The Cimandiri Fault Zone West Java (Indonesia) Revisited - An Integrated Structural, Seismic, Geodetic and InSAR-Derived Deformation Reassessment

The Cimandiri Fault Zone (CFZ) is an active 100 km long fault system in western Java, Indonesia. Its location along the Indo-Australian–Eurasian plate boundary and proximity to densely populated areas make it a major seismic hazard. We present an integrated reassessment of the CFZ’s structure, seismicity, and crustal deformation to address unresolved questions about its geometry. Our study integrates a comprehensive review of past work, new geological field mapping, analysis of local seismicity, and geodetic observations from ongoing GNSS campaigns, complemented by an ongoing LiCSBAS InSAR time-series analysis, to better constrain the fault’s characteristics.

Preliminary results indicate the CFZ’s structural configuration is more complex than previously assumed. Although historically identified as predominantly sinistral (left-lateral) strike-slip, the fault actually comprises multiple segments with oblique and reverse-slip components. Recorded seismicity (e.g.1982 M5.5 and 2000 M5.4 earthquakes) confirms the CFZ’s activity and underscores its capacity to generate damaging earthquakes.

Previous GNSS-based studies have reported regional horizontal deformation on the order of 1–2 cm/year across western Java, with inferred slip rates of 4–5 mm/year along segments of the Cimandiri Fault Zone, indicating active strike-slip deformation and strain accumulation. We integrating geological, seismic, and geodetic insights and refining the CFZ’s segmented fault model and slip estimates that offer an improved basis for seismic hazard assessment and disaster risk reduction in West Java, ultimately enhancing regional resilience. Ongoing InSAR analysis will further give supporting results for the interseismic strain distribution along the CFZ and provide a forward look at evolving deformation patterns. The multidisciplinary approach yields new insights into the behavior of this active fault that will highlight how the combination of structural, seismological, and geodetic data enhances understanding of seismic hazards in complex tectonic settings.