By REY M. NASOL
LEGAZPI CITY — Government scientists issued warnings on the risk of flashfloods and landslides in areas near Mayon Volcano as the tail-end of the cold front continued to dump heavy rains across Albay province Thursday.
“The weather situation indicates that more rains would take place over areas around the volcano and these may cause water-triggered disasters, particularly in low-lying sites,” Alex Baloloy, science research analyst of the Philippine Institute of Volcanology and Seismology (Phivolcs) said in an advisory aired over local radio stations here recently.
Heavy rains, from intermittent to continuous, have been pelting the southeastern and central sections of the province since early this month and, although the Philippine weather bureau allayed fears of a typhoon before the end of the year, Baloloy said the situation calls for the activation of local disaster risk reduction management councils.
He said water level in all river channels emanating from the slopes of the volcano and stretching down beyond the danger zones are already high and may overflow anytime, given the huge volume of rainwater still expected to be dumped the whole day by the prevailing weather condition.
Residents near river banks should be vigilant and be ready to evacuate anytime, Baloloy said.
Baloloy added that Mayon is under alert level 1, which is abnormal and has exhibited three high frequency volcanic quakes during the past 24 –hour observation period.
In Mt. Bulusan in Sorsogon province, barely 80-kms away from Mayon, moderate lahar flow has been taking place over rivers channels along the slopes, resident volcanologist Eduardo Laguerta said, adding that landslide-prone areas at the Casiguran and Juban towns sections of the volcano should stay watchful and, better still, evacuate to safer grounds.
On the abnormal condition of the volcano, Laguerta said that, although it has been silent for the past two weeks, alert level number 1 remains in effect, which means the danger of eruptions still exists giving reasons for a ban of human activities within its four-kilometer permanent danger zone (PDZ).
The Phivolcs seismographs at its Mt. Bulusan Observatory in Barangay Cabid-an here, he said, have been detecting only moderate tremors around the volcano, indicating no significant volcanic movement during latest monitoring periods.
“The important thing is to observe the PDZ. Even if there is no apparent volcanic activity, sometimes, steam-driven explosions can occur and this is what people should look out for,” he added, explaining that steam-driven explosions are due to hot rocks under the volcano interacting with rainwater.
The same activity took place as Bulusan restarted acting up in the morning of November 6, sending an ash column some 600 meters from the crater, Laguerta said.
Several other similar types of explosions, characterized by massive ejection of ash and steam, followed early this month. All those eruptions were categorized as phreatic for the absence of magmatic or lava intrusion.
Those eruptions, the resident volcanologist said, are considered preparatory to major eruptions “that is why we are not letting our guard down.”