More than a week after a strong earthquake jolted Cebu, another powerful magnitude 7.4 temblor struck off the coast of Manay, Davao Oriental at 9:43 a.m. yesterday, shaking wide areas of Mindanao and the Visayas, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).
At least three people were reported killed as of last night while many houses and buildings including schools sustained heavy damage.
The quake, which originated 43 kilometers northeast of Manay at a depth of 23 kilometers, prompted Phivolcs to issue a tsunami warning for several eastern coastal provinces before it was lifted in the early afternoon.
The quake was felt strongest at Intensity 5 in parts of Davao de Oro, including Compostela, Maco, Mawab, Monkayo, Montevista, Nabunturan and Pantukan; in Davao del Norte, covering Asuncion, Braulio E. Dujali, Carmen, New Corella, Panabo City, Island Garden City of Samal, Santo Tomas and Tagum City as well as in Davao Oriental’s Cateel and Mati City.
Strong shaking was also reported in Davao City, Davao Occidental’s Jose Abad Santos, and parts of Cotabato, South Cotabato, Sarangani, Surigao del Norte and Agusan del Norte, including Kidapawan, Koronadal, Tupi, Tampakan, Alabel, Glan, Malungon, Butuan, Claver, Gigaquit and Mainit, along with General Santos City.
Moderately strong tremors (Intensity IV) were recorded in Tacloban City and several municipalities in Bukidnon, Davao del Sur, Davao Occidental, Cotabato, Sarangani, South Cotabato, Surigao del Norte and Cotabato City, while Intensity III shaking reached parts of the Visayas, including Eastern Samar, Leyte, Ormoc City, Northern Samar, Samar and Southern Leyte, as well as Iligan, Cagayan de Oro, Bukidnon and Sultan Kudarat. Weaker intensities were experienced in Negros Oriental, Biliran, Sorsogon, Zamboanga Peninsula, and parts of South Cotabato, where residents reported gentle swaying movements.
Instrumental readings showed Intensity V in Davao City, Nabunturan, Kidapawan, Koronadal, Tupi, Alabel, Malungon and Hinunangan, Southern Leyte, while Intensity IV was recorded in Cebu City, Malaybalay, Digos, Surigao City, Bislig and General Santos City.
Lower intensities were registered across the central and southern Philippines, including parts of Leyte, Bukidnon, Cebu, Northern Samar, Zamboanga and Iloilo.
Tsunami alert
The US Tsunami Warning System issued an advisory shortly after the earthquake, warning that hazardous waves could threaten coastal areas within 300 kilometers of the epicenter. It initially warned of possible tsunami waves in the Philippines, Indonesia and the island nation of Palau following the earthquake.
In Tandag, Surigao del Sur, the Tsunami Detection Station recorded a 30-centimeter wave height at 10:20 a.m., confirming minor sea-level changes.
At 1:43 p.m., Phivolcs lifted the tsunami warning, saying any potential tsunami effects ‘have largely passed.’
Science Secretary Renato Solidum Jr. explained that the relatively low tsunami height despite the earthquake’s strong magnitude was due to the type of sea floor movement involved.
‘The height of the tsunami is related to the actual vertical displacement of the sea floor as a result of subduction in trenches,’ Solidum said.
He also clarified that the recent quakes in Cebu, La Union and Davao Oriental are unrelated. ‘There is no connection as the faults that triggered the Cebu and La Union quakes and the Philippine Trench that caused the quake in Davao Oriental are not connected and far apart,’ he added.
Following the Office of Civil Defense’s issuance of a Red Alert Status for the Davao Region, the Davao City CDRRMO likewise raised its alert status to Red, prepositioning all emergency assets in preparation for possible aftershocks.
As of 5 p.m., a total of 339 aftershocks were recorded. Of these, 88 aftershocks have been plotted, while 13 were reported as felt by residents. The recorded magnitudes ranged from 1.3 to 5.8, based on data from the Mati (Davao Oriental) reference station.
Casualties
The strong earthquake that jolted Davao City and nearby areas on Friday morning killed three people and injured over 300 individuals.
An 80-year-old man died after a concrete wall collapsed on him during the earthquake. Another victim, a 54-year-old woman, was killed by a falling wall. Details from the third fatality have yet to be determined because the victim is from a far-flung barangay in Mati.
The City Disaster Risk Reduction and Management Office (CDRRMO)-Central 911 has responded to a total of 347 individuals who experienced fainting or sustained minor injuries. ‘All patients have received proper medical attention and are now in stable condition,’ it said in a statement.
The City Engineer’s Office (CEO), in coordination with the Department of Public Works and Highways, has completed structural assessments of Bankerohan Bridge, Bolton Bridge, Davao River Bridge and San Rafael Bridge.
According to the CEO, no major structural damage was found and all four bridges are declared safe for vehicular traffic.
Structural damage was reported at Mapua Malayan Colleges Mindanao and Ateneo de Davao University.
The Bureau of Fire Protection Region XI reported a chemical spill at the 6th floor of San Pedro College, which they already contained.
Several establishments closed down to check for damage from the shaking as there were buildings that sustained cracks and fallen ceilings.
Work in all government offices in the city was suspended, except for offices performing safety and security, health, social services and disaster and emergency response services.
Power interruptions were reported in some parts of Davao City and nearby municipalities shortly after the quake, but services have since been restored in most areas.
Office of Civil Defense deputy administrator for administration Bernardo Rafaelito Alejandro IV said there were initial reports of minor structural cracks in some schools in Cagayan de Oro and Iligan City, while there was a reported landslide in Camiguin.
Power outages were reported in Misamis Oriental.
‘There were observed cracks along Francisco Bangoy International Airport but the airport is still operational. There were no cancelled flights in Davao City,’ Alejandro said.
Damaged schools
The Department of Education said that at least 29 schools suffered major damage following the earthquake in Davao Oriental.
The DepEd added that 173 schools recorded minor damage while 12,399 others were exposed.
It added that reports from the Incident Management Response System from Regions 9, 10, 11, 12 and CARAGA indicate that 9,923 learners and 490 teachers were affected.
The DepEd added that five learners and a teacher were injured during the strong quake.
Coincidence
Although Metro Manila and surrounding areas are already ripe for the ‘Big One,’ the series of strong earthquakes that recently rocked different parts of the country is not a precursor for such an event, according to Phivolcs director Teresito Bacolcol.
In an interview with ‘Storycon’ on One News, Bacolcol described the strong earthquakes that recently jolted Cebu, La Union and Davao as ‘coincidence.’
‘Every day, we record at least 30 earthquakes. There’s always this possibility that several could occur close together because we have 180 active fault segments and six trenches,’ he said.
‘What happened in Cebu was generated by the Bogo Bay fault, the one in La Union (on Thursday) was generated by the Philippine fault and the one (on Friday) was generated by the Philippine trench,’ he added.
Bacolcol maintained that these earthquakes are not a ‘precursor’ of the Big One, a projected scenario when a magnitude 7.2 or stronger earthquake would hit Metro Manila due to a movement of the Marikina Valley fault.
Still, he stressed the need to be prepared for the possibility of strong earthquakes as the Philippines is tectonically and seismically active.
Forced evacuation
For its part, the Department of the Interior and Local Government (DILG) on Friday directed local officials in parts of the Visayas and Mindanao to conduct forced evacuations in coastal communities following the earthquake in Davao Oriental.
The DILG ordered local government units in Eastern Samar, Southern Leyte, Leyte, Dinagat Islands, Surigao del Norte, Surigao del Sur and Davao Oriental to immediately evacuate residents near shorelines and move them to higher ground or inland areas.
Boat owners were advised to secure their vessels or stay in deep waters, while residents in coastal houses were urged to move further inland.
Class, work suspension
The University of the Philippines Mindanao has suspended face-to-face classes until Monday following the quake.
UP Mindanao gave assurance that it is working with diligence to assess all buildings, adding that it will issue further announcements once inspections are completed and on-site work is confirmed safe to resume.
UP Cebu said the magnitude 7.4 earthquake in Davao was felt in Cebu City, adding that intensity 4 was recorded in the province.
‘In response, the University of the Philippines Cebu conducted an initial visual assessment of its facilities. The Lahug Campus remains safe, with no new structural damage observed following the inspections made after the September 30 earthquake,’ the UP Cebu said.
Classes in all levels, both public and private as well as work in government offices, were suspended in Davao City and Sultan Kudarat.
The Davao City local government also ordered the suspension of classes and work in government. In central Mindanao, officials immediately cancelled classes in all schools after the quake.