Prediction Studies of Landslides in the Mangan and Singtam Areas Triggered by 2011 Sikkim Earthquake

Abstract

Prediction of field displacements of Earthquake induced slope failure is a common methodology used to estimate the possibility of failure in a ground shaking scenario of interest. Newmark’s algorithm has been used extensively over years to arrive at estimates of ground displacements during earthquakes. This method has been proven to be a reliable technique to predict the spatial distribution of earthquake induced landslides. The current study involves selecting 12 horizontal components of strong motion records from 6 recording stations during the main shock of the Sikkim earthquake of magnitude Mw 6.9 that occurred on September 18th 2011. This data is then used in predicting the spatial distribution of the landslides triggered in and around the Mangan and Singtam areas in the district of North and East Sikkim. Displacement values were calculated by rigorous numerical integration of the acceleration records. These values were then regressed in a multiple linear regression model and the resultant equation was found to be statistically significant with an R2value of 85.7%. These predicted displacement values were compared with the field data of triggered landslides and was found to predict the slope failures with fair amount of accuracy given the nature of the triggered landslides and the climatic conditions during the earthquake event.