Report on Mayon (Philippines) — 14 May-20 May 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 May-20 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, 14 May-20 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 14 May at 1813 a small and brief explosion at Mayon's summit crater produced a small NW-drifting ash puff that rose less than 100 m above the crater. Two seismic stations recorded this as a small-amplitude event. PHIVOLCS stated that there had been a succession of minor emissions in the past few months and that ongoing unrest may lead to more vigorous activity. The Alert Level remained at 1 (on a scale of 0-5), but PHIVOLCS indicated it would consider increasing the Alert Level if the current pace of unrest is sustained.
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.