Report on Mayon (Philippines) — 4 April-10 April 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 April-10 April 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, 4 April-10 April 2001. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
The last reported observations of Mayon by the PHIVOLCS occurred on 6 April. At 0754 a small eruption produced an ash puff that reached 200 m above the crater rim before drifting to the WSW. The same day 17 low-frequency volcanic earthquakes were recorded and ~2,600 metric tons of SO2 were measured, a value significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. The crater was visible, but no glow was observed. Moderate steaming was typical. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone.
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.