People salvage wood from house destroyed by the Gorkha earthquake, Nepal.

A large earthquake in 2015 saw more than 600,000 structures damaged or destroyed in central Nepal — and the region is at a risk of an even more powerful quake. Credit: Navesh Chitrakar/Reuters

Geophysics

Why massive earthquakes menace the Himalayas

Area hit by a deadly quake in 2015 is at risk of even greater disaster.

Devastating earthquakes have struck the Himalayan region in recent decades, and an analysis of quake dynamics explains why more ‘big ones’ are probably on the way.

Large Himalayan earthquakes come in two flavours. Some, such as the magnitude-7.8 Nepal quake of 2015, break geological faults along relatively short sections of the mountain range. Others, such as the magnitude-8.7 Assam earthquake of 1950, rupture faults along much longer sections of the Himalayan chain — making these quakes especially powerful and dangerous.

Luca Dal Zilio at the Swiss Federal Institute of Technology in Zürich and his colleagues simulated the physics of these two types of Himalayan quake. They found that friction along the region’s faults and the geometry of the faults underlying the Himalayas help to determine which type of quake occurs.

The team’s analysis shows that, even if smaller ruptures occur along short segments of the mountains, stress builds up along the faults. That accumulated stress eventually triggers an enormous earthquake. The area affected by the 2015 Nepal quake is at risk of an even more powerful quake, the authors say.