Active Fault Cutting Through the Youngest Soil Layer Discovered, Traversing West Java
An active fault zone traversing West Java has been discovered by the Geological Survey Centre (PSG) of the Ministry of Energy and Mineral Resources. This fault is considered crucial because its path passes through areas of vital infrastructure, such as toll roads.
The finding results from mapping activities conducted in Majalengka, Sumedang, and Subang regencies. The primary objective of this survey is to map and monitor potential tectonic disaster risks in those areas.
To ensure data accuracy, PSG Head Edy Slameto directly inspected the research team in the field in October 2025. The activity focused on directly monitoring geological conditions and ensuring the entire survey process ran smoothly.
Edy explained that this monitoring is vital to guarantee the accuracy of field mapping data.
“This activity aims to ensure the smooth implementation of the survey, while also monitoring field geological conditions related to the potential active fault in the region,” he stated, quoted on Saturday (2/5/2026).
The field visit targeted the first location on the Cisumdawu Toll Road at Kilometre 177, Bojongtotor Hamlet, Sirnamulya Village, North Sumedang Subdistrict. This site experienced a landslide at the end of May 2025 with fairly intensive soil subsidence due to weather factors.
Edy outlined that the soil structure around the toll road has complexities requiring extra supervision.
“Initial observations indicate that soil movement in this area is potentially influenced by complex lithological and geological structural conditions, thus requiring further monitoring for risk mitigation around strategic infrastructure like toll roads,” he said.
The second location visited was in Girimukti Village, North Sumedang Subdistrict, where the team found rock exposures indicating the presence of the active Cileunyi - Tanjung Sari fault zone. The survey team immediately conducted documentation and measurements of the fault plane orientation to determine the direction and characteristics of the rock deformation occurring.
The visit on that day then continued to the third location in Cibuluh Village, Ujung Jaya Subdistrict, Sumedang Regency. In this area, rock exposures with broken layers were found, indicating ongoing tectonic activity to this day.
Edy emphasised that the fault zone in the region remains highly active as it is seen cutting through the youngest soil layer.
“The fault section that cuts through to the youngest surface layer indicates that the fault zone in this region is still active and has the potential to cause deformation in the future,” he asserted.