ON THE VALIDITY OF TIME-PREDICTABLE MODEL FOR EARTHQUAKE GENERATION IN NORTH-EAST INDIA

North-east India is seismically very active and has experienced many widely-distributed shallow, large earthquakes. Earthquake generation model for the region was studied using seismicity data [(1906-1984) prepared by National Geophysical Data Centre (NGDC), Boulder Colorado, USA]. For establishing statistical relations surface wave magnitudes (M(s) greater-than-or-equal-to 5.5) have been considered. In the region four seismogenic sources have been identified which show the occurrences of at least three earthquakes of magnitude 5.5 less-than-or-equal-to M(s) less-than-or-equal-to 7.5 giving two repeat times. It is observed that the time interval between the two consecutive main shock depends on the preceding main shock magnitude (M(p)) and not on the following main shock magnitude (M(f)) revealing the validity of time predictable model for the region. Linear relation between logarithm of repeat time (T) and preceding main shock magnitude (M(p)) is established in the form of log T = cM(p) + a. The values of c and a are estimated to be 0.36 and 1.23, respectively. The relation may be used for seismic hazard evaluation in the region.