June 8 Mindanao Quake Strongest Since 1976

The 7.8-magnitude earthquake that struck General Santos City on Monday, June 8, was centered at sea at a depth of 33 kilometers, about 32 km southwest of Maasim town in Sarangani province.

It was set off by movement in the Cotabato Trench and was the strongest since the same undersea depression triggered an 8.1-magnitude quake that whipped up tsunami waves on Aug. 17, 1976, said Teresito Bacolcol, the director of the Philippine Institute of Volcanology and Seismology (Phivolcs).

About 8,000 people died from that quake and tsunami waves of up to 8 to 10 meters (26 to 33 feet) that engulfed several towns and provinces, Bacolcol said.

Phivolcs was scheduled to commemorate the anniversary of the 1976 quake and tsunami in August by installing markers to remind vulnerable towns and cities of the need for constant vigilance, Bacolcol told The Associated Press.

A 1990 earthquake that also had a magnitude of 7.8 left more than 1,000 people dead, injured thousands and caused extensive damages in northern provinces and cities.

President Marcos deployed top defense-mitigation officials from Manila to help oversee search and rescue, the distribution of tens of thousands of food packs and construction materials to quake victims and assess damage to bridges, roads and other infrastructure.

The United States, a treaty ally of the Philippines, said it was coordinating with Manila and was ready to support Philippine response efforts. Other countries also expressed support.

The Philippines is often hit by earthquakes and volcanic eruptions due to its location on the Pacific “Ring of Fire,” an arc of seismic faults around the ocean.

The archipelago is also battered by about 20 typhoons and tropical storms each year, making it one of the world’s most disaster-prone countries.

Phivolcs recorded 23 strong aftershocks, with the strongest measuring magnitude 6.7, forcing some ?residents to spend the night in evacuation centers and tents.