Tuesday, May 18, 2010

Hazardous landslide lake

In the Hunza Valley, Pakistan, a large landslide on 4th January this year blocked the valley, with the potential to produce a very large and hazardous lake. The initial landslide killed 19 and displaced 250 families. Since then attempts have been made to construct spillways to limit the volume of the lake, which is now about 20km long and 100m deep in places. 25,000 people have been evacuated by boat from the upper valley. The lake volume increased slowly in the winter, but in May, with the onset of summer and much melt water, the lake has increased rapidly in volume. Evacuation of 18 villages to 30m above river level is underway and warning sirens installed to aid last minute evacuation. The situation is extremely hazardous as the lake may now overflow within days. The exact size of the possible flood is obviously unknown but some estimate that it may exceed the 30m planned evacuation level. A web search for "Hunza Valley Landslide" gives a large amount of extra information.