PHIVOLCS raised the Alert Level at Mayon from 0 to 1 (on a scale of 0-5) after an explosion occurred on 17 March at 1819. The brief burst of ash and steam rose to ~1 km above the summit and drifted WNW. Prior to the explosion no significant seismicity was recorded. During 0900-1100 SO2 emission rates were higher than normal at 890 tons per day (500 tons are normally measured during repose), and electronic tiltmeters on the volcano's N and S flanks indicated a slight inflation of the edifice beginning on 13 March. PHIVOLCS emphasized that the 6-km-radius Permanent Danger Zone was in effect.

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.

Sources: Associated Press, Philippine Institute of Volcanology and Seismology (PHIVOLCS)