Earthquake activity related to seismic cycles in a model for a heterogeneous strike-slip fault |
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| Authors: | Gert Zller Sebastian Hainzl Yehuda Ben-Zion Matthias Holschneider |
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| Institution: | aInstitute of Physics and Institute of Mathematics, University of Potsdam, Potsdam, Germany;bInstitute of Geosciences, University of Potsdam, Potsdam, Germany;cDepartment of Earth Sciences, University of Southern California, Los Angeles, USA;dInstitute of Mathematics, University of Potsdam, Potsdam, Germany |
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| Abstract: | We investigate the evolution of seismicity within large earthquake cycles in a model of a discrete strike-slip fault in elastic solid. The model dynamics is governed by realistic boundary conditions consisting of constant velocity motion of regions around the fault, static/kinetic friction and dislocation creep along the fault, and 3D elastic stress transfer. The fault consists of brittle parts which fail during earthquakes and undergo small creep deformation between events, and aseismic creep cells which are characterized by high ongoing creep motion. This mixture of brittle and creep cells is found to generate realistic aftershock sequences which follow the modified Omori law and scale with the mainshock size. Furthermore, we find that the distribution of interevent times of the simulated earthquakes is in good agreement with observations. The temporal occurrence, however, is magnitude-dependent; in particular, the small events are clustered in time, whereas the largest earthquakes occur quasiperiodically. Averaging the seismicity before several large earthquakes, we observe an increase of activity and a broadening scaling range of magnitudes when the time of the next mainshock is approached. These results are characteristics of a critical point behavior. The presence of critical point dynamics is further supported by the evolution of the stress field in the model, which is compatible with the observation of accelerating moment release in natural fault systems. |
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| Keywords: | Earthquake dynamics Fault models Seismicity Ruptures Heterogeneities Criticality |
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