Other areas prone to landslide

CEBU, Philippines — Aside from Naga City, other upland communities in central and southern Cebu have been found susceptible to earthquake-induced landslides, said an official of the Philippine Institute of Volcanology and Seismology (PHIVOLCS).

Engr. Robinson Jorgio, officer-in-charge of the institute’s station in Lapu-Lapu, Cebu, said the potential hazard is present in mainland Cebu because it is dominantly underlain with limestone, which is dissolved easily by water that eventually creates underground caves or sinkholes.

Because of this, he urged engineers and developers strongly to undertake “ground exploration” before building structures.

“Earthquakes can cause natural hazards everywhere like tsunamis in coastal areas, or liquefaction in plain terrain or landslide in mountains. But you just have to apply the right engineering measures or other instruments to minimize the adverse effects,” he told The FREEMAN.

Before building houses, for example, precautionary methods such as the geo-technical exploration have to be employed to avoid critical or high risk areas or to ensure the safety of people.

The September 20 tragedy in Naga City exposed natural hazards that were unknown previously to many residents and even to the city mayor.

Experts revealed recently that the city sits on a karst terrain with numerous sinkholes and underground caves that gradually degraded or weakened because of the earthquake swarms that shook the city.

The series of seismic activities also disrupted the subterranean flow of groundwater.

Quarry

Meanwhile, the Department of Environment and Natural Resources is set to send a team of geologists to hold a thorough geo-hazard survey in two active quarrying operations in Naga City.

Environment Secretary Roy Cimatu has directed the Mines and Geosciences Bureau to assess the operations of JLR Construction and Aggregates, Inc. in Cogon and the Quarry Ventures Philippines Inc. in Tagjaguimit as soon as possible.

The two quarry firms were allowed to operate again earlier this month after MGB completed its initial safety and geo-hazard survey there. For QVPI, the suspension of operations was lifted except for one parcel of its permit area.

Other Areas

Jorgio said there are other uphill areas outside Naga City that are marked red, which means they are also vulnerable to earthquake-induced landslides.

Most of these areas are located in central and southern Cebu, specifically in mountain barangays.

 At least 10 local government units have asked the Provincial Disaster Risk Reduction and Management Office (PDRRMO) to reassess their preparedness plans.

“Daghan na ang nagrequest kay mahadlok sila mapareha sa Naga,” said PDRRMO Spokesperson Julius Regner.

Most of the LGUs that requested for reassessment have quarry activities in the locality, including Minglanilla, Naga, San Fernando, Argao, Dalaguete, Alcantara, Consolacion, Compostela, Carmen, Tabogon, Medellin, Pinamungajan, Asturias Danao City, and Talisay City.

The towns of Alegria, Compostela, Consolacion, and Tuburan have also made the same request.

Regner said all local government units in the province have received geohazard maps from the Mines and Geosciences Bureau. However, guidance on what measures to take on top of MGB recommendations and validation if these are still applicable at present are things the PDRRMO may help the LGUs with.

PDRRMO has visited Tuburan town at least three times to check the area, especially that a school is situated near a quarry site.

In Talisay City, 15 households were evacuated from an area near a quarry site because rocks have started falling off cliffs. – JMO (FREEMAN)