The Mines and Geosciences Bureau (MGB) 7 classified Barangay Alpaco, Naga City, south of Cebu as high landslide susceptibility, in its August 2011 geohazards assessment as there are areas usually with steep to very steep slopes, underlain by weak materials and with numerous old or inactive landslides.
This came after a team of geologists composed of Maria Elena S. Lupo and Josephine T. Aleta conducted a landslide assessment and mapping in 2011 consistent with the government’s efforts aimed at reducing, if not, totally mitigating the destructive effects and impacts of natural hazards on the populace.
The city government of Naga in its letter dated February 20 requested the immediate inspection of the reported cracks and partial cave-in of a road estimated at one meter wide in the hilly village in Barangay Alpaco.
Results of the 2011 assessment indicated that Barangay Alpaco had mostly limestone materials characterized as typically porous and poorly bedded which has high absorptive capacity.
Mapped and assessed in 2011, the team recommended the monitoring of progress of mass movement and report to the MGB or municipal and barangay officials, observe for saturated ground or seeps and sunken or displaced road surfaces, develop early warning system, and install slope protection measure along the creek embankment, which is affected by scouring during heavy rains.
MGB-7 Regional Director Loreto B. Alburo said it will send anew a team of geologists to check the area acting on the request of the city government of Naga.
Based on the initial assessment, the incident may have been attributed due to the combination of several factors such as heavy rainfall, the type of soil being mostly limestone, presence of ground cracks which become bigger due to the 6.9 magnitude earthquake and afterschocks last February 6.
Aside from Barangay Alpaco, five other barangays in Naga City which have been rated as high landslides susceptibility are Tagjaguimit, Balirong, Mayana, Naalad, and Cogon.
Meanwhile, eight barangays with moderate to high landslide susceptibility include Cantao-an, Lutac, Lanas, Bairan, Patag, Jaguimit, Uling, and Tina-an.
As to moderate to high vulnerability to flooding, twenty barangays, namely, Lutac, Lanas, Bairan, Patag, Balirong, Uling, Tina-an, Inayagan, Poblacion North, Pangdan, Tangke, Colon, Mainit, Jaguimit, Tuyan, Naalad, East Poblacion, Central Poblacion, West Poblacion, and Langtad.
“Communities who are living near or at the foot of the mountain or riverbanks to be on guard and cautious at all times as we don’t know when heavy rains will occur as many geohazards are rain-induced,” Alburo added.