Cisadane Fault: Understanding the Potential Seismic Threat to Jabodetabek

The Cisadane Fault, a potentially active fault line stretching across the densely populated Jabodetabek region (Jakarta, Bogor, Depok, Tangerang, and Bekasi), is drawing increased attention from geologists and local authorities. Recent research indicates the fault’s potential for seismic activity, prompting calls for enhanced spatial planning and disaster preparedness. While not currently classified as an active fault in the same category as the Baribis-Citarik system, the Cisadane Fault presents a significant geological consideration for the region.

What is the Cisadane Fault?

Faults are fractures or fracture zones in the Earth’s crust where rocks have shifted or moved.¹ The Cisadane Fault is categorized as a “potentially active fault,” meaning it has cut through Quaternary-aged rocks but lacks a recorded history of significant earthquakes in recent times.¹ This differs from active faults like the Baribis and Citarik, which demonstrate movement during the Holocene epoch and have associated seismic data.

Location and Geological Characteristics

The Cisadane Fault runs roughly northwest to southeast, generally following the course of the Cisadane River.³ It traverses key areas including Bogor, Cibinong, Tangerang Selatan, and Tangerang.³ Geological investigations have revealed clear indications of its activity, particularly in the Rumpin area of Bogor Regency, where the fault appears to have separated Gunung Nyungcung and Gunung Panjang.³, ⁴

Evidence of the fault includes long cracks and fissures on Mount Panjang (also known as Mount Kapur-Ciseeng) in Parung-Rumpin District, Bogor Regency.¹ Researchers have also identified “sag ponds” – small depressions formed by fault movement – along the fault line in Rumpin and Parung, reminiscent of patterns seen with the Baribis fault.³

Research Methods and Findings

The Badan Geologi (Geological Agency) of the Ministry of Energy and Mineral Resources (ESDM) has employed various methods to study the Cisadane Fault, including:

• Analysis of gravity data
• Seismic data to examine subsurface structures
• Geological observations on the surface
• Drone-based LiDAR (Light Detection and Ranging) surveys

The combination of VTOL LiDAR, macro area surveys, and SLAM LiDAR micro-detail analysis has allowed for a comprehensive geological interpretation.²

Implications and Future Considerations

The discovery of the Cisadane Fault underscores the complex tectonic system surrounding Jabodetabek, alongside the Baribis and Citarik faults.³ While the absence of recorded large earthquakes doesn’t negate the risk, the geological evidence indicates ongoing tectonic activity. Authorities are urged to prioritize detailed mapping and further research, particularly given the region’s economic importance and high population density.³

The fault is located approximately 20 kilometers from Jakarta.¹