Report on Mayon (Philippines) — 10 January-16 January 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 10 January-16 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, 10 January-16 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)
An aerial survey by the Philippine Institute of Volcanology and Seismology (PHIVOLCS) on 10 January confirmed the presence of a lava dome inside the summit crater. The lava dome appeared to have a spiny, blocky surface, was emitting voluminous steam, and exhibited slight incandescence. The SO2 emission rate was 2,300 metric tons per day (t/d), high above the 500 t/d level usually observed during quiescent periods. Seismicity related to dome growth remained significant. Deformation measured by electronic tiltmeters on the N flank indicated intrusion of magma into the upper levels of the volcano. Similar activity continued through the 15th. Alert Level 2 (sustained unrest with indications of magmatic activity) remained 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.