By Francis Allan L. Angelo

RESIDENTS of five villages in San Remigio, Antique must be relocated least they will be buried alive in a landslide.

The Department of Environment and Natural Resources (DENR) issued the recommendation following the occurrences of cracks and landslides in the said area.

In a report, the DENR’s Mines and Geosciences Bureau (MGB) said Brgys. Panpanan I, Panpanan II, Sumaray, Walker, and Insubuan are considered landslide prone areas.

The MGB evaluated the villages upon request of San Remigio Mayor Elizabeth C. Coloso.

Residents in the said barangays observed mass movements (cracks and landslides) and artificial damming at the headwaters of Maninila River after a landslide.

Landslides had occurred in the area in September to early October at the headwaters of Maninila River. The landslide was 70 meters long with about 7,000 cubic meters of debris deposited at the narrow river channel below, creating an artificial dam.  

“The rain water was accumulated by the artificial dam upstream and when the artificial dam broke up the accumulated debris flowed downstream and although it did not cause flooding, water had subsided within the severely weathered rocks. This action had softened the rocks and caused a mass movement,” the MGB said.

The MGB recommended that residents and structures such as elementary schools and houses at Panpanan I and Sitio Libudon in Insubuan must be relocated to areas with flat to gently slopin terrain.

Residents must also avoid relocating near creeks, rivers and mountain foot slopes.

“These residents and structures, if not relocated, are facing real danger of landslides,” the DENR-MGB report said.

MGB geologists also advised communities along Maninila, Sibalom, Tipulu-an Rivers and other large creeks to be wary of the situation and prepare for evacuation during heavy rains or storms.

“The local officials of San Remigio must conduct continuous disaster preparedness training for barangay officials and residents to avoid victims of landslides in the future,” the agency said.

Brgy. Panpanan I and surrounding villages have rugged and mountainous topography with a steep slope angle, almost vertical to the headwaters of the Maninila River. The river is also the headwaters of other rivers and large creeks with waterfalls within the barangay.

The danger zone is also located 4 kilometers away from the West Panay Fault which is a major cause of earthquakes in Panay Island. If an earthquake occurs, the villages are at risk of disastrous landslides.

“At the time of evaluation, it was observed that there are several large landslides at the headwaters of Maninila River,” the MGB said.

The MGB evaluation also showed that majority of San Remigio town lies on the Antique Ophiolite Complex and late Oligocene and early Miocene bedrock.

This bedrock is composed of basalt with intercalated sandstone, siltstone, mudstone and conglomerate and other stone formation with cracks that could be penetrated by water thereby making it soft and prone to erosion and landslides.

“At the headwaters of Maninila River, the main rock types consist of severely weathered and highly jointed basalt-sandstone, siltstone-mudstone conglomerate called Panpanan Formation that is also prone to erosion,” MGB added.

It was observed that during heavy rains, rainwater and accumulated groundwater seeped through numerous joints/cracks of the severely weathered rocks. These rocks are made up of broken fragments, cemented particles of sand, silt, mud and loose soil.

“The presence of large volume of water separates these rocks/soil into its individual particles or fragments that makes it highly susceptible to mass movement. A mass of broken rocks and soil oversaturated with water located at the steep slopes will just naturally move or flow downward causing landslides.”

MGB Regional Director Leo Van Juguan said these conditions pose danger to communities below the mountain slopes, thus the local government should act at the earliest possible time. 

Juguan said residents of the five barangays must monitor their areas and immediately report ground movements to the MGB-DENR.

DENR Regional Director Benjamin T. Tumaliuan urged provincial and municipal government officials to review the geo-hazard maps provided by the MGB-DENR for inclusion in their disaster preparedness plans.

“The experience of flooding and landslides in Quezon and Leyte were the awakeners for all of us and it would be futile to blame any agency in case of disaster because of our unconcerned attitude to the havocs of nature,” Tumaliuan said.