BACKGROUND SEISMICITY AND STRENGTH OF COUPLING IN THE SUBDUCTION ZONES

The trend of background seismicity, N(n), in subduction zones is found to be related to the age of the plate at the trench, T, and the relative convergence speed, V, by N(n) = a T(b)V(c)(b, c > 0). The scatter in the data, however, suggests that parameters other than T and V also influence the background seismicity. The number of aftershocks is weakly correlated with N(n). Since the background seismicity increases with both T and V whereas the maximum magnitude, M(w), increases with V but decreases with T, no relationship exists between the strength of the coupling (as measured by M(w)) and the background seismicity.