Shear wave structure beneath a station in West Java, Indonesia from joint inversion of receiver function and surface wave dispersion

• Main Authors: Anggono, Titi, Syuhada, Febriani, Febty, Prasetio, Aditya D., Dewi, Cinantya N., Hasib, Mohammad, Sulaeman, Albert
• Format: Conference Proceeding
• Language: English
• Subjects: Earthquakes; Heat transmission; Plates (tectonics); S waves; Shear; Subduction (geology); Surface waves; Velocity; Wave dispersion
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0106245

West Java, Indonesia is part of Java Island, which is the most populous Island in Indonesia. The region is characterized with earthquakes from subducting plate of Indo-Australian beneath Eurasian plate. The region is also characterized by the presence of Cimandiri fault zone encompassing cities along its trend. In this preliminary study, we estimated crust and upper mantle structure beneath CISI station of GE network. Joint inversion of observed receiver function from teleseismic events and surface wave dispersion from a regional earthquake was carried out. Surface wave dispersion used in this study because it is more sensitive to the shear velocity model, while receiver function is more sensitive to the medium discontinuity. A total number of receiver functions used in the inversion is about 74 receiver functions. Inversion results suggest that sediment thickness varies about 1-2 km thick. Moho depth is estimated to be about 36 km depth. A notable intra crustal low velocity zone is observed from the shear velocity zone at depth of 24-28 km depth. Shear velocity reduction is ∼16% compared to the upper and lower layer. By assuming the mechanism to be partial melt, relationship model suggests that 6-7% melt is present beneath the station. Further studies such as heat flow analysis, rock parameters are necessary to constrain the possible mechanism for the seismic velocity decrease.