PHIVOLCS raised the Alert Level at Mayon from 1 to 2 (on a scale of 0-5) on 11 October after incandescence was seen in the E portion of the volcano's crater, sulfur-dioxide emission rates increased from ~1,600 tons on 1 October to ~2,380 tons on 9 October, and the number of volcanic earthquakes had been increasing slightly for several weeks. PHIVOLCS believes that slow magma intrusion may be occurring. The 6-km-radius Permanent Danger Zone remained 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.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)