Between 06:26 AM to 01:40 PM yesterday, three (3) episodes of sporadic lava fountaining from the summit crater lasting twenty-four (24) minutes to forty (40) minutes occurred. The lava fountains generated ash plumes that reached 3 kilometers above the crater. The events fed lava flows on the Mi-isi and Bonga Gullies, sprayed near-vent lava spatter, and fed rockfall on the summit area. Only one (1) pyroclastic density current or PDC on the Miisi Gully was observed. Lava fountaining episodes transitioned into aseismic lava effusion in the early evening, feeding incandescent lava flows on the Bonga and Miisi Gullies, the former of which advanced significantly downslope.
A total of ten (10) volcanic earthquakes, twenty-one (21) tremor events, three (3) of which correspond to the lava fountaining events, one (1) PDC from lava collapse, and twenty-one (21) rockfall events were recorded by Mayon's seismic monitoring network. Rockfall events were generated by the collapsing lava front and margins of the advancing lava flow on the Bonga and Miisi Gullies. Currently, the Miisi and Bonga lava flows have maintained their advance to three (3) and 1.8 kilometers, respectively, from the summit crater. Sulfur dioxide gas emission was measured at an average of 1,916 tonnes/day on 25 January 2018. Electronic tilt and continuous GPS measurements indicate a sustained swelling or inflation of the edifice since November and October 2017, consistent with pressurization by magmatic intrusion.
Alert Level 4 remains in effect over Mayon Volcano. The public is strongly advised to be vigilant and desist from entering the eight (8) kilometer-radius danger zone, and to be additionally vigilant against pyroclastic density currents, lahars and sediment-laden streamflows along channels draining the edifice. Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden eruption can be hazardous to aircraft. DOST-PHIVOLCS maintains close monitoring of Mayon Volcano and any new development will be communicated to all concerned stakeholders.
