Nepal earthquake was less catastrophic than feared

A new study has revealed that the April 2015 Gorkha earthquake that struck Nepal was less intense than might be expected from a magnitude 7.8 quake in the area.

In a region of major faulting and massive tectonic plate collisions, with an especially dense population centered on the country's capital of Kathmandu, seismologists had expected the worst from a major earthquake. And the quake and its major aftershocks did cause more than 8,000 fatalities, 22,000 injuries and hundreds of thousands of collapsed or damaged buildings. But the damage was not as catastrophic as expected, said U.S. Geological Service geophysicist Susan Hough, guest editor of the Gorkha focus section papers.

The world community of earthquake professionals expected an earthquake like this directly beneath Nepal would take a far greater toll on property and lives. So it poses a major challenge to understand and explain the shaking from the earthquake, said Hough.

Hough and others conclude that the shaking was less damaging than expected because of how the Kathmandu valley's "bowl" of ancient lake bed sediments responded, noting that they know that valleys like this greatly amplify shaking from small and moderate earthquakes, but in very large earthquakes, a nonlinear effect kicks in.

The study is published in Seismological Research Letters.