Report on Mayon (Philippines) — 21 February-27 February 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 February-27 February 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, 21 February-27 February 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 during the week the number of earthquakes recorded at Mayon was similar to the previous week, and lower SO2 emission rates were recorded. Between 6 and 30 low-frequency volcanic earthquakes were recorded daily during 21-26 February. SO2 emission rates decreased from a maximum value of ~3,000 metric tons per day (t/d) on 20 February, to 1,700 t/d on 21 February. The minimum value was ~1,000 t/d on 24 February. During the week there was an inflationary trend at Mayon's edifice and no incandescence was observed at the volcano's crater. Weak-to-moderate steaming was occasionally observed. Mayon remained at Alert Level 3 (on a scale of 0-5).
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.