The DENR, Mines and Geosciences Bureau in Region 6 (MGB-6) observed large landslides in the slopes of the mountains at the headwaters of the Maninila River in Barangay Panpanan 2 in the town of San Remigio, Antique during an investigation on October 10-12, 2009
The team recommended that houses, families, schools and other structures affected by the landslides and active soil creep must be relocated to safer locations, preferably in flat to gently sloping areas and far from bodies of water.
The municipality of San Remigio requested MGB-6 to investigate after they have observed artificial damming at the headwaters of the Maninila River.
Dr. Leilanie Suerte, geologist of MGB-6 said that the landslide occurred at the headwaters of the Maninila River, four kilometers away (aerial distance) from the West Panay Fault. The landslide site is also at least four kilometers away (aerial distance) from Brgy. Panpanan.
The landslides with semi-circular shapes were at least 70 meters long, more or less 50 meters wide and about 2 meters deep.
According to her, the main causes of the landslide is the steep slopes of the mountains, severely weathered and highly jointed rocks underlying these mountains, abundant groundwater and heavy rains that fell in the area for several weeks.
She said that the occurrences of heavy rain in the area and the already abundant groundwater seeped through numerous cracks of the severely weathered rocks. A mass of broken rocks and soil oversaturated with water at steep slopes will naturally move downward causing slope failure and mass movement or landslide.
Residents of Barangay Panpanan 2 reported that the landslide debris formed an artificial dam. Water was impounded in this artificial dam and the residents feared that a large volume of impounded water will cause flashfloods downstream if the artificial dam is breached.
However, based on the ocular inspection of MGB-6 at the landslide site, the topography of the area and the channel capacity prevented the artificial dam from storing a large volume of water that could cause widespread flooding downstream. MGB-6 still cautions communities living along the Maninila River to be vigilant especially during the rainy season.
The MGB-6 team also assessed the barangay proper and some sitios of Brgy. Sumaray, Brgy. Walker, Brgy. Panpanan 1 and 2 and Brgy. Insubuan.
The church, elementary school, several houses and farmlands were affected by soil creep, landslides, river bank scouring, flooding and erosion in barangay proper of Panpanan 2, barangay proper of Brgy. Insubuan and Sitio Libudon, Brgy. Insubuan.
The team explained the current situation and future scenarios in the landslide areas in the headwaters of the Maninila River. They also disseminated information to the affected residents and municipal officials in the barangay proper of Brgy. Panpanan 1 during an information and education campaign (IEC) last October 11, 2009.
In its report given to the municipal mayor of San Remigio, MGB-6 recommended relocation of affected houses and structures and that the municipality should conduct continuous disaster preparedness trainings for barangay officials and residents in barangays with moderate to high landslide susceptibility rating and those prone to flooding in the geohazard assessment.
