative is provided by the use of the ellipticity of Rayleigh waves. The frequency dependence of the ellipticity is tightly linked to the shear wave velocity profile. Furthermore, it can be measured using a single seismic sensor. As soil structures obtained by scaling of a given model exhibit the same ellipticity curve, any inversion of the ellipticity curve alone will be ambiguous. Therefore, additional measurements which fix the absolute value of the shear wave velocity profile at some points have to be included in the inversion process. Small-scale spatial autocorrelation measurements or MASW measurements can provide the needed data. Using a theoretical soil structure, we show which parts of the ellipticity curve have to be included in the inversion process to get a reliable result and which parts can be omitted. Furthermore, the use of autocorrelation or high-frequency dispersion curves will be highlighted. The resulting guidelines for inversions including ellipticity data are then applied to real data measurements collected at 14 different sites during the European NERIES project. It is found that the results are in good agreement with dispersion curve measurements. Furthermore, the method can help in identifying the mode of Rayleigh waves in dispersion curve measurements.
    Description: Published
    Description: 207-229
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Inverse theory Surface waves and free oscillations Site effects Computational seismology Wave propagation ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2021-04-07
    Description: Stable isotopes were measured in the carbonate and organic matter of palaeosols in the Somma–Vesuvius area, southern Italy in order to test whether they are suitable proxy records for climatic and ecological changes in this area during the past 18000 yr. The ages of the soils span from ca. 18 to ca. 3 kyr BP. Surprisingly, the Last Glacial to Holocene climate transition was not accompanied by significant change in d18O of pedogenic carbonate. This could be explained by changes in evaporation rate and in isotope fractionation between water and precipitated carbonate with temperature, which counterbalanced the expected change in isotope composition of meteoric water. Because of the rise in temperature and humidity and the progressive increase in tree cover during the Holocene, the Holocene soil carbonates closely reflect the isotopic composition of meteoric water. A cooling of about 2°C after the Avellino eruption (3.8 ka) accounts for a sudden decrease of about 1‰ in d18O of pedogenic carbonate recorded after this eruption. The d13C values of organic matter and pedogenic carbonate covary, indicating an effective isotope equilibrium between the organic matter, as the source of CO2, and the pedogenic carbonate. Carbon isotopes suggest prevailing C3 vegetation and negligible mixing with volcanogenic or atmospheric CO2.
    Description: Published
    Description: 813-824
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: JCR Journal
    Description: restricted
    Keywords: stable isotope ; palaeosols ; Somma–Vesuvius ; palaeoclimate ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2021-06-22
    Description: Operative seismic aftershock risk forecasting can be particularly useful for rapid decision-making in the presence of an ongoing sequence. In such a context, limit state first-excursion probabilities (risk) for the forecasting interval (a day) can represent the potential for progressive state of damage in a structure. This work lays out a performance-based framework for adaptive aftershock risk assessment in the immediate post-mainshock environment. A time-dependent structural performance variable is adopted in order to measure the cumulative damage in a structure. A set of event-dependent fragility curves as a function of the first-mode spectral acceleration for a prescribed limit state is calculated by employing back-to-back non- linear dynamic analyses. An epidemic-type aftershock sequence model is employed for estimating the spatio-temporal evolution of aftershocks. The event-dependent fragility curves for a given limit state are then integrated together with the probability distribution of aftershock spectral acceleration based on the epidemic-type aftershock sequence aftershock hazard. The daily probability of limit state first-excursion is finally calculated as a weighted combination of the sequence of limit state probabilities conditioned on the num- ber of aftershocks. As a numerical example, daily aftershock risk is calculated for the L’Aquila 2009 aftershock sequence (central Italy). A representative three-story reinforced concrete frame with infill panels, which has cyclic strength and stiffness degradation, is used in order to evaluate the progressive damage. It is observed that the proposed framework leads to a sound forecasting of limit state first-excursion in the structure for two limit states of significant damage and near collapse. Copyright © 2014 John Wiley & Sons, Ltd.
    Description: Published
    Description: 2179–2197
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: aftershock ; time-dependent reliability ; seismic risk ; etas modeling ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Wiley-Blackwell
    In:  EPIC3Harmful Algal Blooms: A Compendium Desk Reference, Wiley-Blackwell, 12 p., pp. 563-574, ISBN: 978-1-118-99465-8
    Publication Date: 2018-06-28
    Description: The genus Alexandrium (Halim) is perhaps the most intensively studied among toxic marine dinoflagellates. This is largely attributable to the devastating consequences of toxigenic blooms of this genus, with human poisonings from contaminated seafood, primarily from shellfish and more rarely from finfish; socio–economic losses to the aquaculture and fisheries industries; marine faunal mortalities; and food web disruptions common in coastal waters throughout the world. Members of this genus are globally distributed from the Arctic to the tropics, and in both hemispheres from sub–polar through temperate to sub–tropical to tropicalwaters. At least four distinct groups of marine phycotoxins are associated with various Alexandrium species, along with poorly characterized bioactive compounds (allelochemicals) that may affect species interactions among the plankton. According to the most recent iteration of the IOC–UNESCO reference list of toxic microalgae, there are now more than 30 recognized morphological species of Alexandrium, posing a daunting challenge for risk assessment and accurate identification in toxic phytoplankton monitoring programs.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 8
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    Wiley-Blackwell
    In:  EPIC3Climate Change Impacts on Fisheries and Aquaculture: A Global Analysis, Climate Change Impacts on Fisheries and Aquaculture: A Global Analysis, Wiley-Blackwell, pp. 663-701, ISBN: 978-1-119-15404-4
    Publication Date: 2017-10-09
    Description: Exploitation of Southern Ocean marine resources began more than 200 years ago with the massive hunt for seals and whales. In the 1960s/70s, fisheries for finfish and krill entered Southern Ocean waters. Within a few years many fish populations were heavily overfished and dramatically depleted, and some of these stocks still did not recover. Today, fish stocks and fisheries activities are managed and monitored by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) which was established in 1982 to ensure sustainable exploitation and protection of the delicate marine ecosystem. Current target species include Mackerel icefish (Champsocephalus gunnari), Patagonian as well as Antarctic toothfish (Dissostichus eleginoides and D. mawsoni) and Antarctic krill (Euphausia superba). Most of these species are vulnerable to overfishing due to slow growth, late age at maturity, and rather low fecundity. This vulnerability might increase, as Southern Ocean living communities are currently also faced with alterations of their environment due to climate change, such as increasing water temperatures and decreasing sea ice. Species, including the ones targetted by fisheries, are well-adapted to their particular environmental conditions and are believed to be highly sensitive to changes because of their cold-adapted physiology, their life history traits, and their direct or indirect dependence on sea ice. The species will be exposed to several stressors at the same time, and fishing pressure, direct abiotic forcing and changes mediated via the food web might act synergistically and result in significant population declines. In particular the strongly sea ice-dependent Antarctic krill, a key species in the food web, might be adversely affected. Fish species seems to have low tolerance towards higher water temperatures and may thus, in the long run, be replaced by lower latitude species.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 9
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    Wiley-Blackwell
    In:  EPIC3Harmful Algal Blooms: A Compendium Desk Reference, Wiley-Blackwell, 8 p., pp. 605-612, ISBN: 978-1-118-99465-8
    Publication Date: 2018-06-28
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 10
    Publication Date: 2017-04-04
    Description: The Pernicana Fault (PF) is the main structural element of Mt Etna and the northern boundary of a section sliding to the southeast. Observed ground motion records in the damage zone of the PF show strong variations of directional resonance in the horizontal plane. The observed resonance directions exhibit an abrupt rotation of azimuth by about 30◦ across the fault, varying from N166◦ on the north side to N139◦ on the south. We interpret the directional resonance observations in terms of changes in the kinematics and deformation fields on the opposite sides of the fault. The northern side is affected primarily by the left-lateral strike-slip movement, whereas the southern side, that is subjected also to sliding, is under a dominant extensional stress regime. Brittle deformation models based on the observed kinematic field predict different sets of fractures on the opposite sides of the fault: synthetic cleavages and extensional fractures are expected to dominate in the northern and southern sides, respectively. These two fracture fields have different orientations (N74◦ and N42◦, respectively) and both show a near-orthogonal relation (∼88◦ in the northern sector and ∼83◦ to the south) with the azimuth of the observed directional resonance. We conclude that the direction of the largest resonance motions is sensitive to and has transversal relationship with the dominant fracture orientation. The directional amplification is inferred to be produced by stiffness anisotropy of the fault damage zone, with larger seismic motions normal to the fractures.
    Description: Published
    Description: 986–996
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake ground motions; Site effects; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2017-04-04
    Description: We consider a seismicity forecast experiment conducted during the last 4 yr. At the beginning of each year, three models make a 1-yr forecast of the distribution of large earthquakes everywhere on the Earth. The forecasts are generated and the observations are collected in the Collaboratory for the Study of Earthquake Predictability (CSEP). We apply CSEP likelihood measures of consistency and comparison to see how well the forecasts match the observations, and we compare results from some intuitive reference models. These results illustrate some undesirable properties of the consistency tests: the tests can be extremely sensitive to only a few earthquakes, and yet insensitive to seemingly obvious flaws—a na ̈ıve hypothesis that large earthquakes are equally likely everywhere is not always rejected. The results also suggest that one should check the assumptions of the so-called T and W comparison tests, and we illustrate some methods to do so. As an extension of model assessment, we explore strategies to combine forecasts, and we discuss the implications for operational earthquake forecasting. Finally, we make suggestions for the next generation of global seismicity forecast experiments.
    Description: Published
    Description: 422-431
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: probabilistic forecasting ; statistical seismology ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: The M ∼ 7 1915 Fucino (Central Italy) earthquake represents one of the most destructive seismic events ever occurred in the Italian Peninsula. Several seismogenic faults have been proposed in the past decades as the source of the earthquake by means of different approaches and techniques that lead to a variety of speculations about the source mechanism and the fault location, often contrasting with one another. The 1915 earthquake produced a remarkable data set of 73 coseismic hydrological changes in the near and intermediate field that consist in variation of the flow of streams and springs, liquefaction, rise of water temperature and turbidity. In this paper, we study the coseismic water level changes induced by the 1915 earthquake in the near field to provide convincing clues on the geometry of the earthquake causative fault. We model the coseismic strain field induced by seventeen individual faults proposed through different approaches, and compare its pattern with the distribution of streamflow changes. We find: (i) clues on the most probable geometry of the earthquake causative fault. Best fits between modelled deformation and observed data are displayed by sources (derived by geological or seismological data) that share several distinctive features, as they are ∼135◦-striking, SW-dipping, 25–30-km-long normal faults located along the eastern side of the Fucino basin. These data point to the Serrone Fault and the Parasano Fault as the most likely causative structures and support the hypothesis that the coseismic ruptures observed in the field represented primary surface faulting. On the contrary, our calculations show that the Pescina Fault and the Ventrino Fault are secondary faults from the perspective of the hydrological response. Finally, one of the best scoring potential sources (from geological data) is a multifaulting system that considers the presence, in the central-western part of the basin, of fault splays synthetic and antithetic to the main seismogenic structures; therefore, we infer for these splays a possible active involvement in a 1915-like seismogenic process; (ii) evidence against a number of seismogenic structures that were previously associated with the earthquake. In particular, the plots of coseismic strain induced by sources uniquely derived by macroseismic or geodetic data prove to be inconsistent with the polarities of the hydrological signatures. Also, sources mainly characterized by reverse faulting and/or by right-lateral strike-slip component are discarded and (iii) as a final remark, we maintain that the study of the hydrological signatures of earthquake strain can offer an alternative tool in the investigation of the historical seismicity, to estimate the focal mechanism of major earthquakes capable of giving rise to a consistent data set of hydrological data.
    Description: Published
    Description: 1374-1388
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: 1915 Fucino earthquake ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2017-04-04
    Description: Macroseismic intensities are the only available data for most historical earthquakes and often represent the unique source of information for crucial events in the definition of seismic hazard. In this paper, we attempt at getting insight into source characteristics by reproducing the observed intensity field. As a test case, we study the source of 1908 Messina Straits earthquake ( M W = 7.1), by testing three distinct fault models deduced from the analysis of geodeticdata.Startingfromthestaticslipdistribution,wedevelop kinematicsourcemodelsfor the investigated fault and compute full waveform synthetic seismograms in a 1-D structural model, also accounting for anelastic attenuation. Then, we convert both computed peak- ground acceleration (PGA) and peak-ground velocity (PGV) to macroseismic intensity at 100 selected sites, by means of specific empirical relations for the Italian region. By comparing the original data separately with PGA- and PGV-based intensity fields, we discriminate among the tested faults and determine the best values for the investigated kinematic parameters of the source. We also perform a misfit analysis for the best source model, in order to investigate the dependence of the results on the selected parametrization. The results of the analysis indicate that among the tested models, the one characterized by an east-dipping fault, with strike- oriented NS slightly rotated clockwise, better explains the observed macroseismic field of the 1908 Messina Straits earthquake. Besides, the fracture nucleated at the southern end of the fault and ruptured northward, producing considerable directivity effects. This is in agreement with the published results obtained from the investigation of the historical seismograms. We alsodeterminerealisticvalues fortherupturevelocityand therise-time.Ourstudyconfirms the greatpotentialofthemacroseismicdata,demonstratingthattheycontainenoughinformationto constrain important characteristics of the fault, which can be retrieved by using complex source models and computing complete wavefield. Moreover, we also show that the simultaneous comparison of both PGA- and PGV-based synthetic macroseismic fields with the original intensities provides tighter constraints for discriminating among different source models, with respect to what attainable from each of them
    Description: Published
    Description: 164-173
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake ground motions; Earthquake source observations. ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: Gravity and height changes, reflecting magma accumulation in subsurface chambers, are evaluated using Finite Element models in order to resolve controversial relationships observed in some volcanic areas. When significant gravity changes occur without any significant deformation, or vice versa, it is often difficult, if not impossible, to jointly explain the observations using the popular Mogi model. Here we explore whether these discrepancies can be explained by magma compressibility and source geometry effects. Compression of resident magma and expansion of the chamber wall act concurrently to accommodate newly added magma. Gravity-height ratios are found to mainly depend on: (i) geometry of the sources, which control the volume expansion of the chamber, (ii) magma compressibility, which affects the contraction of the magma resident in the chamber, and (iii) depth of the sources. Our numerical results show that, when magma compressibility and non-spherical sources are taken into account, significant gravity variations can, indeed, be successfully reconciled with negligible height changes. This may be the case at Etna volcano, where gravity changes (about 40 miuGal) without any significant deformation (below 5 cm) were observed during the 1994-1995 inflation period. The numerical results point to the accumulation of a 1.4x10^10 kg mass into an elongated source simulating a shallow storage region supplying the summit craters.
    Description: Published
    Description: 164-173
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: numerical modeling, gravity and height changes ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: We present an up-to-date high resolution picture of the ongoing crustal deformation field of Italy, based on an extensive combination of permanent and non-permanent GPS observations carried out since 1994. In addition, we present an updated map of contemporary SHmax orientations computed by a multidisciplinary data set of well-constrained stress indicators, including both published results and novel analyses. The comparison of stress and geodetic strain-rates directions reveals that both patterns are near-parallel over a large part of the investigated area, highlighting that crustal stress and surface deformation are driven by the same mechanism. The comparison of the azimuthal patterns of surface strain and mantle deformation shows a modest correlation on the Alps and a low correlation along the Apennines chain and the Calabro-Peloritan Arc. Along the Apennines chain, this feature suggests the occurrence of significant strain partitioning and crust–mantle mechanical decoupling. Along the Calabro-Peloritan Arc, the apparent low correlation reflects a different mantle–crust mechanism of deformation to the ongoing subduction and rollback of the Ionian slab. In addition, the superposition of regional/local effects related to second-order sources (crustal lateral density changes, strength contrasts), which at regional/local scale modulate the crustal stress/strain-rate pattern, cannot be ruled out.
    Description: Published
    Description: 969-985
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Plate motions ; Seismic anisotropy ; Kinematics of crustal and mantle deformation ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2017-04-04
    Description: In the Umbria Marche (Central Italy) region an important earthquake sequence occurred in 1997, characterized by nine earthquakes with magnitudes in the range between 5 and 6, that caused important damages and causalities. In the present paper we separately estimate intrinsic- and scattering- Q −1 parameters, using the classical MLTWA approach in the assumption of a half space model. The results clearly show that the attenuation parameters Qi −1 and Qs −1 are frequency dependent. This estimate is compared with other attenuation studies carried out in the same area, and with all the other MLTWA estimates obtained till now in other tectonic environments in the Earth. The bias introduced by the half space assumption is investigated through numerical solutions of the Energy Transport equation in the more realistic assumption of a heterogeneous crust overlying a transparent mantle, with a Moho located at a depth ranging between 35 and 45 km below the surface. The bias introduced by the half space assumption is significant only at high frequency. We finally show how the attenuation estimates, calculated with different techniques, lead to different PGA decay with distance relationships, using the well known and well proven Boore’s method. This last result indicates that care must be used in selecting the correct estimate of the attenuation parameters for seismic risk purposes. We also discuss the reason why MLTWA may be chosen among all the other available techniques, due to its intrinsic stability, to obtain the right attenuation parameters.
    Description: Published
    Description: 1370-1382
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: open
    Keywords: Seismic attenuation ; scattering ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2017-04-04
    Description: Seismological, geological and geodetic data have been integrated to characterize the seismogenic structure of the late 2013-early 2014 moderate energy (maximum local magnitude MLmax = 4.9) seismic sequence that struck the interior of the Matese Massif, part of the Southern Apennines active extensional belt. The sequence, heralded by a ML = 2.7 foreshock, was characterized by two main shocks with ML = 4.9 and ML = 4.2, respectively, which occurred at a depth of ∼17–18 km. The sequence was confined in the 10–20 km depth range, significantly deeper than the 1997–1998 sequence which occurred few km away on the northeastern side of the massif above ∼15 km depth. The depth distribution of the 2013–14 sequence is almost continuous, albeit a deeper (16–19 km) and a shallower (11–15 km) group of events can be distinguished, the former including the main shocks and the foreshock. The epicentral distribution formed a ∼10 km long NNW–SSE trending alignment, which almost parallels the surface trace of late Pliocene–Quaternary southwest-dipping normal faults with a poor evidence of current geological and geodetic deformation. We built an upper crustal model profile for the eastern Matese massif through integration of geological data, oil exploration well logs and seismic tomographic images. Projection of hypocentres on the profile suggests that the seismogenic volume falls mostly within the crystalline crust and subordinately within the Mesozoic sedimentary cover of Apulia, the underthrust foreland of the Southern Apennines fold and thrust belt. Geological data and the regional macroseismic field of the sequence suggest that the southwest-dipping nodal plane of the main shocks represents the rupture surface that we refer to here as the Matese fault. The major lithological discontinuity between crystalline and sedimentary rocks of Apulia likely confined upward the rupture extent of the Matese fault. Repeated coseismic failure represented by the deeper group of events in the sequence, activated in a passive fashion the overlying ∼11–15 km deep section of the upper crustal normal faults. We consider the southwest-dipping Matese fault representative of a poorly known type of seismogenic structures in the Southern Apennines, where extensional seismogenesis and geodetic strain accumulation occur more frequently on NE-dipping, shallower-rooted faults. This is the case of the Boiano Basin fault located on the northern side of the massif, to which the 1997–1998 sequence is related. The close proximity of the two types of seismogenic faults at the Matese Massif is related to the complex crustal architecture generated by the Pliocene–early Pleistocene contractional and transpressional tectonics.
    Description: Published
    Description: 823-837
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: partially_open
    Keywords: Seismicity and tectonics ; Continental tectonics: extensional ; Crustal structure ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2017-04-04
    Description: We analysed the conversion problem between teleseismic magnitudes (Ms and mb) provided by the Seismological Bulletin of the International Seismological Centre and moment magni- tudes (Mw) provided by online moment tensor (MT) catalogues using the chi-square general orthogonal regression method (CSQ) that, differently from the ordinary least-square regres- sion method (OLS), accounts for the measurement errors of both the predictor and response variables. To account for the non-linearity of the relationships, we used two types of curvilin- ear models: (i) the exponential model (EXP), recently proposed by the authors of the Global Catalogue sponsored by the Global Earthquake Model (GEM) Foundation and (ii) a connected bilinear (CBL) model, similar to that proposed by Ekstro ̈m & Dziewonski, where two different linear trends at low and high magnitudes are connected by an arc of circle that preserves the continuity of the function and of its first derivative at the connecting points. For Ms, we found that the regression curves computed for a global data set (GBL) are likely to be biased by the incompleteness of global MT catalogues for Mw 〈5.0–5.5. In fact, the GBL curves deviate significantly from a similar regression curve computed for a Euro-Mediterranean data set (MED) integrated with the data provided by two regional MT catalogues including many more events with Mw 〈 5.0–5.5. The GLB regression curves overestimate the Mw proxies computed from Ms up to 0.5 magnitude units. Hence for computing Mw proxies at the global scale of Ms ≤ 5.5, we suggest to adopt the coefficients obtained from the MED regression. The analysis of the frequency–magnitude relationship of the resulting Mw proxy catalogues confirms the validity of this choice as the behaviour of b-value as a function of cut-off magnitude of the GBL data set is much more stable using such approach. The incompleteness of Mw’s provided from MT global catalogues also affects the mb GBL data set but in this case the use of the CSQ regression method, in place of the OLS, mitigates the bias and then, at low magnitudes, the EXP regression curve computed from the more complete MED data set almost coincides with that computed from the GBL data set. Our results also indicate that the slope at low magnitudes of the Mw–Ms relationship is substantially consistent with the hypothesized theoretical value of 2/3 for Ms 〈 5.0 while the slope of the Mw–mb relationship at high magnitudes probably reaches the theoretically expected value of 2 only in the proximity of the upper limit of mb determinations in our data set (mb = 7.2).
    Description: Published
    Description: 805–828
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations ; Statistical seismology ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: In a recent paper, important issues were raised about the identification of the fault responsible for the 1908 Messina Straits earthquake. Starting with a reanalysis of the available original geodetic data, the authors aimed to demonstrate that both of the fault–plane orientations derived by the focal mechanism are compatible with the measurements. On these grounds, and based on geological considerations, they argued in favour of the Armo fault—a high-angled structure on the Calabrian side of the Messina Straits—as responsible for the 1908 earthquake. We indicate here that their analysis has some pitfalls that produce questionable results, and that render their conclusions unreliable. Moreover, especially when dealing with such old events and data, we consider that it is more prudent not to derive conclusions on the basis of a single data set, as all of the available information should be included in any interpretation. Indeed, when the joint results of the seismological and geodetic analyses are taken into account, a consistent and robust source model can be derived that indicates that a low-angle, east-dipping fault is the most likely source of this 1908 Messina Straits earthquake
    Description: Published
    Description: 1399-1402
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations; Seismicity and tectonics; Europe ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2017-04-04
    Description: In this study,we use Differential Synthetic Aperture Radar Interferometry (DInSAR) and multiaperture interferometry (MAI) to constrain the sources of the three largest events of the 2008 Baluchistan (western Pakistan) seismic sequence, namely two Mw 6.4 events only 12 hr apart and an Mw 5.7 event that occurred 40 d later. The sequence took place in the Quetta Syntaxis, the most seismically active region of Baluchistan, tectonically located between the colliding Indian Plate and the Afghan Block of the Eurasian Plate. Surface displacements estimated from ascending and descending ENVISAT ASAR acquisitions were used to derive elastic dislocation models for the sources of the two main events. The estimated slip distributions have peak values of 120 and 130 cm on a pair of almost parallel and near-vertical faults striking NW–SE, and of 50 cm and 60 cm on two high-angle faults striking NE–SW. Values up to 50 cm were found for the largest aftershock on an NE–SW fault located between the sources of the main shocks. The MAI measurements, with their high sensitivity to the north–south motion component, are crucial in this area to accurately describe the coseismic displacement field. Our results provide insight into the deformation style of the Quetta Syntaxis, suggesting that right-lateral slip released at shallow depths on large NW fault planes is compatible with left-lateral activation on smaller NE–SW faults.
    Description: Published
    Description: 25-39
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Radar interferometry ; Satellite geodesy ; Seismicity and Tectonics ; Continental margins: convergent ; Earthquake interaction, forecasting and prediction ; Earthquake source observation ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
    Publication Date: 2017-04-04
    Description: The relative seismic velocity variations possibly associated to large earthquakes can be readily monitored via cross-correlation of seismic noise. In a recently published study, more than 2 yr of continuous seismic records have been analysed from three stations surrounding the epicentre of the 2009 April 6, Mw 6.1 L’Aquila earthquake, observing a clear decrease of seismic velocities likely corresponding to the co-seismic shaking. Here, we extend the analysis in space, including seismic stations within a radius of 60 km from the main shock epicentre, and in time, collecting 5 yr of data for the six stations within 40 km of it. Our aim is to investigate how far the crustal damage is visible through this technique, and to detect a potential post-seismic recovery of velocity variations. We find that the co-seismic drop in velocity variations extends up to 40 km from the epicentre, with spatial distribution (maximum around the fault and in the north– east direction from it) in agreement with the horizontal co-seismic displacement detected by global positioning system (GPS). In the first few months after L’Aquila earthquake, the crust’s perturbation in terms of velocity variations displays a very unstable behaviour, followed by a slow linear recovery towards pre-earthquake conditions; by almost 4 yr after the event, the co-seismic drop of seismic velocity is not yet fully recovered. The strong oscillations of the velocity changes in the first months after the earthquake prevent to detect the fast exponential recovery seen by GPS data. A test of differently parametrized fitting curves demonstrate that the post-seismic recovery is best explained by a sum of a logarithmic and a linear term, suggesting that processes like viscoelastic relaxation, frictional afterlip and poroelastic rebound may be acting concurrently.
    Description: Published
    Description: 604-6011
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: Time-series analysis; Interferometry; Computational seismology; Europe ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
    Publication Date: 2019-12-13
    Description: Downtown L'Aquila suffered severe damage (VIII-IX EMS98 intensity) during the 2009 April 6 Mw 6.3 earthquake. The city is settled on a top flat hill, with a shear-wave velocity profile characterized by a reversal of velocity at a depth of the order of 50–100 m, corresponding to the contact between calcareous breccia and lacustrine deposits. In the southern sector of downtown, a thin unit of superficial red soils causes a further shallow impedance contrast that may have influenced the damage distribution during the 2009 earthquake. In this paper, the main features of ambient seismic vibrations have been studied in the entire city centre by using array measurements. We deployed six 2-D arrays of seismic stations and 1-D array of vertical geophones. The 2-D arrays recorded ambient noise, whereas the 1-D array recorded signals produced by active sources. Surface-wave dispersion curves have been measured by array methods and have been inverted through a neighbourhood algorithm, jointly with the H/V ambient noise spectral ratios related to Rayleigh waves ellipticity. We obtained shear-wave velocity (Vs) profiles representative of the southern and northern sectors of downtown L'Aquila. The theoretical 1-D transfer functions for the estimated Vs profiles have been compared to the available empirical transfer functions computed from aftershock data analysis, revealing a general good agreement. Then, the Vs profiles have been used as input for a deconvolution analysis aimed at deriving the ground motion at bedrock level. The deconvolution has been performed by means of EERA and STRATA codes, two tools commonly employed in the geotechnical engineering community to perform equivalent-linear site response studies. The waveform at the bedrock level has been obtained deconvolving the 2009 main shock recorded at a strong motion station installed in downtown. Finally, this deconvolved waveform has been used as seismic input for evaluating synthetic time-histories in a strong-motion target site located in the middle Aterno river valley. As a target site, we selected the strong-motion station of AQV 5 km away from downtown L'Aquila. For this site, the record of the 2009 L'Aquila main shock is available and its surface stratigraphy is adequately known making possible to propagate the deconvolved bedrock motion back to the surface, and to compare recorded and synthetic waveforms.
    Description: Published
    Description: 848–866
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Fourier analysis, Earthquake ground motions , Site effects ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2020-05-27
    Description: We propose an innovative approach to mapping CMB topography from seismic P-wave trav- eltime inversions: instead of treating mantle velocity and CMB topography as independent parameters, as has been done so far, we account for their coupling by mantle flow, as formulated by Forte & Peltier. This approach rests on the assumption that P data are sufficiently sensitive to thermal heterogeneity, and that compositional heterogeneity, albeit important in localized regions of the mantle (e.g. within the D′′ region), is not sufficiently strong to govern the pattern of mantle-wide convection and hence the CMB topography. The resulting tomographic maps of CMB topography are physically sound, and they resolve the known discrepancy between images obtained from classic tomography on the basis of core-reflected and core-refracted seismic phases. Since the coefficients of mantle velocity structure are the only free parameters of the inversion, this joint tomography–geodynamics approach reduces the number of param- eters; nevertheless the corresponding mantle models fit the seismic data as well as the purely seismic ones.
    Description: Published
    Description: 730-746
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic tomography ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
    Publication Date: 2017-04-04
    Description: We present the results of palaeomagnetic analysis on Late Bronge Age pottery from Santorini carried out in order to estimate the thermal effect of the Minoan eruption on the pre-Minoan habitation level. A total of 170 specimens from 108 ceramic fragments have been studied. The ceramics were collected from the surface of the pre-Minoan palaeosol at six different sites, including also samples from the Akrotiri archaeological site. The deposition temperatures of the first pyroclastic products have been estimated by the maximum overlap of the re-heating temperature intervals given by the individual fragments at site level. A new statistical elaboration of the temperature data has also been proposed, calculating at 95 per cent of probability the re-heating temperatures at each site. The obtained results show that the precursor tephra layer and the first pumice fall of the eruption were hot enough to re-heat the underlying ceramics at temperatures 160–230 ◦C in the non-inhabited sites while the temperatures recorded inside the Akrotiri village are slightly lower, varying from 130 to 200 ◦C. The decrease of the temperatures registered in the human settlements suggests that there was some interaction between the buildings and the pumice fallout deposits while probably the buildings debris layer caused by the preceding and syn-eruption earthquakes has also contributed to the decrease of the recorded re-heating temperatures.
    Description: Published
    Description: 33-47
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Archaeomagnetism ; Rock and mineral magnetism ; Volcaniclastic deposits ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
    Publication Date: 2017-04-04
    Description: Probabilistic tsunami hazard analysis (PTHA) relies on computationally demanding numerical simulations of tsunami generation, propagation, and non-linear inundation on high-resolution topo-bathymetric models. Here we focus on tsunamis generated by co-seismic sea floor dis- placement, that is, on Seismic PTHA (SPTHA). A very large number of tsunami simulations are typically needed to incorporate in SPTHA the full expected variability of seismic sources (the aleatory uncertainty). We propose an approach for reducing their number. To this end, we (i) introduce a simplified event tree to achieve an effective and consistent exploration of the seismic source parameter space; (ii) use the computationally inexpensive linear approximation for tsunami propagation to construct a preliminary SPTHA that calculates the probability of maximum offshore tsunami wave height (H Max) at a given target site; (iii) apply a two-stage filtering procedure to these ‘linear’ SPTHA results, for selecting a reduced set of sources and (iv) calculate ‘non-linear’ probabilistic inundation maps at the target site, using only the selected sources. We find that the selection of the important sources needed for approximating probabilistic inundation maps can be obtained based on the offshore HMax values only. The filtering procedure is semi-automatic and can be easily repeated for any target sites. We describe and test the performances of our approach with a case study in the Mediterranean that considers potential subduction earthquakes on a section of the Hellenic Arc, three target sites on the coast of eastern Sicily and one site on the coast of southern Crete. The comparison between the filtered SPTHA results and those obtained for the full set of sources indicates that our approach allows for a 75–80 per cent reduction of the number of the numerical simulations needed, while preserving the accuracy of probabilistic inundation maps to a reasonable degree.
    Description: Published
    Description: 574-588
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Tsunami ; Hazard ; Probabilistic ; Subduction ; Mediterranean ; SPTHA ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
    Publication Date: 2017-04-04
    Description: Temporal variations in the elastic behaviour of the Earth’s crust can be monitored through the analysis of the Earth’s seismic response and its evolution with time. This kind of analysis is particularly interesting when combined with the reconstruction of seismic Green’s functions from the cross-correlation of ambient seismic noise, which circumvents the limitations imposed by a dependence on the occurrence of seismic events. In fact, because seismic noise is recorded continuously and does not depend on earthquake sources, these cross-correlation functions can be considered analogously to records from continuously repeating doublet sources placed at each station, and can be used to extract observations of variations in seismic velocities. These variations, however, are typically very small: of the order of 0.1 per cent. Such accuracy can be only achieved through the analysis of the full reconstructed waveforms, including later scattered arrivals. We focus on the method known as Moving-Window Cross-Spectral Analysis that has the advantage of operating in the frequency domain, where the bandwidth of coherent signal in the correlation function can be clearly defined. We investigate the sensitivity of this method by applying it to microseismic noise cross-correlations which have been perturbed by small synthetic velocity variations and which have been randomly contaminated. We propose threshold signal-to-noise ratios above which these perturbations can be reliably observed. Such values are a proxy for cross-correlation convergence, and so can be used as a guideline when determining the length of microseismic noise records that are required before they can be used for monitoring with the moving-window cross-spectral technique.
    Description: Published
    Description: 867-882
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: Interferometry; Volcano monitoring ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 27
    Publication Date: 2017-04-04
    Description: In this study we have investigated the forward directivity associated with the initial up-dip rupture propagation during the April 6th 2009 (MW 6.1) L’Aquila normal-faulting earthquake. The objective is the understanding of how the peculiar initial behavior of rupture history during the main shock has affected the near-source recorded ground motions in the L’Aquila town and surrounding areas. We have modeled the observed ground velocities at the closest near-source recording sites by computing synthetic seismograms using a discrete wavenumbers and finite difference approach in the low frequency bandwidth (0.02-0.4 Hz) to avoid site effects contaminations. We use both the rupture model retrieved by inverting ground motion waveforms and continuous high sampling-rate GPS time series as well as uniform-slip constant-rupture speed models. Our results demonstrate that the initial up-dip rupture propagation, characterizing the first three seconds of the rupture history during the L’Aquila main shock and releasing only ∼25% of total seismic moment, controls the observed ground motions in the near-source. This initial stage of the rupture is characterized by the generation of clear ground velocity pulses, which we interpret as a forward directivity effect. Our modeling results confirm a heterogeneous distribution of rupture velocity during the initial up-dip rupture propagation, since uniform rupture speed models overestimate up-dip directivity effects in the footwall of the causative fault. The up-dip directivity observed in the near field during the 2009 L’Aquila main shock is that predicted for a normal faulting earthquake by Somerville’s directivity model, but it differs from that inferred from far-field observations that conversely provide evidence of along-strike directivity. This calls for a careful analysis as well as for the realistic inclusion of rupture directivity to predict ground motions in the near source.
    Description: Published
    Description: 1618-1631
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: earthquake ground motion, earthquake source observations, computational seismology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
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    Unknown
    Wiley-Blackwell
    In:  Magnitude conversion problem using general orthogonal regression’ by H. R. Wason, Ranjit Das and M. L. Sharma, (Geophys. J. Int., 190, 1091–1096)
    Publication Date: 2017-04-04
    Description: The argument proposed by Wason et al. that the conversion of magnitudes from a scale (e.g. Ms or mb) to another (e.g. Mw), using the coefficients computed by the general orthogonal regression method (Fuller) is biased if the observed values of the predictor (independent) variable are used in the equation as well as the methodology they suggest to estimate the supposedly true values of the predictor variable are wrong for a number of theoretical and empirical reasons. Hence, we advise against the use of such methodology for magnitude conversions.
    Description: Published
    Description: 626-627
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations ; Statistical seismology ; Computational seismology ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 29
    facet.materialart.
    Unknown
    Wiley-Blackwell
    Publication Date: 2017-04-04
    Description: Fluids—essentially meteoric water—are present everywhere in the Earth’s crust, occasionally also with pressures higher than hydrostatic due to the tectonic strain imposed on impermeable undrained layers, to the impoundment of artificial lakes or to the forced injections required by oil and gas exploration and production. Experimental evidence suggests that such fluids flow along preferred paths of high diffusivity, provided by rock joints and faults. Studying the coupled poroelastic problem, we find that such flow is ruled by a nonlinear partial differential equation amenable to a Barenblatt-type solution, implying that it takes place in formof solitary pressure waves propagating at a velocity which decreases with time as v ∝t [1/(n − 1) − 1] with n 7. According to Tresca-Von Mises criterion, these waves appear to play a major role in earthquake triggering, being also capable to account for aftershock delay without any further assumption. The measure of stress and fluid pressure inside active faults may therefore provide direct information about fault potential instability.
    Description: Published
    Description: 1281–1285
    Description: 6T. Sismicità indotta e caratterizzazione sismica dei sistemi naturali
    Description: N/A or not JCR
    Description: restricted
    Keywords: forecasting and prediction ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 30
    Publication Date: 2017-04-04
    Description: Our improved capability to adapt to future changes in discharge is linked to our capability to predict the magnitude or at least the direction of these changes. For the agricultural U.S. Midwest, too much or too little water has severe socio-economic impacts. Here we focus on the Raccoon River at Van Meter, Iowa, and use a statistical approach to examine projected changes in discharge. We build on statistical models using rainfall and harvested corn and soybean acreage to explain the observed discharge variability. We then use projections of these two predictors to examine the projected discharge response. Results are based on seven global climate models part of the Coupled Model Intercomparison Project Phase 5 and two representative concentration pathways (RCPs 4.5 and 8.5). There is not a strong signal of change in the discharge projections under the RCP 4.5. However the results for the RCP 8.5 point to a stronger changing signal related to larger projected increases in rainfall, resulting in increasing trends in particular in the upper part of the discharge distribution (i.e., 60th percentile and above). Examination of two hypothetical agricultural scenarios indicates that these increasing trends could be alleviated by decreasing the extent of the agricultural production. We also discuss how the methodology presented in this study represents a viable approach to move forward with the concept of return period for engineering design and management in a non-stationary world.
    Description: Published
    Description: 1361–1371
    Description: 4A. Clima e Oceani
    Description: JCR Journal
    Description: restricted
    Keywords: river discharge ; rainfall ; statistical model ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
    Publication Date: 2017-04-04
    Description: We present a strategy to thoroughly investigate the effects of prominent topography on the surface tilt due to a spherical pressure source. We use Etna's topography as a case of study and, for different source positions, we compare the tilt fields calculated through (i) a 3-D boundary element method and (ii) analytical half-space solutions. We systematically determine (i) the source positions leading to the strongest tilt misfits when numerical and analytical results are compared and (ii) the surface areas where the strongest distortions in the tilt field are most likely to be observed. We also demonstrate that, under critical circumstances, in terms of respective positions of pressure source and observation points, results of inversion procedures aimed at retrieving the source parameters can be misleading, if tilt data are analysed using models that do not account for topography.
    Description: Published
    Description: 1471–1481
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Numerical approximations and analysis ; Transient deformation ; Volcano monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
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  • 32
    Publication Date: 2017-12-11
    Description: In this study we applied a multidisciplinary approach, coupling geophysical and geochemical measurements, to unveil the provenance of 170 obsidian flakes, collected on the volcanic island of Ustica (Sicily). On this island there are some prehistoric settlements dated from the Neolithic to the Middle Bronze Age. Despite not having geological outcrops of obsidian rocks, the countryside of Ustica is rich in fragments of this volcanic glass, imported from other source areas. The study of obsidian findings was carried out first through visual observations and density measurements. At least two different obsidian families have been distinguished, probably imported from Lipari and Pantelleria islands. Analysing the magnetic properties of the samples, these two main sources were confirmed, but the possibility of other provenances was inferred. Finally, we characterized the geochemical signature of the Ustica obsidians by performing microchemical analyses through electron microprobe (EMPA) and laser ablation (LA–ICP–MS). The results were compared with literature data, confirming the presence of the Lipari and Pantelleria sources (Sicily) and indicating for the first time in this part of Italy a third provenance from Palmarola island (Latium). Our results shed new light on the commercial exchanges in the peri-Tyrrhenian area during the prehistoric age.
    Description: Published
    Description: 435–454
    Description: 1SR. TERREMOTI - Servizi e ricerca per la Società
    Description: 2SR. VULCANI - Servizi e ricerca per la Società
    Description: 3SR. AMBIENTE - Servizi e ricerca per la Società
    Description: JCR Journal
    Description: restricted
    Keywords: obsdian provenance ; LA-ICPMS ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 33
    Publication Date: 2018-03-20
    Description: Our study area is a ~50 km long section of the central-southern Apennines tectonic belt that includes the Pergola-Melandro basin and the Agri valley. This region is located between the areas interested by the 1980 Ms=6.9 Irpinia and the 1857 M=7.0 Val d’Agri earthquakes and is characterized by rare historical events and very low and sparse background seismicity. In this study we provide new seismological and geophysical information to identify the characteristics of the seismotectonics in the area, as the prevailing faulting mechanism and the fit of local to regional stress field. These data concern focal mechanisms from waveform modeling and P-wave polarities, analyses of borehole breakouts and detailed investigation of two seismic sequences. All the data cover a significantly broad range of magnitudes and depths and suggest that no important local variation in stress orientation seems to affect this area, which shows a NE-SW direction of extension consistent with that regionally observed in Southern Italy. Such local homogeneity in the stress field pattern is peculiar of the study area; the variations of orientation and/or type of stress observed in the northern Apennines or only less than 100 km toward the northwest within the same tectonic belt are absent here. Furthermore, there is a suggestion for a northeastward sense of dip of the seismogenic faults in the region, an interesting constraint to the characterization of seismic sources
    Description: Published
    Description: 575-583
    Description: 2T. Sorgente Sismica
    Description: JCR Journal
    Keywords: faulting ; seismicity ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 34
    Publication Date: 2020-02-24
    Description: Metal-catalysed CO2 hydrogenation is considered a source of methane in serpentinized (hydrated) igneous rocks and a fundamental abiotic process germane to the origin of life. Iron, nickel, chromium and cobalt are the catalysts typically employed in hydrothermal simulation experiments to obtain methane at temperatures 〉200°C. However, land-based present-day serpentinization and abiotic gas apparently develop below 100°C, down to approximately 40–50°C. Here, we document considerable methane production in thirteen CO2 hydrogenation experiments performed in a closed dry system, from 20 to 90°C and atmospheric pressure, over 0.9–122 days, using concentrations of non-pretreated ruthenium equivalent to those occurring in chromitites in ophiolites or igneous complexes (from 0.4 to 76 mg of Ru, equivalent to the amount occurring approximately in 0.4–760 kg of chromitite). Methane production increased with time and temperature, reaching approximately 87 mg CH4 per gram of Ru after 30 days (2.9 mgCH4/gru/day) at 90°C. At room temperature, CH4 production rate was approximately three orders of magnitude lower (0.003 mgCH4/gru/day). We report the first stable carbon and hydrogen isotope ratios of abiotic CH4 generated below 100°C. Using initial d13CCO2 of -40&, we obtained room temperature d13CCH4 values as 13C depleted as 142&. With time and temperature, the C-isotope separation between CO2 and CH4 decreased significantly and the final d13CCH4 values approached that of initial d13CCO2. The presence of minor amounts of C2-C6 hydrocarbons is consistent with observations in natural settings. Comparative experiments at the same temperatures with iron and nichel catalysts did not generate CH4. Ru-enriched chromitites could potentially generate methane at low temperatures on Earth and on other planets.
    Description: Published
    Description: 438–452
    Description: 7A. Geofisica di esplorazione
    Description: JCR Journal
    Description: restricted
    Keywords: abiotic methane, Sabatier reaction ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 35
    Publication Date: 2020-02-05
    Description: In this paper, we present a method for handling uncertainties in the determination of the source parameters of earthquakes from spectral data. We propose a robust framework for estimating earthquake source parameters and relative uncertainties, which are propagated down to the estimation of basic seismic parameters of interest such as the seismic moment, the moment magnitude, the source size and the static stress drop. In practice, we put together a Bayesian approach for model parameter estimation and a weighted statistical mixing of multiple solutions obtained from a network of instruments, providing a useful framework for extracting meaningful data from intrinsically uncertain data sets. The Bayesian approach used to estimate the source spectra parameters is a simple but powerful mechanism for non-linear model fitting, providing also the opportunity to naturally propagate uncertainties and to assess the quality and uniqueness of the solution. Another important added value of such an approach is the possibility of integrating information from the expertise of seismologists. Such data can be encoded in a prior state of information that is then updated with the information provided by seismological data. The performance of the proposed approach is demonstrated analysing data from the 1909 April 23 earthquake occurred near Benavente (Portugal).
    Description: Published
    Description: 691-701
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Fourier analysis ; Probability distributions ; Earthquake source observations ; Seismicity and tectonics ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 36
    Publication Date: 2017-04-04
    Description: The elevation of the Capo Vaticano coastal terraces (Tyrrhenian coast, central Calabria) is the result of a combination of regional uplift and repeated coseismic displacement. We subtract the regional uplift from the total uplift (maximum average uplift rates: 0.81–0.97 mm a)1 since c. 0.7 Ma) and obtain the residual fault-related displacement. Then, we model the residual displacement to provide constraints on the location and geometry of the seismogenic source of the 1905 M7 earthquake, the strongest – and still poorly understood – earthquake of the instrumental era in this area. We try four different potential sources for the dislocation modelling and find that (1) three sources are not compatible with the displacement observed along the terraces and (2) the only source consistent with the local deformation is the 100 - striking Coccorino Fault. We calculate average long-term vertical slip rates of 0.2–0.3 mm a)1 on the Coccorino Fault and estimate an average recurrence time of one millennium for a 1905-type earthquake.
    Description: Published
    Description: 378-389
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: 1905 earthquake ; marine terraces ; coseismic displacement ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
    Publication Date: 2017-04-04
    Description: Real-time seismology has made significant improvements in recent years, with source parameters now available within a few tens of minutes after an earthquake. It is likely that this time will be further reduced, in the near future, by means of increased efficiency in real-time transmission,increasingdatacoverageandimprovementofthemethodologies.Inthiscontext, together with the development of new ground motion predictive equations (GMPEs) that are abletoaccountforsourcecomplexity,thegenerationofstronggroundmotionshakingmapsin quasi-real time has become ever more feasible after the occurrence of a damaging earthquake. However, GMPEs may not reproduce reliably the ground motion in the near-source region where the finite fault parameters have a strong influence on the shaking. Inthispaperwetestwhetheraccountingforsource-relatedeffectsiseffectiveinbettercharacterizingthegroundmotion.WeintroduceamodificationoftheGMPEswithintheShakeMap softwarepackage,andsubsequentlytesttheaccuracyofthenewlygeneratedshakemapsinpredictingthegroundmotion.ThetestisconductedbycontrollingtheperformanceofShakeMap as we decrease the amount of the available information. We then update ShakeMap with the GMPE modified with a corrective factor accounting for source effects, in order to better constrain these effects that likely influence the level of (near-source) ground shaking. Weinvestigatetwowell-recordedearthquakesfromJapan(the2000Tottori, Mw 6.6,andthe 2008 Iwate-Miyagi, Mw7.0, events) where the instrumental coverage is as dense as needed to ensure an objective appraisal of the results. The results demonstrate that the corrected GMPE can capture only some aspects of the ground shaking in the near-source area, neglecting other multidimensional effects, such as propagation effects and local site amplification.
    Description: Italian Presidenza del Consiglio dei Ministri, Dipartimento della Protezione Civile(DPC)under the contract 2007–2009 DPC-INGVS3project
    Description: Published
    Description: 1836-1848
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake ground motions ; Earthquake source observation ; Computational seismology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
    Publication Date: 2017-04-04
    Description: A recent study of the Matuyama–Brunhes (M-B) geomagnetic field reversal recorded in exposed lacustrine sediments from the Sulmona Basin (Italy) provided a continuous, highresolution record indicating that the reversal of the field direction at the terminus of the M-B boundary (MBB) occurred in less than a century, about 786 ka ago. In the sediment, thin (4–6 cm) remagnetized horizons were recognized above two distinct tephra layers—SUL2- 19 and SUL2-20—that occur ∼25 and ∼35 cm below the MBB, respectively. Also, a faint, millimetre-thick tephra (SUL2-18) occurs 2–3 cm above the MBB.With the aim of improving the temporal resolution of the previous Sulmona MBB record and understanding the possible influence of cryptotephra on the M-B record in the Sulmona Basin,we performed more detailed sampling and analyses of overlapping standard and smaller samples from a 50 cm-long block that spans the MBB. The new data indicate that (i) the MBB is even sharper than previously reported and occurs ∼2.5 cm below tephra SUL2-18, in agreement with the previous study; (ii) the MBB coincides with the rise of an intensity peak of the natural remanent magnetization (NRM) intensity, which extends across SUL2-18; (iii) except for a 2-cm-thick interval just above tephra SUL2-18, the rock magnetic parameters (k, ARM, Mr, Ms, Bc, Bcr) indicate exactly the same magnetic mineralogy throughout the sampled sequence. We conclude that either SUL2-18 resulted in the remagnetization of an interval of about 6 cm (i.e. during the NRM intensity peak spanning ∼260 ± 110 yr, according to the estimated local sedimentation rate), and thus the detailed MBB record is lost because it is overprinted, or the MBB is well recorded, occurred abruptly about 2.5 cm below SUL2-18 and lasted less than 13 ± 6 yr. Both hypotheses challenge our understanding of the geomagnetic field behaviour during a polarity transition and/or of the NRM acquisition process in the Sulmona lacustrine sediment.
    Description: Published
    Description: 798-812
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Palaeomagnetic secular variation; Rapid time variations; Reversals: process, time scale, magnetostratigraphy; Rock and mineral magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
    Publication Date: 2021-11-25
    Description: On 2012 May 20 and 29, two damaging earthquakes with magnitudes Mw 6.1 and 5.9, respectively, struck the Emilia-Romagna region in the sedimentary Po Plain, Northern Italy, causing 26 fatalities, significant damage to historical buildings and substantial impact to the economy of the region. The earthquake sequence included four more aftershocks with Mw ? 5.0, all at shallow depths (about 7–9 km), with similar WNW–ESE striking reverse mechanism. The timeline of the sequence suggests significant static stress interaction between the largest events. We perform here a detailed source inversion, first adopting a point source approximation and considering pure double couple and full moment tensor source models. We compare different extended source inversion approaches for the two largest events, and find that the rupture occurred in both cases along a subhorizontal plane, dipping towards SSW. Directivity is well detected for the May 20 main shock, indicating that the rupture propagated unilaterally towards SE. Based on the focal mechanism solution, we further estimate the co-seismic static stress change induced by the May 20 event. By using the rate-and-state model and a Poissonian earthquake occurrence, we infer that the second largest event of May 29 was induced with a probability in the range 0.2–0.4. This suggests that the segment of fault was already prone to rupture. Finally, we estimate peak ground accelerations for the two main events as occurred separately or simultaneously. For the scenario involving hypothetical rupture areas of both main events, we estimate Mw = 6.3 and an increase of ground acceleration by 50 per cent. The approach we propose may help to quantify rapidly which regions are invested by a significant increase of the hazard, bearing the potential for large aftershocks or even a second main shock.
    Description: Published
    Description: 1658-1672
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake dynamics ; Earthquake source observations ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
    Publication Date: 2022-05-24
    Description: Close relationships between deformation and volcanism are well documented in relatively late evolutionary stages of con- tinental rifting, whereas these are poorly constrained in less mature rifting stages. To investigate the control of inherited structures on faulting and volcanism, we present a statistical analysis of volcanic features, faults and pre-rift fabric in the Tanzania Divergence, where volcanic features occur exten- sively in in-rift and off-rift areas. Our results show that in mature rift sectors (Natron), magma uprising is mostly con- trolled by fractures/faults responding to the far-field stress, whereas the distribution of volcanism during initial rifting (Eyasi) is controlled by inherited structures oblique to the regional extension direction. Off-rift sectors show a marked control of pre-rift structures on magma emplacement, which may not respond to the regional stress field. Thus, the use of off-rift magmatic features as stress indicators should take into account the role of pre-existing structures.
    Description: Published
    Description: 461-468
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: East Africa Rift System, Tanzania-Kenia, structures and volcanism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
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    Canadian Science Publishing
    In:  EPIC3Arctic Science, Canadian Science Publishing, 2(2), pp. 33-49, ISSN: 2368-7460
    Publication Date: 2022-08-12
    Description: Manual collection of accurate phenology data is time-consuming and expensive. In this study, we investigate whether repeat colour digital photography can be used (1) to identify phenological patterns, (2) to identify differences in vegetation due to experimental warming and site moisture conditions, and (3) as a proxy for biomass. Pixel values (RGB) were extracted from images taken of permanent plots in long-term warming experiments in three tundra communities at a high Arctic site during one growing season. The Greenness Excess Index (GEI) was calculated from image data at the plot scale (1 × 1 m) as well as for two species, Dryas integrifolia and Salix arctica. GEI values were then compared to corresponding field-based phenology observations. GEI and Normalized Difference Vegetation Index (NDVI) values from a paired set of true colour and infrared images were compared with biomass data. The GEI values followed seasonal phenology at the plot and species scale and correlated well with standardized observations. GEI correlated well with biomass and was able to detect quantitative differences between warmed and control plots and the differences between communities due to site-specific moisture conditions. We conclude that true colour images can be used effectively to monitor phenology and biomass in high Arctic tundra. The simplicity and affordability of the photographic method represents an opportunity to expand observations in tundra ecosystems.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 42
    Publication Date: 2022-05-24
    Description: Pico, the youngest island of the Azores Archipelago (Portugal), is characterized by a central volcano and a 30-km-long fissure zone. Its eruption rate is the highest of the Azores islands, with more than 35 eruptions in the last 2000 years. Here, we estimate the lava-flow hazard for Pico Island by combining the vent opening probability derived from the spatial distribution of eruptive fissures, the classes of expected eruptions inferred from the physical and chemical characteristics of historical eruptions, and the lava-flow paths simulated by the MAGFLOW model. The most likely area to host new eruptions is along a WNW–ESE trend centred on the central volcano, with the highest hazard affecting the two main residential zones of Lajes do Pico and Madalena. Our analysis is the first attempt to assess the lava-flow hazard for Pico Island, and may have important implications for decision-making in territorial management and future land-use planning.
    Description: Published
    Description: 156-161
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: lava flow hazard ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 43
    Publication Date: 2022-06-10
    Description: Patagonia Argentina is a key area for the study of sea level changes in the southern hemisphere, but the availability of reliable sea level markers in this area is still problematic. In fact the storm deposits (beach ridge) commonly used here to reconstruct past sea level oscillations introduce a wide error. Along the Puerto Deseado coast (Santa Cruz), morphometric analyses of 11 features were carried out using traditional measurement tools and a digital software-based method (tested on one selected feature) with the aim to investigate the possibility of their use as sea level markers. By undertaking accurate topographic profiles we identified the relationship between notches and current sea level. In detail, we identified two clusters of notch retreat point elevations, with a very low internal variability. The lower was located a little below the mean high tide level (mHT) and the upper located at least 0.5m above the maximum high tide level (MHT). Field observations of tidal levels and the position of notches suggest that the lower notches are active and the upper are inactive. This study on the abrasive notches attests their quality as sea level markers and opens up the use of fossil abrasive notches as palaeo sea level markers because the error linked to these features is substantially smaller than that introduced by beach ridges commonly used in the study area
    Description: Published
    Description: 1550 – 1558
    Description: 4A. Clima e Oceani
    Description: JCR Journal
    Description: restricted
    Keywords: notch; rocky coast; sea level marker; Patagonia; Argentina ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 44
    Publication Date: 2022-06-14
    Description: Rayleigh wave group velocity dispersion measurements from local and regional earthquakes are used to interpret the lithospheric structure in the Gulf of California region. We compute group velocity maps for Rayleigh waves from 10 to 150 s using earthquakes recorded by broadband stations of the Network of Autonomously Recording Seismographs in Baja California and Mexico mainland, UNM in Mexico, BOR, DPP and GOR in southern California and TUC in Arizona. The study area is gridded in 120 longitude cells by 180 latitude cells, with an equal spacing of 10 × 10 km. Assuming that each gridpoint is laterally homogeneous, for each period the tomographic maps are inverted to produce a 3-D lithospheric shear wave velocity model for the region. Near the Gulf of California rift axis, we found three prominent low shear wave velocity regions, which are associated with mantle upwelling near the Cerro Prieto volcanic field, the Ballenas Transform Fault and the East Pacific Rise. Upwelling of the mantle at lithospheric and asthenospheric depths characterizes most of the Gulf. This more detailed finding is new when compared to previous surface wave studies in the region. A low-velocity zone in northcentral Baja at ∼28oN which extends east–south–eastwards is interpreted as an asthenospheric window. In addition, we also identify a well-defined high-velocity zone in the upper mantle beneath central-western Baja California, which correlates with the previously interpreted location of the stalled Guadalupe and Magdalena microplates. We interpret locations of the fossil slab and slab window in light of the distribution of unique post-subduction volcanic rocks in the Gulf of California and Baja California.We also observe a high-velocity anomaly at 50-km depth extending down to ∼130 km near the southwestern Baja coastline and beneath Baja, which may represent another remnant of the Farallon slab.
    Description: Published
    Description: 1861-1877
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: surface waves ; seismic tomography ; dynamics of lithosphere and mantle ; crustal structure ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 45
    Publication Date: 2022-05-24
    Description: Earthquake source inversions based on space-borne Synthetic Aperture Radar interferometry (InSAR) are used extensively. Typically, however, only the line-of-sight (LoS) surface displacement component is measured, which is mainly sensitive to the vertical and E–W deformations, although well-established methods also exist to estimate the flight-path component, which is highly sensitive to the N–S displacement. With high-resolution sensors, these techniques are particularly appealing, because accuracies in the order of 3 cm can be achieved, while retaining spatial resolutions between 45 m and a few km, depending on the required level of filtering. We discuss the application to COSMO-SkyMed SAR imagery of the Spectral Diversity or Multi Aperture Interferometry technique, presenting the first SAR flight-path displacement field associated with the Mw 6.3, 2009 L’Aquila event (central Apennines). Finally, we observe and characterize a previously unknown misregistration pattern.
    Description: Published
    Description: 28-35
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Crustal Deformation ; Multi Aperture Interferometry MAI ; InSAR ; L'Aquila Earthquake ; Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
    Publication Date: 2022-05-24
    Description: We present an application of the novel SISTEM approach, to obtain the dense 3D ground deformation pattern produced by the April 6, 2009, Mw 6.3 L’Aquila earthquake. This event, characterized by a SW-dipping normal fault with thousands of foreshocks and aftershocks located in the depth range 5–15 km, is the most destructive to have struck the Abruzzo region since the major 1703 seismic sequence. The surface deformation, revealed by the SISTEM through the integration of GPS with interferometric measurements from the ENVISAT and ALOS satellites, shows a deformed area extending towards SE along the Aterno valley, in agreement with seismological and other geodetic observations. We inverted the SISTEM results using an optimization algorithm based on the genetic algorithm, providing an accurate spatial characterization of ground deformation. Our results improve previous kinematic solutions for the Paganica fault and allow identification of additional faults that have contributed to the observed complex ground deformation pattern.
    Description: Published
    Description: 79-85
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: L'Aquila earthquake, SISTEM, GPS ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    Publication Date: 2022-05-24
    Description: This study investigates in detail the deformation events that have affected the sedimentary successions forming the substrate of Mt. Etna volcano (Italy). Based on the geometric reconstruction of a buried sedimentary marker, we have been able to identify and quantify the effects of three different mechanisms of deformation that have affected the area in the last 600 ka. Numerical results from Finite Element Method (FEM) applied to model viscoelastic deformation suggest the occurrence of a crustal doming process originating at the mantle-crust transition (~16 km). We propose that the source of deformation is related to the diapiric uprise of hydrothermal material originating in altered ocean-like crust and its emplacement at a shallower level in the crust. This process has great relevance in the volcanic system and should be considered for the full assessment of its origin and evolution.
    Description: Published
    Description: 338 – 345
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic doming ; viscoelastic modeling ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 48
    Publication Date: 2022-05-24
    Description: Continuous GPS (CGPS) data, collected at Mt. Etna between April 2012 and October 2013, clearly define inflation/deflation processes typically observed before/after an eruption onset. During the inflationary process from May to October 2013, a particular deformation pattern localised in the upper North Eastern sector of the volcano suggests that a magma intrusion had occurred a few km away from the axis of the summit craters, beneath the NE Rift system. This is the first time that this pattern has been recorded by CGPS data at Mt. Etna. We believe that this inflation process might have taken place periodically at Mt. Etna and might be associated with the intrusion of batches of magma that are separate from the main feeding system. We provide a model to explain this unusual behaviour and the eruptive regime of this rift zone, which is characterised by long periods of quiescence followed by often dangerous eruptions in which vents can open at low elevation and thus threaten the villages in this sector of the volcano.
    Description: Published
    Description: 356-363
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Shallow intrusion beneath NE Rift system ; Mt. Etna volcano ; CGPS data ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 49
    Publication Date: 2024-04-05
    Description: Secondary microseisms recorded by seismic stations are generated in the ocean by the interaction of ocean gravity waves.We present here the theory for modelling secondary microseismic noise by normal mode summation.We show that the noise sources can be modelled by vertical forces and how to derive them from a realistic ocean wave model. We then show how to compute bathymetry excitation effect in a realistic earth model by using normal modes and a comparison with Longuet–Higgins approach. The strongest excitation areas in the oceans depends on the bathymetry and period and are different for each seismic mode. Seismic noise is then modelled by normal mode summation considering varying bathymetry. We derive an attenuation model that enables to fit well the vertical component spectra whatever the station location. We show that the fundamental mode of Rayleigh waves is the dominant signal in seismic noise. There is a discrepancy between real and synthetic spectra on the horizontal components that enables to estimate the amount of Love waves for which a different source mechanism is needed. Finally, we investigate noise generated in all the oceans around Africa and show that most of noise recorded in Algeria (TAM station) is generated in the Northern Atlantic and that there is a seasonal variability of the contribution of each ocean and sea.
    Description: Published
    Description: 1732-1745
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Surface waves and free oscillations ; Seismic attenuation ; Theoretical seismology ; Wave propagation ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 50
    Publication Date: 2024-04-05
    Description: Secondary microseismic noise is generated by non-linear interactions between ocean waves at the ocean surface. We present here the theory for computing the site effect of the ocean layer upon body waves generated by noise sources distributed along the ocean surface. By defining the wavefield as the superposition of plane waves, we show that the ocean site effect can be described as the constructive interference of multiply reflected P waves in the ocean that are then converted to either P or SV waves at the ocean–crust interface. We observe that the site effect varies strongly with period and ocean depth, although in a different way for body waves than for Rayleigh waves. We also show that the ocean site effect is stronger for P waves than for S waves. We validate our computation by comparing the theoretical noise body wave sources with the sources inferred from beamforming analysis of the three seismogram components recorded by the Southern California Seismic Network. We use rotated traces for the beamforming analysis, and we show that we clearly detect P waves generated by ocean gravity wave interactions along the track of typhoon Ioke (2006 September). We do not detect the corresponding SV waves, and we demonstrate that this is because their amplitude is too weak.
    Description: Published
    Description: 1096-1106
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Body waves ; Site effects ; Theoretical Seismology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
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  • 51
    Publication Date: 2024-05-09
    Description: The Sulmona plain (central Italy) is an intramontane basin of the Abruzzi Apennines that is known in the literature for its high seismic hazard. We use extensive measurements of ambient noise to map the fundamental frequency and to detect the presence of geological heterogeneities in the basin. We perform noise measurements along two basin-scale orthogonal transects, in conjunction with 2-D array experiments in specific key areas. The key areas are located in different positions with respect to the basin margins: one at the eastern boundary (fault-controlled basin margin) and one in the deepest part of the basin. We also collect independent data by using active seismic experiments (MASW), down-hole and geological surveys to characterize the near-surface geology of the investigated sites. In detail, the H/V noise spectral ratios and 2-D array techniques indicate a fundamental resonance (f0) in the low-frequency range (0.35–0.4 Hz) in the Sulmona Basin. Additionally, our results highlight the important role that is played by the alluvial fans near the edge-sectors of the basin, which are responsible for a velocity inversion in the uppermost layering of the soil profile. The H/V ratios and the dispersion curves of adjacent measurements strongly vary over a few dozens of meters in the alluvial fan area. Furthermore, we perform 1-D numerical simulations that are based on a linear-equivalent approach to estimate the site response in the key areas, using realistic seismic inputs. Finally, we perform a 2-D simulation that is based on the spectral element method to propagate surface waves in a simple model with an uppermost stiff layer, which is responsible for the velocity inversion. The results from the 2-D modelling agree with the experimental curves, showing deamplified H/V curves and typical shapes of dispersion curves of a not normally dispersive site.
    Description: Published
    Description: 418-439
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Fourier analysis, Earthquake ground motions, Site effects ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 52
    Publication Date: 2015-07-01
    Description: Because of their rapid maneuverability, extended operational range, and improved personnel safety, unmanned aerial vehicles (UAVs) with vision-based systems have great potential for monitoring, detecting, and fighting forest fires. Over the last decade, UAV-based forest fire fighting technology has shown increasing promise. This paper presents a systematic overview of current progress in this field. First, a brief review of the development and system architecture of UAV systems for forest fire monitoring, detection, and fighting is provided. Next, technologies related to UAV forest fire monitoring, detection, and fighting are briefly reviewed, including those associated with fire detection, diagnosis, and prognosis, image vibration elimination, and cooperative control of UAVs. The final section outlines existing challenges and potential solutions in the application of UAVs to forest firefighting.
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  • 53
    Publication Date: 2018-09-01
    Description: Net CO2 assimilation (AN) is an important physiological indicator that reflects the photosynthetic capacity. The seasonal and spatial variations of AN play an important role in carbon uptake simulations, especially for trees. To gain a clearer understanding of the state of the branch carbon balance, it is necessary to more carefully evaluate the dynamic variation of AN over different gradients in the crown during the growing season. Gas exchange, leaf temperature (Tleaf), vapor pressure deficit (VPD), leaf mass per area (LMA), and relative depth into crown (RDINC) were measured throughout the growing season of planted Larix olgensis A. Henry trees. A semi-empirical model for predicting multilayered crown AN was established by incorporating Tleaf, VPD, LMA, RDINC, and their combinations into a photosynthetic light response (PLR) curve model using re-parameterization. The model was assessed based on goodness of fit (adjusted coefficient of determination ([Formula: see text]), root mean square error (RMSE), and Akaike’s information criterion (AIC)) and on the validation results (mean error (ME), mean absolute error (MAE), precision estimation (P)) and performed well. The multilayered predicted model of crown AN lays the foundation for calculating the multilayered photosynthetic production within the crown and determining the range of the functional crown for individual trees.
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  • 54
    Publication Date: 2015-07-01
    Description: Boreal peatlands in Canada comprise a substantial store of soil organic carbon (peat), and this peat is vulnerable to extensive burning during periods of extended drying. Increased frequency of extreme weather events in boreal regions is expected with future climate change, and the conditions that would support sustained smouldering peat combustion within peatlands may be more common. Organic soils tend to burn by smouldering combustion, a very slow-moving process in fuels such as those found in peatlands. Thus the most extreme conditions for carbon loss to the atmosphere due to the burning of peat likely occur when widespread propagation of flaming combustion leads to widespread initiation of smouldering. To investigate the potential for large-scale, high-intensity fire spread across forested bogs, we examined the fuel conditions in forested bogs necessary to support active crown fire. We measured surface and canopy fine fuels (those available to contribute to the propagating energy flux of the main flaming front) across a postfire chronosequence of forested boreal bog from central Alberta, Canada. We found that fuel load of fine surface material remained relatively constant across the chronosequence and at levels large enough to support crown fire initiation. Black spruce (Picea mariana (Mill.) B.S.P.) regeneration begins to fill in the crown space with increasing time since disturbance and achieves crown bulk densities similar to black spruce upland forests. We estimated that after about 80 years, the black spruce canopy has developed enough available fuel to support active crown fire on between 10% to 40% of days in a typical fire season in central Alberta, Canada. Broad-scale propagation of high-intensity fire across a peatland when coincident with drought-induced lower moisture in deep peatland layers has the potential to lead to a substantial release of stored terrestrial carbon.
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  • 55
    Publication Date: 2018-09-01
    Description: Understanding patterns of aboveground carbon storage across forest types is increasingly important as managers adapt to threats of global change. We combined field measures of aboveground biomass with lidar to model fine-scale biomass in deciduous forests located in two watersheds; one watershed was underlain by sandstone and the other by shale. We measured tree and shrub biomass across three topographic positions for both watersheds and analyzed biomass using mixed models. The watershed underlain by shale had 60% more aboveground biomass than the sandstone watershed. Although spatial patterns of biomass were different across watersheds, both had higher (between about 40% and 55%) biomass values at the toe-slope position than at the ridge-top position. To model fine-scale spatial patterns of biomass, we tested the effectiveness of leaf-on and leaf-off lidar combined with topographic metrics to develop a spatially explicit random forest model of tree and shrub biomass across both watersheds. Leaf-on variables were more important for modeling shrub biomass, while leaf-off variables were more effective at modeling tree biomass. Our model of tree and shrub biomass reflects the distribution of biomass across both watersheds at a fine scale and highlights the potential of abiotic factors such as topography and bedrock to affect carbon storage.
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  • 56
    Publication Date: 2016-11-01
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  • 57
    Publication Date: 2015-06-01
    Description: Resource development can have significant consequences for the distribution of vegetation cover and for species persistence. Modelling changes to anthropogenic disturbance regimes over time can provide profound insights into the mechanisms that drive land cover change. We analyzed the spatial patterns of anthropogenic disturbance before and after a period of significant oil and gas extraction in two boreal forest subregions in Alberta, Canada. A spatially explicit model was used to map levels of anthropogenic forest crown mortality across 700 000 ha of managed forest over a 60-year period. The anthropogenic disturbance regime varied both spatially and temporally and was outside the historical range of variability characterized by regional fire regimes. Levels of live forest crown within anthropogenic disturbances declined and edge density increased following oil and gas development, whereas patch size varied regionally. In some places, anthropogenic disturbance generated profoundly novel landscapes with spatial patterns that had no historical analogue in the boreal system. The results illustrate that a shift in one sector of the economy can have dramatic outcomes on landscape structure. The results also suggest that any efforts to better align cumulative anthropogenic disturbance patterns with the historic baseline will almost certainly require a concerted and collaborative effort from all of the major stakeholders.
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  • 58
    Publication Date: 2015-08-01
    Description: In many recent studies, the value of forest inventory information in harvest scheduling has been examined. In a previous paper, we demonstrated that making measurement decisions for stands for which the harvest decision is uncertain simultaneously with the harvest decisions may be highly profitable. In that study, the quality of additional measurements was not a decision variable, and the only options were between making no measurements or measuring perfect information. In this study, we introduce data quality into the decision problem, i.e., the decisionmaker can select between making imperfect or perfect measurements. The imperfect information is obtained with a specific scenario tree formulation. Our decision problem includes three types of decisions: harvest decisions, measurement decisions, and decisions about measurement quality. In addition, the timing of the harvests and measurements must be decided. These decisions are evaluated based on two objectives: discounted aggregate income for the planning periods and the end value of the forest at the end of the planning horizon. Solving the bi-objective optimization problem formed using the ε-constraint method showed that imperfect information was mostly sufficient for the harvest timing decisions during the planning horizon but perfect information was required to meet the end-value constraint. The relative importance of the two objectives affects the measurements indirectly by increasing or decreasing the number of certain decisions (i.e., situations in which the optimal decision is identical in all scenarios).
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  • 59
    Publication Date: 2018-04-01
    Description: The contribution of forest biomass to Canada’s energy production is small but growing. As the forest bioenergy industry in Canada expands, there is growing interest in more sustainably managing the wood ash that is generated as a by-product. Despite being rich in nutrients, wood ash is usually landfilled in Canada. Soil applications of ash in Canadian forests could be used to mimic some of the effects of wildfire, to replace nutrients removed during harvesting, to counteract the negative effects of acid deposition, and to improve tree growth. At present, the provincial and territorial processes for obtaining regulatory approval to use wood ash as a forest soil amendment can be challenging to navigate. Furthermore, the costs for obtaining approval and transporting and applying wood ash to the soil can render landfilling a more cost-effective method of ash management. To ensure that wood ash applications in Canadian forests are conducted safely, effectively, and efficiently, experience from European countries could provide a useful starting point for developing best practices. The results of Canadian research trials will assist policy makers and forest managers in refining management guidelines that encourage soil applications of wood ash as a forest management tool while protecting the ecology, water quality, biodiversity, and productivity of Canadian forests.
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  • 60
    Publication Date: 2017-01-01
    Description: Genetic variation and population structure in biomass yield and coppice growth traits were assessed in seven native North American willow species (Salix amygdaloides (AMY), Salix bebbiana (BEB), Salix discolor (DIS), Salix eriocephala (ERI), Salix humilis (HUM), Salix interior (INT), and Salix nigra (NIG)) established together in common-garden field tests on two sites. Differences in biomass yield, coppice stem number, and average single-stem mass were significant at the site, species, population, and genotype (clonal) levels. There were also species × site interactions. Analyses of variance components for these traits showed that only 3%–5% of the total variation in these traits was due to site differences, whereas genetic variation at the species, population, and genotype levels accounted for approximately 10%–39%, 5%–13%, and 12%–23%, respectively. Populations were a significant source of variation in some willow species (e.g., AMY, DIS, ERI, and INT) but not in other species. Tree willows were less prolific in stem sprout production than shrub willows, and ERI coppices produced by far the highest number of stem sprouts per coppice. This multispecies investigation demonstrated strong species and clonal differences, but variation among populations within a species, although significant, was relatively small, indicating that major growth and yield gains can be made through proper species selection and clonal selection within local populations.
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  • 61
    Publication Date: 2018-01-01
    Description: Bud burst is one of the most observable phenological stages in tree species, and its responses to environmental factors are found to be species-specific. Nevertheless, for dioecious plants, whether the bud burst responses are sex specific remains an open question, as do the underlying physiological mechanisms. Here, we investigated the effect of elevated temperature (+2 °C) and drought (30% field capacity) during December–March on bud development, gas exchange, water and nitrogen status, and carbohydrate metabolism in female and male Populus cathayana to understand how nongrowing season warming and drought modifies physiological and phenological traits. Our results showed that at ambient temperature, males experienced earlier bud burst than females. Winter warming significantly delayed bud burst and even synchronized it for both sexes because of the greater responsiveness of males. Although drought exerted little effect on the timing of bud burst, it significantly reduced bud fresh mass and limited bud growth by decreasing gas exchange capacity and nonstructural carbohydrate (NSC) accumulation; moreover, females were more affected by drought stress. The significant sex × watering × temperature interactions for δ13C and NSC indicate that sexual dimorphism in these condition-specific traits would increase along the environmental gradients, implying contrasting life history strategies in different ecological scenarios. The convergence in the time for bud burst caused by elevated temperature might exaggerate the competition among males, thus influencing the sex ratio, structure, and functioning of P. cathayana populations.
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  • 62
    Publication Date: 2016-09-01
    Description: This study considered airborne laser scanning (ALS) based aboveground biomass (AGB) prediction in mountain forests. The study area consisted of a long transect from southern Norway to northern parts of the country with wide ranges of elevation along a long latitudinal gradient (58°N–69°N). This transect was covered by ALS data and field data from 238 plots. AGB was modeled using different types of predictor variables, namely ALS metrics, variables related to growing conditions (elevation, latitude, and climatic variables), and tree species information. Modelling of AGB in the long transect covering diverse mountainous forest conditions was challenging: the RMSE values were rather large (37%–70%). The effects of growing conditions on model predictions were minor. However, species information was essential to improve accuracy. The analysis revealed that when doing inventories of spruce-dominated areas, all plots should be pooled together when the models are developed, whereas if pine or deciduous species dominate the area in question, separate dominant species-wise models should be constructed.
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  • 63
    Publication Date: 2015-08-01
    Description: The impact of root water uptake on duff (both fibric and humic horizons) moisture was investigated at deciduous, mixedwood, and conifer stands in Ontario, Canada. Roots were actively excluded from the duff layer using geotextiles inserted at the duff–mineral soil interface and along the plot edges; liquid and vapour water flow was otherwise not affected by the geotextiles. Root exclusion caused little difference in duff moisture content prior to early June, after which the root exclusion plots remained at 15%–20% volumetric water content, whereas root-intact plots declined to as low as 5% volumetric water content during rain-free periods. Only in the root-intact plots did the duff water content reach sufficiently low levels that duff evaporation was limited by low water content. The net effect of root exclusion was to reduce the cumulative growing season water loss in the duff by 19%–31%, depending on the stand type. Root exclusion also decreased the number of days with a high probability of duff smouldering from as many as 72 days·year−1 to as few as 0 days·year−1. This root exclusion experiment provides a model for short-term duff moisture transitions under thinned forests such as those forests under community wildfire protection.
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  • 64
    Publication Date: 2018-05-01
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  • 65
    Publication Date: 2016-03-01
    Description: As part of the development of the 2011 National Land Cover Database (NLCD) tree canopy cover layer, a pilot project was launched to test the use of high-resolution photography coupled with extensive ancillary data to map the distribution of tree canopy cover over four study regions in the conterminous US. Two stochastic modeling techniques, random forests (RF) and stochastic gradient boosting (SGB), are compared. The objectives of this study were first to explore the sensitivity of RF and SGB to choices in tuning parameters and, second, to compare the performance of the two final models by assessing the importance of, and interaction between, predictor variables, the global accuracy metrics derived from an independent test set, as well as the visual quality of the resultant maps of tree canopy cover. The predictive accuracy of RF and SGB was remarkably similar on all four of our pilot regions. In all four study regions, the independent test set mean squared error (MSE) was identical to three decimal places, with the largest difference in Kansas where RF gave an MSE of 0.0113 and SGB gave an MSE of 0.0117. With correlated predictor variables, SGB had a tendency to concentrate variable importance in fewer variables, whereas RF tended to spread importance among more variables. RF is simpler to implement than SGB, as RF has fewer parameters needing tuning and also was less sensitive to these parameters. As stochastic techniques, both RF and SGB introduce a new component of uncertainty: repeated model runs will potentially result in different final predictions. We demonstrate how RF allows the production of a spatially explicit map of this stochastic uncertainty of the final model.
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  • 66
    Publication Date: 2015-03-01
    Description: Trees form the terrestrial interface with the atmosphere in forested regions. The electrical properties of trees may influence their response to atmospheric conditions and potentially lethal phenomena (e.g., lightning). We review the literature describing electrical properties of trees and provide a tabular summary of the methods and goals of each study. We hypothesized that electrical resistivity varies consistently among species and between growth forms. We surveyed resistivity of eight tree and three vine species in Michigan and Kentucky, and we quantified resistivity over a moisture gradient for wood blocks of four tree species. Resistivity varied predictably with stem diameter and differed among species and growth forms. Specifically, resistivity of trees was approximately 200% higher than resistivity of vines, and resistivity of conifers was 135% higher than that of hardwoods. The regional comparison showed no difference in resistivity of red maple (Acer rubrum L.) and sugar maple (Acer saccharum Marsh.) between Michigan and Kentucky. These results, in combination with interspecific differences observed among wood blocks, suggest that there is a phylogenetic basis for variation in resistivity that reflects differences in anatomy and physiology. Our review and empirical survey provide a framework for studying the ecological effects of lightning in the context of the electrical properties of trees.
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  • 67
    Publication Date: 2018-12-01
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  • 68
    Publication Date: 2015-11-01
    Description: The influence of forest ecology and strategic planning has increased in importance to support the management of mixed-species forests to enhance biodiversity. However, little is known about competitive and facilitative interactions between trees and species in mixed fir–beech–spruce forests, mostly because of a lack of long-term experimental research. In the 1960s, long-term sample plots were established in the Western Carpathians to develop region-specific yield models. Trees in the plots were measured at 5- to 16-year intervals from 1967(69). In 2010, the positions of standing trees in all plots were identified spatially. Stump positions were also identified to record the coordinates of trees that had been removed or had died. The objectives of this study were to evaluate the applicability of widely used competition indices for mature fir–beech–spruce mixed forests and to test whether the tree competition zone changes among species and forest stands of different stocking densities. Results showed that the best competition index was based on the comparison of the basal area of competitors and the subject tree in the radius, which was defined as a function of stand density and species. In addition, beech was found to be a strong self-competitor, which was not the case for silver fir (Abies alba Mill.). Results suggest that simpler competition indices are better suited for such diverse forests, as more complex indices do not describe the competition interactions sufficiently well.
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  • 69
    Publication Date: 2018-09-01
    Description: Wildfires, insect outbreaks, and windstorms are increasingly common forest disturbances. Post-disturbance management often involves salvage logging, i.e., the felling and removal of the affected trees; however, this practice may represent an additional disturbance with effects on ecosystem processes and services. We developed a systematic map to provide an overview of the primary studies on this topic and created a database with information on the characteristics of the retrieved publications, including information on stands, disturbance, intervention, measured outcomes, and study design. Of 4341 retrieved publications, 90 were retained in the systematic map. These publications represented 49 studies, predominantly from North America and Europe. Salvage logging after wildfire was addressed more frequently than after insect outbreaks or windstorms. Most studies addressed logging after a single disturbance event, and replication of salvaged stands rarely exceeded 10. The most frequent response variables were tree regeneration, ground cover, and deadwood characteristics. This document aims to help managers find the most relevant primary studies on the ecological effects of salvage logging. It also aims to identify and discuss clusters and gaps in the body of evidence, relevant for scientists who aim to synthesize previous work or identify questions for future studies.
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  • 70
    Publication Date: 2015-06-01
    Description: The parsimonious taper function proposed by Riemer et al. (1995. Allg. Forst.- Jagdztg. 166(7): 144–147) was fitted for radiata pine (Pinus radiata D. Don) stems in Spain by using a nonlinear mixed modelling approach. Eight candidate models (all possible expansion combinations of the three fixed parameters with random effects) were assessed, and the mixed model with three random effects performed the best according to the goodness-of-fit statistics. An evaluation data set was used to assess the performance of these models in predicting stem diameter along the bole, as well as total stem volume. Four prediction approaches were compared: one subject (tree) specific (SS) and three population specific (ordinary least squares (OLS), mean (M), and population averaged (PA)). The SS responses for a tree were estimated from a prior stem diameter measurement available for that tree, whereas OLS, M, and PA were obtained from the fixed-effects model, from the fixed parameters of mixed-effects models, and by computing mean predictions from the mixed-effects models over the distribution of random effects, respectively. Prediction errors were greater for the M and PA responses than for the OLS response, and therefore, from the prediction point of view, the use of the mixed-effects models is not recommended when an additional stem diameter measurement is not available. The mixed model with three random effects was also selected as the best model for SS estimations. Measurement of an additional stem diameter at a relative tree height of approximately 0.5 provided the best calibrations for stem diameters along the bole and total stem volume predictions. The SS approach increased the flexibility and efficiency of the selected mixed-effects model for localized predictions and thus improved the overall predictive capacity of the base model.
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  • 71
    Publication Date: 2016-05-01
    Description: To better understand climatic origins of annual tree-growth anomalies in boreal forests, we analysed 895 black spruce (Picea mariana (Mill.) B.S.P.) tree-growth series from 46 xeric sites situated along three latitudinal transects in Eastern Canada. We identified interannual (based on comparison with previous year growth) and multidecadal (based on the entire tree-ring width distribution) growth anomalies between 1901 and 2001 at site and transect levels. Growth anomalies occurred mainly at site level and seldom at larger spatial scales. Both positive interannual and multidecadal growth anomalies were strongly associated with below-average temperatures and above-average precipitation during the previous growing season (Junet–1 – Augustt–1). The climatic signature of negative interannual and multidecadal growth anomalies was more complex and mainly associated with current-year climatic anomalies. Between the early and late 20th century, only negative multidecadal anomalies became more frequent. Our results highlight the role of previous growing season climate in controlling tree growth processes and suggest a positive association between climate warming and increases in the frequency of negative multidecadal growth anomalies. Projected climate change may further favour the occurrence of tree-growth anomalies and enhance the role of site conditions as modifiers of tree response to regional climate change.
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  • 72
    Publication Date: 2019-03-01
    Description: A two-year field study was carried out to determine whether inoculating white spruce, Picea glauca (Moench) Voss, with a native endophytic fungus, Phialocephala scopiformis DAOM 229536 Kowalski & Kehr (Helotiales, Ascomycota), decreased the performance of eastern spruce budworm, Choristoneura fumiferana Clemens, developing on these trees. Second instars were reared at three densities in the mid crown and at one density in the lower, mid, and upper crown. Larval survival (i.e., survival of larvae to pupation) was lower on endophyte-inoculated trees than on control trees in the mid crown and especially the upper crown but was similar in the lower crown, resulting in a significant interaction between endophyte and crown level. A similar but marginally insignificant interaction was observed for overall survival up to adult emergence (i.e., total survival). Larval survival and total survival were approximately 22% and 19% lower, respectively, when developing in the upper crown of endophyte-inoculated trees than in control trees. Larval survival remained relatively constant, with increased density on control trees but decreased with density on endophyte-inoculated trees, resulting in a significant interaction between endophyte and larval density. Sex ratios of emerged adults and wing lengths of emerged females were not influenced by the endophyte. Our results suggest that endophytic fungi could be useful additions to integrated pest management programs.
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  • 73
    Publication Date: 2019-05-01
    Description: Quantitative genetic variation of fiber-dimension traits and their relationship with diameter at breast height (DBH) and solid-wood traits (i.e., density and modulus of elasticity (MOE)) was investigated in lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.). A total of 823 increment cores were sampled from 207 half-sib families at two independent progeny trials, aged 34–35 years, located in northern Sweden. High-resolution pith-to-bark profiles were obtained for radial fiber width (RFW), tangential fiber width (TFW), fiber wall thickness (FWT), and fiber coarseness (FC) using SilviScan. Heritabilities ranged from 0.29 to 0.74, and inheritance increased with cambial maturity. Estimated age–age genetic correlations indicate that early selection between ages 5 and 8 years is highly efficient. Our results indicate that selection for a 1% increase in DBH or MOE incurs a negligible effect on fiber-dimension traits and maximum genetic gains are reached when DBH and MOE are considered jointly. Moreover, simultaneous improvement of growth and stiffness is achievable when a selection index with 7 to 10 economical weights for MOE relative to 1 for DBH is incorporated. However, the unfavorable relationship between solid-wood traits and pulp and paper related traits suggests that breeding strategies must be implemented to improve wood quality of lodgepole pine for multiple uses.
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  • 74
    Publication Date: 2019-05-01
    Description: Lack of generalized equations has prevailed in Brazil, because it is assumed that localized or climate-specific equations are needed. This study aimed to develop generalized stem taper and volume equations applicable to 11 eucalyptus clones and evaluate if climate variation impacts the accuracy of the estimates. A total of 693 trees evenly distributed across 11 clones at 21 sites were used for model fittings and predictive validation. The penalized mixed spline (PMS) approach was developed for predicting stem taper and volume along the stem profile. The Schumacher and Hall (1933) equation was used to predict total tree volume, while volume ratio equations were applied to predict merchantable volume. For every fitted equation, an annual climatic variable was included to assess the improvement in model performance. The overall results highlighted that climatic variation does not need to be accounted for in stem taper and volume modeling. All of the equations displayed desirable accuracy, but the generalized PMS equation may be preferred when the forestry enterprise looks to furnish a range of multiple forest products. The generalized total tree volume equation, combined with the ratio equations, is highly recommended when the forestry enterprise produces a single product.
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  • 75
    Publication Date: 2016-03-01
    Description: Wood ash may be an effective soil amendment in North America to restore acidified and low-nutrient forest soils, but little research exists beyond its effects on soil and plants. Eastern Red-backed Salamander (Plethodon cinereus (Green, 1818)) abundance was assessed in a northern hardwood forest 1 year following an ash-addition field trial. Plots were established with fly ash and bottom ash treatments of 0, 1, 4, and 8 Mg·ha−1 (n = 4), and cover boards were positioned both with and without ash beneath. One year following ash additions, salamander abundance had increased under boards with fly ash beneath, and bottom ash had no effect. Soil pH and electrical conductivity increased under cover boards with ash beneath them and for uncovered soil, and the effects were strongest under cover boards with ash beneath. The effects of ash were generally stronger at higher dosages, and fly ash was stronger than bottom ash. The moisture holding capacity of fly ash was 60% higher than the soil and was 63% lower than the soil for bottom ash, but they had little effect on moisture of the forest floor. These results suggest that ash altered salamander abundance via soil pH and moisture and would not inhibit salamander movement over the forest floor.
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  • 76
    Publication Date: 2016-05-01
    Description: Forest health deteriorated in eastern North America as a result of depletion of available soil base cations by elevated inputs of acid deposition. We experimentally restored available calcium (Ca) to soils of a forested watershed at Hubbard Brook, New Hampshire, and measured the response of fine root biomass 14 years after treatment. In this northern hardwood forest, fine root (
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  • 77
    Publication Date: 2019-03-01
    Description: Vegetation–soil systems differentially influence the ecosystem processes related to the carbon cycle, particularly when one tree species is dominant over wide geographic regions that are undergoing climate change. The objective of this study was to quantify the stocks of ecosystem carbon in three vegetation–soil systems along a highland elevational gradient in central Mexico. The vegetation–soil systems, from lower to higher elevation, were dominated by Alnus jorullensis Kunth, Abies religiosa (Kunth) Schltdl. & Cham., and Pinus hartwegii Lindl., respectively. Above- and below-ground tree biomass was determined in each system, along with the litter, coarse woody material, roots, and litterfall. The A. religiosa system had the greatest stock of aboveground biomass carbon (216 ± 31 Mg C·ha−1). The A. jorullensis system had the greatest production of litterfall (3.1 ± 0.08 Mg·ha−1·year−1); however, the carbon content of this litter layer (1.2 ± 0.32 Mg C·ha−1) was lower than that of P. hartwegii (10.1 ± 0.28 Mg C·ha−1). Thus, the litter layer in the A. jorullensis system had markedly the shortest residence time (8 years), suggesting high rates of litter decomposition. The soil carbon stock (at soil depth of 1 m) was greater in A. jorullensis (189 Mg C·ha−1) and P. hartwegii (137 Mg C·ha−1) than in A. religiosa (68 Mg C·ha−1). The A. religiosa and A. jorullensis systems had the highest and lowest total ecosystem C content (301 and 228 Mg C·ha−1, respectively). Upward migration of the A. religiosa system in response to global climate change, however, could cause losses by 2030 of 187 Mg C·ha−1 associated with aboveground biomass.
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  • 78
    Publication Date: 2018-05-01
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  • 79
    Publication Date: 2017-08-01
    Description: Conifer winter damage results primarily from loss of cold hardiness during unseasonably warm days in late winter and early spring, and such damage may increase in frequency and severity under a warming climate. In this study, the dehardening dynamics of lodgepole pine (Pinus contorta Dougl. ex. Loud), jack pine (Pinus banksiana Lamb.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) B.S.P.) were examined in relation to thermal accumulation during artificial dehardening in winter (December) and spring (March) using relative electrolyte leakage and visual assessment of pine needles and spruce shoots. Results indicated that all four species dehardened at a similar rate and to a similar extent, despite considerably different thermal accumulation requirements. Spring dehardening was comparatively faster, with black spruce slightly hardier than the other conifers at the late stage of spring dehardening. The difference, however, was relatively small and did not afford black spruce significant protection during seedling freezing tests prior to budbreak in late March and early May. The dehardening curves and models developed in this study may serve as a tool to predict cold hardiness by temperature and to understand the potential risks of conifer cold injury during warming–freezing events prior to budbreak.
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  • 80
    Publication Date: 2018-06-01
    Description: Model-based inference is an alternative to probability-based inference for small areas or remote areas for which probability sampling is difficult. Model-based mean square error estimators incorporate three components: prediction covariance, residual variance, and residual covariance. The latter two components are often considered negligible, particularly for large areas, but no thresholds that justify ignoring them have been reported. The objectives of the study were threefold: (i) to compare analytical and bootstrap estimators of model parameter covariances as the primary factors affecting prediction covariance; (ii) to estimate the contribution of residual variance to overall variance; and (iii) to estimate thresholds for residual spatial correlation that justify ignoring this component. Five datasets were used, three from Europe, one from Africa, and one from North America. The dependent variable was either forest volume or biomass and the independent variables were either Landsat satellite image bands or airborne laser scanning metrics. Three conclusions were noteworthy: (i) analytical estimators of the model parameter covariances tended to be biased; (ii) the effects of residual variance were mostly negligible; and (iii) the effects of spatial correlation on residual covariance vary by multiple factors but decrease with increasing study area size. For study areas greater than 75 km2 in size, residual covariance could generally be ignored.
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  • 81
    Publication Date: 2017-05-01
    Description: The ability to rapidly estimate wind speed beneath a forest canopy or near the ground surface in any vegetation is critical to practical wildland fire behavior models. The common metric of this wind speed is the “mid-flame” wind speed, UMF. However, the existing approach for estimating UMF has some significant shortcomings. These include the assumptions that both the within-canopy wind speed and the canopy structure are uniform with depth (z) throughout the canopy and that the canopy roughness length (z0) and displacement height (d) are the same regardless of canopy structure and foliage density. The purpose of this study is to develop and assess a model of canopy wind and Reynolds stress that eliminates these shortcomings and thereby provide a more physically realistic method for calculating UMF. The present model can be used for canopies of arbitrary plant surface distribution and leaf area, and the single function that describes the within-canopy wind speed is shown to reproduce observed canopy wind speed profiles across a wide variety of canopies. An equally simple analytical expression for the within-canopy Reynolds stress, [Formula: see text], also provides a reasonable description of the observed vertical profiles of Reynolds stress. In turn, [Formula: see text] is used to calculate z0 and d. Tests of operational performance are also discussed.
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  • 82
    Publication Date: 2019-01-01
    Description: Wildland fire dynamics are a complex three-dimensional turbulent process. Cellular automata (CA) is an efficient tool to predict fire dynamics, but the main parameters of the method are challenging to estimate. To overcome this challenge, we compute statistical distributions of the key parameters of a CA model using infrared images from controlled burns. Moreover, we apply this analysis to different spatial scales and compare the experimental results with a simple statistical model. By performing this analysis and making this comparison, several capabilities and limitations of CA are revealed.
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  • 83
    Publication Date: 2019-02-01
    Description: It has recently become clear that the regeneration density of serotinous species within a burned area declines with local fire intensity. It is assumed that this occurs because variation in local fire intensity leads to variation in incident heat fluxes and, ultimately, seed necrosis. We argue here that this same relationship between incident heat flux and seed necrosis is important at the scale of individual plant crowns. Using Picea mariana (Mill.) B.S.P. (black spruce), we show that postfire seed viability increases with crown height, depth into the crown, and angle from wind direction (with the windward side enjoying greater viability). All three effects are what one would expect given the physics of buoyant plumes, interactions of moving fire lines with wake flow around cylinders, and heat transfer in porous bodies such as a tree crown. We conclude by discussing the broader consequences of cone cluster size and global change on regeneration in serotinous species.
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  • 84
    Publication Date: 2019-02-01
    Description: Forest attributes such as volume or basal area are concentrated at tree locations and are absent elsewhere. It is, therefore, more meaningful to consider the amount of forest attributes at a prefixed spatial grain, within regular plots of prefixed size centered at the points of the study area. In this way, the diversity of attributes within plots also can be considered and quantified by suitable indexes, giving rise to a diversity surface defined on the continuum of points constituting the area. We analyze the estimation of diversity surfaces when a sample of plots is selected by a probabilistic sampling scheme and diversity within nonsampled plots is estimated using an inverse distance weighting interpolator. We discuss the design-based asymptotic properties of the resulting maps when the survey area remains fixed and the number of sampled points increases. Because diversity surfaces share suitable mathematical properties, if the schemes adopted to select sample points ensure an even coverage of the study areas avoiding large portions of non-sampled zones, it can be proven that the estimated maps approach the true maps.
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  • 85
    Publication Date: 2015-10-01
    Description: Lightning strikes millions of trees worldwide each year, yet structured lightning damage surveys are relatively rare. Estimates drawn from the literature suggest that lightning directly or indirectly kills up to 4% of large canopy trees in a stand annually. Lightning is a major cause of death for pines in southeastern US forests and for large cacti in some deserts, but its landscape-level effects exclusive of fire at higher latitudes are poorly known. We quantified damage to trees from lightning and other sources in hemlock–hardwood forests of the Huron Mountain Region of Michigan, USA. This region receives ca. 100 cloud-to-ground lightning flashes per year, with most occurring in May to August. We recorded abiotic and biotic damage on 309 trees distributed among nine transects, each 〉2 km long. None of the transect trees had lightning scars, and we observed only 14 clear cases of lightning damage among thousands of trees examined during associated meander surveys (each ca. 0.5 ha). This damage was more commonly associated with emergent stature (50% of struck trees) and higher rates of biotic damage (50%) than we observed in the 309 transect trees (22% emergent status and 16% incidence of biotic damage). Nearly all (93%) of the lightning damaged trees were conifers, suggesting that either susceptibility to, or response to, lightning strikes has a phylogenetic basis. These preliminary results provide a foundation for comparative studies in other forests. Accurate quantification of lightning-induced tree mortality will improve forest turnover models and facilitate predictions of future forest structure under conditions of increased lightning frequency.
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  • 86
    Publication Date: 2017-08-01
    Description: Canada’s National Forest Carbon Monitoring Accounting and Reporting System (NFCMARS) quantifies the carbon (C) dynamics and greenhouse gas (GHG) emissions and removals of Canada’s managed forest to fulfill reporting obligations under international climate conventions. Countries are also requested to assess the uncertainty associated with these estimates, which we report here. We used Monte Carlo simulation to quantify uncertainty of carbon stock and flux estimates from the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3), the core ecosystem model of the NFCMARS. We evaluated the impacts of model algorithms, parameters, and the input data used to describe forest characteristics and disturbance rates. Under our assumptions, 95% confidence interval widths averaged 16.2 Pg C (+8.3 and –7.9 Pg C, or ±15%) for total ecosystem C stock and 32.2 Tg C·year−1 (+16.6 and –15.6 Tg C·year−1) for net biome production relative to an overall simulation median of –0.8 Tg C·year−1 from 1990 to 2014. The largest sources of uncertainty were related to factors determining biomass increment and the parameters used to model soil and dead organic matter C dynamics. Opportunities to reduce uncertainty and associated research challenges were identified.
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  • 87
    Publication Date: 2015-05-01
    Description: Constraints of the physical environment affect forest growth and forest operations. At a local scale, these constraints are generally considered during forest operations. At regional or continental scales, they are often integrated to larger assessments of the potential for a given land unit to be managed. In this study, we propose an approach to analyze the integration of physical-environment constraints in forest management activities at the regional scale (482 000 km2). The land features that pose constraints to forest management (i.e., hydromorphic organic deposits, dead-ice moraines, washed till, glacial block fields, talus, and active aeolian deposits, slopes 〉 40%) were evaluated within 1114 land districts. To distinguish land districts that can be suitably managed from those where constraints are too important for sustainable timber production, we carried out a sensitivity analysis of physical constraints for the 1114 land districts. After analysis of two portions of the study area under management, a land district was considered suitable for management when more than 20% of its land area consists of features imposing few constraints or, for mountain-type relief districts, when more than 40% of the land area consists of features imposing few constraints. These cutoff values were defined by expert opinion, based on sensitivity analyses performed on the entire study area, on analyses of two different sectors with different types of constraints and on a strong understanding of the study area. Our results show that land districts where the physical environment posed significant constraints covered 7.5% of the study area (36 000 km2). This study shows that doing an a priori classification of land units based on permanent environmental features could facilitate the identification of areas that are not suitable for forest management activities.
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  • 88
    Publication Date: 2016-11-01
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  • 89
    Publication Date: 2015-10-01
    Description: Over the period 1883–2013, recruitment of subalpine limber pine (Pinus flexilis E. James) and Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) above the upper tree line, below the lower tree line, and across middle-elevation forest borders occurred at localized sites across four mountain ranges in the western Great Basin. A synchronous pulse at all ecotones occurred between 1963 and 2000 (limber pine) and between 1955 and 1978 (bristlecone pine) when pines expanded 225 m beyond forest borders. Little recruitment occurred before this interval or in the 21st century. No obvious environmental factors distinguished recruitment locations from nonrecruitment locations. Where their ranges overlap, limber pine has leapfrogged above bristlecone pine by 300 m. Limber pine tree-ring chronologies, developed to compare radial-growth responses with recruitment, showed dominant pulses of increased growth during the same interval as recruitment. Significant climate correlations of growth and recruitment indicated lead and lag effects as much as 6 years and complex relationships with climate variables, corroborating the importance of cumulative climate effects relative to any single year. Water relations were the most important drivers of growth and recruitment and interacted with growing-season minimum and maximum temperatures. These results underscore the importance of studying ecotones at all margins when evaluating conifer response to climate change.
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  • 90
    Publication Date: 2016-07-01
    Description: Long-term forest inventories provide a unique opportunity to quantify changes in forest structure and evaluate how changes compare with current stand development models. An examination of a 70 year record at the Bartlett Experimental Forest, New Hampshire, indicated that although species abundances have primarily changed as expected under natural succession, some unexpected results were also detected. This included a significant decline in sugar maple (Acer saccharum Marsh.) abundance driven by reduced regeneration and increases in red spruce (Picea rubens Sarg.) at the expense of sympatric balsam fir (Abies balsamea (L.) Mill.) and hardwoods at upper elevations. In contrast with accepted stand development models, biomass continues to accrue on these mid- to late-successional forests. Importantly, biomass accumulated at even greater rates in recent decades compared with historical norms. These results support evidence that the anthropogenic influences of a changing climate and the legacy of acid deposition may be altering stand dynamics in northeastern forests.
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  • 91
    Publication Date: 2015-12-01
    Description: Most hypotheses about controls over high-altitude forests, including treeline, the elevation for upright woody plants, or timberline, the upper elevation for aggregated forest, suggest that low temperature drives forest dynamics, either through effects on cell division and tree growth or indirectly through frost damage or nutrient availability. However, abiotic factors other than temperature, including water availability, may serve as other important controls at high elevations, particularly for seedlings. To test the hypothesis that the timing and amount of precipitation exerts a strong control over the high-elevation forest boundary on the Wasatch Plateau in central Utah, USA, we conducted a field experiment that manipulated water availability and monitored photosynthesis, growth, and survivorship in Picea engelmannii Parry ex Engelm. seedlings. Survivorship increased from the driest to the wettest conditions, whereas the timing of precipitation did not explain differences in survival. However, we found that large, infrequent rain events increased maximum photosynthetic flux density compared with small, frequent rain events. Our results highlight the potential role of growing season water availability in limiting timberline expansion below the low-temperature thermal limits of P. engelmannii. As a consequence, the infilling of trees below the treeline in this region in response to climate change is likely to be episodic and driven by multiyear periods of high water availability and frequency that overcome drought limitations.
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  • 92
    Publication Date: 2019-02-01
    Description: Ground-based mechanized forestry requires the traversal of terrain by heavy machines. The routes that they take are often called “machine trails” and are created by removing trees from the trail and placing the logs outside it. Designing an optimal machine trail network is a complex locational problem that requires understanding how forestry machines can operate on the terrain, as well as the trade-offs between various economic and ecological aspects. Machine trail designs are currently created manually based on intuitive decisions about the importance, correlations, and effects of many potentially conflicting aspects. Badly designed machine trail networks could result in costly operations and adverse environmental impacts. Therefore, this study was conducted to develop a holistic optimization framework for machine trail network design. Key economic and ecological objectives involved in designing machine trail networks for mechanized cut-to-length operations are presented, along with strategies for simultaneously addressing multiple objectives while accounting for the physical capabilities of forestry machines, the impact of slope, and the operating costs. Ways of quantitatively formulating and combining these different aspects are demonstrated, together with examples showing how the optimal network design changes in response to various inputs.
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  • 93
    Publication Date: 2016-11-01
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  • 94
    Publication Date: 2016-11-01
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  • 95
    Publication Date: 2015-03-01
    Description: European beech (Fagus sylvatica L.) is an economically and ecologically important forest tree species in Europe. Expected future temperature increases due to global climate change may significantly affect growth of beech trees and consequently influence carbon cycling in beech forests. We tested the hypothesis that soil temperature influences the growth of both belowground and aboveground parts of beech seedlings. One-year-old seedlings were transferred into rhizotrons and subjected to two different soil temperatures for 2 years while the soil moisture level was kept constant. The main effect of the soil temperature was a changed biomass of the woody part of the seedlings. Soil temperature significantly influenced the biomass of shoots and roots and diameter of the stem, which were the highest for the seedlings grown in conditions of soil temperatures maintained in the range of summer soil temperatures from the site of origin of the seedlings. Increased soil temperature also resulted in increased specific root length and specific root tip density. Root-to-shoot ratio and leaf parameters (leaf mass, number of leaves, and specific leaf area), except for leaf area ratio, were not influenced by soil temperature.
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  • 96
    Publication Date: 2017-01-01
    Description: Understanding how climate affects tree growth is essential for assessing climate change impacts on forests but can be confounded by effects of competition, which strongly influences tree responses to climate. We characterized the joint influences of tree size, competition, and climate on diameter growth using hierarchical Bayesian methods applied to permanent sample plot data from the montane forests of Mount Rainier National Park, Washington State, USA, which are mostly comprised of Abies amabilis Douglas ex Forbes, Tsuga heterophylla (Raf.) Sarg., Pseudotsuga menziesii (Mirb.) Franco, and Thuja plicata Donn ex D. Don. Individual growth was sensitive to climate under low but not high competition, likely because tree ability to increase growth under more favorable climates (generally greater energy availability) was constrained by competition, with important variation among species. Thus, climate change will likely increase individual growth most in uncrowded stands with lower competition. However, crowded stands have more and (or) larger trees, conferring greater capacity for aggregate absolute growth increases. Due to these contrasting effects, our models predicted that climate change will lead to greater stand-scale growth increases in stands with medium compared with low crowding but similar increases in stands with medium and high crowding. Thus, competition will mediate the impacts of climate change on individual- and stand-scale growth in important but complex ways.
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  • 97
    Publication Date: 2017-07-01
    Description: Beech bark disease (BBD) has demonstrable ecosystem consequences for eastern US forests stemming from American beech (Fagus grandifolia Ehrh.) mortality, often leading to increased dominance by its competitor, sugar maple (Acer saccharum Marsh.). We hypothesized that this BBD-induced shift in tree species composition leads to changes in soil acid–base chemistry, mediated through differences in leaf litter chemistry of the two species. Using a sequence of plots representing the progression of the disease in the Catskill Mountains, NY, USA, we examined the influence of tree species composition shift on soil chemistry. The BBD impact on tree species composition was confounded by variability in substrate (or nonexchangeable soil) calcium (Ca). While substrate Ca explained much of the variation in acid–base chemistry, increasing BBD was associated with increasing forest floor exchangeable Ca, sum of base cations, base saturation, cation-exchange capacity, and decreasing hydrogen. An apparent threshold effect of substrate Ca on sugar maple litter Ca concentration suggests that underlying soil Ca availability may contribute to the spatial extent and timeframe of BBD-induced shifts in species composition. The species compositional shift is a mechanism contributing to a vegetation effect on soil acid–base status and may partially counteract soil acidification in this acid deposition impacted region.
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  • 98
    Publication Date: 2015-08-01
    Description: Soil disturbance from organic matter loss and soil compaction can impair site productivity, but less is known about whether these disturbances also affect forest health (defined here as the presence and severity of damaging pests and diseases, mortality, and overall vigour). We used six long-term soil productivity (LTSP) sites in the interior of British Columbia, Canada to test the effects of organic-matter removal and soil compaction on forest health, and to explore the relationship between forest health response and potential indicators of site sensitivity: mineral soil pH, base saturation, carbon to nitrogen ratio (C:N), carbon to phosphorus ratio (C:P), and calcium to aluminum ratio (Ca:Al). Visual forest health surveys were conducted on 5400 15 and 20 year old lodgepole pine (Pinus contorta Dougl. ex Loud.) trees. Soil disturbance treatments significantly affected forest health metrics, but this response typically differed among sites. Principle component analyses indicated the response of healthy trees was negatively related to soil base saturation, the response of dead or dying trees related to soil C:P, and the response of tree disease related to soil Ca:Al, pH, base saturation, and C:N. We found forest health response to soil disturbance varied among sites with relationships between response and soil chemical properties, suggesting a greater vulnerability of pine stands to disease with increasing soil acidity.
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  • 99
    Publication Date: 2016-09-01
    Description: In this study, we tested the efficacy of establishing lodgepole pine (Pinus contorta Dougl.) from seed using woody mulch produced from slashed tree tops from a pine harvesting site; this mulch contained the closed serotinous cones of the lodgepole pine. Mulch was spread on prepared reclamation sites at depths of 0, 1, 3, and 5 cm. Broadcast seeding of pine was also done at mulch depths of 0 and 1 cm. Mulch cover that was 1 cm thick was the preferred treatment, as it produced 17 000 seedlings·ha−1 by the third year after treatment while being similar in seedling density to the 3 and 5 cm treatments. When 50 000 seeds·ha−1 were added, seedling density went up more on the sites with 1 cm of mulch than the sites with no mulch. Soil temperature was lower and temperature extremes were reduced under the mulch layer compared with the control plot. The plots with 1 cm of mulch also had higher soil moisture in the mineral layer than the plots with 0 cm of mulch. A thin layer of woody mulch, therefore, provided a source of pine seed and the covering of the ground provided a more benign environment for the establishment of pine germinants.
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  • 100
    Publication Date: 2017-12-01
    Description: We employed simulations by forest ecosystem (SIMA) and mechanistic wind damage (HWIND) models in upland boreal forests throughout Finland to study regional risks of wind damage under changing management preferences and climates (current and RCP4.5 and RCP8.5 scenarios) over 2010–2099. We used a critical wind speed for the uprooting of trees as a measure of vulnerability, which together with the probability of such wind speed defined a level of risk. Based on that, we also predicted the stem volume of growing stock at risk and the amount of damage. In this work, medium fertility sites were planted to one of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), or silver birch (Betula pendula Roth) or to the tree species that was dominant before the final clear-felling. The vulnerability to wind damage, the volume of growing stock at risk, and the amount of damage all increased, increasing the most in the south when the proportion of Norway spruce (with shallow rooting) of the growing stock increased. Under a severe climate warming, the proportion of Norway spruce decreased the most in the south, opposite to that of birch. This decreased the risk of damage in autumn (when birch is leafless), unlike in summer. The low risk of damage in the north was due to the large proportion of Scots pine.
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