Geological heterogeneity and hydrological dynamics impact on triggered earthquake genesis in Deccan basaltic terrain of western India

Abstract

Reservoir triggered seismicity (RTS) have been documented at about 700 locations worldwide, with the Koyna-Warna region in Western India hosted the largest triggered earthquake of magnitude 6.3. Despite substantial work has been done to understand the genesis of triggered earthquakes around Koyna-Warna reservoirs, most of the research has been limited to the immediate areas of the reservoirs. In this study, we expand the investigation to encompass a broader area, aiming to explore the impact of geological heterogeneity and groundwater storage anomalies derived from GRACE satellite data on earthquake occurrence in the region. Utilising 30-m resolution digital elevation model, we extracted lineaments and generated lineament density and trend maps. Analysis reveals a total of 927 lineaments spanning 33.73 km, with shorter lineaments comprising 70% of the total count. Lineament density ranges from 0 to 1.8 km/km², indicating varying degrees of rock fracturing, with densities of 0.6–1.20 km/km² and 0.4–0.6 km/km² indicate high and moderate levels. Dominant lineament trends are observed in the N-S, NNW-SSE and WNW-ESE directions. Good correlation between lineament density, and earthquake occurrence is observed which is further validated from groundwater anomaly.