A unified model for dynamic and static stress triggering of aftershocks, antishocks, remote seismicity, creep events, and multisegmented rupture

Abstract

Aftershocks have been thought to be triggered by static stress transfer. The 1992 Landers and 1999 Hector Mine, California, earthquakes have demonstrated the possibility of remote triggering of seismicity, highlighting the role of dynamic seismic waves. Static stress changes and transient deformations have different timescales. The mechanisms by which they trigger earthquakes are thought to be different, leading to an unwieldy vision of aftershock triggering. We propose a model that encompasses both static and dynamic triggering of aftershocks and antishocks as well as the occurrence of stable slip (creep events) or multisegmented rupture. The framework of this model is based on the stability/instability transition of faults. We propose that dynamic and static stress triggering pertain to the same physical process. We study the effect of the complete Coulomb failure function. We demonstrate the possibility of the triggering of seismicity by a dynamic stress pulse in a stress shadow zone characterized by a negative static stress field. The limited time efficiency of dynamic triggering shown by the data is explained by the model. We suggest that dynamic waves trigger only the most unstable faults associated with a relatively short characteristic time, while the static stress field triggers also faults that are stable, associated with a larger characteristic time.