MAYON VOLCANO ADVISORY
11 November 2009
7:00 A.M.
This is to notify the public and concerned authorities on the current activity of Mayon Volcano.
At 1:58 AM today, an ash explosion occurred at the summit crater of Mayon Volcano (13.2576 N, 123.6856 E). This event was recorded by the seismic network as explosion type earthquake which lasted for about three minutes and accompanied by rumbling sounds. Incandescent rock fragments at the upper slope were observed in Brgy. Lidong of Sto. Domingo, Brgys. Tumpa and Anoling of Camalig. Ash column was not observed due to cloud cover. Field investigation conducted after the event showed ashfall drifted towards the Southwest quadrant of the volcano due to the prevailing Northeast monsoon. Barangays affected by traces of ashfall were brgy. Tumpa of Camalig, Brgys. Travesia, Maipon, Masarawag, Doña Tumasa, Muladbukad Grande, and Pequeño of Guinobatan, Brgys. Nabonton and Nasisi of Ligao. Light ashfall was also noted at Brgy. San Rafael of Guinobatan. For the past 24 hours, the seismic network recorded twenty (20) volcanic earthquakes.
The status of Mayon Volcano remains at Alert Level 2. This means a state of unrest which could lead to more ash explosion or eventually to hazardous magmatic eruption. Thus PHIVOLCS strongly 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 are off-limits due to the threat from sudden explosions and rockfalls from the upper slope. Active river channels and those areas perennially identified as lahar prone in the southeast sector should also be avoided especially during bad weather condition or when there is heavy and prolonged rainfall.
In case of asfall, residents in affected areas should stay indoor or cover their nose with clean wet cloth or dust mask.
Any new development will be posted and relayed immediately to all concerned authorities.
Showing posts with label eruption. Show all posts
Showing posts with label eruption. Show all posts
Wednesday, November 11, 2009
Mayon Volcano Alert Levels
MAYON VOLCANO ALERT LEVELS
ALERT LEVEL MAIN CRITERIA INTERPRETATION/RECOMMENDATION
0
No Alert. Quiet.
All monitored parameters within background levels. No eruption in foreseeable future.
Entry in the 6-km radius Permanent Danger Zone (PDZ) is not advised because phreatic explosions and ash puffs may occur without precursors.
1
Abnormal Low level unrest.
Slight increase in seismicity.
Slight increase in SO2 gas output above the background level.
Very faint glow of the crater may occur but no conclusive evidence of magma ascent.
Phreatic explosion or ash puffs may occur. No eruption imminent.
Activity may be hydrothermal, magmatic or tectonic in origin.
No entry in the 6-km radius PDZ.
2
Increasing Unrest - Moderate unrest.
Low to moderate level of seismic activity.
Episodes of harmonic tremor.
Increasing SO2 flux.
Faint / intermittent crater glow.
Swelling of edifice may be detected.
Confirmed reports of decrease in flow of wells and springs during rainy season. Unrest probably of magmatic origin; could eventually lead to eruption.
6-km radius Danger Zone may be extended to 7 km in the sector where the crater rim is low.
3
Increased Tendency Towards Eruption - Relatively high unrest.
Volcanic quakes and tremor may become more frequent.
Further increase in SO2 flux.
Occurrence of rockfalls in summit area.
Vigorous steaming / sustained crater glow.
Persistent swelling of edifice. Magma is close to the crater.
If trend is one of increasing unrest, eruption is possible within weeks.
Extension of Danger Zone in the sector where the crater rim is low will be considered.
4
Hazardous Eruption
Imminent Intense unrest.
Persistent tremor, many "low frequency"-type earthquakes.
SO2 emission level may show sustained increase or abrupt decrease.
Intense crater glow. Incandescent lava fragments in the summit area. Hazardous eruption is possible within days.
Extension of Danger zone to 8 km or morein the sector where the crater rim is low will be recommended.
5
Hazardous Eruption
Hazardous eruption ongoing.
Occurrence of pyroclastic flows, tall eruption columns and extensive ashfall. Pyroclastic flows may sweep down along gullies and channels, especially along those fronting the low part(s) of the crater rim.
Additional danger areas may be identified as eruption progresses.
Danger to aircraft, by way of ash cloud encounter, depending on height of eruption column and/or wind drift.
Revised 25 January 2001
ALERT LEVEL MAIN CRITERIA INTERPRETATION/RECOMMENDATION
0
No Alert. Quiet.
All monitored parameters within background levels. No eruption in foreseeable future.
Entry in the 6-km radius Permanent Danger Zone (PDZ) is not advised because phreatic explosions and ash puffs may occur without precursors.
1
Abnormal Low level unrest.
Slight increase in seismicity.
Slight increase in SO2 gas output above the background level.
Very faint glow of the crater may occur but no conclusive evidence of magma ascent.
Phreatic explosion or ash puffs may occur. No eruption imminent.
Activity may be hydrothermal, magmatic or tectonic in origin.
No entry in the 6-km radius PDZ.
2
Increasing Unrest - Moderate unrest.
Low to moderate level of seismic activity.
Episodes of harmonic tremor.
Increasing SO2 flux.
Faint / intermittent crater glow.
Swelling of edifice may be detected.
Confirmed reports of decrease in flow of wells and springs during rainy season. Unrest probably of magmatic origin; could eventually lead to eruption.
6-km radius Danger Zone may be extended to 7 km in the sector where the crater rim is low.
3
Increased Tendency Towards Eruption - Relatively high unrest.
Volcanic quakes and tremor may become more frequent.
Further increase in SO2 flux.
Occurrence of rockfalls in summit area.
Vigorous steaming / sustained crater glow.
Persistent swelling of edifice. Magma is close to the crater.
If trend is one of increasing unrest, eruption is possible within weeks.
Extension of Danger Zone in the sector where the crater rim is low will be considered.
4
Hazardous Eruption
Imminent Intense unrest.
Persistent tremor, many "low frequency"-type earthquakes.
SO2 emission level may show sustained increase or abrupt decrease.
Intense crater glow. Incandescent lava fragments in the summit area. Hazardous eruption is possible within days.
Extension of Danger zone to 8 km or morein the sector where the crater rim is low will be recommended.
5
Hazardous Eruption
Hazardous eruption ongoing.
Occurrence of pyroclastic flows, tall eruption columns and extensive ashfall. Pyroclastic flows may sweep down along gullies and channels, especially along those fronting the low part(s) of the crater rim.
Additional danger areas may be identified as eruption progresses.
Danger to aircraft, by way of ash cloud encounter, depending on height of eruption column and/or wind drift.
Revised 25 January 2001
Thursday, October 29, 2009
Mayon Volcano Advisory
Mayon Volcano Advisory
28 October 2009
8:00 A.M.
This is to notify the public and concerned authorities on the current activity of Mayon Volcano.
At 5:32 AM today, one minor ash explosion occurred at the summit crater of Mayon Volcano (13.2576 N, 123.6856 E). This event lasted for about one minute. The explosion produced a brownish ash column that rose to a maximum height of about 600 meters above the crater and drifted to the northeast. For the past 24 hours, the seismic network recorded thirteen (13) volcanic earthquakes. Steam emission was at moderate level creeping downslope towards southwest. Sulfur Dioxide (SO2) emission rate was measured yesterday at 250 tonnes/day. Crater glow was not observed last night due to poor visibility.
The status of Mayon Volcano remains at Alert Level 2. This means a state of unrest which could lead to more ash explosion or eventually to hazardous magmatic eruption. Thus PHIVOLCS strongly 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 are off-limits due to the threat from sudden explosions and rockfalls from the upper slope. Active river channels and those areas perennially identified as lahar prone in the southeast sector should also be avoided especially during bad weather condition or when there is heavy and prolonged rainfall.
Any new development will be posted and relayed immediately to all concerned authorities.
28 October 2009
8:00 A.M.
This is to notify the public and concerned authorities on the current activity of Mayon Volcano.
At 5:32 AM today, one minor ash explosion occurred at the summit crater of Mayon Volcano (13.2576 N, 123.6856 E). This event lasted for about one minute. The explosion produced a brownish ash column that rose to a maximum height of about 600 meters above the crater and drifted to the northeast. For the past 24 hours, the seismic network recorded thirteen (13) volcanic earthquakes. Steam emission was at moderate level creeping downslope towards southwest. Sulfur Dioxide (SO2) emission rate was measured yesterday at 250 tonnes/day. Crater glow was not observed last night due to poor visibility.
The status of Mayon Volcano remains at Alert Level 2. This means a state of unrest which could lead to more ash explosion or eventually to hazardous magmatic eruption. Thus PHIVOLCS strongly 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 are off-limits due to the threat from sudden explosions and rockfalls from the upper slope. Active river channels and those areas perennially identified as lahar prone in the southeast sector should also be avoided especially during bad weather condition or when there is heavy and prolonged rainfall.
Any new development will be posted and relayed immediately to all concerned authorities.
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