A linked stress release model for historical Japanese earthquakes: coupling among major seismic regions

A linked stress release model is proposed for the analysis of spatial interaction of earthquake occurrences through stress transfer within a large area of the Earth’s crust. As an example, the model is used for statistical analysis for the Japanese historical earthquakes in central Japan and offshore in the Nankai and Sagami troughs with magnitude M ≥ 6.5 during the period from 1400 to 1997. This area is divided into four smaller regions of roughly comparable size and activity. Based on the Akaike information criterion (AIC), the results demonstrate the existence of coupling between certain of the regions. With the evidence that the crust may lie in a near-critical state, this has implications for the possible triggering of earthquakes at long distances from the origin event. In particular, we find evidence for the dependence of Nankai trough events on the Chubu/Kinki triangle region, whose events are themselves dependent on the the Fossa Magna/Sagami trough. Evidence for the validity of the model includes simulation results indicating that the model had a higher forecast hazard post-1991 for an event in the Chubu/Kinki triangle region than did models not incorporating regional coupling.