[S13-3] Earthquake source mechanics III

[S13-3-06] Seismic source spectra and the relation between corner frequency and source properties derived from spontaneous rupture of a circular fault

^○Jian Wen¹, Xiaofei Chen², Jianxuan Xu² (1.University of Science and Technology of China, Hefei, China, 2.Southern University of Science and Technology, Shenzhen, China)

Stress drop is an important dynamic source parameter for understanding the physics of source processes. The estimation of stress drops for moderate and small earthquakes bases on the measurements of corner frequency, seismic moment and a specific theoretical model of rupture behavior. As so far, there are several theoretical rupture models. However, different models will cause big difference for the estimation of stress drop, even in an idealized scenario of circular earthquake rupture. Moreover, those models are just kinematic models or quasi-dynamic models. Compared to previous models, we use the BIEM to simulate spontaneous dynamic rupture in homogeneous elastic full space and then to investigate the relation of corner frequency, seismic moment and source dynamic parameters. For unstable rupture, the relation between corner frequency and dynamic parameters coincides with that in previous models. One asymptote of the relation between the stress drop and the ratio of seismic moment and rupture radius is close to Eshelby's analytical solution for uniform stress drop. For self-arresting rupture, the scaling laws of corner frequency, seismic moment and stress drop are contrary to those for unstable rupture. Meanwhile, because corner frequency and seismic moment are two independent parameters obtained directly from observation, we check the relation between corner frequency and seismic moment. No matter whether rupture front for self-arresting rupture arrives at the barrier boundary or not, the relation between corner frequency and seismic moment coincides with the relation obtained from observation in which the corner frequency is inversely proportional to seismic moment. However, for unstable rupture, the relation between corner frequency and seismic moment cannot fit the observation.