On 14 Dec 2009, an increased volcanic activity was recorded by the Philippine Institute of Volcanology and Seismology (PHILVOLCS), prompting scientists to raise the Alert Level of Mount Mayon from 2 to 3. As a result of these developments, a mandatory evacuation was reinforced for households in all areas within the 6-km radius Permanent Danger Zone (PDZ) and the 8-km Extended Danger Zone (EDZ), about 9,946 families or 47,285 individuals in the Southeast Quadrant, particularly, in Buyuan, Mabinit and Bonga areas.
On 20 Dec 2009, Mount Mayon's volcanic activity escalated with the increased number and size of seismic activities. A total of 1,942 volcanic earthquakes was detected by the seismic network. Sulfur dioxide emission rate remained very high at 6,089 tonnes per day while audible booming and rumbling sounds were reported in the eastern flank of the volcano. (IFRC, 22 Dec 2009)
On 2 Jan 2010 PHIVOLCS had lowered the alert level of Mayon Volcano from Alert Level 4 to Alert Level 3 to reflect the overall gradual decrease of activity. (Government of the Philippines, 4 Jan 2010)