Report on Mayon (Philippines) — 23 December-29 December 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 December-29 December 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Mayon (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 23 December-29 December 2009. 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 23-29 December about 240 explosions from Mayon were seen during times of good visibility. Off-white, brownish, or grayish ash plumes rose as high as 2 km above the crater rim and drifted W and SW. Lava flowed down the Bonga-Buyuan (SE), Miisi (S), and Lidong (ESE) gullies, and on 29 December was 5.8 km from the summit crater in the Buyuan channel. Intermittent rumbling and booming noises were noted and seismicity continued to be elevated. Detached incandescent fragments descended the flanks. Sulfur dioxide emissions fluctuated between about 2,300 and 9,000 tonnes per day. On 24 December lava fountains rose 500 m above the summit crater. Three pyroclastic flows on 25 December traveled 2 km.
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.