Report on Mayon (Philippines) — 5 August-11 August 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 August-11 August 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, 5 August-11 August 2009. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
According to a news article from 6 August, a volcanologist from PHIVOLCS reported that the number of earthquakes from Mayon had decreased, but the volume of sulfur dioxide emissions had increased sharply during the previous 24 hours. On 4 August, sulfur dioxide was emitted at a rate of 707 tonnes per day, down from 915 tonnes per day on 30 July. The rate increased to 1,977 tonnes per day on 5 August. Authorities declared four villages off-limits to people.
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.
Source: Philippine Daily Inquirer