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Locked fault under South Asia could host megaquake and risk millions of lives

12 Jul 2016

A new study has suggested a locked megathrust fault hidden underneath Bangladesh and eastern India could cause a cataclysmic earthquake measuring a moment magnitude 8.2 to 9.0. Scientists estimate that such a massive quake in one of the most densely populated regions in the world would potentially risk the lives of more than 140 million people.

Published in Nature Geoscience yesterday (11 July 2016), co-authors Assistant Professor Emma Hill and Senior Research Fellow Dr Lujia Feng from the Earth Observatory of Singapore who participated in the study conducted by an international team led by Professor Michael Steckler of Lamont-Doherty Earth Observatory (USA), explained that they now have new evidence of increasing strain in the subduction zone, where the Indian subcontinent has been slowly diving into Asia. This tectonic strain, they believe, has been accumulating for at least 400 years beneath Bangladesh and is a hint that an earthquake is building up its energy.

“The key finding of this study is a giant earthquake with a magnitude greater than 8.0 may be building up beneath Bangladesh,” Dr Feng said. “As this region has enormously thick (12-16 km) sediments washed away from the Himalayas, the effect of such an event could be magnified, causing destruction as huge as the 2015 Nepal earthquake, or worse.”

According to Dr Feng, scientists have long suspected and debated this hazard. However, there was no data and a model to support the hypothesis. Now that this study has provided them with the much-needed data and model from a GPS network in Bangladesh, combined with other GPS measurements from Myanmar and northeast India, they can make an estimate on the size of the earthquake.

Dr Feng went on to emphasise that this study does not aim to forecast the imminence of the impending earthquake as researchers do not know if and when the fault will give way and whether the fault will be slipping in a single event or a series of events. But, what this study has done is to show, for the first time, strong evidence that a lot of strain is accumulating possibly as a result of a locked subsection zone under Bangladesh and the neighbouring regions. 

“Therefore, it is important for the community’s safety in the future that we continue monitoring this region using modern instruments like GPS and seismometers, etc.,” said Dr Feng, “and to start educating the public on the potential hazards so that they can be better prepared.”