Travel Time Tomography to Delineate 3-D Regional Seismic Velocity Structure in the Banyumas Basin, Central Java, Indonesia, Using Dense Borehole Seismographic Stations

The Banyumas Basin is a tertiary sedimentary basin located in southern Central Java, Indonesia. Due to the presence of volcanic deposits, 2-D seismic reflection methods cannot provide good estimation sediment thickness and subsurface geology structure this area. In study, passive tomography (PST) method was applied image 3-D Vp, Vs, Vp/Vs ratio. We used 70 seismograph borehole stations with recording duration 177 days. A total 354 events 9, 370 P 368 S phases were as input for tomographic inversion. checkshot data 4, 400-meter deep exploration well (Jati-1) within network constrain shallow crustal layer initial 1-D velocity model. model resolution inversions assessed using checkerboard test (CRT), diagonal element (DRE), derivative weight sum (DWS). Using obtained ratio, we able sharpen details geological structures from previous studies, fault could be well-imaged at depth 4 km. interpreted main dextral strike-slip that controls pull apart process Basin. layers, its layering, also determined. found prominent features contrast aligned very boundary between Halang Rambatan formations observed Jati-1 data. Furthermore, an anticline structure, which potential structural trap petroleum system Basin, imaged. This made possible due dense seismographic deployed study