Bangladesh could be hit by a 9.0 magnitude MEGAQUAKE: Huge collision of tectonic plates puts 140 million people at risk

Geophysicists have discovered a subduction zone underneath the region

They believe pressure may have been building for more than 400 years

Beyond the initial quake a large seismic shift could move land below sea level and change the course of rivers in the region

Pressure building up underneath Bangladesh could unleash a massive earthquake affecting 140 million people in one of the world's most highly populated areas, experts have revealed.


Scientists believe that the fault line between two tectonic plates under the world’s largest river delta could rupture, resulting in widespread flooding and changes to the paths of rivers which supply the densely populated region.


The team estimates the strain has been steadily building in the rocks for at least 400 years and could release a quake of up to 9.0 in magnitude below the one of the most densely populated countries in the world.

A team of geophysicists in the US identified a region under the Indian subcontinent where one of the tectonic plates is slowly being forced underneath another – called a subduction zone.


Similar subduction zones were responsible for the enormous quakes which caused the Tsunami in 2004 as well as the Tokohu quake off the coast of Japan in 2011, which resulted in the Fukushima nuclear reactor disaster.


Scientists have long known that a boundary between plates exists under the region, but it was thought to have been close to the surface, where it would cause shallow, less devastating quakes confined to more remote regions.


However, the discovery of a subduction zone indicates that one region of the plates is unable to budge, so the stress is building. They warn a quake could potentially occur deep below the surface and would give little, if any, warning of an impending shift.









THE SAN ANDREAS FAULT


On the other side of the world, researchers believe California is ill-prepared if the 'big one' hits.


The San Andreas system in Northern California consists of five major branches with an overall length of about 1,25O miles.


Experts say there is a 99 percent chance of a magnitude-6.7 earthquake or larger in the next 30 years in California because of the number of fault lines in the region.


The San Andreas Fault that forms the tectonic boundary between the Pacific Plate and the North American Plate is the biggest.


‘Some of us have long suspected this hazard, but we didn’t have the data and a model,’ said Michael Steckler, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory and lead author of the study.


He added: ‘Now we have the data and a model, and we can estimate the size.’


‘We don’t know how long it will take to build up steam, because we don’t know how long it was since the last one. We can’t say it’s imminent or another 500 years. But we can definitely see it building.’


The entire region is seismically active, with the collision between a giant tectonic plate forcing its way northwards resulting in the formation of the Himalayas. Occasionally this seismic shoving gives rise to earthquakes, such as the 2015 quake in Nepal which claimed 8,000 lives.


According to the team, enough strain may have accumulated for the Earth to shift horizontally by about 5.5 meters (18 feet), but could potentially shift up to 30 meters (100 feet) if the strain has been building longer than four centuries.


Such an enormous shift would also cause the ground to move vertically, but to a much lesser extent, say the team. But the impact could be far reaching,opening up new areas to flooding and changing the course of rivers in the region.


The findings arepublished today in the journal Nature Geoscience.