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Understanding Active Faults in West Java

The Lembang Fault stretches from Mount Tangkuban Parahu to Cisarua and Lembang, and is known as one of the active faults capable of generating significant earthquakes in Bandung and its surroundings. Previous studies have indicated that this fault can produce moderate to strong earthquakes that may directly impact densely populated areas.

During the field session, Dr. Astyka emphasized that the greatest risk from earthquakes does not solely come from the fault movement itself, but from buildings that do not meet structural standards.

“A house may be damaged, but it should not collapse,” she stated.

She further explained that earthquake-resistant design is a simple yet effective form of mitigation, as outlined in the guidelines issued by the Ministry of Public Works and Housing (PUPR).

“Each wall area of nine square meters must have columns, beams, and a tie beam (sloof). These three elements are essential to keep the building standing even during shaking,” she explained.

The Formation and Activity of the Lembang Fault

During the observation session, Dr. Astyka explained that the formation process of the Lembang Fault remains a topic of scientific debate among geologists. Some researchers associate it with volcanic activity from Mount Tangkuban Parahu, while others point to the strong influence of strike-slip tectonic movement caused by regional stress changes.

“It might have formed due to volcanism in the past, but now its mechanism has changed into a strike-slip fault. The process is complex and still under investigation,” she said.

Students also carried out direct observations of fault morphology, ground fractures, and colluvial deposits at several sites, including Tebing Keraton and Cibodas. These locations exhibit geomorphological features characteristic of active fault movement.

The Link Between Earthquakes and Volcanic Activity

Furthermore, Dr. Astyka highlighted the connection between tectonic earthquakes and volcanic activity in West Java. She explained that earthquakes can trigger increased volcanic activity when magma is already in a critical state.

“If a volcano is in a critical condition, an earthquake can act as a trigger for eruption. That is why understanding the relationship between fault activity and volcanism is crucial,” she explained.

Building Scientific Awareness for Disaster Mitigation

This field excursion served as a valuable learning platform for graduate students to understand the relationship between geodetic data, tectonic dynamics, and disaster mitigation in a real-world context. Through hands-on observation, students were able to see how theoretical knowledge is applied to identify geological hazards within the community.

Through this activity, ITB reaffirms its commitment to developing skilled human resources in geodesy and earth sciences, while fostering scientific awareness and disaster preparedness among academics and society.

Reporter: Merryta Kusumawati (Geodesy and Geomatics Engineering, 2025)