Geological Agency: Land Function Change is Not the Main Factor for Cisarua Landslide

Illustration: The joint SAR team evacuates the victims of the landslide disaster found in Pasirlangu Village, Cisarua, West Bandung Regency, West Java, Saturday (24/1/2026) ANTARA FOTO/Abdan Syakura/wsj.

BANDUNG - The Geological Agency of the Ministry of Energy and Mineral Resources (ESDM) stated that land function transfer was not the main factor for the landslide in Cisarua, West Bandung Regency, but rather due to the steep slope morphology and extreme rainfall in recent days.

Earth Explorer, Head of the Geological Agency, Anjar Heriwaseso, explained that the initial study results showed that land movement was influenced by a combination of natural factors, ranging from slope inclination, soil characteristics, to the natural drainage system at the scene.

"The factor of land function transfer does have an effect, but we see the source. The source is in a very steep morphology. We can see that in addition to the steepness of the land, it is also very muddy," he said as quoted by ANTARA, Monday, January 26.

He explained that from the results of the identification, there were very significant morphological differences between the upper and lower slopes with a slope of 30-40 degrees at the top, then decreased to 20-30 degrees at the bottom, thus triggering the mass of soil to move towards the valley.

In addition to morphology, he continued, the soil material factor also plays a major role, because it is formed from very thick volcanic deposits, estimated to be more than 15 meters, with a mushy nature and easy to saturate with water.

"This thick volcanic soil is saturated due to high rainfall, so the strength of the soil is weakened and easily carried to the lower slope," he said.

The Geological Agency also highlighted the role of natural drainage which causes the landslide material to slide with a long distance and makes rainwater accumulate in a narrow drainage path carrying soil and rocks simultaneously, thus creating strong erosion.

"The narrow valley conditions accelerate the flow of material. When it reaches a more gentle area, the material then spreads along the existing river path," he said.

Regarding the type of landslide, the Geological Agency also calls this category of landslide events as a mixture of materials, namely the movement of soil and rock with a dominance of fine-grained material causing landslides to slide further.

On that occasion, he said that extreme rainfall of up to 200 millimeters per day was also another major factor in the landslide.

"The main source of landslides is in a very steep morphology with loose soil. The trigger of extreme rain based on BMKG data reaches more than 200 millimeters per day, so the risk of landslides is very high," he said.

The Geological Agency will also immediately carry out delineation of vulnerable zones to determine safe and dangerous areas, so that the results of the study will be submitted to the local government as a basis for spatial planning and disaster mitigation.

"Areas that have been hit by landslides are not recommended to be inhabited again and need to be relocated. For the surrounding area, it will be determined based on the results of the delineation of the potential for subsequent landslides," said Anjar.