Seismicity and the subduction process
Abstract
There is considerable variation between subduction zones in the largest characteristic earthquake within each zone. Assuming that coupling between downgoing and upper plates is directly related to characteristic earthquake size, we have tested for correlations between variation in coupling and other physical features of subduction zones: the lateral extent and penetration depth of Benioff zones, age of subducting lithosphere, convergence rate, and backarc spreading. Using linear multivariate regression, coupling is correlated with two variables: convergence rate and lithosphere age. Secondary correlations within the data set are penetration depth versus lithosphere age, and lateral extent versus convergence rate. An important additional correlation is that backarc spreading is found to be associated with subduction zones where coupling is low (those characterised by small earthquakes). Taken together, the observed correlations suggest a simple qualitative model where convergence rate and lithosphere age determine the horizontal and sinking rates, respectively, of slabs: these parameters influence the seismic coupling in the subduction zone. In the limit of a fast sinking rate and slow convergence rate, backarc spreading occurs and thereby appears to be a passive process.
 Publication:

Physics of the Earth and Planetary Interiors
 Pub Date:
 October 1980
 DOI:
 10.1016/00319201(80)90117X
 Bibcode:
 1980PEPI...23..240R
 Keywords:

 Earthquakes;
 Plates (Tectonics);
 Seismology;
 Subduction (Geology);
 Vertical Motion;
 Convergence;
 Lithosphere;
 Long Term Effects;
 Rates (Per Time);
 Vertical Distribution