MANILA, Philippines – MANILA, Philippines (AP) — Three major undersea earthquakes struck the southern Philippines within minutes of each other early Saturday, but the temblors were too deep to cause any damage.
A magnitude 6.8 tremor shook the Moro Gulf off the island of Mindanao at 6:08 a.m. (2208 GMT Friday). It was centered about 60 miles (95 kilometers) southwest of Cotabato city at a depth of 380 miles (607 kilometers), the Philippine Institute of Volcanology and Seismology said.
A stronger 7.1 magnitude quake hit the same general location at roughly the same depth at 6:51 a.m. (2251 GMT Friday), followed at 7:15 a.m. (2315 GMT Friday) by a third, also of the same magnitude, the institute said.
The quakes also were too deep to cause a tsunami.
The temblors were hardly felt and lasted less than 10 seconds in Cotabato city, said local seismologist Reiner Amilbahar. "It did not cause alarm among the people," he said.
The Philippine archipelago lies in the so-called Pacific Ring of Fire where earthquakes are common. It is flanked by the Pacific Ocean to the east and the South China Sea to the west with undersea trenches — potential quake triggers — running alongside its coast on both sides.
A 7.9-magnitude quake generated tsunami waves in the Moro Gulf in the south in 1976, killing nearly 5,000 people. A major quake that registered a magnitude 7.7 in 1990 killed nearly 2,000 people on the main northern island of Luzon.