Safety factor analysis of landslides hazard as a result of rain condition infiltration on Buyan-Beratan Ancient Mountain

Disaster of soil movement from NDMA (National Disaster Management Authority) of Indonesia mention from 2003-2017 shows the increasing. Investigation of potential ground motion based on sampling data of boring test on slopes along the Denpasar-Singaraja road around Gitgit Village which provides the greatest threat to settlements and public facilities. This research is expected to show the influence of rainfall on slope stability. This research is expected to show the influence of rainfall on slope stability. Furthermore, safety factor analysis based on daily rainfall data and numerical analysis was assisted by SLOPE/W and SEEP/W software tools. The analysis was carried out using a normal, heavy, and very heavy rain model. Safety factor declined after the 3^rd day of rain after that the safety factor dropped to the 6^th day with a safety factor 1.141 indicating the condition to be critical. The result shows the effect of rainfall decreasing safety factor after the second day of rain and the fourth day of safety factor shows a value of 1.003 where the slope is in a critical condition leading to failure, these results can be used to make early warning system of landslide hazard.