Authors(s): A. Vasanthi
Date of Publication: March, 2025
Publication reference: J. Ind. Geophys. Union, 29(2) (2025), 124-131
Abstract:
Indian subcontinent has been experiencing intraplate seismicity since historical times having witnessed a number of damaging earthquakes. Recently, on December 4, 2024, Godavari graben was rocked by a moderate earthquake (M=5.0) close to Mulugu town in Telangana state of India. It has a focal depth of around 10 km. Earlier too, this graben has experienced a number of moderate magnitude destructive earthquakes. We have analyzed high-resolution satellite gravity data over this region in order to identify the active faults and genesis of this intraplate earthquake. The residual gravity anomaly, deduced using Finite Element Method, brought out a clear expression over different geologic and tectonic features. Eastern flank of Godavari graben is seen to be characterized by extremely high-gradient gravity anomalies corresponding to a deep-seated crustal-level fault, over which the hypocenter of the Mulugu earthquake lies. Similarly, western flank is also associated with high gravity gradients, corresponding to a fault structure which also reaches to mid-crustal depth. These seismogenic faults are getting reactivated due to neo-tectonic activities caused possibly by underlying thermal anomaly. It appears that all the major intra-plate earthquakes of Indian shield have occurred along the prominent rift structures, which are associated with high heat flow and thin lithosphere, and have undergone quaternary uplifting and crust-mantle thermal interaction.
Keywords: Intraplate seismicity, Deep-seated crustal fault, Godavari graben, Mulugu earthquake; Gravity field; FEM (Finite Element Method); Heat flow..