Mayon Volcano’s seismic activity was characterized by nine (9) explosion-type earthquakes during the past observation period. Due to very thick clouds over the summit, no ash emissions were directly observed although minor ash explosions probably accompanied the seismic events. This is also apparent from confirmed reports that rumbling heard by local residents in Sta Misericordia accompanied the explosion-type quakes which occurred at 3:04AM and 3:06AM. In addition, the seismic network recorded two (2) low frequency volcanic earthquakes associated with shallow movement of magma. Sulfur Dioxide (SO2) flux emission rates averaged 1,740 tonnes per day (t/d), similar to 1,687 t/d measured last 28 November 2005. These values are still significantly above the usual 500 t/d.

Due to the continuing active seismicity involving minor explosion events, PHIVOLCS interprets the volcano to be undergoing moderate unrest, brought about by some magma ascent intruding the summit area. However, should rates of seismic, surface and other volcanic activity significantly change, PHIVOLCS shall elevate its notice of alert status accordingly. Alert Level 2 remains hoisted over the volcano, which means that the public is strongly advised not to enter the six (6) kilometer radius Permanent Danger Zone (PDZ) especially in the southeast sector of the volcano where the crater rim is at its lowest. Residents just outside the PDZ are also advised to be vigilant against sudden explosions which could generate hazardous volcanic flows.

August 25th, 2004

PHIVOLCS reported on 23 August that an aerial survey of Mayon conducted on 17 August revealed that lava had accumulated within the volcano's summit crater. The lava dome was extruding very slowly and the volume of lava was contained within the crater. PHIVOLCS warned that the volcano remains at Alert Level 2, and that people cannot enter the Permanent Danger Zone of 6 km radius around the volcano. As of the 18th of February, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported that at approximately 1950 yesterday, the very faint glow at the summit of Mayon intensified slightly. The brighter incandescence was observable from Lignon Hill Volcano Observatory and in Legaspi City proper and coincided with a slight increase in the overall background tremor detected by seismographs around the volcano. However, no significant changes were recorded by ground deformation and SO2 measurements. In the latter Sulfur Dioxide (SO2) remained only slightly above baseline at 829 tonnes per day as of 06 September 2004. The above observations indicate a possible renewed episode of volcanic unrest, probably due to small incremental intrusion of magma at shallow depths that caused the intensified summit glow. Small explosions, similar to the events of 03 June and 22 July this year, may therefore be expected as pockets of gas beneath the crater are suddenly released. At this stage, Alert Level 2 remains hoisted over Mayon Volcano which means a low level of unrest as suggested by seismicity, ground deformation and other parameters. PHIVOLCS reminds the general public to refrain from venturing into the six-kilometer Permanent Danger Zone (PDZ) because life-threatening volcanic flows may occur with little or no warning. The colour code at Mayon is currently at ALERT LEVEL 2 . Information : PHIVOLCS