Report on Mayon (Philippines) — 12 March-18 March 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 March-18 March 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, 12 March-18 March 2003. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
PHIVOLCS raised the Alert Level at Mayon from 0 to 1 (on a scale of 0-5) after an explosion occurred on 17 March at 1819. The brief burst of ash and steam rose to ~1 km above the summit and drifted WNW. Prior to the explosion no significant seismicity was recorded. During 0900-1100 SO2 emission rates were higher than normal at 890 tons per day (500 tons are normally measured during repose), and electronic tiltmeters on the volcano's N and S flanks indicated a slight inflation of the edifice beginning on 13 March. PHIVOLCS emphasized that the 6-km-radius Permanent Danger Zone was 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.