The most important tool are computer simulations of seismic wave propagation and of earthquake processes in geologically active regions of the world. Since the number of parameters can easily be on the order of many millions, a finite difference approximation to obtain derivatives of a numerical mode is completely out of question.
These waves pass through the Earth at speeds of more than 10 km per second at times, collecting data about its inner structure — just as an x-ray passes through the human body, gathering information.
Subduction of continental lithosphere in the Banda Sea region: Complete seismic waveforms have rarely been used even though they promise images at much higher resolution. This work is intended to contribute to the development of joint source-structure inversions of ambient noise correlations, and in particular to an understanding of the extent to which source-structure trade-offs may be reduced.
It may be interpreted as the slab that caused the opening of the Liguro-Provencal basin through successive roll-back between Ma.
It images diffractors with dimensions of roughly a quarter of a wavelength and potentially allows to discriminate density from elastic structure.
We demonstrate that processing transforms the actual wavefield sources and Andreas fichtner thesis wave propagation physics into effective sources and effective wave propagation. During my postdoc at Utrecht UniversityI worked on the development of resolution analysis and multiscale methods for seismic waveform inversion.
Despite the fact that all ambient noise inverse problems are special in terms of their receiver configuration and data, some general statements concerning source-structure trade-offs can be made: Geophysical Journal International, Using synthetic full-waveform inversions as benchmarks, we demonstrate that auto-correlations of random-model applications to the Hessian yield various resolution measures, including direction- and position-dependent resolution lengths, and the strength of inter-parameter mappings.
Model of the Earth made up of millions of small tetrahedra, with topography raised and shear-wave velocity at km depth. Our central theme is not to equate interferometry with Green function retrieval, and to extract information directly from processed interstation correlations, regardless of their relation to the Green function.
Waveform inversion can be interpreted as a diffraction tomography. We observe that the required number of random test models is around 5 in one, two and three dimensions.
This work is intended to provide a comprehensive theoretical foundation of full-waveform interferometry by correlation, and to suggest improvements to current passive monitoring methods.
Moreover, he has found expressions for waveform sensitivity kernels which are necessary for a detailed sensitivity and resolution analysis. Measurements of translation, rotation and strain: This combination of modern mathematical methods of computer simulation, along with the availability of high-performance computers at the CSCS, make it Andreas fichtner thesis to study the structure and dynamics of the Earth with unprecedented accuracy.
Full waveform tomography for upper-mantle structure in the Australasian region using adjoint methods Geophysical Journal International, A unified concept for comparison of seismograms using transfer functions Geophysical Journal International, Increasingly complex models of density and elastic structure of the crust and mantle are now in use to explain a wide range of processes in mantle convection and its surface expression plate tectonics.
In addition to the well-studied Alboran slab, a strong E-W trending high-velocity anomaly is present around km depth beneath the Algerian coast.
Seismic waveform inversion on continental scales Advisors: Full waveform tomography for radially anisotropic structure: No mantle plumes can be detected beneath the European Cenozoic rift system, including the Massif Central.
Kennett, Andreas Fichtner, In addition to tomographic problems, resolution analysis by random probing may be used in other inverse methods that constrain continuously distributed properties, including electromagnetic and potential-field inversions, as well as recently emerging geodynamic data assimilation.
Optimal spherical spline filters for the analysis and comparison of regional-scale tomographic models Physics of the Earth and Planetary Interiors,September Andreas Fichtner Department of Earth Sciences Swiss Federal Institute of Technology (ETH) Sonneggstrasse 5 Zurich, Switzerland CURRICULUM VITAE PERSONAL DATA Name: Andreas Fichtner Date of birth: June 7, PhD thesis (completed) on rotational seismology, Ludwig Maximilian University.
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Christian Boehm, Mauricio Hanzich, Josep de la Puente, and Andreas Fichtner 78 th EAGE Conference and ExhibitionExpanded Abstracts, Vienna, Thesis Andreas Fichtner, Full Seismic Waveform Modelling and Inversion, Springer Verlag, Heidelberg. Table of Contents (pdf) (PDF, 93 KB) Foreword by .Download