Madlazim Kasmolan, Bagus Santosa, Jonathan Lees, Widya Utama
Fifteen earthquakes (Mw 4.1-6.4) occurring at ten major segments of the Sumatran Fault Zone (SFZ) were analyzed to identify their respective fault planes. The events were relocated in order to assess hypocenter uncertainty. Earthquake source parameters were determined from three-component local waveforms recorded by IRIS-DMC and GEOFON broadband IA networks. Epicentral distances of all stations were less than 10°. Moment tensor solutions of the events were calculated, along with simultaneous determination of centroid position. Joint analysis of hypocenter position, centroid position, and nodal planes produced clear outlines of the Sumatran fault planes. The preferable seismotectonic interpretation is that the events activated the SFZ at a depth of approximately 14-210 km, corresponding to the interplate Sumatran fault boundary. The identification of this seismic fault zone is significant to the investigation of seismic hazards in the region.
Physics Department, Faculty Mathematics and Science of ITS, Surabaya 60111, Jl. Arif Rahman Hakim I, Indonesia; Physics Department, Faculty Mathematics and Science, State University of Surabaya (UNESA), Surabaya 60231, Jl. Ketintang, Indonesia; Department of Geological Sciences, University of North Caroline at Chapel Hill Seismology, Volcanology, United States
