ACTIVE FAULT DATABASE FOR THE NORTHWESTERN BRANCH OF THE EAST AFRICAN RIFT SYSTEM (EARS)

The Northwestern Branch of the East African Rift System (EARS) is a tectonically active region characterized by significant earthquakes and active plate motions that form numerous active faults. Earthquake magnitudes typically range from 3.0 to 5.5 Mw, with larger events occasionally producing magnitudes above 6.0 Mw. We compile a database of active faults in the NW branch of EARS using an integrated approach combining remote sensing techniques and geological field mapping measurements. We utilize satellite imagery, digital elevation models, aeromagnetic data and geological field mapping observations to interpret locations and geometries of active faults along the NW Branch of EARS.

We create neotectonic maps showing intrabasin active faults in the Edward-George Rift Basin, Albertine Rift Basin, and Rhino Graben in the Northwestern branch of the East African Rift System. Generally, the pattern of active faults in the region is dominated by normal faulting consistent with extensional tectonics and major rift-bounding faults oriented roughly parallel to the rift axis, with significant variations in fault length and segmentation. The orientations and segmentation of rift basins in the NW branch of EARS are controlled by pre-existing Proterozoic basement structures based on interpretations from aeromagnetic data. Our neotectonic maps include suture zones that are distinct belts prone to reactivation under changing stress regimes due to strain localization critical for rift initiation along the NW branch of EARS.

This database will be updated regularly with information on the estimation of slip rates of major rift bounding faults that will be obtained using a combination of geodetic velocity measurements, geological strain markers, and Quaternary geochronology. The development of an active fault database for the Northwestern Branch of the East African Rift System is a crucial step in advancing our understanding of regional tectonics and seismic hazards. This comprehensive database will provide valuable information for seismic risk assessment to local governments for better planning regarding infrastructure development. Future efforts to refine and expand the database will further enhance its utility and accuracy, contributing to the broader goal of improving resilience to seismic risks in the region.