The use of anomaly data in identifying faults in Sedoa village, Poso district

Abstract

Abstract A magnitude (Mw) 6.6 Earthquake occurring on 29 May 2017 in Poso shows that there are active faults in these regions. In addition to Palu-Koro fault which is the major fault in the island of Sulawesi, one of secondary faults that may trigger earthquakes is a fault in Lore Utara Subdistrict, Poso District. This fault has been identified using magnetic anomaly in Sedoa Village Lore Utara Subdistrict. A measurement was done to obtain magnetic field intensity data and measurement time at base stations and position data at mobile stations. The data obtained was subjected to IGRF correction and diurnal variation correction. The result of the research shows different susceptibility (k) values with 0.00017 SI for clay rocks, 0.0209 SI for muddy sandstone, and 0.05 SI for granite rocks. This research also shows the existence of subsurface geological structures in Sedoa Village, Poso District, in the form of two normal faults in different directions. The first fault runs from Southeast toward Northwest and the second one runs from Northeast to Southwest.