Report on Mayon (Philippines) — 9 August-15 August 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 August-15 August 2006
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2006. Report on Mayon (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 August-15 August 2006. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
During 9-15 August, explosive activity continued at Mayon after a brief respite on 8 August. Based on interpretations of seismic data, minor explosions during 9-11 and 13-15 August were accompanied by lava extrusion and collapsing lava flow fronts that produced blocks and small fragments. Visual observations were usually obscured by clouds, but on 11 August an ash plume was seen drifting ESE. On 12 August, out of four explosions that occurred, one produced a pyroclastic flow that traveled over the SE and E slopes and generated a plume that rose 500 m high and drifted NE. On 15 August, a brief break in the clouds allowed for a view and confirmation of fresh pyroclastic deposits from activity the previous days. About 40,000 people remained in evacuation centers. The Extended Danger Zone of 8 km in the SE sector was still in effect.
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.