Integrated Geophysical Constraints on Crustal Structure and Along-Strike Heterogeneity beneath Java Island, Southern Sunda Arc
DOI:
https://doi.org/10.17794/Keywords:
Sunda-Java subduction, Seismicity, Focal Mechanism, Gravity Anomaly, Moho Depth (RAPS)Abstract
Southern and central Java are situated along the Sunda–Java subduction system, where interactions among slab geometry, crustal structure, and upper-plate deformation govern regional tectonics and seismicity. Our study presents an integrated geophysical pattern, stress orientations, gravity anomalies, Moho depth variations, and subsurface structures beneath Java. The area spans approximately 106° E-114 °E and 7°S-10°S. We combine earthquake catalog data from 2000-2023 (48,825 events, magnitude range 2.7-7.8 mb, depth range 10-600 km) obtained from USGS data, focal mechanism solutions, event-based stress orientations, satellite-derived gravity data, Radially Averaged Power Spectrum (RAPS) analysis for Moho depth estimation, and two-dimensional seismic reflection profiles. The seismicity distribution depicts a northward-dipping Wadati-Benioff zone and reveals a relative reduction in earthquake occurrence at intermediate depths beneath Central Java. Gravity analysis reveals systematic lateral variations in crustal density and thickness, with high anomalies along the southern margin, low anomalies beneath sedimentary basins, and local high anomalies associated with volcanic regions. RAPS analysis indicates that the Moho depth ranges from approximately 11 to 40 km, consistent with previous regional studies. Seismic reflection profiles document reflector discontinuities and fault-related deformation consistent with frontal, back-arc, and strike-slip fault systems within the Sunda-Java margin.
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Copyright (c) 2026 Rian Amukti, Rashad A Bantan, Hamdy Aboulela, Lina Handayani, Sonny Aribowo
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