ALBERT

Description: As support for the COSC drilling project (Collisional Orogeny in the Scandinavian Caledonides), an extensiveseismic survey took place during September and October 2014 in and around the newly drilled 2.5 km deepCOSC-1 borehole. The main aim of the COSC project is to better understand orogenic processes in past andrecently active mountain belts. For this, the Scandinavian Caledonides provide a well preserved case of Paleozoiccollision of the Laurentia and Baltica continental plates. Surface geology and geophysical data provide knowledgeabout the geometry of the Caledonian structure. The reflectivity geometry of the upper crust was imaged byregional seismic data and the resistivity structure by magnetotelluric methods. The crustal model was refined byseismic pre-site surveys in 2010 and 2011 to define the exact position of the first borehole, COSC-1.The completely cored COSC-1 borehole was drilled in Central Sweden through the Seve Nappe Complex, a partof the Middle Allochthon of the Scandinavian Caledonides that comprises units originating from the outer marginof Baltica. The upper 2350 m consist of alternating layers of highly strained felsic and calc-silicate gneissesand amphibolites. Below 1710 m the mylonite content increases successively and indicates a high strain zoneof at least 800 m thickness. At ca. 2350 m, the borehole leaves the Seve Nappe Complex and enters underlyingmylonitised lower grade metasedimentary units of unknown tectonostratigraphic position.The seismic survey consisted of three parts: a limited 3D-survey, a high resolution zero-offset VSP (verticalseismic profile) and a multi-azimuthal walkaway VSP (MSP) experiment with sources and receivers along threesurface profiles and receivers at seven different depth levels of the borehole. For the zero-offset VSP (ZVSP) ahydraulic hammer source was used and activated over a period of 20 s as a sequence of impacts with increasinghit frequency. The wave field was recorded with 3-component geophones and a receiver spacing of 2 m over thewhole borehole length.As first pre-processing steps, the three component VSP data were decoded and vertically stacked. Afterwards, theshots were merged to get a continuous shot gather. A horizontal rotation was performed, based on the S-wavearrivals.The rotated ZVSP-data show a high signal-to-noise ratio and good data quality. Signal frequencies up to 150 Hzwere observed. On the vertical component, clear direct P-wave arrivals are visible. Several P-wave reflectionsoccur below 1600 m logging depth. On both horizontal components, clear direct S-wave arrivals are visible afterrotation what suggests that the penetrated rock is anisotropic. In addition, several PS-converted waves can beidentified.In order to integrate the borehole data into the 3D surface seismic data, further processing concentrated only on theP-waves. First, deconvolution was applied to sharpen the signals and to suppress multiples. Then the wave field wasseparated into upgoing and downgoing components by median filtering. Finally, a corridor stack was generated us-ing the upgoing wave field in order to allow correlation with the borehole logging data and the surface seismic data.

Description: Berlin-Urban-Gradient is a ready-to-use imaging spectrometry dataset for multi-scale unmixing and hard classification analyses in urban environments. The dataset comprises two airborne HyMap scenes at 3.6 and 9 m resolution, a simulated spaceborne EnMAP scene at 30 m resolution, an im-age endmember spectral library and detailed land cover reference information. All images are pro-vided as geocoded reflectance products and cover the same subset along Berlin’s urban-rural gra-dient. The variety of land cover and land use patterns captured make the dataset an ideal play-ground for testing the transfer of methods and research approaches at multiple spatial scales.

Description: We present a new upper-mantle tomographic model derived solely from hum seismic data. Phase correlograms between station pairs are computed to extract phase-coherent signals. Correlograms are then stacked using the time–frequency phase-weighted stack method to build-up empirical Green's functions. Group velocities and uncertainties are measured in the wide period band of 30–250 s, following a resampling approach. Less data are required to extract reliable group velocities at short periods than at long periods, and 2 yr of data are necessary to measure reliable group velocities for the entire period band. Group velocities are first regionalized and then inverted versus depth using a simulated annealing method in which the number and shape of splines that describes the S-wave velocity model are variable. The new S-wave velocity tomographic model is well correlated with models derived from earthquakes in most areas, although in India, the Dharwar craton is shallower than in other published models.

Description: We investigated the crust and upper mantle of West Java, Indonesia by measuring the group velocity dispersion of surface waves. We analyzed waveform from four teleseismic earthquake recorded at three 3-component broadband seismometers. We analyzed fundamental mode of Rayleigh and Love waves from vertical, radial, and transverse components using multiple filter technique. We inverted the measured group velocity to obtain shear wave velocity profile down to 200 km depth. We observed low shear wave velocity zone at depth of about 20 km. Shear velocity reduction is estimated to be 18% compared to the upper and lower velocity layer. The low velocity zone might be associated with the subducting slab of Indo-Australian Plate as similar characteristics of low velocity zones also observed at other subducting regions.

Description: A temporally highly resolved reconstruction of sea-ice conditions in eastern Fram Strait, using the sea-ice proxy IP25, sheds new light on potential feedback mechanisms between sea-ice variability and ocean circulation changes during rapid deglacial climate shifts. While a post-LGM sea-ice maximum probably played an important role for the timing of Heinrich Event 1, distinct sea-ice discharge events seem to be intrinsically tied to perturbations in the oceanic overturning circulation. The herein presented sea-ice record is the hitherto only continuous documentation of sea-ice changes in the subpolar North Atlantic that covers the transition from the last glacial into the Holocene. These data strengthen the need for more studies of high-resolution sediment cores to better assess the short-term palaeoenvironmental development and the feedback mechanisms between sea-ice variability and oceanic/ atmospheric circulation fluctuations during this crucial time of climate change.

Description: Eine auf dem Meereisproxy IP25 basierende, zeitlich hochauflösende Rekonstruktion der Meereisbedingungen in der östlichen Framstraße wirft ein neues Licht auf mögliche Wechselwirkungen zwischen Meereisschwankungen und Veränderungen der Ozeanzirkulation während schneller deglazialer Klimaänderungen. Während ein post-LGM Meereismaximum wahrscheinlich eine wichtige Rolle für den Beginn von Heinrich- Ereignis 1 gespielt hat, scheinen Intervalle eines verstärkten Meereisexports untrennbar mit der Schwächung der ozeanischen Umwälzzirkulation verbunden zu sein. Der hier präsentierte Datensatz ist die bisher einzige durchgehende Dokumentation der Meereisveränderungen im subpolaren Nordatlantik während des Übergangs vom letzten Glazial in das Holozän. Diese Daten belegen den Bedarf an weiteren Studien an ähnlich zeitlich hochaufgelösten Sedimentkernabfolgen, um die kurzzeitige Entwicklung der Paläoumweltbedingungen und die Wechselwirkungen zwischen Meereisveränderungen und der ozeanisch/atmosphärischen Zirkulation während dieser Zeit häufiger Klimaschwankungen besser abschätzen zu können.

Description: Central elements of the TERENO network are “terrestrial observatories” at the catchment scale which were selected in climate sensitive regions of Germany for the regional analyses of climate change impacts. Within these observatories small scale research facilities and test areas are placed in order to accomplish energy, water, carbon and nutrient process studies across the different compartments of the terrestrial environment. Following a hierarchical scaling approach (point-plot-field) these detailed information and the gained knowledge will be transferred to the regional scale using integrated modelling approaches. Furthermore, existing research stations are enhanced and embedded within the observatories. In addition, mobile measurement platforms enable monitoring of dynamic processes at the local scale up to the determination of spatial pattern at the regional scale are applied within TERENO.

Description: In this extended abstract we motivate the development of the Flexible Hydrological Discharge Model (FHD-Model). We give a general overview on the FHD-Model’s function and – based on a selection of case studies – we illustrate its application in the framework of climate modelling studies at a global scale. Furthermore, we offer an outlook to upcoming applications and a following publication. The new FHD-Model is required, both, in the field of future climate projections and paleoclimatology. In these research areas, it satisfies the emerging need for flexible discharge transport schemes that react to sea level variations, which are related to variability and evolution of ice sheets. Furthermore, the FHD-Model easily adapts to variations in topography. Therefore, this discharge model is suitable for climate modelling studies on time scales that involve the evolution of land surface, ice sheets, discharge basins, and river systems.

Description: In diesem Beitrag legen wir unsere Motivation zur Entwicklung des Flexiblen Hydrologischen-Abfluss-Modells (FHD-Modell) dar. Wir geben einen Überblick über die Funktion des FHD-Modells und illustrieren – auf der Grundlage von ausgewählten Fallstudien – die Anwendung im Rahmen von globalen Klima-Modell-Studien. Weiterhin weisen wir auf zukünftige Anwendungen des Modells und eine anstehende Publikation hin. Das neue FHD-Modell wird im Zusammenhang mit Projektionen des zukünftigen Klimas und der Paläoklimatologie benötigt. In diesen Forschungsgebieten bedient es den sich abzeichnenden Bedarf an flexiblen kontinentalen Abfluss-Schemata, die auf die Änderung des Meeresspiegels reagieren können, der mit der Variabilität und Entwicklung von kontinentalen Eisschilden verknüpft ist. Darüber hinaus ist das FHD-Modell leicht für geographische Änderungen adaptierbar, die folgende Charakteristika umfassen: Landoberfläche, Eisschilde, Einzugsgebiete der Abflusssysteme, Flussläufe. Das FHD-Modell ist daher anwendbar für Zeitskalen, auf denen sich solche Eigenschaften der Erdoberfläche verändern.

Description: The Gulf of Cadiz and the passive continental margin of southern Iberia to the west of the Strait of Gibraltar locally accommodate the presently ongoing convergence between Africa and Eurasia by widespread, rather diffusive, seismic activity. Seismicity of the northern Gulf of Cadiz was derived from an amphibious seismological network, including 24 temporary marine offshore stations, besides the permanent networks in Portugal, Spain, and Morocco. During the 6 month of the offshore network operation, in total 86 local earthquakes were located at six or more offshore stations with the majority of earthquakes occurring to the southwest of Iberia and along the Algarve continental margin off southern Iberia. The distribution of events along the Algarve margin mimics features reported for the Atlantic passive continental margins of both South and North America. Focal mechanisms at the Portimão Bank support that seismically active areas are associated with compression. Similar stress patterns are reported for the east coast of South and North America. However, while earthquakes along the American east coast occur at crustal levels, earthquakes in the northern Gulf of Cadiz occur both in the lower crust and upper mantle, with the majority of events rupturing within the mantle, including a number of well-located earthquakes beneath crust forming the continent-ocean transition zone. The large number of earthquakes in the mantle might be caused by the unique geological setting, where deformation occurs in cool lithosphere of Mesozoic age. We suggest that seismicity along the Algarve margin is caused by re-activation of pre-existing margin-parallel faults rather than corresponding to newly formed structures related to a new developing plate boundary.

Description: The earthquake nucleation process has been vigorously investigated based on geophysical observations, laboratory experiments, and theoretical studies; however, a general consensus has yet to be achieved. Here, we studied nucleation process for the 2014 Iquique, Chile Mw 8.2 megathrust earthquake located within the current North Chile seismic gap, by analyzing a long-term earthquake catalog constructed from a cross-correlation detector using continuous seismic data. Accelerations in seismicity, the amount of aseismic slip inferred from repeating earthquakes, and the background seismicity, accompanied by an increasing frequency of earthquake migrations, started around 270 days before the mainshock at locations up-dip of the largest coseismic slip patch. These signals indicate that repetitive sequences of fast and slow slip took place on the plate interface at a transition zone between fully locked and creeping portions. We interpret that these different sliding modes interacted with each other and promoted accelerated unlocking of the plate interface during the nucleation phase.

Description: Monthly variations in the ratio of Rayleigh‐to‐Love waves in the secondary microseism are obtained from a colocated ring laser and an STS‐2 seismograph at Wettzell, Germany. Two main conclusions are derived for the Rayleigh‐to‐Love wave kinetic energy ratios in the secondary microseism; first, the energy ratio is in the range 0.8–0.9 (〈1.0) throughout a year except for June and July. It means that Love wave energy is larger than Rayleigh wave energy most of the year by about 10–20%. Second, this ratio suddenly increases to 1.0–1.2 in June and July, indicating a larger fraction of Rayleigh wave energy. This change suggests that the locations and behaviors of excitation sources are different in these months.

Description: Canga is a moderately hard iron-rich duricrust primarily composed of goethite as a result of the weathering of banded iron formations. Canga duricrusts lack a well-developed soil profile and consequently form an innate association with rupestrian plants that may become ferruginised, contributing to canga possessing macroscopic biological features. Examination of polished canga using a field emission scanning electron microscope (FE-SEM) revealed the biological textures associated with canga extended to the sub-millimetre scale in petrographic sections and polished blocks. Laminae that formed by abiotic processes and regions where goethite cements were formed in association with microorganisms were observed in canga. Biological cycling of iron within canga has resulted in two distinct forms of microbial fossilisation: permineralisation of multispecies biofilms and mineralisation of cell envelopes. Goethite permineralised biofilms frequently formed around goethite-rich kaolinite grains in close proximity to goethite bands and were composed of micrometre-scale rod-shaped, cocci and filamentous microfossils. In contrast, the cell envelopes immobilised by authigenic iron oxides were primarily of rod-shaped microorganisms, were not permineralised and occurred in pore spaces within canga. Complete mineralisation of intact rod-shaped casts and the absence of permineralisation suggested mineralised cell envelopes may represent fossilised iron-oxidising bacteria in the canga ecosystem. Replication of these iron-oxidising bacteria appeared to infill the porous regions within canga. Synchrotron-based Fourier transform infrared (FTIR) microspectroscopy demonstrated that organic biomarkers were poorly preserved with only weak bands indicative of aliphatic methylene (CH2) associated with permineralised microbial biofilms. High resolution imaging of microbial fossils in canga that had been etched with oxalic acid supported the poor preservation of organic biomarkers within canga, indicating mineralogical replacement of organic biomarkers.

Description: Hydrocarbons are abundant in anoxic environments and pose biochemical challenges to their anaerobic degradation by microorganisms. Within the framework of the Priority Program 1319, investigations funded by the Deutsche Forschungsgemeinschaft on the anaerobic microbial degradation of hydrocarbons ranged from isolation and enrichment of hitherto unknown hydrocarbon-degrading anaerobic microorganisms, discovery of novel reactions, detailed studies of enzyme mechanisms and structures to process-oriented in situ studies. Selected highlights from this program are collected in this synopsis, with more detailed information provided by theme-focused reviews of the special topic issue on ‘Anaerobic biodegradation of hydrocarbons' [this issue, pp. 1-244]. The interdisciplinary character of the program, involving microbiologists, biochemists, organic chemists and environmental scientists, is best exemplified by the studies on alkyl-/arylalkylsuccinate synthases. Here, research topics ranged from in-depth mechanistic studies of archetypical toluene-activating benzylsuccinate synthase, substrate-specific phylogenetic clustering of alkyl-/arylalkylsuccinate synthases (toluene plus xylenes, p-cymene, p-cresol, 2-methylnaphthalene, n-alkanes), stereochemical and co-metabolic insights into n-alkane-activating (methylalkyl)succinate synthases to the discovery of bacterial groups previously unknown to possess alkyl-/arylalkylsuccinate synthases by means of functional gene markers and in situ field studies enabled by state-of-the-art stable isotope probing and fractionation approaches. Other topics are Mo-cofactor-dependent dehydrogenases performing O2-independent hydroxylation of hydrocarbons and alkyl side chains (ethylbenzene, p-cymene, cholesterol, n-hexadecane), degradation of p-alkylated benzoates and toluenes, glycyl radical-bearing 4-hydroxyphenylacetate decarboxylase, novel types of carboxylation reactions (for acetophenone, acetone, and potentially also benzene and naphthalene), W-cofactor-containing enzymes for reductive dearomatization of benzoyl-CoA (class II benzoyl-CoA reductase) in obligate anaerobes and addition of water to acetylene, fermentative formation of cyclohexanecarboxylate from benzoate, and methanogenic degradation of hydrocarbons.

Description: Movie 7: "The abandonment of a CO2 storage site – pilot project Ketzin" (Length 10:39) Produktionsjahr: 2015

Description: Auf einer geologischen Verdachtsfläche in der Ortschaft Wallenhorst bei Bramsche wurden drei transient elektromagnetische (TEM) Profilmessungen über einem geologisch interessanten Gebiet durchgeführt. Dieses Gebiet wurde bereits mit anderen Messmethoden, passiver als auch aktiver Natur, untersucht. Zu diesen zählen unter anderem die Gleichstromgeoelektrik, Radiomagnetotellurik und die Eigenpotentialmethode, wie sie durch Gurk et al. [2013] verwendet wurden. Die TEM-Inversionsergebnisse der Messungen eines Profils werden hier vorgestellt.

Description: Application of the ambient noise surface wave tomography method (ANT) for determination of the upper-mantle structure requires data on long-periodic noise (T 〉 40 s). The ANT technique implies that noise sources are distributed almost uniformly over the surface. This is practically true for short-periodic noise, however, it is not so in the case of long periods. In this paper we show that the main contribution to noise at long periods is caused by signals from earthquakes. In some cases, they may strongly distort noise cross-correlation. This leads to an incorrect determination of surface wave velocity dispersion curves. To minimize such a distortion we propose two means: (1) to use records of noise for the periods when there is no clustering of earthquakes, such as aftershocks of strong events; (2) to stack cross-correlation functions for a period of at least three years in order to achieve sufficient uniformity of earthquake locations. Validity of this approach is demonstrated by ANT results for Europe. Tomographic reconstruction of Rayleigh wave group velocities for 10–100 s measured along interstation paths was carried out in a central part of Western Europe where resolving power of the data was the highest. Locally averaged dispersion curves were inverted to vertical S-wave velocity sections in this area. The results correspond closely to known features of the structure of the region, namely: strong difference of the crust and upper-mantle structure at the opposite sides from the Tornquist–Teisseyre Line down to ∼ 250 km, penetration of high-velocity material of East European Platform lithosphere under Carpathians, as well as penetration of low-velocity asthenospheric layer from the Carpathian region towards the northeast.

Description: In this study, we complement the notion of equilibrium states of the radiation belts with a discussion on the dynamics and time needed to reach equilibrium. We solve for the equilibrium states obtained using 1D radial diffusion with recently developed hiss and chorus lifetimes at constant values of Kp = 1, 3 and 6. We find that the equilibrium states at moderately low Kp, when plotted vs L-shell (L) and energy (E), display the same interesting S-shape for the inner edge of the outer belt as recently observed by the Van Allen Probes. The S-shape is also produced as the radiation belts dynamically evolve toward the equilibrium state when initialized to simulate the buildup after a massive dropout or to simulate loss due to outward diffusion from a saturated state. Physically, this shape, intimately linked with the slot structure, is due to the dependence of electron loss rate (originating from wave-particle interactions) on both energy and L-shell. Equilibrium electron flux profiles are governed by the Biot number (τDiffusion/τloss), with large Biot number corresponding to low fluxes and low Biot number to large fluxes. The time it takes for the flux at a specific (L, E) to reach the value associated with the equilibrium state, starting from these different initial states, is governed by the initial state of the belts, the property of the dynamics (diffusion coefficients), and the size of the domain of computation. Its structure shows a rather complex scissor form in the (L, E) plane. The equilibrium value (phase space density or flux) is practically reachable only for selected regions in (L, E) and geomagnetic activity. Convergence to equilibrium requires hundreds of days in the inner belt for E 〉 300 keV and moderate Kp (≤3). It takes less time to reach equilibrium during disturbed geomagnetic conditions (Kp ≥ 3), when the system evolves faster. Restricting our interest to the slot region, below L = 4, we find that only small regions in (L, E) space can reach the equilibrium value: E ~ [200, 300] keV for L = [3.7, 4] at Kp = 1, E ~ [0.6, 1] MeV for L = [3, 4] at Kp = 3, and E ~ 300 keV for L = [3.5, 4] at Kp = 6 assuming no new incoming electrons.

Description: We analyzed the noise recordings of a short-period seismic network to derive a shallow crustal S-wave velocity model at the Sumatra Fault in Northern Sumatra, Indonesia. By correlating the noise of 40 seismic stations' recording for 9 months, we could recover Rayleigh waves from vertical component recordings with sufficient signal-to-noise ratio. Group velocities of the Rayleigh waves could be determined in the period range from 0.71 to 4.4 s. These group velocities were used to invert for 2D group velocity maps at specific periods. Finally, the derived group velocity maps were inverted for a 3D S-wave velocity model. This model shows a region of a strong velocity decrease off the Great Sumatran Fault Zone, at the northeastern margin of the young Tarutung pull-apart basin. This observed low velocity block coincides with a caldera-like morphological feature which is interpreted as the surface expression of a hidden volcanic caldera. Considering the surface manifestations of geothermal activity around this anomaly, we conclude that the caldera is still acting as a heat source. On the other hand, the weak morphological expression at the surface indicates a certain age of the caldera which might be older than the Tarutung pull-apart basin. The findings provide important constraints on general concepts for the formation of pull-apart basins along the Sumatran fault and their relation to volcanism.

Description: In this study we present calculation of bounce resonant scattering of near equatorially mirroring electrons by fast magnetosonic waves. We first explore the sensitivity of the scattering rates and estimated time scales to a different number of resonances included into calculations. We then explore the sensitivity of calculated rates to the assumed wave normal angle. Our results show that at large radial distances bounce resonant scattering is capable of providing local isotropization of nearly equatorially mirroring electrons on the time scales as short as hours or even days depending on the assumed properties of waves. We also present analysis of the bounce frequencies of electrons and protons at various energies and radial distances and discuss the wave modes that are capable of bounce resonance with these particles. In particular, the importance of bounce resonance as a potential mechanism for the radiation belt remediation is discussed.

Description: The history of the Late Cenozoic stress regime was determined for an area between the gulfs of Fethiye and Antalya. Fault kinematic analysis and inversion of focal mechanisms of shallow earthquakes reveal significant evolution of the regional stress regime in SW Anatolia, i.e., the area of interaction between the Hellenic and Cyprus arcs, from the Mio-Pliocene to the present time. Fault kinematic analysis yields two different normal faulting stress regimes along the southwestern part of Fethiye-Burdur Fault zone, e.g., in and around Çameli Basin (Zone A1) and two different strike-slip to normal faulting stress regimes characterized by a roughly orthogonal set of extensional axes between Fethiye and Demre (Zone B) with an older NW–SE σ3 axis for Mio-Pliocene and a younger NE–SW σ3 axis for Plio-Quaternary time. Inversion of focal mechanisms of the earthquakes occurring in Zone A1 provides an extensional stress state with approximately N-S σ3 axis. Inversion of those occurring in Zone B, south of Zone A1, yields a dominantly strike-slip stress state with a NE-SW σ3 axis and a NW-SE σ1 axis respectively. The inversion slip vectors from fault planes yield a consistent normal faulting stress regime in Burdur Basin and its surroundings (i.e., along the northeastern part of Fethiye-Burdur Fault Zone, (Zone A2)) during Plio-Quaternary, continuing into recent time as indicated by earthquake focal mechanism inversions. Both states have a consistent NW–SE σ3 axis. Fault kinematic analysis indicates NW-SE extension acting in Zone C (subarea between Demre and Antalya), south of Zone A2, during Mio-Pliocene time. The inversion of focal mechanisms yields normal faulting also characterized by a consistent NW-SE σ3 axis. The nearly orthogonal extensional stress regimes (NW-SE and NE-SW) obtained by inversion of both measured and seismic faults seem to have been acting contemporaneously with each other at different intensities from the Mio-Pliocene onwards in SW Turkey. This may be attributed to the geodynamic effects related to the subduction of the African plate beneath Anatolia diffusing along the Hellenic and Cyprus arcs and in the west-southwestward extrusion of Anatolia. The cause of the early NW–SE extension is the slab-pull force due to the subduction process along the Cyprus arc, considered to be dominant until the Plio-Quaternary in the western part of the study area in zones A1 and B. The dominant status of the Cyprus arc continues today in the eastern part of study area in zones A2 and C. The later NE–SW to present day approximately N–S extension, dominant since the Plio-Quaternary, is related to the combined forces of the Anatolian extrusion and the subduction process along the Hellenic arc.

Description: In this study, seismic interferometry is used to analyze dynamic processes in the Earth’s shallow subsurface caused by environmental processes and ground shaking. In the first part of the thesis, the feasibility of a passive monitoring with ambient seismic noise at the pilot site for CO2 injection in Ketzin is investigated. Monitoring the expansion of the CO2 plume is essential for the characterization of the reservoir as well as the detection of potential leakage. From June 2008 until August 2013, more than 67000 tons of CO2 were injected into a saline aquifer at a depth of about 650 m. Passive seismic data recorded at a seismic network around the injection site was cross-correlated in a frequency range of 0.5-4.5 Hz over a period of 4 years. The frequency band of 0.5-0.9 Hz, in which surface waves exhibit a high sensitivity at the depth of the reservoir, is not suitable for monitoring purposes as it is only weakly excited. In a frequency range of 1.5-3 Hz, periodic velocity variations with a period of approximately one year are found that cannot be caused by the CO2 injection. The prominent propagation direction of the noise wave field indicates a wind farm as the dominant source providing the temporally stable noise field. This spacial stability excludes variations of the noise source distribution as a spurious cause of velocity variations. Based on an amplitude decrease associated with time windows towards later parts of the coda, the variations must be generated in the shallow subsurface. A comparison to groundwater level data reveals a direct correlation between depth of the groundwater level and the seismic velocity. The influence of ground frost on the seismic velocities is documented by a sharp increase of velocity when the maximum daily temperature stays below 0 C. Although the observed periodic changes and the changes due to ground frost affect only the shallow subsurface, they mask potential signals of material changes from the reservoir depths. To investigate temporal seismic velocity changes due to earthquake-related processes and environmental forcing in northern Chile, 8 years of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC) are analyzed. By autocorrelating the ambient seismic noise field, approximations of the Green’s functions are retrieved and velocity changes are measured with Coda Wave Interferometry. At station PATCX, seasonal changes of seismic velocity caused by thermal stress as well as transient velocity reductions are observed in the frequency range of 4-6 Hz. Sudden velocity drops occur at times of mostly earthquake-induced ground describing the seismic velocity variations based on continuous observations of the local ground acceleration. The model assumes that not only the shaking of large earthquakes causes velocity drops, but any small vibrations continuously induce minor velocity variations that are immediately compensated by healing in the steady state. The shaking effect is accumulated over time and best described by the integrated envelope of the ground acceleration over one day, which is the temporal resolution of the velocity measurements. In the model, the amplitude of the velocity reduction as well as the recovery time are proportional to the strength of the excitation. The increase of coseismic velocity change and recovery time with increasing excitation is confirmed by laboratory tests with ultrasound. Despite having only two free scaling parameters, the model fits the data of the shaking-induced velocity variation in remarkable detail. Additionally, a linear trend is observed that might be related to a recovery process from one or more earthquakes before the measurement period. A clear relationship between ground shaking and induced velocity reductions is not visible at other stations. The outstanding sensitivity of PATCX to ground shaking and thermal stress can be attributed to the special geological setting of the station, where the subsurface material consists of a relatively loose conglomerate with high pore volume leading to stronger nonlinearity compared to the other IPOC stations.

Description: In dieser Studie werden mit Hilfe von seismischer Interferometrie kleinste dynamische Prozesse in der Erdkruste beobachtet, welche beispielsweise durch umweltbedingte oder anthropogene Einflüsse sowie Bodenerschütterungen hervorgerufen werden können. Im ersten Teil der Arbeit werden Änderungen in der seismischen Geschwindigkeit am Pilotstandort für CO2-Speicherung in Ketzin untersucht. In einer Tiefe von 650m wurden dort zwischen Juni 2008 und August 2013 über 67000 Tonnen CO2 eingelagert. In einem Frequenzbereich vom 0,05-4,5 Hz wurden Kreuzkorrelationen des seismischen Hintergrundrauschens an einem kleinräumigen Netzwerk über einen Zeitraum von 4 Jahren berechnet. Der Frequenzbereich zwischen 0,5 und 0,9 Hz weist eine hohe Sensitivität von Oberflächenwellen in der Tiefe des Reservoirs auf, ist aber nur sehr schwach angeregt und eignet sich deswegen nicht für die Analyse. In einem Frequenzbereich von 1,5-3 Hz zeigen sich periodische Geschwindigkeitsänderungen mit einer Periode von einem Jahr, welche nicht durch die Einlagerung von CO2 erzeugt werden können. Eine Analyse des seismischen Hintergrundrauschens zeigt, dass dieses über den gesamten Zeitraum hinweg hauptsächlich aus der Richtung eines Windparks kommt. Durch die Stabilität des Wellenfeldes können Änderungen in den Quellpositionen, welche sich in scheinbaren Geschwindigkeitsänderungen zeigen können, ausgeschlossen werden. Eine Amplitudenabnahme der Geschwindigkeitsänderungen hin zu späteren Zeitfenstern in der Coda lässt auf oberflächennahe Prozesse als Ursache schließen. Ein Vergleich zwischen den jährlichen Geschwindigkeitsänderungen mit Schwankungen im Grundwasserspiegel zeigt eine direkte Korrelation. Ein sprunghafter Anstieg in der Geschwindigkeit zeigt sich im Winter, wenn die Tageshöchsttemperaturen unter den Gefrierpunkt sinken und der Boden zufriert. Obwohl Bodenfrost und Änderungen im Grundwasserspiegel nur einen sehr oberflächennahen Bereich betreffen, so überdecken sie dennoch mögliche Signale durch die Einlagerung von CO2. Im zweiten Teil der Arbeit werden Geschwindigkeitsänderungen in Nordchile untersucht, welche durch erdbebeninduzierte Prozesse und umweltbedingte Einflüsse hervorgerufen werden. Dazu wurden über einen Zeitraum von 8 Jahren Autokorrelationen des seismischen Hintergrundrauschens des IPOC Netzwerkes (Integrated Plate Boundary Observatory Chile) berechnet und mit seismischer Interferometrie ausgewertet. An der Station PATCX können in einem Frequenzbereich von 4-6 Hz periodische Geschwindigkeitsänderungen beobachet werden, welche durch thermisch induzierte Dehnung hervorgerufen werden. Außerdem treten transiente Geschwindigkeitsabnamen nach Bodenerschütterungen auf, welche hauptsächlich von Erdbeben verursacht werden. Die seismische Geschwindigkeit kehrt daraufhin langsam wieder auf ihr vorheriges Niveau zurück. Für die Geschwindigkeitsänderungen wurde ein empirisches Modell entwickelt, welches auf Messungen der lokalen Bodenerschütterung basiert. Dabei wird angenommen, dass nicht nur große erdbebeninduzierte, sondern auch kleinste Bodenerschütterungen einen Abfall der Geschwindigkeit erzeugen, welche wiederum innerhalb kürzester Zeit durch Heilung in den Gleichgewichtszustand zurückkehrt. Dabei summieren sich die Effekte durch die Bodenerschütterungen mit der Zeit auf und werden am besten mit dem Integral der lokalen Bodenbeschleunigung über die Messwerte eines Tages beschrieben. Die Diskretisierung von einem Tag entspricht der zeitlichen Auflösung in der Messung der Geschwindigkeitsänderungen. Sowohl die Amplitude der Geschwindigkeitsabnahme als auch die Zeit bis der Gleichgewichtszustand wieder erreicht ist (Heilungszeit) werden im Modell als proportinal zur Größe der Anregung angenommen. Eine Korrelation der Heilungszeit und der Amplitude der koseismischen Geschwindigkeitsabnahme mit der Größe der Anregung konnte mit Hilfe von Laboruntersuchungen mit Ultraschall bestätigt werden. Mit nur zwei Parametern beschreibt das Modell die transienten Geschwindigkeitsänderungen in bemerkenswerter Genauigkeit. Desweiteren beinhaltet das Modell einen linearen Verlauf in den Geschwindigkeitsänderungen, welcher vermutlich durch einen Heilungsprozess hervorgerufen wird, der auf ein oder mehrere Erdbeben vor dem Messzeitraum folgte. Eine Beziehung zwischen Bodenerschütterung und Geschwindigkeitsänderung ist an anderen Stationen des IPOC Netzwerkes nicht erkennbar. Die herausragende Sensitivität von PATCX im Hinblick auf Bodenerschütterung und thermische Dehnung kann den speziellen geologischen Gegebenheiten an der Station zugeschrieben werden. Bei dem dort vorliegenden Material handelt es sich um ein relativ loses Konglomerat mit großem Porenvolumen, welches ein starkes nichtlineares Verhalten aufweist, was an anderen IPOC Stationen nicht zu erwarten ist.

Description: We determined the three-dimensional shear wave velocity structure beneath the South Pacific superswell down to a depth of 200 km by analyzing fundamental Rayleigh wave records from permanent and temporary land-based and seafloor seismometers in the Pacific Ocean. Data from the Tomographic Investigation by seafloor ARray Experiment for the Society hotspot (TIARES) project yield excellent spatial resolution of velocity anomalies in the central part of the superswell, near the Society hotspot. Localized slow anomalies are found near hotspots in the upper mantle, but the vertical profiles of the anomalies vary from location to location: Slow anomalies near the Samoa, Macdonald, Pitcairn, and Society hotspots extend to at least 200 km depth, while a slow anomaly near the Marquesas hotspot extends only to ~150 km depth. Owing to the recently deployed seafloor array, horizontal resolutions of slow anomalies near the Society hotspot are substantially improved: The slow anomalies are about 300 km in lateral extent and have velocity anomalies as low as −6 %. The lithosphere thickness is estimated to be ~70 km in the vicinity of all hotspots, which may indicate thermal erosion by mantle plumes.

Description: Carbon from Earth’s interior is thought to be released to the atmosphere mostly via degassing of CO2 from active volcanoes1,2,3,4. CO2 can also escape along faults away from active volcanic centres, but such tectonic degassing is poorly constrained1. Here we use measurements of diffuse soil CO2, combined with carbon isotopic analyses to quantify the flux of CO2 through fault systems away from active volcanoes in the East African Rift system. We find that about 4 Mt yr−1 of mantle-derived CO2 is released in the Magadi–Natron Basin, at the border between Kenya and Tanzania. Seismicity at depths of 15–30 km implies that extensional faults in this region may penetrate the lower crust. We therefore suggest that CO2 is transferred from upper-mantle or lower-crustal magma bodies along these deep faults. Extrapolation of our measurements to the entire Eastern rift of the rift system implies a CO2 flux on the order of tens of megatonnes per year, comparable to emissions from the entire mid-ocean ridge system2,3 of 53–97 Mt yr−1. We conclude that widespread continental rifting and super-continent breakup could produce massive, long-term CO2 emissions and contribute to prolonged greenhouse conditions like those of the Cretaceous.

Description: Correlations of seismic noise are commonly used to monitor temporal variations of relative seismic velocity in period ranges from 1 s up to 100 s. Of particular interest is the detection of small changes in the order of 0.01–0.1 % in propagation speeds. Measuring such small differences can, however, be significantly biased by temporal variations in the properties of the noise sources within the corresponding frequency band. Using synthetic data, we show that apparent relative velocity variations might appear only due to changes in the amplitude and frequency content caused by source variations. Removing such unwanted effects by applying narrow bandpass filters in the preprocessing restricts the high-resolution analysis of any signal due to Gabor’s uncertainty limit, i.e., the correlation function suffers a limited resolution to time delay estimates for small correlation times, low-frequency ranges, and in narrow frequency bands. Better understanding of spatiotemporal noise source properties and the theoretical limitations of time–frequency analysis is critical for accurate and reliable passive monitoring.

Description: This thesis presents studies which address the regional-scale distribution of fluids during the seismic cycle in the subduction zone of Northern Chile. To infer the distribution of fluids, this work investigated the regional-scale electrical resistivity structure of the subduction zone. The resistivity structure was imaged and monitored using the magnetotelluric (MT) geophysical method. The analysed MT data were collected at nine permanent sites of the Integrated Plate Boundary Observatory Chile (IPOC) located along the forearc region in Northern Chile (21°-23.5°S, 69°-70°W). The regional-scale resistivity structure was derived by modelling long-period MT data using 3-D inversion approach. This model exhibits a complex resistivity structure, suggesting significant spatial variability in the fluid content at different regions of the subduction zone. The model shows that the continental South American plate within the forearc region is mainly characterized by high resistivities (〉1000 Ωm) between the coast and 69°W. The model shows additionally a number of regional low resistivity zones (LRZs, 〈10 Ωm) within the continental crust. Long-active fault zones and clusters of seismicity are observed within these LRZs, suggesting that these resistivity anomalies are relatively weak and permeable regions of the continental crust, where deformation processes and circulation of fluids have been focused over geologic time. Some of these LRZs reach the continental lower crust above the intraplate seismogenic zone, coinciding spatially with boundaries of the rupture area of large earthquakes and regional NW-SE structural lineaments. In the forearc mantle wedge the model exhibits a 150 km-long trench-parallel LRZ above the intermediate-depth seismogenic zone, suggesting significant along-strike variability in the amount of fluids released from the oceanic Nazca plate. The temporal evolution of the resistivity structure was monitored by analysing the IPOC MT data during 2007-2014. This analysis reveals anomalous temporal variations of the vertical magnetic transfer function (VTF) at one IPOC site. These anomalous variations were reproduced by modelling a decrease in resistivity within a seismically active region of the continental crust located above the interplate seismogenic zone. The spatiotemporal distribution of seismicity suggests that the inferred changes in resistivity were associated with episodes of upward migration of fluids generated at the plate interface. The sensitivity of MT data to changes in the resistivity structure and in the geomagnetic activity was evaluated. Possible regional-scale resistivity changes above the interplate seismogenic zone were simulated, obtaining that they can generate measurable variations in MT responses (TFs) recorded at the IPOC sites. However, the modelled variations in IPOC TFs can be masked by unwanted effects correlated with changes in magnetic fields generated in the atmosphere (source effects). The analysis of 18 years of geomagnetic data recorded at mid-latitude sites reveals that globally the VTF exhibits patterns related to source effects. Main patterns identified were periodical seasonal variations and a long-term trend correlated with the 11-year solar cycle. Such source effects can be identified as patterns observed synchronously in temporal variations of VTFs recorded at neighbouring sites, and which additionally show significant correlation with fluctuations of the geomagnetic activity.

Description: Within the framework of the multidisciplinary research project called INFLUINS, INtegrated FLUid dynamics IN Sedimentary basins, we use a highly sensitive magnetic field receiver based on Superconducting Quantum Interference Devices (SQUIDs) for the transient electromagnetic method and compare its performance specifications with a commercially available induction coil. Four fixed loops TEM measurements with 10 - 20 receiver stations each have been conducted along a survey line perpendicular to the known geologic strike direction at the test site Esperstedter Ried in Northern Thuringia, Germany. The signals of the SQUID receiver provide significantly better quality and are less affected by natural and man-made noise sources than the ones of the induction coil, which is proved by data error and noise measurement analysis. As a result, the 1D inverse modeling results of the SQUID data show lower misfit ratios and are more reliable compared to the coil.

Description: Earth science monitoring systems are distributed across Europe and the globe and measure the physicochemical characteristics of the planet under different geological regimes. The European Plate Observing System (EPOS) aims at creating a multidisciplinary pan-European data infrastructure for solid earth science to support a safe and sustainable society. In accordance with this scientific vision, the mission of EPOS is to integrate the diverse and advanced European Research Infrastructures for solid earth science relying on new e-science opportunities to monitor and unravel the dynamic and complex earth system. EPOS aims to enable innovative multidisciplinary research for a better understanding of the earth’s physical and chemical processes that control earthquakes, volcanic eruptions, ground instability and tsunami as well as the processes driving tectonics and earth’s surface dynamics. EPOS will improve our ability to better manage the use of the subsurface of the Earth. Through integration of data, models and facilities EPOS will allow the earth science community to make a step change in developing new concepts and tools for key answers to scientific and socio-economic questions concerning geo-hazards and geo-resources as well as earth sciences applications to the environment and to human welfare. EPOS brings together 24 European nations and combines national earth science facilities, the associated data and models together with the scientific expertise into a single e-infrastructure covering the whole geoscience domain and connects ten classes of geo-infrastructures, which have until now been handled separately, thus enabling an unprecedented level of scientific integration. This infrastructure will allow the earth sciences to achieve a step change in our understanding of the planet; it aims to enable us to prepare for geo-hazards and to responsibly manage the subsurface for infrastructure development, waste storage and the use of earth’s resources. With a European Research Infrastructure Consortium (ERIC) to be located in Rome (Italy), EPOS will provide an opportunity to maintain world-leading European earth sciences and represent a model for pan-European federated infrastructure currently being developed as ‘FAIR Principles’ for research data: Data should be Findable, Accessible, Interoperable and Re-usable (FORCE11, Wilkinson et al. 2016).

Description: Durch Messung der Spektralen Induzierten Polarisation (SIP) sollen Interpretationen der hydraulischen Eigenschaften des Untergrundes ermöglicht werden. Voraussetzung dafür ist, dass die Abhängigkeit der elektrischen Parameter von der Geometrie des Porenraumes und damit von der hydraulischen Leitfähigkeit bekannt ist und diese nicht durch die chemischen Eigenschaften des Porenfluids verändert werden. In dieser Arbeit liegt der Fokus speziell auf dem Einfluss der Salinität und des pH-Wertes des Porenfluids auf SIP Messungen.

Description: To investigate interaction and feedback mechanisms of different climate components in the Arctic, we use a regional atmosphere-ocean model setup, consisting of the global ocean – sea-ice model MPIOM with high resolution in the Arctic coupled to the regional atmosphere model REMO. We perform an experiment using reanalysis data from the European Center of Medium Range Weather Forecast (ERA-40) as external forcing to simulate the climate of the last decades (1958–2001). We analyze this experiment in order to improve our understanding of ocean – sea-ice – atmosphere processes at the marginal ice zone in the Greenland-Iceland-Norwegian (GIN) Sea. We present first results on the variability of the marginal ice zone in GIN Sea, where in the last century the commonly named Arctic Odden has been observed frequently, an ice tongue with large daily variability in size and shape. We are interested in the dynamics of the formation of such a sea-ice tongue and show that in our model advection of ice rather than new ice formation is the driving mechanism.

Description: Um das Zusammenspiel und Rückkopplungseffekte zwischen den arktischen Klimakomponenten zu analysieren, verwenden wir ein regional gekoppeltes Atmosphären – Ozean-Modell, bestehend aus dem globalen Ozean – Meereis-Modell MPIOM mit hoher regionaler Auflösung in der Arktis und dem regionalen Atmosphärenmodel REMO. Als Randdaten für dieses Modell verwenden wir Reanalyse-Daten (ERA-40) des europäischen Zentrums für mittelfristige Wettervorhersagen ECMWF und simulieren das Klima der letzten Dekaden (1958–2001). Wir präsentieren erste Ergebnisse über die Meereisvariabilität in der Grönland-Island-Norwegen-See, in der im letzten Jahrhundert regelmäßig der sogenannte arktische Odden, eine Zunge aus Meereis mit großer täglicher Variabilität in Größe und Form, beobachtet wurde. Diese Eiszunge hat direkten Einfluss auf den Wärme- und Salzhaushalt in dieser Region und dadurch auf die Dynamik der darunterliegenden Wassermassen und die Tiefenwasserproduktion. Wir sind daran interessiert, wie solche arktischen Odden entstehen und zeigen, dass in unserem Modell eher Advektion von Eis als Bildung von neuem Eis der zugrunde liegende Mechanismus ist.

Description: The Halmahera island belongs to the North Moluccas province (Maluku Utara), Indonesia. This K-shaped island is located in the eastern part of the Moluccas Sea, the only active arc-arc collision complex on the Earth. The western arm of the K forms a volcanic arc due to the former subduction of the Moluccas Sea plate underneath Halmahera. The region is characterized by intense seismic activity at crustal, intermediate depth, and along the subducting plate. At crustal level the Halmahera seismicity along the two eastern arms of the K show strike-slip faulting style. In November 2015 a localized intense and energetic seismic activity started around Jailolo volcano in the West Halmahera Regency. The seismic sequence intermittently lasted until February 2016 and hundreds of events were felt by the population and several buildings were destroyed and damaged by the shaking. The largest shocks of the sequence have been located by global seismicity networks (GEOFON and GCMT) showing normal faulting style. The temporal evolution of the seismicity seems to be more swarm-like type activity instead of mainshock-aftershock sequence. In spring 2016 a research project has been funded by the German's Humanitarian program in collaboration with BMKG, Indonesia, with the goal of understanding the origin of the intense seismic activity and the related hazard. In summer 2016 we instrumented the area with a dense seismic network composed of 29 short period and 6 broad-band seismometers. The instrument deployment aims at characterizing the seismicity of the Jailolo region in relationship with the 2015-2016 seismic activity. The network will help to understand the seismo-tectonic of the area and the relation between seismicity and the volcanic activity at Jailolo volcano and possible link with the 2015-2016 swarm. Should the seismic activity intensify as in November 2015, we can record it and narrow down the underlying physical mechanisms. Waveform data are available from the GEOFON data centre, under network code 7G, and are embargoed until the end of 2021.

Description: In this paper, a new probabilistic seismic hazard assessment (PSHA) is presented for Peninsular India. The PSHA has been performed using three different recurrence models: a classical seismic zonation model, a fault model, and a grid model. The development of a grid model based on a non-parameterized recurrence model using an adaptation of the Kernel-based method that has not been applied to this region before. The results obtained from the three models have been combined in a logic tree structure in order to investigate the impact of different weights of the models. Three suitable attenuation relations have been considered in terms of spectral acceleration for the stable continental crust as well as for the active crust within the Gujarat region. While Peninsular India has experienced large earthquakes, e.g., Latur and Jabalpur, it represents in general a stable continental region with little earthquake activity, as also confirmed in our hazard results. On the other hand, our study demonstrates that both the Gujarat and the Koyna regions are exposed to a high seismic hazard. The peak ground acceleration for 10 % exceedance in 50 years observed in Koyna is 0.4 g and in the Kutch region of Gujarat up to 0.3 g. With respect to spectral acceleration at 1 Hz, estimated ground motion amplitudes are higher in Gujarat than in the Koyna region due to the higher frequency of occurrence of larger earthquakes. We discuss the higher PGA levels for Koyna compared Gujarat and do not accept them uncritically.

Description: This study examines time-dependent inner core structures using waveforms and double differential times of the PKP(bc–df) and PKP(ab–df) phases measured from repeating earthquakes in the southwest Pacific subduction zones. Repeating earthquakes can eliminate potential artefacts of interevent distance and improve the measurement precision of temporal changes in PKPdf phases due to differential rotation of the Earth's inner core. PKPdf waves from the southwest Pacific primarily sample the eastern hemisphere of the inner core along equatorial paths. Time separation of repeating earthquakes ranges from 4 to 14.4 yr. Most observed double differential times of PKP(bc–df) and PKP(ab–df) are within ±70 ms, with no systematic changes as a function of time separation or calendar time. Null temporal changes of the PKPdf wave could indicate a smooth regional-scale lateral velocity gradient in the eastern hemisphere of the inner core. Uncertainties in the data prohibit statistically meaningful estimates of the lateral velocity gradient, temporal trend, inner core differential rotation rate, or decadal oscillations. Synthetic seismograms are used to test the effects of several possible artefacts and to quantify the magnitudes of velocity perturbations relative to previous estimates. These artefacts are quantitatively assessed to determine their expected effects on the measurements.

Description: This document provides information on the site effects studies carried out in Kyrgyzstan. These studies are carried out within the Global Change Observatory Central Asia of the GFZ and the Earthquake Model Central Asia (EMCA). Furthermore, the site effects estimated using different approaches are incorporated into the probabilistic seismic hazard assessment (PSHA) for Bishkek.

Description: A temporary seismic network was installed in Sri Lanka for a time period of 13 months. The stations were equipped with Earth Data EDR-210 digital recorders and Trillium 120 PA, Güralp C3E and Güralp CMG-3ESP broadband sensors. Main aim of the network is to shed light on the crustal and upper mantle structure beneath the island. Also local seismic activity is studied. Waveform data are available from the GEOFON data centre, under network code 1A, and are embargoed until July 2021.(Grant-Number: GIPP201616 ) * Description is taken from seismic metadata, and may not match the preferred title for citations.

Description: The Gulf of California formed by oblique divergence across the Pacific–North America plate boundary. This presentation combines numerical forward modeling and plate tectonic reconstructions in order to address 2 important aspects of rift dynamics: (1) Plate motions during continental rifting are decisively controlled by the non-linear decay of rift strength. This conclusion is based on a recent plate-kinematic analysis of post-Pangea rift systems (Central Atlantic, South Atlantic, Iberia/Newfoundland, Australia/Antarctica, North Atlantic, South China Sea). In all cases, continental rifting starts with a slow phase followed by an abrupt acceleration within a few My introducing a fast rift phase. Numerical forward modeling with force boundary conditions shows that the two-phase velocity behavior and the rapid speed-up during rifting are intrinsic features of continental rupture that can be robustly inferred for different crust and mantle rheologies. (2) Rift strength depends on the obliquity of the rift system: the force required to maintain a given rift velocity can be computed from simple analytical and more realistic numerical models alike, and both modeling approaches demonstrate that less force is required to perpetuate oblique extension. The reason is that plastic yielding requires a smaller plate boundary force when extension is oblique to the rift trend. Comparing strike slip and pure extension end‐member scenarios, it can be shown that about 50% less force is required to deform the lithosphere under strike‐slip. This result implies that rift systems involving significant obliquity are mechanically preferred. These two aspects shed new light on the underlying geodynamic causes of Gulf of California rift history. Continental extension is thought to have started in Late Eocene/Oligocene times as part of the southern Basin and Range Province and evolved in a protracted history at low extension rate (≤15 mm/yr). However, with a direction change in Baja California microplate motion 13-6 My ago, plate divergence drastically increased its obliquity, which reduced the rifts mechanical resistance to extension. This effective loss of rift strength sparked an acceleration of the Gulf of California rift and ultimately enabled today’s divergence velocities of more than 45 mm/yr.

Description: The Alliance of Science Organizations in Germany recommends scientific institutions to disclose payments of Open Access publication fees to make the cost structure of the Open Access publication market clearly recognizable.

Description: The description of the Open Access transition, its mechanisms and actors, assigns a central role to libraries in this process and names various activities libraries may choose to actively observe their exposed role in the transition process. In this context the following recommendations are formulated: 1. Strategic and practical anchorage of open-access in the information provisioning of academic libraries. 2. Anchorage of Open Access in the licensing practice. It seems reasonable to close nationwide agreements with Open Access providers on general terms and conditions for scientific publishing in Open Access for all German scholarly institutions (Offsetting-contracts, APC-Framework contracts). Libraries can negotiate such agreements for themselves or participate in nationwide options. 3. Financing publication fees for Open Access journals (APCs) through acquisition budgets. This will successively ensue a shifting of funds from subscriptions in the acquisition departments to Open Access. A raise of funds for financing subscription fees out of the libraries’ own budgets or third party sponsoring (e.g. Open Access publication fund of the Deutsche Forschungsgemeinschaft) should only be necessary on an interim basis, if at all. 4. Cross-institutional disclosure (open books) of subscription and Open Access fees as well as key data (ratios) on publication and related cash flow between academic institutions and publishers in Germany. The aim is to support the development of transparent markets and price-structures for scientific publishing. 5. Installation of efficient and scalable processes and services at libraries to organize coverage (of the costs) for Open Access articles by academic authors.

Description: Determining thin layer thickness is very important for reservoir characterization and CO2 quantification. Given its high time-frequency resolution and robustness, the complex spectral decomposition method was applied on time-lapse 3D seismic data from the Ketzin pilot site for CO2 storage to evaluate the frequency-dependent characteristics of thin layers at the injection level. Higher temporal resolution and more stratigraphic details are seen in the all-frequency and monochromatic reflectivity amplitude sections obtained by complex spectral decomposition compared to the stacked sections. The mapped geologic discontinuities within the reservoir are consistent with the preferred orientation of CO2 propagation. Tuning frequency mapping shows the thicknesses of the reservoir sandstone and gaseous CO2 is consistent with the measured thickness of the sandstone unit from well logging. An attempt to discriminate between pressure effects and CO2 saturation using the extracted tuning frequency indicates that CO2 saturation is the main contributor to the amplitude anomaly at the Ketzin site. On the basis of determined thickness of gaseous CO2 in the reservoir, quantitative analysis of the amount of CO2 was performed and shows a discrepancy between the injected and calculated CO2 mass. This may be explained by several uncertainties, like structural reservoir heterogeneity, a limited understanding of the complex subsurface conditions, error of determined tuning frequency, the presence of ambient noise and ongoing CO2 dissolution.

Description: In this report information on the residential exposure, and its vulnerability is provided orderto better understand the expected consequences of the seismic risk in Kyrgyzstan, with thefinal aim of further improving the existing normative.

Description: The distribution of damage due to recent earthquakes has shown that the effects of shallow geological structures on the level of ground shaking represent an important factor in engineering seismology. Whereas many previous studies have estimated site amplification factors in the frequency domain, their application to the real‐time modeling of ground motion is not yet fully established. In this article, a method for the real‐time correction of frequency‐dependent site‐response factors is proposed, which accounts not only for the modulus, but also for the changes in the signal phase related to local site conditions. The transformation of the complex standard spectral ratios to a causal recursive filter in the time domain allows for the forecasting of the waveforms for soft‐soil sites almost in real time when the signal is recorded earlier at a reference site. When considering travel‐time differences of the various seismic phases between the hypocenter and the studied sites, the level of ground motion at soft‐soil sites with respect to arrival time, energy, duration, and frequency content can be well constrained, even in cases of a high spatial variability of the amplification patterns.

Description: More than 15,000 seismic events were recorded by the Israel Seismic Network (ISN) during the past 30 years, at the vicinity of the Dead Sea fault (DSF) zone. During those years, locations were obtained using several velocity models, which resulted in inconsistent locations. In addition, we found that seismicity is biased to very shallow depth estimations that do not match other estimations of more localized studies in the region. This study is focused on improving the regional earthquake catalog using robust single‐event location software (within the Antelope software), based on two seismic velocity models: (1) a local model (Gitterman et al., 2005) and (2) a global model (Kennett and Engdahl, 1991). The relocated events show more reasonable depth distributions, in accordance with the seismotectonic settings of the region, and the local velocity model shows smaller location errors than the global velocity model, suggesting better convergence of the location solutions. We also demonstrate and analyze the difference in the event‐station distribution, showing location effects of a sparse network, in which the main effect is seen for the focal depths: events located out of the network coverage tend to obtain a focal depth shallower than events located within the network coverage. The depth cross section along the DSF zone, within the boundaries of this study, presents a good correlation with previous estimation of the boundaries of the seismogenic zone, obtained by heat‐flow analysis. The relocated earthquake catalog is regarded as the new initial robust locations of the seismic bulletin of the ISN and considered as the basis for future studies and for more elaborated relocations; it is open to the public and can be downloaded from the Geological Survey of Israel website at https://www.gsi.gov.il (last accessed December 2015).

Description: The tropospheric horizontal gradients with high spatiotemporal resolutions provide important information to describe the azimuthally asymmetric delays and significantly increase the ability of ground-based GNSS (Global Navigation Satellite Systems) within the field of meteorological studies, like the nowcasting of severe rainfall events. The recent rapid development of multi-GNSS constellations has potential to provide such high-resolution gradients with a significant degree of accuracy. In this study, we develop a multi-GNSS process for the precise retrieval of high-resolution tropospheric gradients. The tropospheric gradients with different temporal resolutions, retrieved from both single-system and multi-GNSS solutions, are validated using independent numerical weather models (NWM) data and water vapor radiometer (WVR) observations. The benefits of multi-GNSS processing for the retrieval of tropospheric gradients, as well as for the improvement of precise positioning, are demonstrated. The multi-GNSS high-resolution gradients agree well with those derived from the NWM and WVR, especially for the fast-changing peaks, which are mostly associated with synoptic fronts. The multi-GNSS gradients behave in a much more stable manner than the single-system estimates, especially in cases of high temporal resolution, benefiting from the increased number of observed satellites and improved observation geometry. The high-resolution multi-GNSS gradients show higher correlation with the NWM and WVR gradients than the low-resolution gradients. Furthermore, the precision of station positions can also be noticeably improved by multi-GNSS fusion, and enhanced results can be achieved if the high-resolution gradient estimation is performed, instead of the commonly used daily gradient estimation in the multi-GNSS data processing.

Description: When applying the Global Navigation Satellite System (GNSS) for precise kinematic positioning in airborne and shipborne gravimetry, multiple GNSS receiving equipment is often fixed mounted on the kinematic platform carrying the gravimetry instrumentation. Thus, the distances among these GNSS antennas are known and invariant. This information can be used to improve the accuracy and reliability of the state estimates. For this purpose, the known distances between the antennas are applied as a priori constraints within the state parameters adjustment. These constraints are introduced in such a way that their accuracy is taken into account. To test this approach, GNSS data of a Baltic Sea shipborne gravimetric campaign have been used. The results of our study show that an application of distance constraints improves the accuracy of the GNSS kinematic positioning, for example, by about 4 mm for the radial component.

Description: The objective of this study is the development and application of a full flood risk chain, appropriate for the large scale and based on long term and continuous simulation. The novel approach of ‘derived flood risk based on continuous simulations’ is introduced, where the synthetic discharge time series is used as input into flood impact models and flood risk is directly derived from the resulting synthetic damage time series.

Description: The open-source mantle convection code ASPECT (Computational Infrastructure for Geodynamics) provides a robust foundation for numerically examining a wide range of geodynamic processes. ASPECT’s strength arises from its massive scalability, use of AMR (adaptive mesh refinement), advanced solvers, community support and modular design, the latter of which permits straightforward modification of discrete components of the code, such as constitutive relationships. Here, we present preliminary work that uses such adaptions to model long-term tectonic problems (lithospheric and upper mantle dynamics) with ASPECT. Crustal- and lithospheric-scale deformation is modeled using a recently implemented visco-plastic constitutive relationship, with viscous flow characterized by diffusion and/or dislocation creep and plastic failure following a Drucker-Prager yield criterion model. Distinct compositional layers and their associated material properties are tracked through field- or tracer-based methods, which also allow tracking of time-dependent properties such as accumulated strain. Preliminary 2-D models of long-term (〉 10 Myr) continental extension successfully reproduce results of prior studies with rift basin structure largely dependent on initial lithospheric structure, extension velocity and strain-softening parameterization. Building on these preliminary results, our presentation will focus on ASPECT’s viability and performance for modeling long-term tectonics within the context of 2-D vs. 3-D simulations, CPU scaling, distinct solver methods, adaptive mesh refinement and field- vs. tracer-based methods. Our primary goal in addressing these topics is to highlight ASPECT’s current functionality and address key areas of future development associated with modeling long-term tectonics. Additionally, we hope to spur discussion regarding a long-term tectonics benchmark that addresses the strong resolution-dependence of simulations using plasticity formulations based on the Drucker-Prager yield criterion.

Description: Foreshock activity is considered as one of the most promising precursory changes for the main shock prediction in the short term. Averaging over several foreshock sequences has shown that foreshocks are characterized by distinct 3D patterns: their epicenters move towards the main shock epicenter, event count accelerates, and b-value drops. However, these space–time-size patterns were verified so far only in a very few individual cases mainly due to inadequate seismicity catalogue data. We have investigated 3D foreshock patterns before the M w 8.8 Maule in 27 February 2010, M w 8.1 Iquique in 1 April 2014, and M w 8.4 Illapel in 16 September 2015 great earthquakes in the Chile subduction zone. To avoid biased results, no a priori spatiotemporal definitions of foreshocks were inserted. The procedure was based on pattern recognition from statistically significant seismicity changes in the three domains. The pattern recognition in one domain was independent of the pattern recognition in another domain. We found and verified with two independent catalogue data sets (CSN, IPOC) that within a critical area of ca. 65 km from the main shock epicenter, the 2014 event was preceded by distinct foreshock 3D patterns. A nearly weak foreshock stage (20 January–14 March 2014) was followed by a main-strong stage (15 March–1 April 2014) highly significant in all domains, although foreshock activity slightly decreased in about the last 5 days. Seismic moment release also accelerated in the last stage due to the occurrence of a cluster of very strong foreshock events. Foreshock activity very likely occurred in the hanging-wall fault domain on the South American Plate overriding Nazca Plate. The 2014 foreshock activity was quite similar to the one preceding the 6 Apr. 2009 L’ Aquila (Italy) M w 6.3 earthquake associated with normal faulting. Using the 2014 earthquake as a reference event, we observed that similar foreshock 3D patterns preceded the 2010 and 2015 earthquakes within critical distances of about 170 and 50 km, respectively. However, the foreshock activities were only weak in both the cases likely because of poor catalogue completeness.

Description: This publication compiles the operational data (flow rate, cumulative mass, density, injection temperature, electrical conductivity and in-well pressure data) recorded during a field experiment on brine injection at the Ketzin pilot site during October 2015 to January 2015. Anyone should feel free to make use of the published data for any ethical purpose (civil use) – for example for process modelling and engineering.

Description: The Central Andean Plateau (CAP), as defined by elevations in excess of 3 km, extends over 1800 km along the active South American Cordilleran margin making it the second largest active orogenic plateau on Earth. The uplift history of this high Plateau, with an average elevation around 4 km above sea level, remains uncertain as paleoelevation studies along the CAP suggest a complex, nonuniform uplift history. As part of the Central Andean Uplift and the Geodynamics of High Topography (CAUGHT) project, we image the S wave velocity structure of the crust and upper mantle using surface waves measured from ambient noise and teleseismic earthquakes to investigate the upper mantle component of plateau uplift. We observe three main features in our S wave velocity model including (1) a positive velocity perturbation associated with the subducting Nazca slab; (2) a negative velocity perturbation below the sub‐Andean crust that we interpret as anisotropic Brazilian cratonic lithosphere; and (3) a high‐velocity feature in the mantle above the slab that extends along the length of the Altiplano from the base of the Moho to a depth of ~120 km. A strong spatial correlation exists between the lateral extent of this high‐velocity feature and the relatively lower elevations of the Altiplano basin suggesting a potential relationship. Determining if this high‐velocity feature represents a small lithospheric root or foundering of orogenic lithosphere requires more integration of observations, but either interpretation implies a strong geodynamic connection with the uppermost mantle and the current topography of the northern CAP.

Description: The inner core under Africa is thought to be a region where the nature of inner core texture changes: from the strongly anisotropic ‘western’ part of the inner core to the weakly anisotropic, or isotropic ‘eastern’ part of the inner core. Additionally, observations of a difference in isotropic velocity between the two hemispheres have been made. A very large new dataset of simultaneous PKPdf and PKPbc observations, on which differential travel times have been measured, is used to examine the upper 360 km of the inner core under Europe, Africa and the surrounding oceans. Inversion of the differential travel time data for laterally varying inner core anisotropy reveals that inner core anisotropy is stronger under central Africa and the Atlantic Ocean than under the western Indian Ocean. No hemispherical pattern is present in Voigt isotropic velocities, indicating that the variation in anisotropy is due to differing degrees of crystal alignment in the inner core, not material differences. When anisotropy is permitted to change with depth, the upper east-most part of the study region shows weaker anisotropy than the central and western regions. When depth dependence in the inner core is neglected the hemisphere boundary is better represented as a line at 40°E than one at 10°E, however, it is apparent that the variation of anisotropy as a function of depth means that one line of longitude cannot truly separate the more and less anisotropic regions of the inner core. The anisotropy observed in the part of the inner core under Africa which lies in the ‘western’ hemisphere is much weaker than that under central America, showing that the western hemisphere is not uniformly anisotropic. As the region of low anisotropy spans a significant depth extent, it is likely that heterogeneous heat fluxes in the core, which may cause variations in inner core anisotropy, have persisted for several hundred million years.

Description: In-situ EXAFS combined with a Paris-Edinburgh press (PEP) is an outstanding tool to investigate the local environment of trace elements in melts at high pressure and temperature. A novel design of the pressure assembly ensures a highly stable experimental setup (reaching temperatures of up to 2000 K at 2.5 GPa) while permitting the necessary level of X- ray transmission. This study focuses on the structural incorporation of the geochemically important trace elements Y and Sr in sodium-rich silicate-carbonate melts. Y and Sr K edge EXAFS were collected in transmission mode of the melt (at ~2.5 GPa, 1600 K) and its respective quench products. Distinct changes in the XANES region suggest a change in site symmetry during the cooling process.

Description: In dieser Arbeit wurde erstmals eine KMS-820 Empfangsapparatur von KMS Technologies für In-Loop TEM-Messungen im typischen Zero-TEM-Zeitbereich eingesetzt. Dabei wurden Vergleichsmessungen in der Kölner Umgebung mit dem GDP32-II von Zonge Engineering durchgeführt. Am Institut für Geophysik und Meteorologie der Universität zu Köln wird seit Jahren der GDP32-II als Empfänger für TEM-Messungen verwendet, sodass dieses Gerät und seine Eigenschaften bereits bekannt sind und sich die Ergebnisse gut als Referenz für Vergleiche mit der neuen KMS-820 Empfangseinheit eignen. Das KMS-820 System ist für eine allgemeine Anwendung in der Elektromagnetik und Mikroseismik entwickelt worden. Zur Zeit ist der Haupteinsatz in der Magnetotellurik und LOTEM Sondierung.

Description: During the processing of magnetotelluric (MT) data, frequency-dependent, complex transfer functions between magnetic (B) and electric (E) fields are calculated. The transfer functions provide information about the conductivity of the subsurface and thus are of crucial importance. In some cases the data processing proves to be difficult, since the recorded time series can be heavily contaminated by anthropogenic noise signals, e. g. galvanic currents or near field sources. Several methods, like robust or remote reference processing, address these problems, however in case of coherent noise sources they might fail (Junge, 1996). Therefore a new multivariate processing scheme based on an eigenvalue decomposition method (Egbert, 1997) was developed within an AMT study in the Westerwald, Germany (Hering, 2015). The results are presented for frequencies between 10 Hz and 5 kHz. The choice of the noise model is crucial for noise being coherent between different channels at a local site but incoherent to that at remote sites. For an unfavorable signal-to-noise ratio, however, the results of the eigenvalue analysis might be misleading, e. g. if the two dominant eigenvalues are taken as an indication for homogeneous source fields. Furthermore the magnetic and electric field polarizations from the Westerwald data set were analyzed. The results show distinct preferential directions and may be related to artificial source fields. As a consequence the far field assumption has to be checked for subsequent data interpretation.

Description: Many German lakes experienced significant water level declines in recent decades that are not fully understood due to the short observation period. At a typical northeastern German groundwater-fed lake with a complex basin morphology, an acoustic sub-bottom profile was analysed together with a transect of five sediment cores, which were correlated using multiple proxies (sediment facies, μ-XRF, macrofossils, subfossil Cladocera). Shifts in the boundary between sand and mud deposition were controlled by lake level changes, and hence, allowed the quantification of an absolute lake level amplitude of ~8 m for the Holocene. This clearly exceeded observed modern fluctuations of 1.3 m (AD 1973–2010). Past lake level changes were traced continuously using the calcium-record. During high lake levels, massive organic muds were deposited in the deepest lake basin, whereas lower lake levels isolated the sub-basins and allowed carbonate deposition. During the beginning of the Holocene (〉9700 cal. a BP), lake levels were high, probably due to final melting of permafrost and dead-ice remains. The establishment of water-use intensive Pinus forests caused generally low (3–4 m below modern) but fluctuating lake levels (9700–6400 cal. a BP). Afterwards, the lake showed an increasing trend and reached a short-term highstand at c. 5000 cal. a BP (4 m above modern). At the transition towards a cooler and wetter late Holocene, forests dominated by Quercus and Fagus and initial human impact probably contributed more positively to groundwater recharge. Lake levels remained high between 3800 and 800 cal. a BP, but the lake system was not sensitive enough to record short-term fluctuations during this period. Lake level changes were recorded again when humans profoundly affected the drainage system, land cover and lake trophy. Hence, local Holocene water level changes reflect feedbacks between catchment and vegetation characteristics and human impact superimposed by climate change at multiple temporal scales.

Description: Berlin-Urban-Gradient is a ready-to-use imaging spectrometry dataset for multi-scale unmixing and hard classification analyses in urban environments. The dataset comprises two airborne HyMap scenes at 3.6 and 9 m resolution, a simulated spaceborne EnMAP scene at 30 m resolution, an image endmember spectral library and detailed land cover reference information. All images are provided as geocoded reflectance products and cover the same subset along Berlin’s urban-rural gradient. The variety of land cover and land use patterns captured make the dataset an ideal playground for testing the transfer of methods and research approaches at multiple spatial scales.

Description: Moment Tensors (MTs) provide important information for seismotectonic, stress distribution and source studies. It is also important as a real time or near real time information in shakemaps, tsunami warning, and stress transfer. Therefore a reliable and rapid MT computation is a routine task for modern seismic networks with broadband sensors and real-time digital telemetry. In this paper we present the database of Moment Tensor solutions computed during the last ten years in Western Greece by the University of Patras, Seismological Laboratory (UPSL). The data from UPSL broad band network were used together with the ISOLA Moment Tensor inversion package for routine MT calculation. The procedures followed and the comparison of UPSL derived solutions with the ones provided by other agencies for Western Greece region are presented as well. The Moment Tensor database includes solutions for events in the magnitude range 2.8–6.8 and provides a unique insight into the faulting characteristics of Western Greece. Moreover it paves the way for detailed studies of stress tensor and stress transfer. The weak events' Moment Tensor included in UPSL's database are important for the comprehension of local seismotectonics and reveal the role of minor faults, which may be critical in seismic hazard estimation.

Description: The recent expansion of dense GPS networks over plate boundaries allows for remarkably precise mapping of interseismic coupling along active faults. The interseismic coupling coefficient is related to the ratio between slipping velocity on the fault during the interseismic period and the long-term plates velocity, but the interpretation of coupling in terms of mechanical behavior of the fault is still unclear. Here, we investigate the link between coupling and seismicity over the Chilean subduction zone that ruptured three times in the last 5 years with major earthquakes (Maule Mw 8.8 in 2010, Iquique Mw 8.1 in 2014 and Illapel Mw 8.4 in 2015). We combine recent GPS data acquired over the margin (38°–18°S) with older data to get the first nearly continuous picture of the interseismic coupling variations on the subduction interface. Here, we show that at least six low coupling zones (LCZ), areas where coupling is low relatively to the neighboring highly coupled segments can be identified. We also find that for the three most recent Mw 〉 8 events, co-seismic asperities correlate well with highly coupled segments, while LCZs behaved as barriers and stopped the ruptures. The relation between coupling and background seismicity in the interseismic period before the events is less clear. However, we note that swarm sequences are prone to occur in intermediate coupling areas at the transition between LCZ and neighboring segments, and that the background seismicity tends to concentrate on the downdip part of the seismogenic locked zone. Thus, highly coupled segments usually exhibit low background seismicity. In this overall context, the Metropolitan segment that partly ruptured during the 2015 Illapel earthquake appears as an outlier since both coupling and background seismicity were high before the rupture, raising the issue of the remaining seismic hazard in this very densely populated area.

Description: On April 1st, 2014, a Mw 8.2 (U.S. Geological Survey moment magnitude) earthquake occurred in the subduction zone offshore northern Chile. In the two weeks leading up to the earthquake, a sequence of foreshocks, starting with a Mw 6.7 earthquake on March 16th and including three more Mw 6.0+ events, occurred predominantly south of the April 1st mainshock epicenter and up-dip of the area of significant slip during the mainshock. Using earthquake locations and source parameters derived in a previous study (Hayes et al., 2014) and a Coulomb failure stress change analysis of these events, we assess in detail the hypothesis that the earthquakes occurred as a cascading sequence, each event successively triggering the next, ultimately triggering the rupture of the mainshock. Following the initial Mw 6.7 event, each of the three largest foreshocks (Mw 6.4, 6.2 and 6.3), as well as the hypocenter of the mainshock, occurred in a region of positive Coulomb stress change produced by the preceding events, indicating these events were brought closer to failure by the prior seismicity. In addition, we reexamine the possibility that aseismic slip occurred and what role it may have played in loading the plate boundary. Using horizontal GPS displacements from along the northern Chile coast prior to the mainshock, we find that the foreshock seismicity alone likely does not account for the observed signals. We perform a grid search for the location and magnitude of an aseismic slip patch that can account for the difference between observed signals and foreshock-related displacement, and find that a slow slip region with slip corresponding to a Mw ∼ 6.8 earthquake located coincident with or up-dip of the foreshock seismicity can best explain this discrepancy. Additionally, such a slow slip region positively loads the mainshock hypocentral area, enhancing the positive loading produced by the foreshock seismicity.

Description: Collecting magnetotelluric data in Greenland give rise to different challenges. Here we investigate one of the challenges, how a fjord system connected to the ocean can affect induction arrows around the fjord, by numerical simulations for periods of 1s, 10s and 100s. The results are induction arrows from a magnetotelluric data set collected in West Greenland in the summer 2013, with stations along the shoreline of the fjords between the towns of Kangerlussuaq and Aasiaat, see Figure 1. The setup consisted of 10 LMT stations on a 100 km profile with equipment kindly supplied by the GIPP at GFZ Potsdam (2015).

Description: Raschke (2016) commented on Mak et al. (2015) regarding the use of the performance metric, calculation of the epicentral intensity, and treatment of the focal depths for historical earthquakes when the focal depths have not been estimated in the databases we used. In reply, we present our opinions on these issues. We hope this may help the reader to decide how our study should be interpreted and how future studies of similar kinds should be conducted.

Description: The study area is located between the Jan Mayen Ridge and the east coast of Greenland. It has a complex geological setting with the ultraslow Kolbeinsey and Mohns spreading ridges, the anomalously shallow Eggvin Bank, the Jan Mayen Microcontinent (JMMC), and the tectonically active West Jan Mayen Fracture Zone (WJMFZ). In this study, we present the results of forward 3D structural, S-wave velocity, and gravity modeling which provide new insights into the deep crust and mantle structure and the wide-ranging influence of the Iceland Plume. The crustal parts of the presented 3D structural model are mainly constrained by local seismic refraction and reflection data. Accordingly, greatest crustal thicknesses (24 km) are observed on the northern boundary of the JMMC, while the average crustal thickness is 8.5 km and 4 km in the Kolbeinsey and Mohns Ridge, respectively. The densities of the crustal parts are from previous studies.Additionally, the mantle density is derived from S-wave velocity data (between 50 and 250 km depth), while densities of the lithospheric mantle between the Moho and 50km are calculated assuming isostatic equilibrium at 250km depth. This is used as a starting density model which is further developed to obtain a reasonable fit between the calculated and measured (free-air) gravity fields. The observed S-wave tomographic data and the gravity modeling prove that the Iceland plume anomaly in the asthenosphere affects the lithospheric thickness and temperature, from the strongly influenced Middle Kolbeinsey Ridge, to the less affected North Kolbeinsey Ridge (Eggvin Bank), and to the little impacted Mohns Ridge. Thus, the age-temperature relations of the different mid-ocean ridges of the study area are perturbed to different degrees controlled by the distance from the Iceland Plume. Furthermore, we find that the upper 50 km of lithospheric mantle are thermally affected by the plume only in the southwestern parts of the study area.

Description: Closely-spaced receiver-function profiles in the east-central India–Tibet collision zone reveal drastic west–east changes of the crustal and upper mantle structure. West of ∼91.5°E, we show the Indian crust-mantle boundary (Moho) extending subhorizontally from ∼50 km depth below sea level under the High Himalaya to ∼90 km under the central Lhasa terrane. Further north, this boundary transitions to become the top of the Indian lithospheric mantle and, becoming faint but still observable, it can be tracked continuously to ∼135 km depth near ∼31.5°N. The top of the Indian lithospheric mantle is clearly beneath the Tibetan Moho that is also a conspicuous boundary, undulatory at 60–75 km depth from the central Lhasa terrane to the north end of our profile at ∼34°N. This geometry is consistent with underthrusting of Indian lower crust and underplating of the Indian plate directly beneath southern Tibet. In contrast, east of ∼91.5°E, the Indian Moho is only seen under the southernmost margin of the Tibetan plateau, and eludes imaging from ∼50 km south of the Yarlung-Zangbo suture to the north. The Indian lower crust thins greatly and in places lacks a clear Moho. This is in contrast to our observation west of ∼91.5°E, that the Indian lower crust thickens northwards. A clear depression of the top of the Indian lower crust is also observed along west–east oriented profiles, centered above the region where the Indian Moho is not imaged. Our observations suggest that roll-back of the Indian lithospheric mantle has occurred east of ∼91.5°E, likely due to delamination associated with density instabilities in eclogitized Indian lower crust, with the center of foundering beneath the southern Lhasa terrane slightly east of 91.5°E.

Description: The rupture processes of the 2015 April 25 Gorkha earthquake and its strongest aftershock occurred on May 12 in Nepal are investigated by joint inversion of seismological and geodetic data. Synthetic test shows that the sedimentary layers in the source region play an important role in the rupture process inversion. Our optimized model of the mainshock shows that the rupture has a unilateral propagation pattern. The dominant mechanism is pure thrust with maximum slip of 5.8 m, the rupture scale extends ~ 60 km along dip and ~ 150 km along strike, and the largest static stress change is ~ 7.6 MPa. The total seismic moment is 7.87 × 1020 N m, equivalent to Mw 7.9. Most seismic moment was released within 80 s and the majority seismic moment was released at the first 40 s. The rupture propagated in main slip asperity with a velocity of ~ 3.0 km/s. The strong aftershock magnitude is about Mw 7.3, and the peak slip is about 5.0 m, close to the peak slip of the mainshock. Moreover, the slips of the mainshock and the aftershocks are in good complementary, suggesting a triggering relationship between them. Considering the strain accumulation, the Gorkha earthquake ruptured only part of the seismic gap alone, thus still poses high earthquake risk, especially in the west side of the mainshock rupture zone.

Description: Earth currents were first observed in the middle of the 19th century, closely related to magnetic field variations. Particularly the magnetic storms of 1859, which belong to the strongest ones ever experienced, destroying telegraphic constructions in the USA, Europe and Australia, made Johann von Lamont start with experiments about the nature and origin of earth currents. Among these experiments he presented for the first time a method to calculate the thickness of a high conductivity layer in southern Germany.

Description: Impressed Current Cathodic Protection (ICCP) systems are extensively used for the protection of central Europe‘s dense network of oil-, gas- and water pipelines against destruction by electrochemical corrosion. Protection is provided by the injection of a DC current into the pipeline (Figure 2). However, occasional pipeline integrity surveys demand the protection current to be switched on- and off periodically. The resulting time varying pipe current induces secondary electric- and magnetic fields in the surrounding earth. While these fields are usually considered to be unwanted cultural noise, we aim at utilizing these fields for EM exploration, since the switching cycles typical fundamental periods roughly correspond to periods used in controlled source EM applications (CSEM).

Description: We reconstructed 3300 years (3500 BCE and 200 BCE) of the development history of the Rąbień peatland located in central Poland, using pollen, macrofossil, testate amoebae, Cladocera, Chironomidae and geochemistry. Central Europe, particularly Poland, is characterised by a transitional climate that is influenced by continental and Atlantic air masses, which makes this region very sensitive to climate change. Our results demonstrate the high potential of the Rąbień peat record to reconstruct palaeohydrological dynamics. The studied time interval is characterised by two pronounced dry periods: from ~ 2500 to ~ 1700 BCE and from ~ 700 to ~ 500 BCE, and two significant increases in the water table: from ~ 1000 to ~ 800 BCE and from ~ 500 to ~ 250 BCE. The timing of the wet shift at 600 BCE corresponds to wet periods at different sites in Central and Eastern Europe. Our investigation reveals a more complicated and complex than previously assumed set of climatic relationships in Europe between 3500 BCE and 200 BCE, which might be linked through complex teleconnections of atmospheric circulation patterns. Only reconstructions that are based on an understanding of current observations from peatlands and lake ecosystems may lead to a better interpretation of past climate changes.

Description: Three-dimensional joined inversion of topography, gravity and geoid data was carried out in the collision zone between the Eurasian and Arabian plates, comprising Central and Eastern Anatolia, the Black Sea Basin and the Caucasus region. The 3D algorithm, first introduced by Motavalli-Anbaran et al. (2013), is based on a Bayesian approach with Gaussian density functions in which the targeted area is divided into vertical columns, each comprised of four layers namely water (of known thickness i.e. bathymetry) if present, crust, lithospheric mantle, and asthenosphere. The inversion results are Moho depth, average crustal density and depth to the lithosphere–asthenosphere boundary, defined here as the 1350 °C isotherm. Existing seismic Moho depths were used as a priori information in order to constrain crustal thicknesses. Thickest crust (up to 50 km) was found underneath the Great Caucasus Mountains, thinnest crust (22–25 km) underneath the Black Sea Basin. The East-Anatolian plateau is underlain by relatively thick crust (up to 45 km), thinning to less than 40 km towards the Central Anatolian Plateau. Eastern Anatolia and the eastern part of Central Anatolia are underlain by strongly thinned lithosphere (up to 100 km). Thickest lithosphere (up to 200 km) underlies the Caspian Basin and the Russian Platform.

Description: Research data are the basis for scientific research and often irreplaceable (e.g. observational data). Storage of such data in appropriate, theme specific or institutional repositories is an essential part of ensuring their long term preservation and access. The free and open access to research data for reuse and scrutiny has been identified as a key issue by the scientific community as well as by research agencies and the public. To ensure the datasets to intelligible and usable for others they must be accompanied by comprehensive data description and standardized metadata for data discovery, and ideally should be published using digital object identifier (DOI). These make datasets citable and ensure their long-term accessibility and are accepted in reference lists of journal articles (http://www.copdess.org/statement-of-commitment/). The GFZ German Research Centre for Geosciences is the national laboratory for Geosciences in Germany and part of the Helmholtz Association, Germany’s largest scientific organization. The development and maintenance of data systems is a key component of ‘GFZ Data Services’ to support state-of-the-art research. The datasets, archived in and published by the GFZ Data Repository cover all geoscientific disciplines and range from large dynamic datasets deriving from global monitoring seismic or geodetic networks with real-time data acquisition, to remotely sensed satellite products, to automatically generated data publications from a database for data from micro meteorological stations, to various model results, to geochemical and rock mechanical analyses from various labs, and field observations. The user-friendly presentation of published datasets via a DOI landing page is as important for reuse as the storage itself, and the required information is highly specific for each scientific discipline. If dataset descriptions are too general, or require the download of a dataset before knowing its suitability, many researchers often decide not to reuse a published dataset. In contrast to large data repositories without thematic specification, theme-specific data repositories have a large expertise in data discovery and opportunity to develop usable, discipline-specific formats and layouts for specific datasets, including consultation to different formats for the data description (e.g., via a Data Report or an article in a Data Journal) with full consideration of international metadata standards.

Description: Numerical modeling is a powerful tool to investigate the response of high-enthalpy geothermal systems to production, yet few studies have examined the long-term evolution and thermal structure of these systems. Here we report a series of numerical simulations of fluid flow and heat transfer around magmatic intrusions which reveal key features of the natural thermal and hydraulic structures of high-enthalpy geothermal systems. We explore the effect of key geologic controls, such as host rock permeability, the emplacement depth and geometry of the intrusion, and temperature-dependent permeability near the intrusion, on the depth and extent of boiling zones, the number and spatial configuration of upflow plumes, and how these aspects evolve over the systems’ lifetime. Host rock permeability is a primary control on the general structure, temperature distribution and extent of boiling zones, as systems with high permeability (≥10−14 m2) show shallow boiling zones restricted to ≤1 km depth, while intermediate permeability (∼10−15 m2) systems display vertically extensive boiling zones reaching from the surface to the intrusion. Intrusion emplacement depth is a further control, as intermediate permeability systems driven by an intrusion at ≥3 km depth only show boiling above 1 km. If a cooling intrusion becomes permeable at temperatures significantly in excess of the critical temperature of water, the enthalpy of the upflow becomes high enough that systems with high permeability show vertically extensive boiling zones, and intermediate permeability systems spatially extensive zones of supercritical water near the intrusion. The development of multiple, spatially separated upflow plumes above a single intrusive body is characteristic of systems with high permeability and deep emplacement depth. Depending on the primary geologic controls, systems exhibit characteristic lateral and vertical gradients in pressure, temperature and enthalpy relative to the intrusive heat source which may aid in geothermal exploration and interpretation of field measurements.

Description: DESMEX (Deep electromagnetic sounding for mineral exploration) ist ein Verbundprojekt, das vom Bundesministerium für Bildung und Forschung im Rahmen der Fördermaßnahme r – Innovative ⁴ Technologien für Ressourceneffizienz – Forschung zur Bereitstellung wirtschaftsstrategischer Rohstoffe gefördert wird. Primäres Ziel des Projektes ist die Entwicklung neuer geophysikalischer Verfahren für die Erkundung von heimischen Rohstoffpotenzialen, im Speziellen von Erzen. Im besonderen Fokus steht die Entwicklung zur flächenhaften und möglichst hochausflösenden Abdeckung durch elektromagnetische Verfahren mit Eindringtiefen bis 1000 Metern Tiefe. Weiterhin sollen bekannte Lagerstätten sowie bekannte Datensätze neu bewertet und Konzepte entwickelt werden zur Erfassung von bisher unbekannten Rohstoffvorkommen, beispielsweise von Hochtechnologiemetallen, die bisher nicht Gegenstand der Bergbauaktivitäten waren. Als Untersuchungsgebiet wurde das ostthüringer Schiefergebirge in der Gegend von Schleiz bis Greiz ausgewählt, da hier das Vorkommen von antimonitführenden Gängen bekannt ist.

Description: During the past decade, the relevance of research data stewardship has been rising significantly and data publication has become more familiar. Preservation of research data for long-term use, including its storage in adequate repositories has been identified as a key issue by the scientific community as well as by research agencies and the public. In practice, however, the current state of data sharing and re-use requires considerable improvement. This paper reviews recent developments in this area, and aims to provide some guidance to the increasing diversity of newly developed digital solutions, such as data journals, online data repositories, and citable digital object identifier (DOI) for datasets. We examine the differences and similarities between different examples of Arctic-related data management, including the newly created database of the Global Terrestrial Network for Permafrost GTN-P, a Canadian example of a (meta)data portal (Polar Data Catalogue), and examples of data repositories (e.g., PANGAEA, Nordicana D) and data journals (e.g., Earth System Science Data). We also describe the newly established Registry of Research Data Depositories (re3data.org) as a convenient resource for individual researchers to get an overview on and identify an appropriate repository for their scientific datasets as well for funding agencies during the evaluation process of the data management plan of research proposals.

Description: In den letzten zehn Jahren ist die Bedeutung des Zugangs und der Nachnutzung von Forschungsdaten gestiegen. Neue Publikationsstrategien für Forschungsdaten stellen sicher, dass wissenschaftliche Daten dauerhaft in geeigneten Daten-Repositorien gespeichert und zugänglich gemacht werden können. Auch wenn die Umsetzung dieser Publikationsstrategien von der wissenschaftlichen Community und von Forschungsförderorganisationen als zentrale Herausforderung für das Wissenschaftssystem benannt wird, ergeben sich in der Praxis noch viele Herausforderungen. Dieser Artikel gibt einen Überblick über aktuelle Entwicklungen im Bereich des Forschungsdatenmanagements. Exemplarisch werden einige Beispiele für den offenen Zugang vorgestellt und Publikationsstrategien für Forschungsdaten beschrieben. U.a. werden Aufgabe und Dienstleistung von Daten-Repositorien, Daten-Journalen sowie Daten-Portalen im Bereich der Arktisforschung erläutert. Exemplarisch werden folgende digitale Forschungsdateninfrastrukturen vorgestellt: Das kanadische (Meta)daten-Portal Polar Data Catalogue, die neue Datenbank des Global Terrestrial Network for Permafrost GTN-P (Metadaten und Daten), die Daten-Repositorien PANGAEA und Nordicana D sowie das Daten-Journal Earth System Science Data (ESDD). Darüber hinaus wird der Service des Registry of Research Data Repositories (re3data. org) vorgestellt. Dieses internationale Verzeichnis unterstützt Forschende und Forschungsförderer bei der Identifikation von geeigneten Daten-Repositorien zur Speicherung und Zugänglichmachung ihrer Forschungsdaten.

Description: Diffusion rates and associated deformation behaviour in olivine have been subjected to many studies, due to the major abundance of this mineral group in the Earth’s upper mantle. However, grain boundary (GB) transport studies yield controversial results. The relation between transport rate, energy, and geometry of individual GBs is the key to understand transport in aggregates with lattice preferred orientation that favours the presence and/or alignment of specific GBs over random ones in an undeformed rock. In this contribution, we perform classical molecular dynamics simulations of a series of symmetric and one asymmetric tilt GBs of Mg 2 SiO 4 Mg2SiO4 forsterite, ranging from 9.58° to 90° in misorientation and varying surface termination. Our emphasis lies on unravelling structural characteristics of high- and low-angle grain boundaries and how the atomic structure influences grain boundary excess volume and self-diffusion processes. To obtain diffusion rates for different GB geometries, we equilibrate the respective systems at ambient pressure and temperatures from 1900 to 2200 K and trace their evolution for run durations of at least 1000 ps. We then calculate the mean square displacement of the different atomic species within the GB interface to estimate self-diffusion coefficients in the individual systems. Grain boundary diffusion coefficients for Mg, Si and O range from 10 −18 10−18 to 10 −21 m 3 10−21m3 /s, falling in line with extrapolations from lower temperature experimental data. Our data indicate that higher GB excess volumes enable faster diffusion within the GB. Finally, we discuss two types of transport mechanisms that may be distinguished in low- and high-angle GBs.

Description: Cosmic rays are the highest-energy particles found in nature. Measurements of the mass composition of cosmic rays with energies of 1017–1018 electronvolts are essential to understanding whether they have galactic or extragalactic sources. It has also been proposed that the astrophysical neutrino signal1 comes from accelerators capable of producing cosmic rays of these energies2. Cosmic rays initiate air showers—cascades of secondary particles in the atmosphere—and their masses can be inferred from measurements of the atmospheric depth of the shower maximum3 (Xmax; the depth of the air shower when it contains the most particles) or of the composition of shower particles reaching the ground4. Current measurements5 have either high uncertainty, or a low duty cycle and a high energy threshold. Radio detection of cosmic rays6, 7, 8 is a rapidly developing technique9 for determining Xmax (refs 10, 11) with a duty cycle of, in principle, nearly 100 per cent. The radiation is generated by the separation of relativistic electrons and positrons in the geomagnetic field and a negative charge excess in the shower front6, 12. Here we report radio measurements of Xmax with a mean uncertainty of 16 grams per square centimetre for air showers initiated by cosmic rays with energies of 1017–1017.5 electronvolts. This high resolution in Xmax enables us to determine the mass spectrum of the cosmic rays: we find a mixed composition, with a light-mass fraction (protons and helium nuclei) of about 80 per cent. Unless, contrary to current expectations, the extragalactic component of cosmic rays contributes substantially to the total flux below 1017.5 electronvolts, our measurements indicate the existence of an additional galactic component, to account for the light composition that we measured in the 1017–1017.5 electronvolt range.

Description: The Namibian continental margin marks the starting point of the Tristan da Cunha hotspot trail, the Walvis Ridge. This section of the volcanic southwestern African margin is therefore ideal to study the interaction of hotspot volcanism and rifting, which occurred in the late Jurassic/early Cretaceous. Offshore magnetotelluric data image electromagnetically the landfall of Walvis Ridge. Two large-scale high resistivity anomalies in the 3-D resistivity model indicate old magmatic intrusions related to hot-spot volcanism and rifting. The large-scale resistivity anomalies correlate with seismically identified lower crustal high velocity anomalies attributed to magmatic underplating along 2-D offshore seismic profiles. One of the high resistivity anomalies (above 500 Ωm) has three arms of approximately 100 km width and 300 km to 400 km length at 120° angles in the lower crust. One of the arms stretches underneath Walvis Ridge. The shape is suggestive of crustal extension due to local uplift. It might indicate the location where the hot-spot impinged on the crust prior to rifting. A second, smaller anomaly of 50 km width underneath the continent ocean boundary may be attributed to magma ascent during rifting. We attribute a low resistivity anomaly east of the continent ocean boundary and south of Walvis Ridge to the presence of a rift basin that formed prior to the rifting.

Description: The hydrological budget of a region is determined based on the horizontal and vertical water fluxes acting in both inward and outward directions. These integrated water fluxes vary, altering the total water storage and consequently the gravitational force of the region. The time-dependent gravitational field can be observed through the Gravity Recovery and Climate Experiment (GRACE) gravimetric satellite mission, provided that the mass variation is above the sensitivity of GRACE. This study evaluates mass changes in prominent reservoir regions through three independent approaches viz. fluxes, storages, and gravity, by combining remote sensing products, in-situ data and hydrological model outputs using WaterGAP Global Hydrological Model (WGHM) and Global Land Data Assimilation System (GLDAS). The results show that the dynamics revealed by the GRACE signal can be better explored by a hybrid method, which combines remote sensing-based reservoir volume estimates with hydrological model outputs, than by exclusive model-based storage estimates. For the given arid/semi-arid regions, GLDAS based storage estimations perform better than WGHM.

Description: The formation and destruction of supercontinents requires prolonged convergent tectonics between particular plates, followed by intra-continental extension during subsequent breakup stages. A specific feature of the Late Paleozoic supercontinent Pangea is the prolonged and diachronous formation of the collisional belts of the Rheic suture zone coeval with recurrent continental breakup and subsequent formation of the mid-ocean ridge systems of the Paleo- and Neo-Tethys oceans at the Devonian and Permian margins of the Gondwana plate, respectively. To decide whether these processes are causally related or not, it is necessary to accurately reconstruct the plate motion of Gondwana relative to Laurussia. Here we propose that the strain pattern preserved in the continental crust can be used for the reconstruction of ancient plate kinematics. We present Euler pole locations for the three fundamental stages of the Late Paleozoic assembly of Pangea and closure of the Rheic Ocean: (I) Early Devonian (ca. 400 Ma) collisional tectonics affected Gondwana at the Armorican Spur north of western Africa and at the promontory of the South China block/Australia of eastern Gondwana, resulting in the Variscan and the Qinling orogenies, respectively. The Euler pole of the rotational axis between Gondwana and Laurussia is positioned east of Gondwana close to Australia. (II) Continued subduction of the western Rheic Ocean initiates the clockwise rotation of Gondwana that is responsible for the separation of the South China block from Gondwana and the opening of Paleo-Tethys during the Late Devonian. The position of the rotational axis north of Africa reveals a shift of the Euler pole to the west. (III) The terminal closure of the Rheic Ocean resulted in the final tectonics of the Alleghanides, the Mauritanides and the Ouachita–Sonora–Marathon belt, occurred after the cessation of the Variscan orogeny in Central Europe, and is coeval with the formation of the Central European Extensional Province and the opening of Neo-Tethys at ca. 300 Ma. The Euler pole for the final closure of the Rheic Ocean is positioned near Oslo (Laurussia). Thus, the concomitant formation of convergent and divergent plate boundaries during the assembly of Pangea is due to the relocation of the particular rotational axis. From a geodynamic point of view, coupled collisional (western Pangea) and extensional tectonics (eastern Pangea) due to plate tectonic reorganization is fully explained by slab pull and ridge push forces.

Description: We investigate theoretical limits on detection and reliable estimates of source characteristics of small earthquakes using synthetic seismograms for shear/tensile dislocations on kinematic circular ruptures and observed seismic noise and properties of several acquisition systems (instrument response, sampling rate). Simulated source time functions for shear/tensile dislocation events with different magnitudes, static stress drops, and rupture velocities provide estimates for the amplitude and frequency content of P and S phases at various observation angles. The source time functions are convolved with a Green's function for a homogenous solid assuming given P, S wave velocities and attenuation coefficients and a given instrument response. The synthetic waveforms are superposed with average levels of the observed ambient seismic noise up to 1 kHz. The combined seismograms are used to calculate signal-to-noise ratios and expected frequency content of P and S phases at various locations. The synthetic simulations of signal-to-noise ratio reproduce observed ratios extracted from several well-recorded data sets. The results provide guidelines on detection of small events in various geological environments, along with information relevant to reliable analyses of earthquake source properties.

Description: Clastic-organic varved sediments from the boreal Lake Kalliojärvi, Central Finland, record changes in snow accumulation for more than 4000 years. The varve record was reconstructed using digital image analysis from 4132 varve yr BP to present with 2.2% counting error and is supported by paleomagnetic data. Two laminae are identified in a typical varve structure: (1) the minerogenic lamina, which accumulates during spring as a result of catchment erosion triggered by spring floods and (2) the organic lamina, which is composed of allochthonous and autochthonous organic matter that accumulates during summer, autumn, and winter. The minerogenic influx is related to variations in snow accumulation and follows the different phases of the North Atlantic Oscillation (NAO). Decreased snow accumulation is related to a weakened NAO phase. Thus, the minerogenic influx record provides additional information about NAO variation. The Fe/Mn ratio is related to changes in redox conditions at the lake floor. The oxygen availability in the lake floor depends on the duration of the ice cover during winter. Strengthened Siberian High (SH) causes colder autumn and winter temperatures and therefore leads to extended duration of ice cover. Fe/Mn can be considered as a proxy for SH. The sediment record suggests pronounced, generally positive but strongly fluctuating NAO phase, from ca. 4100 to 3200 varve yr BP. Periods of strengthened SH are observed at 3900–3600, 1900–1500, and 1200–750 varve yr BP. Our study suggests that NAO and SH operate individually, are not clearly linked, and do not entirely block each other.

Description: Dissolution of rocks such as anhydrite, gypsum, limestone, dolomite or salt rock enlarges fractures or pore space and finally results in voids and cavities within karst rocks. Especially in populated areas such collapses may have catastrophic consequences, but the current knowledge about the evolution, governing processes and capabilities of prediction are insufficient. Geophysical methods can contribute to the understanding, first of all by detailed investigation of known sinkhole structures and - later on - by monitoring areas of high risk as well as localising those areas before a surface expression is visible. As voids and cavities are often fluid- or air-filled (or both) and the electrical properties of the fluid and air are in many cases significantly different to those of the surrounding karst rocks, electric and electromagnetic methods such as, e.g., electrical resistivity tomography (ERT), ground-penetrating radar (GPR) and nuclear magnetic resonance (NMR) are potentially useful tools for the investigation of sinkhole structures. In the case study presented here we focus on the application of electric and electromagnetic methods on the karst system of the Innerste Mulde in Lower Saxony which is surface-mapped by numerous sinkhole structures.

Description: The aim of TERENO (TERrestrial ENvironmental Observatories) is to collect long-term observation data on the hydrosphere, biosphere, pedosphere, lower atmosphere and anthroposphere along multiple spatial and temporal gradients in climate sensitive regions across Germany. The lysimeter-network SOILCan was installed as a part of TERENO between March and December 2010 within the four observatories. It represents a long-term large-scale experiment to study the effects of climate and management changes in terrestrial ecosystems, with particular focus on the impact of these changes on water, energy and matter fluxes into groundwater and atmosphere. SOILCan primarily focuses on soil hydrology, the carbon and nutrient cycle and plant species diversity. Time series measurements of states and fluxes at high spatial and temporal resolution in the soil and biosphere are combined with remote sensing information for the development and calibration of process-based models simulating impacts of climate change in soil processes at field to regional scale. Within the framework of SOILCan, 132 fully automated lysimeter systems were installed at 14 highly equipped experimental field sites across the four TERENO observatories. Relevant state variables of grassland and arable ecosystems are monitored characterizing climate, hydrology and matter fluxes into the atmosphere and within the hydrosphere as well as plant species diversity. Lysimeters are either being operated at or near their original sampling location or were transferred within or between the four TERENO observatories thereby using temperature and rainfall gradients to mimic future climatic conditions (space for time), which allow measuring impacts of climate change on terrestrial ecosystems. The lysimeters are cultivated as grassland (intensive, extensive and non-used) or arable land, the latter with a standardized crop rotation of winter wheat—winter barley—winter rye—oat. This publication describes the general design of the SOILCan experiment including a comprehensive description of the pedological characteristics of the different sites and presents a few exemplary results from the first years of operation.

Description: This thesis addresses the complexity in the patterns of deformation in accretionary wedges based on analogue modelling. A combined approach of 1) statistically assessing results from sand wedges 2) mechanically analyzing fault behavior in the structural evolution of sand wedge and 3) comparing varying wedge geometry and dynamics to theory, are used in an effort to unravel the complexity that develops as the wedge evolves. This thesis comprises of three manuscripts addressing these three approaches respectively. The experimental database is derived from analysis of 27 analogue sand wedge models where the friction of the basal décollement is varied. The kinematics of the analogue sand wedge is monitored using Particle Image Velocimetry (PIV) that provides detailed information on the displacements in the wedge. The statistical approach (Chi square test, ANOVA test) consists of quantifying the degree of both intrinsic variations in the results of the model and extrinsic variation caused by the varying basal friction. In particular the statistical study shows that intrinsic variability of fault and wedge observables is related to the mechanics and material properties of the wedge. In addition, results show that analogue experiments are reproducible. The next study presented in this thesis reflects on the faults of the wedge. Fault activity, in particular fault formation, reactivation and underthrusting are described. The observations are explained mechanically in relation to the fault geometry and the changing frictional properties along the fault plane. It is also demonstrated that fault activity governs the shape, activity and eventual zonation of the wedge. Additionally, a comparison between two theories 1) Critical taper theory and the 2) Minimum work theory is performed to recognize which theory best represents the deformation in accretionary wedges. The critical taper theory focuses on the geometry of the wedge and the minimum work theory focuses on the energy in the wedge. It is evident that both theories are applicable, however at different stages of an accretionary cycle. Overall, the minimum work theory determines the path of deformation needed to reach that geometry determined by the critical taper theory. Research to explore the role of ductile behavior in the wedge is also initiated. Preliminary stages of the research include the characterization of a new elasto-plastic viscous material called Carbopol that behaves in a viscous manner after a certain yield strength is overcome i.e. Herschel Bulkley fluid. A rheological study tests the effect of concentration of three different types of commercial Carbopol products. Besides this research, the monitoring of forces in analogue models is also attempted with a new setup. The combination of high resolution force recordings and visual PIV data provides an insightful view into the dynamics of the model.

Description: In this review paper we summarise a series of numerical abrupt climate change experiments in the context deglaciation. The effects of global warming, deglacial freshwater, and ice sheets for the termination of the last ice age are examined in a model of intermediate complexity and a fully coupled, coarse-resolution climate model. We find that gradual deglacial global warming induces an abrupt strengthening of the Atlantic Meridional Overturning Circulation (AMOC). More generally, if the system is in a bistable window, a linear forcing can yield non-linear AMOC changes. In this sense Northern Hemisphere freshwater hosing only modulates the timing of the AMOC onset. Furthermore, Northern Hemisphere freshwater hosing weakens the AMOC with a potential overshoot, after the freshwater forcing has stopped. Therefore, as a further hypothesis the onset of Bølling/Allerød (B/A) interstadial with warming over Greenland could be related to an increase in AMOC, which is induced by a declining freshwater forcing prior to or in parallel with the transition. In contrast, hosing in the Southern Hemisphere has a relatively minor influence on the AMOC. The associated climate signatures and mechanisms are explored and discussed in this study.

Description: In diesem Übersichtsbeitrag stellen wir eine Reihe von numerischen Experimenten zum abrupten Klimawandel am Ende der letzten Eiszeit vor. Die Auswirkungen der globalen Erwärmung, des deglazialen Süßwassers und der Eisschilde auf die Termination und Ozeanzirkulation werden in einem Modell mittlerer Komplexität und einem vollständig gekoppelten Klimamodell untersucht. Unsere Modellergebnisse vermitteln Einsichten in die abrupte Erwärmung in der Nordhemisphäre, das sogenannte Bølling/Allerød (B/A) Nordatlantik Interstadial, und der deglazialen Schmelzwasserpulse. Wir stellen fest, dass die deglaziale globale Erwärmung eine Verstärkung der atlantische Umwälzbewegung (Atlantic Meridional Overturning Circulation, AMOC) induziert. Wenn sich das System in einem bistabilen Fenster bewegt, kann ein linearer Antrieb zu einer nichtlinearen Antwort in der AMOC führen, wobei das Schmelzwasser den Zeitpunkt für das B/A verändern kann und die AMOC schwächt. Bei der Rückkehr in den Usprungszustand kann die AMOC überschwingen, d.h. sie zeigt stärkere Amplituden als unter ungestörten Bedingungen. Deglaziales Süßwasser in der südlichen Hemisphäre hat einen relativ kleinen Effekt auf die AMOC. Als weitere, alternative Hypothese zum Vorhandensein des B/A-Interstadials könnte auch die Abwesenheit von Süßwasser beigetragen haben. Dadurch wird die AMOC verstärkt und infolgedessen Grönland erwärmt. Signaturen und Mechanismen dieser Prozesse werden in diesem Beitrag untersucht und diskutiert.