Big Rock Falls In Lembang Due To Prosperous Geological Conditions

JAKARTA - The Geological Agency, Ministry of Energy and Mineral Resources (ESDM) revealed that the fall of three large stones on Mount Batu, Lembang, West Bandung, Saturday, November 8, was a natural phenomenon due to unstable geological conditions in the local location.

"This is a natural phenomenon due to unstable geological conditions. It may be triggered by small vibrations or internal rock factors," said Head of the Geological Agency M Wafid, ANTARA, Sunday, November 9.

Based on a report received by the Geological Agency, the large rock fall from the cliffs of Mount Batu, Lembang took place without heavy rain or significant earthquakes recorded around the location.

According to preliminary observations from the team that was deployed, said Wafid, the location of the rock fell was on a steep slope with a slope of more than 60 degrees, which was composed by volcanic rock that had suffered cracks and weathering.

"There is also a fracture area that extends parallel to the slope, and shows the potential for releasing rock blocks. This condition indicates that the rock is in a state close to the stability limit (equilibrium limit)," said Wafid.

Based on the analysis of the mechanism, continued Wafid, this phenomenon is included in the category of falling-type rock mass movement (rockfall) with the main trigger of possible internal weaknesses of rock due to cracks and natural weathering, microwave vibrations that are not recorded in the main but sufficient system to trigger the release of fragile rock blocks, as well as changes in temperature and recurrence which may also contribute to further cracks.

"The cliff area has the potential to be exposed to further stone falls, especially during the transitional season or during mild vibrations. Then the roads and buildings of residents under the cliffs are at high risk of similar hazards," he said.

Therefore, the Geological Agency recommends installing a safety wire net (rock mesh) and a rock barrier at the foot of the cliff. Then restrictions on activities and construction in areas prone to falling stones.

Then micro-seismic monitoring is carried out by technical agencies to determine the potential for trigger vibrations in Lembang fault areas as well as public education regarding early signs of new cracks and slopes.

"The public is advised to remain alert to the potential for similar incidents, especially around steep cliffs that are composed by weathered and maturized volcanic rocks," said Wafid.

Residents of Sukamulya Village, RT 01/10, Langensari Village, Lembang District, West Bandung Regency (KBB), West Java, were shocked by a number of large stones that suddenly fell from the top of Mount Batu on Saturday (8/11).

"Based on information, there was a landslide of three stones from Mount Batu. It happened at 12.10 WIB," said the KBB Regional Disaster Management Agency (BPBD) Asep Sehabudin when confirmed.

Three large stones suddenly fell from the cliff without rain, without earthquakes, without strong winds. Asep made sure there were no casualties in the incident. It's just that a green house was damaged after being hit by a large rock that rolled from the top of Mount Batu.

"One of the biggest stones even hit the walls of the residents' green house cacti, tearing the walls of the green house," said Asep.