Relation of Mean Time Interval with Magnitude for Earthquakes in Northeast India and Its Surrounding Region

Abstract

Based on active tectonics, structural orientation, focal mechanism of earthquakes and seismicity level, Northeast India and its surrounding region has been divided into five seismogenic zones namely, the Eastern Himalaya as Zone 1, the Eastern Himalaya Syntaxis as Zone 2, the Shillong plateau and Mikir hill as Zone 3, the Naga-Disang as Zone 4 and the Eastern Boundary as Zone 5. In the present study we proposed relation between earthquake mean time interval and the magnitude for earthquakes in these five seismogenic zones. We model the variation of the mean time interval with four different distribution models viz. the Poisson's, the Weibull's, the log-Weibull and the lognormal distributions. The mean time interval is found to be following the log-normal model the most amongst the four models tested in this study. The coefficients of the relation between logarithm of mean time interval and the magnitude as estimated from the complete catalog selected by two time windows exhibit mild differences limited to ± one standard deviation uncertainty in the coefficient and decreasing with an increase in the catalog time window length.