Canaman fault line not yet established -Phivolcs

By Jason B. Neola


The Philippine Institute of Volcanology and Seismology (Phivolcs) in Bicol has yet to find out whether the earthquake swarm hitting Naga and most of Camarines Sur towns since Thursday, Oct. 14, can be traced to a fault line in Canaman, a neighboring town of the city.


In an interview via zoom with Bicol Mail on Monday,Oct. 18, Dr. Paul Alanis of Phivolcs, however, said that the series of tremors can be attributed to a tectonic plate movement or the large-scale motion of the plates beneath the grounds.


“But we cannot say at this very moment that this earthquake swarm is caused by a fault line that may be located in Canaman although it is possible that a blind fault has developed in that area and that’s what we are determining at present,” he said.


Alanis, who works as science research specialist at Phivolcs, said that “most likely, the quakes occurred because of the Philippine Fault Zone in which a major inter-related system of geological faults throughout the whole of the Philippine Archipelago works, primarily caused by tectonic forces compressing the Philippines into what geophysicists call the Philippine Mobile Belt which include the Masbate fault.”

DUCK, COVER, AND HOLD Public school children from the Naga Central School 2 participate in an earthquake drill organized by the Naga City government in collaboration with the Bureau of Fire Protection (BFP) last June 28, 2019. The exercise is expected to become a usual sight in malls, offices and other places frequented by the public soon as the city government of Naga endeavors to ready its constituents for the occurrence of earthquakes that bedevil the city the past several days. JBN/REYBAYLON/CEPPIO file photo


He said the zone also covers the province of Camarines Sur specifically the towns between the municipalities of Pasacao and Balatan including some parts of Albay province.


He also ruled out the idea that Mt. Isarog has something to do with the phenomenon since the earthquake swarm traced from Canaman is tectonic or triggered by the movement of plates and not by volcanic activity like magma flow.


The “Big One”


In last Tuesday’s regular session of the Sangguniang Panlungsod, Phivolcs was asked via zoom about the possible occurrence in the locality of the so-called “The Big One.”


Ishmael Narag, chief of Phivolcs’ Seismology Division, said the area where the current swarm originated does not have the capability anymore to produce tremors of higher magnitude than what it has generated.


Narag, however, said the situation does not apply to other fault lines located in other parts of Bicol region, which are capable to generate quakes of much powerful magnitude.


The series of earthquakes that began to be felt on Thursday last week was recorded in varied magnitudes of 4.3, 3.2, and 2.5.


The Big One, is a disaster imagination of a 7.2 magnitude earthquake feared to happen in the Philippines that lies on the Pacific Ring of Fire, home of several tectonic plate boundaries.


Narag and Alanis made their presence available via zoom at the city council after Councilor Joselito S.A. del Rosario sent a letter to Undersecretary Renato Solidum Jr., of the Department of Science and Technology (DOST) last Monday, Oct. 18, requesting the two Phivolcs officials to shed light on the occurrences of tremors.


Solidum immediately responded to Del Rosario’s request by directing the two Phivolcs officials in Bicol to appear on the following day at the Sangguniang’s regular session.


With regard to Mt. Isarog, Alanis assured the council that Phivolcs, which keep a constant monitoring on the mountain, is not seeing any abnormality on the highland, which has active fumaroles and hot springs. Mt. Isarog has an elevation of 2,000 meters above mean sea level.