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00 volcano icon for bulletin  This serves as a notice for the lowering of the alert status of Kanlaon Volcano from Alert Level 2 (Moderate Level of Unrest) to Alert Level 1 (Low Level of Unrest).

 

Following unrest characterized by increased volcanic earthquakes between November 15 and December 26, 2017 and inflation of the upper slopes in December 2017 based on continuous GPS observation, Kanlaon Volcano has been exhibiting a protracted decline in overall activity. This trend is supported by these observation parameters:

1. Volcanic Earthquake Activity: Despite elevated seismicity recorded on January 4 and 5, April 16, June 27, August 16, and December 8 and 12, the seismic activity in the year 2018 was generally declining to low levels (average of ~4 earthquakes/day) but presently remains above baseline levels of 0-2 volcanic earthquakes/day. Much of the seismicity emanated from shallow sources within and beneath the volcanic edifice.

2. Ground Deformation: Recent data from continuous GPS measurements show inflation of the edifice but at a significantly slow rate, which is more likely due to the pressurization from a shallow hydrothermal system.

3. Volcanic Gas Emission: Sulfur Dioxide emission or SO2 flux from Kanlaon crater based on campaign gas spectrometry has waned from a high of 5129 tonnes/day in 29 December 2017 to an average of 482 tonnes/day since June 2018. The latest flux was recorded at 122 tonnes/day on December 2018. The relatively low levels of SO2 flux indicate current passive degassing from the hydrothermal system, rather than directly of stored magma, beneath the edifice.

4. Visual Observation of the Summit: Active steam-dominated degassing from the summit crater has been weak to moderate since 26 December 2017, consistent with a decline in hydrothermal activity.

 

In view of the above observations, PHIVOLCS is now lowering the alert status of Kanlaon Volcano from Alert Level 2 to Alert level 1. This means that observational parameters have returned to low levels and no magmatic eruption is foreseen in the immediate future. However, 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. The public is still reminded to avoid entry into the 4-kilometer radius Permanent Danger Zone (PDZ) due to perennial hazards of rockfalls, avalanches, sudden outgassing and steam-driven or phreatic eruption at the summit area. DOST-PHIVOLCS is closely monitoring Kanlaon’s condition and any new development will be immediately communicated to all concerned.