KOCHI: Kerala continues to be the most earthquake-free zone compared to other southern states — Tamil Nadu, Andhra Pradesh and Karnataka. This is despite the fact that the recent intense rainfall, quarrying and unscientific construction activities have increased the risk of induced earthquakes in the state.A report submitted by the Ministry of Earth Sciences in Parliamant has revealed that no major tremors were reported in Kerala during the three-year period between July 2016 and June 2019, while Tamil Nadu, Andhra Pradesh and Karnataka experienced an earthquake each during the said period.
Cochin University of Science and Technology (Cusat) Department of Marine Geology and Geophysics head P S Sunil said though Kerala is in a comparatively safe zone when it comes to earthquakes, the recent climate changes can bring in different kind of seismic activities that could result in earthquakes.
“There are three types of earthquakes -- inter-plate, intra-plate and induced. In Kerala, the chances of induced earthquakes are more compared to the other two. The possibility of induced earthquakes has gone high after the recent heavy downpour and floods. Even storing of high water levels in dams can also result in earthquakes.
The water seeps through the cracks on earth and acts as lubricants, resulting in plates to move causing earthquakes,” he said. “The high static pressure from the water in the dams also result in loose crustal plates moving. This phenomenon is called reservoir induced earthquakes,” said Sunil.
Main cause of earthquakes in India
Studies by scientists show that the main cause of earthquakes in India is due to Indian plate moving in the northeast direction at a rate of about 52 mm/year and its collision with Eurasian plate in the north and with Sunda plate in the east.
Bureau of Indian Standards, based on scientific inputs like past intensity records and ground motions from a number of agencies, has grouped the country into four seismic zones -- Zone-II, III, IV and V. Of these, Zone V is the most seismically active region while zone II is the least.
Zone VI
Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Rann of Kutch in Gujarat, part of North Bihar and Andaman & Nicobar islands.
Zone IV
Remaining parts of Jammu & Kashmir, Himachal Pradesh and Uttarakhand, Union Territory of Delhi, Sikkim, northern part of Uttar Pradesh, Bihar and West Bengal, parts of Gujarat and small portions of Maharashtra near the west coast and Rajasthan.
Zone III
Kerala, Goa, Lakshadweep islands, remaining parts of Uttar Pradesh, Gujarat and West Bengal, parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhatisgarh, Maharashtra, Orissa, Andhra Pradesh, Telangana, Tamilnadu and Karnataka.
Zone II
Parts of Rajasthan, Madhya Pradesh and Maharashtra, Parts of Odisha, Andhra Pradesh, Telangana, Karnataka and Kerala.