Seismicity in the Koyna-Warna Reservoir Site in Western India: Fractal and b-Value Mapping

Abstract

The Koyna–Warna region in western part of India is a unique site of reservoir-triggered seismicity where continuous seismic activity has been going on over the last 40 yr. We have analyzed the seismicity of this region in terms of the spatial variation of fractal dimension and have compared it with the frequency-magnitude relation b -value. About 1000 well-located events recorded during 1996–2005 in the Koyna–Warna region are selected for the analysis. The study region is divided into 18 grids, 0.05°×0.05°, with an overlapping window of 0.025°. Fractal dimension ( D ) and b -value of each grid are estimated and contour maps are prepared. The results show a moderately positive correlation between D and b -value that indicates a slowly loaded system with a steady state of stress distribution. The impact of reservoir loading on both the parameters (fractal dimension D and b -value) is a unique contribution for this area.