Complexity in hydroseismicity of the Koyna-Warna region, India

Koyna region in India is known to be the largest case of the Reservoir Triggered Seismicity (RTS) in the world with M6.3 earthquake in 1967. The region is seismically active even after forty five years with occurrences of earthquakes up to M5.0. The porous crustal rocks of Koyna - Warna region respond to changes in the prevailing stress / strain regime. These changes induce variations in the water level in bore wells before, during and after an earthquake and their study can help in understanding the earthquake genesis in the region. The fractal dimension of water levels in the bore wells of the region can be used as measure of the nonlinear characteristics of porous rock, revealing the underlying complexity. In this paper we present values of fractal dimensions of the water level data in the bore wells using the non-linear time series methodology. The spatio - temporal changes in the fractal dimensions have also been studied. The results show that hydro-seismically the region behaves as a low -dimensional non-linear dynamical system.