PHIVOLCS issues lahar advisory for Pinatubo, Taal as Habagat rains pour

State volcanogists warned Saturday that the heavy rains brought by the southwest monsoon or Habagat may trigger volcanic mudflows or debris flows, known locally as lahar, in Pinatubo and Taal volcanoes.

In an 11 a.m. advisory, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) cited the impact of the expected Habagat-induced heavy rainfall over the western and central areas of Luzon.

"This could generate volcanic sediment flows or lahars, muddy streamflows or muddy run-off in rivers and drainage areas on Pinatubo and Taal volcanos," PHIVOLCS said.

With this, PHIVOLCS said it "strongly recommends increased vigilance and readiness of communities in pre-determined zones of lahar and related hazards on these volcanoes."

The weather bureau issued red and orange rainfall warnings at 11 a.m. covering multiple areas in Central Luzon and Calabarzon where Pinatubo and Taal are located, respectively.

LAHAR ADVISORY

.@phivolcs_dost, naglabas ng lahar advisory sa Bulkang Pinatubo at Bulkang Taal, sa gitna ng patuloy na pag-ulan. pic.twitter.com/bUHwuh4LOb

— DZBB Super Radyo (@dzbb) August 29, 2026

PHIVOLCS said prolonged and intense rainfall may generate lahar on major rivers draining the western section of Pinatubo, where "significant deposits" of Pinatubo's violent eruption in 1991 still remain.

The 1991 incident at Pinatubo is the world's second-largest eruption of the 20th century, which left 847 dead, 184 injured, and 23 missing, according to park.org, a website devoted to Pinatubo.

Phivolcs said lahar may occur on the upper to middle reaches of the Sto. Tomas-Marella and Bucao River systems. It may transition to muddy streamflows and floods on the lower reaches and affect communities in San Marcelino, San Narciso, San Felipe, and Botolan in Zambalaes.

Muddy streamflows may also be generated along the O'Donnell and Pasig-Potrero River systems draining Pinatubo to the north and southeast. Should this happen, downstream communities in Tarlac and Pampanga may be affected, PHIVOLCS said.

As for Taal Volcano, PHIVOLCS said muddy streamflow and muddy runoff may happen on the slopes west of Taal Lake, where "thin remnant ash can be remobilized." Such incidents may recur, the agency said, in Agoncillo and Laurel towns in Batangas.

PHIVOLCS advised local government units and communities in these areas to monitor weather conditions and "take preemptive response measures" for the residents' safety. — VDV, GMA News