Nature sounding alarms: 25 earthquakes in the last 2 days at Andaman & Nicobar Islands, residents & authorities alert
Repeated seismic activities could induce tsunami-like situation.
In the wake of a dozen seismic events reported in the Andaman and Nicobar Region on Monday and Tuesday, a depth distribution analysis of the earthquakes has suggested that the events were mostly concentrated at mid-crustal level and along back-arc, the National Center for Seismology (NCS) said.
The Andaman and Nicobar Islands is a high-seismic zone and is prone to earthquakes. The entire island chain is also susceptible to tsunamis both from large local quakes and also from massive distant shocks. No warning system is presently in place for any of the islands in this chain.
There were 25 seismic events of magnitude range between 3.8 and 5 reported in the region in the past two days, and the NCS analysis found the epicentre locations of these earthquakes between the West Andaman Fault and Andaman Spreading Ridge.
“The continuous occurrences of earthquakes in the magnitude range varying between M:3.8 and M:5.0 suggest the release of accumulated seismic strain due to the perturbation of the stress level in the areas of the subducting Indian plate and its surroundings,” the analysis said.
The back-arc basin in the Andaman Sea region has experienced several (seismic) swarms as well aftershocks activity in the past five decades, with varying depth and magnitude. “The present earthquake activity is not unusual and witnessed such activity in the past,” the analysis said. Three major phases of swarm activities during 1983-1984, 1993 and 2005, and major aftershocks activity of 2009-2010 has been reported.
The Andaman & Nicobar represents a complex topography comprising of a volcanic arc system, back-arc spreading ridge, several sea-mounts and faults. The region has been placed in Zone-V, the highest level of seismic hazard potential, according to the seismic zonation map of India by Bureau of Indian Standards published in 2016.