|The Badakhshan landslide, showing its extreme mobility|
Photo by Blal Sarwary as posted on Dave Petley's Landslide Blog
Links to sources are in adjacent text.
On his Landslide Blog, David Petley has drawn from the Twitter feed of Bilal Sarwary, a BBC reporter on the spot where the landslide occurred in the Argo District of Badakhshan Province in Northeast Afghanistan was a failure in deposits of windblown sand (loess) after a period of heavy rainfall and flooding. With no hope of recovering the bodies of victims, Afghanistan has declared the site a mass grave and dedicated Sunday as a day of national morning.
While Petley conservatively says that "is now believed to have killed at least 350 people," the news media are reporting as many as 2000 deaths. Even the conservative value makes it the worst landslide to date in 2014, and the death toll is bound to increase as reports of missing people come in. There are about 4,000 survivors in need of care. The landslide is believed to have occurred in two phases, separated by enough time that people from adjacent villages had arrived to help with rescue efforts, only to be caught by the second landslide. Note that the Oso landslide in the U.S. two months ago also had two phases, but these were separated only by about 4 minutes.
|Location of the landslide|
From Cnn.com here
|Map of location of loess deposits from here.|
|Macropores in loess, Tianshui, Gansu Province|
from the Zhang reference cited at *
ASIDE: Although there appears not to have been an earthquake that triggered the Afghanistan landslide, it is worth keeping in mind that this huge region in Asia is subject to major earthquakes, which commonly trigger landslides if they are greater than M6, and wet weather.
On December 16, 1920, the M7.8 Haiyuan earthquake (also called the 1920 Gansu earthquake and estimated by some to have been as high as M8.7) killed at least 100,000 people, probably double this number according to the USGS. A Chinese paper in existence at the time Ningxia Daily, reported 240,000 killed. Strong trembling occurred for 10 minutes. Reportedly, 500,000 houses and cave dwellings collapsed.* The shaking occurred over an area of about 50,000 square kilometers, most of which is covered by loess. The landslides triggered by the earthquake blocked rivers and buried villages and farmlands.
*Zhang, Zhenzhong, Geological disasters in loess areas during the 1920 Haiyuan earthquake, China, GeoJournal, 36 (2/3) 269-274, 1995.
Zhou, Jin-xing, Zhu Chun-yun, Zheng Jing-ming, Wang Xiao-hui, Liu Zhou-hong, Landslide disaster in the loess area of China, Journal of Forestry Research 13(2), 157-161, 2002.