LEGAZPI CITY, Philippines – With rains pouring over Albay in Bicol for the past few weeks, local government officials are preparing for the possibility of a Mayon eruption coinciding with or being followed by a storm or typhoon.

“We will expand our evacuation to up to 110,000 people because we will include populations very close to the river channels and the sea,” said Albay Public Safety and Emergency Management Head Cedric Daep on Monday, October 6.

People living near river systems are at great risk from flood-driven lahar which usually find their way to river channels which are also old lahar paths. The expected hazardous eruption, due in weeks, could happen during the typhoon months of October or November. (READ: Albay needs P118M a month for Mayon evacuation)

Such a combination can greatly increase casualties and damage such as what happened in the 2006 Mayon eruption followed by Typhoon Reming (international name Durian) 4 months later. 

Reming drove the just-expelled volcanic ash in the sides of the volcano down to the villages living at its feet. The deadly floods and lahar combination killed around 1,200 people and wrought P1.13 billion (US$2.5 million) worth of damage to agriculture, aquaculture and infrastructure. 

To prevent a similar disaster, the provincial government of Albay plans to relocate communities living near major waterways and the sea aside from the population who live in the 6 kilometer danger zone already in evacuation centers.

The evacuation will be green-lighted once rainfall reaches beyond 6 millimeters per hour, which Daep says is the cue for lahar on the sides of the volcano to be driven down.

This standard will apply regardless of the type of weather system pouring over the province, he added.

The deadly lahar of 2006 was triggered by a record-high amount of 466 millimeters of rainfall in 12 hours.

According to the Philippine Institute of Volcanology and Seismology (Phivolcs), the water-driven lahar flow began only around 10 minutes after the onset of Reming’s floods at 2 pm on November 30, 2006.

The swift-moving lahar and flood waters caused giant volcanic boulders to roll down its steep slopes. The lahar buried entire villages before making their way out to sea.

Can’t lower alert level yet

While no volcanic quakes or significant number of rockfalls were detected in the past few days, Mayon remains at Alert Level 3 which means it is due for an eruption in weeks, said Phivolcs resident volcanologist Ed Laguerta.

Though the volcano appears to be quiet, Phivolcs has observed a reverse pattern in the amount of gas released from the crater and the inflammation of the lower part of the volcano.

“If magma is rising, it should be that the value of gas [released] is at least maintained. But what we’re seeing is while it is inflating and the volume of rising magma is increasing, the gas value is going down,” he told media.

Last September 30, the amount of gas released was 1,251 tons average. On October 2, it went down to 308. On Sunday, October 5, it decreased further to 148.

This means that gas from new magma rising to higher chambers isn’t being released and is instead building up pressure inside the volcano, he explained. The higher the pressure inside the volcano, the more destructive the expected eruption may become.

“That’s why even if it’s quiet looking, we cannot lower the alert level,” he said.

Phivolcs and the Albay provincial government are looking at 3 scenarios if the hazardous eruption is a vulcanian one – the most destructive type of eruption that could cause hot volcanic ash, debris and lahar to fall down the slopes at speeds of up to 500 kilometers per hour.

One scenario is for the eruption to cause the collapse of the lava dome spotted since August 15. The lava dome could cause more debris to fall towards the southeastern quadrant of the province which includes Legazpi City and the towns of Daraga and Santo Domingo.

In the second scenario, only the north wall of the crater will collapse because the eruption was not strong enough to collapse the lava dome. This would put northern communities at the greatest risk, communities like Tabaco City and the towns of Malilipot and San Vicente.

The 3rd and worst case scenario, according to Daep, is if the eruption creates an ash column. This would mean the deadly debris will be expelled outwards towards all communities surrounding Mayon.

Daep gave assurances that the preparations they are currently making are for the 3rd scenario.

Keeping evacuees where it’s safe

In the meantime, the Albay government, along with the Office of Civil Defense (OCD) Region 5, are working on ways to keep evacuees in the evacuation centers.

The biggest challenge to Albay’s zero casualty campaign is the tendency of evacuees to go back to the 6 kilometer danger zone to tend to their crops and animals, guard their property from thieves, take a bath and wash their clothes.

This week, the local government plans to cut electricity and water lines from houses inside the danger zone as a last ditch effort to stop evacuees from returning, said OCD Region 5 Director Raffy Alejandro.

They are also aiming to increase the number of work animals relocated to grazing fields outside the danger zone so that evacuees can go their instead.

A cash-for-work or food-for-work program is also in the works with the Department of Social Welfare and Development to provide temporary alternative form of income for the farmer evacuees, said Alejandro. 

But the biggest source of discomfort in evacuation centers is still the lack of water and comfort rooms. 

According to 35-year-old evacuee Veronica Rosana, people in evacuation centers are forced to line up as early as 3 am in front of water faucets and wait for as much as two hours for their turn.

“That’s why some people just decide to return to their houses in the danger zone so they can wash their clothes or take a bath properly.”

Daep said the provincial government “is doing everything they can to address the situation.” – Rappler.com