Identification of surface layer structure using seismic refraction for landslide mitigation in Tandikek region, West Sumatra Indonesia

Abstract

The landslide in West Tandikek Nagari, Padang Pariaman Regency, in 2009 was triggered by an earthquake that claimed hundreds of lives and buried several villages. Losses caused by landslides in West Tandikek Nagari should be minimized by studying the causes and symptoms of landslides. Disaster mitigation efforts must be carried out to anticipate and mitigate losses due to landslides so that the impacts can be overcome. These disaster mitigation actions can be carried out by identifying areas with the potential for landslides based on the subsurface structure in West Tandikek Nagari. This type of research was descriptive. Data collection is carried out directly using the Sysmatrack-MAE Seismograph, 12 geophones, GPS, gauges, trigger cables, geophone cables, and sources in the form of a seismic hammer and iron plate with the seismic refraction method. Data processing to obtain velocity and depth values for each track below the surface with the seismic refraction method and for interpretation used the Time-Term Inversion. The results obtained for the first layer are dominated by sand and soil materials. The second layer is dominated by alluvium gravel sand and clay. The relatively hard layer of clay and alluvium makes it difficult to store and pass water. This will cause water from the top layer to accumulate in the rock, which makes the rock slippery. This slippery clay layer will act as a subsurface for the weathering material above it to move out of the hillside