The earthquakes in Nepal in April and May this year are now believed to have triggered around 5,600 new landslides, according to the latest analysis by Earthquakes Without Frontiers (EWF).
The research, which EWF undertook jointly with Durham University and the British Geological Society, shows that the earthquakes also caused reactivation of a considerable number of existing landslides.
According to EWF, major or disruptive landsliding is limited to a zone that runs east-west, approximately parallel to the transition between the Lesser and High Himalaya. This zone includes parts of the districts of Gorkha, Dhading, Nuwakot, Rasuwa, Sindhupalchok, Dolakha, Ramechhap, and Khavre.
The new data includes landslides triggered by the 12 May Dolakha earthquake for the first time. In a statement, EWF said that two area of landslides triggered by the Dolakha earthquake overlaps with the eastern end of the area affected by landslides in the Gorkha earthquake. In general, locations that suffered from high landslide intensities after the Dolakha earthquake also suffered from widespread landsliding in the Gorkha earthquake. These areas have suffered damaging levels of shaking in two successive large earthquakes, and must be viewed as having a very high risk of failure during the 2015 monsoon season.
EWF is urging for simple monitoring to be established to ensure the effects of the monsoon on slope stability can be assessed following numerous reports of cracked ground in the affected areas.