Detection of Landslide Plane by Using Refraction Seismic Tomography Method

An application of refraction tomographic method in order to identify a predicted landslide’s plane is presented. This method is applied to detect the existence and the geometry of possible landslide’s plane that is situated in a Seling Village, Kebumen City — Indonesia. This area experienced several episodes of landslide type of creeping several years ago. Although it has been observed that the displacement of the most upper part of surface is only several centimeters per years, but there is a tendency that bigger landslide could be occurred in the future.

The seismic data was acquired on the surface that has a total length of about 150 m. Twelve shots and 24 geophones are planted on the seismic line that is perpendicular to the predicted strike of landslide’s plane.

The result shows that the most upper part of surface has low P-wave velocity values. Higher P-wave velocity layer is situated below this layer. The plane between those layers is then interpreted as possible landslide’s plane. The result of this investigation is a P-wave velocity section, which correlates well with almost all available a priori data. Several resolution tests are conducted in order to increase the certainty degree of tomographic results.