Derivation of geomagnetic field to determine geothermal flow at Terak, Bangka Belitung

Abstract

The Geothermal system on Bangka Belitung islands are characterised to a radiogenic type of non-volcanic geothermal energy. The presence of geothermal energy in this region can be attributed to the geological characteristics of granite rocks, which undergo processes such as fracturing, folding, or faulting. The primary objective of this study is to figure out the subsurface heat flow patterns within the geothermal region of Terak. The process of collecting data was conducted via a Proton Precession Magnetometer (PPM) instrument, which consisted of a track of 2.5 kilometres in length. The determination of subsurface heat flow patterns in total magnetic anomaly, regional anomaly, and residual anomaly was achieved through the application of the First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) algorithms. The findings indicate the presence of a subsurface heat flow pattern in the eastern region, which spreads towards the southeast and further extends to the southwest. Notably, this pattern is characterised by abnormal depths ranging from about 20 to 130 metres beneath the surface. The observed phenomenon was in line with the consistent occurrence of geothermal manifestations in the region.