Translation, Strain and Rotation: New Approaches to SeismicProcessing and Inversion
Final Report Abstract
This project was motivated by recent advances in measuring strain and rotational ground motions. Several studies, enabled by the project, show that strain and rotations can significantly contribute to better constrained models of Earth’s structure and seismic sources. 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, was developed. A series of examples , including rotational ground motions and strain, 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. Moreover, we analyzed for the first time if rotational ground motion measurements are useful for a more detailed description of earthquake source processes. 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. The results of this project could potentially be tested in the field in the very near future as adequate rotation sensors will become available in the next 1-2 years.
Publications
- (2014), Optimal observables for multiparameter seismic tomography, Geophysical Journal International, 198(2), 1241-1254
Bernauer, M., Fichtner, A. & Igel, H.
(See online at https://doi.org/10.1093/gji/ggu204) - (2014), Reducing non-uniqueness in finite source inversion using rotational ground motions, Journal of Geophysical Research: Solid Earth, 119(6), 4860-4875
Bernauer, M., Fichtner, A. & Igel, H.
(See online at https://doi.org/10.1002/2014JB011042) - (2015), Rotational Seismology: Theory, Instrumentation, Observations, Applications, in Encyclopedia of Complexity and System Science, edited by WHK Lee, Springer-Verlag New York
Igel, H., M. Bernauer, J. Wassermann, and K. U. Schreiber
- Inversion for seismic moment tensors combining translational and rotational ground motions. Geophysical Journal International, Volume 207, Issue 1, 1 October 2016, Pages 562–570
Donner, S., Bernauer, M., Igel, H.
(See online at https://doi.org/10.1093/gji/ggw298)
