Subsequent projects

Rotational motions: a new observable for seismology

This project focuses on developments in the emerging field of rotational seismology. We use collocated measurements of rotational motions and translations (standard seismometers) to perform tomographic imaging of the Earth’s interior. Using so-called array methods we can use the vast USArray data to estimate rotational motions and test the applicability of our methodology to map the Earth’s upper mantle structure. The project will  allow us to complement the LMU/TUM expertise in ring laser technology, theoretical wave propagation and inverse theory with the expertise in global seismology and array methods at our Californian partner institution. In addition, we would like to extend the resolution of the ring laser installed at the Californian site in order to extend the domains of applicability to free oscillations and noise studies. One of the most important goals of this collaboration is the attempt to seek further funding to establish a geophysical observatory that records all ground motion observables in the broadband frequency range of seismology (translations, strains, and rotations).

Primary project: Earthquake-Induced Rotational Motions

Final Report

The cooperation between LMU Geophysics and the Geophysical Institute at La Jolla, CA, aimed at 1) applying recently developed theoretical concepts to the data of the US seismic Array and 2) to further our efforts to generate funding for a multi-component ring laser system to be installed either at our Californian partner institution or in our Munich Department. In the course of the project data from the US Array were used for the first time to array-derive rotational motions and compare them with the translational motions to obtain subsurface velocity information (i.e., seismic tomography). In this context the sensitivity of seismic observations including rotations with respect to seismic sources was analysed with the clear observation that this additional motion component improves the resolution power. The most important output that resulted in part through the LMU-SCRIPPS cooperation was the successful application of the PI to an advanced grant of the European Research Council in 2012. This ERC Grant generates funding for a multi-component ring laser system that will be installed in the Geophysical Observatory in Fürstenfeldbruck, Germany (ROMY Project, BaCaTeC funding was also used to update and improve the performance of the ring laser system run by the Californian group.

Bernauer, M., A. Fichtner, and H. Igel (2014), Optimal observables for multi-parameter seismic tomography, Geophys. J. Int., 198(2), 1241-1254, doi:10.1093/gji/ggu204.


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