Analysis of Landslide Vulnerability with Hydrothermal Alteration Using Resistivity Methods and Geological Mapping in Songgokerto Village, Batu City

Trunojoyo Street in Songgokerto Village, Batu City, is prone to frequent landslides due to its geomorphology characterized by hills and valleys, ranging from 600 to 3,337 meters above sea level.This road connects major urban and regional centers in East Java, including Batu City, Malang Regency, Kediri City, and Jombang Regency.Landslides obstruct road access, disrupting economic development and endangering road users, especially during peak tourist seasons.The dependence of Batu City's local revenue on agriculture and tourism further exacerbates the economic impact of road closures.This study employs the dipole-dipole resistivity geoelectrical method across 20 survey lines, each measuring 160 meters, with an electrode spacing of 10 meters.Moreover, the resistivity values, initially calculated in Excel, were subsequently processed using Res2Dinv with the Least Squares inversion method to produce two-dimensional pseudo cross-sections.A 2D model was used to visualize the subsurface, facilitating analysis.Results indicate low resistivity values (0-50 .m), interpreted as tuff, and high resistivity values (>50 .m), interpreted as volcanic breccia.Correlation of 2D models with local geological and alteration maps revealed hydrothermal alteration concentrated in zones 1 and 3 at depths of 10-35 meters.The distribution map of hydrothermal alteration is classified into two categories: Prophilitic rocks and Argillic rocks.The Prophilitic rock zone exhibits a dominant resistivity value of 1-100 .m, while the Argillic rock zone has a dominant resistivity value of 100-350 .m.In contrast, unaltered rocks display a dominant resistivity value exceeding 350 .m.These zones correspond to areas with high landslide potential.The alteration of rocks due to continuous heat exposure reduces rock density, increasing porosity and susceptibility to landslides.Furthermore, Uniaxial Compressive Strength (UCS) and Geological Strength Index (GSI) parameter analysis indicate that continuous heat exposure has reduced rock density and increased porosity, thereby elevating the susceptibility to landslides.