Report on Mayon (Philippines) — 12 May-18 May 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 May-18 May 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Mayon (Philippines). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 12 May-18 May 2004. 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, PHIVOLCS reported that three volcanic earthquakes were recorded at Mayon during the week of 9 May, suggesting a renewed period of unrest. In addition, incandescence was visible in the crater and moderate steaming was seen. On 12 May, the sulfur-dioxide flux increased from the normal level of ~500 tons per day to ~1,170 tons. People were reminded not to enter the 6-km-diameter Permanent Danger Zone around Mayon.
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: ABS-CBN News