Magnitude estimation of regional earthquakes in India and its adjoining region

To provide reliable and quick estimation of magnitude for moderate to large earthquakes at regional distances, two magnitude relations specific to the peninsular shield have been proposed based on long-period magnitude (MA) and energy magnitude (ME), using broadband velocity data of 23 regional events recorded at 18-station seismic network in the state of Telangana and Andhra Pradesh, India. MA is estimated using amplitude of filtered (0.03–0.08 Hz) broadband velocity seismograms, while ME is estimated based on radiated energy using broadband velocity spectra. It is observed that MA for larger events with Mw≥7.2 saturates, whilst ME does not suffer from saturation even for larger events. Thus, it is apparent that these two magnitude relations can provide magnitude estimates without saturation for all moderate to large regional earthquakes, which, in turn, can provide a homogeneous catalogue for mod- erate to large regional Indian earthquakes. The data transmission from remote stations to the central server at CSIR-National Geophysical Research Institute (NGRI) is quasi-real-time since it is connected by GPRS and VSAT. Using the proposed region specific magnitude relationships it becomes possible to estimate reliable magnitudes for moderate to large regional Indian earthquakes (Mw≤7.2) within 30 min of the occurrence of an event.



B Naresh, Prantik Mandal, Solomon Raju, R Vijaya Raghavan, G Suresh and D Srinagesh (2020) J. Earth Syst. Sci. 129:112