SEISMICITY IMPACT IN PATAN-TALUKA, DISTRICT SATARA, MAHARASHTRA

The continued sesmicity in the Koyna region has had the maximum impact in the Patan Taluka of the Satara District in Maharashtra within 30 k m radius from the epicentral region of earthquakes. The government of Maharashtra has undertaken rehabilitation of the villages which have s uffered the damage and are threatened also by the collapsing edges of the overhanging lateritic cliffs. On the M.M. intensity scale the dama ges suffered by the settlements and lateritic plateau would indicate a n intensity between VII and VIII. A high acceleration, maximum of 0.1g (100cm/sec(2)), is inferred for the soil profiles and alluvial tracts, loose gravel colluvium, river terraces material and weathered basalts on which the settlements are located. The continued seismicity around Koyna reservoir is often referred to as ''reservoir induced'', but su ch a mechanism is considered valid only for earthquakes whose hypocent ers lie far below in the basement rocks (depth > 3km), the magnitude f requency relationship (26 year period) is similar to that observed in any tectonically active regions. It seems that the seismicity is relat ed more to the reactivation of basement faults, reflected also in the overall geomorphological features of the region.