Report on Mayon (Philippines) — 14 February-20 February 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 February-20 February 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Mayon (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 14 February-20 February 2018. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
PHIVOLCS reported that during 14-20 February daily activity at Mayon continued to be characterized by lava effusion from the summit crater, rockfalls, lava fountains, steam emissions, advancing lava flows on the flanks, and pyroclastic flows. Weak and sporadic lava fountaining events each lasted between 5 and 239 minutes, and were sometimes accompanied by rumbling sounds audible with a 10-km radius. Heavy rainfall on 14 February caused lahars in the Anoling drainage, and sediment-laden streams in most channels where pyroclastic flow deposits were emplaced. During 16-17 February lava fountains were 200-500 m tall and generated steam plumes that drifted SW, WSW, and NW. A lava-fountaining event that began at 0103 on 17 February lasted for 12 hours and 18 minutes. Lava flows 3.3 km, 4.5 km, and 900 m long in the Mi-isi (S), Bonga (SE), and Basud (E) drainages, respectively, continued to be active. Pyroclastic flows traveled 4.2-4.6 km in the Mi-isi, Bonga, and Basud drainages. The Alert Level remained at 4 (on a 0-5 scale) and the public was warned to remain outside of the Danger Zone, defined as an area within an 8-km radius.
Geologic Background. Beautifully symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the Philippines' most active volcano. The structurally simple edifice has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions date back to 1616 and range from Strombolian to basaltic Plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.