NDRRMC Update SitRep No. 20 re Mayon Volcano Eruption as of 8:00 AM (29 January 2018)
I. SITUATION OVERVIEW
A. Chronological of Events and Eruption Notifications from 13 to 28 January 2018 (TAB A)
B. Current Situation
Between 5:36 AM yesterday to 7:47 PM last night, four (4) episodes of sporadic lava fountaining from the summit crater lasting thirty-six (36) minutes to fifty-seven (57) minutes occurred. The events fed lava flows on the Mi-isi and Bonga Gullies, sprayed near-vent lava spatter, and fed rockfall on the summit area. The lava fountaining events were succeeded by lava effusion in the early morning that fed new lava flow on the Bonga and Miisi Gullies. Heavy rainfall that lasted until the early morning generated channel confined lahars on the Binaan Channel and sediment-laden streamflows in channels draining the volcano edifice due to the remobilization of deposits of pyroclastic density currents or PDCs on the watershed areas.
A total of forty-one (41) volcanic earthquakes, six (6) tremor events, four (4) of which correspond to the lava fountaining events, and sixteen (16) 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.