Estimation of effective elastic thickness from gravity and topography data under the Deccan Volcanic Province, India

Effective elastic thickness (EET) under the Deccan Volcanic Province is estimated based on admittance and coherence between the gravity field and the topography. The observed admittance function shows a good fit for the regional compensation model with an EET of 10±2 km. The effect of a long-wavelength (geoidal) gravity anomaly on the computation of EET has been investigated and found not to significantly influence the value of EET although a considerable change in compensation depth was noticed. The estimated EET is less than the thickness of the seismically active layer in this region. These results are consistent with observations in other parts of the world that EET should be smaller than the depth of the 350±100°C isotherm.