Nepal earthquake led to fewer landslides

The deadly Nepal earthquake of April this year which killed thousands led to fewer than expected landslides, says a team of international scientists.

The 4,312 landslides that happened within six weeks after the quake were far fewer than what occurred after similar magnitude quakes in other mountainous areas, the study said.

In addition, no large floods from overflowing glacial lakes occurred after the 7.8 magnitude quake, which struck near the town of Gorkha on April 25.

"It was a really bad earthquake - over 9,000 fatalities in four countries, primarily Nepal," said lead author Jeffrey Kargel, senior associate research scientist at University of Arizona in the US

"As horrific as this was, the situation could have been far worse for an earthquake of this magnitude," Kargel noted.

More than 10 satellites from four countries provided images and other data to help volunteer analysts map and report the various geological hazards, including landslides, that followed the earthquake.

Computer models were used to evaluate the likelihood that the downstream edges of glacial lakes would collapse and flood villages and valleys below.

The team also surveyed 491 glacial lakes and saw only nine that were affected by landslides. Satellite images did not reveal any flooding from those lakes.

NASA, the Hakai Institute, the Japan Aerospace Exploration Agency, DigitalGlobe, the Chinese Academy of Sciences and the International Centre for Integrated Mountain Development (ICIMOD) supported the research.

Although the initial research effort was purely humanitarian, the scientists eventually realised they had a huge database that could be analyzed to learn more about geohazards from this and other quakes.

In previous earthquakes in mountainous terrain, many earthquake-initiated landslides occurred from minutes to years after the initial quake.

The study appeared in the journal Science.