PHIVOLCS reported that during 31 January-6 February daily activity at Mayon continued to be characterized by lava effusion from the summit crater, rockfalls, pyroclastic flows (31 January-1 February), ash and steam emissions, advancing lava flows on the flanks, and weak and sporadic lava fountains. Numerous rockfall events were generated by the growing and collapsing summit lava dome and from the front and margins of advancing lava flows. On 31 January pyroclastic flows traveled as far as 2 km in the Mi-isi (S), Basud (E), and Bonga (SE) drainages. White-to-light-gray ash plumes generally rose to low heights, though five events generated ash plumes that rose as high as 1 km above the crater rim. An event on 2 February also produced an ash plume that rose 1 km. The first of two lava fountaining events on 4 February lasted sporadically for 114 minutes, generated an ash plume that rose 500 m, and produced booming sounds heard within a 10-km radius. During 5-6 February high volumes of effused lava extended the lava flows in the Mi-isi, Bonga-Buyuan, and Basud drainages to 3.2, 4.5, and 3 km, respectively. The Alert Level remained at 4 (on a 0-5 scale) and the public was warned to remain outside of the Danger Zone defined as an area within an 8-km radius.

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 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 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)