MORE COMMUNITIES in Naga City, Cebu are seen to be at risk of natural hazards and could be required to permanently relocate, Environment Secretary Roy A. Cimatu said on Monday during a dialogue with the victims of the Sept. 20 landslides in Barangay Tina-an. The landslides that killed 78 and displaced more than 7,000 exposed the natural hazards in the city, according to a report prepared by state geologist Liza Soccoro J. Manzano. The disaster, she said, was a result of a “complex mass movement” in the city that is predominantly a karst terrain with numerous underground caves and sinkholes. “Subsidence in karst is one of the most dangerous geohazards due to its extreme unpredictability,” she said. Ms. Manzano explained that one of the causes of subsidence in karst is ground shaking due to earthquake, which she pointed as the main “culprit” of the tragic incident. But aside from the geology or topography of Naga and the earth tremors occurring there, other contributory factors are urbanization, industrialization, and quarrying. “Human activities, including quarry operations, that affect the change of the natural landscape are contributory factors to the complex landslide,” the report said. Barangays outside the active quarry operations that also showed signs of active subsidence are Cabungahan, Cantao-an, Upper Naalad, Mainit, Inayagan, and Inoburan it noted. With this, other households may also be recommended for evacuation, Mr. Cimatu said. In the meantime, the regional office of the Mines and Geosciences Bureau will announce by Oct. 25 who among the current evacuees can return to their homes and who needs to remain at evacuation centers while the relocation program is being worked out. — The Freeman