Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

P. K. Agrawal , J. G. Negi

Abstract

An aeromagnetic map of the area west of Koyna (lr23' N, 73°45' E), bounded between latitude 17°5' Nand 17°35' N and longitude 73°15' E and 73°40' E, is spectrally analysed to derive a basement relief model. The model reflects structural heterogeneity conforming well with the existing estimates of trap thickness from other geophysical methods. Two prominent structural features-one near Chatnali and the other to the west of Durga Dongar-are observed which indicate fault-like structures. Between south of Alore and northeast of Mutagaon, a body with high reverse magnetization with its top lying at a depth of about 1200 m is also indicated. These results seem to indicate a limited triggering role of reservoir-induced seismicity in the region and point to the existence of pre-reservoir instability of the Koyna zone.

Keywords

Geophysics, Aeromagnetic Data, Deccan Traps, Koyna, Maharashtra, Spectral Analysis.

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J. G. Negi ¹, P. K. Agarwal ¹, O. P. Pandey ¹

Affiliations
1 National Geophysical Research Institute Hyderabad - 500 007, IN

Abstract

The multi-level aeromagnetic survey conducted over the Deccan traps in 1974 reflects a tectonic fault and thrust faulting environment near the Latur earthquake zone. The matching aeromagnetic thickness estimate with the drilling results calibrates thickness estimates at other places of aeromagnetic profiles and surveys and calls for a detailed future coverage of randomly magnetized Deccan traps by aeromagnetic surveys.

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