I. Situation Overview
On 05 June 2022, at 10:37 AM, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) has raised the alert status of Bulusan Volcano from Alert Level 0 (Normal) to Alert Level 1 (Low-level Unrest) after a phreatic eruption occurred at the volcano’s summit that lasted approximately 17 minutes which was recorded by seismic and infrasound monitoring by the Bulusan Volcano Network (BVN). The event was poorly visible through cloud cover over the edifice although a steam-rich grey plume at least one kilometer tall was observed from Juban, Sorsogon and was subsequently observed to drift west.
The eruption produced a sluggish gray ash plume that rose more than a kilometer and dispersed wet ash to the west coincident with rainfall over the edifice. Thin fine ashfall fell on the general northwestern sector of the edifice and affected the barangays of Puting Sapa, Añog, Guruyan, Catanusan, Buraburan, Bacolod, and Sangkayon in Juban and Bolos in Irosin, Sorsogon Province. Rumbling sound and sulfurous odor were also observed by residents of Brgys. Añog, Guruyan, and Catanusan. After the eruption, degassing was observed from the crater and, for the first time this year, from the northwest summit vent.
On 10 June 2022 at 8 PM, residents of ashfall-affected barangays in Juban, Sorsogon, are ordered to be evacuated due to the observance of the increased seismic activity of Bulusan Volcano.
On 12 June 2022 at 3:37 PM, an eruption was detected by the BVN. The eruption lasted for approximately 18 minutes and was recorded as an explosion type earthquake by seismic and infrasound instruments, but could not be visually observed in the dark of night. The explosion was felt at Intensity III by residents of Brgy. Añog, Juban and at Intensity II in Brgy. Inlagadian, Casiguran, all within 5-km of the Bulusan summit. Rumbling sounds accompanying the eruption were also reported by witnesses in Sitio Bagong Barrio, Brgy. Santa Lourdes, Barcelona, Brgy. Inlagadian and Brgy. San Juan, Casiguran, Brgy. Bentuco, Gubat, and Brgys. Añog, Calateo, and Puting Sapa, Juban. A brief incandescence at the base of the eruption plume was also reported in Brgy. Inlagadian, Casiguran. By daybreak, multiple active vents at the summit could be observed spewing ash and steam to a height of at least 500 m before being drifted to the northwest. In the morning, six vents – the major crater called Blackbird, three explosion pits on the summit, and the lateral vents on the northwest and north sides of the summit – were actively degassing short plumes which entrained ash until at least 9:00 in the morning. The plumes dispersed into a long veil of ash extending several kilometers to the northwest. This period of “ashing” was accompanied by very weak sporadic volcanic tremor. Degassing of steam-laden plumes continues while the Blackbird Crater generates a thin haze of ash upon the upper northwestern slopes.
The fine ashfall can cause irritation and breathing problems especially among the vulnerable population – the elderly, children, expecting mothers and those with respiratory disorders – and can be particularly dangerous when inhaled in copious amounts. In addition, ashfall even when thin but having high amounts of sulfur can also cause irritation.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
II. Status of Affected Areas and Population
There are 10,707 families or 44,669 persons affected by the Bulusan Volcano eruption in 30 barangays in Region V (see Table 1).