Virtual California earthquake simulations: simple models and their application to an observed sequence of earthquakes

Numerical simulations are routinely used for weather forecasting. It is clearly desirable to develop simulation models for regional seismicity. One model that has been developed for the purpose is the Virtual California (VC) simulation. In order to better understand the behaviour of seismicity simulations, we apply VC to three relatively simple problems involving a straight strike-slip fault. In problem I, we divide the fault into two segments with different mean earthquake interval times. In problem II, we add a central strong (asperity) segment and in problem III we change this to a weak central segment. In all cases we observe limit cycle behaviour with a wide range of periods. We also show that the historical sequence of 13 great earthquakes along the Nankai Trough, Japan, exhibits a limit-cycle behaviour very similar to our asperity model.