Mayon Volcano Update

13 August 2006

8:00 AM

Four (4) ash explosions occurred at Mayon Volcano (13.2576°N, 123.6856°E) from 6AM yesterday to 6AM today. These explosions occurred at 1:30 PM, 4:13PM, 5:31PM and 11:31PM. The 4:13PM event produced a pyroclastic flow (“oson”) which swept the southeastern and eastern slopes of the volcano. The resultant grayish ash clouds then rose to about 500 meters high and drifted northeast. Other events were not observed due to thick rain clouds covering the middle slope and summit crater of the volcano although the seismographs recorded all these explosions.

Ten (10) volcanic earthquakes and 324 tremor episodes were recorded during the same observation period. The volcanic earthquakes indicated active magma ascent into the crater while lava fragments which detached from the lava flow deposits generated the tremors. The Sulfur Dioxide (SO₂) emission rate was 3,423 tonnes per day (t/d), a decrease by more than half of the previous day’s value.

The explosions and significant drop in SO₂ emission rate indicate a continuing high unrest of the volcano.

The public is reminded that Alert Level 4 is still in effect, which means that a hazardous explosive eruption may occur anytime. Thus, the eight (8) kilometer - EXTENDED DANGER ZONE (EDZ) in the southeast sector of the volcano should be observed at all times. In this regard, PHIVOLCS reminds everyone to observe safety precautions relevant with this alert level. At other areas around the volcano, this EDZ is seven (7) kilometers from the summit crater. Areas outside of the EDZ are advised to be on the alert for updates regarding their status for possible evacuation in case volcanic activity intensifies.