Thesis (B.S.) -- Cagayan State University, 2025.

Landslides are among the most frequent and destructive geological hazards worldwide, often triggered by natural factors such as intense rainfall, earthquakes, and slope instability. The Philippines, situated along the Pacific Ring of Fire and exposed to frequent typhoons, is particularly vulnerable to rainfall-induced landslides, especially in mountainous regions like Northern Luzon. In response to recurring slope failures in Purok Danna, Barangay Manga, Peñablanca, Cagayan, this research investigates the landslide vulnerability and slope stability of the study area with the objective of identifying appropriate mitigation measures based on geotechnical and hazard assessments. Geotechnical investigation report data were collected to determine the key parameters such as unit weight, cohesion, and internal friction angle as well as the slope profile of the study area. Geotechnical parameters were analyzed using Rocscience software with Bishop and Janbu methods to assess slope stability under both static and seismic conditions, enabling a comprehensive performance comparison. Landslide vulnerability assessment using HazardHunterPH revealed that the study area has high susceptibility to rain-induced landslide however it is considered safe from earthquake-induced landslides despite being prone to Intensity VIII ground shaking. The slope stability analysis using Rocscience revealed that the factor of safety in all scenarios remained below 1.0, indicating very low slope stability. While structural interventions such as retaining walls and slope anchoring were considered, spatial and technical constraints rendered them impractical. Consequently, a bioengineering solution involving the application of MacMat R1 erosion control mats combined with hydroseeding was proposed. This method demonstrated a 96.8% reduction in soil loss and provided sufficient tensile strength and anchorage to counteract active forces. The study concludes that environmentally sustainable surface protection systems are effective and feasible alternatives for landslide mitigation in geologically sensitive areas.

Keywords: Landslide vulnerability, Slope stability analysis, Bioengineering solutions