ALBERT

Description: The 9th TRACE conference (Tree Rings in Archaeology, Climatology and Ecology) was organized by the Institute for Forest Growth, University of Freiburg, on April 22nd – 25th 2010 in Freiburg, Germany. [...] This volume of TRACE Proceedings contains 26 short papers and gives an overview of the wide spectrum of fields in tree-ring research.

Description: This thesis summarizes the results of the WSM project’s second phase (1996‐2008). In particular it presents the major achievements that have been accomplished with the WSM 2008 database release that has been compiled under the guidance of the author. Furthermore, the thesis briefly presents three of the author’s numerical models that aim at quantification the temporal changes of the crustal stress field.

Description: [...] In context of this work, a new damage mechanism is proposed: the mechanically induced fracture face skin. This new mechanism results from mechanical interactions between the proppants and the reservoir rock, due to the increasing stress on the rock-proppant system during production. Proppant embedment into the fracture face and proppant crushing leads to fines production and can impair the fracture performance. In order to achieve sustainable, longterm productivity from a reservoir, it is indispensable to understand the hydraulic and mechanical interactions in the rock-proppant system. In order to analyse the hydraulic and mechanical interactions, laboratory experiments using three different flow cells were conducted. These flow cells were used to localise and quantify the mechanical damage at the fracture face, as well as to investigate the long-term stability of a rock-proppant system under in-situ reservoir conditions. [...]

Description: This short report describes the first attempt at obtaining a preliminary cross-border risk model for Central Asia starting from datasets that were already available at the beginning of the EMCA Project.

Description: The magnetic field of the Earth varies in space and time. Geomagnetism as research area that aims to describe and understand the sources of these variations is supported by two pillars: first, regular high-precision measurements in the global network of magnetic observatories and repeat stations are necessary to register the field and its variations at all. Second, mathematical methods are required in order to extract magnetic field models from this large data set. Methods applied to data offer insights in the mechanisms generating the magnetic field. This thesis covers both subjects. In a first part, following the description of the state of the art in observatory instrumentation, I explain in detail two instruments that have the potential to streamline the classical procedures: The Geomagnetic AUtomated SyStem GAUSS paves the way to automated absolute measurements, up to now only possible manually. The newly developed DI3 technique improves and simplies the standard manual measurements signicantly and thus reduces the requirements placed on observers. The second part deals with the mathematical tools available for geomagnetic field modelling. I focus on harmonic splines that can be derived from the classical approach of spherical harmonics. These base functions are interpolatory and have a localised shape while satisfying Laplaces equation. Hence, they are applicable to fit data regionally or globally. The harmonic splines are used with a data set made of repeat station and observatory measurements from Southern Africa. This region is of special interest because the field intensity is very low and and both spatial and temporal field gradients exist. Subdivided into an analysis of ancient (years 1961-2001) and recent (2005-2009) data, two continuous regional field models SAMS and X-SAMS are derived. From the analysis of the field models, a better understanding of the field behaviour is gained. Finally, the harmonic splines are used in a case study on globally distributed secular variation data. Rotating the data set in a system of coordinates aligned with the dipole axis and modelling it with the harmonic splines reveals the external origin of observed fast variations.

Description: [...] In this thesis, data from seismic and infrasound stations were analyzed in order to see effects of tsunamis of the great Sumatra-Andaman 2004 and Tohuku-Oki 2011 earthquakes. Data used are from seismic stations of the Global Seismic Network (GSN) around the Indian and Pacific oceans and from infrasound stations of the International Monitoring System of the Comprehensive Test Ban Treaty Organization (IMS/CTBTO). In both data sets, seismic and infrasound, tsunami signals are observed in the period range of 500to2000s. These data may add to two new very useful observables for tsunami early warning systems. [...]

Description: The present work tries to condense the state‐of‐the‐art for the exploration and exploitation of geothermal energy. Although a lot of experiences from different sites worldwide are integrated in this study, some sections do reflect the German experience. For example, the German Renewable Energy Sources Act (EEG, see page 78) enables also a specific promotion and growth of the geothermal sector in Germany by guaranteeing special feed‐in tariffs for a 20‐years period. During the last years, several countries worldwide have introduced similar renewable energy promotion policies (some of them restricted to certain energy sources only or requiring a certain renewable energy quote), supporting investigations also in geothermal applications. Thus, the experiences in Germany may be of some value. Dependent on the political‐economical framework, the geothermal exploration and exploitation of deeper reservoirs represents an excellent option to extend geothermal applications also in areas where shallow geothermal reservoirs may not be able to match the local energy demand. Therefore, also challenges related to the exploration and exploitation of deep low‐permeability reservoirs are included in this study.

Description: [...] In order to construct the 3D structural model of the Norwegian continental margin, all mentioned datasets were compiled and gridded separately for each layer. The gridded data were merged into the 3D structural model and, therefore, all obtained thickness maps and structural depth maps are spatially consistent in 3D.

Description: Megacities as challenge for interdisciplinary research: the "Risk Habitat Megacity" research initiative / Dirk Heinrichs, Kerstin Krellenberg. - Mega-urban societies at risk / Frauke Kraas, Carsten Butsch. - Megacity Istanbul: earthquake risk and early warning in a megacity / Stefano Parolai, Jochen Zschau, Claus Milkereit, Matteo Picozzi, Angelo Strollo. - Neapel in der Zange / Thomas Walter

Description: The theme of this thesis is to investigate the sensitivity of several different formations of future satellite gravity missions. The work has three main aspects. The first, and the most important, is the development and testing of a global directional wavelet transformation as a mathematical tool to analyse sensitivity of satellite gravity mission. This is done by propagating full covariance matrices w.r.t. the spherical harmonics functions onto the directional wavelet transform. For the first time, we are able to accurately quantify the stripes that are typical for the error pattern of the GRACE gravity mission. The second aspect is the simulation of a satellite gravity formation, in order to achieve accuracy information in the form of a full covariance matrix. The third aspect involves analyzing results from the GRACE mission, which is already in orbit and has been delivering data since 2002. We compare the simulations of GRACE to the data delivered by the GRACE mission. This way, we are able to establish a relationship between the simulations and real-life data and evaluate the quality of the simulations.