Magnetic characterization of soils in landslide area (Case study: Cihanjuang Village, Sumedang, West Java)

Abstract A landslide is one type of natural disaster due to the movement of masses of soil or rock moving down the slope. There is a place in Cihanjuang Village, Sumedang Regency that has experienced a landslide disaster. A landslide is a form of natural disaster resulting from the descent of large quantities of soil or rock down a slope. Cihanjuang Village in Sumedang Regency is one area that has been affected by such a landslide. The rock magnetism is one of the methods that can be used to analyze the characteristics of soil in potential landslide areas. Regarding the landslide and its soil properties, this research aims to distinguish the soil characteristics between non-landslide and landslide-prone areas in Cihanjuang Village, Sumedang Regency. The soil characteristics will be analyzed using magnetic susceptibility by low-frequency magnetic susceptibility (χLF) and frequency-dependent magnetic susceptibility (χFD%) values along with the morphology and mineralogy of magnetic grains by scanning electron microscopeenergy dispersive x-ray (SEM-EDX) and x-ray diffractometer (XRD). The χLF values of soil samples from non-landslide areas (outcrop) ranged from 327,21 – 409,34 × 10−8 m3/kg, whereas in the landslide-prone ranged from 202,87 – 408,56 × 10−8 m3/kg. The cFD% value in non-landslide and landslide areas ranged between 3,32 – 7,53% and 1,46 – 6,30%, respectively. The soil from non-landslide areas tends to have higher magnetic susceptibility values than landslide areas. Both soil samples have an abundance of superparamagnetic (SP) [ine grain. However, the morphology of non-landslide and landslide areas can be distinguished by grain size. This differentiation is based on the size of magnetite minerals present in the soil samples, as identi[ied by XRD analysis. Based on SEM-EDX analysis, the lower magnetic susceptibility values in landslide areas were identi[ied due to the low abundance of superparamagnetic or the high abundance of multi-domain (MD) particles that have a bigger size of magnetic grains than non-landslide areas.