Report on Mayon (Philippines) — 19 July-25 July 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 19 July-25 July 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, 19 July-25 July 2006. 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 19-24 July lava flows from Mayon traveled SSE a maximum distance of 4 km from the summit toward the Bonga gully and branched off to the W and E. Incandescent blocks shed from the toe and margins of the flows were visible at night and traveled SE. Ash plumes generated from the rolling blocks produced light ash fall 8.5 km E of the summit in Sta. Misericordia. On 20 July, pyroclastic flows were observed on the SE slopes prompting ~100 families to evacuate. On 22 July, lava flows advanced SE towards the Mabinit channel. The lava flows were within the 6 km radius Permanent Danger Zone.
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.