Nepal was devastated by massive earthquakes and landslides in April and May this year. More than 9,000 people died, and tens of thousands were displaced. But the situation could have been far worse, said an international team of scientists. The main 7.8 magnitude quake on April 25 that struck near the town of Gorkha was expected to trigger tens of thousands of landslides.
Only in 491 lakes in Nepal were affected by landslides
However, only 4,312 landslides occurred in six weeks following the quake, which was far fewer than what would occur after earthquakes of similar magnitude in other mountainous areas. Researchers also feared that the tremors would breach the lakes built up behind the rocky deposits of glaciers, flooding villages and valleys below. Surprisingly, no large floods from overflowing lakes occurred. Scientists surveyed 491 lakes in Nepal, and found that only nine of them were affected by landslides.
Findings of the extensive study were published in the Science magazine, and presented at the Fall Meeting of the American Geophysical Union in San Francisco. Lead author Jeffrey Kargel of the University of Arizona said, “As horrific as this was, the situation could have been far worse for an earthquake of this magnitude.” Why the damages were less than feared was still unclear.
What alleviated the impact of the earthquake?
It could have been because the earthquake, though powerful, was relatively smooth. It shifted the whole Kathmandu region two meters to the south. Another reason could be the rocks in the region were much more powerful than scientists had estimated. Some researchers floated the idea that the rhododendron forests might also have played a bigger role in holding the landscape together.
A second study published in the same journal looked at the geological evidence of historic earthquakes in Nepal, going back about 1,000 years. These quakes were magnitude 8 or bigger disasters. They triggered debris and landslides that completely changed the landscape around them. The team found that Nepal’s second largest city Pokhara is actually built on sediments deposited during landslides following past earthquakes.