16 December 2009

8:00 AM

For the past 24 hours, Mayon Volcano’s (13.2576 N, 123.6856 E) activity was characterized by quiet extrusion of lava and rolling down of incandescent lava fragments along Bonga gully. No explosion occurred. At present, the lava front reached about 700 m – 800 m downslope below the crater.  Lava fragments detaching from the lava pile inside the crater continuously  roll down along Bonga gully  reaching about 3 – 4 km downslope of the crater. Sometime, the detached lava fragments produced a small secondary  pyroclastic surge towards the southwest side of the volcano generating light ashfall in the municipalities of Camalig and Guinobatan. Seismic monitoring revealed the occurrence of seventy-eight (78) volcanic earthquakes and tremors. The volcanic earthquakes represent magma ascent towards the crater of the volcano while the tremors were associated to the detached fragments of lava and rockfalls. Emission of weak to moderate volume of white steam that reached height of 200 m above the summit and drifted towards southwest and west-southwest was observed during clear views of the crater yesterday. Measurement of Sulfur Dioxide (SO2) emission rate using FLYSPEC yesterday yielded a value of 750 tonnes per day (t/d).

The status of Mayon Volcano remains hoisted at Alert Level 3.  If trend is one of increasing unrest, hazardous volcanic eruption is possible within weeks. Thus PHIVOLCS-DOST considered 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 southeast 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 southeast 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.