STATISTICAL ANALYSIS OF EARTHQUAKE OCCURRENCES FOR SEISMIC RISK EVALUATION IN NORTHEAST INDIA

Validity of the assumption of Poisson distribution and the use of various magnitude-frequency relationships in seismic risk assessment studies have been analysed for the earthquake occurrences in northeast Indian region. It is found that the earthquakes of magnitude ۴.۵ or above are described well by the Poisson distribution. However, instead of the commonly used Gutenberg-Richter's relationship, large magnitude earthquakes should be described by a faster than linear decay of log N. These observations are further supported by studying the extreme-value distributions of the earthquake magnitude