Long-term earthquake prediction in Iran based on the time- and magnitude-predictable model

Abstract

The region of Iran has been divided into 21 seismogenic source areas on the basis of certain seismological and geomorphological criteria. In each of these source areas, the inter-event times between successive main shocks with magnitudes equal to or larger than certain cut-off magnitudes were considered. These inter-event times as well as the magnitudes of the main shocks have been used to determine the following relationships by a multilinear regression technique: log T t = 0.10M min + 0.36M p – 0.33 log M 0 + 6.97 M f = 0.66M min – 0.29M p + 0.61 log M 0 – 10.69 where T t is the calculated inter-event time measured in years, M min is the magnitude of the smallest main shock considered, M p and M f are the magnitudes of the preceding and following main shocks and M ̇ 0 is the annual seismic moment release in each source area. These relationships express the basic idea of the time- and magnitude-predictable model from which given the time of occurrence and the magnitude of the last main shock in a certain seismogenic source area, one can calculate the time of occurrence and the magnitude of the next main shock in that area by using the first and second of the equations respectively. However, as there is considerable scatter in the observations, conditional probabilities for the occurrence of a main shock during the next 10 years (1993–2002), as well as the magnitude of the expected main shock in each seismogenic source area were determined.