Another earthquake of 4.5 magnitude on the Richter scale struck the Bay of Bengal near the Andamans, about 1,200 km from Chennai, on Wednesday. This came a day after the city felt the tremors of a moderate earthquake that hit the region.
The earthquakes posed no threat to Tamil Nadu, officials of the India Meteorological Department (IMD) and geology experts clarified.
According to IMD, an earthquake of such magnitude is common in the Andaman region and such low-intensity quakes occur frequently.
Tremors of quakes in faraway regions that were felt in the city in the past two decades
Some quakes with epicentres in Tamil Nadu
Chennai did not report tremors on Wednesday.
‘No reason for panic’
N. Puviarasan, Director, Area Cyclone Centre, Regional Meteorological Centre, said there was no need to panic about possible tsunamis as earthquakes in the Andaman region were of low intensity and occurred at a depth of 10km.
The region falls under the subduction zone where boundaries of the Indian and Burmese tectonic plates meet and one plate moves under another.
Last year, the region witnessed nearly 162 such occurrences. “As the zone is active and releases energy through low intensity earthquakes, no major earthquakes can happen,” he added.
L. Elango, professor, Department of Geology, Anna University, said Tamil Nadu had been grouped under zone III seismic zone, which was relatively less vulnerable to earthquakes, by the Bureau of Indian Standards. Chennai experienced tremors as it is close to the plate boundary.
“The State is less prone to powerful earthquakes when compared to northeastern India, Kashmir and Gujarat that fall on Indian plate boundaries,” he said.
Experts note that though both the earthquakes were centred in the Bay of Bengal, they occurred due to different reasons.
Weather blogger R. Pradeep John, who runs the Facebook page Tamil Nadu Weatherman, said Tuesday’s earthquake was intraplate and rare. Wednesday’s quake was along the plate boundary. The region along the plate boundary tends to experience earthquakes frequently.
Chennai has experienced tremors due to powerful earthquakes that have occurred in faraway regions like the ones in 2012 and 2009. As there are no major plates running close to the State, it has experienced only low intensity earthquakes in the past. Mr. John also cited tremors that occurred in 1966 with Tambaram as the epicentre.
The Hindu had reported in April 1966 that mysterious explosions were experienced in Tambaram and its neighbourhood for a fortnight.
The Regional Meteorological Centre had issued a bulletin that Meenambakkam observatory had recorded three tremors at a distance of 11 km from the observatory.