Phivolcs: ‘Ulysses’ may trigger lahar flows near Mayon, Taal and Pinatubo volcanoes
MANILA, Philippines — The Philippine Institute of Volcanology and Seismology warned Wednesday that prolonged and intense rainfall brought by Typhoon Ulysses could cause lahar flows in communities near Mayon, Taal and Pinatubo volcanoes.
"Ulysses" (international name: Vamco) intensified into a typhoon ahead of its landfall Wednesday evening. It is expected to bring “destructive winds and intense with at times torrential rainfall” as it makes its way across Luzon.
In an advisory, Phivolcs warned that the typhoon’s intense rains may wash away deposits of pyroclastic materials left from the Pinatubo Volcano’s eruption in 1991.
Pinatubo lahars are expected to be “channel-confined” and occur on the upper to middle reaches of the Sto. Tomas-Marella and Bucao river systems. But these may also transition to muddy stream flows and floods on the lower reaches and affect adjacent communities of San Marcelino, San Narciso, San Felipe and Botolan in Zambales province.
Muddy stream flows may be also generated along the O’Donnell and Pasig-Potrero river systems draining the volcano edifice to the north and southeast and affect downstream communities in the provinces of Tarlac and Pampanga.
Rains brought by "Ulysses" may also trigger muddy stream flow and muddy runoff around Taal Volcano, which erupted in January this year, particularly on the slopes west of Taal Lake where thin remnant ash can be remobilized in streams and roads, and overland of the lakeward slopes.
“In particular, muddy streamflow and runoff can recur on previously affected communities of Agoncillo and Laurel [in] Batangas province,” Phivolcs said.
In an advisory issued Tuesday afternoon, the state seismologists warned that pyroclastic density current deposits from the 2018 eruption may be washed away by heavy rainfall.
Phivolcs said Mayon lahars can threaten communities along the middle and lower slopes and downstreams of channels draining the volcano’s edifice with “inundation, burial and wash away.”
Phivolcs chief Renato Solidum advised communities to monitor the storm conditions and take pre-emptive measures.
“Residents of these areas should be careful and local governments must take action to ensure their safety,” Phivolcs chief Renato Solidum said in a briefing.
The torrential rains of Super Typhoon Rolly, during the height of its rampage, washed away debris and boulders from Mayon Volcano and buried at least 300 houses in Guinobatan, Albay.
The Department of Environment and Natural Resources is investigating the lahar probe incident and has suspended quarrying operations around the volcano.
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