Being located along the Pacific Ring of fire as it is, the Philippines gets its fair share of volcanic activity and earthquakes. Even in the past year there have been quite a number of strong seismic tremors, with a significant portion of them happening in southern parts of the country. Earlier this month there was an earthquake of tectonic origin off the waters of Sulawesi in Indonesia. Further seismic activity in the area continued and this week, one particularly noticeable tremor from the sea shook the southern coast of Mindanao in the evening of Thursday.
CNN Philippines has it that the Philippine Institute of Volcanology and Seismology (PHIVOLCS) pinned down the origins of the earthquake that occurred at about 8:23 PM Philippine local time of January 21. Its epicenter was located at the Celebes Sea, just to the west of the Philippine Trench and 231 kilometers due southeast from Jose Abad Santos, Davao Occidental. As the relatively closest land area to the heart of the quake they were hit by a magnitude 7.1 shaking, the brunt of the tremors. Further off, Intensity V (“Strong”) was recorded in four municipalities of nearby Sarangani province – Malungon, Glan, Maitum and Kiamba – as well as the city of GenSan.
The rest of Sarangani, namely Alabel, Malapatan and Maasim, plus Sta. Cruz in Davao del Sur, Davao City, Digos City and Cotabato City all experienced Intensity IV (“Moderately Strong”). Next down in strength, Intensity III was registered in Zamboanga City, Cagayan de Oro City, Datu Sinsuat in Maguindanao and as far away as San Francisco, Southern Leyte. A little jiggling was felt in other parts of Mindanao as well as Camiguin Island, while in Eastern Samar only seismographs gave any indication that the tectonic earthquake affected that area at all.
PHIVOLCS gave no tsunami warning but warned of aftershocks, none of which reached the levels of the main quake although a total of 16 were detected by the time 4 AM of Friday, January 22. The depth of the tremor was determined to be 116 kilometers into the Earth’s crust underwater. Even with the 7.1 magnitude, the Jose Abad Santos local government reported no casualties or even noticeable damage in their infrastructure, something the municipal Mayor Jason John Joyce was thankful for. The no-damage assessment was seconded by Davao Occidental PDRRM Official Harry Camoro, who coordinated with provincial LGUs to confirm that nothing was destroyed.Image: Jason John Joyce Facebook page