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Scientists find reason behind low magnitude earthquakes in western coast

New Delhi, 04 March (Jyoti Singh – India Science Wire): The low magnitude and long duration earthquakes in the western coastal region (Dhundhalwadi, Palghar, Maharashtra) started in November 2018 and has produced more than 16,000 earthquakes of magnitude −0.5 to 3.8 which continue to occur even now. This unusual phenomenon caused panic among the people living there but curiosity among the geophysicists.  The researchers installed a seismograph in the region and later they added more seismographs surrounding the reported region of earthquakes. In the study they find that apart from tectonic shifts earthquake could be occurring due to some shallow subsurface processes probably caused by monsoon rains. “We propose that aseismic slip driven by the fluid migration at shallow depth is responsible for the swarm” said Dr. Vineet K. Gahalaut, Senior Principal Scientist, Council of Scientific and Industrial Research-National Geophysical Research Institute (CSIR-NGRI), Hyderabad while speaking with India Science Wire. Swarm is a sequence of generally small earthquakes with no identifiable main shock and they often happen at the same location. They are usually short-lived but they can last for days, weeks or sometimes even months. Two methods were adopted to carry out this research work. The first one is earthquake monitoring. There were 5 seismographs installed around the region of earthquakes. These earthquakes were recorded and located by using standard methods of earthquake location, to analyze their characteristic features. Second, satellite based monitoring of ground deformation were employed known as Interferometric synthetic aperture radar (InSAR) study. The regions of earthquake occurrence and ground deformation coincide. “We started monitoring the earthquake occurrence. We located them very precisely and found that these earthquakes are occurring in a small region of 30 kilometers surrounding the Dhundhalwadi village. They occur at shallow depth of up to 6 km with very clustered epicenters” said Dr Gahalaut. The features of earthquake monitoring, properties of earthquakes and features of deformation, indicate that these earthquakes are caused by some shallow process and probably not by the tectonic process. “The other possibility of they being volcanic in nature, does not arise here. In most likely case, these earthquakes…