ALBERT

Description: The intention of this article is to present the definitions of different functionals of the Earth's gravity field and possibilities for their approximative calculation from a mathematical representation of the outer potential. [...] More or less, what is compiled here is well-known in physical geodesy but distributed over a lot of articles and books which are not cited here. In the first instance this text is targeted at non-geodesists and it should be "stand-alone readable".

Description: The final report contains a description of the results obtained within a research contract between IRE RAS and GFZ Potsdam during the period April-November 2004. The objectives of investigation included (1) the radio-holographic methods for obtaining vertical profiles of the vertical gradients of physical parameters in the atmosphere, (2) radio holographic methods for atmospheric, ionospheric and stratospheric waves, and (3) validation of the software with GPS/MET (GPS/METeorology, e.g., Rocken et al. 1997) and CHAMP (CHAllenging Minisatellite Payload, e.g., Reigber et al. 2005) data and final report with recommendations.

Description: Late Miocene to Quaternary volcanic rocks from the frontal arc to the back-arc region of the Central Volcanic Zone in the Andes show a wide range of delta 11B values (+4 to -7 ‰) and boron concentrations (6 to 60 ppm). Positive delta 11B values of samples from the volcanic front indicate involvement of a 11B-enriched slab component, most likely derived from altered oceanic crust, despite the thick Andean continental lithosphere, and rule out a pure crust-mantle origin for these lavas. The delta 11B values and B concentrations in the lavas decrease systematically with increasing depth of the Wadati-Benioff Zone. This across-arc variation in delta 11B values and decreasing B/Nb ratios from the arc to the back-arc samples are attributed to the combined effects of B-isotope fractionation during progressive dehydration in the slab and a steady decrease in slab-fluid flux towards the back arc, coupled with a relatively constant degree of crustal contamination as indicated by similar Sr, Nd and Pb isotope ratios in all samples. Modelling of fluid-mineral B-isotope fractionation as a function of temperature fits the across-arc variation in delta 11B and we conclude that the B-isotope composition of arc volcanics is dominated by changing delta 11B composition of B-rich slab-fluids during progressive dehydration. Crustal contamination becomes more important towards the back-arc due to the decrease in slab-derived fluid flux. Because of this isotope fractionation effect, high delta 11B signatures in volcanic arcs need not necessarily reflect differences in the initial composition of the subducting slab. Three-component mixing calculations for slab-derived fluid, the mantle wedge and the continental crust based on B, Sr and Nd isotope data indicate that the slab-fluid component dominates the B composition of the fertile mantle and that the primary arc magmas were contaminated by an average addition of 15 to 30 % crustal material.

Description: The striking improvements in long- to medium-wavelengths gravity field recovery achieved with GPS-CHAMP and GPS-GRACE high-low and GRACE K-band range low-low satellite-to-satellite tracking prompted us to combine the satellite data with surface data from altimetry over the oceans and gravimetry over the continents to generate a new, high resolution global gravity field model: EIGEN-CG01C. The model is complete to degree/order 360 in terms of spherical harmonics and resolves half-wavelengths of 55 km in the geoid and gravity anomaly fields. A special band-limited combination method has been applied in order to preserve the high accuracy from the satellite data in the lower frequency band of the geopotential and to allow for a smooth transition to the high-frequency band, dominated by the surface data. Compared to pre-CHAMP/GRACE global high-resolution gravity field models, the accuracy was improved by one order of magnitude to 4 cm and 0.5 mgal in terms of geoid heights and gravity anomalies, respectively, at a spatial resolution of 200 km half-wavelength. The overall accuracy at degree/order 360 is estimated to be 20 cm and 5 mgal, respectively, and benefits significantly from recently released new gravity anomaly compilations over the polar regions. In general, the accuracy over the oceans is better than over the continents reflecting the higher quality of the available surface data.

Description: The purpose of this study is to refine the probabilistic seismic hazard assessment for Vanuatu. The analysis is complicated by inconsistencies of the global and local data for the investigated region and systematic inadequacies of the attenuation relation available. An additional aspect in the field of which more research would be desirable is the de-clustering algorithm for the identification of dependent earthquakes. In order to quantify the inevitable uncertainties associated with our results, we used a Logic Tree approach. The report is subdivided into seven chapters. Chapter 2 summarises the geology and tectonic setting of the Vanuatu island arc. Prior scientific investigations will be sketched briefly and to the degree to which they are relevant for our further considerations. The consecutive Chapter 3 describes the different data sources used for the calculations. Together, the local earthquake catalogue provided by the IRD (Institut de Recherche pour le D´eveloppement) and the global catalogues constitute a comprehensive data base for the region. The homogenisation of different catalogues required the conversion of magnitudes through maximum likelihood regressions. Chapter 4 gives a brief overview over the methodological concept applied. The implementation of the Cornell methodology involves two key steps: The first step is to construct a seismicity model (Chapter 5) including the definition of source zones and seismicity parameters characterising the level and type of activity in the respective zone. The second step is to determine an appropriate attenuation relation for the earthquake-generated ground motion in dependence of magnitude and distance. Chapter 6 compares several attenuation relations from the recent geophysical literature. We argue that the modeling of attenuation is the weakest link in this analysis and the major source of uncertainty. The new seismic hazard maps are presented and discussed in Chapter 7. The map that we consider to be the most relevant is also shown on the inner title page of this report. Our findings indicate that the seismic hazard in Vanuatu has been underestimated by prior assessments such as the Global Seismic Hazard Assessment Programme GSHAP (cf. Fig. 1.1).

Description: This manual outlines the characteristics and structure of the software and describes how to use the software. The principles and new features are outlined systematically and referred partly to existing references. Numerical examples of multi-functions and internal tests as well as external comparisons are given.

Description: We review the historical, geological, tide-gauge, GPS and gravimetric evidence advanced in favour of or against continuing land uplift around Hudson Bay, Canada. After this, we reanalyse the tide-gauge and GPS data for Churchill using longer time series than those available to previous investigators. The dependence of the mean rate of relative sea-level change obtained on the length and mid-epoch of the observation interval considered is investigated by means of the newly developed linear-trend analysis diagram. For studying the shorter-period variability of the tide-gauge record, the continuous-wavelet transform is used. The mean rate of land uplift obtained from GPS is based on a new analysis using IGS solutions of GFZ. Furthermore, sea-level indicators from the Churchill region representing the relative sea-level history during the past 8000 a are included. Finally, the four types of observable are jointly inverted in terms of mantle viscosity. The optimum values are 3×10^20 Pa s and 1.6 × 10^22 Pa s for the upper- and lower-mantle viscosities, respectively.

Description: This report is also published as Scientific Report No. 04-9 of the Danish Meteorological Institute.

Description: In this thesis the subduction zone of the Central Andes is studied. The Andes have formed in a complex interplay of subduction related and tectonic processes. The Central Andes with the associated Altiplano-Puna high plateau constitute the second largest continental land-mass on earth, rivaled only by the Tibetan highland. Whereas in the case of the Himalayas , where two buoyant continental plates collide, crustal thickening and uplift is quite intuitive, processes leading to formation of a plateau above a subduction zone are puzzling.

Description: This thesis focuses on the seismic structure of the lithosphere and upper mantle beneath the western Eger Rift area with the aim of investigating deep-lying possible causes of the phenomena observed at surface. For the investigation, data of the international passive seismic experiment BOHEMA carried out in 2002/2003 was used. The BOHEMA network consisted of 61 permanent and 84 temporary stations and was centred on the western Eger Rift. The resulting large data set allowed a high resolution P and S receiver function study using P-to-S and S-to-P converted waves, respectively, to map seismic discontinuities in the lithosphere and upper mantle. Data from an earlier passive seismic experiment was additionally used to complement the BOHEMA data set. The results of the analysis are described in this thesis ‘from top to bottom’. [...] Furthermore, the first map of average crustal vp/vs ratios is presented for the investigated area.

Description: As observed on the Earth's surface, the magnetic field can be separated into three components: The "Main Field", the "Crustal Field" and the "External Magnetic Field". This work concentrates on the magnetospheric current systems, in order to correct the effect of large-scale magnetospheric current systems. Their exact knowledge is vital to improve the main field and secular variation models. Spherical harmonic analysis (SHA) is commonly used to describe the magnetic field. In SHA it is possible to distinguish between internal and external contributions to the Earth's magnetic field. The spherical harmonic coefficients describe dipolar, quadrupolar and higher parts in spherical coordinates. Here, CHAMP (CHAllenging Minisatellite Payload) measurements are used. Due to the inclination CHAMP is changing the orbit in local time. From time to time CHAMP is flying in resonance with the Earth's rotation, i.e. the satellite is flying over the same ground track after a couple of days. To model changes during a period of a few days these so called "repeat tracks" are very helpful for an improved main field/external field model. On the Earth's surface the magnetic effect of magnetospheric currents is often characterised by the DST-indix. In this study, it is explained how a possible constitution of the external sources of the geomagnetic field can look like and how the effect of these magnetospheric currents can be corrected in main field modelling.

Description: The paper consists of two main elements: (1) the creation of a harmonized seismicity data file for the eastern Mediterranean area and the generation of a classical timeindependent PSHA, and (2) the extension of the earthquake model of the timeindependent approach to a newly developed time‐dependent PSHA and the comparison with the results of (1).

Description: Understanding the climate system and the natural processes that lead to its changes is fundamental when trying to evaluate and assess the human influence on climate variability. Human activities characterised most of the Holocene time period, so that palaeoclimate sequences of the last 8,000 years recorded both climate change and human impact. In order to study natural climate variability, we have to investigate past interglacial climate records, when human impact was none. Amongst many palaeoclimate archives, lacustrine varved sequences are invaluable records that allow high resolution palaeoclimate reconstruction. The interglacial lake deposits of Piànico (Southern Alps) consist of ca 15,500 biochemically precipitated calcite varves. The goal of my research is the sedimentological, geochemical and isotopical study at seasonal/decadal resolution of climate variability as recorded in this sequence. The chronology obtained from varve counting constitutes a floating chronology of an interglacial period; the recovery of two tephra layers allowed to fix the floating chronology to the interglacial centred at 400 ka BP, thus corresponding to MIS 11. I studied the upper 5,900 varves at seasonal resolution, using a multi proxy approach. The thickness of summer layers is the proxy for productivity and spring-summer temperature, whereas detrital layers indicate extreme precipitation events; δ18O has been used as a proxy for temperature and/or air masses circulation. I developed a new sampling technique for isotope analyses, in order to ensure the sampling of endogenic calcite, avoiding detrital contamination; this method also allowed me to quantify the effect of Triassic dolomite in bulk carbonate samples. The 15.5 ka of interglacial conditions in Piànico are characterised by short-term climate change. At least four rapid climatic oscillations and a climatic deterioration at the very end of the 15,500 years are recorded. The main climatic oscillation is a 1000 years long cold period that took place after ca 10,000 years of interglacial conditions. This type of climate oscillation has not been recorded in the Holocene yet. This implies that, so far, the Holocene has not experienced all the possible range of interglacial climate changes.

Description: In this report, we will present the complete derivation of analytical expressions of the EM coupling torque in dependence on the parameters of the fields contributing to it. For this, we choose a special set of spherically harmonic (SH) base functions and present all major steps of the derivation. Our report will be (i) closer to a lecture note than to a scientific paper and should give all readers the possibility to follow the derivations with the related details in the appendix, and can be (ii) used as a formulary for scientists working on this special field of investigation.

Description: In der vorliegenden Arbeit werden der Einfluss seismischer Anisotropie auf wahre oder scheinbar auftretende tensile Quellanteile untersucht und Erdbebenmechanismen unter Berücksichtigung seismischer Anisotropie bestimmt. Es wird gezeigt, dass der Momententensor und die Abstrahlmuster eines Scherbruches im anisotropen Medium denen eines tensilen Bruches im isotropen Medium ähneln können. Umgekehrt treten Ähnlichkeiten tensiler Beben in anisotropen Gesteinen mit Scherbrüchen in isotropen Medien auf. Damit existieren Mehrdeutigkeiten beobachteter tensiler Quellanteile. Die Effekte von Anisotropie hängen von der Orientierung des Bruches und vom Grad der Anisotropie ab. Außerdem beeinflusst Anisotropie das Moment eines Bebens. [...] Mit dieser Arbeit werden erstmals zeitliche und räumliche Veränderungen tensiler Quellanteile und Spannungszustände im Vogtland für Erdbeben im Jahr 2000 beob- achtet. Diese haben auch dann Bestand, wenn seismische Anisotropie berücksichtigt wird. Sie können durch Fluide erklärt werden, die in die Bruchflächen eindringen.

Description: Die vorliegende Arbeit beschäftigt sich mit der kombinierten strukturgeologischen und magnetotellurischen Untersuchung eines Segmentes der ’West Fault’-Störung in den nordchilenischen Anden. Die West Fault ist ein Abschnitt des über 2000 km langen Präkordilleren-Störungssystem, welches im Zusammenhang mit der Subduktion vor der südamerikanischenWestküste entstanden ist. Die Aktivität dieses Störungssystems reichte vom Eozän bis in das Quartär. Der Verlauf der West Fault ist im Untersuchungsgebiet (22° 04’ S, 68° 53’W) an der Oberfläche klar definiert und weist über viele zehner Kilometer eine konstante Streichrichtung auf. Die Aufschlussbedingungen und die Morphologie des Arbeitsgebietes sind ideal für kombinierte Untersuchungen der störungsbezogenen Deformation und der elektrischen Leitfähigkeit des Untergrundes mit Hilfe magnetotellurischer Experimente (MT) und der erdmagnetischen Tiefensondierung (GDS). Ziel der Untersuchungen war es, eine mögliche Korrelation der beiden Meßmethoden herauszuarbeiten, und die interne Störungsarchitektur der West Fault umfassend zu beschreiben.

Description: For the motivation behind our investigations, we refer to the introduction of the first part of our report, Hagedoorn & Geiner-Mai (2008). In this part, we will (i) give an analytical description of the topographic surface of the core-mantle boundary (CMB) and derive an approximation for its normal unit vector containing information about the CMB topography, and (ii) derive an expression for the topographic torque as a function of the topographic height, h, and the velocity field, u. For this, we will check the assumptions made when applying the geostrophic approximation to the upper core-surface region. Finally, we will derive analytical expressions for the torque components depending upon the spherical harmonic (SH) coefficients of h and u in a cartesian geocentric coordinate system.

Description: This volume contains extended abstracts from talks and posters presented at the sixth TRACE (Tree Rings in Archaeology, Climatology and Ecology) conference, held in Riga (Latvia) May 3rd – 6th, 2007.

Description: Based on the physical processes governing the motion and dynamics of poly-thermal ice sheets, we distinguish two regions; the cold region, where the ice temperature is below the melting point, and the temperate region, where the ice temperature is exactly equal to the melting point, leading to the presence of a water fraction. This work focuses on the analysis and description of the temperate zone on the basis of rational thermo-dynamics of reacting mixtures. The balance laws for the ice-water mixture, that is the mass balance, balance of linear and angular momenta, energy and entropy, are discussed. A physical model for a polythermal ice sheet is then established, including appropriate boundary and transition conditions. The resulting formulation is convenient for numerical implementation. Numerical examples are carried out for a stationary 2-D case and the results of the present and traditional formulations are compared.

Description: Bivergent wedges result from the interaction between deformation, flexure and surface processes. Based on 2D sandbox simulations in conjunction with PIV, this study investigates the influence of these processes on the spatio-temporal evolution of strain-partitioning within, and the associated surface uplift of, bivergent wedges. To facilitate interpretation and to successfully communicate results, two new display types, i.e., the surface uplift and the evolution of deformation map are introduced.

Description: This work describes the results of seismological field campaigns and experiments using combined seismic networks of varying geometries such as a combined seismic downhole and surface network or a combined temporary local and permanent regional network. The networks were deployed in different tectonic environments, i.e. in a stable intraplate surrounding, at a plate boundary along a major transform fault zone and in forearc and backarc settings of a subduction zone to record different types of seismicity (induced earthquakes, aftershocks, subduction-related seismicity). Recording periods are typically several months. The basic ideas behind all the different experiments and studies presented here can be described as follows: In a first step, a state of the art seismic network is designed and deployed in a selected area to record local (micro)seismic activity at low magnitude detection threshold. The acquired data base is then evaluated using standard processing techniques to generate a proper hypocenter catalog for the area of investigation during the observational period. This period might be extended (at higher magnitude detection threshold) through re-evaluating and calibrating earlier hypocenter catalogs gained from records of regional permanent networks. This new catalog for the selected region then forms the base for further evaluation using different approaches one of which is the determination of fault plane solutions in order to determine the local stress field orientation and relate it to the WSM data or information on regional displacement fields determined from GPS recordings.

Description: In this study two aspects of the geomagnetic field have been investigated. The first part focuses on perturbations of the external field, as seen by the CHAMP satellite and predicted by the Thermosphere-Ionosphere Electrodynamic General Circulation Model, for the purpose of helping to separate out ionospheric sources from the ambient geomagnetic field using a physics based approach. Part two looks at variations of the internal field through an examination of the South Atlantic Anomaly.

Description: This thesis presents investigations on sediments from two African lakes which have been recording changes in their surrounding environmental and climate conditions since more than 200,000 years. Focus of this work is the time of the last Glacial and the Holocene (the last ~100,000 years before present [in the following 100 kyr BP]). One important precondition for this kind of research is a good understanding of the present ecosystems in and around the lakes and of the sediment formation under modern climate conditions. Both studies therefore include investigations on the modern environment (including organisms, soils, rocks, lake water and sediments).

Description: The aim of this dissertation is to quantify scaling relations of strain accumulation in nature on various temporal and spatial scales, in order to characterize the underlying deformation mechanisms [...] Apart from the introduction (Chapter 1), the dissertation is divided into eight further chapters: a review of the common deformation frameworks, scaling relations and their dependence on parameter changes (Chapter 2); a description of the applied methods (Chapter 3); a description of the tectonic setting of the Central Andean plateau (Chapter 4); three scientifi c manuscripts for publication in international peer-reviewed journals (Chapter 5, 6, 7); additional analogue data (Chapter 8); and conclusions with outlook on future research (Chapter 9). The appendix includes all references used in any of the chapters, the deformation database used in Chapter 5, more geostatistical data, data for the sensitivity analysis, a short documentation on all performed granular experiments with set-up sketches, material properties of vise experiments, acknowledgments, and a CV.

Description: The objective of this study is to calculate the RSL height at the location of the Berkner Island ice core during the last glacial cycle using a viscoelastic earth model and several glacial histories. Earlier glacial cycles are not considered, the basic assumption being that the sediments were deposited during the last glacial cycle. However, to some extent the results can be extrapolated further back into the past. The results impose a constraint on the time of deposition of the sediments. Conversely, if the time of deposition is determined, e. g. by luminescence dating, this study provides a constraint on the glacial history of the Ronne Ice Shelf.

Description: The report describes the main results of investigations performed in 2001 year in framework of a research contract between GeoForschungsZentrum Potsdam (GFZ) and the Institute of Radio Engineering and Electronics of the Russian Academy of Sciences, Moscow (IRE).

Description: After a gap of nearly two decades since the Magsat mission in 1980, the dedicated low-orbit potential field mission CHAMP is now in the third of its seven year mission. Already, the new magnetic total intensity and vector data have yielded maps of the global crustal field of unprecedented accuracy and resolution. Here, we assess the value of these maps to infer deep crustal structure of regions overlain by younger cover. A GIS based modelling technique has been developed to model the various geological units of the continents starting from the geological map of the world. Depending upon the known rock types of the region, they are assigned a standard susceptibility value and using the global seismic crustal structure, a vertically integrated susceptibility (VIS) model is computed at each point of the region. Starting with this initial VIS model, the vertical field anomaly is computed at a satellite altitude of 400 km and compared with the corresponding CHAMP vertical field anomaly map. The first comparison is carried out against a model using the lateral extent of a cratonic region as given by published tectonic maps. In the subsequent modelling step, depending upon the extent of the observed anomaly pattern of that region, the surface geology is extended beneath the sediments until the recomputed map fits the observed magnetic anomaly map. Here, we focus on modelling results for the selected few provinces of the world where the initial model does not agree with the observed anomaly map. Similar modelling of CHAMP satellite magnetic anomalies can constrain the subsurface structure hidden by Phanerozoic cover in many parts of the world.

Description: Following work is embedded in the multidisciplinary study DESERT (DEad SEa Rift Transect) that has been carried out in the Middle East since the beginning of the year 2000. It focuses on the structure of the southern Dead Sea Transform (DST), the transform plate boundary between Africa (Sinai) and the Arabian microplate. In this work a short description of the seismic reflection method and the various processing steps is followed by a geological interpretation of the seismic data, taking into account relevant information from other studies.

Description: The Dead Sea Transform (DST) is a prominent shear zone in the Middle East. It separates the Arabian plate from the Sinai microplate and stretches from the Red Sea rift in the south via the Dead Sea to the Taurus-Zagros collision zone in the north. Formed in the Miocene »17 Ma ago and related to the breakup of the Afro-Arabian continent, the DST accommodates the left-lateral movement between the two plates. The study area is located in the Arava Valley between the Dead Sea and the Red Sea, centered across the Arava Fault (AF), which constitutes the major branch of the transform in this region. A set of seismic experiments comprising controlled sources, linear profiles across the fault, and specifically designed receiver arrays reveals the subsurface structure in the vicinity of the AF and of the fault zone itself down to about 3–4 km depth. A tomographically determined seismic P velocity model shows a pronounced velocity contrast near the fault with lower velocities on the western side than east of it. Additionally, S waves from local earthquakes provide an average P -to-S velocity ratio in the study area, and there are indications for a variations across the fault. High-resolution tomographic velocity sections and seismic reflection profiles confirm the surface trace of the AF, and observed features correlate well with fault-related geological observations. Coincident electrical resistivity sections from magnetotelluric measurements across the AF show a conductive layer west of the fault, resistive regions east of it, and a marked contrast near the trace of the AF, which seems to act as an impermeable barrier for fluid flow. The correlation of seismic velocities and electrical resistivities lead to a characterisation of subsurface lithologies from their physical properties. Whereas the western side of the fault is characterised by a layered structure, the eastern side is rather uniform. The vertical boundary between the western and the eastern units seems to be offset to the east of the AF surface trace. A modelling of fault-zone reflected waves indicates that the boundary between low and high velocities is possibly rather sharp but exhibits a rough surface on the length scale a few hundreds of metres. This gives rise to scattering of seismic waves at this boundary. The imaging (migration) method used is based on array beamforming and coherency analysis of P -to-P scattered seismic phases. Careful assessment of the resolution ensures reliable imaging results. The western low velocities correspond to the young sedimentary fill in the Arava Valley, and the high velocities in the east reflect mainly Precambrian igneous rocks. A 7 km long subvertical scattering zone (reflector) is offset about 1 km east of the AF surface trace and can be imaged from 1 km to about 4 km depth. The reflector marks the boundary between two lithological blocks juxtaposed most probably by displacement along the DST. This interpretation as a lithological boundary is supported by the combined seismic and magnetotelluric analysis. The boundary may be a strand of the AF, which is offset from the current, recently active surface trace. The total slip of the DST may be distributed spatially and in time over these two strands and possibly other faults in the area.

Description: Ein transversales Störungssystem im Nahen Osten, die Dead Sea Transform (DST), trennt die Arabische Platte von der Sinai-Mikroplatte und erstreckt sich von Süden nach Norden vom Extensionsgebiet im Roten Meer über das Tote Meer bis zur Taurus-Zagros Kollisionszone. Die sinistrale DST bildete sich im Miozän vor »17 Ma und steht mit dem Aufbrechen des Afro-Arabischen Kontinents in Verbindung. Das Untersuchungsgebiet liegt im Arava Tal zwischen Totem und Rotem Meer, mittig über der Arava Störung (Arava Fault, AF), die hier den Hauptast der DST bildet. Eine Reihe seismischer Experimente, aufgebaut aus künstlichen Quellen, linearen Profilen über die Störung und entsprechend entworfenen Empfänger-Arrays, zeigt die Untergrundstruktur in der Umgebung der AF und der Verwerfungszone selbst bis in eine Tiefe von 3–4 km. Ein tomographisch bestimmtes Modell der seismischen Geschwindigkeiten von P-Wellen zeigt einen starken Kontrast nahe der AF mit niedrigeren Geschwindigkeiten auf der westlichen Seite als im Osten. Scherwellen lokaler Erdbeben liefern ein mittleres P -zu-S Geschwindigkeitsverhältnis und es gibt Anzeichen für Änderungen über die Störung hinweg. Hoch aufgelöste tomographische Geschwindigkeitsmodelle bestätigen der Verlauf der AF und stimmen gut mit der Oberflächengeologie überein. Modelle des elektrischen Widerstands aus magnetotellurischen Messungen im selben Gebiet zeigen eine leitfähige Schicht westlich der AF, schlecht leitendes Material östlich davon und einen starken Kontrast nahe der AF, die den Fluss von Fluiden von einer Seite zur anderen zu verhindern scheint. Die Korrelation seismischer Geschwindigkeiten und elektrischer Widerstände erlaubt eine Charakterisierung verschiedener Lithologien im Untergrund aus deren physikalischen Eigenschaften. Die westliche Seite lässt sich durch eine geschichtete Struktur beschreiben, wogegen die östliche Seite eher einheitlich erscheint. Die senkrechte Grenze zwischen den westlichen Einheiten und der östlichen scheint gegenüber der Oberflächenausprägung der AF nach Osten verschoben zu sein. Eine Modellierung von seismischen Reflexionen an einer Störung deutet an, dass die Grenze zwischen niedrigen und hohen Geschwindigkeiten eher scharf ist, sich aber durch eine raue Oberfläche auf der Längenskala einiger hundert Meter auszeichnen kann, was die Streuung seismischer Wellen begünstigte. Das verwendete Abbildungsverfahren (Migrationsverfahren) für seismische Streukörper basiert auf Array Beamforming und der Kohärenzanalyse P -zu-P gestreuter seismischer Phasen. Eine sorgfältige Bestimmung der Auflösung sichert zuverlässige Abbildungsergebnisse. Die niedrigen Geschwindigkeiten im Westen entsprechen der jungen sedimentären Füllung im Arava Tal, und die hohen Geschwindigkeiten stehen mit den dortigen präkambrischen Magmatiten in Verbindung. Eine 7 km lange Zone seismischer Streuung (Reflektor) ist gegenüber der an der Oberfläche sichtbaren AF um 1 km nach Osten verschoben und lässt sich im Tiefenbereich von 1 km bis 4 km abbilden. Dieser Reflektor markiert die Grenze zwischen zwei lithologischen Blöcken, die vermutlich wegen des horizontalen Versatzes entlang der DST nebeneinander zu liegen kamen. Diese Interpretation als lithologische Grenze wird durch die gemeinsame Auswertung der seismischen und magnetotellurischen Modelle gestützt. Die Grenze ist möglicherweise ein Ast der AF, der versetzt gegenüber des heutigen, aktiven Asts verläuft. Der Gesamtversatz der DST könnte räumlich und zeitlich auf diese beiden Äste und möglicherweise auch auf andere Störungen in dem Gebiet verteilt sein.

Description: This thesis work describes a new experimental method for the determination of Mode II (shear) fracture toughness, KIIC, of rock and compares the outcome to results from Mode I (tensile) fracture toughness, KIC, testing using the International Society of Rock Mechanics (ISRM) Chevron-Bend (CB-) method. The fracture toughness describes the resistance of rock to fracturing. This parameter is therefore important when estimating the failure of rock and rock structures using rock fracture mechanics principles.

Description: The main objective of this thesis is an investigation and description of the secular variation of the Earth's magnetic field between 1980 and 2000. In particular, in the first part of this study the phenomenon of geomagnetic jerks are investigated by means of a deterministic model, which basically gives a description of the secular variation as a parameterization of typical periodicities of the external field. I argue that the conclusion drawn from this approach is not valid for explaining jerks as caused by external events and not valid to describe the global secular variation. In the second part a time--dependent model of the secular variation between 1980 and 2000 is developed. The endpoints of the time interval were chosen, because of the availability of high quality field models from satellite data for these epochs. The Gauss coefficients are expanded in time as function of cubic B--splines. This model is forced to fit field models from high quality vector measurements from MAGSAT in 1980 and OERSTED in 2000. The methodology is new. The model is a valuable extension of the hitherto existing time--dependent description of the secular variation, the GUFM which was valid until 1990. Unlike GUFM the model is based on observatory monthly means, and the knot spacing of the cubic B--Splines tighter than GUFM. Therefore it reveals a short term secular variation on subdecadal time scale, which was not as yet resolved. The model is also valuable to test the frozen flux hypothesis and to link some of the morphology of the radial field at the core--mantle boundary to the geodynamo. The third part of this thesis deals with the inversion of the time--dependent field and secular variation model for different kinds of core surface flow. These flows allow prediction of the decadal change of the length of the day, an observable which is independent to geomagnetic data. The prediction of some of the flows have the right tendency, but differ in slope from the observed change of the length of the day.

Description: The main objective of this study is the quantification and qualification of strain over a broad scale range, including its distribution, magnitude, and accumulation history during basin evolution. These objectives are important contributions to the questions of stress transfer and deformation processes in the Southern Permian Basin.

Description: [...] According to the results of this thesis the following mechanism is suggested to cause the cusp-related density anomaly: The energy input by the solar wind, as characterised by the merging electric field, provides the power for Joule heating of preferably neutral molecules. Soft particle precipitation in the cusp simultaneously enhances the altitude of maximal Pedersen conductivity, thus lifting up the heated layer in the cusp. The cusp-related density anomaly is then caused by local composition changes in the upper atmosphere due to the differential expansion of heavier particles. The density enhancement is more intensive during phases of high solar activity, i.e. a larger background density favours the formation of large anomalies. The atmospheric fountain in the cusp region affects the upper atmosphere globally. The harmonic exitation of the fountain in 2005 caused a global density variation of the thermosphere.

Description: Der vorliegende Bericht fasst die Ergebnisse der in den Jahren 2000 und 2001 durchgeführten Arbeiten zur Aufwältigung, zum primären Test- und Messprogramm sowie zum Monitoring in der Geothermiebohrung Groß Schönebeck 3/90 zusammen. Mit Mitteln aus der Grundfinanzierung des GeoForschungsZentrums Potsdam wurde die Bohrung aufgewältigt und bis in eine Endteufe von 4294 m vertieft. Sie erschließt geothermisch interessante Horizonte des Norddeutschen Beckens in Tiefen zwischen ca. 3900 m und 4300 m bei einem Temperaturniveau von ca. 150°C. Dabei gewonnene Ergebnisse lassen sich auf ähnliche geologische Randbedingungen im Norddeutschen Becken übertragen. Dieses Sedimentbecken zieht sich von den Niederlanden über Norddeutschland bis nach Polen hin.

Description: The dynamic oblateness of the Earth, in terms of the J2 or C20 coefficient of the Earth´s geo-potential has been derived by analysis of LAGEOS Satellite Laser Ranging (SLR) data. Although recent analyses of GRACE (Gravity Recovery and Climate Experiment) mission data of monthly C20 values since 2002 have shown high temporal correlations with LAGEOS results, significant differences still remain. As it is common practice in GRACE data processing to remove a priori the short-term nontidal atmospheric and oceanic induced variations of the gravity potential via the socalled Atmosphere and Ocean De-aliasing Level-1B (AOD1B) products, their use for LAGEOS data processing would allow a direct comparison of results and a rigorous combination of the solutions. Since the consideration of short-term non-tidal atmospheric and oceanic mass redistributions by means of AOD1B time series reveals a significant impact on LAGEOS data processing results, the AOD1B time series has been consistently prolongated back to the advent of LAGEOS-1 in 1976. An analysis for the period 1993-2006 leads to the major findings that the consideration of atmospheric and oceanic mass redistributions result in a considerably reduced seasonal signal in the LAGEOS C20 time series. This in turn reduces the correlation to GRACE significantly by about 30%. This is in opposite to what one would expect, i.e., a better agreement between GRACE and LAGEOS if common standards are applied. Thus, a LAGEOS solution corrected for short-term non-tidal atmosphere and ocean effects is much less sensitive to primarily annual hydrological mass variations than GRACE. In addition, significant semi-annual signals remain. Other indicators such as the unresolved bias between LAGEOS and GRACE in the order of 2·10-10 or LAGEOS orbits and Satellite Laser Ranging (SLR) observation residuals are hardly affected by the AOD1B model.

Description: Although the development of passive margins has been extensively studied over a number of decades, significant questions remain on how mantle and crustal dynamics interact to generate the observed margin geometries. Here, the Orange Basin, located on the south-west African continental margin is investigated. The basin fill is considered to comprise a classic rift-drift passive margin sequence recording the break-up of Gondwana and subsequent opening of the South Atlantic Ocean. Based on interpreted seismic reflection data, a 3D geological model was first constructed. Subsequently, an isostatic calculation (Airy´s model) using a homogeneous middle and lower crust was applied to this geological model to determine the position of the Moho for an isostatically balanced system. Isostatic sensitivity tests were applied to the model, and their gravity response was validated against different crustal structures for the basin. The best-fit model requires dense, presumably mafic material in the middle and lower crust beneath the basin and an abrupt change to less dense material near the coast to reproduce the observed gravity field. The passive margin of the South Atlantic shows typical features of a rifted volcanic continental margin, encompassing seaward dipping reflectors, continental flood basalts and high-velocity/density lower crust at the continent-ocean transition, probably emplaced during initial seafloor spreading in the Early Cretaceous. The Springbok profile offshore western South Africa is a combined transect of reflection and refraction seismic data. This thesis addresses the analysis of the seismic velocity structure in combination with gravity modelling and isostatic modelling to unravel the crustal structure of the passive continental margin from different perspectives. The velocity modelling revealed a segmentation of the margin into three distinct parts of continental, transitional and oceanic crust. As observed at many volcanic margins, the lower crust is characterised by a zone of high velocities with up to 7.4 km/s. The conjunction with gravity modelling affirms the existence of this body and at the same time substantiated its high densities, found to be 3100 kg/m³. Both approaches identified the body to have a thickness of about 10 km. Yet, the gravity modelling predicted the transition between the high-density body towards less dense material farther west than initially anticipated from velocity modelling and confirmed this density gradient to be a prerequisite to reproduce the observed gravity signal. Finally, isostatic modelling was applied to predict average crustal densities if the margin was isostatically balanced. The results imply isostatic equilibrium over large parts of the profile; smaller deviations are supposed to be compensated regionally. The calculated load distribution along the profile implies that all pressures are hydrostatic beneath a depth of 45 km. The presence of lower crustal bodies of high seismic velocities indicates that large volumes of igneous crust formed as a consequence of lithospheric extension. Furthermore, results of a combined approach using subsidence analysis and basin history inversion models are presented. The outcome shows that a classical uniform stretching model does not account for the observed tectonic subsidence. Moreover, it is found that that the thermal and subsidence implications of underplating need to be considered. Another departure from the uniform stretching model is renewed sub-crustal stretching and linked to that uplift in the Cenozoic which is necessary to reproduce the observed phases of erosion and the present-day depth of the basin. The dimension of these events has been examined and quantified in terms of tectonic uplift and sub-crustal stretching. Based on these forward models the heat flow evolution is predicted not only for the available real wells but also for virtual wells over the entire study area. Finally, the hydrocarbon potential and the temperature evolution is presented and shown in combination with inferred maturation of the sediments for depth intervals which comprise potential source rocks.

Description: One significant outcome of my thesis is an improved chronostraphigraphical framework for the glacial lacustrine unit of the Black Sea sediment cores, which allowed to refine the environmental history of the Black Sea region and enabled a reliable correlation with data from other marine and terrestrial archives. Data gathered along a N-S transect presented on a common time scale revealed coherent changes in the basin and its surrounding. [...] My PhD thesis is based on four manuscripts, published or submitted to peer-reviewed international journals, and one additional preliminary study.

Description: This study focuses on tectonics at the Neogene and late Quaternary time scales in the Main Cordillera and coastal forearc of the south-central Andes. For both domains I document the existence of previously unrecognized active faults and present estimates of deformation rates and fault kinematics. Furthermore these data are correlated to address fundamental mountain building processes like strain partitioning and largescale segmentation.

Description: This thesis aims to understand these changes and reasons behind by analyzing the styles of deformation of the western margin of South America, in particular the surface expression of deformation, along the Chilean convergent margin. To understand the parameters controlling the style of deformation in the chosen areas I applied 3D transient numerical modeling. This thesis represents the first real 3D study analyzing deformation caused by oblique convergence associated with a realistic composite rheology.

Description: The Central European Basin System is one of the basins where the sedimentary cover is strongly affected by salt tectonics. The most significant stage of salt movement occurred during the Triassic. The largest Triassic subsidence occurred in the different sub-basins surrounding the Ringkoebing-Fyn High such as the Horn Graben, the Danish Basin and the Glueckstadt Graben. Furthermore, the thickest Triassic succession is observed in the Glueckstadt Graben where it reaches more than 9000 m. In the present study, the structure and the Permian to recent evolution of the Glueckstadt Graben are investigated by use of borehole data, seismic lines and 3D structural modelling. The evaluation of the diverse deformation patterns of the sedimentary cover and their relations to salt structures show that the strongest salt movements occurred at the beginning of the Keuper when the Gluckstadt Graben was affected by extension. The onlap patterns of the Jurassic sediments onto the top of the Keuper succession indicate essential changes of the sedimentation style during the Jurassic. Thick Jurassic sediments are only observed around salt structures and are thinning away from salt walls or salt stocks. The Upper Cretaceous strata have an approximately constant thickness and the parallel reflections patterns indicate a quiet tectonic setting with very minor salt movements in the Late Cretaceous. Renewed salt flow during the Paleogene-Neogene caused rapid subsidence along the marginal parts of the Central Triassic Graben in the Westholstein, the Eastholstein and the Hamburger troughs. The thick Paleogene-Neogene strata within the marginal troughs may also be related to a regional component of tectonic subsidence in the area, contemporary with rapid subsidence in the North Sea. The 3D modelling approach has been used to determine salt distribution at certain paleo-levels in response to unloading due to sequential removing of the stratigraphic layers. The modelling approach was also aimed to reconstruct the original Permian salt distribution immediately after deposition. The initial salt thickness varies from 1300 m at the flanks of the basin up to 3000 m within the central part and demonstrates a clear NNE-SSW trend of the basin. The regional trend of the restored salt distribution points to a westward continuation of the Permian salt basin. The formation of the deep Central Triassic Graben and the subsequent Jurassic- Cenozoic marginal troughs was strongly controlled by the development of salt structures through time. It is shown that the depocentre of sedimentation was moving away from the central part of the of the original Graben structure towards its margins. The evaluation of the available data and results of the 3D reverse modelling demonstrate that a greater amount of subsidence occurred close to the active salt structures, and may have resulted in gradual depletion of Permian salt. Thus, this study indicates that the source of such long-term subsidence is derived from gradual depletion of the Permian salt, which started within the axial part of the basin and moved towards the basin flanks with time. In this sense, the Glueckstadt Graben was formed at least partially as a “basin-scale rim syncline” during post-Permian times. Therefore, the results show that salt withdrawal may have played an important role during the Meso-Cenozoic evolution and that the effects of salt-driven subsidence during the Meso-Cenozoic can be considered the main reason for the formation of the deep Central Triassic Graben and the subsequent Jurassic-Cenozoic marginal troughs.

Description: Das zentraleuropäische Beckensystem ist eines der Becken, in denen die Sedimentdecken stark durch Salztektonik beeinflusst sind. Die stärksten salztektonischen Aktivitäten traten während der Trias auf. Die größte triassische Subsidenz erfolgte in den verschiedenen Unterbecken rund um das Ringköbing-Fünen Hoch (Horn Graben, Dänisches Becken, Glückstadt Graben). Die mächtigste triassische Abfolge wurde im Glückstadtgraben beobachtet, wo sie mehr als 9000 m Mächtigkeit erreicht. In der vorliegenden Studie wurden die Struktur sowie die Entwicklung des Glückstadt Grabens vom Perm bis heute mit Hilfe von Bohrdaten, seismischen Linien und 3D-Strukturmodellierung untersucht. Die Auswertung der verschiedenen Deformationsmuster der Sedimentdecke und ihr Bezug zu Salzstrukturen zeigen, dass die stärksten Salzbewegungen am Beginn des Keupers, während einer Dehnung des Glückstadt Graben auftraten. Die jurassischen Sedimente zeigen dann eine grundlegende Änderungen der Sedimentationsart während des Jura an. Mächtige jurassische Sedimente treten nur rund um Salzstrukturen auf und dünnen mit zunehmender Entfernung von Salzmauern oder Salzstöcken aus. Die Oberkreideschichten haben eine annähernd konstante Mächtigkeit, und die parallelen Reflektionsmuster weisen auf eine ruhige tektonische Subsidenz mit geringen Salzbewegungen in der Oberkreide hin. Erneute Salzbewegungen während des Paläogens-Neogens verursachten schnelle Subsidenz entlang der Randbereiche des zentraltriassischen Grabens, den Westholstein, Ostholstein und Hamburger Trögen. Die mächtigen paläogen-neogenen Schichten innerhalb der Randtröge sind eventuell auch mit einer regionalen Komponente tektonischer Subsidenz verbunden, zeitgleich mit schneller Subsidenz in der Nordsee. Der 3D- Modellierungsansatz wurde genutzt, um die Salzverteilung für verschiedenen Paläolevels als Reaktion auf Entlastung durch sequentielles Entfernen der stratigraphischen Schichten zu bestimmen. Mit dem Modellierungsansatz wurde auch versucht, die ursprüngliche permische Salzverteilung unmittelbar nach der Ablagerung zu rekonstruieren. Die ursprüngliche Salzmächtigkeit variiert zwischen 1300 m an den Beckenflanken und bis zu 3000 m innerhalb des zentralen Teils und zeigt einen klaren NNO-SSW-Trend innerhalb des Beckens. Die Bildung des tiefen zentraltriassischen Grabens und der nachfolgenden jurassisch- känozoischen Randtröge wurde stark durch die langandauernde Entwicklung von Salzstrukturen kontrolliert. Es wird gezeigt, dass das Sedimentationszentrum sich vom Zentralteil der ursprünglichen Grabenstruktur in Richtung ihrer Ränder verlagerte. Die Auswertung der verfügbaren Daten und die Ergebnisse der 3D-Rückwärtsmodellierung zeigen, dass der größte Teil der Subsidenz nahe aktiver Salzstrukturen auftrat, und eventuell zu einer graduellen Abwanderung permischer Salze führte. Daher zeigt die Studie, dass die Ursache der langzeitigen Subsidenz die graduelle Abwanderung permischen Salzes ist, welche im axialen Teil des Beckens begann und sich im Laufe der Zeit in Richtung der Beckenflanken bewegte. In diesem Sinne wurde der Glückstadtgraben zumindest teilweise in nachpermischer Zeit als basin-scale rim syncline geformt. Daher zeigen die Ergebnisse, dass dieser Salzrückzug während der meso-känozoischen Evolution eine bedeutende Rolle gespielt haben dürfte, und dass die Effekte salzgesteuerter Subsidenz während des Meso-Känozoikums als Hauptursache der Bildung des tiefen zentraltriassischen Grabens und die nachfolgenden jurasso- känozoischen Tröge angesehen werden kann.

Description: This volume contains the results of the DESERT project running from 2000 to 2006. It opens with a review paper (DESERT Group, 2009) followed by 33 special papers, see list of content (529 pages).

Description: This study is aimed at a development of numerical method to model the dynamic geoid and the surface plate velocities induced by global mantle flow with the effect of strong lateral viscosity variations (LVV) in conjunction with the effects of selfgravitation and mantle compressibility. I employ the technique, which comprises the combination of the spherical harmonic method, the direct Godunov method used for solving the Stokes and Poisson equations in spherical harmonics with arbitrary boundary conditions, functions of density and radial viscosity, and the iterative method based on the principles suggested by Zhang and Christensen (1993) used for modeling the effect of LVV. The 3-D mantle viscosity model is based on the global seismic tomography model S20a converted to temperature variations. The maximum lateral viscosity contrast in the lithosphere-asthenosphere zone modeled reaches four orders of magnitude. It is found that the influence of LVV on the dynamic geoid is extremely significant: an alteration of the geoid figure due to LVV exceeds 45% of the maximum geoid undulations. The detailed analysis showed that the geoid is affected by both, strong LVV induced in the upper mantle and large-scale LVV induced in the lower mantle. According to the results of this study the separated effects of the upper- and lower-mantle LVV on the geoid figure are nearly additive with respect to the whole-mantle LVV and partly compensating with respect to each other. The mantle flows are strongly affected by LVV as well, especially by the long-wavelength viscosity variations in the lower mantle: global upwellings tend to intensify due to the effects of LVV, while downwellings become weaker. The alteration of the near-surface velocities reaches 30-40% in amplitude not only due to the LVV induced toroidal flow but also due to change in the spheroidal velocity component. I can conclude that the LVV presented in both, upper and lower mantle, play an important part in global modeling, therefore, an incorporation of 3-D viscosity structure into the next generation global dynamic models is a task of vital significance.

Description: A set of 59 seismological stations was deployed in the Central Andes region at 21°S (Chile-Bolivia) along a profile ~600 km long and were operated between 2002 and 2004. The teleseismic tomographic images (from P- and S- waves) show low-velocity anomalies that are interpreted as the effects of melting or fluids at both flanks of the Altiplano plateau. Beneath the Central Volcanic Zone (CVZ) a low-velocity anomaly is interpreted to be caused by fluids that are the origin of the volcanic material from the CVZ. A low-velocity anomaly in the upper crust is interpreted as the Altiplano Low-Velocity Zone that appears to extend as far to the east as the Eastern Cordillera. A high-velocity body between 100 km and 150 km depth is interpreted as being part of the old cold lithosphere that detached from the base of the crust. The Brazilian Shield is thought to be responsible for the strong high-velocity anomaly on the eastern side of the Central Andes. In addition, another set of 19 stations was deployed in the southern Argentine Puna along a profile ~200 km long and were run over the same period of time (2002-2004). The intention was to study the crustal thickness at 25.5°S, where delamination of the lithosphere was proposed to explain the higher elevation of the Puna plateau. Beneath the plateau a negative velocity anomaly is observed and interpreted here as being the location of fluid transfer between the deeper and shallower portions of the crust, that emanate from the Benioff zone at depths of ~200 km. This anomaly clearly divides in two branches: one to the west towards the volcanic arc (CVZ) and the other to the east where the back-arc volcanoes are located. On their way to lower depths, the fluid paths are probably influenced by the presence of nearby isotherms. The bifurcation of the ascending path could be related to the presence of the lithosphere-asthenosphere boundary (LAB) at ~100-130 km. Based on our observations, the type and form of the anomaly, it is possible to propose the presence of a return-flow type model for fluid ascent in contraposition to the assumed corner-flow model usually proposed for the Andes. The fluids that cause the seismic anomalies beneath the Puna plateau are generated at deeper levels in the asthenosphere and ascend parallel to the oceanic slab in the manner of a return-flow. In the crust and beneath the Salar de Antofalla (SA), a high-velocity block with seismic activity is interpreted as part of the old and cold Palaeozoic magmatic arc (Faja Eruptiva de la Puna Occidental). The presence of this block is may be responsible for the distribution of volcanic activity localized at both sides of this anomaly. Eastern of the SA, it is possible to recognize a zone with low-velocities beneath the Galan volcano. A sharp limit imposed by high velocities, probably related to metamorphic rocks from the Paleozoic basement (Tacuil and Luracatao ranges) can be detected on the east of the profile. A high-velocity block with seismic activity is located in the crust beneath the Salar de Antofalla (SA) and interpreted as part of the old and cold Palaeozoic magmatic arc (Faja Eruptiva de la Puna Occidental). This block might be responsible for the distribution of volcanic activity localized at both sides of this anomaly. Beneath the Galan volcano and east of the SA, a zone with low-velocities can be recognized. A sharp limit towards high-velocities can be observed on the east of the profile, probably related to metamorphic rocks from the Palaeozoic basement (Tacuil and Luracatao ranges).

Description: The joint project TIPTEQ (from The Incoming Plate to mega-Thrust EarthQake processes) refers to an integrated approach in order to investigate the processes active in the seismogenic coupling zone at the southern Central Chilean margin and to validate their importance for both the initiation of mega-thrust earthquakes and the evolution of the forearc. The lateral variability of these processes and related parameters is investigated along five marine corridors offshore the south Chilean continental margin. The northernmost marine transect is continued onshore with a reflection seismic survey at 38.2◦ S which crosses the hypocenter of the largest ever recorded earthquake, the 1960 Great Chilean earthquake (Mw = 9.5). The processing and structural interpretation of this high-resolution seismic data set is one major task of this thesis. Furthermore, a first-break tomography was conducted to construct a near-surface velocity model. Several tests to validate the tomographic images were conducted and the limitations of the data set and method were explored in detail. The reflection seismic transect lies in the center of an extensive geophysical program comprising magnetotelluric surveys and a large seismological network. An integrative interpretation with the results of the other geophysical groups of TIPTEQ concludes the thesis. The depth section of the TIPTEQ NVR data set shows the subducting Nasca plate below the segmented forearc and a highly reflective overriding South American plate down to a depth of 60 km. High reflectivity directly above the plate interface suggested to be associated with the existence of a subduction channel with a varying thickness of 2 - 5 km down to a depth of at least 38 km. It might continue towards depth. Local seismicity possibly defines the upper bound of the subduction channel. The continental Moho is not clearly imaged. However, one possible location is at 38 - 40 km depth given by the 1960 earthquake hypocenter. The Moho may be continued eastwards to a depth of 35 km where a prominent structure is imaged. This reflector coincides with the modeled Moho interface from a 3–D density model along the Chilean margin. The reflectivity east and above of the 1960 hypocenter area may exhibit alternative eastward continuations of the continental Moho. The position and extent of the continental mantle wedge changes accordingly. Major forearc features such as the crustal Lanalhue Fault Zone and a strong west-dipping reflector perpendicular to the plate interface can be observed. The reflectivity of the oceanic crust increases in depths below 35 km. This increase might be caused by fluid release due to the porosity collapse in basalt. The integrative interpretation links this observation with a zone of high Vp/Vs ratio calculated from the seismological velocity model. Combining all available data sets of seismological, magnetotelluric and gravimetrical findings results in a complex image of the southern Chilean subduction zone, which this thesis addresses to decode.

Description: [...] Studies regarding the theory of this correlation and how to handle it when estimating sub-daily polar motion together with nutation are included in the thesis. Furthermore, it is demonstrated that the common estimation of the terrestrial reference frame and EOPs can be employed to identify a mismatch between the local tie values and the estimated coordinate differences at co-located sites. Thus, the EOPs offer another independent evaluation of the LT values, as mentioned already above for the troposphere gradients. For the studies described in this thesis, it is of vital importance that continuous observations are available for all observation techniques. Therefore, the so-called CONT campaigns of the International VLBI Service for Geodesy and Astrometry (IVS) are well-suited. Such special campaigns with continuous VLBI observations for several days are initiated from time to time in order to demonstrate the full capabilities of VLBI. The studies described in the thesis at hand are based on the two-week CONT campaign scheduled in October 2002, named CONT02.

Description: A Databank was created using data from 25 local catalogues and 30 special studies of earthquakes in central, northern and northwestern Europe. Event types were discriminated, fake events and duplets eliminated, and different magnitudes and intensities converted to Mw. The conversions require the establishment of regression equations. The Catalogue contains tectonic events from the Databank within the area 44°N-72°N, 25°W-32°E and the time period 1300-1993 which have Mw magnitudes of 3.50 and larger. The area is covered by different polygons. Within each polygon only data from one or a small number of the local catalogues, supplemented by data from special studies, enter the Catalogue. If there are two or more such catalogues or studies providing a solution for an event, a priority algorithm selects one entry for the Catalogue. Then Mw is calculated from one of the magnitude types, or from macroseismic data, given by the selected entry according to another priority scheme. The origin time, location, Mw magnitude and reference are specified for each entry of the Catalogue. So is the epicentral intensity, I0, if provided by the original source. Following these criteria, a total of about 5,000 earthquakes constitute the Catalogue. Although originally derived for the purpose of seismic hazard calculation within GSHAP, the Catalogue provides a data base for many types of seismicity and seismic hazard studies.

Description: As part of this thesis, a new strategy for the inversion of stress states from fault-slip data is introduced (Chapter 2). This new approach is applied to data sampled from outcrops along the southern margin of the CEBS (Chapter 4) and from outcrops in the Oslo Graben area (Chapter 5). The results derived from these study areas deliver new insights into the evolution of paleostress fields that controlled the development of the entire CEBS.

Description: This study presents methods and field experiments for ground-based GPS altimetry. Although Coarse/Acquisition Code (C/A-code) based methods are introduced, the main part of this work addresses the use of carrier phase-delay observations of the reflected GPS signal and focuses on specular reflection. [...] This study approves the feasibility of ground-based GPS altimetry with the OpenGPS receiver and with only one low-gain and wide field-of-view RHCP antenna using L1 carrier phase-delay observations of reflected GPS signals. The work shows the potential of GPS reflectometry for remote water level monitoring from a safe position in cases where in-situ measurements are not possible, are dangerous or sensors may get destroyed by the highly dynamic sea or glacier environment.

Description: As a technical memorandum for the TIGA/SEAL project, this report describes the procedure and scheme of GPS data processing and product provision at GFZ for monitoring the vertical motion at tide gauge benchmarks to study the global eustatic sea level change. As one of the TIGA analysis centers (TAC), GFZ is processing data from about 370 GPS stations in three lines: backward reprocessing till 1994, forward processing with 66-week latency and one-week delay processing in parallel with IGS as part of IGS activities. The quality of the station coordinate solutions is assessed by comparing with o±cial IGS combination solutions and other TACs' solutions. The consistency with IGS solutions is 4 - 1 mm in the horizontal components, and 8 - 4 mm in the height component, improving with time. The larger discrepancy in earlier time indicates the improvement of TIGA reprocessing. The consistencies with other TACs are not as good as that with IGS. This may come from twofold effects. On the one hand, GFZ TIGA solutions also contribute to IGS. So, the IGS combination solutions should be internally consistent with GFZ TIGA solutions to a certain extent. On the other hand, the differences on software package, strategy and the size of network may also cause a worse consistency among each other. However, the combination of various TACs' solutions gives feedback to improve the single contribution and by this the final products.

Description: In this report we describe the new repeat station network, the measurements and some tests regarding the use of the variometer recordings for data processing, and we present the results of this latest German magnetic survey.

Description: Recently released global gravity field models generated solely from CHAMP and GRACE satellite observations allow with an unprecedented accuracy and resolution the recovery of the mean sea surface topography from the difference between an altimetry-based mean sea surface height model and the gravity model's derived geoid. Here the CHAMP EIGEN-2 gravity field model, and the first GFZ GRACE gravity model, EIGEN-GRACE01S, are used. The mean sea surface height model has been compiled from four years'; worth of TOPEX altimeter data. To evaluate the accuracy and resolution limits of the CHAMP and GRACE geoids for the envisaged application, a low pass filter in the spatial domain with different cut-off wavelengths has been applied to the geoid and sea surface data before subtraction. The minimum wavelength, where noisy and erroneous features in the recovered sea surface topography are minimised, can be interpreted as an indicator for the best suited common spatial resolution. The EIGEN-2 model's geoid has been tested to have a resolution of 1800 km, which corresponds to a truncation degree of l = 22 in terms of spherical harmonics. Using the EIGEN-GRACE01S model, the resolution could be extended to 1000 km (l = 40). These boundaries can be attributed to the geoid's error, exceeding 2 cm in case of the CHAMP model, and in case of the GRACE model to spurious systematic signals increasing with increasing spherical harmonic degree. The calculated sea surface topography models have been used to derive absolute geostrophic sea surface velocities. An error propagation shows that the requirement of 1 cm/s for geoid induced velocity errors is fulfilled at the given resolutions for all latitudes excluding a narrow equatorial band. Maximum geostrophic velocities are derived in the 1000 km-resolution model for the Kuroshio region with 40 cm/s, and for the Gulf Stream east off Cape Hatteras with 25 cm/s.

Description: The report contains a description of main results obtained within the research contract between IRE RAS and GFZ Potsdam and results of investigation during period November-December 2007 – the third stage of the contract. The objectives of investigation included (1) elaboration and verification of an innovative phase acceleration-refraction attenuation technique to locate layered and wave structures in the ionosphere and atmosphere; (2) elaborating of a new technique for identification of wave origin of temperature and density fluctuations and determination of the intrinsic frequency of internal gravity waves in the Earth's stratosphere from radio occultation (RO) data; presentation of a technique for evaluating the vertical profiles of the phase, amplitude, horizontal wind perturbations, intrinsic phase speed, kinetic and potential energy of atmospheric waves; (3) maps of waves parameters in the ionosphere and atmosphere showing their regional, seasonal and diurnal variations with aim to establish connections with solar and meteorological activity.

Description: Polar motion data is available from the mid-19th century to the present. Based on time series with a variety of sampling intervals (monthly, 0.05-year, 5-day and daily), we have separated the low-frequency terms by low-pass filtering and the Chandler and annual terms by recursive band-pass filtering of the pole coordinates. Using a simple unweighted least-squares fit to the filtered low-frequency terms, the linear trends of the rotation pole were estimated. Assessing the estimates based on intercomparisons, the most reliable trend estimate was found. Using a Fast Fourier Transform, we have computed the prograde, retrograde and total amplitude spectra of the low-frequency part of polar motion in order to reveal the long-periodic signals. The characteristics and time evolution of the Chandler and annual wobbles are described by changes in their parameters (radii, directions and period lengths) over one century.

Description: This report describes the set-up, logistics and results of the CHICAGO (Chilean Coastal AeroGeophysical Observations) survey. It gives a short overview about the scientific intentions, detailed documentation of all technical aspects starting from the survey equipment via the aircraft installation to the GPS stations set-up and the experiences in flight. All processing results for the individual profiles are discussed in detail. Finally, the data is compared and combined with available recent marine gravity data and altimetry derived solutions.

Description: This report studies the vertical crustal motion at tide gauges by analyzing GPS (Global Positioning System) height time series of about 370 GPS stations spanning 1994.0 to 2007.0. The procedure of generating a set of homogeneous GPS time series is described in detail. To estimate the vertical rate, the time series are modelled with seasonal (annual and semiannual) waves and step functions for jumps. To improve the quality of the time series, the ocean tide loading (OTL) corrections are renovated by replacing the OTL corrections derived from new ocean tides model directly on the solutions without re-analyzing the GPS data.

Description: The LaCoste & Romberg gravity meter S124b and its associated system environment were installed and tested in conjunction with a strap-down gravity meter system (SAGS) of the Bayerische Akademie der Wissenschaften in Munich on a Cessna Grand Caravan of the DLR in Oberpfaffenhofen. This report describes the design and instrumentation of the aerogravimetry system, it documents the installation on the aircraft and it discusses some of the results of the test flights performed within AGFA (Airborne Gravity Flight Approach). Beyond the documentation of the system this report gives a short introduction to the basics of the instruments including a short theory of their operation and data processing. The intention is to give readers from disciplines other than aero-gravimetry and aero-altimetry a technical insight into how the system works and what it is capable of. This should help the reader to evaluate the systems usefulness in other geo-scientific projects. The experiences from the test flights are briefly summarized and an update of the current status and future plans for the individual instruments is given. The aerogravimetry system consists of two major instrument blocks: the gravimetry sensing system and the positioning system. The gravimetry sensors are the LaCoste & Romberg S124b and the SAGS-2.2 systems. The navigation block holds GPS receivers, an inertial navigation system and a laser altimeter. The aircraft used for the primary tests was a Cessna Grand Caravan of the DLR in Oberpfaffenhofen. It offers superb conditions for scientific installations and is widely used in geophysical exploration all over the world. The test flights were flown from Oberpfaffenhofen airport. One profile covers the Bavarian Alps to map short wavelength, topography induced gravity disturbances, and another flight crosses the Rhine Graben to map long wavelength structures of the deeper crust. The software for data processing for navigation, gravimetry and geoid calculations is briefly summarized.

Description: This study attemps to identify and quantify the parameters that control mass-transfer modes in brittle tectonically erosive and accretive forearc settings. Scaled analogue simulations, which are specifically designed for this task, are compared with the convergent Chilean Margin that demonstrates both of these mass-transfer modes. Analogue simulation of geodynamic processes requires granular materials (e. g. sand) that deforms similarly to typical crustal rocks. Accordingly, a parameter study is performed, which yields general insight in the basic mechanics of highly-idealised convergent sand wedges.

Description: Compared to the Chandler and annual wobbles, the higher-frequency components of polar motion (PM) have substantially smaller amplitudes. Therefore, their study had to wait until higher-quality time series with high temporal resolution, as measured by space geodetic techniques, became available. Based on the combined Earth orientation series SPACE99 computed by the Jet Propulsion Laboratory (JPL) from 1976 to 2000 at daily intervals, we have separated the periodic PM terms by band-pass filtering and found that the persistence of oscillations becomes less with increasing frequency (H¨opfner 2001a, b). In order to quantify and better describe the parameter variability of these PM components over time, particularly of eight oscillations with periods ranging between about 650 and 45 days, we computed the radii, direction angles and period lengths from the periodic terms filtered out from the time series. The results clearly show the characteristics and time evolution of the periodic PM components that are important for geophysical interpretations.

Description: The Effect of the Geocentric Gravitational Constant on Scale: It is well known that the geocentric gravitational constant (GM) is a scaling factor for the reference frame realized by satellite techniques. One must be aware that its effects on the orbit and on the terrestrial reference frame (station positions) are different. The scale effect on restituted orbits is 1/3* (dGM/GM) (relative error of GM) for all kinds of satellites. But the effect on the terrestrial frame depends on the height of the satellites, on tracking techniques and on the solved for parameters. For ranging techniques such as SLR, the scale variation of the terrestrial frame is 1/3*(dGM/GM)*(rSat) / (rEarth), if the range biases are not solved for. For GPS the GM error is mostly absorbed by the clock estimates (or eliminated by the double differences), only the remaining few percents go into the scale of terrestrial reference frame. For instance if one is using a GM value of 3.986004418 1014 m3/s2 instead of 3.986004415 1014 m3/s2 (relative variation is 7.5 10-10) the scale variation of the terrestrial frame is only about 6 10-11. Physically, the error in the z-direction of the antenna phase center offsets on board GPS has nothing to do with GM. But its effect on the terrestrial reference frame is practically equivalent to an error in GM. For instance, if all GPS satellites have a 7.1 cm error in dz, the effect on the station position is equivalent to a relative error of 8 10-9 in GM (e.g. changing GM from 3.986004418 to 3.986004386 1014 m3/s2). Satellite Antenna Phase Center Offsets and Scale Errors in GPS Solutions: ITRF2000 solutions (see Lareg, 2001) have shown that there are ppb level scale differences between GPS and other techniques and among various GPS Analysis Centers. The trends of the scale differences reach 0.2 ppb per year. The uncertainties of the current available Earth’s gravitational constant could only cause less than 0.1 ppb scale error for GPS technique. On the other hand, the uncertainties in the satellite antenna phase center offsets could produce ppb level scale error. Various BLOCK types of GPS satellites have different phase center errors. The number of BLOCK IIR satellites increases from year to year. This could cause trend-like variations in the scale error. Beside station positions, satellite antenna phase center errors affect also the clock, Zenith Path Delay, and other solved for parameters perceptibly.

Description: The here presented study contributes to the understanding of convergent plate boundaries in the depth range of their former seismogenic zone aiming at testing inferences and hypotheses of the various kinematic and mechanical concepts presented for the seismogenic zone. Therefore, we use the complete exposure of this part of a former plate interface in the European Alps, one of the best-studied mountain belts that has resulted from successive subduction, accretion and collision, where we analyzed a mélange zone tracing the plate interface zone of the fossil convergent plate margin. Additionally, we included information from Southern Chile, where material, which formerly underwent deformation along the plate interface, was exhumed to the surface by large scale basal accretion at a certain depth to the base of the upper plate. This part of the study provided additive hints for structures and processes occurring along the plate interface zone of convergent plate margins (i.e. within the subduction channel), at least for a restricted PT domain.

Description: Chandler and annual wobbles based on space-geodetic measurements: In this study, we examine the major components of polar motion, focusing on quantifying their temporal variability. In particular, by using the combined Earth orientation series SPACE99 computed by the Jet Propulsion Laboratory (JPL) from 1976 to 2000 at daily intervals, the Chandler and annual wobbles are separated by recursive band-pass filtering of the χ1- and χ2 -components. Then, for the trigonometric, exponential, and elliptic forms of representation, the parameters including their uncertainties are computed at epochs using quarterly sampling. The characteristics and temporal evolution of the wobbles are presented, as well as a summary of estimates of different parameters for four epochs.

Description: Polar motions with a half-Chandler period and less in their temporal variability: Our study focuses on the observed higher-frequency polar motions that are substantially smaller than the Chandler and annual wobbles. Here, the combined Earth orientation series SPACE99 from 1976 to 2000 with one-day sampling is used as input data, after removing the low-frequency, the Chandler and annual terms. We applied a data processing procedure including four steps, each computing the amplitude spectrum by a Fast Fourier Transform in order to reveal the periodic signals in the residual motions, and then separating their components from the residual time series by band-pass filtering. In particular, the oscillations have the following periods: Semi-Chandler and semi-annual periods and those of order four, three, two, and one and a half months, as well as quasi-biennial and 300-day periods. We show to what extent the observed polar motions are irregularly occurring. A very small polar motion signal with the period of one month is still found in the remaining motions.

Description: The Altiplano represents a key region of the Central Andes, where the interplay between faults and syn-tectonic sediments allow the reconstruction of the kinematic evolution of the Central Andean high plateau. This study aims, by the use of incrementally-balanced crosssections, interpretation of reflection-seismic profiles, 3D strain analysis, gravity data interpretation, isotopic-age dating, and surface observations, to reconstruct the geological and tectonic history of the Southern Altiplano at 21o S between the Eastern and the Western Cordillera. The Southern Altiplano is a complex intramontane basin with 6-8km Cenozoic fill. It can be structurally divided in three domains; the Eastern, Central, and Western Altiplano. 2D balanced cross-sections based on seismic-reflector analysis and field observations show that the Eastern Altiplano is the buried, thin-skinned deformation front of the western part of the Eastern Cordillera's bivergent thrust system. The 20-40° dipping, blind faults merge into a shallow, eastward-dipping detachment at 7-9km depth that continues into the Eastern Cordillera. The Central Altiplano forms a bivergent system with 30-90° dipping, basement-involving thrusts in the east, and fault-propagation folds in the west. The shallow, westward-dipping detachment lies at 9-10km depth and possibly continues into the Western Altiplano, which forms a separate bivergent thrust-system.The computer-aided (GeoSec and 2DMove), incremental restoration of the balanced crosssections of the Eastern and Central Altiplano, and preliminary line-length balancing of the Western Altiplano, yields 38km shortening due to folding and thrusting. 3D strain analysis of sandstone grain shapes reveals that an additional 7.7% of shortening was accumulated as ductile, micro-scale strain. This increases the total shortening in the entire cross-section of the Southern Altiplano at 21° S to 60km or 21%. In addition, I suggest that the contribution of outcrop-scale structures possibly accounts for another 20 km. 3D strain analysis further shows that the 7.7% of microscale strain were accompanied by 13% orogen-parallel extension. These shortening estimates more than double the published shortening values from the Altiplano. Crustal thickening and plateau uplift in the arc-backarc domain of the South American convergent margin took place during the Cenozoic. K-Ar and Ar-Ar age-dating on syn-tectonic sediments, together with seismic-sequence analysis, demonstrates that the Southern Altiplano structure formed during two independent compressional increments (Early Oligocene [〉27 Ma] and Middle/Late Miocene [17-8 Ma]), which were preceded by an Eocene/Oligocene extensional event that led to the formation of a half graben in the Central, and possibly a second in the Eastern Altiplano. Horizontal contraction of the Altiplano ended between 11-8 Ma, was indicated by the age of undeformed volcanic rocks. Detailed seismic analysis of single syn-tectonic basins combined with isotopic ages of syntectonic sediments, reveal a complex deformation history characterised by spatially and temporally irregular fault activation, which excludes the existence of large-scale eastward or westward propagating deformation during plateau formation. This diffuse pattern of deformation was characteristic for the entire plateau domain, i.e. from the western flank to the eastern edge of the Eastern Cordillera, during a first stage of plateau formation between 30 and 10 Ma. This possibly indicates that the plateau has remained flat since its formation and did not evolve from an initially doubly-vergent orogen. The syn-tectonic stratigraphic units of the Southern Altiplano domain overlie shallow marine, Late Cretaceous sediments that still form a sub-horizontal regional near sea level. This indicates that plateau surface-uplift in this part of the plateau was mainly achieved by sedimentary in fill of tectonically-controlled, internally-drained basins, and not by tectonic uplift. The tectonic evolution of the Southern Altiplano was largely accompanied by magmatic activity. An episode of strong volcanic activity affected the entire width of the Altiplano and adjacent parts of the Eastern Cordillera between 25-8 Ma. However, a causal relationship between magmatism and deformation could not be shown for the Southern Altiplano. Strong Oligocene/Miocene volcanic activity, together with the diffuse pattern of deformation, suggests that the formation of the Altiplano Plateau was initiated by magmatically-controlled thermal weakening of the crust, possibly as the result of the removal of the mantle lithosphere. At present, the Altiplano has a flat topography, high heat-flow, and is spatially related to a variety of geophysical anomalies that are interpreted as partial melting of the middle crust (20-40km depth). From this evidence, I propose that the process of plateau formation is still active.

Description: Abstract

Description: C/N mass ratios remain constant throughout MIS 3 and into MIS 2, with values between 6.3 and 8.9, indicating no significant terrestrial input of organic matter (Fig. 3). Low %TOC values during the interstadial increase from 0.4 to 0.7 between 57.8 and 43.7 kyr BP with a concurrent gradual increase in δ13C(organic) amid oscillations between −23.2‰ and −26.1‰ (Fig. 3). %TOC falls to 0.4 between 40.9 and 39.4 kyr BP whereas δ13C(organic) remains high at c. 24‰ with a peak value of −23.6‰ at 39.4 kyr BP. The subsequent two-stage increase in %TOC from 39 to 37.9 kyr BP and between 37.3 and 36.9 kyr BP is marked by a period of δ13C(organic) lowering to c. −26.6‰ before δ13C(organic) increases after 37.9 kyr BP to −24.8‰, values comparable to those prior to the %TOC decline at 40.9 kyr BP.

Description: Abstract

Description: Down-core variations of the high-resolution magnetic susceptibility (0.1 cm steps)have been obtained for kasten and pilot cores from sites CON01-603 and CON01-605. This allowed the transfer of AMS 14C dating performed on kasten cores to the performed on kasten cores to the pilot cores subjected to paleomagnetic investigations. Note the discrepancies in the magnetic susceptibility curves from the pilot core from site CON 01-605 (Vydrino Shoulder) measured in 2001 and 2003, respectively (right). Several large peaks visible in the first measurement from 2001 (dashed lines) disappeared after a 2-year-long storage. This is a first hint for the presence the ferromagnetic, chemically unstable greigite.