HYDERABAD: The earthquake that hit the west coast of Indonesia on Wednesday is ‘not uncommon’, says a city-based scientist. “It is not out of ordinary for seismic activity above the magnitude of 8 to occur once in a year on an average. This year, it is the second such event. Between 2000 and 2012, the year 2007 saw four such big earthquakes. Except for 2002 and 2008, at least one quake per year is the norm,” says Dr D Srinagesh, seismologist at the National Geophysical Research Institute (NGRI).The quake which sent tremors in the coastal cities of Andhra Pradesh struck at a distance of 2000 km from Vijayawada and 20 km below the sea. The Indian National Centre for Ocean Information Services in Hyderabad, which measured the height of the waves in real-time, reported 0.1 to 0.2 metre high waves along the coast of Andaman and Nicobar islands.“We have a network of 16 seismic stations in Andhra Pradesh, nine in Northeast, 10 in the Indian peninsula and nine in Western India. Sumatra and Indonesia are known to be regions prone to big earthquakes. However, Hyderabad is safe,” said the scientist.Working on the seismic hazard assessment of the Indo-Gangetic plain, he says the phenomenon of stress load and reload cause patches of faults to break out frequently, leading to earthquakes. “It is as though the plates are releasing their stress and when that happens there is another plate which gets loaded with the stress, which it releases at a different location.”Dr Srinagesh says that except for 2007 when only nine earthquakes greater than magnitude 7 were recorded, the number averages at two digits. “If we take an average of earthquake measuring up to a magnitude of 7 or more, there are 13 to 14 occurrences per year. Earthquakes cannot be predicted, but the hazard can be mitigated,” he says.
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