IDENTIFICATION OF GRINDULU MINOR FAULT LINES BASED ON MAGNETIC FIELD ANOMALY DATA

Abstract

Abstract
This research aimed to determine the fault direction, pattern of magnetic field anomaly and the subsurface
structure of Grindulu minor fault in Arjosari subdistrcict. Magnetic field anomaly data acquisitons were taken
from 19 points with 500 m grid spacing using Proton Precession Magnetometer (PPM) type G-856AX with looping
method. The results indicate that Grindulu minor fault has a N32˚E direction. Pattern of magnetic field in Grindulu
minor fault was around -360nT to 120 nT. The subsurface structure of Grindulu Minor fault in Arjosari subdistrict
was composed by Arjosari formation and Mandalika formation dominated by rocks lava and breccia tufa with
susceptibility of 1.7 (in the SI) and 1.2 (in the SI) at the depth of (200-400) m.
Keywords: Geomagnetic Method, Grindulu Minor Fault, Suseptibility, Magnetic Field Anomaly