Refine
Year of publication
- 2014 (17) (remove)
Document Type
- Doctoral Thesis (17) (remove)
Is part of the Bibliography
- yes (17) (remove)
Keywords
- induced seismicity (2)
- 3D geomechanical numerical model (1)
- 3D geomechanisch-nummerische Modellierung (1)
- Attribut-Analysen (1)
- Aufenthaltsdauer (1)
- Bergsturz (1)
- Bodenwassergehalt (1)
- Common-Reflection-Surface (1)
- Cyprus arc (1)
- Deformationsquellenmodellierung (1)
- Dendroklimatologie (1)
- Denudation (1)
- Finnmark Platform (1)
- Geomorphologie (1)
- Geophysik (1)
- Georadar (1)
- Himalaya-Tibet Orogen (1)
- Himalaya-Tibet orogen (1)
- Holozän (1)
- InSAR (1)
- Indian Monsoon (1)
- Krustenstruktur der Süd-Türkei (1)
- Krustenstruktur des Eratosthenes Seeberges (1)
- Llaima Vulkan (1)
- Llaima volcano (1)
- Loppa High (1)
- Momententensor (1)
- Paläogeographie (1)
- Partikel Swarm Optimierung (1)
- Quartär (1)
- Quellenumkehr (1)
- Ringstörungen (1)
- Seismologie (1)
- Spannungsmuster (1)
- Stabile Sauerstoff- und Kohlenstoffisotope (1)
- Tectona grandis (1)
- Tendürek Vulkan (1)
- Tendürek volcano (1)
- Tropen (1)
- UV-Lasermikrodissektion (1)
- UV-laser microdissection (1)
- Untergrund (1)
- Verarbeitung seismischer Daten (1)
- Wellengeschwindigkeit (1)
- Zypernbogen (1)
- aktive Weitewinkel-Seismik (1)
- beginnende Kontinent-Kontinent Kollision (1)
- circular statistics (1)
- controlled source wide angle seismic (1)
- cosmogenic nuclides (1)
- crustal stress (1)
- crustal structure of south central Turkey (1)
- crustal structure of the Eratosthenes Seamount (1)
- deformation source modeling (1)
- dendroclimatology (1)
- denudation (1)
- earthquake location (1)
- geomorphology (1)
- geophyics (1)
- geothermischer Reservoire (1)
- global inversion (1)
- globale Inversion (1)
- ground-penetration radar (1)
- holocene (1)
- incipient continent-continent collision (1)
- indischer Monsun (1)
- induzierten Seismizität (1)
- kosmogene Nuklide (1)
- krustale Spannungen (1)
- microseismicity (1)
- moment tensor (1)
- oxygen and carbon stable isotopes (1)
- paleogeography (1)
- particle swarm optimisation (1)
- quaternary (1)
- ring-fault (1)
- rockslide (1)
- seismic (1)
- seismic attributes (1)
- seismic sequence stratigraphy (1)
- seismische Attribute (1)
- seismische Sequenzstratigraphie (1)
- seismische Stapelungs-Methode (1)
- seismology (1)
- soil water content (1)
- source duration (1)
- source inversion (1)
- stress pattern (1)
- subsurface (1)
- tectonic stress (1)
- tektonische Spannungen (1)
- tropics (1)
- wave velocities (1)
- zirkulare Statistik (1)
Institute
- Institut für Geowissenschaften (17) (remove)
In March 2010, the project CoCoCo (incipient COntinent-COntinent COllision) recorded a 650 km long amphibian N-S wide-angle seismic profile, extending from the Eratosthenes Seamount (ESM) across Cyprus and southern Turkey to the Anatolian plateau. The aim of the project is to reveal the impact of the transition from subduction to continent-continent collision of the African plate with the Cyprus-Anatolian plate. A visual quality check, frequency analysis and filtering were applied to the seismic data and reveal a good data quality. Subsequent first break picking, finite-differences ray tracing and inversion of the offshore wide-angle data leads to a first-arrival tomographic model. This model reveals (1) P-wave velocities lower than 6.5 km/s in the crust, (2) a variable crustal thickness of about 28 - 37 km and (3) an upper crustal reflection at 5 km depth beneath the ESM. Two land shots on Turkey, also recorded on Cyprus, airgun shots south of Cyprus and geological and previous seismic investigations provide the information to derive a layered velocity model beneath the Anatolian plateau and for the ophiolite complex on Cyprus. The analysis of the reflections provides evidence for a north-dipping plate subducting beneath Cyprus. The main features of this layered velocity model are (1) an upper and lower crust with large lateral changes of the velocity structure and thickness, (2) a Moho depth of about 38 - 45 km beneath the Anatolian plateau, (3) a shallow north-dipping subducting plate below Cyprus with an increasing dip and (4) a typical ophiolite sequence on Cyprus with a total thickness of about 12 km. The offshore-onshore seismic data complete and improve the information about the velocity structure beneath Cyprus and the deeper part of the offshore tomographic model. Thus, the wide-angle seismic data provide detailed insights into the 2-D geometry and velocity structures of the uplifted and overriding Cyprus-Anatolian plate. Subsequent gravity modelling confirms and extends the crustal P-wave velocity model. The deeper part of the subducting plate is constrained by the gravity data and has a dip angle of ~ 28°. Finally, an integrated analysis of the geophysical and geological information allows a comprehensive interpretation of the crustal structure related to the collision process.
An important contribution of geosciences to the renewable energy production portfolio is the exploration and utilization of geothermal resources. For the development of a geothermal project at great depths a detailed geological and geophysical exploration program is required in the first phase. With the help of active seismic methods high-resolution images of the geothermal reservoir can be delivered. This allows potential transport routes for fluids to be identified as well as regions with high potential of heat extraction to be mapped, which indicates favorable conditions for geothermal exploitation. The presented work investigates the extent to which an improved characterization of geothermal reservoirs can be achieved with the new methods of seismic data processing. The summations of traces (stacking) is a crucial step in the processing of seismic reflection data. The common-reflection-surface (CRS) stacking method can be applied as an alternative for the conventional normal moveout (NMO) or the dip moveout (DMO) stack. The advantages of the CRS stack beside an automatic determination of stacking operator parameters include an adequate imaging of arbitrarily curved geological boundaries, and a significant increase in signal-to-noise (S/N) ratio by stacking far more traces than used in a conventional stack. A major innovation I have shown in this work is that the quality of signal attributes that characterize the seismic images can be significantly improved by this modified type of stacking in particular. Imporoved attribute analysis facilitates the interpretation of seismic images and plays a significant role in the characterization of reservoirs. Variations of lithological and petro-physical properties are reflected by fluctuations of specific signal attributes (eg. frequency or amplitude characteristics). Its further interpretation can provide quality assessment of the geothermal reservoir with respect to the capacity of fluids within a hydrological system that can be extracted and utilized. The proposed methodological approach is demonstrated on the basis on two case studies. In the first example, I analyzed a series of 2D seismic profile sections through the Alberta sedimentary basin on the eastern edge of the Canadian Rocky Mountains. In the second application, a 3D seismic volume is characterized in the surroundings of a geothermal borehole, located in the central part of the Polish basin. Both sites were investigated with the modified and improved stacking attribute analyses. The results provide recommendations for the planning of future geothermal plants in both study areas.
The tropical warm pool waters surrounding Indonesia are one of the equatorial heat and moisture sources that are considered as a driving force of the global climate system. The climate in Indonesia is dominated by the equatorial monsoon system, and has been linked to El Niño-Southern Oscillation (ENSO) events, which often result in severe droughts or floods over Indonesia with profound societal and economic impacts on the populations living in the world's fourth most populated country. The latest IPCC report states that ENSO will remain the dominant mode in the tropical Pacific with global effects in the 21st century and ENSO-related precipitation extremes will intensify. However, no common agreement exists among climate simulation models for projected change in ENSO and the Australian-Indonesian Monsoon. Exploring high-resolution palaeoclimate archives, like tree rings or varved lake sediments, provide insights into the natural climate variability of the past, and thus helps improving and validating simulations of future climate changes. Centennial tree-ring stable isotope records | Within this doctoral thesis the main goal was to explore the potential of tropical tree rings to record climate signals and to use them as palaeoclimate proxies. In detail, stable carbon (δ13C) and oxygen (δ18O) isotopes were extracted from teak trees in order to establish the first well-replicated centennial (AD 1900-2007) stable isotope records for Java, Indonesia. Furthermore, different climatic variables were tested whether they show significant correlation with tree-ring proxies (ring-width, δ13C, δ18O). Moreover, highly resolved intra-annual oxygen isotope data were established to assess the transfer of the seasonal precipitation signal into the tree rings. Finally, the established oxygen isotope record was used to reveal possible correlations with ENSO events. Methodological achievements | A second goal of this thesis was to assess the applicability of novel techniques which facilitate and optimize high-resolution and high-throughput stable isotope analysis of tree rings. Two different UV-laser-based microscopic dissection systems were evaluated as a novel sampling tool for high-resolution stable isotope analysis. Furthermore, an improved procedure of tree-ring dissection from thin cellulose laths for stable isotope analysis was designed. The most important findings of this thesis are: I) The herein presented novel sampling techniques improve stable isotope analyses for tree-ring studies in terms of precision, efficiency and quality. The UV-laser-based microdissection serve as a valuable tool for sampling plant tissue at ultrahigh-resolution and for unprecedented precision. II) A guideline for a modified method of cellulose extraction from wholewood cross-sections and subsequent tree-ring dissection was established. The novel technique optimizes the stable isotope analysis process in two ways: faster and high-throughput cellulose extraction and precise tree-ring separation at annual to high-resolution scale. III) The centennial tree-ring stable isotope records reveal significant correlation with regional precipitation. High-resolution stable oxygen values, furthermore, allow distinguishing between dry and rainy season rainfall. IV) The δ18O record reveals significant correlation with different ENSO flavors and demonstrates the importance of considering ENSO flavors when interpreting palaeoclimatic data in the tropics. The findings of my dissertation show that seasonally resolved δ18O records from Indonesian teak trees are a valuable proxy for multi-centennial reconstructions of regional precipitation variability (monsoon signals) and large-scale ocean-atmosphere phenomena (ENSO) for the Indo-Pacific region. Furthermore, the novel methodological achievements offer many unexplored avenues for multidisciplinary research in high-resolution palaeoclimatology.
Unterschiedliche Verfahren zur Ermittlung von Georadar-Wellengeschwindigkeiten wurden entwickelt und erfolgreich angewendet. Für die Verfahren wurden statistische Methoden und Schwarmintelligenz-Algorithmen benutzt. Es wurde gezeigt, dass die neuen Verfahren schneller, präziser und besser reproduzierbare Ergebnisse für Georadar-Wellengeschwindigkeit erzielen als herkömmliche Verfahren.
Mit verbesserten Werten der Georadar-Wellengeschwindigkeit lassen sich die verzerrten dreidimensionalen Abbilder der obersten zehn Meter des Untergrundes, welche sich mit Georadar-Daten erzeugen lassen, korrigieren. In diesen korrigierten Abbildern sind dann realistische Tiefen von Schichten oder Objekten im Untergrund besser messbar. Außerdem verbessern präzisere Wellengeschwindigkeiten die Bestimmung von Bodenparametern, wie Wassergehalt oder Tonanteil. Die präsentierten Verfahren erlauben eine quantitative Angabe von Fehlern der bestimmten Wellengeschwindigkeit und der daraus folgenden Tiefen und Bodenparametern im Untergrund. Die Vorteile dieser neu entwickelten Verfahren zur Charakterisierung des Untergrundes der oberen Meter wurde an Feldbeispielen demonstriert.