Reduction of the stability of pre-existing landslides during earthquake

摘要

Seismic slope stability analyses of six different landslides were performed for different horizontalpeak ground acceleration coefficients. Movement of two of those landslides after the “2004 Niigata ChuoEarthquake” had caused huge damage by blocking the stream. Remaining four landslides were not movedconsiderably during “2007 Niigata Oki Earthquake” although they were located close to the epicenter. Thestudy result shows that if the 2007 earthquake would have been occurred in rainy season as in the case of the2004 Niigata earthquake,many pre-existing landslides could move and cause excessive damage. The study resultrecommends the concerned authorities to conduct seismic slope stability analysis of pre-existing landslides forthe critical situation and prepare the protective measure for those situations.