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Eruption at Mayon Volcano, Luzon Island, Philippines

19 Jan 2018

A lava dome and degassing at the Mayon Volcano summit crater (Source: Philippine Institute of Volcanology and Seismology)

Mayon Volcano is currently erupting.

Mayon, on Luzon Island in the Philippines, entered a new eruptive phase on 13 January 2018, according to the Philippine Institute of Volcanology and Seismology (PHIVOLCS), Philippines’ Geological Agency. This phase included steam-driven eruptions and flows from a new lava dome growing at the summit of the volcano.

PHIVOLCS is closely monitoring the evolution of the eruption, and putting exclusion zones in place. On 14 January 2018, PHIVOLCS raised the alert level from 1 (abnormal) to 2 (increasing unrest), and then to 3 (increased tendency towards hazardous eruption).

The current exclusion zones include a Permanent Danger Zone (PDZ) that extends in a 6-kilometre (km) radius around the volcano, and an Extended Danger Zone (EDZ) that extends 7 km on the southern flanks of the volcano, due to higher hazard in this area.

The current unrest of Mayon is being closely monitored by PHIVOLCS using a range of techniques (seismicity, deformation, gas emissions and visual observations). Regular updates about Mayon’s activity are posted on the PHIVOLCS website.

Summary of Recent Activity

The new eruptive phase at Mayon started on 13 January 2018, with a steam-driven eruption sending a greyish plume 2,500 metres (m) into the air. This eruption was not preceded by any immediate sign of precursory activity, but by a slight inflation of the volcano since October 2017.

The eruption prompted PHIVOLCS to raise the volcanic alert level from 1 to 2. Numerous rockfalls and two other steam-driven eruptions subsequently occurred, and crater glow was observed indicating the growth of a lava dome.

On 14 January, lava flows started to be observed on the southern slopes of the volcano and the volcanic alert level was raised to 3. On 15 January, two lava collapse events (producing rockfalls and pyroclastic density currents) and degassing events sent ash plumes towards the southwest and west-southwest sectors of the volcano.

An ash cloud from the advancing lava flow on the Miisi Gully and degassing at Mayon summit crater (Source: Philippine Institute of Volcanology and Seismology)

The most recent activity includes lava flows and collapse events from the new dome. Sulfur dioxide gas emission was measured at an average of 3,293 tonnes per day on 16 January. More details can be found in volcano bulletins released by PHIVOLCS.

Background and Challenges

Mayon is a stratovolcano, a volcano made up of many layers of lava and ash. It is the most active volcano in the Philippines, and is located just 2,559 km northeast of  Singapore. Its summit reaches 2,463 m above sea level.

Mayon has had many past eruptions, with an average repose of 10 years between eruptions. Generally, effusive eruptions precede weak to moderate explosive eruptions of tephras, lava flows and pyroclastic flows (mostly strombolian eruptions). The last eruption occurred in August 2014 and was characterised by the growth of a lava dome.

PHIVOLCS has published several hazard maps which, in the event of an eruption, outline the areas that may be impacted by hazards such as pyroclastic flows, lava flows, lahars, and ashfall. The maps show the location of the Permanent Exclusion Zone, 6 km from the volcano’s vent, and the Extended Exclusion zone, 7 km from the vent on the southern flank of the volcano.

It is challenging to forecast Mayon’s activity because the volcano is an open system. It is continuously degassing (releasing about 500 tonnes of Sulphur Dioxide emissions per day), which prevents pressure from  building up within the volcano. This makes it difficult to observe seismicity and deformation before an eruption.

Collaborations Between EOS and PHIVOLCS

PHIVOLCS is the institute responsible for volcanic, seismic, and landslide risk mitigation in the Philippines. It develops policies, norms, and procedures related to geological hazards in the country. It also conducts independent research on volcanoes in the Philippines, and provides advice to communities near active volcanoes regarding engineering and urban planning.

In March 2017, PHIVOLCS and EOS conducted a collaborative study to identify the composition of Mayon Volcano's plume (Source: Charlotte Barrington)

The Volcano Group at the Earth Observatory of Singapore (EOS) In collaboration with PHIVOLCS are studying Mayon in Southeast Luzon, Philippines using a multi-parametric approach, involving measurements of seismicity, deformation, and gas. The goals are to recognise and properly interpret magmatic ascent as soon as possible. We would like to address questions such as:

•       What is the volcano doing during repose?

•       How is magma transported from the reservoir to the surface?

•       How to interpret signals during an eruption?

This work is complemented by a range of other geological, petrological and geochemical studies that will be combined to provide a comprehensive understanding of the volcano. Ultimately, we hope to be able to incorporate this information into forecasting algorithms and give probabilistic estimates of eruptions.