Fakultät für Geowissenschaften - Digitale Hochschulschriften der LMU Archiv

The scientific investigation of the solid Earth's complex processes, including their interactions with the oceans and the atmosphere, is an interdisciplinary field in which seismology has one key role. Major contributions of modern seismology are (1) the development of high-resolution tomographic images of the Earth's structure and (2) the investigation of earthquake source processes. In both disciplines the challenge lies in solving a seismic inverse problem, i.e. in obtaining information about physical parameters that are not directly observable. Seismic inverse studies usually aim to find realistic models through the minimization of the misfit between observed and theoretically computed (synthetic) ground motions. In general, this approach depends on the numerical simulation of seismic waves propagating in a specified Earth model (forward problem) and the acquisition of illuminating data. While the former is routinely solved using spectral-element methods, many seismic inverse problems still suffer from the lack of information typically leading to ill-posed inverse problems with multiple solutions and trade-offs between the model parameters. Non-linearity in forward modeling and the non-convexity of misfit functions aggravate the inversion for structure and source. This situation requires an efficient exploitation of the available data. However, a careful analysis of whether individual models can be considered a reasonable approximation of the true solution (deterministic approach) or if single models should be replaced with statistical distributions of model parameters (probabilistic or Bayesian approach) is inevitable. Deterministic inversion attempts to find the model that provides the best explanation of the data, typically using iterative optimization techniques. To prevent the inversion process from being trapped in a meaningless local minimum an accurate initial low frequency model is indispensable. Regularization, e.g. in terms of smoothing or damping, is necessary to avoid artifacts from the mapping of high frequency information. However, regularization increases parameter trade-offs and is subjective to some degree, which means that resolution estimates tend to be biased. Probabilistic (or Bayesian) inversions overcome the drawbacks of the deterministic approach by using a global model search that provides unbiased measures of resolution and trade-offs. Critical aspects are computational costs, the appropriate incorporation of prior knowledge and the difficulties in interpreting and processing the results. This work studies both the deterministic and the probabilistic approach. Recent observations of rotational ground motions, that complement translational ground motion measurements from conventional seismometers, motivated the research. It is investigated if alternative seismic observables, including rotations and dynamic strain, have the potential to reduce non-uniqueness and parameter trade-offs in seismic inverse problems. In the framework of deterministic full waveform inversion a novel approach to seismic tomography is applied for the first time to (synthetic) collocated measurements of translations, rotations and strain. The concept is based on the definition of new observables combining translation and rotation, and translation and strain measurements, respectively. Studying the corresponding sensitivity kernels assesses the capability of the new observables to constrain various aspects of a three-dimensional Earth structure. These observables are generally sensitive only to small-scale near-receiver structures. It follows, for example, that knowledge of deeper Earth structure are not required in tomographic inversions for local structure based on the new observables. Also in the context of deterministic full waveform inversion a new method for the design of seismic observables with focused sensitivity to a target model parameter class, e.g. density structure, is developed. This is achieved through the optimal linear combination of fundamental observables that can be any scalar measurement extracted from seismic recordings. A series of examples illustrate that the resulting optimal observables are able to minimize inter-parameter trade-offs that result from regularization in ill-posed multi-parameter inverse problems. The inclusion of alternative and the design of optimal observables in seismic tomography also affect more general objectives in geoscience. The investigation of the history and the dynamics of tectonic plate motion benefits, for example, from the detailed knowledge of small-scale heterogeneities in the crust and the upper mantle. Optimal observables focusing on density help to independently constrain the Earth's temperature and composition and provide information on convective flow. Moreover, the presented work analyzes for the first time if the inclusion of rotational ground motion measurements enables a more detailed description of earthquake source processes. The complexities of earthquake rupture suggest a probabilistic (or Bayesian) inversion approach. The results of the synthetic study indicate that the incorporation of rotational ground motion recordings can significantly reduce the non-uniqueness in finite source inversions, provided that measurement uncertainties are similar to or below the uncertainties of translational velocity recordings. If this condition is met, the joint processing of rotational and translational ground motion provides more detailed information about earthquake dynamics, including rheological fault properties and friction law parameters. Both are critical e.g. for the reliable assessment of seismic hazards.

Remote sensing has become an essential tool to improve data collection and spatial analysis in the geosciences. Identification of passive margin structures that are exposed along the Egyptian coast of the Red Sea, and their control on landforms has been hampered by limited data resolution and restricted access to this arid and inaccessible region. A major challenge lies in distinguishing features in the landscape that formed due to long-term tectonic activity and erosion from those features that modified the landscape recently. The goals of this thesis were to determine to what degree the study area is currently tectonically active, and what major hazards might affect the touristically developing coastal region. This study deals with the structural and geomorphological evolution of the rift-related structures and their impact on the sediment distribution and landforms variation in the northern Quseir area. In such a remote desert area, field and remote morphostructural analysis are needed to understand the structural and geomorphological evolution. The current study is mainly based on high-resolution QuickBird image analysis and field investigation. Field mapping was limited to one season, owing to acute safety concerns in the Eastern Desert. In the study area, the pre-rift stratigraphy includes Pan-African basement rocks overlain by pre-rift clastic and carbonate successions that range in age from Cambrian to Eocene. Syn-rift clastic and carbonate rocks range in age from Late Oligocene to recent and show depositional patterns controlled by fault systems. The field area exposes a section of a tectonically uplifted, amagmatic sedimentary sequence, which formed due to passive-margin-related rifting of the Red Sea: the Mesozoic and Tertiary sedimentary units that fill the 7-km wide coastal strip are perfectly exposed as tilted fault blocks. The results of my field mapping and structural analysis show that the fault architecture of the area is dominated by a large NW-SE-striking fault system. A series of SE-dipping normal faults are consistent in cross-section with listric fault geometry, rooting into an E-dipping detachment at depth. Our mapping also revealed that left-steps in at least one of the major NS- striking faults are accommodated by a flower structure, but not by SW-NE-oriented cross faults as previously proposed in a neighboring area. Thus seismic activity is more likely to occur on the large NW-striking normal faults, leading to potentially larger Magnitude earthquakes than previously recognized in the area. The left-step may act as a barrier to rupture propagation and should be examined in more detail. The northwestern Red Sea coast is part of the straight coastal segment that is generally characterized as seismically inactive. However, during the geological field mapping, I found evidence for Plio-/Pleistocene vertical coastal uplift, likely due to earthquake-related coastal and offshore faulting. Pliocene marine deposits emerged recently due to sea level-drop and earthquake-related uplift. Even the presence of up to five distinct Pleistocene coral terraces implies that at least some of the coastal uplift was seismogenic, because terraces of the same age can be found at different elevations along strike. Presumably, some of the seawarddipping, N-S-striking normal faults are active today, despite the lack of recent instrumental seismicity. These findings imply long recurrence intervals for active faults in the northern Quseir area. These results differ from previously published results for the adjacent Quseir-Um Gheig sub-basin area, were E-W-striking strike-slip faults were mapped to offset the N-Sstriking faults, and had been inferred as earthquake-generating faults by Abd El-Wahed et al. (2010). Based on our mapping, we postulate that the large rift-parallel normal faults are seismogenic. Drainage network evolution within the study area is often structurally controlled and the nature of these controls was examined in this study. The Wadi Siatin stream channel network is classified in a relatively simple way, based on the high-resolution satellite data, with dendritic, and rectangular considered the most fundamental channel geometries. It was possible to distinguish the different morphological elements of the network, as well as the anomalies that affect the patterns. This analysis revealed, in the northern Red Sea area basins, the existence of old structures whose successive reactivations have left their mark on the drainage network. Comparison of joint systems direction with the directions of the main trunk stream channel of Wadi Siatin shows that the channel is highly affected by tectonic jointing. First-order channels follow easily erodable faults. Investigations concerning the relationship of stream-flow orientation with geological structure in the Wadi Siatin Basin shows that, generally, the least influenced flows are those of first-order which are governed simply by the valley side slopes on which they developed. However, in certain geological and geomorphological situations, there are clear exceptions to this generalization. Certainly, locally, geological control of these small streams may be even higher than in many streams of higher order. In the peripheral parts of the Basin, expansion of drainage into the available space has obviously been easiest along lines of weakness and, as a consequence of this, streams of the first order come to exhibit a high degree of adjustment to the underlying structure. The maximum structural control is reached by the streams of the third order. Towards the higher orders, the influence of local structure becomes weaker.

The study deals with the two main problems in geographical education: How to inform students about a spatial practicing learning and teaching and how to evaluate this form of learning in comparison to theoretical non spatial forms of learning. The classic form of spatial learning is the outdoor excursion. But there are some new and actual alternatives when realizing the former intended aims of a spatial learning, so for instance didactical pathways, field trips or field works, but also the new way of geocaching and learning by GPS when dealing with the themes of orientation or finding out points of geographic importance for explaining the genetic processes. The necessary skills can be combined to improve the success of learning and to maximize the motivation. The base of this motivation behavior is the existence of a hide and seek-game as a modern version of a scavenger hunt. This motivates the students and is furthermore the attraction of Geocaching. Methodical skills can also be trained very automatically during this search. The GPS devices are of common use in the daily life and its use may increase much more in the fu-ture and in geographical use, too. Nowadays the literature about this theme is merely descriptive and thematically reduced to the function of orientation. The first study describing the learning suc-cess of using GPS devices and Geocaches in geography class had been made by NEEB. She tested the variation of the competence of orientation in different old classes when examining the use of GPS devices and Geocaches. Even though GPS devices and Geocaches are very efficient for instructing the students’ competence of orientation there may be the question, in what forms and circumstances the learning can be done. The time and effort necessary to generate a didactical and educational trail has to be justified against the background of the achieved learning effect. Educational trails need students, walking outside of the schools, looking for information along teaching paths and learning by the results. This active experienced learning leads to a better understanding of the environment, the outdoor circumstances and the people living in this area. You can structure such educational trails by Geopoints, this means points of a special geographic interest. Geocaches can structure such paths didactically. These structuring points are GEOpoints. The tasks at such Geopoints are structured didactical as well. GPS devices and Geocaches are complementing one another. They fulfill an important function in geographic orientation and the respective local information. Two important ministries in Germany (Bavaria, Baden-Württemberg) demand the use of extra¬curri-cu¬lar educational objectives in geography education. This means: visiting locations outside of the school and using the advantages of a fully learning by excursions. Neurobiology supports the idea that pupils completing the educational trail will learn much more and efficiently than students in “normal” classes: Indeed: A successful contextualization of modern geomedia stimulates the motivation. Geocaches are suitable for didactical structuration and motivation. A better and more comprehensive addressing to all senses will lead to a better sustainability. When testing the advantage of excursional learning comparing the same themes with a classical learning at school you have to differ within the students capacity of learning and the cognitive and methodical competence. For 17years aged students the theme of “Umgestaltung von Flusslandschaften“ (rearrangements of fluvial topography) was chosen because using this example of anthropogenic rearrangements of the Rheinaue wetlands near Karlsruhe shows the interdependency between human and environment was in the direct neighborhood of the students. Therefore the excursion could be realized very good without long transports. The “Nördlinger Ries” between the Swabian and the Franconian Jura is an impact-crater of world-wide importance. This location had been chosen for Students of grade 5 (10 years old students). The themes to work out were: The typical elements of the Swabian Jura (karst formation, hydrogeology, typical vegetation) and the special forms of the impact tectonics. The sustainability of educational trails using GPS had been evaluated by the answers of 441 ques-tionnaires. In grade 5 a multiple-choice-test had to be answered while grade 11 had to answer open questions in complete sentences. The influence of the teachers on the overall result is being kept low through the random selection, the number of the comparison groups and the teaching manuals. The overall results of these questionnaires show that the students of grade 5 which completed the educations trail achieved 11% higher scores in areas of the cognitive performance compared to the students who experienced classical learning at school. In grade 11 the students who completed the educational trail received 5% higher scores. Both differences in the results are significant and show a magnitude of effect, which is high in certain items. Consequently, the study has proven that educational trails evocate better cognitive performances than classical learning at school. The current state of research suggests that the development of environmental trails from teachers for teachers is not sustainable because the teachers don’t have the time to refine environmental trails didactically. The experience while creating the educational trails and the feedback of the participant teachers showed that teachers should cooperate for creating educational trails. The strain for each single person is reduced and the regularly use of the educational trails can be assured.

Seismische Tomographie ist die eindrücklichste und intuitivste Methode, Informationen über das tiefe Erdinnere, von der Kruste bis an die Kern-Mantel-Grenze zu erlangen. Die von entfernten Erdbeben aufgezeichneten Bodenbewegungen werden mit den für ein einfaches Erdmodell vorhergesagten verglichen, um ein verbessertes Modell zu erhalten. Dieses dreidimensionale Modell kann dann geodynamisch oder tektonisch interpretiert werden. Durch die Entwicklung leistungsfähiger Computersysteme kann die Ausbreitung seismischer Wellen mittlerweile im gesamten messbaren Frequenzbereich simuliert werden, sodass dieses gesamte Spektrum der Tomographie zur Verfügung steht. Die vorliegende Arbeit beschäftigt sich mit der Verbesserung der Wellenformtomographie. Zum einen wird die Nutzbarkeit eines komplexen Typs seismischer Wellen, der in der Mantelübergangszone zwischen 410 und 660 km Tiefe gestreuten triplizierten Wellen ge-zeigt. Diese Wellen versprechen eine erheblich bessere Auflösung der geodynamisch wichtigen Diskontinuitäten zwischen oberem und unterem Mantel als bisher verwendete teleseismische Wellen. Zum anderen wird der nichtlineare Einfluss des Erdbebenmodells auf die Wellenformtomographie untersucht. Mittels Bayesianischer Inferenz werden Wahrscheinlichkeitsdichten für die Herdparameter des Erdbebens, wie Tiefe, Momententensor und Quellfunktion bestimmt. Dazu wird zuvor ein Modell der Messunsicherheit und des Modellierungsfehlers in der Herdinversion bestimmt, das bis dato nicht vorlag. Dabei zeigt sich im Weiteren, dass der Effekt der Unsicherheit im Herdmodell eine nichtlineare und bisher weitgehend ignorierte Feh-lerquelle in der seismischen Tomographie ist. Dieses Ergebnis ermöglicht es, die Varianz seismischer Laufzeit- und Wellenformmessungen sowie die Kovarianz zwischen einzelnen Messstationen zu bestimmen. Die Ergebnisse dieser Arbeit können in Zukunft erheblich dazu beitragen, die Unsicherheiten der seismischen Tomographie quantitativ zu bestimmen, um eventuell vorhandene Artefakte zu zeigen und damit geologischen Fehlinterpretationen tomographischer Ergebnisse vorzubeugen.

Summary Problem. Pesticides play an important role in the agricultural production but their misuse affect the health of farmers and workers who manipulate such toxic substances. In the field of occupational hygiene, researches have been working in finding out the most appropriate method to estimate the human exposure in order to assess the risk and therefore to take the due decisions to improve the processes in the pesticide management and to reduce the health risk. Goals. The goal of this research was focused in creating a model for human exposure assessment specially for farming systems in developing countries by (i) evaluating the available models for human exposure assessment developed in industrialized countries, (ii) measuring the exposure in the study areas of potato and flower farming systems in Colombia, and (iii) proposing a pesticide flow model to estimate quantitatively the human exposure. Methods. The research was organized in three phases by using different methods, namely (i) evaluation of previous models of human exposure assessment (by means of a Multi-Criteria and Sensitivity Analysis); (ii) quantification of dermal exposures in Vereda La Hoya (by applying the Whole Body Dosimetry, Luminiscence Spectrometry and Tracer Method); and (iii) the development of a pesticide flow model for the human exposure assessment (by applying the Material Flow Analysis method). This model was built with dermal exposure measurements obtained in the study area of greenhouse flower crops in Sabana de Bogotá, Colombia. Results. DERM, DREAM, PHED and RISKOFDERM were selected as the most appropriate models to be applied in farming systems in developing countries as their determinants are relevant for the assessment of pesticide use and all the processes involved during the pesticide management. Afterwards these four models were applied to assess the dermal exposure in the case study of Vereda La Hoya and their determinants were compared with the characteristics of the study area, DREAM and DERM were found as the most appropriate models to assess the dermal exposure in these study areas. However, because some relevant determinants are still absent, the accuracy of these models could be improved if these are included. When comparing the final model assessment of dermal exposure in the study area, DREAM was found as the model that assesses more accurately the dermal exposure in this study area. In the study area of Vereda La Hoya, Colombia was found that the application was the activity with the highest PDE. Even though lower body parts (thighs and legs) were the most exposed, these body parts also showed the highest level of protection because of the work clothing. The ADE was high for arms and upper back due to the lack of adequate work clothing covering the complete arm and the direct contact of the upper back with the spills on the sprayer tank. Furthermore, it was found that Metamidophos is the most toxic pesticide used in Vereda La Hoya. Farmers may reduce significantly the health risk by using adequate work clothing made of appropriate fabrics that covers the whole body including the arms, cleaning properly all the pesticide residues left on the sprayer before each application, and avoiding the modification of nozzles using only nozzles with the standard discharge. The proposed pesticide flow model helps to identify the patterns of pesticide distribution on the body, the level of protection given by personal protective equipment and the estimates of potential and actual dermal and inhalation exposure. This information can be used to determine the health risk level by comparing the model estimates with the AEOL reference values for each pesticide. In addition, the model makes it possible to easily identify the activities or body parts that have high levels of exposure. This is useful in identifying improvements that will decrease the exposure during pesticide management. Because it is not feasible to measure directly the dermal exposure in all study areas, this model might help to obtain a quick estimation which could help stakeholders and authorities to make further decisions. Conclusions. This research evaluated in depth the available models for human exposure assessment, so assessors can decide which model is the most appropriate according to the characteristics of the study area in which the model is going to be applied and furthermore this research suggested improvements in the models in order to increase the estimation accuracy. This research also contributes in the proposal of a new model for human exposure based on the material flow analysis methodology studying the pesticide fractioning during the pesticide management in a certain interval of time. With this model quantitative estimations of human exposure are obtained which facilitate the risk assessment and the implementation of measures to improve the safety during the pesticide management and to decrease the risk. The proposed model also demonstrates the feasibility of applying the material flow analysis methodology in the field of human exposure, obtaining a tool that helps to understand the mechanisms of distribution of the pesticide in the farming system based on the processes involved and the flows between these processes.

In order to increase our understanding of magma mixing processes and their impact on the geochemical evolution of silicate melt we present in the following works, the first set of experiments performed using natural basaltic and rhyolitic melts. In particular, we investigate the interplay of physical dynamics and chemical exchanges between these two melts using time-series mixing experiments performed under controlled, chaotic, dynamical conditions. The variation of major and trace elements is studied in detail by electron microprobe (EMPA) and Laser Ablation ICP-MS (LA-ICP-MS) and the time-evolution of chemical exchanges during mixing is investigated. Using the concentration variance as a proxy to measure the rate of chemical element homogenization in time, a model to quantify chemical element mobility during chaotic mixing of natural silicate melts is proposed. The morphology of mixing patterns at different times is quantified by measuring their fractal dimension and an empirical relationship between mixing time and morphological complexity is derived. The complexity of mixing patterns is also compared to the degree of homogenization of chemical elements during mixing and empirical relationships are established between the fractal dimension and the variation of concentration variance of chemical elements in time. Finally we discuss the petrological and volcanological implications of this work.

The evolution of the vertebral column is marked by profound morphological changes that have a strong impact on organismal biology. The vital functions of the axial skeleton range from protecting the neural structures through sustaining the body posture to physiological aspects such as breathing. Archosaurs (crocodiles, birds and dinosaurs), as a group, display a striking variety of body plans and vertebral morphologies. This dissertation aims to contribute to the understanding of the pattern and the genetic basis for the evolution of the vertebral column in archosaurs. The transdisciplinary project comprises five chapters. Framed by a general introduction (chapter 1) and the conclusion (chapter 5), the second chapter considers, from a morphofunctional point of view, the question of (1) why differences in the vertebral column evolved. The present thesis revealed a strong link between the digitally simulated flexion pattern of the presacral vertebral column and the axial movements of modern archosaurs during related activities such as feeding and locomotion: this correlation allowed the inference of the feeding range and locomotor options in the extinct archosaur Plateosaurus. This long-necked dinosaur was primarily adapted as mid-level browser, obtaining food that was at or above the horizontal level of its head. There is currently no evidence to unambiguously interpret the locomotion style of Plateosaurus. The morphofunctional analysis supported both a quadrupedal and a bipedal posture. The third chapter addresses, from a molecular biology point of view, the question (2) of how modern taxa develop their vertebral columns. It provides insights into the genetic basis for the embryonic development of the vertebral column in modern archosaurs, which includes the highly conserved Hox genes. The Hox gene expression pattern was detected in the Nile crocodile (Crocodylus niloticus) via whole-mount in situ hybridisation experiments. Hox paralog genes 4 and 5 are expressed in the cervical region of the crocodile. The anterior expression limit of HoxC-6 marks the cervicothoracic transition. The expression of Hox paralog genes 7 and 8 is restricted to the dorsal series. The same Hox genes are expressed along the anteroposterior body axis of crocodiles, chickens and mice, but the pattern of expression is different. The comparative analysis revealed two general processes that are accompanied by evolutionary differences in the axial skeleton: 1) expansion and condensation as well as 2) a shift of genetic activity corresponding to different vertebral counts. The strong association between the anterior limits of the expression of specific Hox genes and the borders between morphological regions of the vertebral axis in a variety of vertebrate species stimulated the work presented in the fourth chapter. It considers the question (3) of whether we can infer that the development of the vertebral column took place in extinct animals. The direct correlation between vertebral Hox code and quantifiable vertebral morphology shows that the genetic code is deducible from vertebral morphology in modern crocodiles, chickens and mice. Applying these findings to the fossil relative Plateosaurus revealed that the hypothetical Hox code for the dinosaur would be generally similar to the crocodilian Hox gene expression pattern, but with the variation that the anterior region is expanded, as in birds. The integrative analysis (morphology, genes and fossils) of the vertebrae greatly enhanced our knowledge of evolutionary processes and provided valuable information about the possible reasons, genetic basis and pattern for evolutionary changes of the vertebral column in extant and extinct archosaurs.