Multi-Parametric Approach for Earthquake Precursor Detection in Assam Valley (Eastern Himalaya, India) using Satellite and Ground Observation Data

摘要

In present study soil radon (Rn-222) emanation, geomagnetic total field intensity (B-total), and total electron content (TEC) in ionosphere prior to M-w 5.5, Kokrajhar, Assam earthquake of September 12, 2018 were investigated using multiparametric geophysical observations at Ouguri Hills, Tezpur, Assam. Prominent anomalies were observed in the soil Rn-222 emanation, B-total and TEC time series prior to the event and are discussed. It was observed that soil Rn-222 persisted anomalies 50 days prior to the earthquake event. The correlation coefficient between soil Rn-222 with soil temperature and soil pressure was estimated to be feeble, 0.2 and -0.4 during the investigation period. Similar anomalies were observed 26 days prior to the earthquake event in B-total. The ionospheric TEC also persisted anomalies 17 days prior to the event. The amount of anomalous values observed for soil Rn-222, B-total, and ionospheric TEC ranged between -15.61 to 25.02 KBq/m(3), -83.33 to 10.50 nT and -13.06 to 7.09 TECU below LB and above UB respectively. An increase of 1.92 nT and a decrease of -36.77 nT of daily rate change was observed during the anomaly period compared to the normal days. The study revealed possibility of precursor detection through multi parametric approach from ground to ionosphere level.