• GILBERT P. BAYORAN
The collapse of a sinkhole at Camp Valdez in Brgy. Mambaroto, Sipalay City, Negros Occidental, may have been triggered by the occurrence of multiple large horizontal cracks at the mountain foot slope, according to initial investigations conducted by the Mines and Geosciences Bureau (MGB) of the Department of Environment and Natural Resources.
Benigno Cesar Espejo, MGB-Negros Island director, said they will conduct a ground penetrating radar (GPR) survey to determine the sub-surface ground condition, pinpoint the depth of cracks, and to gain a clearer understanding of the situation.
Initial MGB findings noted 80 to 100 meters of ground vertical displacement with deep cracks, presence of seepages and natural springs, identification of several cave openings, evidence of downward mass movement resulting in canal blockade, signs of recent landslides, and talus deposits.
Espejo raised the possibility that the sinkhole collapse and large horizontal cracks may have been triggered by the recent series of earthquakes and heavy rainfall.
“This type of geological event typically occurs when underlying limestone formations are dissolved by water, leading to a sudden surface depression,” he added.
The affected area has been cordoned off, with public access strictly prohibited by the MGB and Sipalay City Disaster Risk Reduction and Management Office.
Espejo suggested that heavy vehicles be rerouted away from the road near the site, as it may have an impact on the affected mountain slope.
During a meeting on October 20 called by Mayor Gina Montilla-Lizares, which was attended by the MGB representatives and members of the City Disaster Risk Reduction and Management Council (CDRRMC) in Sipalay City, it was agreed that the City Engineering Office should prioritize the widening and clearing of the identified alternative road.
The MGB-Negros Island Region suggested that the Department of Public Works and Highways (DPWH) take a lead in identifying and implementing appropriate mitigating measures in the affected area.*
