“But we can definitely see it building”, Steckler said.
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However, researchers report in the journal Nature Geoscience that subduction is now taking place below Bangladesh, and it represents an “unprecedented hazard in one of the most densely populated regions of the world”. Scientists used Global Positioning System data collected since 2003, and say that tectonic plates are converging at a rate of 13-17mm per year “on an active, shallowly dipping and locked megathrust fault”.
Scientists have been tracking tiny ground motions with Global Positioning System since 2003.
We have always been warned that Bangladesh is at high risk of getting hit by a major quake and over the past year, and the city has been experiencing minor quakes from time to time.
Citing data collected using Global Positioning System devices since 2003, the paper states that measurements found convergence of tectonic plates at a rate of 13-17mm “on an active, shallowly dipping and locked megathrust fault”. “We need more data”, he said.
In the low-lying, waterlogged country of Bangladesh, the mighty Ganges and Brahmaputra rivers meet and form the world’s largest delta, eventually draining into the Bay of Bengal. Combined with existing Global Positioning System data from India and Myanmar, the measurements show that much of the resulting strain has been taken up by several known, slowly moving surface faults in Myanmar and India.
Steckler believes that the 17 million people who live in the Dhaka region of the country are most at risk.
Assuming movement has been steady over the last 400 years, enough strain should have built up for the zone to jump 5.5m all at once. If strain has been building longer, it could be up to 30 meters, or nearly 100 feet. However Steckler said that it is impossible to predict when a quake might happen.
In Bangladesh, shoddy, unregulated building construction abounds, and heavy industries, power plants and structures at natural gas sites would likely be destroyed, the study’s authors said.
Scientists knew of the plate boundary in and around Bangladesh but many assumed it to be sliding only horizontally near the surface, where it sometimes causes fairly large but less damaging earthquakes in areas that are not as densely populated. “In Dhaka, the catastrophic picture will be beyond our imagination, and could even lead to abandonment of the city”.
Meanwhile, researchers in and around Bangladesh are persevering in assessing the threats looming over the country.
To better characterize the region’s risk, the team is building a more detailed map of the shape of the fault, as well as looking at historical tsunami data to understand how often megathrust earthquakes occur, Steckler said.
Scientists in the region are now trying to do just that, with a team from New Mexico State University planning to deploy 70 seismometers across Myanmar next year.
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“We don’t have a good idea of its geometry, we don’t know how far it goes down”, Ni said. The flow of these two massive rivers deposits a gigaton of sediment every year, the researchers said.
