ALBERT

Beschreibung: The role of aerial dispersal in shaping patterns of biodiversity remains poorly understood, mainly due to a lack of coordinated efforts in gathering data at appropriate temporal and spatial scales. It has been long known that the rate of dispersal to an ecosystem can significantly influence ecosystem dynamics, and that aerial transport has been identified as an important source of biological input to remote locations. With the considerable effort devoted in recent decades to understanding atmospheric circulation in the south-polar region, a unique opportunity has emerged to investigate the atmospheric ecology of Antarctica, from regional to continental scales. This concept note identifies key questions in Antarctic microbial biogeography and the need for standardized sampling and analysis protocols to address such questions. A consortium of polar aerobiologists is established to bring together researchers with a common interest in the airborne dispersion of microbes and other propagules in the Antarctic, with opportunities for comparative studies in the Arctic.

Beschreibung: We compute displacements of global SLR station coordinates by atmospheric loading based on surface pressure data from European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-interim data. Inhouse we generate two branches: firstly straightforward following Farrel’s theory but using updated load Love numbers, secondly from utilizing localized Green’s functions instead of global ones. Externally provided displacements are available f.i. from the International Mass Loading Service (IMLS) based on different input data and modeling. We compare these displacements and apply them to Satellite Laser Ranging (SLR) data processing of a recent six years period of the LAGEOS, LARES, AJISAI, STARLETTE and STELLA geodetic missions. We assess the impact of the loading models on precise orbit determination and Earth parameters of interest.

Beschreibung: Triples of GPS radio occultation (RO) temperature data are used to derive horizontal and vertical gravity wave (GW) parameters in the stratosphere between 20 km and 40 km from which the vertical flux of horizontal momentum is determined. Compared to previous studies using RO data, better limiting values for the sampling distance (Δd≤250 km) and the time interval (Δt≤15 min) are used. For several latitude bands the mean momentum fluxes (MFs) derived in this study are considerably larger than MF from other satellite missions based on horizontal wavelengths calculated between two adjacent temperature profiles along the satellite track. Error sources for the estimation of MF from RO data and the geometrical setup for the applied method are investigated. Another crucial issue discussed in this paper is the influence of different background separation methods to the final MF. For GW analysis a measured temperature profile is divided into a fluctuation and a background and it is assumed that the fluctuation is caused by GWs only. For the background separation, i.e., the detrending of large-scale processes from the measured temperature profile, several methods exist. In this study we compare different detrending approaches and for the first time an attempt is made to detrend RO data with ERA-Interim data from the European Centre for Medium-Range Weather Forecasts. We demonstrate that the horizontal detrending based on RO data and ERA-Interim gives more consistent results compared with a vertical detrending.

Beschreibung: Remote sensing observations and rover missions have documented the presence of sulphate-rich mineral associations on Mars. Many of these minerals are paleo-indicators of hydrous, acidic and oxidising environments that must have prevailed in Mars´ distant past, contrary to the present conditions. Furthermore, occurrences of silica together with high Cl and Br concentrations in Martian soils and rocks represent fingerprints of chemically atypical fluids involved in processes operating on the surface or at shallow depth. From field observations at representative active volcanoes in subduction settings, supported by geochemical modelling, we demonstrate that volcanic hydrothermal systems are capable of producing Mars-like secondary mineral assemblages near lakes, springs and fumaroles through the action of acidic fluids. Water–gas-rock interactions, together with localised flow paths of water and fumarolic gas emitted from associated subaerial vents, lead to deposition of a range of sulphates, including gypsum, jarosite, alunite, epsomite and silica. Evaporation, vapour separation and fluid mixing in (near-) surface environments with strong gradients in temperature and fluid chemistry further promote the diversity of secondary minerals. The mineralogical and chemical marks are highly variable in space and time, being subject to fluctuations in ambient conditions as well as to changes in the status of volcanic-hydrothermal activity. It is concluded that active processes in modern volcanic-geothermal systems may be akin to those that created several of the sulphate-rich terrains in the early history of Mars.

Beschreibung: Permafrost regions are highly sensitive to climate change. Bringing research data and metadata from diverse sources together and visualising them within a publicly available worldwide system would have an enormous impact on data accessibility and availability and would significantly promote scientific work. The CarboPerm WebGIS, a case study focusing on the Lena River Delta in the Laptev Sea Region (Siberia), shows how a WebGIS infrastructure can support scientific work, data management, data visualisation, and data publication. CarboPerm is an interdisciplinary German project with Russian cooperation, investigating the formation, turnover and release of carbon in Siberian permafrost landscapes. There, the Lena River formed the largest delta in the Arctic and is place of long-term Russian-German scientific cooperation in permafrost research. The CarboPerm WebGIS is being set up to visualise and emphasise the spatial context of local samples, measurements, and analyses versus the thematic background information (e.g., geomorphology, pedology, geology and vegetation), using the WebGIS infrastructure “maps@awi” at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). The CarboPerm WebGIS database includes historical data from long-term Russian-German cooperation and recent field campaigns as well as environmental datasets that are freely available via the internet or research data repositories.

Beschreibung: Permafrost-Landschaften reagieren sehr sensibel auf den Klimawandel. Die Synthese von Forschungsdaten und Metadaten über diese Gebiete und deren Visualisierung in einem interoperablen, weltweit zugänglichen System ist von hohem Nutzen für Wissenschaft und Gesellschaft. Innerhalb des Permafrost-Forschungsprojektes CarboPerm wird für das Lena- Delta und die Laptevmeer-Region ein WebGIS-Projekt entwickelt, welches die wissenschaftliche Forschertätigkeit durch Datenmanagement, Datenvisualisierung und Datenpublikation unterstützt. CarboPerm ist ein interdisziplinäres deutsch-russisches Kooperationsprojekt, das die Bildung, den Umsatz und die Freisetzung von Kohlenstoff in sibirischen Permafrost-Landschaften untersucht. Der Fluss Lena hat das größte Delta in der Arktis ausgebildet und ist gleichzeitig ein Kerngebiet langjähriger russisch-deutscher Kooperation in der Permafrost-Forschung. Das CarboPerm WebGIS wurde ins Leben gerufen, um den räumlichen Bezug von lokalen Probennahmen, Messergebnissen und Analysen mit thematischen Hintergrundinformationen, wie z.B. Geomorphologie, Pedologie, Geologie und Vegetation zu visualisieren. Die CarboPerm-WebGIS-Datenbank entstand unter Nutzung der WebGIS-Infrastruktur „maps@awi“ am Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI). Sie beinhaltet sowohl historische Daten aus der langjährigen russisch-deutschen Kooperation als auch von aktuellen Geländekampagnen, sowie umweltrelevante räumliche Datensätze, die aus öffentlich zugänglichen Datenquellen und Daten-Repositorien stammen.

Beschreibung: Our knowledge of the origin of Love waves in the ambient seismic noise is extremely limited. This applies in particular to constraints on source locations and source mechanisms for Love waves in the secondary microseism. Here three‐component beamforming is used to distinguish between the differently polarized wave types in the primary and secondary microseismic noise fields, recorded at several arrays across Europe. We compare characteristics of Love and Rayleigh wave noise, such as source directions and frequency content, measure Love to Rayleigh wave ratios for different back azimuths, and look at the seasonal behavior of our measurements by using a full year of data in 2013. The beamforming results confirm previous observations that back azimuths for Rayleigh and Love waves in both microseismic bands mainly coincide. However, we observe differences in relative directional noise strength between both wave types for the primary microseism. At those frequencies, Love waves dominate on average, with kinetic Love‐to‐Rayleigh energy ratios ranging from 0.6 to 2.0. In the secondary microseism, the ratios are lower, between 0.4 and 1.2. The wave type ratio is directionally homogeneous, except for locations far from the coast. In the primary microseism, our results support the existence of different generation mechanisms. The contribution of a shear traction‐type source mechanism is likely.

Beschreibung: We report the first findings of coexisting early Holocene Hässeldalen and Askja-S cryptotephras in a varved sediment record in Lake Czechowskie (Poland). A time span of 152 +11/−8 varve years between the two tephras has been revealed by differential dating through varve counting. This is in agreement within the uncertainties with calculations from radiocarbon-based age models from the non-varved Hässeldala port record in southern Sweden, but shorter than assumed from the non-varved lake record on the Faroe Islands. We discuss possible reasons for the observed differences in duration between the two tephras and provide a revised absolute age for the Askja-S tephra of 11 228 ± 226 cal a BP based on anchoring our floating varve chronology to the absolute timescale by using the Hässeldalen Tephra as dated in the Hässeldala port sediments (11 380 ± 216 cal a BP). This age agrees with radiocarbon age models with larger uncertainty ranges, but is slightly older than radiocarbon-based age models with narrow uncertainty bands and is even 200–300 years older than the age reported from the Faroe Islands record. In addition to these chronological issues we discuss the possible response of the Czechowskie sediment record to the Preboreal climate oscillation.

Beschreibung: The application of thermo-sensitive tracers is a promising technique for evaluating the thermal state of geothermal reservoirs. To extend the compound spectrum for hydrolyzable compounds to reservoir temperatures between 100 and 200 °C carboxamides were studied. The kinetic parameters of 17 self-synthesized amides were determined in hydrothermal batch and autoclave experiments. The influence of the molecular structure and the role of pH/pOH on hydrolysis kinetics were studied. Additionally, the thermal stabilities of the hydrolysis products were evaluated. The results demonstrate the high potential of tracers based on amide hydrolysis for use in medium enthalpy reservoirs.

Beschreibung: In der Geoelektromagnetik werden oft großflächige Quellen, beispielsweise Leiterschleifen, näherungsweise als Punktquellen aufgefasst. Diese Annahme ist jedoch nur für hinreichend große Entfernungen zwischen Quelle und Messpunkt zulässig. Da die Messung mit relativ kleinen Spulen durchgeführt werden, die Sendespulen aber bis zu 10 000m2 Spulenfläche aufweisen, liegt es nahe, das Reziprozitätsprinzip auszunutzen, um Sender und Empfänger zu vertauschen. So wird das Feld eines Sendedipols am Ort des eigentlichen Empfängers genutzt, um über die Lösung dieses Dipols am Ort des eigentlichen Senders zu integrieren. Die Integrationsfläche entspricht dabei der Fläche der eigentlichen Sendeschleife. Dabei kann die Lösung des Dipols entweder analytisch über homogenen oder geschichteten Leitfähigkeitsmodellen oder numerisch über beliebigen Leitfähigkeitsverteilungen berechnet werden. Um den Einfluss der Spulengeometrie abzuschätzen, gen¨ugt meist die Auswertung der analytischen L¨osung. Die numerische Integration geschieht dabei durch eine zweidimensionale Gaußquadratur. Eine Konvergenzstudie zeigt die Abhängigkeit der Genauigkeit dieses Ansatzes von der Knotenzahl der Gaußquadratur in Verbindung mit ausgew¨ahlten Entfernungen zwischen Senderzentrum und Messpunkt.

Beschreibung: Madagascar occupies a key position in the assembly and breakup of the supercontinent Gondwana. It has been used in numerous geological studies to reconstruct its original position within Gondwana and to derive plate kinematics. Seismological observations in Madagascar to date have been sparse. Using a temporary, dense seismic profile across southern Madagascar, we present the first published study of seismic anisotropy from shear wave splitting analyses of teleseismic phases. The splitting parameters obtained show significant small-scale variation of fast polarization directions and delay times across the profile, with fast polarization rotating from NW in the center to NE in the east and west of the profile. The delay times range between 0.4 and 1.5 s. A joint inversion of waveforms at each station is applied to derive hypothetical one-layer splitting parameters. We use finite-difference, full-waveform modeling to test several hypotheses about the origin and extent of seismic anisotropy. Our observations can be explained by asthenospheric anisotropy with a fast polarization direction of 50°, approximately parallel to the absolute plate motion direction, in combination with blocks of crustal anisotropy. Predictions of seismic anisotropy as inferred from global mantle flow models or global anisotropic surface wave tomography are not in agreement with the observations. Small-scale variations of splitting parameters require significant crustal anisotropy. Considering the complex geology of Madagascar, we interpret the change in fast-axis directions as a ~150 km wide zone of ductile deformation in the crust as a result of the intense reworking of lithospheric material during the Pan-African orogeny. This fossil anisotropic pattern is underlain by asthenospheric anisotropy induced by plate motion.

Beschreibung: In the present paper we describe the on-land field operations integrated in the TOMO-ETNA experiment carried out in June-November 2014 at Mt. Etna volcano and surrounding areas. This terrestrial campaign consists in the deployment of 90 short-period portable three-component seismic stations, 17 Broadband seismometers and the coordination with 133 permanent seismic station belonging to Italy’s Istituto Nazionale di Geofisica e Vulcanologia (INGV). This temporary seismic network recorded active and passive seismic sources. Active seismic sources were generated by an array of air-guns mounted in the Spanish oceanographic vessel “Sarmiento de Gamboa” with a power capacity of up to 5200 cubic inches. In total more than 26,000 shots were fired and more than 450 local and regional earthquakes were recorded. We describe the whole technical procedure followed to guarantee the success of this complex seismic experiment. We started with the description of the location of the potential safety places to deploy the portable network and the products derived from this search (a large document including full characterization of the sites, owners and indication of how to arrive to them). A full technical description of the seismometers and seismic sources is presented. We show how the portable seismic network was deployed, maintained and recovered in different stages. The large international collaboration of this experiment is reflected in the participation of more than 75 researchers, technicians and students from different institutions and countries in the on-land activities. The main objectives of the experiment were achieved with great success.

Beschreibung: Ground motion intensity measures such as the peak ground acceleration (PGA) and the pseudo-spectral acceleration (PSA) at two sites due to the same seismic event are correlated. The spatial correlation needs to be considered when modeling ground-motion fields for seismic loss assessments, since it can have a significant influence on the statistical moments and probability distribution of aggregated seismic loss of a building portfolio. Empirical models of spatial correlation of ground motion intensity measures exist only for a few seismic regions in the world such as Japan, Taiwan and California, since for this purpose a dense observation network of earthquake ground motion is required. The Istanbul Earthquake Rapid Response and Early Warning System (IERREWS) provides one such dense array with station spacing of typically 2 km in the urban area of Istanbul. Based on the records of eight small to moderate (Mw3.5–Mw5.1) events, which occurred since 2003 in the Marmara region, we establish a model of intra-event spatial correlation for PGA and PSA up to the natural period of 1.0 s. The results indicate that the correlation coefficients of PGA and short-period PSA decay rapidly with increasing interstation distance, resulting in correlation lengths of approximately 3–4 km, while correlation lengths at longer natural periods (above 0.5 s) exceed 6 km. Finally, we implement the correlation model in a Monte Carlo simulation to evaluate economic loss in Istanbul's district Zeytinburnu due to a Mw7.2 scenario earthquake.

Beschreibung: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy. IGETS continues the activities of the Global Geodynamics Project (GGP) between 1997 and 2015 to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. As a new addition to this network, the iGrav-027 superconducting gravimeter had been installed at the Borowa Gora Geodetic-Geophysical Observatory which has been established in late 1930s. Continuous time-varying gravity and atmospheric pressure data from the SGs at Borowa Gora are integrated in the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. Borowa Gora Geodetic-Geophysical Observatory is located in Poland, situated 50 km north of Warsaw (longitude: 21.0359 E, latitude: 52.2755 N, height above MSL: 109 m). The operation and maintenance of the Borowa Gora instrumentation is done by staff of the Institute of Geodesy and Cartography. The shortest distance to the Baltic Sea coastline is approx. 240 km. The area is located in a tectonically quiet zone. Geologically the situation is not well recognized, a significant size artificial reservoir is located within 1-2 km from the Observatory. The environment is a not significantly urbanized area with visible daily seismicity. The climate at this place has rough winters (up to -20 degrees Celsius) and hot summers (up to 35 degrees Celsius). The iGrav-027 is located in a specially prepared chamber in the basement of one of the Observatory buildings. It is separated from the compressor operating in a separate room. The location of the gravimeter ensures a relatively stable temperature of 21°C ±2°C throughout the year. The instrument is placed on a specially prepared concrete monument of 1.2 × 1.2 m horizontal and 1.5 m vertical dimensions (ca 1.3 m deep below floor level). The sensor of the instrument is located about 2 m below ground level, and the position and height of the instrument has been determined with a centimetre accuracy, before the installation. The iGrav-027 is co-located in the same building with the A10-020 absolute gravimeter. There are three well monumented pillars for absolute gravity determinations, which can be conducted along with the operating iGrav-027 (e.g. for the comparison with absolute gravimeters). In the vicinity of the observatory several further pillars were set up for various other geodetic antennas and instrumentation. Borowa Gora is a geodynamic observatory comprising space techniques and ground instruments. The iGrav-027 operation started at the end of April 2016, official start is assigned as from 1th of May 2016. Since that time the time series is carried out without interruption up to present. The time sampling of the raw gravity and barometric pressure data of IGETS Level 1 is 1 minute. Future plans include uploading 1s data sampling also. In addition, Borowa Gora is equipped with auxiliary data supporting the interpretation of the SG measurements, which is, however, not provided in the IGETS data base due to complexity. These are a local network of hydrological and meteorological sensors as well as two permanent GNSS (Global Navigation Satellite Systems) stations BOGO and BOGI. Additionally magnetic field variations are also recorded.

Beschreibung: To investigate temporal seismic velocity changes due to earthquake related processes and environmental forcing in Northern Chile, we analyse 8 yr of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC). By autocorrelating the ambient seismic noise field measured on the vertical components, approximations of the Green’s functions are retrieved and velocity changes are measured with CodaWave Interferometry. At station PATCX, we observe seasonal changes in seismic velocity caused by thermal stress as well as transient velocity reductions in the frequency range of 4–6 Hz. Sudden velocity drops occur at the time of mostly earthquake-induced ground shaking and recover over a variable period of time. We present an empirical model that describes 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. We show that the shaking effect is accumulated over time and best described by the integrated envelope of the ground acceleration over the discretization interval of the velocity measurements, which is one day. In our model, the amplitude of the velocity reduction as well as the recovery time are proportional to the size of the excitation. This model with two free scaling parameters 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 our measurement period. A clear relationship between ground shaking and induced velocity reductions is not visible at other stations. We attribute the outstanding sensitivity of PATCX to ground shaking and thermal stress to the special geological setting of the station, where the subsurface material consists of relatively loose conglomerate with high pore volume leading to a stronger nonlinearity compared to the other IPOC stations.

Beschreibung: Vorliegender Datensatz gibt auf Basis einer Analyse im Dezember 2015 im re3data.org - Registry of Research Data Repositories1 einen Überblick über Forschungsdaten-Repositorien die unter Beteiligung deutscher Institutionen betrieben werden.

Beschreibung: We use the recorded seismicity, confined to the Dead Sea basin and its boundaries, by the Dead Sea Integrated Research (DESIRE) portable seismic network and the Israel and Jordan permanent seismic networks for studying the mechanisms of earthquakes in the Dead Sea basin. The observed seismicity in the Dead Sea basin is divided into nine regions according to the spatial distribution of the earthquakes and the known tectonic features. The large number of recording stations and the adequate station distribution allowed the reliable determinations of 494 earthquake focal mechanisms. For each region, based on the inversion of the observed polarities of the earthquakes, we determine the focal mechanisms and the associated stress tensor. For 159 earthquakes, out of the 494 focal mechanisms, we could determine compatible fault planes. On the eastern side, the focal mechanisms are mainly strike-slip mechanism with nodal planes in the N-S and E-W directions. The azimuths of the stress axes are well constrained presenting minimal variability in the inversion of the data, which is in agreement with the Eastern Boundary fault on the east side of the Dead Sea basin and what we had expected from the regional geodynamics. However, larger variabilities of the azimuthal and dip angles are observed on the western side of the basin. Due to the wider range of azimuths of the fault planes, we observe the switching of σ1 and σ2 or the switching of σ2 and σ3 as major horizontal stress directions. This observed switching of stress axes allows having dip-slip and normal mechanisms in a region that is dominated by strike-slip motion.

Beschreibung: We estimated the shear-wave velocity structure and Vp/Vs ratio of the crust beneath the Sumatra region by inverting stacked receiver functions from five three-component broadband seismic stations, located in diverse geologic setting, using a well known non-linear direct search approach, Neighborhood Algorithm (NA). Inversion results show significant variation of sediment layer thicknesses from 1 km beneath the backarc basin (station BKNI and PMBI) to 3–7 km beneath the coastal part of Sumatra region (station LHMI and MNAI) and Nias island (station GSI). Average sediment layer shear velocity (Vss) beneath all the stations is observed to be less (∼1.35 km/s) and their corresponding Vp/Vs ratio is very high (∼2.2–3.0). Crustal thickness beneath Sumatra region varies between 27 and 35 km, with exception of 19 km beneath Nias island, with average crustal Vs ∼3.1–3.4 km/s (Vp/Vs ∼1.8). It is well known that thick sediments with low Vs (and high Vp/Vs) amplify seismic waves even from a small-magnitude earthquake, which can cause huge damage in the zone. This study can provide the useful information of the crust for the Sumatra region. Since, Sumatra is an earthquake prone zone, which suffered the strong shaking of Great Andaman–Sumatra earthquake; this study can also be helpful for seismic hazard assessment.

Beschreibung: Als Voruntersuchung für das Forschungsprojekt DESMEX (Deep Electromagnetic Sounding for Mineral Exploration) werden ein -/ und zweidimensionale Modellierungen von LOTEM Daten durchgeführt. Mittels 1D Modellierung kann die optimale Sender-Empfänger Geometrie und die maximal benötigte Aufzeichnungszeit festgelegt werden, um eine gutleitfähige Schicht in einer Tiefe von ca. 1 km detektieren zu können. Mit der anschließenden 2D Modellierung wird die gutleitfähige Schicht als nicht durchgehend und verschiedene Neigungen der Schicht angenommen. Durch den Vergleich der synthetischen 2D Daten mit den synthetischen 1D Daten für verschiedene Sender-Empfänger Lokationen entlang des Profils, kann der 2D Effekt abgeschätzt werden. Mit einer abschließenden 1D Inversion können Aussagen über die Angemessenheit einer 1D Inversion von 2D beeinflussten Daten getroffen werden und mögliche Fehlinterpretationen eingeschätzt werden.

Beschreibung: „Der Schutz des Grundwassers als Daseinsfürsorge ist wichtig und richtig. Die energetische Nutzung des Untergrunds, auch des Grundwassers und der Grundwasserleiter hat ebenfalls ihre Berechtigung und wird zukünftig immer wichtiger werden“ (Scheytt und Massmann 2016). Die Quintessenz des Editorials des vorherigen Heftes gilt unverändert auch für diese Ausgabe. Wir möchten hier Beispiele für Chancen geben, die der geologische Untergrund für die Energiewende bietet, aber gleichzeitig auch damit verbundene Risiken aufzeigen. Ausgangsbasis ist das Energiekonzept der Bundesregierung für eine umweltschonende, zuverlässige und bezahlbare Energieversorgung. Darin festgelegt ist eine Reduktion der Treibhausgasemissionen bis zum Jahr 2050 um 80–95 %, bezogen auf den Ausstoß von 1990. Im gleichen Zeitraum soll der Anteil der regenerativen Energien am Bruttoenergieverbrauch in Deutschland auf 60 % erhöht werden. Folgt man dem Modell des Fraunhofer-Instituts für Solare Energiesysteme (Henning und Palzer 2014), dann ist für Deutschland eine Energieversorgung mit Strom und Wärme zu 100 % über regenerative Energie möglich. In den quantitativen Modellen werden ausschließlich bereits verfügbare Technologien innerhalb ihrer bekannten Potenzialgrenzen betrachtet. Aufgrund der Nichtplanbarkeit der Energieerzeugung aus Sonne und Wind werden Speicher wie Pumpspeicher-Kraftwerke, Batterien, Wärme- und Methangasspeicher berücksichtigt. Zudem ist oberflächennahe Geothermie über elektrische Wärmepumpen in das System integriert. Das theoretische geothermische Potenzial Deutschlands errechnet sich aus der Wärmemenge, die in prinzipiell erbohrbarer Tiefe gespeichert ist. Diese Wärmemenge entspricht etwa 3‑mal dem aktuellen weltweiten und 115-mal dem deutschen Verbrauch. Dieses theoretische Potenzial ist jedoch aufgrund einer Vielzahl von Restriktionen nicht erschließbar. Beispielsweise sind Flächen, die von potenziellen Verbrauchern weit entfernt liegen, wegen zu hoher Verluste beim Energietransport für eine Erdwärmenutzung ungeeignet. Nachhaltig für Deutschland wäre Geothermie, wenn nur der permanente natürliche Wärmestrom, der sich oberflächennah durch Sonneneinstrahlung sowie dem Wärmestrom aus dem Erdinneren ergibt, genutzt würde. Diese Leistung lässt sich erhöhen, wenn neben der Wärmenutzung im Winter auch im Sommer durch Gebäudekühlung im Überschuss vorhandene Wärme in den Untergrund zurückgespeichert wird. Untergrundgasspeicherung ist Stand der Technik. Die aktuelle Kapazität aller Untergrundgasspeicher in Deutschland liegt bei 24 Milliarden Norm-Kubikmetern Methangas. Diese Menge entspricht 3‑mal jener im Modell des Fraunhofer-Instituts zugrunde gelegten zu speichernden Energie. Untertagegasspeicher sind zudem eine Option als bevorratendes Bindeglied bei der Speicherung von Strom aus regenerativen Energien. Wesentliche Grundlage dabei ist das „Power to Gas“-Verfahren. Überschussenergie lässt sich über Wasserstoff zusammen mit Kohlenstoffdioxid in Methan (synthetisches Erdgas) umwandeln, welches man bei Bedarf nutzen kann. Für Deutschland ergibt sich eine Kapazität für die Technologie basierend auf der aktuellen Anzahl bereits vorhandener Gasspeicher von 20–60 % der 90–270 TWh Überschussenergie, die für das Jahr 2050 erwartet werden (Kühn et al. 2013). Ein Risiko, das man bei der Nutzung des unterirdischen Raums eingeht, ist die induzierte Seismizität. Die stärksten Beben, die in Deutschland bislang aufgezeichnet wurden, sind natürliche, geologische Ereignisse im Bereich MW 6–7. Der Mensch spürt Magnituden kleiner 3 generell nicht. Bei der Erdgasförderung, beim Kohle- und Erzbergbau sowie durch den Betrieb von Staudämmen lagen die Messungen maximal im Bereich MW 4–5, beim Salzbergbau bei maximal MW 5–6. Im Rahmen geothermischer Erkundung oder Nutzung des Untergrundes lagen die Beben bislang immer unterhalb von MW 4 (Grünthal 2014). Bohrungen sind potenzielle Leckagewege, weil durch sie Wegsamkeiten im Untergrund hergestellt werden. Es gibt industrielle Erfahrungen aus mehr als 4 Millionen Öl- und Gas-Bohrungen rund um die Welt. Einerseits kann jede Bohrung theoretisch versagen und Leckagen verursachen, andererseits aber durch Reparaturmaßnahmen auch wiederhergestellt werden. Von den 4 Millionen Bohrungen sind 25 Dokumentationen von insgesamt 400.000 zugänglich. Darin wird je nach Nutzung in 1,9–75 % der Fälle ein Versagen der Zementierung oder der Verrohrung berichtet (Davies et al. 2014). Der geologische Untergrund liefert in signifikanter Größenordnung einerseits Trinkwasser und die klassischen Rohstoffe Erdöl und Erdgas. Andererseits steht Speicherplatz für Gas, Wärme und Kälte zur Verfügung (Martens und Kühn 2015). Unsere Aufgabe als Geowissenschaftler und Ingenieure ist es, die Antwort auf die Frage zu geben, wie die Georessourcen und der Untergrund verantwortungsvoll und nachhaltig genutzt und zur Realisierung der Ziele im Rahmen der Umsetzung der Energiewende herangezogen werden können.

Beschreibung: Geophysical monitoring activities were an important component of the CO2 injection program at the Ketzin site, Germany. Here we report on the seismic and electrical resistivity tomography (ERT) measurements performed during the period of the site development and CO2 injection. Details on the site geology, the history of the CO2 injection operation, and petrophysical models relevant for the interpretation of the geophysical data are presented. The seismic measurements comprise 2D and 3D surface seismic surveys, vertical seismic profilings, and crosshole measurements. Apart from the measurements, results from advanced processing methods, such as impedance inversion and full-waveform inversion are also presented. In addition, results from crosshole ERT and surface-downhole ERT are presented. If operational efforts are taken into consideration we conclude that a combination of several geophysical methods is preferable given the demands of a spatiotemporally comprehensive monitoring program. We base this conclusion on that the different imaging characteristics and petrophysical sensitivities of different methods can complement each other. An important finding is, based on signal quality and reduced operational costs, that the use of permanent installations is promising. Generally, specific monitoring layouts will depend on site-specific characteristics, such as reservoir depth, availability of wells, petrophysical characteristics, and accessibility of surface locations. Given the comprehensive range of methods applied, the reported results are not only relevant to the operation of CO2 storage sites, but are also of interest to other monitoring projects dealing with fluid injection or production.

Beschreibung: The 2015 Mw8.3 Illapel, Chile earthquake is the latest megathrust event on the central segment of that subduction zone. It generated strong ground motions and a large (up to 11 m runup) tsunami which prompted the evacuation of more than 1 million people in the first hours following the event. Observations during recent earthquakes suggest that these phenomena can be associated with rupture on different parts of the megathrust. The deep portion generates strong shaking while slow, large slip on the shallow fault is responsible for the tsunami. It is unclear whether all megathrusts can have shallow slip during coseismic rupture and what physical properties regulate this. Here we show that the Illapel event ruptured both deep and shallow segments with substantial slip. We resolve a kinematic slip model using regional geophysical observations and analyze it jointly with teleseismic backprojection. We find that the shallow and deep portions of the megathrust are segmented and have fundamentally different behavior. We forward calculate local tsunami propagation from the resolved slip and find good agreement with field measurements, independently validating the slip model. These results show that the central portion of the Chilean subduction zone has accumulated a significant shallow slip deficit and indicates that, given enough time, shallow slip might be possible everywhere along the subduction zone.

Beschreibung: Die vorliegende Ausgabe des GFZ-Journals „System Erde“ soll einen Einblick in die am GFZ betriebene Forschung zur Seismologie geben.

Beschreibung: Shallow groundwater resources could be possibly affected by intruding brines, which are displaced along hydraulically conductive faults as result of subsurface activities like CO2 injection. To avoid salinization of potable freshwater aquifers an early detection of intruding saline water is necessary, especially in regions where an initial geogenic salinization already exists. Our study is based on work of Tillner et al. [1] and Langer et al. [2] who investigated the influence of permeable fault systems on brine displacement for the prospective storage site Beeskow-Birkholz in the Northeast German Basin. With a 3D regional scale model considering the deep groundwater system, they demonstrated that the existence of hydraulically conductive faults is not necessarily an exclusion criterion for potential injection sites, because salinization of shallower aquifers strongly depends on the effective damage zone volume, the initial salinity distribution and overlying reservoirs [2], while permeability of fault zones does not influence salinization of shallower aquifers significantly [1]. Here we extracted a 2D cross section regarding the upper 220 m of the study area mainly represented by shallow freshwater aquifers, but also considering an initial geogenic salinization [3]. We took flow rates of the intruding brines from the previous studies [2] and implemented species transport simulations with the program code SHEMAT [4]. Results are investigated and interpreted with the hydrochemical genesis model GEBAH [5] which has been already applied as early warning of saltwater intrusions into freshwater aquifers and surface water [6]. GEBAH allows a categorization of groundwater by the ion ratios of the dissolved components and offers a first indicative determination for an existence and the intensity of saline water intrusion in shallow groundwater aquifer, independent of the concentration of the solution. With our model we investigated the migration of saline water through a fault or an erosional channel which both allows an exchange between the shallow freshwater and the deeper saline water complex. The salinization potential of a drinking water well in vicinity to the brine source was determined for different scenarios.

Beschreibung: Ziel der vorliegenden Arbeit ist die Erforschung der Subsidenzgeschichte des südlichen Segmentes des Südatlantiks. Die Subsidenzgeschichte wird aus Paleobathymetrien abgeleitet, die basierend auf Informationen der heutigen strukturellen Konfiguration und des thermischen Feldes der Kontinentalränder rekonstruiert werden. Diese Herangehensweise liefert genauere als die bislang vorliegenden Erkenntnisse bezüglich der post-rift Subsidenz. Darüber hinaus lassen die Ergebnisse der vorliegenden Arbeit Rückschlüsse auf die Mechanismen zu, welche die Subsidenzgeschichte beeinflusst haben.Im ersten Teil dieser Arbeit wird eine 1D Rückwärtsmodellierung durchgeführt, um Paleobathymetrien des Kontinentalrandes vor SW Afrika zu rekonstruieren. Für diese Rekonstruktion werden einzelne Subsidenzkomponenten entsprechend der sedimentären Last und der thermischen Abkühlung der Lithosphäre separiert. Der Betrag der last-induzierten Subsidenz wird berechnet, indem durch „backstripping“ einzelne Sedimentpakete, beginnend mit dem heutigen Zeitpunkt, schrittweise entfernt werden. Im Gegensatz dazu wird der Betrag der thermischen Subsidenz unter der Annahme uniformer Lithosphärendehnung berechnet. Unter Berücksichtigung beider Subsidenzkomponenten ist es schlussendlich möglich, Paleobathymetrien zu rekonstruieren und daraus die Subsidenzgeschichte abzuleiten. Die Ergebnisse zeigen, dass der SW Afrikanische Kontinentalrand durch die Zeit abgesunken ist, jedoch einzelne Phasen vertikaler Aufwärtsbewegungen (d.h. Meeresboden-Hebung) auftraten. Letztere lassen sich durch Erhebungen oberhalb des Meeresspiegels identifizieren und belaufen sich auf einen Gesamtbetrag von 1200 m für die Gesamtdauer der post-rift Phase. Ihr zeitliches Auftreten und ihre Magnitude geben Hinweise darauf, dass ein Mantel-Mechanismus für die Hebung verantwortlich ist.Um die Subsidenzentwicklung der passiven Kontinentalränder des Südatlantiks genauer zu verstehen, ist zusätzlich eine Erforschung des konjugierten Kontinentalrandes vor SE Südamerika notwendig. Aus diesem Grund wird im zweiten Teil der Arbeit das Colorado Becken vor der Küste Argentiniens auf seine Subsidenzentwicklung hin untersucht. Für diese Untersuchung wird der heutige Zustand der strukturellen Konfiguration des Colorado Beckens verwendet und dabei dieselbe Methode genutzt, wie sie im ersten Teil der Arbeit für das Untersuchungsgebiet vor SW Afrika verwendet wurde. Im Gegensatz zu dem Sedimentbecken am konjugierten Kontinentalrand SW Afrikas mit seinen Phasen der Meeresboden-Hebung ist im Colorado Becken seit dem Aufbrechen Gondwanas ausschließlich kontinuierliche Subsidenz zu erkennen. In Bezug auf die charakteristische Subsidenzentwicklung beider Kontinentalränder ist es den Ergebnissen nach eher unwahrscheinlich, dass einzig „Ridge-Push“ (durch Spreizung des Südatlantiks) eine treibende Kraft für etwaige Hebung ist, da diese sich auf beide Seiten des Südatlantiks mit einer ähnlichen Stärke auswirken sollte. Diese Erkenntnis stützt die Hypothese eines Mantelmechanismus, welcher Einfluss auf die Subsidenzgeschichte des SW Afrikanischen Kontinentalrandes genommen hat.Im dritten Teil der Arbeit wird eine 3D Vorwärtsmodellierung entlang des SW Afrikanischen Kontinentalrandes durchgeführt und mit den vorherigen Ergebnissen der 1D Rückwärtsmodellierung verglichen. Die 3D Vorwärtsmodellierung hat den Vorteil, dass neben der Subsidenz während post-rift Phase auch die der syn-rift Phase berücksichtigt wird. Zusätzlich werden thermische und mechanische Prozesse während der post-rift Phase gekoppelt, sodass die Wechselbeziehung zwischen thermischem Abkühlen der Lithosphäre und flexurell-isostatischer Kompensation durch Sedimentauflast berücksichtigt wird. Die Ergebnisse zeigen, ähnlich wie die der 1D Rückwärtsmodellierung, Erhebungen oberhalb des Meeresspiegels gleicher Magnitude, jedoch mit leicht unterschiedlichem zeitlichem Auftreten. Allerdings lassen die Ergebnisse der Vorwärtsmodellierung eine starke Abhängigkeit zur syn-rift Phase erkennen. Unter Berücksichtigung methodischer Einschränkungen bei der Rekonstruktion der syn-rift Phase zeigt sich, dass die Erhebungen oberhalb des Meeresspiegels auf fehlende Subsidenz während der syn-rift Phase zurückzuführen sind. Diese könnte mit möglichem Fließen der Unterkruste während der syn-rift Phase zusammenhängen, welches bei der Vorwärtsmodellierung nicht berücksichtigt wird. Die beschriebenen Untersuchungen zeigen, dass eine Analyse der Subsidenzgeschichte unter Verwendung von Informationen über die heutige Konfiguration der Kontinentalränder möglich ist. Aus den Ergebnissen lässt sich folgern, dass die Subsidenzgeschichte des SW Afrikanischen Kontinentalrands sehr wahrscheinlich durch einen Mantelmechanismus beeinflusst wurde, welcher für die Meeresbodenhebung verantwortlich ist. Even though the present-day structure of the South Atlantic passive continental margins has been thoroughly investigated, uncertainties remain, particularly regarding the subsidence evolution during the post-rift phase and its causative processes. This thesis therefore focuses on the subsidence history of the passive continental margins within the Southern Segment of the South Atlantic Ocean. The subsidence history is inferred from restored paleobathymetries along the passive margins using their present-day structural configuration as well as their thermal field.In a first part of this thesis a 1D backward modelling approach is used to reconstruct the paleobathymetries offshore SW Africa. Therefore, individual subsidence components are separated according to the load induced by the sediments and the thermal cooling of the lithosphere. Starting from the present-day configuration, sedimentary units are successively “backstripped” to quantify the amount of load induced subsidence. The amount of thermal subsidence is calculated assuming uniform stretching of the lithosphere. Considering both subsidence components allows reconstructing paleobathymetries of the SW African margin in order to infer its subsidence history. The results obtained show a general subsidence of the margin with intermittent phases of seafloor uplift, as indicated by elevations above sea level in some parts of the research area. Summing up, the amount of elevations above sea level (i.e., seafloor uplift) during the post-rift phase yields about 1200 m. Although this quantification cannot fully identify the causative processes behind the vertical movements, their timing and magnitude give evidence for a mantle mechanism causing seafloor uplift rather than ridge-push related to spreading of the South Atlantic Ocean.Improving the understanding of the subsidence evolution of the South Atlantic passive margins requires also a subsidence analysis along the conjugate margin offshore SE South America. Hence the Colorado Basin along the Argentine margin is investigated. To accomplish this, the present-day structural configuration of the Colorado Basin is used and the same subsidence analysis used to analyse the SW African margin is applied. The results of the backward modelling approach show continuous subsidence of the Colorado Basin since the breakup of Gondwana. Therefore, they are in contrast with the subsidence history of the sedimentary basin on the conjugate margin, where the general subsidence pattern was interrupted by multiple phases of seafloor uplift. In terms of causative processes responsible for the subsidence history, a tectonic force alone, such as ridge-push due to seafloor spreading, is unlikely to cause the seafloor uplift along the SW African margin, since the effects of ridge-push should have the same impact on both margins. This further supports the hypothesis of a mantle mechanism rather than ridge-push as cause for the seafloor uplift along the SW African margin.Finally, to assess how far the obtained seafloor uplift is influenced by the assumptions of the 1D backward modelling and in order to also take the initial syn-rift subsidence into account, 3D forward modelling is performed for the same research area along the SW African margin as in the first part of this work. The 3D forward modelling approach used in this study has the particular advantage of coupling the thermal and mechanical subsidence components. Hence, the interaction between thermal relaxation of the lithosphere and the flexural isostatic response due to sedimentary loading, as well as the interplay of both is considered. The results also indicate elevations above sea level with a similar magnitude, as shown in the backward modelling approach and only minor temporal variations. Following the interpretation of the forward modelling results, it appears that the elevations above sea level are strongly related to the syn-rift phase. Taking the limitations of the approach used to reconstruct the syn-rift phase into account leads to the conclusion that the elevation above sea level might be the result of missing subsidence during the syn-rift phase. This missing subsidence component might be related to unconsidered lower crustal flow while calculating the syn-rift subsidence. According to the previously described approaches, a successful analysis of the subsidence history of the South Atlantic passive continental margins based on present-day observations is possible. After summarizing the results of the three parts of this work and integrating them into a comprehensive discussion of the possible causative processes behind the evolution of the South Atlantic passive continental margins, it is evident that a mantle mechanism affected the SW African margin causing phases of uplift.

Beschreibung: Solar modulated variations in cosmogenic radionuclide production provide both information on past changes in the activity of the Sun and a global synchronization tool. However, to date the use of cosmogenic radionuclides for these applications is almost exclusively based on 10Be records from ice cores and 14C time-series from tree rings, all including archive-specific limitations. We present the first 10Be record from annually laminated (varved) lake sediments for the Lateglacial-Holocene transition from Meerfelder Maar. We quantify environmental influences on the catchment and, consequently, 10Be deposition using a new approach based on regression analyses between our 10Be record and environmental proxy time-series from the same archive. Our analyses suggest that environmental influences contribute to up to 37% of the variability in our 10Be record, but cannot be the main explanation for major 10Be excursions. Corrected for these environmental influences, our 10Be record is interpreted to dominantly reflect changes in solar modulated cosmogenic radionuclide production. The preservation of a solar production signal in 10Be from varved lake sediments highlights the largely unexplored potential of these archives for solar activity reconstruction, as global synchronization tool and, thus, for more robust paleoclimate studies.

Beschreibung: In this study we investigated conditions for loss of GPS signals observed by the Swarm satellites during a 2 year period, from December 2013 to November 2015. Our result shows that the Swarm satellites encountered most of the total loss of GPS signal at the ionization anomaly crests, between ±5° and ±20° magnetic latitude, forming two bands along the magnetic equator, and these low-latitude events mainly appear around postsunset hours from 19:00 to 22:00 local time. By further checking the in situ electron density measurements of Swarm, we found that practically, all the total loss of GPS signal events at low latitudes are related to equatorial plasma irregularities (EPIs) that show absolute density depletions larger than 10 × 1011 m−3; then, the Swarm satellites encountered for up to 95% loss of GPS signal for at least one channel and up to 45% tracked less than four GPS satellites (making precise orbit determination impossible). For those EPIs with density depletions less than 10 × 1011 m−3, the chance of tracked GPS signals less than four reduces to only 1.0%. Swarm also observed total loss of all GPS signal at high latitudes, mainly around local noon, and these events are related to large spatial density gradients due to polar patches or increased geomagnetic/auroral activities. We further found that the loss of GPS signals were less frequent after appropriate settings of the Swarm GPS receivers had been updated. However, the more recent period of the mission, e.g., after the GPS receiver settings have been updated, also coincides with less severe electron density depletions due to the declining solar cycle, making GPS loss events less likely. We conclude that both lower electron density gradients and appropriate GPS receiver settings reduce the probability for Swarm satellites loss of GPS signals.

Beschreibung: A sample from chromite horizon UG1 of the platiniferous Bushveld complex (South Africa) is studied by scanning X-ray fluorescence (XRF) microanalysis using synchrotron-radiation beams from the VEPP-3 storage ring. The sample contains plagioclase and chromite layers 3–5 mm in thickness. The experimental study is conducted at excitation energies of 15 and 30 keV; the spot size of the excitation radiation is 0.1 ± 2 mm; and the scanning step is 100 µm. The distribution profiles of more than 20 trace elements over the surface of the sample are obtained.

Beschreibung: In this study we examine an interesting occurrence of miarolitic pegmatites in the Königshain granite of the Lusatia region of the Bohemian Massif. This granite is characterized by the extensive development of micro-sized miarolitic pegmatites (typically with diameters of 5 to 15 mm) irregularly distributed through its upper levels, and larger miarolitic pegmatites (up to 1 m) in the uppermost levels. This granite also shows evidence of varied forms of transport of extremely volatile rich residual melts/fluids, in the form of more or less discrete inter-granular melt bodies, and associated magmatic quartz veins formed in tectonic fissures. Together, these provide evidence for the origin of miarolitic pegmatites, both in the specific case of Königshain, and more generally. Our evidence suggests that miarolitic pegmatites form from volatile- and alkali-rich residual melts, ranging from 10 to 50% H2O, far more than typical granitic melts, but far more silicate components than aqueous fluids or vapor suggested by some authors. Using melt inclusions in quartz from the aplitic and graphic granite zones in miarolitic pegmatites in the Königshain granite, we show that two different inclusion populations are present. We provide evidence that the first inclusion population are those related to the primary granite at the level of intrusion, and the second were trapped during the re-crystallization of the granite wall rocks by silicate-rich supercritical fluids moving through the solid crystal framework with a porosity 〈 25 and a permeability 〉 0 (see Clarke et al., 2013). Our results show that a significant volume fraction of the miarolitic pegmatites was not created by a pegmatite-forming fluid, but formed in-situ by re-crystallization of wall-rocks, triggered by highly reactive volatiles exsolved from the pegmatite-forming melts. Evidence is also presented which suggests the nature and speed of emplacement of the Königshain granite. This evidence may explain the unusual form and abundance of miarolitic pegmatites in the studied area, and may have application to similar occurrences. Thus, there is a mixture of features which are applicable to miarolitic pegmatites in general, and others which help separate the overriding processes, from the variations produced by local or regional chemical or tectonic characteristics.

Beschreibung: Data publication is increasingly regarded as important scientific achievement and data publications are now fully citable in journal articles. This paper focuses on improving the reusability of data publications by providing comprehensive data descriptions complementary to standardized metadata. In this context, data reports proved to be a helpful tool to fill the gap between restricted ’README’ information on one hand and preparing an extended peer-reviewed data article on the other hand.

Beschreibung: Varved lake sediments provide a unique opportunity to validate results of isotope dating methods. This allows testing of different numerical models and constraining procedures to produce reliable and precise chronologies. Here we present results of the model testing and validation by multiple dating approaches for the varved sediment record from Lake Żabińskie (northeastern Poland). Our goal was to assess possible deviations of 210Pb-derived ages from true sediment ages provided by varve chronology and to check how different numerical procedures can improve the consistency of the chronologies. Different methods for age estimation were applied including varve counting, 210Pb, 137Cs, 14C and tephra identification. Microscopic analysis of the varve microfacies revealed that laminations found in Lake Żabińskie were biogenic (calcite) varves. Three independent counts indicated a good preservation quality of laminae in the sediment profile which contained 178+4/-8 varve years. The calendar-year time scale was verified with two maxima of 137Cs activity concentrations in the sediments (AD 1963 and 1986) and a terrestrial leaf dated to AD 1957-1958 by the 14C method. Additionally, geochemical analysis of the glass shards found in the sediments indicated a clear correlation with the Askja AD 1875 eruption of Iceland which provided an unambiguous verification of the varve chronology. For testing 210Pb dating we used two routinely applied models: Constant Flux Constant Sedimentation (CFCS) and Constant Rate of Supply (CRS). None of the models in their standard forms produced a chronology consistent with varve counts and independent chronostratigraphic markers. Both models yielded ages much younger than the calendar age with a difference of ca. 50 years at the bottom part of the profile. However, a significant improvement was introduced after using the composite CFCS model with sediment accumulation rates calculated for different zones of the sediment profile. This provided highly consistent values along the time scale with deviations 〈5 yrs compared with calendar ages. Also constraining the CRS model with 137Cs peaks as well as testing the correction values for incomplete 210Pb inventory provided results that finally deviated from the calendar age only by ≈10 yrs for the 120 years old sediments.