Christian Pelties
Ludwig-Maximilians-University of Munich
Fakultät für Geophysik - Department Geo- und Umweltwissenschaften

Prof. Jean-Paul Ampuero
California Institute of Technology, Pasadena (CALTECH)
Seismological Laboratory

Understanding the physics of earthquakes is one of the current grand challenges of Earth science. Earthquake rupture is a complex process that involves multiple coupled phenomena and occurs at depths that cannot be probed directly. Computer simulations of dynamic rupture are an essential tool for basic research in earthquake science and applied research in earthquake hazard. Computational earthquake dynamics involves physics-based modeling of fault slip, seismic wave propagation and the resulting ground motions, and is enabled by advanced numerical algorithms and high-performance computing.br>
The aim of this LMU-Caltech collaborative research project is to apply the software SeisSol, recently developed at LMU, to address open questions in earthquake dynamics. In particular, we will study the influence of low-velocity fault zone structures on dynamic rupture and highfrequency ground motion generation. Better insights in these fields have the potential to improve seismic hazard assessment.

Final report:

During this BaCaTeC research project, we have studied the effects of 3D fault zones on dynamic earthquake ruptures and high-frequency ground motion by using the software SeisSol. Our successful collaboration included two research visits and a short course on recent developments in the field of earthquake dynamics. Furthermore, it led to a publication entitled “Pulse-like rupture induced by three-dimensional fault zone flower structures” in the Journal of Pure and Applied Geophysics and a presentation at the EGU 2013 General Assembly in Vienna, Austria [1,2].

Thanks to the high resolution and flexible mesh generation of SeisSol, we extended previous 2D dynamic rupture simulations to 3D and studied the effect of generic fault zone flower structures. We found that the mechanism of generation of slip pulses identified in 2D simulations also operates in 3D. In addition, we discovered a new mechanism of generation of slip pulses induced by unloading waves radiated when the rupture reaches the surface. Our results suggest that the generation of slip pulses in fault zones is robust to the complexity of 3D fault zone structures and provides a new insight into the observed near-fault high-frequency ground motions. Future research is warranted incorporating complex fault geometries and fault zone structures and studying their effects on dynamic rupture propagation in realistic earthquake scenarios.

[1] Pelties, C., Y. Huang, and J.-P. Ampuero (2014), Pulse-like rupture induced by three-dimensional fault zone flower structures, Pure Appl. Geophys., doi: 10.1007/s00024-014-0881-0.

[2] Pelties, C., Y. Huang, and J.-P. Ampuero (2013), Pulse-like rupture induced by three-dimensional fault zone flower structures, EGU General Assembly Conference Abstracts, 15, 269