Report on Mayon (Philippines) — 31 January-6 February 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 January-6 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, 31 January-6 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 31 January-6 February daily activity at Mayon continued to be characterized by lava effusion from the summit crater, rockfalls, pyroclastic flows (31 January-1 February), ash and steam emissions, advancing lava flows on the flanks, and weak and sporadic lava fountains. Numerous rockfall events were generated by the growing and collapsing summit lava dome and from the front and margins of advancing lava flows. On 31 January pyroclastic flows traveled as far as 2 km in the Mi-isi (S), Basud (E), and Bonga (SE) drainages. White-to-light-gray ash plumes generally rose to low heights, though five events generated ash plumes that rose as high as 1 km above the crater rim. An event on 2 February also produced an ash plume that rose 1 km. The first of two lava fountaining events on 4 February lasted sporadically for 114 minutes, generated an ash plume that rose 500 m, and produced booming sounds heard within a 10-km radius. During 5-6 February high volumes of effused lava extended the lava flows in the Mi-isi, Bonga-Buyuan, and Basud drainages to 3.2, 4.5, and 3 km, respectively. 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.