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Full Seismic Waveform Modelling and Inversion
Springer Verlag, 2010
Wolfgang Sproessig and Andreas Fichtner
Eagle Publishing, 2005
I am Assistant Professor for Computational Seismology at the Swiss Federal Institute of Technology (ETH) in Zurich. In January 2010 I received my PhD from the University of Munich for my work on Full Seismic Waveform Inversion for Structural and Source Parameters. During my postdoc at Utrecht University , I worked on the development of resolution analysis and multi-scale methods for seismic waveform inversion.
My principal research interests include the development and application of methods for full seismic waveform inversion, resolution analysis in tomography, earthquake source inversion, as well as the study of novel seismic observables such as rotations and strain. For my work I received the Keiiti Aki Award 2011 .
Through the co-supervision of several students I am involved in the Sample Project of the German Research Foundation and in the European Initial Training Network QUEST.
Selection of recent work :
The Iceland-Jan Mayen plume system and its impact on mantle dynamics: We present a high-resolution shear wave velocity model of the North Atlantic region, revealing structural features in unprecedented detail down to a depth of 1300 km.Highlights of the model in the upper mantle include a well-resolved Mid-Atlantic Ridge and two distinguishable strong low-velocity regions beneath Iceland and beneath the Kolbeinsey Ridge west of Jan Mayen. A sublithospheric low-velocity layer is imaged beneath much of the oceanic lithosphere, consistent with the long-wavelength bathymetric high of the North Atlantic. The low-velocity layer extends locally beneath the continental lithosphere of the southern Scandinavian Mountains, the Danish Basin, part of the British Isles and eastern Greenland. All these regions experienced post-rift uplift in Neogene times, for which the underlying mechanism is not well understood. The spatial correlation between the low-velocity layer and uplifted regions suggests dynamic support by low-density astenosphere originating from the Iceland and Jan Mayen hotspots. Our model further suggests a lower-mantle source for the Iceland and Jan Mayen hotspots. Two distinguishable low-velocity conduits are imaged, connecting the upper-mantle anomalies beneath Iceland and Jan Mayen into the lower mantle. Both conduits are tilted to the South-East, reflecting the westward motion of the Mid-Atlantic Ridge. read more
Resolution analysis in full waveform inversion: We propose a new method for the quantitative resolution analysis in full seismic waveform inversion that overcomes the limitations of classical synthetic inversions while being computationally more efficient and applicable to any misfit measure.This allows us to infer 3-D distributions of direction-dependent resolution lengths and the image distortion introduced by the tomographic method. Our method allows for problem-dependent variations of the theme and for adaptations to exploration scenarios and other wave-equation-based tomography techniques that employ, for instance, georadar or microwave data. read more
Full waveform tomography for radially anisotropic structure: New insights into present and past states of the Australasian upper mantle : We combine spectral-element simulations and adjoint techniques in a non-linear full seismic waveform tomography for the radially anisotropic structure of the Australasian upper mantle. Our method allows us to explain 30 s waveforms in detail, and it yields tomographic images with locally 2 degree lateral resolution. Our model allows us to draw inferences concerning the past and present states of the Australian upper mantle and the formation of seismic anisotropy. read more