PHIVOLCS reported that during 13-20 March activity at Mayon was mostly characterized by periods of gravity-driven lava advancement, gas-and-steam emissions, rockfalls, and quiescence. Lava flows extended 3.3 km, 4.5 km, and 1.9 km long in the Mi-isi (S), Bonga (SE), and Basud (E) drainages, respectively. Sulfur dioxide emissions were between 969 and 2,077 tonnes/day. Steam-and-gas emissions drifted SW. An episode of lava fountaining was recorded during 0831-0832 on 14 March and produced a light-gray ash plume that rose 200 m above the crater and drifted SW. At 1347 on 16 March a pyroclastic flow traveled 4-5 km down the Mi-isi and Basud drainages. The Alert Level remained at 3 (on a 0-5 scale) and PHIVOLCS 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.

Geological Summary. Symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the most active volcano of the Philippines. The steep upper slopes are capped by a small summit crater. Recorded eruptions since 1616 CE range from Strombolian to basaltic Plinian, with cyclical activity beginning with basaltic eruptions, followed by longer periods of andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic density currents and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often damaged populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)