ABSTRACT
This paper addresses coseismic landslides in gentle sandy slopes wherein the displacement exceeded 500 m and claimed hundreds of deaths in destroyed houses. This extent of displacement was substantially greater than what happened during past earthquakes. Aiming at mathematical reproduction of this extreme event, the study reviews the reconnaissance findings and then refers to field surveys. Accounting for the loss of shear resistance under the surface crust, a mathematical theory was developed on the basis of gravity-induced compression of the crust in the slope direction induced by high ground water pressure underneath and loss of shear resistance. Consequently, the passive failure of the crust was found to have shortened the length of the slopes, thus triggering the extreme downslope displacement as occurred in the field.
