SUPERVISOR: Christian ZANGERL

PROJECT ASSIGNED TO: Misbahudin MISBAHUDIN

The volcanic area in Indonesia is geologically characterized by the presence of pyroclastic products, which are prone to intense weathering and thus susceptible to different types of landslides. Combined with adverse weather conditions related to the tropic climate, landslide activity is generally high in volcanic soils, leading in the past to numerous events in the Cipongkor District, West Bandung, in Indonesia. On March 28th, 2024, a landslide affected a densely populated settlement area, destroying some houses and impacting the provincial road crossing the landslide area.

This research investigates the geological, geomechanical and hydrogeological characteristics of the slides and proves the influence of precipitation on the initial formation process. The applied methods are manifold and comprise UAV-based aerial mapping supported by geomorphological-geological field observations, geotechnical drilling including core sampling, geomechanical properties examination, analyses of meteorological data, and numerical modeling. The geometry and volume of the landslide were determined by UAV and field mapping by reconstructing the pre-failure topography. The lithostratigraphic data obtained from the borehole are improved by resistivity (ERT) measurements, in order to build a geological subsurface model of the slide. Based on this and considering hydrogeological and geomechanical data numerical modeling is applied to simulate the initiation of the slide by applying a transient approach which is able to study precipitation data, pore pressure changes and slope failure.

Preliminary results show that the stratification of ash tuff and lapilli layers, with their variation of weathering may provide a disposition factor for the formation of the slide. Data from the nearest local meteorological station show that cumulative precipitation in the research area during the rainy season (October 2023 to March 2024) was 1230 mm. Furthermore, in the 3 consecutive days before the slide event precipitation reached 95 mm, suggesting that heavy precipitation may have acted as a trigger that caused the failure event of this first-time slide.