A Note on Probability of Occurrence of Largest Earthquake in Jharkhand State (India) and Nearby Region Based on Gumbel's Extreme Value Theory

Seismicity of Jharkhand state resembles to that of Stable Continental Region (SCR) and has experienced nearly 30 earthquakes of magnitudes ranging from 3 to 6 during the last 147 years. These earthquakes are shallow and crustal in nature which are scattered all over the region. However during the last 10 to 15 years there has been increase in the occurrence of seismic events. The study of plot of earthquake energy release versus time indicates that the earthquake of magnitude 6 may occur in and around the year 2060. The probabilistic analysis shows a high probability of occurrence of seismic events with M > 5 in 50 years of time interval and such interval increases with increase of earthquake magnitude. The return period for magnitudes 6 and above is quite high (80 to 100 years) where as for lower magnitudes the probability of occurrence ranges from 7 to 22 years. This periodicity of 100 years for magnitude 6 is approximately matching with the trend of magnitude energy release plot. However in view of the development and upcoming of high rise buildings in the region the smaller events and longer return period of damaging earthquake must not be ignored.