Mayon Volcano Bulletin

04 August 2006

9:00 AM

Lavas from Mayon Volcano (13.2576°N, 123.6856°E) are being deposited onto the southeast upper and middle slopes of the volcano, in the general directions of Barangays Miisi and Buyoan. The main lava being extruded is slowly flowing along the Mabinit/Bonga channel and has reached some 30 meters beyond the six (6) kilometer-radius Permanent Danger Zone at elevation 275 meters above sea level.

Voluminous steaming accompanied lava extrusion. The emission rate of Sulfur Dioxide (SO₂) decreased from 4,760 tonnes per day (t/d) to 2,965 t/d. This decrease by itself, however, is not an indication of waning because other indicators show sustained activity.

The seismicity was dominated by surface events of about 354 tremors caused by falling lava blocks onto the volcano’s slopes. The number of earthquakes from inside the volcano decreased to 18 although some of these were notably larger in magnitude.

Some minor collapse of lava deposits were observed and these generated clouds of ash and steam swept by winds over various directions. Some of the Barangays to the southeast and east of Mayon therefore experienced very light ashfall. With accumulation of lavas within the upper southern sector of the volcano, more collapse events are expected.

Alert Level 3 remains in effect, which means that the six (6) kilometer radius Permanent Danger Zone (PDZ) remains off-limits.  As lava continues to descend beyond the PDZ boundary in the southeast, PHIVOLCS reminds everyone to keep a safe distance because sudden collapse of the front and sides of the advancing flow deposit may produce some pyroclastic avalanches which could impact areas well beyond the lava flow’s edge.  Although the lava flow is moving slowly, it has entered vegetated areas and has produced some small fires as trees and shrubs are consumed. PHIVOLCS therefore reminds the public to be also aware of potential spread of fire in the upper reaches of Mabinit and Bonga. Residents of barangays within 8 kilometers in the southeast sector of the volcano, particularly in the towns of Daraga and Sto. Domingo and in Legaspi City, are therefore advised to be alert and to be prepared for evacuation if activity escalates.