EARTHQUAKE-INDUCED LANDSLIDE STABILITY ANALYSIS OF THE LAS COLINAS LANDSLIDE IN EL SALVADOR

摘要

The January 13, 2001 earthquake (M7.6) off the coast of El Salvador triggered widespread damaging landslides in many parts of the country. The Las Colinas landslide, located in Balsamo Ridge west of San Salvador, caused the greatest loss of life in a single location from the earthquake. The pre-earthquake and post-earthquake seismic stability analysis of the Las Colinas slope is studied using the limit equilibrium and finite element methods in this paper. The safety factor of the pre-earthquake slope was likely over 1.50 based on the low groundwater level, which was noted by local residents prior to the January 13 earthquake. The slope failed as the horizontal earthquake coefficient, kc, reached between 0.18g and 0.31g depending on the failure analysis methods (i.e. circle and trial surface methods) and the low soil strength assumed. The safety factor of the post-earthquake slope falls in a range from 1.851 at low water saturation to 1.337 when fully saturated. As compared with the pre-earthquake slope, the stability is about 8 percent higher for the post-earthquake slope.