Statistical properties of the one-dimensional Burridge-Knopoff model of earthquakes obeying the rate and state dependent friction law

TL;DR

This study uses extensive simulations of a one-dimensional earthquake model obeying rate and state friction laws to analyze statistical properties, revealing characteristic rupture lengths and event classifications with implications for real seismicity.

Contribution

It provides a detailed statistical analysis of the Burridge-Knopoff model with rate and state friction, highlighting characteristic rupture lengths and event types, and explores the continuum limit.

Findings

Rupture length distribution follows an exponential decay at large sizes.

Two event types: unilateral and bilateral with asperity features.

Characteristic rupture length estimated at ~100 km, limiting maximum event size.

Abstract

Statistical properties of the one-dimensional spring-block (Burridge-Knopoff) model of earthquakes obeying the rate and state dependent friction law are studied by extensive computer simulations. The quantities computed include the magnitude distribution, the rupture-length distribution, the mainshock recurrence-time distribution, the seismic time correlations before and after the mainshock, the mean slip amount, and the mean stress drop at the mainshock, etc. Events of the model can be classified into two distinct categories. One tends to be unilateral with its epicenter located at the rim of the rupture zone of the preceding event, while the other tends to be bilateral with enhanced "characteristic" features resembling the so-called "asperity". For both types events, the distribution of the rupture length $L_r$ exhibits an exponential behavior at larger sizes, $\approx \exp[-L_r/L_0]$ with a characteristic "seismic correlation length" $L_0$. The mean slip as well as the mean stress drop tends to be rupture-length independent for larger events. The continuum limit of the model is examined, where the model is found to exhibit pronounced characteristic features. In the continuum limit, the characteristic rupture length $L_0$ is estimated to be $\sim $100 [km]. This means that, even in a hypothetical homogenous infinite fault, events cannot be indefinitely large in the exponential sense, the upper limit being of order $\sim 10^3$ kilometers. Implications to real seismicity are discussed.