EGM 2010 International Workshop Adding new value to Electromagnetic, Gravity and Magnetic Methods for Exploration Capri, Italy, April 11-14, 2010 Heterogeneity in Kutch (India), an intraplate seismic region from gravity data A. R. Bansal, V. K. Rao, V. P. Dimri and K. K. Babu * National Geophysical Research Institute (NGRI, CSIR) Uppal Road, Hyderabad – 500 606 * Presenting Author Summary The gravity data of the tectonically complex region of Kutch (India) is analyzed using scaling spectral method in an attempt to understand intraplate seismicity in the region. The high-resolution multi-taper spectrum is used to calculate the depth values following scaling spectral method. Variation in depth values and scaling exponents are indication of crustal heterogeneities caused by far field tectonic stresses. Introduction The mechanism of intraplate earthquakes is poorly understood. In India, two confirmed cases of crustal intraplate earthquakes, namely the 1997 Jabalpur and 2001 Bhuj earthquakes (Kutch region) have been reported. The earthquake of Bhuj (26 January 2001, M w 7.6) was the largest earthquake since 1819 in the area. There is no surface rupture but a known tectonic feature was found responsible for the earthquake (Bodin and Horton, 2004), because this earthquake was located on a moderately dipping blind thrust fault. Seismicity in the Kutch region is a matter of debate and concern for earth scientists in order to understand the nature and properties of intraplate earthquakes in the Kutch region ( Gupta et al., 2001). The Bhuj earthquake occurred in the Kutch rift region, which has a long history of development from a Precambrian orogen - referred to as the Delhi trend (Biswas, 1987). The Kutch area has long history of development from the Precambrian and is overlain by number of faults like Kutch mainland fault, South Wagad fault and various lineaments. The scaling spectral method (Pilkington et al., 1994; Maus and Dimri, 1996; Fedi et al., 1997) is applied to found the depth values and scaling exponents from gravity data of the Kutch region. The gravity map (Mishra et al., 2005) and nine selected profiles (e.g. four East – West, five NE- SW) to calculate depth values and scaling exponents is presented in Figure 1.