Fri, 18 Sep 2020

Not 3 but 4 strong quakes rocked Mindanao in October

Philippine Information Agency
16 Nov 2019, 08:38 GMT+10

DAVAO CITY Nov. 15 (PIA) A senior research analyst of the Philippine Institute of Volcanology and Seismology clarified that there were four earthquakes and not three that happened in October 16, 29 and 31.

Jeffrey Perez, senior research analyst of the Phivolcs told members of the response cluster of the Regional Disaster Risk Reduction and Management Council XI that there were four strong earthquakes that happened in a series namely magnitude 6.3 on October 16, magnitude 6.6 on October 29 and magnitude 6.1 two hours later, and magnitude 6.5 on October 31.

He said he could relate to the occurrence of the last three quakes because he actually felt them while investigating the October 16 quake.

"It is now called the October 2019 series of earthquakes in North Cotabato composed of four earthquakes with magnitude six and above," Perez said.


He said the series of earthquakes resulted in the destruction of many houses and buildings and landslides in the barangays of Makilala, Bansalan, Magsaysay and Digos City whose residents needed to be forcibly evacuated.

Perez said Kiblawan also reported the occurrence of landslide in its area.

He expressed dismay that many of the destroyed buildings housed the Municipal Disaster Risk Reduction and Management Office like in Makilala and Matan-ao.

Perez said the government's system of responding to displaced persons did not do well in Makilala given that its mayor is new and with a new DRRM officer.

"They were all overwhelmed with the situation. We need to evaluate the Executive Order on disaster management given that many of the responders then were also victims," Perez said.

He said the large number of people was too much for the new MDRRMO and the mayor to handle.

Perez also observed that the situation in the affected areas needs mutual aiding, wherein government agencies responding to the situation must come from the outside since homegrown employees were also victims of the disaster.

He also said that the totally collapsed houses and buildings were substandard.

"From magnitude 6 to 6.9, the classification of the tremor is a strong earthquake. Magnitude 5 to 5.9 is moderately strong earthquake. Magnitude 7 is greatly strong earthquake. Many substandard structures collapsed due to the strong earthquake," Perez said.

He suggested to train the local masons and carpenters the standard masonry and carpentry.

Perez said there was one sitio where all the houses collapsed.

"Incidentally, they only have one carpenter who constructed the houses in that area," he said.

Perez also observed that many public schools were destroyed by the series of earthquakes.

He said these schools range from the K-12 school buildings and Yolanda-type schools.


All of the recent earthquakes were said to be tectonic in origin.

He narrated that both the first earthquake in October 16 at magnitude 6.3, second and third earthquakes, in October 29 with a magnitude 6.6 and magnitude 6.1 respectively happened near Tulunan, North Cotabato due to the movement of the M'lang fault.

Perez said the earthquake with a magnitude at 6.5 in October 31 happened in Makilala, North Cotabato as epicenter due to the movement of the Makilala-Malungon fault.

The first earthquake greatly affected Tulunan and Magsaysay but the earthquake in October 31 devastated many houses in Makilala and Kidapawan since the source of the earthquake is near to these areas.

"The aftershocks will still be there until they are gone but we do not remove the possibilities that other faults in the area will also move and the occurrence of a stronger quake as manifested by the October 16 and October 29 occurrences. We have reached as high as 4,000 aftershocks so far," Perez said.

The Phivolcs found five faults in North Cotabato Fault System namely M'lang Fault, Makilala Fault, Makilala-Malungon Fault, North Colombio Fault and the South Colombio Fault.

The series of tremors could be caused by stress transfer characterized by the domino effect in the movement of earthquake faults.

Perez said the earthquake in October 16 in Tulunan, could have affected the October 31 earthquake in Makilala.

He dispelled fears that the tremors in North Cotabato might affect the Davao City Fault System and the behavior of Mt. Apo.

The possibility could be nil since the distance of North Cotabato and Davao City are far from each other.

He said all the tremors that jolted Mindanao in October were tectonic in origin which means the movement occurred several kilometers underground and not volcanic attributing to Mt. Apo and other volcanos like Mt. Matutum and Mt. Parker in South Cotabato and Mt. Leonard in Compostela Valley.


Phivolcs says that a volcanic eruption has many indicators before an explosion and can give enough time for the residents to vacate.

To cope with the earthquake, he recommended the actual observance of duck, drop, cover and hold in case of another felt earthquake.

Damaged building and infrastructures should be inspected by engineers and should not be used unless assessed to be safe.

There is also the need to conduct preemptive evacuation on areas with tension cracks to prevent a landslide.

He said buildings must be constructed in conformity with the National Building Code and check on the gap between the issuance of building construction permits and monitoring of building construction.

Meantime, Retired Major General Manuel Ochotorena, director of the Office of Civil Defense XI and chair of the RDRRMC XI reported to the National Disaster Risk Reduction and Management Council regarding the efforts and needs of the areas affected by the earthquakes in its areas of jurisdiction..

In a teleconference, he underscored the need for potable water in the affected areas namely Bansalan, Magsaysay and Matan-ao.

Harold Cabreros, chief of the operations center of the NDRRMC concurred for the immediate purchase of a waterline to be used in the evacuation site of Balnate.

Ochotorena also cited the need for solar power bulbs to illuminate the evacuation areas and to light its passage at night.

"It is to prevent crime particularly abuse of women and children," he said.

Ochotorena assessed that there is enough supply of relief food packs in the evacuation camps due to the outpouring response in the form of food stuff, tarpaulins, tents and bottled water from the government and the private sector.

He said the food packs of the DSWD will last for three days and are good for a family of five.

Ochotorena said the Emergency Operation Center of the OCD XI intends to send rice and viand together to ensure right pairing of needs for the evacuees.

He also aired the importance of having official replacements in evacuation camp management.

Ochotorena aired his suggestion to Fe Subong, director of the DSWD XI regarding the need for graduating Social Work and Psychology students to conduct exposure in camp management on real evacuation camps.

He also conveyed the needs to the Department of Health like medicines, more latrines and portalets to prevent the outbreak of diseases and come up with Health Cluster Plan to sustain the prolong stay of families inside evacuation centers especially those who were forcibly evacuated due to tension cracks. (PIA XI-Joey Sem G. Dalumpines)

More Manila News

Access More

Sign up for Manila News

a daily newsletter full of things to discuss over drinks.and the great thing is that it's on the house!