Properties of Foreshocks and Aftershocks of the Non-Conservative SOC Olami-Feder-Christensen Model: Triggered or Critical Earthquakes?

TL;DR

This study compares the properties of earthquake sequences generated by the OFC model with real seismicity, finding qualitative similarities but notable quantitative differences, and discusses implications for triggered and critical earthquake models.

Contribution

It demonstrates that the OFC model can reproduce many features of real seismicity and explores its relation to triggered and critical earthquake theories.

Findings

OFC model shares qualitative properties with real seismicity.

Foreshock properties depend on mainshock magnitude.

OFC catalogs can be approximated by the ETAS model with weaker clustering.

Abstract

Following Hergarten and Neugebauer [2002] who discovered aftershock and foreshock sequences in the Olami-Feder-Christensen (OFC) discrete block-spring earthquake model, we investigate to what degree the simple toppling mechanism of this model is sufficient to account for the properties of earthquake clustering in time and space. Our main finding is that synthetic catalogs generated by the OFC model share practically all properties of real seismicity at a qualitative level, with however significant quantitative differences. We find that OFC catalogs can be in large part described by the concept of triggered seismicity but the properties of foreshocks depend on the mainshock magnitude, in qualitative agreement with the critical earthquake model and in disagreement with simple models of triggered seismicity such as the Epidemic Type Aftershock Sequence (ETAS) model [Ogata, 1988]. Many other features of OFC catalogs can be reproduced with the ETAS model with a weaker clustering than real seismicity, i.e. for a very small average number of triggered earthquakes of first generation per mother-earthquake.