By Celso Amo
MANILA --- The provincial government of Albay has declared a “state of calamity” Tuesday, January 16, following eruptions by Mayon Volcano.
In an interview over national TV, Albay Gov. Al Francis Bichara asked the assistance of various government agencies and the private sector to help ease the plight of affected residents and evacuees.
Mina Marasigan, National Disaster Risk and Reduction Management Council spokesperson, said that a total of 5,318 families or 21,823 persons were forced to leave their residences as of Monday night (Jan. 15) due to a “lava fountain” from Mayon Volcano.
The Philippine Institute of Volcanology and Seismology
raised the alert status of Mayon Volcano to Level 3 Sunday night after exhibiting “relatively high unrest and that magma is at the center.”
Last Saturday, Mayon Volcano, the country’s most active volcano, generated a steam-driven explosion.
Mayon has been silent since October 2014 after a silent eruption and the formation of a lava dome as it ran out of magmatic gas to propel a major eruption.
The tail-end of the cold front is making observation as well as the conduct of sulfur gas emission around the volcano difficult.
Under Level 3, the 2,462-meter high volcano is on a relatively high level of unrest as new magma continues to rise to the summit dislodging old deposits which triggered lava collapse and huge boulders to roll down the slope causing pyroclatic flows.
Residents from nearby towns of Daraga, Camalig, Guinobatan, Malilipot, and Ligao City were forced to leave their residences following last Monday’s phreatic explosions and lava flow.
Renato Solidum, Phivolcs director, said on Tuesday morning that lava continues to flow and more lava collapse have been observed during the past 24 hours monitoring period.
Ten lava collapse incidents were recorded Tuesday morning, Solidum said.
“Lava is coming out as well as the collapse of the lava’s side at the summit resulting in small pyroclastic flows and producing eruption ash clouds like advancing columns not due to summit eruption but to continuing lava downward flow,” he said.
Lava flows are streams of molten rocks that originate from a volcanic vent.
Lava collapse happens when large volcanic boulders roll down and generate pyroclastic flow or pyroclastic density current.
Solidum also said that four events of lava fountaining were observed at Mayon volcano Monday evening which were captured by Phivolcs monitoring cameras.
“The lava fountaining was accompanied by tremors which didn’t last long compared to previous eruptions whose duration was longer,” Solidum said.
Asked if indicators show Mayon is moving towards a major eruption, Solidum said all the indicators point to an eventual eruption but not enough yet to raise the Alert Level 3 to 4.
Alert Level 3
Alert Level 3 remains in effect over Mayon Volcano, which means that it is currently in a relatively high level of unrest as magma is at the crater and hazardous eruption is possible within weeks or even days.
Solidum said lava flow which was concentrated at the Miisi Channel has now branched off from the summit towards Bonga Channel.
“It’s moving towards Buyuan due to a lower elevation.”
The Phivolcs scientist said lava travels faster because it was less viscous, or sticky or semifluid.
He said lava started to flow at Mayon starting Saturday after the phreatic eruption unlike in previous eruptions when it took some years before lava started to flow.
“Fast and less viscuous lava is moving at two kilometers at 1.2 elevation,” said Solidum.
Ed Laguerta, Mayon resident volcanologist, said two lava collapse events were observed 1:30 p.m. on Monday that produced rock fall and small-volume pyroclastic density currents.
Lava collapse first occurred at 9:41 a.m. and at 10:05 a.m. that lasted five minutes and seven minutes, respectively, based on seismic record.
Laguerta said the events appear to have originated from the lava front and produced an ash cloud that drifted to the southwest sector.
Ashfall were reported in Barangays Travesia, Muladbucad Grande, Maninila, Masarawag, Poblacion, Iraya, Ilawod, Calzada, Inamnan Grande, Inamnan Pequeno, Maguiron, Quitago and Mauraro in the municipality of Guinobatan; and Barangays Cabangan, Anoling, Sua, Tumpa, Quirangay, Gapo, Sumlang, Brgys. 1 to 7, in the municipality of Camalig.
A degassing event was observed at 11:07 a.m. that lasted eight minutes and produced a grayish to dirty white ash column with a maximum of height of approximately 1000 meters above the summit before drifting west-southwest.
Mayon Volcano for the past 24 hours has noticeably increased its unrest.
The crater summit brightened and lava flowed towards Barangay Miisi and Bonga Gully.
“The pulverized parts of the hot lava dome and fragments of the lava flow generated a pyroclastic flow,” informed Laguerta during an emergency meeting held at Albay Provincial Security and Emergency Management Office (APSEMO) Monday afternoon.
He said the present alert status of Mayon at three has not been raised because the source of unrest is not internal but external from the collapsed portion of the dome.
He said the pyroclastic flow generated ash column that moved towards the direction of Guinobatan town.
Areas at risk from the pyroclastic flow is the south-west quadrant of the volcano.
Laguerta said the lava dome has now become unstable due to the pressure of the new magma moving up from underneath the crater.
“When the weather improves we will find out the exact direction of the pyroclastic flow,” said Laguerta.
A lava dome came out during Mayon’s silent eruption on September 2014.
“There’s a need to determine the amount of sulfur gas output and inflation so we will know the direction of Mayon’s present unrest,” said Laguerta.
Bad weather has hindered them from conducting assessment of the sulfur gas output
Laguerta said after three phreatic eruptions and 158 rock fall events between 4:21 p.m. on January 13 and 7:25 p.m. on January 14, Mayon’s summit crater is now exhibiting bright crater glow that signifies the growth of a new lava dome and beginnings of lava flow towards the southern slopes.
Situation in Legazpi City
Meanwhile, Legazpi City Mayor Noel Rosal has ordered the city disaster risk reduction and management office to prepare the evacuation of some 3,000 or 15,000 villagers from Barangays Mabinit, Buyuan, Matanag, Bonga and Padang located at the southwest of Mayon volcano facing the lava dome.
These barangays are located inside the 8-kilometer extended danger zone.
The mayor also ordered suspended any form of activity inside the extended 8-kilometer danger zone at the southeast quadrant such as farming, orchids gathering, golf games, and hiking.
Rosal had an emergency meeting with the barangays chairmen of the five affected barangays and disaster officials.
He said the city is facing multiple risk from Mayon unrest as well as the tail-end of the cold front which triggers heavy rains and lahar in the barangays along the slope of the volcano.
He ordered round-the-clock dredging of major river channels which are heavily silted in Barangay Peñaranda, Oro Site, and Bitano which prevents flood waters from moving towards the pumping stations at Barangay San Roque, Victory Villager, and Dap-Dap which is the outflow of Makabalo River.
“We will order a mandatory evacuation when Mayon Alert Level is raised to 4,” said Rosal.
The barangays mentioned are highly at risk because they are facing the lava dome, a remnant of Mayon Volcano’s effusive eruption on September 2014.
Rosal also is closely monitoring the rainfall level due to the intermittent rains spawned by the tail-end of the cold front.
Rosal also said he a amenable to hire a security guard to watch Phivolcs monitoring network in Barangay Padang.
The public is strongly advised to be vigilant and desist from entering the six (6) kilometer-radius Permanent Danger Zone (PDZ) and the 7-km Extended Danger Zone (EDZ) on the southern flanks due to the danger of rockfalls, landslides and sudden explosions or dome collapse that may generate hazardous volcanic flows.
Civil aviation authorities have also advised pilots to avoid flying close to the volcano’s summit as ash from any sudden eruption can be hazardous to the aircraft and its passengers. Based on the seasonal wind pattern, ash fall events may most likely occur on the southwest side of the volcano.