Bulusan Volcano erupts anew; Alert Level 1 remains —PHIVOLCS

Bulusan Volcano in Sorsogon had another phreatic eruption before dawn on Sunday, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) said.

The phreatic eruption occurred at 3:37 a.m. and lasted for 18 minutes, it added.

A plume rose up from the crater, PHIVOLCS Director and Science Undersecretary Renato Solidum Jr. said in an interview on Super Radyo dzBB.

"Alert Level 1 ay maintained," he added.

According to PHIVOLCS, a phreatic eruption refers to a steam-driven explosion that occurs when water beneath the ground or on the surface is directly heated by hot rocks or new volcanic deposits (e.g. pyroclastic density currents, lava) or indirectly by magma or magmatic gas.

In its volcano bulletin, PHIVOLCS said 136 volcanic earthquakes were reported in Bulusan Volcano in the past 24 hours.

The volcano also emitted 613 tonnes of sulfur dioxide on June 10.

A 150-meter tall plume emitted by the volcano drifted west-northwest and northwest.

Ashfall

Solidum said ashfall was reported in parts of the municipality of Juban. 

Juban, Sorsogon Municipal Disaster Risk Reduction Management Office (MDRRMO) Public Information Officer Arian Aguallo later said the whole municipality of Juban was affected by ashfall.

“Medyo scattered po ngayon ang bagsak ng ashfall, hindi lang concentrated sa isang barangay. As of now, buong munisipyo po may traces of ashfall. Pero may mga selected barangays na heavily affected,” he said.

(The ashfall is now quite scattered and is not just concentrated in one barangay. As of now, the entire municipality has traces of ashfall but some selected barangays are heavily affected.)

Aguallo, however, assured that there were no adverse events reported so far, and residents have not yet been advised by the local government to evacuate their homes.

At past 9 a.m., however, the National Disaster Risk Reduction and Management Council (NDRRMC) said evacuation of residents has started in some barangays in Juban.

"Ongoing din po ang evacuation sa oras na ito. May natanggap po kaming report na 103 families/438 pax ang bilang na nag-evacuate mula sa Juban," the NDRRMC told reporters.

(The evacuation [of residents] is ongoing as of the moment. We have received a report that 103 families or 438 individuals have been evacuated from Juban.)

"Ongoing po ang aming coordination with the regional counterpart. As of this moment ay we received a report na may ashfall incident sa Casiguran, Juban, Irosin," it added.

(We have an ongoing coordination with the regional counterpart. As of this moment, we received a report of ashfall incidents in Casiguran, Juban, Irosin.)

Sorsogon Governor and incoming Senator Francis "Chiz" Escudero earlier said nine barangays in the municipalities of Juban, Casiguran, and Magallanes had ashfall.

Pattern

Solidum said Bulusan Volcano's eruptions this month are consistent with its pattern before of having phreatic eruptions and low-level volcanic earthquakes.

"Sa kasalukuyan, ang ipinapakita ng Bulkang Bulusan ay kapareho na ng mga ipinakita nitong eruption episodes nitong mga nakaraang taon o dekada... Mga phreatic eruption ang nakikita natin, maliliit ang lindol," he said.

(Currently, what Bulusan Volcano is showing is the same as its eruption episodes in the past year or decade... These are phreatic eruptions with low-level volcanic earthquakes.)

"Hindi natin inaalis na puwedeng sumali ang magma sa kanyang aktibidad na more than 200 years ago nangyari," Solidum added.

(However we are not discounting the possibility that magma may be involved in the volcano's activity which last occurred more than 200 years ago.)

Solidum said PHIVOLCS issued an advisory earlier this week about the volcano's increased activity, notably volcanic earthquakes.

"Noong isang gabi, nagpalabas kami ng advisory dahil muling dumami ang volcanic earthquakes sa Bulusan at sinabi nating maaari itong sumabog sa loob ng ilang oras o araw... Since then, mahigit 100 volcanic earthquakes ang ating naitala pero hindi naman malalakas," he said.

(The other night, we issued an advisory because the volcanic earthquakes increased. And we said this may lead to an eruption in hours or days. Since then, more than 100 volcanic earthquakes have been recorded but these were not strong.)

"Hindi pa rin natin masasabing tapos na. At posible pang masundan ang pagsabog kaya kailangang bantayan ang Bulkang Bulusan," Solidum added.

(We cannot say the eruption [this morning] is the end of it. It may possibly be followed by another eruption so we have to monitor Bulusan Volcano.)

For now however, PHIVOLCS could not yet see the parameters needed to escalate the alert level to 2, he said.

"Wala tayong nakikitang parametro na may magma na umaakyat ng bulkan... Ang magmatic eruption ay mas delikado. Doon tayo nakaumang (kung itataas sa Alert Level 2)," Solidum said.

(We don't see the parameters being met yet, such as magma going up the volcano. A magmatic eruption is more dangerous. We will raise Alert Level 2 if there is magmatic activity.)

The PHIVOLCS official said Bulusan Volcano may have pyroclastic flow when eruption is more intense.

"Hindi lang abo ang deposito ng Bulkang Bulusan... Mayroong pyroclastic flow, 'yung mga abo at bato... gumugulong 'yan ng mabilis... Ito ang iniiwasan natin kaya bago magkaroon ng malakas na pagsabog ay naglilikas na tayo," Solidum said.

(Aside from ash, Bulusan Volcano also has pyroclastic flow with rocks. This would roll out fast. We are avoiding this so evacuation is necessary if we are expecting a strong eruption.)

"Base sa mga deposito, may mga mas delikadong eruption ang Bulusan... Sa ngayon, mga phreatic eruption ang ating nakikita... Dahil maliliit pa ang lindol, 'yung pressure kung mayroon man ay sa ibabaw lang," he assured.

(Based on deposits, Bulusan Volcano has had more dangerous eruptions [in the past]. For now, we only see phreatic eruptions. Because the volcanic earthquakes are low-level, the pressure, if there is any, is only near the top.)

PDZ

PHIVOLCS reminded the public and local government units that entry is not allowed into the 4-kilometer radius Permanent Danger Zone (PDZ).

Likewise, vigilance must be exercised in the 2-kilometer Extended Danger Zone on the southeast sector, it said.

PHIVOLCS said flying close to the volcano's summit is hazardous since ash can damage aircraft.

Airport authorities thus announced the cancellation of some flights for Sunday, June 12, 2022, due to Bulusan Volcano's unrest. 

"Furthermore, people living within valleys and along river/stream channels especially on the southeast, southwest and northwest sector of the edifice should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall should phreatic eruption occur," it added.

Solidum also advised motorists to take extra caution as roads may be slippery due to ashfall.

Sunday's eruption occurred a week after Bulusan Volcano's phreatic eruption on June 5 at 10:37 a.m.

PHIVOLCS then raised the alert level from zero (normal) to Alert Level 1 (low-level unrest). —KG, GMA News