Analysis of fluid-induced seismicity patterns around four water reservoirs

Seismicity patterns around four water reservoir lakes namely, Koyna (Maharashtra), Idukki (Kerala), Bhatsa (Maharashtra) and Kadana (Gujarat) of the Peninsular shield were analysed using time series techniques for identifying the stochastic model of natural background seismicity and transfer function model of fluid-induced seismicity. A predominant 12 months periodicities were observed in cross correlation functions between pore pressure variations and fluid-induced seismicity patterns. Drained seismicity response was predominant in the frequency response function at Koyna and Bhatsa reservoirs which are possibly due to pore pressure diffusion in the fractured shallow earth's crust.