How close are we to the next big Himalayan quake?

The next big quakes along the Himalayan ranges should happen approximately 500 to 1,000 years after the most recent event at each location. For some locations here, that time has already passed; for others it is 1,000 years from now, according to a new study.

Quoting Steven Wesnousky, a paleoseismologist at the University of Nevada, Akash Kharita of IIT-Roorkee writes that the finding is based on a study of earthquake data at 30 sites along the Himalayan arc.

Build quake-resistant infra

Wesnousky’s study has been published in the Seismological Research Letters. “When will (these earthquakes) occur? No one can tell exactly,” says he. However, damage can be minimised by building quake-resistant infrastructure and drawing up emergency response plans.

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“Check the National Disaster Management Authority’s website for how you can be ready. Remember that during an earthquake if you are outdoors, get into the open and get away from anything that might fall on you. If you are indoors, drop, cover and hold on,” Wesnousky says.

1950 Assam quake sets trend?

If Wesnousky is right, the arc may be ready to rupture in multiple locations, which could result in a series of great earthquakes similar to a recent earthquake sequence in Alaska where damaging earthquakes occurred in 1906, 1946, 1957, 1964 and 1965.

The 1950 magnitude -8.7 earthquake in Assam on August 15 may have begun a similar sequence in the Himalayas, says Wesnousky. The quake was destructive in both Assam and Tibet, killing 4,800 people. It was also notable for the loud noises reported throughout the region.

Also read: A major Himalayan quake is coming. But when?

“Sufficient stress has been accumulating in the Himalayas along the Main Himalayan Thrust for years,” Wesnousky adds. He says this pent-up stress could produce a sequence of mega thrust earthquakes, with multiple events greater than magnitude 8.5 (M8.5).

Warrants deeper research

“As horrible as it sounds, we should expect great magnitude 8.5 (or larger) mega thrust earthquakes to occur again in the Himalayas,” says Roland Burgmann, professor at the University of California, Berkeley, who was not part of this study.

But Roger Bilham, a research scientist at the University of Colorado, Boulder, US, says that a weakness in studies like Wesnousky’s is that available data only record one large earthquake. Researchers may want to see the paleoseismic record extended back 10,000 years — multiple earthquake cycles — at each location to determine the intervals between great quakes.

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