GEOLOGICAL CONTACTS, THERMAL SPRINGS AND EARTHQUAKES IN PENINSULAR INDIA

The occurrence of thermal springs in Peninsular India shows a distinct pattern that is related to geological contacts, tectonic units and earthquakes. It is observed that most of these thermal springs occur either near the contact of two geological units or along prominent tectonic units in the Peninsular Shield. The seismicity map of Peninsular India from historical times up to 1990 for earthquakes of magnitude > 3.5 indicates a striking correlation between seismicity and thermal springs. The b-values which characterize the thermal spring areas of the western coast are higher (0.8-1.1) than those obtained in similar areas in the rest of the Peninsular Shield (0.47-0.6). This indicates that the stresses are released by frequent micro- to moderate earthquakes in the thermal springs area along the west coast of India, whereas in Peninsular India the stress release is through infrequent moderate earthquakes.