On November 21, 2022, the Cianjur area in West Java, Indonesia, experienced devastating landslides caused by a magnitude 5.6 earthquake, with the epicenter traced to a hidden active fault approximately 11 kilometers beneath the surface, known as the Cugenang Fault. This study investigates the post-disaster landslides and aims to discover the characteristics of the landslides triggered by this earthquake. The methodology involves literature review, lithology descriptions, landslide slip surface analysis, soil analysis, slope assessment, land cover and land use change examination, landslide orientation evaluation, and distance measurements to the earthquake's epicenter and the Cugenang fault. Drones aided spatial landslide analysis. The study highlights the strong link between intense shaking along the active fault and landslide occurrences. Due to lithological bedding control, these landslides all head southwest and are located 0.35 to 0.67 kilometres from the fault. The residual soil, highly weathered breccia, and possible tuff volcanic deposits, which act as a sliding plane, lie in a similar direction to the slope, creating a vulnerable setting for landslides. The morphology and exposures of the Sarampad and Rawacina landslides showed similar phenomena to liquefaction. Land use changes, including slope cutting without proper stabilization measures, contribute to landslides to a certain degree.

Landslides are becoming increasingly frequent, intensified by extreme rainfall and human activities, and threaten ecosystems and livelihoods. In Nyomplong, West Java, they have displaced residents and damaged land, which is now repurposed for agroforestry. Sustainable agroforestry management is crucial for reducing landslide risks and enhancing farmer livelihoods, and a comprehensive assessment is required. This study presents Rapid Appraisal for Landslide (Rap-Landslide), a novel method for assessing agroforestry sustainability. Multidimensional Scaling evaluates economic, environmental, social, technological, and institutional dimensions, focusing on key factors in landslide mitigation, land conservation, and productivity enhancement. The approach includes data collection, sustainability evaluation, leverage factor analysis, and validity testing. This study indicates that the sustainability index of agroforestry in Nyomplong ranges from 40.66% to 62.82%, with an average of 56.16%, classifying it as moderately sustainable. Monte Carlo analysis confirms that this study maintains a stable sustainability status with high confidence. Furthermore, Rap-Landslide leverage analysis identifies 15 key attributes significantly influencing sustainability. Key strategies for improvement include more substantial government support in agroforestry policies, farmer group empowerment, the adoption of conservation technologies such as terracing and soil biotechnology, the use of organic fertilizers, appropriate crop selection, and improved market access. Rap-Landslide can be applied to other landslide-prone areas, offering a systematic approach to evaluating sustainability and guiding effective land management strategies.

Earthquake-induced landslides represent a critical threat to transportation infrastructure in tectonically active mountainous regions, particularly in tropical volcanic settings where weak, highly weathered geomaterials dominate. This study develops an integrated framework that directly links physically based seismic threshold modelling with real-time landslide monitoring and operational early warning. The approach is demonstrated in the Cugenang area of Cianjur Regency, West Java, Indonesia, which was severely impacted by the moment magnitude (Mw) 5.6 earthquake in 2022. Slopes composed of highly weathered pyroclastic deposits [Plasticity Index (PI) = 54–68%; porosity > 60%] exhibit low shear strength and high sensitivity to seismic loading. Limit equilibrium analysis using the Morgenstern–Price method that combines the influence of seismic loading and groundwater conditions suggests that a horizontal seismic coefficient (kh) of approximately 0.06, corresponding to a Peak Ground Acceleration (PGA) of about 0.12 gravitational acceleration (g), is a critical threshold for initial landsliding. This comparatively low threshold challenges commonly reported values and demonstrates that slope failure in tropical volcanic terrains can occur under moderate ground shaking, reinforcing the need for site-specific hazard characterisation. The derived thresholds are operationalised within a multi-sensor early warning system integrating Micro-Electro-Mechanical Systems (MEMS) accelerometers and inclinometer measurements. Three hazard levels—Normal (<0.06 g), Alert (0.06–0.12 g), and Emergency (≥0.12 g)are combined with deformation thresholds [30 mm] to capture progressive failure processes and minimise false alarms. By coupling geotechnical modelling and real-time monitoring, this study provides a transferable and scalable framework for enhancing infrastructure resilience in landslide-prone regions.

Landslides pose a significant natural hazard requiring cost-effective, sustainable mitigation strategies. Nature-based solutions utilizing vetiver (Chrysopogon zizanioides) demonstrate considerable potential due to its deep, dense root system, which enhances soil reinforcement. This study examines the effects of growth medium composition and NPK fertilization on the root mechanical properties, biomass accumulation, and vegetative growth of vetiver under controlled greenhouse conditions. The planting medium comprised landslide-affected soil mixed with compost in varying proportions, combined with different NPK fertilizer levels. Root tensile strength was measured to assess mechanical performance, while biomass and vegetative parameters were evaluated to determine growth responses. Results indicate that both growth medium composition and fertilization significantly influence biomass production, root diameter, and tensile strength. The highest biomass (178.33 g) was recorded under T80P20N7.5, while the greatest root diameter (1.47 mm) and tensile strength (21.9 MPa) were observed under T100P0N0. These outcomes suggest a trade-off between biomass production and mechanical reinforcement. Overall, optimizing soil amendments and nutrient inputs enhances vetiver’s bio-reinforcement capacity, supporting its application in sustainable slope stabilization and landslide mitigation.

Background: This study is a forensic back-analysis of the 2021 embankment failure at KM 178 of the Cisumdawu Highway, Indonesia. The post-failure investigation identified weak subsurface materials but no discrete failure horizon, and the mechanism was never established. Six independent lines of field evidence were assembled, from UAV LiDAR geomorphology to paired triaxial and direct shear testing. A two-dimensional Morgenstern–Price model was built with the failure surface fixed from that evidence while material parameters were calibrated. Pore pressure was represented as a material-specific ratio rather than a piezometric surface, the residual soil permeability being too low to transmit storm rainfall to depth. Uncertainty was propagated by Monte Carlo simulation. Results: The alignment crosses a valley floored by relict landslide deposits, with arcuate paleo-scarps on the upper slope. The weathering profile grades from residual silty clay through residual silty sand to weathered tuff, placing a granular horizon within low-permeability clay, so permeability is not monotonic with depth. Inclinometers installed after the rupture intercepted a shear horizon at 559 and 536 m elevation, recording 15 cm and 10 cm of cumulative wet-season displacement, while the instrument monitored during the dry season recorded none. Deeper horizons remain active but could not be traced laterally, indicating a larger relict complex. That horizon coincides with N-SPT below 10 enclosed within material returning 20 to 30, a strength inversion weathering cannot produce, and with gravelly deposits of low resistivity. Without imposed pore pressure it is not the critical surface, returning 1.40 against 1.29 for a shallower surface within the embankment. It becomes critical only when the pore-pressure ratio reaches about 0.37, at an operational friction angle of 20.5°, below the measured peak of 29°. Sensitivity analysis identifies that ratio, not embankment strength, as the dominant control. Conclusions: The failure is best explained as rainfall-driven reactivation of a relict shear surface, recharge reaching it laterally through the granular horizon rather than by vertical infiltration. The relict surface was the necessary condition and the pore-pressure rise the sufficient one. On relict landslide terrain, mitigation should target drainage of the basal horizon rather than strengthening of the embankment.