ALBERT

Description: 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.

Description: 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.

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

Description: Bei phreatischen Eruptionen fehlen häufig warnende Vorzeichen. Der plötzliche Ausbruch des japanischen Vulkans Ontake im Herbst 2014 traf viele unvorbereitet.

Description: Phreatic eruptions often occur without any forewarning. Many were unprepared for the sudden eruption of Ontake volcano, Japan in autumn 2014.

Description: Subduction earthquakes are the most powerful naturally occurring terrestrial processes often resulting in catastrophic fatality counts and decimation of human infrastructure. Over the past decades, great efforts have been undertaken to improve the understanding of the subduction earthquake physics. The Integrated Plate Boundary Observatory in Chile (IPOC) is a multi-instrument network installed in 2007 in the Northern Chile Seismic Gap, where a large magnitude earthquake was expected soon. On April 1st 2014, a portion of the IPOC-monitored region broke, producing the Mw 8.1 Iquique earthquake. In the year leading up to this event, IPOC’s instruments captured some unusual transient seismic and geodetic signals, resulting in a unique dataset recording the preparatory phase of a large earthquake. We combined IPOC data with satellite radar interferometry (InSAR) data to analyze not only the earthquake itself but also the interseismic phase and a detailed foreshock series before the main event. We found that the earthquake ruptured a zone on the plate interface that was highly locked before the earthquake. Additionally, we were able to characterize the aseismic (silent) slip that occurred in the two weeks leading up to the event by combining seismic and geodetic data. Application of these analyses in real-time might enable geoscientists to identify runaway processes that can precede large subduction earthquakes.

Description: Rupture processes show strong similarities on broad spatial scales suggesting that in parts the governing physics for microcrack formation in the laboratory or a large earthquake along a tectonic plate boundary are the same. We discuss examples ranging from rock deformation experiments in the laboratory under controlled boundary conditions, induced seismicity in mines and geological reservoirs to natural earthquakes posing tremendous seismic hazard to population centers. We describe fundamental relations for the entire bandwidth of rupture processes involving fractures, faults and shear zones and their seismic characteristics such as b-value or seismic source properties. Laboratory tests on small-scale rock samples allow studying aspects of processes that control earthquake nucleation and rupture propagation. However, up-scaling of laboratory results to the field scale requires that dominant deformation processes remain the same on vastly different scales, and that potential effects of changing kinematic boundary conditions may successfully be accounted for by appropriate constitutive equations. Our approach shows that constitutive models capturing fundamental physical processes on the laboratory scale may be successfully applied to improve process understanding of deformation on the field scale with the potential to improve seismic hazard estimation.

Description: Seismology is often associated with the investigation of earthquake processes and indeed this is a very important target of the science. However, seismology is also the primary means by which we can obtain images of the internal structure of the Earth on all scales, ranging from the deep interior, i.e. the Earth’s core and lower mantle over the mantle lithosphere and crust, the scale at which plate tectonics ‘happens’ all the way to the unconsolidated material in the near-surface. Seismology uses earthquakes and artificial sources as signal generators but also the ambient background wavefield, previously considered to be merely noise. Methodological and instrumental innovations have allowed ever more detailed investigations of the earthquake process and the seismic structure, and opened up new targets such as as the monitoring of geomorphological events and investigations of the time-dependency of seismic structure. Finally seismology is not restricted to waveform analysis and the instrumental period but draws on historical data and, in the field of paleoseismology, geological markers to constrain seismic activity in the pre-instrumental past. Direct societal benefits from seismology accrue for example from improved seismic hazard estimates and early-warning technologies in the area of natural hazards, from improved recovery and usage of natural resources, including geothermal energy as a sustainable energy source and much more, e.g. the possibility to monitor and thus enforce compliance with the nuclear test ban treaty.

Description: Deep seismic sounding provides important information on the seismic structure of the crust. Seismic experiments make use of controlled sources (explosions, Vibroseis) or natural sources (earthquakes, ambient noise), or combinations of both types. Seismic velocities are derived from modelling or tomographic inversion of diving waves and refractions. Particularly the combined interpretation of compressional and shear velocities allows for insight into the lithological structure of the crust. Seismic reflectivity is derived from imaging of waves reflected at geological boundaries. Typical patterns of crustal reflectivity are observed for specific tectonic settings. Case studies are shown from two studies at plate boundary systems. (1) The old plate boundary at the Namibian margin was formed by Cretaceous continental rifting and its interplay with the activities of the Tristan da Cunha mantle plume. Traces of intensive magmatic overprinting of the crust at the landfall region of Walvis Ridge can be seen in the derived velocity model and also in the reflectivity image. (2) The Dead Sea transform marks the active boundary between the African and Arabian plates. The Dead Sea basin was formed by pull-apart in response to step-over of the fault system. Results from tomography reveal a deep asymmetric basin structure. An anomalous body was found under the basin, between 13 and 18 km depth, which is interpreted as pre-basin sediments. Our results are supported by the distribution of earthquakes. The results provide new constraints for the modeling of plate boundary processes.

Description: Für erfolgreich betriebene Wissenschaft ist es unerlässlich, als Forschender auf seinem Fachgebiet die neuesten Entwicklungen zu verfolgen. Dafür bietet Current Awareness (CA) Wissenschaftlern eine Reihe von kommerziellen Services und Dienstleistungen an, aber auch Alternativen wie das Suchportal ALBERT. Mit dieser Arbeit wird die Funktion von ALBERT als CA-Service hinsichtlich Aktualität und Informationsbedarf von Wissenschaftlern untersucht. Der erste Teil der Arbeit vergleicht die Erfassungsgeschwindigkeit von Metadaten von Artikeln in ALBERT mit den etablierten Datenbanken Web of Science, Scopus und PubMed. Im zweiten Teil der Arbeit werden auf Grundlage von Experteninterviews Aspekte ausgewertet und diskutiert, die in Zusammenhang mit dem Stellenwert von CA in der aktuellen Forschung und einer bibliothekarischen Dienstleistung dazu stehen. Komplettiert wird die Arbeit mit einer Auseinandersetzung der technischen Dimension un der Metadatenqualität eines CA-Services.

Description: The nucleation of earthquakes and their seismic waves cannot be predicted in a deterministic sense. However probabilistic hazard and risk estimations can be conducted which help to increase the preparedness and reduce the vulnerability of societies. Those estimations are based on the rapidly growing number of empirical earthquake data recorded by seismic networks or known from historical or geological studies, which show that earthquakes are not randomly occurring. They typically occur clustered in space and time with specific characteristics such as the Gutenberg-Richter law for the frequency-magnitude distribution. Seismicity models have to account for earthquake interactions to avoid erroneous estimations of the activity level and spatial distribution of future activity. Additionally, the vulnerability of societies is changing with with time, because of the dynamic reconstruction and growth of cities in earthquake-prone regions. Thus new sophisticated models, strategies, and methods have to be developed and tested for all components of the earthquake risk chain to improve our probabilistic hazard and risk estimations.

Description: Diese Ausgabe des GFZ-Journals „System Erde“ wurde im Dezember 2016 produziert und erscheint im Januar 2017. Das ist der Monat, in dem das Deutsche GeoForschungsZentrum seinen 25. Geburtstag feiert. Der Schwerpunkt Südamerika ist dabei durchaus passend, denn die Forscherinnen und Forscher des GFZ arbeiten dort seit der Gründung des Zentrums. Die Südpazifikküste mit den großen Subduktionsbeben, die Anden mit ihren Vulkanen und all die geologischen Prozesse, die in der Region sichtbar werden, sind wie die Seiten eines Lehrbuchs der Geologie – wenn man sie denn zu entziffern weiß. Selbst die so genannten passiven Kontinentalränder an den Küsten des Südatlantiks bieten uns tiefe Einblicke in die Erdgeschichte; sie sind Geoarchive erster Ordnung. Hinzu kommt, dass sie Lagerstätten für Rohstoffe bergen.

Description: Seismic interferometry is a methodology to recover the signals of waves propagating between seismic stations from records of random wavefields such as the ambient seismic noise or the coda of an earthquake. Teleseismic body waves excited by a very deep earthquake close to Kamchatka are investigated to unveil the composition of the teleseismic wavefield at long propagation times which is key to understand how teleseismic waves can be reconstructed by seismic interferometry. Waves at high frequencies around 1s period are shown to be scattered strongly in the Earth crust where they are quickly attenuated. At low periods, seismic waves circle the Earth for many hours as surface waves with clear arrivals of the different orders. At intermediate periods around 40s waves still propagate for several hours but individual arrivals cannot be identified in the data any more – indicating a randomization process. It is shown here that to a large extent this randomization is due to the interaction with the Earth’s 1D structure that does not alter the azimuthal distribution of the wavefield. Even after 8 h the seismic energy propagates dominantly along the great circle and the mean free time of the azimuthal randomization is estimated to 10 h. This means that the recovery of the teleseismic wavefield by seismic interferometry is strongly dependent on the distribution of ambient sources. For a successful application of seismic interferometry sources need to be present at suitable distances on the great circle connecting the stations.

Description: The warm water geothermal reservoir below the village of Waiwera in New Zealand has been known by the native Maori for centuries. Development by the European immigrants began in 1863. Until the year 1969, the warm water flowing from all drilled wells was artesian. Due to overproduction, water up to 50 °C now needs to be pumped to surface. Further, between 1975 and 1976, all warm water seeps on the beach of Waiwera ran dry. Within the context of sustainable water management, hydrogeological models must be developed as part of a management plan. Approaches of varying complexity have been set-up and applied since the 1980s. However, none of the models directly provide all results required for optimal water management. Answers are given simply to parts of the questions, nonetheless improving resource management of the geothermal reservoir.

Description: Das geothermische Warmwasserreservoir unterhalb der Kleinstadt Waiwera in Neuseeland ist seit vielen Jahrhunderten bei den Ureinwohnern, den Maori, bekannt. Die Nutzung durch die europäischen Einwanderer begann 1863. Bis in das Jahr 1969 waren die bis dahin abgeteuften Förderbohrungen für das warme Wasser artesisch. Ausgelöst durch eine Überproduktion muss das bis zu 50 °C heiße Wasser heute mit Pumpen gefördert werden. In den Jahren 1975 und 1976 kam es zusätzlich zum Versiegen der Warmwasserquellen am Strand von Waiwera. Im Rahmen einer nachhaltigen Wasserbewirtschaftung ist es notwendig, hydrogeologische Modelle einzusetzen. Unterschiedlich komplexe Ansätze wurden seit den 1980er- Jahren umgesetzt. Keines der Modelle liefert allerdings direkt alle für dasWassermanagement benötigten Ergebnisse. Es werden jeweils Antworten auf Teilaspekte gegeben, die das Ressourcenmanagement des geothermischen Reservoirs verbessern.

Description: The Atacama Fault System (AFS) is an active trench-parallel fault system, located in the forearc of N-Chile directly above the subduction zone interface. Due to its well-exposed position in the hyper arid forearc of N-Chile it is the perfect target to investigate the interaction between the deformation cycle in the overriding forearc and the subduction zone seismic cycle of the underlying megathrust. Although the AFS and large parts of the upper crust are devoid of any noteworthy seismicity or historically documented earthquakes, at least three M=7 earthquakes in the past 10 ky have been documented in the paleoseismological record, demonstrating the potential of large events in the future. We apply a two-fold approach to explore fault activation and reactivation patterns through time and to investigate the triggering potential of upper crustal faults. 1) A new methodology using high-resolution topographic data allows us to investigate the number of past earthquakes for any given segment of the fault system as well as the amount of vertical displacement of the last increment. This provides us with a detailed dataset of past earthquake rupture of upper plate faults which is potentially linked to large subduction zone earthquakes. 2) The IPOC Creepmeter array provides us with high-resolution time series of fault displacement accumulation for eleven stations along the four most active branches of the AFS.

Description: Film 7: "Die Stilllegung eines CO2-Speichers – Pilotstandort Ketzin" (Länge 10:39) Produktionsjahr: 2015

Description: In news reports we are accustomed to see earthquakes symbolised with a dot or star on a map and associated with a magnitude, the bigger the scarier. For at least moderately sized earthquakes seismologists additionally have been routinely determining the type of rupture just from observing the pattern of radiated seismic energy. In reality earthquakes do not occur as a point but rupture a fault plane. For small earthquakes this distinction can be neglected but for the largest earthquakes the rupture plane can extend for hundreds of kilometres, and the actual rupture propagation begins to have a strong influence on the hazard that the earthquake presents – whether the rupture proceeds to the north or the south and how deep and shallow it reaches determines which cities will be hit the hardest, whether shaking is moderate or intense, and whether a sizeable tsunami is triggered. The explosion of the availability of ground-, ocean- and space-based observation technologies in the last decade has allowed seismologists to map the rupture process in unprecedented detail even for challenging subduction zone earthquakes. The same technology can be used to observe potential precursory processes and the postseismic relaxation by which the earth regains its equilibrium following the disturbance that a great earthquake represents. Focussing on the Mw 8.1 Iquique earthquake in northern Chile on April 1, 2014, we will discuss the state-of-the-art in monitoring great earthquakes and their aftermath.

Description: The possibility of seismic risk mitigation in high hazard region like Central Asia requires the availability of strong motion recordings.When available also in real time, they can be precious for enabling early warning systems and efficient rapid response procedure. TheACROSS project is implementing the installation of the first real time strong motion network for Central Asia. It offers the opportunityfor developing, testing and implementing new methodologies for strong motion data analysis in real time, improving the transfer ofknowledge from research to application.

Description: Significant scientific findings are often directly related to innovations in measurement technology. For investigating the Earth’s interior the invention of the seismography played the most important role. Starting with the first seismograph suitable for scientific investigations by Ewing, Gray and Milne in the 1870s and its improvement by Wiechert around 1900, seismic instrumentation was available in the beginning of the last century to reveal the layered structure of our planet. Since then, instruments were steadily improved, and controlled source experiments and seismic networks significantly contribute today to our understanding of the Earth’s structure and the ongoing dynamic processes as well as to the exploration of resources as oil, gas, water and minerals. At the GFZ German Research Centre for Geosciences we work on technical innovations and apply them in experiments around the world and at a variety of scales. We develop highly portable, low-cost, high-performance seismic data recording systems, which are designed to be used in “large-N” array configurations (〉1000 receivers) and on the sea floor (shallow water). Distributed accoustic sensors (DAS) based on fibre-optic cables allow extremely dense sampling of the seismic wavefields. Seismic sources and receivers integrated in borehole tools illuminate in high-resolution the subsurface during drilling operations (Seismic prediction while drilling, SPWD).

Description: Das Wissen um die lokale Struktur von Seltenen Erden Elementen (SEE) in silikatischen und aluminosilikatischen Schmelzen ist von fundamentalem Interesse für die Geochemie der magmatischen Prozesse, speziell wenn es um ein umfassendes Verständnis der Verteilungsprozesse von SEE in magmatischen Systemen geht. Es ist allgemein akzeptiert, dass die SEE-Verteilungsprozesse von Temperatur, Druck, Sauerstofffugazität (im Fall von polyvalenten Kationen) und der Kristallchemie kontrolliert werden. Allerdings ist wenig über den Einfluss der Schmelzzusammensetzung selbst bekannt. Ziel dieser Arbeit ist, eine Beziehung zwischen der Variation der SEE-Verteilung mit der Schmelzzusammensetzung und der Koordinationschemie dieser SEE in der Schmelze zu schaffen.

Description: Knowledge of the local structure around rare earth elements (REE) in silicate and aluminosilicate melts is of fundamental interest for the geochemistry of magmatic processes, particularly for comprehensive understanding of the partitioning processes of REE in magmatic systems. It is generally accepted that mineral-melt partitioning of REE’s is controlled by temperature, pressure, oxygen fugacity (in case of polyvalent cations) and crystal chemistry but less is known about the influence of the melt composition. The aim of this thesis is to establish a relationship between the variation of the REE distribution with the melt composition and the coordination chemistry of this REE in the melt.

Description: Volcanic activity involves different processes on different scales at depth and at the surface. Many of them generate seismic signals, ranging from tiny, earthquake-like signals to increased continuous vibrations to significant ground motion events before and during volcanic eruptions. A range of modern tools of volcano seismology is nowadays used to monitor changes in the volcanic activity and volcanic unrest. Additionally, advanced seismology is able to image the deep volcanic structures at high resolution and to map the depth and size of magmatic reservoirs beneath volcanoes. Although seismology is a key technology for volcano research and the assessment of volcanic hazard, novel concepts of volcano monitoring combine seismology with different types of multi-parameter sensors to characterize the processes accompanying volcanic unrest. GFZ is developing advanced approaches for volcano monitoring and volcano modeling involving a broad scale of instruments and disciplines. The article focuses mainly on two examples from volcanoes in South America and Iceland showing how large magmatic reservoirs are slowly filled over periods of decades and abruptly depleted over periods of months during volcanic eruptions.

Description: Sedimentary basins represent geological archives. Accordingly, 3D basin models that integrate geological and geophysical observations can be used to reproduce not only their present-day structural configuration and distribution of physical properties, but also their evolution including the subsidence history. For example, the thickness of deposited sediments reflects the amount of subsidence caused by the sediment load. The corresponding load-dependent vertical movements (called isostatic subsidence) can be sequentially subtracted from the total subsidence in order to reconstruct past depth configurations. Another aspect of basin subsidence is caused by thermal processes that can also be approximated by studying the present-day basin configuration. If the basin formation is related to lithospheric stretching and thinning, it initially involves a thermal disturbance due to which the geothermal gradient is increased by an amount depending on the observed strain. After stretching has ceased, the lithosphere starts cooling down and approaches a thermal equilibrium. This cooling process is accompanied by an increase in rock density and related thermal subsidence, which can also be assessed. By calculating the two subsidence components for certain stratigraphic intervals, the corresponding temporal changes in water depths (paleobathymetries) can be reconstructed for our understanding of subsidence dynamics. This research methodology was applied to the conjugate passive continental margins of Africa and Argentina in order to analyse and compare the evolution of sedimentary basins after the formation of the South Atlantic. This study mainly focussed on the Argentinian Colorado Basin because of its complex evolution and economic resource potential.

Description: Very long baseline interferometry (VLBI) is one of the fundamental space geodetic techniques. Important goals for the next generation of VLBI technology are continuous operations as well as automated data processing. For this reason, it is necessary to introduce real time capable parameter estimation algorithms, such as Kalman filters, to VLBI data analysis. In this study, such a filter was implemented in the VLBI software VieVS@GFZ, and several aspects related to VLBI data processing were investigated. Within the corresponding module VIE_KAL it is possible, for example, to estimate all parameters important in VLBI analysis, adapt their stochastic models, flexibly define the datum, integrate external data, as well as extract datum free normal equations. The foci of the investigations were on the effects of the troposphere, the most important error source in VLBI analysis, and on the determination of station positions, which are of great importance in geodesy. For the stochastic model of the tropospheric delays, station- and timedependent differences were considered. In comparisons with tropospheric parameters from GNSS, water vapor radiometers and numerical weather models, the Kalman filter solution yielded 5 to 15% smaller differences than a least squares solution based on the same models and VLBI data. Also in the case of estimated station coordinates, the Kalman filter solution exhibited better baseline length and station coordinate repeatabilities. The application of station-based process noise led to additional improvements. Furthermore, the Kalman filter was used to estimate subdaily station coordinate variations caused by tidal and loading effects. Finally, the findings were used to determine Kalman-filter-based global terrestrial reference frames (TRFs). For the stochastic model of the coordinate variations of particular stations, loading deformation time series were utilized. The non-deterministic approach of the Kalman filter allowed the consideration of non-linear station movement, for example, due to irregular seasonal effects or post-seismic deformations. In comparisons with a VLBI TRF solution from a classical adjustment and ITRF2008, a good agreement in terms of transformation parameters and station velocities was achieved. The findings from testing different options related to the parameterization and to the stochastic model will help to improve future reference frames.

Description: Seismic hazard assessments can only be as good as the historical past is known. Therefore, reliable seismicity records have to be extended back into history as far as possible. Hence, historical seismological investigation is of utmost importance in order to achieve long-term earthquake catalogue data of high quality. This basic research has been performed at the GFZ German Research Centre for Geosciences as a multidisciplinary approach of seismologists and historians for many years. Seismic activity before the installation of the first seismographs in the beginning of the 20th century can only be reconstructed based on written sources For Central Europe, these documents date back up to the middle of the 8th century. The historical information for each earthquake has to be source-critically analyzed and transferred into parameterized information, which is then catalogued. During the long tradition of collecting past seismic information starting more than a century ago, many mistakes were made, like duplications of events, misinterpreted strength, location and wrong dating of earthquakes, which could be identified by our investigation. We show exemplarily how these uncertainties can be mitigated. Historical passing on of information is transferred to modern seismicity parameters by applying historic-critical methods. Thus, we are able to acquire better and more reliable long-term data for historical earthquake catalogues and for trustworthy long-term seismic hazard assessments.

Description: To this date, the question of why and how a plateau-type orogen formed with massive crustal thickening at the leading edge of western South America remains one of the hotly debated issues in geodynamics. During the Cenozoic, the Altiplano and Puna plateau of the Central Andes developed during continuous subduction of the oceanic Nazca plate in a convergent continental margin setting – a situation that is unique along the 60 000 km of convergent margins around the globe. The key challenge is to understand why a first-order mechanical instability of the later plateau extent developed along the central portion of the leading edge of South America only, as well as why and how this feature developed only during the Cenozoic, although the cycle of Andean subduction had been ongoing since at least the Jurassic. Although the widespread presence of partial melts or metamorphic fluids at mid-crustal level has been suggested to indicate upper plate weakening from heating and partial melting, it is recently found that upper plate strain weakening at lithospheric scale plays a significantly larger role. This first order control is tuned by factors affecting the strength balance between the upper plate lithosphere and the plate interface of the Nazca and South American plates such as variations in trenchward sediment flux affecting plate interface coupling and slab rollback or the role of inherited structures. Late initiation of orogeny in the Eocene, however, and its sustained action over tens of million years is now found to be related to the penetration of the slab into the lower mantle around 50 Ma ago, producing a slowdown of the lateral slab migration (‚slab anchoring’), and dragging the upper plate against the subduction zone by large-scale return flow. The combination of these parameters was highly uncommon during the Phanerozoic leading to very few plateau style orogens at convergent margins like the Cenozoic Central Andes in South America or the Laramide North American Cordillera.

Description: Die Allianz der deutschen Wissenschaftsorganisationen empfiehlt wissenschaftlichen Einrichtungen, Informationen zu gezahlten Open-Access-Publikationsgebühren offenzulegen, damit die Kostenstrukturen des Open-Access-Publikationsmarkts klar erkennbar werden.

Description: The Earth’s surface is constantly changing as material is redistributed by processes like slope failures, debris flows and floods. Although this is a natural part of landscape evolution, we perceive many of these processes as hazards. Especially during their extreme manifestations, they can cause significant damage and even injury and loss of life. The process understanding that is necessary for the safe keeping of the environment that we live in can be obtained by acute observation. Seismic measurements provide distinct advantages over traditional methods. Within a sensor network, many important processes at the Earth’s surface can be observed and identified, along with their meteorological drivers. Further, seismic networks make it possible to monitor the entire landscape without the need of a prior choice of location. In this way, nearly complete event catalogues can be obtained and the interaction of different processes can be studied. The potential of seismic observations of Earth surface processes is illustrated with an example from the Illgraben, Switzerland. There, a two-way interaction between rock slope failures and debris flows was observed during a summer thunderstorm.

Description: The Integrated Plate Boundary Observatory Chile (IPOC) in northern Chile has been monitoring the largest seismic gap along the South American subduction zone for 10 years. When IPOC was initiated, it has been 130 years the last great earthquake in the region had occurred. And since then the Iquique gap had been accumulating a slip deficit along a 〉500 km segment of the plate boundary. Since IPOC’s inception two large events, the 2007 M 7.7 Tocopilla and the M 8.1 2014 Iquique earthquakes, have broken parts of the gap. Both events were well recorded by IPOC, produce valuable data and advance our understanding of the subduction megathrust earthquake cycle. Last year, the Helmholtz Centre for Ocean Research Kiel (GEOMAR) has been extending IPOC with the GeoSEA ocean bottom observatory. In this ambitious project deformation will be measured where it cannot be picked up by land-based instruments, i. e. far offshore near the subduction trench. This will open the crucial updip section of the subduction plate boundary to research. IPOC has thus demonstrated the necessity of long-term monitoring to observe slow or rare events, but also that tenacity and patience pay off.

Description: Hinweis: Dies ist eine vorherige Version aus 2016. Die aktuelle Version aus 2020 ersetzt diese Version der Kriterien zum Umgang mit Open-Access-Publikationsgebühren und der Kriterien zum Betrieb von Open-Access-Publikationsfonds.

Description: Diese Arbeit befasst sich mit der ganzheitlichen Betrachtung der Fluideigenschaften eines unterpermischen Reservoirs am Geothermie Forschungsstandort Groß Schönebeck (GrSk) bei Reservoirbedingungen und im Betrieb der Geothermieanlage. Die Untersuchungen zur Fluidherkunft ergeben, dass es sich um ein konnates Wasser meteorischen Ursprungs ohne den Einfluss der darüberliegenden Zechsteinwässer handelt. Die Ionen und Isotopenverhältnisse im Formationswasser gelöster Komponenten in GrSk belegen einen gemeinsamen Genesepfad mit Wässern anderer Rotliegend-Reservoire des Nordostdeutschen Beckens (NEGB).

Description: The South American continent as we know it formed during the break-up of West Gondwana between 150 and 110 million years ago, when the South Atlantic Rift system evolved into the South Atlantic ocean. Using state-of-the-art global tectonic reconstructions in conjunction with numerical and analytical modelling, we investigate the geodynamics of rift systems as they evolve into an ocean basin. We find that rifts initially stretch very slowly along the future splitting zone, but then move apart very quickly before the onset of rupture. In case of the split between South America and Africa, the divergence rate increased from initially 5 to 7 millimetres per year to over 40 millimetres per year within few million years. Intriguingly, abrupt rift acceleration did not only occur during the splitting of West Gondwana, but also during the separation of Australia and Antarctica, North America and Greenland, Africa and South America, in the North Atlantic or the South China Sea. We elucidate the underlying process by reproducing the rapid transition from slow to fast extension using analytical and numerical modelling with constant force boundary conditions. The mechanical models suggest that the two-phase velocity behaviour is caused by a rift-intrinsic strength–velocity feedback similar to a rope that snaps when pulled apart. This mechanism provides an explanation for several previously unexplained rapid absolute plate motion changes, offering new insights into the balance of plate driving forces through time.

Description: Die DIN 19700:2004-07 "Stauanlagen fordert für Hochwasserrückhaltebecken und Talsperren die Prüfung der Einwirkung von Erdbeben. Ausgehend von der Erdbebengefahr am Standort müssen Nachweise hinsichtlich der Zuverlässigkeit der Stauanlage im Erdbebenfall geführt werden. Für die Betreiber und die Wasserbehörden gibt das vorliegende Kompendium einen zusammenfassenden Überblick über die Grundlagen der Erdbebennachweisführung entsprechend den DIN-Vorgaben. Die Anforderungen an die Nachweisführung sowie eine Leistungsbeschreibung für die zu beauftragenden Fachbüros werden gegeben. Ferner werden Hinweise zum Betrieb der Stauanlage erläutert. Es wird dargestellt, wie die Stauanlagen in Hinsicht auf eine Erdbebeneinwirkung zu überwachen sind.