Identification of Geophysical Conditions of Landslide Areas Ngargoyoso District, Karanganyar Regency

Abstract

Landslides continue to pose a major threat to communities living in mountainous areas, such as Ngargoyoso District. Previous studies have shown that landslide points are scattered across several villages: Dukuh Village with 9 points, Nglegok with 2 points, Jatirejo with 1 point, Ngargoyoso with 6 points, Kemuning with 5 points, Segorogunung with 10 points, Girimulyo with 3 points, and Berjo with 5 points. The pattern of landslide events in the study area is clustered, with an average value of 0.65. This research aims to identify and analyze the geophysical characteristics of landslides in Ngargoyoso District. The initial step in the research involved a literature review on factors causing landslides, followed by creating a list of areas as location guides. Landslide identification was carried out descriptively, and various factors believed to contribute to landslides were identified and analyzed. The results of this study indicate that (a) geophysically, landslides in the area mostly occur in regions characterized by high rainfall (394.1 mm/hour), moderate to steep topography (slope ≥9%), geological formations consisting of Lawu volcanic rock, geomorphological features of faulted folding hills, and land use primarily involving buildings and settlements; and (b) the main type of landslide is predominantly the fall type, consisting of soil, gravel, and rock materials, totaling 24 points, along with creep-type landslides observed at 17 points. Fall-type landslides are dominantly found in Nglegok Village (2 points), Dukuh Village (5 points), Ngargoyoso Village (4 points), Kemuning Village (5 points), Puntukrejo Village (1 point), Girimulyo Village (1 point), Berjo Village (3 points), and Segorogunung Village (1 point). Meanwhile, creep-type landslides are spread across Segorogunung Village (8 points), Berjo Village (2 points), Girimulyo Village (2 points), Ngargoyoso Village (2 points), Dukuh Village (2 points), and Jatirejo Village (1 point).