Report on Mayon (Philippines) — 28 February-6 March 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 February-6 March 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Mayon (Philippines). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 28 February-6 March 2018. 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 27 February-5 March activity at Mayon was characterized by lava effusion from the summit crater, lava fountains, steam and ash emissions, advancing lava flows on the flanks, and pyroclastic flows. Weak and intermittent lava fountains generated steam and ash plumes that rose as high as 800 m and drifted in multiple directions; rumbling sounds were audible at least within a 10-km radius. Active lava flows extended 3.3 km, 4.5 km, and 1.9 km in the Mi-isi (S), Bonga (SE), and Basud (E) drainages, respectively. During 27 February-5 March pyroclastic flows generated by collapses of lava at the fronts and margins of flows traveled 4-5 km down the flanks. On 6 March PHIVOLCS lowered the Alert Level to 3 (on a 0-5 scale) noting a decline in the intensity and frequency of events during the previous week. Data from precise leveling surveys and real-time electronic tilt continued to record deflation of the lower flanks that began on 20 February. The report reminded residents to stay away from the 6-km-radius Permanent Danger Zone and the 7-km Extended Danger Zone on the SSW and ENE flanks.
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.