Journal of Volcanology and Geothermal Research https://doi.org/10.1016/j.jvolgeores.2025.108472
The western Java region is situated along the Sunda Arc, which is formed by subduction of the Indo-Australian Plate beneath the Eurasian Plate. The subduction process causes seismic activity in the Wadati-Benioff zone of the descending slab, produces a chain of active volcanoes, and forms numerous faults in the terrestrial and back-arc region of the overriding plate. This study examines the region’s tectonic system via seismic tomography, in which the most recent earthquake catalog from the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) is utilized. Body wave travel time from 4561 local-regional earthquakes recorded by 78 seismic stations produces a 3-D Vp and Vp/Vs ratio model. The subducting Indo-Australian Plate slab is characterized mainly by high Vp and low Vp/Vs anomalies and exhibits steeper subduction than the Slab2 model. Partial melting zones, which serve as magma sources for several volcanoes, are observed at depths of about 90–100 km, characterized by low Vp and high Vp/Vs anomalies. The Lembang and Cimandiri fault lineaments are visible at 10 km depth and are characterized by negative Vp and positive Vp/Vs anomalies. This study also successfully demonstrates that the source of the damaging 2022 Cianjur earthquake occurred in a region dominated by low Vp and high Vp/Vs. These anomalies most likely relate to fluids or molten material in the fault zone. This study again highlights the importance of the BMKG seismic network for understanding tectonic systems on a local-regional scale, in this case, through the lens of seismic tomography.
Authors: W. Wandono, M. Ramdhan, A.N. Aulia, A.B.Pangestu, E. Hidayat, S. Syuhada, S. Widiyantoro, Nicholas Rawlinson, T.Anggono, B. Pranata, M.M. Mukti, M.P. Maulana
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