THE Philippine Institute of Volcanology and Seismology (Phivolcs) said Ragay town in Camarines Sur is experiencing an earthquake swarm that started on Saturday.

Phivolcs on Sunday explained that an earthquake swarm is a short-lived sequence of minor to light earthquakes.

According to the agency, they recorded 45 earthquakes as of 3 pm on Sunday, with 34 of these felt.

The highest magnitude was 4.4, which was felt at intensity 5 in Ragay municipality. Intensity 5 is considered strong, with ground shaking generally felt by most people and hanging objects swinging violently.

Phivolcs said an earthquake swarm may vary in duration and outcome. One scenario is a short-duration burst of earthquake activity that may last for a few days, similar to the two earthquake swarms that occurred in Camarines Sur on December 13, 1993 and October 14 to 16, 2021.

It said another possible scenario that should not be discounted is that the earthquakes may be a precursor to a larger magnitude earthquake.

Phivolcs director Teresito “Toto” Bacolcol said with at least seven significant earthquakes with magnitudes ranging from 6 to 7.4 that occurred in the Camarines Sur town and its vicinity from 1811 to the present, the most damaging was the magnitude 7 that occurred on March 17, 1973.

Citing data, he said Camarines Sur is a seismically active region because of the presence of active faults that include the Legaspi Lineament and offshore segments of the Philippine Fault in Ragay Gulf.

Bacolcol said even if a larger magnitude earthquake would occur, there would be no worry for tsunamis since the epicenters of these earthquakes are situated inland.

The Phivolcs chief also ruled out volcanic activity from the earthquake swarm.

“The earthquake swarm is clearly tectonic in origin. The closest volcano, Labo Volcano, is approximately 15 kilometers away, and is considered potentially active. The nearest active volcano is Isarog Volcano, situated around 60 kilometers away,” he added

Phivolcs advised people in affected communities to protect themselves from strong quakes by following the standard “drop, cover, and hold” practice, and to secure heavy furniture, appliances, and hanging objects.

It also called on local authorities to inspect buildings and infrastructure for signs of damage.