Report on Mayon (Philippines) — 24 January-30 January 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 January-30 January 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Mayon (Philippines). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 24 January-30 January 2001. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
PHIVOLCS reported that the increase in volcanic activity, which has occurred since a lava dome was spotted in Mayon's summit crater on 10 January, led them to raise the Alert Level from 2 to 3 (an increased tendency towards eruption, with magmatic outbursts possible within the coming weeks) on 25 January. During the previous week the monitoring networks had detected numerous volcanic earthquakes, continued inflation at the edifice, and very high gas emission from the summit crater (5,040 metric tons per day). In addition, several ash ejections coincided with earthquakes that originated from beneath the lava dome, which appeared to grow during the week. The ash-laden volcanic plumes typically rose up to 500 m above the crater and generally drifted with the prevailing wind to the WNW and NW.
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.