When deformation is caused by earthquakes, it is necessary to map the area's size and shape. Especially in Indonesia, which is situated between two main tectonic plates, the examination of risks and hazards to establish the right measures for mitigating and minimizing the risk of earthquakes is vital. Remote sensing is one of the best and most renewable methods for mapping deformation occurrences. InSAR is a remote sensing technique that can be used to analyze deformation. This work employed the DInSAR technique to examine the Sentinel-1 A SLC-IW satellite to investigate the deformation of the Cimandiri Fault in the Palabuhanratu region. Within one of these active faults, a magnitude 4 SR earthquake occurred on September 20, 2022. Comparing satellite photos before and after the earthquake with the DInSAR yielded a large phase difference value centered on the Cimandiri fault line with a phase range of -3,092 to 3,031. It indicates that the Cimandiri Fault is the earthquake's epicenter on September 20, 2022, in Palabuhanratu. The results of an investigation of the displacement value that happens along the line of sight (LoS) fall between 0.105 and 0.672 meters. Due to the incidence angle of the picture observation by satellite, the displacement must be adjusted such that it is perpendicular to the ellipsoid; this is referred to as true vertical displacement. The fixed displacement finding of 0.126 to 0.806 meters suggests that the region surrounding the Cimandiri Fault has risen. As GCP points, we incorporated a number of GPS geodetic data points from the field (near the Bagbagan Cimandiri Bridge, which was the site of the active fault). The outcomes demonstrated that the DInSAR true vertical displacement method can be used to determine surface deformation.

Keywords: Cimandiri fault, Sukabumi, DInSAR, Remote Sensing, Sentinel-1