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Report on Mayon (Philippines) — 8 September-14 September 2004


Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
8 September-14 September 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, 8 September-14 September 2004. Smithsonian Institution and US Geological Survey.

Weekly Report (8 September-14 September 2004)



13.257°N, 123.685°E; summit elev. 2462 m

All times are local (unless otherwise noted)

On 12 September, faint glow was visible at Mayon's summit that coincided with a slight increase in overall background tremor. According to PHIVOLCS, these observations indicated a possible renewed episode of volcanic unrest, probably due to small incremental intrusions of magma at shallow depths that caused the intensified glow at the summit. They reported that small explosions, similar to the events on 3 June and 22 July 2004, may be expected as pockets of gas beneath the crater are suddenly released. There were no significant changes in ground deformation or sulfur-dioxide flux. According to a news report, volcanic material was emitted from Mayon late on 12 September, setting fire to grass on the volcano's slopes. People were reminded to remain outside of the 6-km Permanent Danger Zone. Mayon was at Alert Level 2 (on a scale of 0-5).

Geological Summary. Symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the most active volcano of the Philippines. The steep upper slopes are capped by a small summit crater. Recorded eruptions since 1616 CE 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 damaged populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)