PHIVOLCS: MAYON VOLCANO BULLETIN 02 February 2018 8:00 A.M.PHIVOLCS has raised the alert level to Alert Level 4 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 stream flows along channels draining the edifice.
Sporadic and weak lava fountaining, continuous lava effusion and degassing from the summit crater characterized Mayon’s activity yesterday. Much of the activity produced low white to light-gray plumes, with the exception of four events that produced 750 to 1500 meter-tall gray ash plumes at 6:04 AM, 7:56 AM, 8:51 AM and 9:11 PM accompanied by loud booming sounds audible within 10 kilometers of the summit crater. Eleven (11) episodes of lava-collapse pyroclastic density current (PDC) events were visually observed between 8:51 AM yesterday and 2:01 AM this morning depositing along Miisi, Basud and Bonga Gullies within two kilometers of the summit crater. Throughout the night, quiet lava effusion fed lava flows and rockfall in the Miisi and Bonga-Buyuan channels and barrancos between these. The Miisi and Bonga-Buyuan lava flows have advanced to 3.2 kilometers and 4.0 kilometers, respectively, from the summit crater.
A total of three hundred thirty eight (338) volcanic earthquakes, most of which corresponded to sporadic and weak fountaining events, two (2) tremor events, eleven (11) distinct episodes of PDC generation from lava collapse and two (2) 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 flows on the Bonga and Miisi Gullies.