Asperity characteristics of the Olami-Feder-Christensen model of earthquakes

TL;DR

This study uses numerical simulations to analyze the Olami-Feder-Christensen earthquake model, revealing that asperity-like phenomena result from self-organized stress concentration, which explains repeated seismic events at specific sites.

Contribution

It demonstrates that asperity formation in the OFC model is due to self-organized stress concentration, linking periodic asperity events to the model's transmission parameter.

Findings

Asperity formation is linked to stress self-organization.

Repeated asperity events occur at the same epicenter with a period set by the transmission parameter.

Asperity events tend to cluster in time and space.

Abstract

Properties of the Olami-Feder-Christensen (OFC) model of earthquakes are studied by numerical simulations. The previous study indicated that the model exhibits ``asperity''-like phenomena, {\it i.e.}, the same region ruptures many times near periodically [T.Kotani {\it et al}, Phys. Rev. E {\bf 77}, 010102 (2008)]. Such periodic or characteristic features apparently coexist with power-law-like critical features, {\it e.g.}, the Gutenberg-Richter law observed in the size distribution. In order to clarify the origin and the nature of the asperity-like phenomena, we investigate here the properties of the OFC model with emphasis on its stress distribution. It is found that the asperity formation is accompanied by self-organization of the highly concentrated stress state. Such stress organization naturally provides the mechanism underlying our observation that a series of asperity events repeat with a common epicenter site and with a common period solely determined by the transmission parameter of the model. Asperity events tend to cluster both in time and in space.