NAME OF VOLCANO: MAYON
LOCATION: Albay, 300 km southeast of Manila
Elevation: 2.46 km
Base Diameter: 20 km
Base Circumference: 62.8 km (reckoned from 10-km radius) encompassing the towns of Camalig, Malilipot and Sto. Domingo
Area: 314.1 km2 (estimated from 62.8 km base circumference)
Type of Volcano: Stratovolcano
Adjacent Volcanic Edifice: Mt. Malinao, Lignon Hill and Balong Gloria Hill
Rock Type: Basalt to Olivine-bearing Pyroxene Andesite
Tectonic Setting: Bicol Volcanic Chain
Number of Historical Eruptions: 47
01 June 2001 (mild eruption – quiet effusion of lava)
23 June 2001 (Strombolian-explosive but not hazardous)
24 June 2001 (Vulcanian-hazardous eruption )
26 July 2001 (Vulcanian-hazardous eruption)
1. Strombolian (e.g.. 1978, 1st phase of 1984 eruption)
2. Vulcanian (e.g. 1st phase of 1968 eruption, 2nd phase of 1984 eruption)
3. Plinian (e.g. 1814)
Signs to Eruptions:
1. Increase in seismicity level (Background: 0-10 volcanic quakes per day)
2. Ground tilt due to magma intrusion.
3. Change in color of steam production from white to gray due to entrained ash
4. Increase in the volume of steam emission
5. Crater glow due to presence of magma at or near the crater.
6. Rumbling sounds due to gas explosions, wall fracturing, landslides
Type of Hazards:
1. Airfall tephra
2. Lava flows
3. Pyroclastic flows
Permanent Danger Zone: six (6) km radius from the summit
Volcano Observatory: Lignon Hill Observatory (LHO) - 12 km SSE of the summit (123?43.56’ E, 13?09.64’N)
1. Seismic monitoring (number of volcanic quakes and tremors)
2. Ground deformation (precise leveling, electronic tilt, GPS)
3. Visual observations
4. Sulfur dioxide emission rate (by COSPEC)
5. Water well monitoring
A - Seismic Network
• Digital Permanent: Lignon Hill Observatory, Upper Anoling, Upper Sta. Misericordia and Mayon
Rest House with repeater sites at Mt. Bariw, Upper Sto. Domingo and Tabaco
• Digital Mobile: Upper Mayon Rest House, Upper Masarawag and Lignon Hill Observatory with repeater sites at Ligao and Camalig
• Analog: Upper Anoling
B - Ground Deformation
• Precise leveling lines: Buang Junction to Mayon Rest House (20 benchmarks); Lidong (13 benchmarks) and Anoling
• GPS stations: Legazpi (Lignon Hill), Sto. Domingo (San Andres), Malilipot (Calbayog),
Tabaco (MRH), Malinao, Ligao (Nabonton) and Camalig (Upper Anoling, Tinago, and
• Permanent Electronic tilt: Upper Anoling, Buang and Mayon Rest House
• Mobile electronic tilt: Upper Anoling, Lower Anoling and Upper MRHO
MAYON VOLCANO ALERT SIGNS
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.
|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.
|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.
|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.
|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.
|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.
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