Phivolcs: Bukidnon new fault line emerges, LGUs’ support sought

MALAYBALAY CITY (Bukidnon News/20 September) It’s high time for local governments in Bukidnon to walk the talk and fund fault studies in their areas as a new fault line is observed in upland Valencia City and Maramag town, Marcial Labininay, regional director of the Philippine Institute of Volcanologists (Phivolcs) told this reporter Wednesday.

Labininay said the fault study in Valencia City is needed “ASAP” (as soon as possible.) He noted that Mayor Leandro Jose Catarata has eyed a P500,000 budget to fund it.

But he said even if the new fault line is discovered in Valencia City villages recently, other LGUs in the province must already prepare to fund fault studies in their areas, especially those in areas previously identified by Phivolcs.

He added that the LGUs are the ones who usually fund the studies besides the one provided by Phivolcs, namely the geologists and the seismograph instruments. He said they are now using modern but donated seismograph instruments from Japan.

Labininay said the series of quakes in November 7, 2011 and in early September 2012 showed that aside from three confirmed fault lines traversing Bukidnon, a fourth one, identified in the meantime as “local fault line” has emerged.

He told members of the Bukidnon Sangguniang Panlalawigan Wednesday Phivolcs is zeroing in on the Lourdes-Guinuyoran area in Valencia City as observed in the latest series of quakes that jolted Bukidnon, with damages in Valencia’s two upland barangays and in several others.

He said the local fault is still unnamed and is largely blamed for the quakes in early September.

In February 2002, Phivolcs has identified four existing fault lines in Bukidnon referring to Tagoloan fault hitting portions of Malitbog and Manolo Fortich ; Cabanglasan fault, and the Central Mindanao fault, the, which hits Malaybalay City and Impasug-ong. The fourth, identified by Phivolcs in February 2012 is the Davao River fault hitting the Municipality of San Fernando.

Labininay clarified that the last fault is not within Bukidnon.

“We need a continuous study to identify the fault lines’ exact location,” Labininay told this reporter.

Renato Solidum Jr, Phivolcs director, said in a letter to the provincial board on February 2, 2012, that the new fault was not indicated in their active faults map.

“This local fault may also have been covered by recent volcanic deposits that may limit us to map this fault,” he added in his response the provincial board which passed a resolution in January 2012 requesting a geo-hazard map of Bukidnon following the November 2011 quakes.

But Solidum said their indicative maps, which became the basis for their assessments, are “not yet field-verified.”

“More detailed assessment needs to be done to validate the extent of the potential hazards,” he added.

Labininay said they have proposed a P500, 000-fault study with the City Government of Valencia “as soon as possible” to identify the exact location of the fault line. He said the study will aid the public on what possible actions to be taken in response to the discovery of the new fault line.

The Phivolcs official dismissed rumors that the 5.6 magnitude quake that jolted Bukidnon at around 3:44 a.m. on September 3 was caused by volcanic movements. He cited a total of 1,055 aftershocks as of September 19.

“It was purely tectonic in origin. It was not a volcanic earthquake,” he said, even if he confirmed that Mt. Calayo in Musuan. Maramag, Bukidnon is an “active volcano” and Mt. Kalatungan as a “potentially active volcano.”

He cited that what happened behind the tectonic quakes in Bukidnon was a seismic swarm, which is characterized by a big quake followed by small aftershocks.  In Mindanao, Burgos, Surigao del Norte and Koronadal, South Cotabato also experienced seismic swarms.

He cited that it is one of the effects of climate change.

Labininay cited the depth of focus of an earthquake is also an indicator of its danger, adding, the shallower the focus, the more destructive.  He said 30 to 50 kilometers away from the surface is “shallow” for Phivolcs.

The November 2011 quake was five kilometers down the surface, the September 2012 quakes, three kilometers, Labininay said.

He also said that Malaybalay city is less susceptible to quakes because it sits on a rocky area unlike Valencia City that sits on areas where there is observed liquefaction or soft areas.

“Even quakes in Davao City will be felt in Valencia,” he said.

Labininay said earthquakes cannot be predicted and stopped so what the public can do is boost preparedness.

He said being in the Philippines, which is in the Pacific Ring of Fire and is surrounded by active earthquake generators or fault lines, “earthquakes happen anytime.”

He cited that one aspect is the engineering of structures.

Labininay said in the remote areas like in Lourdes and Guinoyuran villages, people do not consult civil engineers in building structures.

“Even the barangay hall in the area has no building permit; most of the structures had no beams, no steel bars, or substandard mixing of cement,” he added.

He said the building official should be consulted.  (Walter I. Balane/Bukidnon News)