Report on Mayon (Philippines) — 17 December-23 December 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 December-23 December 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Mayon (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 17 December-23 December 2014. Smithsonian Institution and US Geological Survey.
13.257°N, 123.685°E; summit elev. 2462 m
All times are local (unless otherwise noted)
On 19 December PHIVOLCS reported that since the last seismic swarm detected at Mayon on 29 November a general decline in the overall activity was noted. Specifically, for the previous three weeks, seismic activity had declined to an average 2-3 mostly volcano-tectonic earthquakes daily, few low-frequency earthquakes were detected, and a few minor rockfall events occurred; deformation data did not indicate magma intrusion; sulfur dioxide emissions had declined on 2 October to below 500 tonnes/day which is the baseline value during periods of quiescence; no lava flows had been observed since 19 October. The Alert Level was lowered to 2 (on a 0-5 scale). PHIVOLCS reminded residents of the 6-km-radius Permanent Danger Zone (PDZ) around the volcano.
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.