Report on Mayon (Philippines) — 7 May-13 May 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 May-13 May 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Mayon (Philippines). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 7 May-13 May 2003. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
On 6 May at 0721 a small explosion occurred at Mayon. The brownish ash-and-steam column produced from the explosion rose about 450 m above Mayon's summit crater and drifted SW. No significant seismicity was recorded prior to the explosion. Electronic tiltmeters on the N and S flanks continued to show inflation of the volcanic edifice. Likewise, a leveling survey conducted on 24 April showed a general inflation of the N flank. Mayon remained at Alert Level 1 (on a scale of 0-5). PHIVOLCS emphasized that the 6-km-radius Permanent Danger Zone remained 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.