|Mayon Volcano Bulletin 4|
|Friday, 18 December 2009 18:20|
Mayon Volcano (13.2576 N, 123.6856 E) manifested an increase in its activity during the past observation period. A total of two hundred forty eight (248) volcanic quakes and tremors were recorded by the seismic network. Fifty (50) of these events were explosion type, however, only seven (7) were observed during times of good visibility. These explosions produced dark gray to dark brown ash columns that reached a maximum height of up to 1000m above the summit before drifting towards southwest. Harmonic tremors were continuously recorded by the seismic instruments.
During the cloud break this morning, steaming activity ranged from dirty white to light brown in color. Night observation showed an intensified crater glow.
The advancing lava flow has now reached approximately 3 kilometers downslope from the crater while incandescent fragments from the lava pile continuously roll down along Bonga Gully reaching about 3-4 kilometers downslope. Sulfur Dioxide (SO2) emission rate was still high at 1,065 tonnes per day (t/d).
Alert Level 3 remained hoisted over Mayon Volcano. Since an increasing trend is noticeable at present, the possibility of hazardous volcanic eruption is high. Thus, PHIVOLCS-DOST recommends that the 6-km radius Permanent Danger Zone (PDZ) around the volcano and the 7-km Extended Danger Zone (EDZ) on the southeast flank of the volcano should be free from human activity because of sudden explosions that may generate hazardous volcanic flows. In addition, areas in the south that are outside the 7 kilometer danger zone but within 8 kilometers of the crater should be extra alert for increased volcanic activity. Active river channels and those perennially identified as lahar prone in the southern sector should also be avoided especially during bad weather conditions or when there is heavy and prolonged rainfall. PHIVOLCS–DOST is closely monitoring Mayon Volcano’s activity and any new significant development will be immediately posted to all concerned.