LEGAZPI CITY, Philippines—Mt. Mayon in Albay was jolted by 15 volcanic quakes in the past 24 hour-period on Sunday even as Mt. Bulusan in the neighboring Sorsogon province continued to show signs of restiveness.
The Philippine Institute of Volcanology and Seismology (Phivolcs) seismic network recorded 15 volcanic earthquakes and one rock fall-related event in Mt. Mayon in the past 24 hours, said a Phivolcs bulletin released on Sunday as of noon.
Moderate emission of white steam that reached a maximum height of 400 meters above the summit crater was observed drifting west-southwest and southwest, the bulletin said.
Crater glow was observed at Intensity 2 (visible to the naked eye) on Saturday night.
Results of the ground deformation measurement conducted on May 7 to 11 showed slight inflation of the volcano edifice as compared with the survey done on March 6-10, the Phivolcs said.
Alert Level 1 is still in effect over Mayon Volcano. Although this means that no eruption is imminent, the Phivolcs bulletin recommends that the public not enter the six-kilometer radius Permanent Danger Zone (PDZ) due to the continuing threat from sudden small explosions and rock falls from the upper and middle slopes of the volcano.
Active stream/river channels and those perennially identified as lahar prone areas in the southern sector of Mt. Mayor should also be avoided especially during bad weather conditions or when there is heavy and prolonged rainfall.
On the other hand, the restive Mt. Bulusan seemed to have quieted down but people should not let their guard down as its seismic signs remained unpredictable, said resident volcanologist Ed Laguerta on Sunday.
Phivolcs’ seismic instruments detected on Sunday only four volcanic quakes during a 24-hour observation period, while 11 volcanic quakes jolted the volcano on Saturday.
But the fluctuating trend in volcanic quakes still indicated that the volcano was unstable at the time, Laguerta said.
He said Phivolcs would continue to closely monitor Mt. Bulusan, particularly after it once again spewed ash on Friday and ground deformation around the volcano was seen.
He also advised local disaster councils in Sorsogon to be on alert for any event.
Volcanic ash spewed by Mt. Bulusan since it began acting up in November last year has blanketed at least 70 of villages in the towns of Juban, Irosin, Gubat, Barceloan, Casiguran and Bulusan, all areas surrounding the 1,565 meter high volcano.
The Office of Civil Defense (OCD) in Bicol, meanwhile, said Army trucks have been placed on standby in case of an eruption of Mt. Bulusan and an evacuation.
The Department of Education (DepEd) in Bicol also repeated its order to public schools to make their classrooms available as temporary shelters for evacuees.
National and local health authorities have also been assured of medicines, gas masks and health workers.
Alert Level 1 remains hoisted over Mt. Bulusan, which means that the source of activity is hydrothermal and shallow.
Residents have been warned not to enter the four-kilometer radius Permanent Danger Zone (PDZ), since the area is at risk to sudden steam and ash explosions.
Due to the prevailing wind direction, residents in the northwest and southwest sectors of the volcano are reminded to take precautions against ash falls.
Civil aviation authorities advised pilots to avoid flying close to the volcano’s summit as ejected ash and volcanic fragments from sudden explosions may be hazardous to aircraft.
Aircraft should avoid flying in the western side of the volcano as volcanic debris are likely to be carried in this direction by the prevailing winds.
Furthermore, people living near valleys, rivers and stream channels should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall.