Mayon Volcano Update

11 September 2006

5:00 PM

This is a notice for the lowering of alert status of Mayon Volcano.

After the ash explosion of 01 September, a general decline in the overall activity of Mayon has been established. The decrease in key parameters such as seismicity, gas (Sulfur Dioxide) emission rates and ground inflation all indicate a waning condition. The slowdown in the eruptive activity is also evident from the decrease in intensity of crater glow and the diminishing volume of lava being extruded from the summit.

In view of the foregoing decrease in the tempo of unrest, PHIVOLCS is lowering the alert status of Mayon Volcano from Alert Level 4 to ALERT LEVEL 3. This means a diminished probability for a hazardous major eruption. Corollary to this announcement, PHIVOLCS also recommends smaller exclusion zones defined by the following:

1. For areas previously declared off-limits up to 8 kilometers from the summit, the new Extended Danger Zone (EDZ) is now reduced to 7 kilometers. This is applicable for areas in the southeast including Barangays Mabinit, Bonga, Matanag and Buyoan, all in Legazpi City,

2. For other areas not covered in item 1 above, the 7 kilometer radius Extended Danger Zone (EDZ) is now removed. The 6 kilometer-radius Permanent Danger Zone is now in effect.

Although the alert status of Mayon has been lowered, PHIVOLCS reminds the public that Mayon remains in an eruptive state because lava continues to extrude from the summit crater. Such activity makes it possible for pockets of gas-rich magma to be released explosively. There is therefore a continuing threat of sudden explosion which could produce pyroclastic flows. The crater rim facing the southeast is still lower than at other directions so that any volcanic flow emanating from the crater or from lava deposits of the upper and midslopes could threaten communities in the southeast. In addition, lava deposits facing Barangays Mabinit and Bonga remain hot and mobile. Thus, the margins of the lava flow deposits are susceptible to collapse and may produce small pyroclastic avalanches which may affect areas beyond the existing lava deposits. Residents of these Barangays are reminded to be on full alert.

Mayon Volcano remains at an elevated state of unrest. The new Extended Danger Zone of 7 kilometers covering the southeast and the 6 kilometer-radius Permanent Danger Zone for all other areas around the volcano should remain off-limits.