THE chief of the Philippine Institute of Volcanology and Seismology (Phivolcs) on Monday said there was no cause for alarm over the coastal uplift which was triggered by the magnitude 7.8 earthquake in the Cotabato Trench last June 8.
“On a positive note, the land area has increased including the beachfront,” Phivolcs director Teresito Bacolcol told The Manila Times via Viber interview.
Bacolcol said it was not necessarily alarming, but it was possible that the marine ecosystem could have been affected when the seabed shifted by as much as two meters (6.6 feet).
Coral reefs, seagrass beds, and reef flats that were once underwater could become permanently exposed to air and sunlight, he said.
Bacolcol said the shift may also affect ports and fish landing areas, making it more difficult for boats to dock.
The Cotabato Trench, located in the Pacific Ocean directly off the southwestern coast of Mindanao, is a highly active fault system capable of generating massive earthquakes and destructive tsunamis, he said.
The coastal uplift was not new. In 2013, the magnitude 7.2 earthquake in Bohol exposed previously submerged coral reefs in Maribojoc.
Bacolcol said the phenomenon was also part of the long-term geological processes that continue to shape the Philippine archipelago.
“That is why we have mountains that are made of limestones. These limestones were previously undersea but were pushed upwards through repeated earthquakes (probably thousands of such events in a long period of time) such as the Cotabato earthquake,” he said.
Residents in Barangay Pangyan in Glan town, Sarangani, and in Jose Abad Santos in Davao Occidental first reported the geological phenomenon two days after the tremor.
The residents feared that the shift in the seabed could release toxic fumes from decaying sea life.
As of Monday, the National Disaster and Risk Reduction Management Council said the number of families affected by the Mindanao earthquake has climbed to more than 176,000, while authorities reported at least 65 deaths and over 1,400 injuries.
