Am. Patwardhan et al., SEISMICITY IMPACT IN PATAN-TALUKA, DISTRICT SATARA, MAHARASHTRA, Journal of the Geological Society of India, 46(3), 1995, pp. 275-285
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.