A Study of Deep Geoelectric Structure and Its Relation to Seismotectonics and Economic Development of Saurashtra Region, Western India

The Saurashtra Peninsula and its adjoining regions covered by Deccan Traps (DT) are one of the
important parts of the Indian continental lithosphere with interesting geophysical anomalies, tectonothermal
evolution since the Mesozoic times. Knowledge on the deep structure beneath these
formations is important for understanding the seismo-tectonics and economic development of the
region. This region has gained importance after the occurrence of a major earthquake (7.9 Mw) north
of Saurashtra, namely Bhuj earthquake during 2001. It is also observed that Saurashtra region has
also experienced several earthquake swarms limited to small regions.. In our study, magnetotelluric
results of the deep crustal structure along five NS oriented traverses are presented. The five traverses
are—Halvad-Rohisa (HR), Sapar-Iswaria (SI), Mota Dahinsara-Bamagadh (MB), Jodiya-
Jamkhandorna (JJ) and Vav Beraja-Devda (VD). The total length of these 5 traverses is about 670
km. The derived deep geoelectric structure is also compared and correlated with gravity data to get
more confidence on the derived results. The 2-D geoelectric section has delineated buried sediments
below the Basalt and also anomalous high conductivity structure at places extending from 20 km to
about 40 km. From the spatial correlation, anomalous high conductive structure derived from MT data
with intense localized seismic activity is an interesting observation. In the present study, the results of
magnetotelluric studies along with other geophysical results are presented. Additionally, the outcome
of the present study has implications in economic development of the region in a big way. It is
suggested to initiate large infrastructure near Chotila region of Gujarat and one can plan to store large
amount of crude hydrocarbons in deep buried sediments through drilling of 1-1.5 km and can be
recovered back when needed.