MANILA, Philippines - Strong earthquakes shook several areas in Mindanao yesterday morning, but there were no reports of injuries or damage. Aftershocks were felt as far as Manila and Antipolo.
The Philippine Institute of Volcanology and Seismology (Phivolcs) said the first earthquake of magnitude of 6.9 occurred at 6:08 a.m.
The first earthquake’s epicenter was 94 kilometers southwest of Cotabato City, and was felt at Intensity 2 in Surigao City and General Santos City.
The second, at magnitude of 6.7, was felt at 6:51 a.m.
Its epicenter was traced to 97 kms southwest of Cotabato City, and was felt at Intensity 2 in Butuan City and Surigao City.
The third and the strongest, at magnitude 7.1, was recorded at 7:15 a.m. with epicenter at 98 kms southwest of Cotabato City.
The last earthquake was felt at Intensity 4 in Tanjay City and San Jose City, Negros Oriental; Intensity 3 in General Santos City; Lingig, Surigao del Sur; San Jose and Hamtic, Antique; Irosin in Sorsogon and Sorsogon City; Intensity 2 in Cotabato City; Kidapawan City; Dipolog City; Tacloban City; Davao City; Legazpi City; Cagayan de Oro City; Cebu City; Dumaguete City; and at Intensity 2 in Manila and Antipolo.
While the epicenters of the quakes were in the sea, residents of Mindanao strongly felt the tremors, which were of tectonic origins, according to Philvolcs.
But a US Geological Survey (USGS) report showed the first earthquake had a magnitude of 7.3, the second 7.6, and the third 7.4.
Phivolcs seismologist Ishmael Narag said they would be monitoring Cotabato City closely in the next 24 hours for aftershocks.
Narag also said that since the earthquakes were deep, they would not trigger a tsunami.
Office of Civil Defense (OCD) head retired Army Gen. Benito Ramos called on residents in southern and western Mindanao to stay calm.
“There’s no need to be alarmed, so don’t panic. We haven’t monitored any forthcoming tsunamis,” Ramos said.
“On the surface, it was only felt at intensity 4.9. Magnitude is different from intensity. Magnitude is underneath quake force while intensity is above the surface. So it could be 6.9 magnitude but only intensity 4.9 on the surface. So it wasn’t that strong but it did cover wide areas in Mindanao,” Ramos explained.
He also downplayed reports that the earthquakes damaged telecommunication lines in some parts of Mindanao.
The Philippines sits on the Pacific “Ring of Fire” where continental plates collide, causing frequent seismic and volcanic activities.
On Aug. 16, 1976, a tsunami caused by a powerful earthquake killed between 5,000 and 8,000 people in the Moro Gulf region in Mindanao.