Science and Technology Undersecretary Renato Solidum Jr. on Wednesday, July 27, said the major 7.0-magnitude earthquake in Abra was most likely generated by the movement along the Abra River Fault—an active fault, which last moved in 1868.
“Itong fault na ito ay known active fault na posible talagang kumilos at nasa range ng expected nating earthquake yung mga major earthquake events like magnitude 7 (This fault is a known active fault that may trigger major earthquake events, like the magnitude 7.0, which are in the range of our expected earthquake),” Solidum said in a press conference.
“Ang huling historical earthquake, mga magnitude 4 or less than 5, dito sa Abra River noong 1868 (The last historical earthquake, about magnitude 4 or less than 5, here in Abra River was in 1868),” he added.
Solidum, who is also the OIC of the Philippine Institute of Volcanology and Seismology (Phivolcs), pointed out that faults usually take “several hundred years” before it could produce a powerful earthquake.
Aftershocks, landslides likely after strong quake
Solidum advised the public to remain vigilant, as aftershocks may likely occur in the next few days or weeks.
“May aftershocks pa po yan. Usually sa ating experience, ang mga aftershocks napakarami sa first two days, three days, unti unti siyang bababa ang bilang. Pero posible pa po siyang magtagal ng mga ilang linggo (There are still aftershocks. Usually, in our experience, there are several aftershocks in the first two days, three days, until the number gradually decreases. But it is still possible for it to last a few weeks),” Solidum said.
“But with time, ay lumiliit yung numero. Minsan pasulpot sulpot, may mas mataas pa sa previous, normal po yan. But ang tendency niya, it would decrease with time (But with time, the number decreases. Sometimes intermittently, sometimes the magnitude is higher than the previous one, that’s normal. But the tendency is, it would decrease with time),” he added.
As of 11: 30 a.m., Phivolcs so far recorded 140 aftershocks following the 7.0-magnitude earthquake.
Solidum also warned against possible landslides because of the earthquake.
“Most likely, nakita ko na yung ibang mga pictures, marami pong landslide na mangayayari (I have seen some pictures, there are many landslides that will happen),” he said.
“Kapag dumating ang mga ulan at bagyo posible pa magkaroon ng landslide dahil gumalaw ang mga lupa (When rains and typhoons come, landslides are still possible because the ground has moved),” he added.
Solidum said that the 7.0-magnitude tremor is so far the “strongest on-land earthquake” since the 6.6-magnitude Masbate quake in August 2020.