Mayon Volcano

From Wikipedia

Mayon Volcano found in the Philippines. It is located in the province of Albay in the Bicol Region. It has an almost perfectly-shaped cone which is considered by many people to be more beautiful than Mount Fuji in Japan. A few kilometers to the south of the volcano is Legazpi City.

Mayon Volcano is classified by volcanologists as a stratovolcano (composite volcano). Its symmetric cone was formed through alternate pyroclastic and lava flows. Mayon is the most active volcano in the country, having erupted around 50 times for the past 400 years.

The most destructive eruption of Mayon occurred on February 1, 1814. Lava flows buried the town of Cagsawa and 1,200 people perished. Only the belltower of the town church remained. It is located between the Eurasian and the Philippine Plate and is a destructive plate boundary. Where a continental plate meets an oceanic plate it forces the denser oceanic plate down, pushing magma up.



From Phivolcs

PHYSICAL FEATURES
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

GEOLOGICAL FEATURES
Rock Type: Basalt to Olivine-bearing Pyroxene Andesite
Tectonic Setting: Bicol Volcanic Chain

VOLCANIC ACTIVITY
Number of Historical Eruptions: 47
Latest Eruption/Activity:
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)

Eruption Type:
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)

Precursors 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 emission 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

VOLCANIC HAZARDS
Type of Hazards:
1. Airfall tephra
2. Lava flows
3. Pyroclastic flows
4. Lahars
Permanent Danger Zone: six (6) km radius from the summit

MONITORING ACTIVITY
Volcano Observatory: Lignon Hill Observatory (LHO) - 12 km SSE of the summit (123°43.56’ E, 13°09.64’N)

Monitoring Methods:
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

Monitoring Stations
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 Palanog)
· Permanent Electronic tilt: Upper Anoling, Buang and Mayon Rest House
· Mobile electronic tilt: Upper Anoling, Lower Anoling and Upper MRHO