Seismology - Dynamic triggering of earthquakes

The Landers earthquake of 1992 triggered a series of earthquakes in other parts of California, focusing attention on the mechanism of remote triggering. Laboratory experiments on granular material under pressure suggest that triggering is a result of seismic waves impinging on a fault and inducing elastic nonlinear behaviour of the fault core, accompanied by instantaneous weakening and failure. The resulting ‘softening-to-weakening’ model fits in well with field observations of real earthquakes.