Sediment and Crustal Structure Beneath East Kalimantan and East Java, Indonesia From Receiver Function

Abstract

We investigate the sediment and Earth’s crustal structure beneath the East Kalimantan and East Java by modelling the stacked receiver function from six seismic broadband stations belong to the Meteorology, Climatology and Geophysics Agency of Indonesia (BMKG). The calculation of receiver functions from 60 teleseismic earthquake events using iterative time-domain deconvolution method. Inversion result shows a significant variation in the sediment layer thickness from 1 km to 4 km beneath East Java. It is correlated with the South East Java basinal area (station KRK) and the North East Java Basin (station GRJI and BWJI). The sediment layer of about 5 to 10 km beneath East Kalimantan is associated with the Kutai Basin (station SGKI, SMKI, and BKB). Average Sediment layer shear velocity (Vs) beneath all station is observed to be less than 2.31 km/s. Crustal thickness beneath East Java varies between 20 to 40 km and 34 to 50 km beneath East Kalimantan, with average crustal shear wave velocity, Vs 4.60 km/s.

Sediment Thickness and Moho Depth Beneath Western Indonesian Region From Teleseismic Receiver Function

“…Other researchers performed the receiver function study in the island of Java where the thickness of the crust in the western part of the island was 25-37 km (Syuhada and Anggono, 2016; Anggono et al, 2020), in the central and east part of Java island about 25-39 km (Wölbern and Rümpker, 2016;Amukti et al, 2019). Recently, the receiver function study using limited number of stations in Borneo or Kalimantan Island was carried out by Bahri et al, 2021. They showed the evidence of thickening of the Earth's crust in cross-section from east Java to the north to Borneo Island.…”

Sediment thickness in the eastern part of Kalimantan from high-frequency receiver functions

“…They found that the sedimentary layer beneath a seismic station near the Tarakan Basin has a thickness of at least 2 km. However, the sedimentary thickness of around 0.55 km obtained for station SGKI is considerably less than that reported by previous seismological global and local studies [e.g., 13,14,21]. All these previous 1227 (2023) 012044 IOP Publishing doi:10.1088/1755-1315/1227/1/012044 4 studies suggest that the sedimentary layer with a thickness of more than 3 km covers the study area.…”

A preliminary results: study of crustal thickness in eastern part of Borneo, Indonesia from teleseismic receiver function analysis

“…Research in East Java indicated sediment layer thickness of about 1-4 km with an average Vs velocity of approximately 2.40 km/s, and crustal layer with an average Vs velocity of 4.70 km/s at a depth of 20 -40 km. In East Borneo, the results revealed sediment thickness ranging from 5-10 km with an average Vs velocity of about 2.22 km/s, and the thickness of the Earth's crust varied between 34-50 km with an average Vs velocity of 4.48 km/s [11]. Furthermore, research in Borneo Island, divided into 5 zones -Sabah Zone, East Borneo Zone, Maratus Zone, Northwest Zone, and Southwest Zone, was conducted using nonlinear inversion methods.…”