GENERAL SANTOS CITY (MindaNews/24 July) – Three “slight to moderately strong” earthquakes rocked various parts of Mindanao early Saturday, sending some residents scampering out of their homes but no damages have been reported.
Bedoria Abdullah, science research specialist of the Philippine Institute of Volcanology and Seismology (Phivolcs) station here, said the first temblor was recorded at 6:08 a.m. at a magnitude of 6.9 at the Richter scale.
The quake’s epicenter was traced at 94 kilometers Southwest of Cotabato City and a depth of focus of 599 kilometers.
“It’s tectonic in origin or caused by the normal movement of the tectonic plates. It’s quite strong based on the recorded magnitude but we hardly felt it because of its depth,” she told MindaNews.
Abdullah said the quake was felt at Intensity 2 here and in the cities of Surigao, Davao and Butuan.
The second temblor, which was reported the first aftershock, was recorded at 6:52 a.m. at a magnitude of 6.7 and a depth of focus of 570 kilometers at its epicenter located 97 kilometers Southwest of Cotabato City.
Abdullah said the quake was felt at Intensity 4 in this city; Intensity 3 in Davao City and the towns of Padada, Malita and Sta. Maria in Davao del Sur; Intensity 2 in Matanao, Davao del Sur; and, Intensity 1 in Midsayap, North Cotabato.
Based on Phivolcs scale, an Intensity 4 earthquake is considered as moderately strong and felt generally by people indoors and by some people outdoors.
“Light sleepers are awakened. Vibration is felt like a passing of heavy truck. Hanging objects swing considerably. Dinner, plates, glasses, windows and doors rattle. Floors and walls of wood framed buildings creak. Standing motor cars may rock slightly. Liquids in containers are slightly disturbed. Water in containers oscillate strongly. Rumbling sound may sometimes be heard,” the Phivolcs earthquake intensity scale cited.
Abdullah said the second aftershock was recorded at 7:16 a.m. at a magnitude of 6.7 and 630 kilometers deep at its epicenter located 101 kilometers Southwest of Cotabato City.
She said Phivolcs stations here and in the cities of Cotabato, Kidapawan and Davao reported the third quake at Intensity 2.
“These are considered as normal temblors and there’s no need to declare any alert or warning on possible after effects like tsunamis,” she said.
Abdullah said the three succeeding earthquakes Saturday morning were so far the only recorded temblors in the area for this month. She added that the last recorded quake in the area was last June 28 at Intensity 2.
Engr. Milo Tabigue, of the PhiVolcs-Kidapawan substation, said the quake was also felt in the northern part of Mindanao and even in the Visayas and Luzon. (Allen V. Estabillo with reports from Malu Cadeliña Manar)