Philippines

Philippines: NDCC Update - Sitrep No. 11 Mayon Volcano update

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DATE: 22 December 2009 as of 8:00 AM

Sources: DOST-PHIVOLCS, DSWD. DOH, DepEd, OCDRC-V, ALBAY PDCC, AFP, JTF MAYON, DPWH V

I. CHRONOLOGY OF EVENTS

- September 2006: Reverted to Alert Level 1 (progressively downgraded from Level 4 in July 04, 2006) and maintained since then up to July 2009

- August 10, 2009: Alert Level 1 (Minor mild explosion)

- July 10, 2009: Alert Level 2 (Due to continued state of unrest which could lead to ash explosion or eventual hazardous magmatic eruption)

- Nov. 11 - 12, 2009: Alert Level 2 (4 ash explosions, Mt. Mayon remained inflated, above normal S02 level, visible crater glow, seismic activity, 1,900 families evacuated)

- December 14, 2009: Alert Level 3 (8:00 PM, 5 series of ash explosion and lava flow, increase S02 and seismic activities)

- December 20, 2009: Alert Level 4 (hazardous explosive eruption is possible within days. Thus, areas expected to be affected by such eruption will be accordingly extended)

II. SITUATION OVERVIEW

- Mayon Volcano is under Alert Level 4. To ensure the safety of the public, PHIVOLCS-DOST is recommending an extended danger zone from the summit of 8 km at the southern sector and 7 km at the northern sector

Observations:

- Mayon Volcano activity escalated during the past 24-hour, seismic activity dramatically increased in number and size. A total of 1,942 volcanic quakes and tremors were recorded by the seismic network. Many of these volcanic earthquakes were recorded at maximum deflection and continually occurred beginning at 12:21 PM, 20 December 2009

- Harmonic tremors were continuously recorded by the seismic instruments

- Audible booming and rumbling sounds were first reported in the eastern flank of the volcano at about 2:55PM, December 19, 2009 then occasionally occurred beginning 11:00 PM, December 20, 2009

- Intensified crater glow and rolling down of incandescent fragments from the crater was also persistent. Red hot lava continuously flowed down along the Bonga-Buyuan, Miisi and Lidong gullies

- Lava fountains rising approximately 200 meters above the crater were observed. The lava front has now reached about 5 kilometers downslope from the summit along the Bonga-Buyuan gullies

- Sulfur dioxide (SO2) emission rate remained very high at 6,089 tonnes per day (t/d)

Recommendations

- Since the persistent high unrest is evident and the possibility of volcanic eruption is high, PHIVOLCS strongly recommends that the 6-km radius Permanent Danger Zone (PDZ) around the volcano be extended, thus, the Extended Danger Zone (EDZ) from the summit of 8 km at the southern sector and 7 km at northern sector. This area should be free from human activity because of sudden explosions that may generate hazardous volcanic flows

- Areas just outside of the EDZ should prepare for evacuation in the event explosive eruptions intensify

- 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

AFFECTED/DISPLACED POPULATION (Tab A)

- As of 8:00 PM, 22 December 2009, a total of 9,428 families / 45,267 persons have been evacuated to the 27 designated evacuation centers