BANDUNG - The Geological Agency revealed that the tragedy of the land movement that buried 30 hectares of land in Pasirlangu Village, Cisarua, West Bandung, was not just a normal hydrometeorological disaster, but there was a combination of ancient geology and groundwater saturation.
Acting Head of the Geological Agency Lana Saria explained that based on in-depth analysis, there was a fatal combination between the fragile ancient geological structure and groundwater saturation that triggered the slope failure in the quite densely populated area.
"The characteristics of the soil at the scene, a geological time bomb that finally exploded," Lana said, quoted by ANTARA, Monday, January 26.
Based on the analysis of secondary data and the latest deskwork, Lana explained that the location of the disaster, which is at the coordinates of LS 6.796861° and BT 107.539694°, stands on the rock unit of the Old Volcanic Sedimentary Formation (QVu).
"This unit generally consists of volcanic breccias, tuffs, andesite-basalt lava, and pyroclastic material that has undergone strong weathering," he said.
Further weathering of these volcanic rocks, drastically reduces the shear strength of the soil. The situation is exacerbated by the presence of geological structures in the form of faults and northwest-southeast-oriented cracks.
These microscopic cracks become a toll road for rainwater to infiltrate deep into the ground, creating weak fields that are ready to slide millions of tons of soil material at any time.
The main triggering factor is inevitable high rainfall. The intensive infiltration of rainwater into the weathering soil layer causes a significant increase in pore water pressure.
When this water pressure increases, the soil cohesive force (cohesion) weakened. When the slope driving force exceeds the restraining force, the movement of soil and rock mass occurs following the slip plane that develops in the weak zone.
This explains the technical mechanism of why the landslide covers such a large area.
In addition to natural factors, human activities also accelerate this process. Land use which is dominated by settlements and agriculture, coupled with slope cutting for roads without adequate drainage systems, has disturbed the stability of natural slopes whose slopes reach more than 40 degrees in some points.
Considering that the location of the incident is within the Medium Land Movement Vulnerability Zone in the ZKGT Map, the technical team issued crucial recommendations that must be followed to prevent an increase in casualties.
The technical recommendation confirms that people around the affected area should immediately evacuate to a safer place. The potential for subsequent landslides is still very high, especially because the soil structure has been disturbed.
"Handling landslides and searching for missing victims should pay attention to the weather, so that it is not carried out during and after heavy rain," said Lana.
This warning is crucial because subsequent ground movements can affect SAR officers and volunteers working in the danger zone.
In addition, the installation of disaster-prone signs and mitigation socialization is now an urgent priority. The public is asked not only to be aware of the rain, but also to understand the early symptoms of soil movement in their living environment.
The West Java Regional Disaster Management Agency (BPBD) revealed that until now, due to the landslide on Saturday (24/1) morning, 19 people were reported dead, 73 people were still missing, 666 people were displaced, and 51 houses were severely damaged.
The English, Chinese, Japanese, Arabic, and French versions are automatically generated by the AI. So there may still be inaccuracies in translating, please always see Indonesian as our main language. (system supported by DigitalSiber.id)
