科研之友
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摘要
P>A model is presented that treats an earthquake as the failure of asperities in a manner consistent with modern concepts of sliding friction. The mathematical description of the model includes results for elliptical and circular asperities, oblique tectonic slip, static and dynamic solutions for slip on the fault, stress intensity factors, strain energy and second-order moment tensor. The equations that control interaction of asperities are derived and solved both in a quasi-static tectonic mode when none of the asperities are in the process of failing and a dynamic failure mode when asperities are failing and sending out slip pulses that can trigger failure of additional asperities. The model produces moment rate functions for each asperity failure so that, given an appropriate Green function, the radiation of elastic waves is a straightforward calculation. The model explains an observed scaling relationship between repeat time and seismic moment for repeating seismic events and is consistent with the properties of pseudo-tachylites treated as fossil asperities. Properties of the model are explored with simulations of seismic activity that results when a section of the fault containing a spatial distribution of asperities is subjected to tectonic slip. The simulations show that the failure of a group of strongly interacting asperities satisfies the same scaling relationship as the failure of individual asperities, and that realistic distributions of asperities on a fault plane lead to seismic activity consistent with probability estimates for the interaction of asperities and predicted values of the Gutenberg-Richter a and b values. General features of the model are the exterior crack solution as a theoretical foundation, a heterogeneous state of stress and strength on the fault, dynamic effects controlled by propagating slip pulses and radiated elastic waves with a broad frequency band.
- 出版日期2010-9
