GIS-Based Landslide Risk Screening in Segamat, Johor, with Historical Earthquake Context

Abstract

Landslide assessment in humid tropical, low-seismicity regions requires a clear distinction between terrain susceptibility and the consequences associated with exposed populations and infrastructure. This study develops a geographic information system (GIS)-based screening framework for Segamat, Johor, by integrating physical susceptibility, exposure, and vulnerability through multi-criteria decision analysis and the Analytic Hierarchy Process (AHP). Nine physical indicators, ten exposure indicators, and six vulnerability indicators were standardised into five ordinal classes and combined using weighted overlay. The three component surfaces were then multiplied to produce a relative landslide-risk index. High and very high physical susceptibility were concentrated in eastern and south-eastern Segamat, where steeper slopes, greater rainfall, dense lineaments, and proximity to rivers coincide. Exposure was more localised around settlement and service centres, while vulnerability increased in areas with larger concentrations of dependent population groups and poorer access to emergency and health facilities. The integrated map identified priority clusters around Kampung Abdullah and Taman Tan Leng Ann, together with isolated patches in eastern Segamat that warrant field verification. A supplementary co-location analysis found that moderate-to-very-high susceptibility occupied 53.3%, 46.0%, and 51.7% of nested 5, 15, and 25 km earthquake buffers, respectively. Because the susceptibility model contains no ground-motion variable and the buffers are nested, these percentages do not establish earthquake triggering or attenuation. The output is therefore best interpreted as a regional screening tool for directing landslide inventories, geotechnical investigations, development review, and preparedness, rather than as a probabilistic hazard forecast or parcel-level stability assessment.