STRESS REGIME ANALYSIS IN THE STRUCTURAL TRANSTITION BETWEEN SUMATRA AND JAWA

Hikhmadhan Gultaf (Department of Geological Engineering, Institut Teknologi Bandung (ITB) Ganesa Street No.10, Bandung, Indonesia)
Benyamin Sapiie (Department of Geological Engineering, Institut Teknologi Bandung (ITB) Ganesa Street No.10, Bandung, Indonesia)
Wahyu Triyoso (Department of Geophysical Engineering, Institut Teknologi Bandung (ITB) Ganesa Street No.10, Bandung, Indonesia)
Meli Hadiana (Department of Geological Engineering, Institut Teknologi Bandung (ITB) Ganesa Street No.10, Bandung, Indonesia)
Yehezkiel Halauwet (Agency for Meteorology Climatology and Geophysics (BMKG) Ambon, 97122, Indonesia)
Herlina Almanda Anna Maria Narwadan (Agency for Meteorology Climatology and Geophysics (BMKG) Ambon, 97122, Indonesia)

Scientific Contributions Oil and Gas
Vol 48 No 1 (2025)

The structural transition between Sumatra and Java presents significant geological challenges due to the change in the orientation of the convergent plate boundary, shifting from NW-SE in western Sumatra to W-E in southern Java. This study focuses on the regions of Lampung (representing Sumatra's tectonics), West Java (representing Java's tectonics), and the Sunda Strait as the boundary between them. The research aims to map tectonic stress conditions using formal stress inversion methods based on earthquake focal mechanism data, constrained to depth intervals of 0-15 km and 15-33 km. Focal mechanism data are categorized by geographic and regional structural geology with kinematic homogeneity, leading to the identification of ten inversion zones. Findings show that Lampung's average stress regime ( ) is strike-slip fault regime at both depth intervals. The Sunda Strait displays a transtensive fault regime across these depths, while West Java has a thrust fault regime at 0-15 km, transitioning to strike-slip fault regime at 15-33 km.