Philippines earthquake lifts seabed by up to two metres, exposing coral reefs and killing marine life
A 7.8 magnitude earthquake that struck the southern Philippines on Monday lifted the ocean floor by as much as two metres in coastal areas, exposing coral, killing reef fish and prompting resident fears of toxic fumes from decomposing marine life.
Devastating human toll
The 7.8 magnitude tremor that hit Mindanao island on Monday has killed at least 61 people and left 40 missing, according to the national disaster management agency. Hundreds more were injured. The figures were updated on Sunday as search and rescue efforts continued in the southern Philippines.
Coastal uplift surprises residents
Two days after the quake, people living along the coast of Sarangani and Davao Occidental provinces reported a ‘coastal uplift’ phenomenon. The shoreline extended seaward by as much as 200 metres in some spots, exposing the seabed that had been submerged.
Approximately 2m was the mapped uplift.
A team dispatched by the environment department found long stretches of shoreline, coral reefs and seagrass beds laid bare.
Marine life exposed and dying
The sudden exposure has triggered a mass die-off. Corals and seagrass beds that were previously underwater began to bleach and rot, along with the fish, eels, clams and other shellfish that inhabited them. Images released by authorities show large areas of coral topped with dead fish and other aquatic life.
These exposed corals and seagrass beds had begun dying off alongside their resident organisms such as reef fishes, eels, clams, and shells.
Tectonic shift triggered by Cotabato Trench
The phenomenon was caused by a displacement along the Cotabato Trench, a subsea fault lying about 50 kilometres off the coast of southern Mindanao. The trench is known for frequent seismic activity, including a swarm of thousands of mostly small earthquakes recorded in January. This week’s slip pushed upward sections of the Sarangani and Davao Occidental coastal seabed.
- 7.8 magnitude earthquake strikes Mindanao island, killing at least 61 and injuring hundreds.
- Residents report coastal uplift, with shoreline extending as far as 200 metres in Sarangani and Davao Occidental.
- Environment ministry confirms seabed rose up to 2 metres, exposing coral and marine life now dying off.
Fears of health risks from decay
Local residents contacted authorities amid concerns that fumes from the rotting marine life could pose a health hazard. Officials are assessing the scale of the affected area, which remains difficult to survey because of its size.
