Impact of Nepal earthquake more severe due to abnormally thick layer of snow

Researchers from Utrecht University and Nagoya University in Japan have found that the damage caused by the earthquake in Nepal in 2015 was exacerbated by an abnormal amount of snow. They published their findings in the open access journal Natural Hazards and Earth System Sciences.

Four times more powerful

The Gorkha earthquake in April 2015 destroyed large parts of central Nepal and resulted in nearly 9,000 deaths. One of the affected areas was the Langtang Valley, where approximately 350 people lost their lives. A recent study conducted in Nepal by Utrecht University and Nagoya University shows that much of the damage was not actually caused by the earthquake itself but by avalanches, which led to this disaster due to excessive snowfall. The new study shows that the avalanche was four times more powerful than originally thought.

Once in a hundred 100 years

Led by Dr Koji Fujita from Nagoya University in Japan, researchers from the International Centre for Integrated Mountain Development (ICIMOD), including hydrologist Dr Walter Immerzeel from Utrecht University, collected meteorological data and drone images of the area. The analyses showed that such a quantity of snowfall occurs only once in a hundred years. "About three quarters of the material that the avalanche deposited on Langtang consisted of snow," says Fujita. "The remaining quarter consisted of glacier ice and debris."

An artificial debris-covered glacier

Six months after the disaster, the Langtang Valley is still covered with debris. “An artificial debris-covered glacier has developed in the valley, which won’t melt away quickly," says Walter Immerzeel. “Due to the rocks, stones and debris which were deposited on top of the ice during aftershocks, the ice can’t melt, and it might be years before the glacier disappears from the valley.”

Full image

Publication

Fujita, K., Inoue, H., Izumi, T., Yamaguchi, S., Sadakane, A., Sunako, S., Nishimura, K., Immerzeel, W. W., Shea, J. M., Kayastha, R. B., Sawagaki, T., Breashears, D. F., Yagi, H., and Sakai, A.: Anomalous winter-snow-amplified earthquake-induced disaster of the 2015 Langtang avalanche in Nepal, Nat. Hazards Earth Syst. Sci., 17, 749-764, doi:10.5194/nhess-17-749-2017, 2017.

Contact

Dr. Walter Immerzeel, Utrecht University, W.W.Immerzeel@uu.nl, +31 30 253 6865