GNSS constraints on the Jakarta fault, Indonesia: Resolving slip rate and seismic hazard potential

The characteristics of the active faults in the region around the megacity of Jakarta are poorly understood. This study investigates slip rate of the Jakarta Fault using new GNSS data obtained from campaign measurements conducted between 2019 and 2023. This is a recently discovered active fault forming part of the broader Baribis Fault system that runs across most of northern Java. The Jakarta Fault cuts across the southern portion of Jakarta, a city with over 32 million people in the metropolitan region. In this study, we apply a 2-D screw dislocation model to the north-south component of the GNSS velocities, which are projected onto a profile perpendicular to the approximately east-west trending fault. Our analysis estimates a fault slip rate of 3.2 mm/yr, with a locking depth of 7.2 km and a dip angle of 63°. Previous studies have estimated the fault length to be approximately 50 km, with a return period of around 210 years. By combining this information with our findings, we estimate that a potential earthquake of magnitude between 6.49 and 6.54 could occur on the fault. Our research highlights the active deformation occurring along the Jakarta Fault, emphasizing the urgent need for greater attention from stakeholders, as an earthquake of this magnitude could pose significant seismic risks to the Jakarta region.