MAYON VOLCANO BULLETIN

05 March 2024

05:30 PM

 

This serves as notice for the lowering of the alert status of Mayon Volcano from Alert Level 2 (Moderate Level of Unrest) to Alert Level 1 (Low Level of Unrest).

 

Since the start of the year, Mayon Volcano has exhibited a steady decline in its monitored parameters. This is supported by the following observations:

 

1. Volcanic Earthquake Activity: Volcanic earthquakes recorded by the Mayon Volcano Network (MVN) have declined to a daily average of 2-3 earthquakes/day since the first week of January 2024. A considerable number of these earthquakes are related to rock fracturing processes within the volcano. In addition, rockfall from Mayon’s summit dome averaged 0-1 events/day indicating a significant slowing down of lava dome growth.

 

2. Ground Deformation: Long-term ground deformation data from Global Positioning Systems (GPS), Electronic Distance Measurements (EDM) and electronic tiltmeters show that the edifice is still inflated overall. Short-term data indicate deflation of the general northern middle slopes, whereas recent inflation of the general southern slopes and continued inflation of the upper slopes is occurring. Microgravity observations likewise show positive (density increase) and negative (density decrease) microgravity anomalies on the northern lower and middle slopes of the volcano, respectively. Ground deformation and microgravity anomalies are interpreted to be caused by crystallization of the resting magma beneath the volcano. 

 

3. Volcanic Gas Emission: Sulfur Dioxide emission or SO2 flux from Mayon crater based on continuous gas spectrometry has varied between a high 2,394 tonnes/day on 22 January 2024 to a low of 420 tonnes/day on 5 March 2024. Since January 2024 to present, the SO2 flux has averaged 1148 tonnes/day. Overall, SO2 emissions are above the background level of 500 tonnes/day, consistent with continued degassing from the resting un-erupted magma.

 

4. Visual Observation of the Summit and Lava Flow: Mayon’s summit crater has generated only weak to moderate degassing plumes this year. Since 8 December 2023 when the status of Mayon was lowered to Alert Level 2, crater glow, or incandescence associated with superheated gas emitted from the summit crater, has remained weak and visible only with the aid of a telescope. No movement of the lava flows on the Mi-isi, Bonga and Basud Gullies could be observed as well. These observations of stable summit conditions, sparse rockfall events and lack of movement of the lava flows are consistent with the absence of magma re-supply to the shallow levels of the edifice.  

 

In view of the above, PHIVOLCS-DOST is now lowering the alert status of Mayon from Alert Level 2 to Alert Level 1.  This means that the volcano’s state of unrest has declined to low levels and that the likelihood of an eruption occurring within the immediate future has diminished. However, the lowering of the alert status should not be interpreted that unrest has completely ceased. In the event of a renewed increase in any one or combination of the above monitoring parameters, the alert status may step up once again to Alert Level 2. On the other hand, if there is a noticeable return to baseline levels of ground deformation and sustained low levels of other monitoring parameters, then the alert status may further step down. The public is still reminded to avoid entry into the 6-km Permanent Danger Zone or PDZ due to perennial hazards of rockfalls, avalanches, and sudden steam-driven or phreatic eruption at the summit area. In case of ash fall events that may affect communities downwind of Mayon’s crater, people should cover their nose and mouth with damp, clean cloth or dust mask. Due to the significant amount of volcanic material deposited by the 2023 eruption, heavy rainfall could generate channel-confined lahars and sediment-laden streamflows in rivers draining gullies on which PDC deposits were emplaced. Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft. Furthermore, people living in valleys and active river channels are cautioned to remain vigilant against sediment-laden streamflows and lahars in the event of prolonged and heavy rainfall brought about by the advent of the rainy season. PHIVOLCS-DOST is closely monitoring Mayon Volcano’s activity and any new development will be immediately communicated to all concerned.

 

DOST-PHIVOLCS