Mayon Volcano Bulletin

18 August 2006

8:00 AM

Mayon Volcano (13.2576°N, 123.6856°E) produced six (6) explosions in the past 24 hours.  These events occurred at 1:11AM, 2:15AM, 2:17AM, 2:31AM, 3:01AM and 3:13AM. Throughout this observation, lava continued to flow from the summit crater into the Bonga gully and a significant amount of lava fragments were also seen detaching from the crater and lava flow deposits.  In general, lava fragments were deposited onto the midslopes although some blocks came to rest at around 800 meters elevation.  The Mabinit/Bonga lava flow continues to advance very slowly and the toe of the lava deposit is estimated to have reached some 6.8 kilometers from the crater.

Earthquake sensors recorded 307 tremor episodes, which were mainly caused by lava extrusion and rockfall activity.  The number of volcanic earthquakes remained significantly high at 32, and the character of earthquake activity represented magma ascent into the cone.  The Sulfur Dioxide (SO2) emission rate of the plume remains high at 2,937 tonnes per day (t/d) although this is considerably lower than the previous day’s measurement of 8,086 t/d.  The emission rate of this type of gas is associated with active magma degassing.

The explosion events, lava extrusion, earthquake activity and gas emission activity confirm that Mayon remains at a very high level of unrest which may evolve into more vigorous and explosive activity.  Thus, Alert Level 4 is still in effect, which means that a hazardous explosive eruption may occur anytime.  PHIVOLCS reminds the public that the eight (8) kilometer radius - EXTENDED DANGER ZONE (EDZ) in the southeast sector of the volcano should continue to be off-limits. At other areas around the volcano, this EDZ is seven (7) kilometers from the summit crater.  Residents of areas just outside and adjacent to the EDZ are also  advised to be on the alert for updates regarding their status for possible evacuation in case volcanic activity intensifies.