Mayon ‘relaxing before full-blown eruption’

Rhadyz B. Barcia
Mayon ‘relaxing before full-blown eruption’
A senior volcanologist says authorities and residents should not relax despite a lull in the visible activity of Mayon the past few days. Albay Governor Salceda warns, 'If you don’t evacuate, you’re dead.'

LEGAZPI CITY, Philippines – Don’t let our guards down.

Philippine Institute of Volcanology and Seismology (Phivolcs) senior volcanologist Ed Laguerta called for caution Monday, September 22, despite a lull in the visible activity of Mayon Volcano.

“Sometimes there is a calm before the storm and there is no time to relax. Even if Mayon volcano’s restive condition appeared to be slowing down, this is just a prelude to bigger explosion,” he said.

Laguerta recalled that in 1968, 1978, 1984, and 2000, after an early increase in seismicity, there was a decrease (quiescence) in seismicity for a  few days, even weeks, before the big eruption began.

“Even the rockfall event stops – this is just a process of Mayon relaxation before a full-blown eruption, a pattern similar to 2000 to 2001 explosion with pyroclastic flow,” Phivolcs said during the Regional Disaster Risk Reduction Emergency Management Council meeting attended by NDRRMC czar Alexander Pama.

Pyroclastic flow is a turbulent mass of ejected fragmented volcanic materials, ash, and rocks mixed with hot gas that flow downslope at the velocity of 60 kph,” Laguerta said.

Laguerta said that from the May 2013 phreatic explosion of Mount Mayon that killed European hikers and a Filipino tour guide, the volcano’s unrest started where the lava dome developed and continuously grew.

The growing lava dome was captured through an aerial survey of Tactical Operations Group 5-Philippine Air Force helicopters. A protruding lava dome is now equalizing with the crater’s rim – a precursor that might cause deadly pyroclastic materials once ejected.

As the impending explosion of Mayon volcano is threatening the Albayanos, Albay Governor Joey Salceda strongly enforced the no man’s land activity in a 6-kilometer permanent danger zone (PDZ) to prevent casualties.

“If you don’t evacuate, you’re dead. So, strictly we’re enforcing the no return to 6 PDZ and extended 7 PDZ. We’re giving all your needs for you to stay away from no man’s land zone. Violation of this directive will be dealt with necessary action,” the governor said.

“We’re anticipating, that’s why we’re two steps ahead. This is the most rational [approach] because, at level 5, we will not evacuate, as even the lives of the rescuers would be at stake,” Salceda said.

At least 11,255 families or 51,963 people have been evacuated in Albay since last week after Phivolcs hoisted alert level 3. Salceda admitted that the provincial government has limited resources after the occurrence of Typhoon Glenda.

“We have limited resources so we need more resources especially after Glenda,” Salceda said.    

At most, the evacuees will be staying in various temporary shelters within 90 days which will be supported by the government’s coffer to ensure zero casualty.  

Mayon Volcano’s seismic network recorded at least 3 volcanic earthquakes and 13 rockfall events during the past 24-hour observation period with weak to moderate emission of white steam plumes drifting northeast and north-northeast was observed.

Crater glow was not observed Sunday night, while sulfur dioxide (SO2) flux was measured at an average of 1,290 tons per day. SO2 emission rates peaked at 2,360 tons per day day on September 6.

Ground deformation data showed inflationary changes in the edifice from February 2014 based on precise leveling surveys on the third week of August 2014. It showed edifice inflation from January 2012 baselines based on continuous tilt measurement.

“All the above data indicate that the volcano is exhibiting relatively high unrest due to the movement of potentially eruptible magma. This means that magma is at the crater and that hazardous eruption is possible within weeks,” Phivolcs said.

It is recommended that the 6-kilometer radius Permanent Danger Zone around the volcano and the 7-km Extended Danger Zone (EDZ) on the southeastern flank be enforced due to the danger of rock falls, landslides and sudden explosions or dome collapse that may generate hazardous volcanic flows.

Phivolcs hoisted Mayon Volcano’s alert status stands at Alert Level 3.

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