Abstract
Landslides are a recurrent problem in hilly regions, particularly during the rainy season, causing fatalities, infrastructure damage, and socio-economic disruption. Landslide hazard mapping is therefore essential for identifying vulnerable areas and developing effective mitigation strategies. This study aimed to create a landslide hazard map for the Medan–Berastagi road using the Analytic Hierarchy Process (AHP) integrated with Geographic Information Systems (GIS). Eleven parameters were selected, including slope angle, slope height, slope aspect, rainfall, drainage, lithology, soil type, land use, distance to faults, seismic activity, and proximity to rivers. Data were compiled through field surveys, GPS verification, and secondary sources, then processed with QGIS. Hazard levels were classified into five categories: very low, low, moderate, high, and very high. Results show that 44% of the road segments (19 km) fall under moderate hazard, 46% (29 km) under high hazard, and 9% (3 km) under very high hazard. Field validation using 71 landslide inventory points yielded an accuracy of 97.6%. The most influential factors were slope angle, slope height, rainfall intensity, and land use. Prolonged heavy rainfall on steep slopes underlain by fractured volcanic rocks contributed significantly to slope instability. The developed hazard map demonstrates that most of the Medan–Berastagi corridor is vulnerable to landslides, emphasizing the need for targeted disaster risk mitigation. These findings provide a scientific basis for regional planning and sustainable infrastructure management in mountainous terrains.