US to help Bangladesh study earthquake risks

The peaceful Chittagong Hill Tracts — but beneath them lies an earthquake risk Copyright: Flickr/uncultured

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[DHAKA] Earth scientists from Bangladesh and the US have launched a five-year project to identify and study geological features that make this densely populated country prone to earthquakes.

"There is a risk of large earthquakes in Bangladesh," project leader Michael Steckler, research professor at the Lamont-Doherty Earth Observatory, Columbia University, told SciDev.Net.

"The same plate boundary along the Sumatra-Andaman Islands involved in the 2004 earthquake and tsunami continues to the north into Bangladesh," Steckler said.

As a result, Steckler explained, the Chittagong Hill Tracts with their tea plantations, as well as India’s Tripura state in the eastern Himalayas, are part of a zone that is "squeezed and folded over the main fault and has a potential for a large earthquake".

"We want to understand processes controlling the rivers, the tectonics and how they interact with each other," he said.

Syed Humayun Akhter, professor of geology at the University of Dhaka and project member, added: "We want to build a chronology of earthquakes, and improve hazard maps to know what happened earlier and when. Which kind of earthquake can hit the country and, if possible when, so that we can prepare to reduce the losses."

"Records show that in this river deltaic country the course of the Brahmaputra river changed 200 years ago due to an eight plus magnitude earthquake. We want to identify the geological changes that created the present landscape," Akhter said.

The project, funded by the US National Science Foundation, will use a mix of methods: measuring surface movements in the Himalayan foothills, using underground instruments to unearth hidden faults and records of past river movements by boring 250 wells across Bangladesh.

The scientists are also installing instruments to pick up tremors that could be a pointer to hidden faults in a 19-kilometre stretch of sand and mud across the Brahmaputra delta.

Previous studies by Steckler’s team have shown that the region was the site of major temblors and shifts in plates that caused major Himalayan rivers — Brahmaputra, Ganges and Meghna — to shift course suddenly, inundating vast areas.

Rock movements have caused some areas of Bangladesh to sink faster than the others, affecting river course. "If a river is close to switching, then the uplift and subsidence caused by earthquakes may cause it to shift," Steckler said.