Warning for Nepal: April Earthquake Didn’t Unleash All Its Energy

Post 4765

Warning for Nepal: April Earthquake Didn’t Unleash All Its Energy

The devastating earthquake that struck Nepal in April released only a fraction of the energy still trapped in the underlying fault, meaning the area has the potential to host another large earthquake in the future, researchers say.

In April, a magnitude-7.8 earthquake struck 50 miles (80 kilometers) northwest of Nepal’s capital of Kathmandu, killing more than 9,000 people and flattening entire villages. Geologists thought this quake originated on the Main Himalayan Thrust.

“The Main Himalayan Thrust is a fault that has produced large earthquakes every century or so,” said study lead author Jean-Philippe Avouac, a geophysicist at the University of Cambridge in England. “Nepal lost two kings to these quakes, one in 1255, another in 1344. The last large earthquake to hit Nepal, a magnitude-8.2 earthquake in 1934, destroyed Kathmandu, as did a magnitude-7.6 earthquake in 183.” [Nepal Earthquake Photos: Odd Effects of Kathmandu Temblor]

Combining two Sentinel-1A radar scans from 17 and 29 April 2015, this interferogram shows changes on the ground that occurred during the 25 April earthquake that struck Nepal.

Near the Tibetan Plateau

Combining two Sentinel-1A radar scans from 17 and 29 April 2015, this interferogram shows changes on the ground that occurred during the 25 April earthquake that struck Nepal. An overall area of 120×100 km has moved – half of that uplifted and the other half, north of Kathmandu subsided. Vertical accuracy is a few cm. (Image Credit: Contains Copernicus data (2015)/ESA/Norut/PPO.labs/COMET–ESA SEOM INSARAP study)

Scientists think major earthquakes happen at faults or cracks in the earth when rocks that are locked in place slip, releasing accumulated stress in a catastrophic manner. To investigate how much energy of the Main Himalayan Thrust had been unlocked during the April quake — and how much had not, holding the potential to burst with a major earthquake in the future — seismologists analyzed the effects of the disaster using seismometers on the ground and radar images taken by satellites in space.

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