A powerful 7.8-magnitude earthquake off the coast of Mindanao in the southern Philippines has left at least 61 people dead, dozens missing and caused significant environmental changes, with parts of the seabed rising by approximately two meters, according to authorities.

Updated figures from the Philippines' disaster management agency showed that around 40 people remain missing as search and rescue operations continue in the affected areas.

The Department of Environment and Natural Resources said residents first noticed the geological changes two days after the quake, when portions of the coastline appeared to have expanded significantly. In some locations, the shoreline reportedly extended by as much as 200 meters.

According to the Philippine Institute of Volcanology and Seismology (PHIVOLCS), tectonic movements along the Cotabato Trench pushed up coastal sections of Sarangani and Davao Occidental provinces, exposing parts of the seabed that had previously been submerged.

PHIVOLCS said mapping surveys measured the uplift at approximately two meters.

Located about 50 kilometers off the southern Mindanao coast, the Cotabato Trench is one of the Philippines' most seismically active zones and has experienced frequent earthquake activity in recent years.

Environmental assessment teams dispatched to the affected area found extensive coral reefs and seagrass beds exposed above the waterline along large stretches of coastline. Images released by authorities showed broad sections of coral left stranded out of the water, with numerous fish and other marine organisms reported dead.

Officials warned that exposed corals and seagrass ecosystems were rapidly deteriorating, affecting reef fish, eels, shellfish and other marine species dependent on the submerged habitat.

Residents first noticed the environmental impact after dead marine life began washing ashore and emitting foul odors in several coastal communities.

Scientists say major earthquakes can occasionally cause permanent vertical shifts in coastal land and seabed levels, reshaping shorelines and significantly affecting local ecosystems.

The Philippines lies along the Pacific Ring of Fire, a region of intense seismic and volcanic activity where powerful earthquakes and volcanic eruptions occur frequently.(ILKHA)