Identification of subsurface structure based on geomagnetic method in Tangkuban Parahu Volcano, Bandung, Indonesia

Tangkuban Parahu Volcano is one of the active volcanoes located in West Bandung Regency, West Java. According to Geological Map of Tangkuban Parahu there is a fault structure with a northwest-southeast direction that accros through Ratu Crater and its status is still estimated. The presence of this structure is expected to worsen the condition of the volcanic eruption that occurred because of its location across the Ratu crater which became the center of the eruption in recent times. Therefore, it is necessary to study the condition of the subsurface geological structure of Tangkuban Parahu Volcano as an early mitigation effort and reduce the risk due to volcanic activity that occurs. The study of the subsurface conditions of Tangkuban Parahu Volcano was carried out using a geomagnetic method that utilizes the magnetic properties of rocks to study the conditions below the surface. Based on the research that has been done, it is found that the magnetic anomaly distribution value from the Reduce to Pole is in the range of -193,008 to -924,656 nT where the magnetic anomaly distribution in the Ratu Crater and Upas Crater areas has a relatively lower magnetic value compared to the surrounding area. This is due to the demagnetization process which weakens the magnetic value in the crater area. Further analysis was carried out on geomagnetic data using derivative analysis in the form of First Horizontal Derivative and Second Vertical Derivative which resulted in indications of fault structures trending north-south and west-east. From the results of the Euler deconvolution, it shows the presence of faults ranging from 200 to 350 m depth.