Lineament Trend Analysis for Designing of Fault Deformation Monitoring Network in the Sermo Reservoir Area, Yogyakarta, Indonesia

Abstract

The Sermo Reservoir plays a vital role in the livelihood of the surrounding community. However, based on the geological map, a fault crosses the reservoir and possibly through the dam body. Therefore, disaster needs to be mitigated by monitoring the deformation of both the fault and the dam body. Deformation monitoring network design needs to consider the accuracy, reliability, and sensitivity in detecting and measuring any displacement. Geological conditions affect the sensitivity of the network. This research aims to analyze the geological structure based on the lineament interpretation of the deformation monitoring network design of the fault. The study was conducted by interpreting lineaments using the Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) image with 30 m resolution and then representing the lineament patterns with a rose diagram. The lineament analysis was related to the rock formation of areas surrounding the Sermo Reservoir. Furthermore, the deformation monitoring network will be designed considering the geological phenomenon resulting from lineament analysis and other factors used in previous research, such as the distance and direction of the control point from the fault. From the lineament analysis, initial information showed that the fault was estimated in the direction of northwest-southeast and may be active. Deformation monitoring stations should be established along the fault plane, in both the right and left sides, and within various distances. The stations should be evenly distributed to cover the areas around the reservoir, the area outside the reservoir but still within the fault area, and the area outside the reservoir and the fault. The distribution of the stations should also form a transverse baseline to the fault.