Ground Deformation at Lokanthali, Kathmandu, Due to the M_w 7.8 2015 Gorkha Earthquake

摘要

The M_w 7.8 2015 Gorkha Earthquake left close to 9,000 people dead, 22,000 people injured and a loss of properties over $5B. One among the major disasters triggered by this earthquake was landslides. Moreover, many buildings, including several of modern construction, collapsed in Kathmandu due to the earthquake shaking. One of the widely covered damages was the ground failure at Lokanthali, along Araniko Highway in Kathmandu. This failure affected a 250 m long stretch of the highway with vertical movements of more than a meter and lateral displacements on the order of 0.5 m, and also seriously damaged dozens of buildings. To identify the causes of ground failure, the authors performed a site investigation including subsoil exploration with field Vane Shear Testing and Swedish Weight Sounding equipment, as well as topographical mapping. Additionally, numerical analyses were also performed to understand the seismic vulnerability of the site. Our study revealed that Lokanthali was affected by seismically induced landslide movement although the site has gentle slopes and the Gorkha earthquake produced relatively moderate ground accelerations at this location.