HABAGAT TRIGGERS NEW VOLCANIC THREAT: PHIVOLCS Warns of Lahar From Pinatubo and Taal—These Communities Are at Risk

MANILA, Philippines — The relentless rains brought by the southwest monsoon or Habagat have prompted state volcanologists to issue a lahar advisory for Mount Pinatubo and Taal Volcano, warning that intense and prolonged rainfall could transform volcanic sediments and ash into dangerous mudflows, muddy streamflows and runoff.

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) issued the advisory at 11 a.m. on Saturday, August 29, as heavy rainfall continued over western and central Luzon.

PHIVOLCS urged communities located in predetermined lahar and related hazard zones to remain highly vigilant and prepare for possible flooding and mudflow events.

Importantly, the advisory does not mean that Pinatubo or Taal is erupting. The immediate concern is rainfall mobilizing loose volcanic material left from previous eruptions.

PINATUBO: OLD VOLCANIC DEPOSITS COULD BE SWEPT DOWNRIVER

For Pinatubo, PHIVOLCS warned that prolonged and intense rainfall could generate lahars along major river systems draining the volcano’s western side.

Large amounts of volcanic material deposited during the 1991 Pinatubo eruption remain in the watershed. Heavy rain can remobilize these deposits, sending sediment-laden water downstream.

The agency said possible lahar activity could initially occur along the upper to middle portions of the Sto. Tomas-Marella and Bucao River systems.

The flows could then transition into muddy streamflows and flooding farther downstream, potentially affecting communities in San Marcelino, San Narciso, San Felipe and Botolan in Zambales.

PHIVOLCS also warned of possible muddy streamflows along the O’Donnell and Pasig-Potrero river systems, which could affect downstream areas in Tarlac and Pampanga.

TAAL VOLCANO: BATANGAS COMMUNITIES ALSO FACE THE RISK

The threat is not limited to Pinatubo.

Around Taal Volcano, PHIVOLCS said prolonged and heavy rainfall could generate muddy streamflows and runoff along areas west of Taal Lake.

Thin remnants of volcanic ash in these areas can be remobilized by intense rainfall, potentially producing muddy flows that could affect Agoncillo and Laurel in Batangas.

PHIVOLCS advised local government units and residents in potentially affected areas to closely monitor weather conditions and implement precautionary measures when necessary.

PAGASA: RAINFALL COULD BE HEAVIER IN MOUNTAINOUS AREAS

The warning comes as the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) continues to monitor the effects of the southwest monsoon.

In its Saturday weather advisory, PAGASA warned of moderate to intense rainfall over western and central Luzon. Rainfall could be heavier over mountainous and elevated areas, while previously accumulated rainfall could further worsen flooding and other rain-related hazards.

GMA News also reported that PAGASA had issued red and orange rainfall warnings over several areas in Central Luzon and Calabarzon at the time of the PHIVOLCS advisory.

NO NEW ERUPTION WARNING—BUT THE RAINFALL HAZARD IS REAL

The distinction is important.

PTV News reported that Taal Volcano remains under Alert Level 1, indicating low-level volcanic unrest, while Pinatubo remains at Alert Level 0, or normal status. The current PHIVOLCS advisory concerns rainfall-triggered lahars and muddy runoff rather than a new volcanic eruption.

However, authorities are urging residents not to underestimate the danger.

Lahars can behave like fast-moving flows of water, mud, rocks and volcanic debris, particularly when large amounts of loose volcanic material are suddenly mobilized by intense rainfall.

For communities downstream of volcanoes and river channels, the danger may therefore come not from the volcano erupting, but from what heavy rain can suddenly move down its slopes and waterways.

COMMUNITIES URGED TO PREPARE

PHIVOLCS is calling on affected local governments and communities to remain alert, monitor changing weather conditions and take preemptive response measures when needed.

Residents near river channels and other predetermined hazard zones should pay particular attention to official advisories, especially during periods of prolonged or intense rainfall.

With the Habagat continuing to dump heavy rain across parts of Luzon, authorities are keeping a close watch on both volcanoes and the waterways that drain them.

For now, the message from PHIVOLCS is clear: Pinatubo and Taal are not being placed under a new eruption alert because of this advisory—but heavy rain could still unleash dangerous volcanic mudflows downstream.