Stress triggering of large earthquakes complicated by transient aseismic slip episodes

Abstract

[1] We investigate how a static stress change, caused by a nearby earthquake, perturbs sliding processes on a fault and the time to the next earthquake. For this purpose, we model numerically a reverse fault in a two-dimensional, semi-infinite and elastic medium, partly stable and partly unstable under a rate-and state-dependent friction law. When no stress change intervenes, steady sliding spreads out of the deep zone of frictional stability and keeps expanding updip during the interseismic period. Aseismic slip episodes (ASEs) develop spontaneously within the region of steady sliding and repeat quasi-periodically. When steady sliding has spread beyond a certain critical length (the nucleation length) above the zone of frictional stability, one of the ASEs undergoes rapid buildup and avalanches into high-speed seismic sliding. When a step-like stress change intervenes, ASEs of larger amplitudes arise and evolve similarly to their spontaneous counterparts until one of them avalanches into an earthquake. If the stress change arrives not too early nor too late in the seismic cycle, the basic picture is as follows: delaying the stress step, be it positive or negative, delays the timing of the ASE sequence and thereby postpones the next earthquake. When the stress step is delayed to more than a certain extent, however, an earlier ASE gets to evolve into an earthquake, advancing its time discontinuously. Only in the final stage of a seismic cycle does a positive stress step systematically advance the next earthquake and a negative stress step systematically delay it.

Regional seismicity of the Mid-Atlantic Ridge: observations from autonomous hydrophone arrays

“…The departures from the Modified Omori Law could also be due to the connection between the detachment faults with the hydrothermal circulation and that weak and very altered rocks can promote the existence of aseismic transient slip, diminishing the rate of earthquakes expected by the Modified Omori Law (Figs 8c, 9c and 10c), thereby adding more complexity to the normal process of tectonic rupture. This was widely observed on the oceanic seafloor near coastal regions using GPS stations situated nearby thrust faults on subduction areas (Cho et al 2009; Liu et al 2007; McGuire & Segall 2003). Also following on from the work of McGuire et al (2005), Figs 8(c) and 9(c) show that those sequences present foreshocks before the mainshock, with some of them even observed teleseismically and through no coincidence the p ‐value obtained for these sequences are the greatest.…”

Static Coulomb stress load on a three‐dimensional rate‐and‐state fault: Possible explanation of the anomalous delay of the 2004 Parkfield earthquake

“…Liu and Rice [] simulated aseismic transients on a plate boundary caused by static stress changes. Cho et al [] extensively investigated the effect of static stress changes on the occurrence of the next earthquake for various times and amplitudes of the static stress load, reporting discontinuities in the dependence of CA on the loading time.…”

Interval modulation of recurrent slow slip events by two types of earthquake loading

“…To investigate the external stress perturbation effect, we test a step-like (static) shear stress change during the interseismic period (e.g., Perfettini et al 2003;Cho et al 2009) in additional experiments. The details are described in a later discussion section.…”