A hidden fault lying beneath Bangladesh, Myanmar and eastern India could release a massive magnitude 8.2 to 9.0 earthquake.
The newly discovered subduction zone – buried under miles of river sediment – could killed millions in one of the most densely populated regions of the world. And there are no estimates for when the megaquake will occur.
Scientists don’t know if it’s tomorrow or if it’s not going to be for another 500 years. But what’s sure is that it is going to be cataclysmic.
The newly discovered fault line is situated in the world’s largest delta, where the mighty Ganges and Brahmaputra rivers meet and form. The flow of these two massive rivers deposits a gigaton of sediment every year And thus obscured the geology below the Ganges Delta.
And yes, tectonic plates are colliding beneath the eons worth of sediment. According to GPS measurements, one plate is diving under the other deep beneath the surface in an area encompassing Bangladesh and parts of Myanmar and eastern India – most likely the Indian Plate and a part of the Eurasian Plate.
At the upper layers of the fault, the two plates are stuck together, building up strain that could produce a megathrust earthquake between M8.2 and M9.0 if it ruptures.
About 140 million people live within 60 miles (100 kilometers) of the fault. The country also already faces problems with poor construction. Overcrowding could make it difficult to rescue people who survive the initial quake as streets would be clogged with debris and traffic.
But, right now, it is impossible to predict when this megaquake will hit. The researchers have some evidence of a temblor in 1762 further south from the study area, as well as a quake that may have caused a major river between Bangladesh and Myanmar to switch the direction in which it flowed. Beyond that, the river sediments have buried the geological evidence, and there isn’t historical evidence to provide clues about how frequently these quakes occur.
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.