Active fault mapping in the onshore northern Banda Arc, Indonesia: Implications for active tectonics and seismic potential

The northern Banda Arc accommodates some portion of the left-lateral slip due to the Pacific plate’s rapid westward movement relative to the Australian plate. The region is seismically active and has experienced several damaging earthquakes. However, the active tectonics of the northern Banda Arc is poorly understood. We mapped and described the tectonic geomorphic features in the northern Banda Arc using 3D anaglyph images, constructed from the Indonesian Digital Elevation Model (DEMNAS) ~8 m resolution. We combined our interpretation with seismicity data, published structural maps, and geodetic measurements to discuss the active tectonics of the northern Banda Arc and its seismic hazard. In north Seram, geomorphic features such as uplifted marine terraces, fault scarps, and wind gaps on a ridge represent active thrust-faulting activity. The Kawa and Bobot faults are the major left-lateral strike-slip faults in central and east Seram and are characterized by linear valleys, offset rivers, beheaded rivers, pressure ridges, and shutter ridges. Numerous active faults cut uplifted marine terraces in Amahai, Ambon, and surrounding islands. Some active faults bound intramountain depressions in central Buru. Our analysis suggests that active faults in the study area likely to accommodate the convergence of the northern Banda Arc and the Bird’s Head of Papua in an east-northeast direction. We suggest that active faults in the region can produce ≥ Mw 6.4 earthquakes. The 34-km-long Ambon fault may cause a devastating earthquake as it traverses Ambon City, the capital of Maluku Province.