The b-value and fractal dimension of local seismicity around Koyna Dam(India)

Earthquakes began to occur in Koyna region(India) soon after the filling of Koyna Dam in 1962. In the present study, three datasets 1964–1993, 1993–1995, and1996–1997 are analyzed to study the b-value and fractal dimension. The b-value is calculated using the Gutenberg–Richter relationship and fractal dimension Dcorr.using correlation integral method. The estimated b-value and Dcorr.of this region before 1993 are found to be in good agreement with previously reported studies. In the subsequent years after 1995, the b-value shows an increase. The estimated b-values of this region are found within the limits of global average. Also, the pattern of spatial clustering of earthquakes show increase in clustering and migration along the three zones called North-East Zone, South-East Zone(SEZ), and Warna Seismic Zone. The earthquake events having depth B5 km are largely confined to SEZ.After 1993, the Dcorr.shows decrease, implying that earthquake activity gets clustered. This seismic clustering could be helpful for earthquake forecasting.