EXPLAINER: What is a coastal uplift?

NO LONGER SUBMERGED. A coastal uplift was observed in parts of Sarangani and Davao Occidental following a magnitude 7.8 offshore earthquake on June 8. PHOTO COURTESY OF PROVINCIAL ENVIRONMENT AND NATURAL RESOURCES OFFICE-SARANGANI

MANILA, Philippines — The coastlines in Sarangani and Davao Occidental are now the focus of scientific investigations after the magnitude 7.8 earthquake that struck Mindanao on June 8 exposed coral reefs that were once submerged.

As the Philippine Institute of Volcanology and Seismology (Phivolcs) explained, the phenomenon is called coastal uplift, a vertical deformation of the coast in response to the upward and downward movement of the crust along a fault or subduction zone.

Phivolcs said coastal uplift or subsidence may happen suddenly during an earthquake, or coseismic, or gradually during slow progressive deformation of the crust, or interseismic.

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