M. Yusuf¹

¹Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG)

Abstract:

As part of the Indonesian PRIMA 2017 sea trial, a geophysical survey was conducted from the research vessel Baruna Jaya VIII along a track named leg #1 from Jakarta to Sabang via Indian Ocean, and along a track named leg #2 from Sabang to Jakarta via Malacca Strait. The objective of this research is to observe the tectonic structure of Malacca Strait in the North of Pidie. The methods used in this research include observations of the seabed topographic with single-beam echo sounder, the seabed geological condition with a sub-bottom profiling (SBP) tool, and modelling of gravity anomalies from topex satellite data. In the gravity modelling, the second vertical derivative (SVD) analysis was used to determine the type of fault, and the grav3D inversion modelling was implemented to estimate the density distribution. From this research, the survey area has at least four different slopes, i.e., a relatively flat region with almost no slope, somewhat steep, sloping, and slightly sloping. For the geological condition, the seabed is composed of hard rock and sediments that reach 30 meters in thickness, typically for the normal fault. The SVD modelling confirms the existence of this normal fault. The grav3D inversion modelling shows a basin structure with soft rock on the top layer and hard rock in the lower layers with an oblique structure.