The Mines and Geosciences Bureau (MGB) 7 of the Department of Environment and Natural Resources (DENR) recommended the temporary suspension of classes of Don Emilio Canonigo Memorial National High School (DECMNHS) in Barangay Pangdan, Naga City, Cebu.
This developed after a 1.3-hectare landslide affected area occurred last July 31 past 12:00 noon which is about 30 meters away from the said school with 345 students and 16 teachers.
“Our geohazards mapping and assessment team led by chief geologist Al Emil Berador came with a landslide susceptibility rating of very high or critical which means that this an active landslide zone and still moving or continue to slide,” said MGB 7 Regional Director Loreto B. Alburo.
Alburo said we wrote a letter to DECMNHS principal Nicandra Arañas yesterday (August 1) to ask her to continue suspending classes in the meantime that the unstable soil or rock mass at the upper part or head of an unstable or potentially unstable slope is still there.
The classes have been suspended last July 31 at around 2:30 in the afternoon right after the recorded landslide happened.
Upon investigation, the three-member team noted an old landslide, with canal or gulley in between the two hills, characterized as very steep slope with an approximate affected area of 1.3 hectares. The type of soil is mostly tuff which is highly fractured materials.
With this, the MGB 7 issued a landslides threat advisory after the ocular inspection last July 31 and it was received by Barangay Councilor Alvin Alinsonorin with about seven recommendations.
The recommendations are the following: reduce the slope height or inclination; implement slope stabilization measures with the Naga City Mayor’s Office and Apo Cement Corporation (APC); continuously monitor the movement; inform and warn the residents to become vigilant of the situation especially those residents near the south wall of the affected area; cordon off and prevent people from venturing near the affected site; temporarily evacuate residents along the south wall during heavy rains.
Alburo received the information on the incident after a phone call from APC’s Ariel Lazarte last July 31. On that day, the APC deployed a backhoe to start moving down the unstable slope.
“We heard a different sound and after the sound we saw small rocks started to fall at around 12:30 in the afternoon,” according to one of the residents who witnessed the movement.
“Incessant rains there may be one of the factors that push the landslides,” Alburo added.
The mining firm set out yesterday one backhoe and one bulldozer to speed up the slope stabilization measures by cutting work and removing unstable soil materials which is expected to be completed Wednesday.
In a report by the team, there were a number of tension cracks surrounding the slope with highly fractured tuff materials. Also, it observed an estimated volume of about 700,000 cubic meters to be toppled down in order to stabilize the slope.
In an interview with Barangay Pangdan Barangay Captain Aurelio Alinsonorin and some residents, they said that there were successive heavy rains which took more than four days before a recorded slide last July 31. There were discussions on the hazards present over the area and the need to remove down the soil materials so that it will not endanger the lives and property.
In a related development, some 26 sitios in 17 barangays in Naga City, Cebu are either categorized or rated as high to very high to landslides and flooding in a geohazard assessment using a 1:10,000-scale by the MGB 7.
The results of the mapping showed out of 18 sitios which were classified as high risks for landslides, eight and ten sitios were rated as very critical and critical or high, respectively.
“Our regular reminder or advisory to the local chief executives to use the geohazards maps and the findings including recommendations in determining the appropriate interventions or measures they will take,” said DENR 7 Regional Executive Director Dr. Isabelo R. Montejo.
Montejo said it is better to pro-active always considering the danger of these geological hazards like landslides and flooding to the communities.