Linggo, Pebrero 5, 2012

Mayon Volcano, also known as Mount Mayon, is an active volcano in the province of Albay, on the island of Luzon in the Philippines. Renowned as the "perfect cone" because of its almost symmetric conical shape, Mayon forms the northern boundary of Legazpi City, the largest city in terms of population in the Bicol Region. The mountain is a national park and a protected landscape in the country proclaimed as as Mayon Volcano Natural Park in the year 2000.[3]
Local folklore refers to the volcano as Bulkang Magayon (Bikol: 'Beautiful Volcano'), after the legendary heroine Daragang
Mayon Volcano is the main landmark of Albay Province, Philippines, rising 2,462 metres (8,077 ft) from the shores of the Gulf of Albay about 10 kilometres (6.2 mi) away.[5][6] The volcano is geographically shared by the cities and municipalities of Legazpi City, Daraga, Camalig, Guinobatan, Ligao City, Tabaco City, Malilipot, and Santo Domingo (clockwise from Legazpi) which divide the cone like slices of a pie when viewed from above.

[] Geomorphology

Mayon is a classic stratovolcano type of volcano capped by a small central summit crater. The cone is considered to be the world's most perfectly-formed volcano for its symmetry,[6] which was formed through layers of pyroclastic and lava flows from past eruptions and erosion. The upper slopes of the basaltic-andesitic volcano are steep averaging 35–40 degrees.
Like other volcanoes located around the Pacific Ocean, Mayon is part of the Pacific Ring of Fire. It is located on the eastern side of Luzon, near the Philippine Trench which is the convergent boundary where the Philippine Sea Plate is driven under the Philippine Mobile Belt. When a continental plate or belt of continental fragments meets an oceanic plate, the lighter continental material overrides the oceanic plate, forcing it down into the Earth's mantle. Magma may be forced through weaknesses in the continental crust caused by the collision of the tectonic plates. One such exit point is Mayon.

[] Recorded eruptions

Mayon is the most active volcano in the Philippines having erupted over 48 times in the past 400 years.[7] The first record of a major eruption was witnessed in February 1616 by Dutch explorer Joris van Spilbergen who recorded it on his log in his circumnavigation trip around the world.[8]

An old photograph of the Cagsawa ruins with the facade still standing. The church was largely destroyed during the 1814 eruption of Mayon.
The most destructive eruption of Mayon occurred on February 1, 1814. Lava flowed but not as much compared to the 1766 eruption. Instead, the volcano was belching dark ash and eventually bombarding the town with tephra that buried the town of Cagsawa. Trees were burned; rivers were certainly damaged. Proximate areas were also devastated by the eruption with ash accumulating to 9 m (30 ft) in depth. 2,200 Albay locals perished in what is considered to be the most lethal eruption in Mayon's history.[6] Estimates by PHIVOLCS and list the casualties at about 1200. The eruption is believed to have contributed to the accumulation of atmospheric ash,[citation needed] capped off by the catastrophic eruption of Mount Tambora in 1815, that led to the Year Without a Summer in 1816.

Mount Mayon in eruption on July 21, 1928.
Mayon Volcano's longest uninterrupted eruption occurred on June 23, 1897 which lasted for seven days of raining fire. Lava once again flowed down to civilization. Seven miles eastward, the village of Bacacay was buried 15 m (49 ft) beneath the lava. In Libon 100 people were declared dead—incinerated by steam and falling debris or hot rocks. Other villages like San Roque, Misericordia and Santo Niño became deathtraps. Ash was carried in black clouds as far as 160 km (100 mi) from the catastrophic event, which killed more than 400 people.[6]
Samuel Kneeland, a professor and a geologist had observed the volcanic activity five months before the eruption:
At night the scene was truly magnificent and unique. At the date of my visit the volcano had poured out...a stream of lava on the Legaspi side from the very summit. The viscid mass bubbled quietly but grandly, and overran the border of the crater, descending several hundred feet in a glowing wave, like red-hot iron. Gradually, fading as the upper surface cooled, it changed to a thousand sparkling rills among the crevices, and, as it passed beyond the line of complete vision behind the woods near the base, the fires twinkled like stars, or the scintillions of a dying conflagration. More than half of the mountain height was thus illuminated.[9]

Mayon Volcano on September 23, 1984
No casualties were recorded from the 1984 eruption after more than 73,000 people were evacuated from the danger zones as recommended by PHIVOLCS scientists.[10] But in 1993, pyroclastic flows killed 77 people, mainly farmers, during the eruption.
Its 48th eruption was a quiet effusion of lava on July 14, 2006,[11] which was aggravated when a lahar caused by the rains of Typhoon Durian followed on November 30, 2006. The small activities from 2003 and 2004 are considered as precursors to the 2006 eruption. The small summit explosion which occurred on August 10, 2008 is considered as part of the ongoing activity since 2006.[7] Starting in January 2011, the volcano is weakly erupting and may be building up to a larger hazardous eruption.

[edit] 2006 eruption

Mayon erupted again from July to October 2006, with no apparent loss of life during the actual eruption period.
  • August 7, 2006: The Philippine government ordered the evacuation of about 20,000 people living near the volcano, stating that an eruption was feared soon.[12] Volcanologists have detected 21 low-frequency volcanic earthquakes since early Sunday morning.[13]
  • August 8, 2006: The government expected to move some 34,276 people to 31 state-run shelters and warned that the mountain could explode at any time.[14][15]

Mayon Volcano in satellite image.
  • August 9, 2006: Volcanologists warned that Mount Mayon could explode at any time but that the gravitational pull of a full moon could provide the final push. A full moon coincided with at least three of Mayon’s nearly 50 explosions over the last four centuries, including the two most recent in 2000 and 2001. Nearly 40,000 people have been moved from an 8 km (5 mi) danger zone on the southeast flank of the volcano, which has been quaking and spitting plumes of ash since July.[16]
  • August 10, 2006: Scientists in the Philippines renewed warnings of a major explosion at the Mount Mayon volcano, describing a sudden period of quiet as "ominous". A drop in gas emissions and earthquakes sparked fears that the crater had plugged itself, increasing the likelihood of an explosive eruption.[17]
  • August 11, 2006: Scientists said ground surveys showed Mayon was still "swollen" and registered a high number of volcanic earthquakes, emitted large amounts of sulfur dioxide gas and continued to eject lava down its slope nearly four weeks after it came to life in a "quiet" eruption on July 14.[18]
Phivolcs maintained threat level at Alert Level 4 for the next month because of the continued extrusion of lava, ash explosions, steam and smoke plumes, seismic activity, and threat of further eruption.
  • September 11, 2006 Phivolcs downgraded threat level to Alert Level 3. "After the ash explosion of September 1, a general decline in the overall activity of Mayon has been established. The decrease in key parameters such as seismicity, gas (Sulfur Dioxide) emission rates and ground inflation all indicate a waning condition. The slowdown in the eruptive activity is also evident from the decrease in intensity of crater glow and the diminishing volume of lava being extruded from the summit".[19]
  • October 3, 2006 Phivolcs downgraded threat level to Alert Level 2. "All monitored key parameters such as earthquake levels, ground deformation and gas outputs further declined. In addition, lava extrusion apparently ceased on October 1, 2006 as reported by Ligñon Hill Observatory. The above observations indicate the absence of an intruding new mass of magma."[20]
  • October 25, 2006 Phivolcs downgraded threat level to Alert Level 1 (no hazardous eruption imminent).[21]

[] 2008 eruption

On August 10, 2008, a small summit explosion ejected ash 200 metres (660 ft) above the summit, with the ash drifting east northeast. In the weeks prior to the eruption,[22] there was a visible glow within the crater and increased seismicity.[23]

[] 2009–2010 eruption

On July 10, 2009, PHIVOLCS raised the status from Alert Level 1 (low level unrest) to Alert Level 2 (moderate unrest) because the number of recorded low frequency volcanic earthquakes rose to the same level when a phreatic explosion occurred last August 2008.[24][25]
At 5:32 am Wednesday October 28, 2009, a minor ash explosion lasting for about one minute occurred in the summit crater. A brown ash column rose about 600 metres (2,000 ft) above the crater and drifted toward the northeast. In the prior 24 hours, 13 volcanic earthquakes were recorded. Steam emission was at moderate level, creeping downslope toward the southwest. PHIVOLCS maintained the Alert Status at Level 2, but later warned that with the approach of tropical cyclone international codename Mirinae the danger of lahars and possible crater wall collapse will greatly increase and all specified precautions should be taken.[26]
At 1:58 am Wednesday November 11, 2009, a minor ash explosion occurred at the summit crater lasting for about three minutes. This was recorded by the seismic network as an explosion type earthquake with rumbling sounds. Incandescent rock fragments at the upper slope were observed in nearby barangays. Ash column was not observed because of cloud cover. After dawn, field investigation showed ashfall had drifted southwest of the volcano. In the 24 hour period, the seismic network recorded 20 volcanic earthquakes. Alert Status was kept at Level 2 indicating the current state of unrest could lead to more ash explosion or eventually to hazardous magmatic eruption.[27]

Mayon Volcano with ash explosion at dawn on December 18, 2009
At 8 pm on Monday December 14, 2009, as a result of 83 volcanic quakes in the preceding 24 hours[28] and increased sulphur dioxide emissions, Phivolcs raised the Alert status to Level 3.[29]
Early in the morning of Tuesday December 15, 2009, a moderate ash explosion occurred at the summit crater and "quiet extrusion of lava" resulted in flows down to about 500 metres from the summit of Mayon.[30] By Tuesday night Albay Province authorities were reported to have moved about 20,000 residents out of the eight kilometre danger zone and into local evacuation centres. About 50,000 people were said to live within the eight kilometer zone.[31][32]
On December 17, 2009, there were five ash ejections with one reaching 500 meters above the summit, sulphur dioxide emission increased to 2,758 tonnes per 24 hours, lava flows reached down to 1500 metres below the summit, and incandescent fragments from the lava pile continuously rolling down Bonga Gully reached a distance of 3 to 4 km below the summit. By midday December 17, a total of 33,833 people from 7,103 families had been evacuated, 72 percent of the total number of people that needed to be evacuated, Albay Governor Joey Salceda was reported to have said.[33]
On December 20, 2009, PHIVOLCS raised Mayon's status level to alert level 4 because of an increasing lava flow in the southern portion of the volcano and an increase in sulphur dioxide emission to 750 tonnes per day. As well, almost 460 earthquakes in the volcano were monitored everyday. In the border of danger zone, rumbling sounds like thunder were also heard. Over 9,000 families (44,394 people) were evacuated by the Philippine government from the base of the volcano.[34] No civilian was permitted within the 8 kilometer danger zone, which has been cordoned off by the Philippine military, who were actively patrolling within the danger zone to enforce the "no-go" rule and to ensure no damage or loss of property of those evacuated.[35]

Mayon Volcano in eruption on December 29, 2009.
Alert level 4 was maintained as the volcano remained restive through the month of December, prompting affected residents to spend Christmas and the New Year in evacuation centers.[36] On December 25, sulfur dioxide emissions peaked at 8,993 tons per day.[37][38] On December 28, PHIVOLCS director Renato Solidum commented on the status of the volcano, "You might think it is taking a break but the volcano is still swelling."[35] On the next day December 29, a civil aviation warning for the airspace near the summit was included in the volcano bulletins.[39] The ejected volcanic material since the start of the eruption was estimated to have been between 20 million to 23 million cubic meters of rocks and volcanic debris, compared to 50 million to 60 million cubic meters in past eruptions.[40]
On January 2, 2010, PHIVOLCS lowered the alert level of the volcano from level 4 to level 3, citing decreasing activity observed in the past four days.[41] The state agency noted the following observations as a trend of decreasing activity: absence of ash ejections and relative weakness of steam emissions, majority of earthquakes caused by rockfalls and rolling fragments, and gradual decrease in sulfur dioxide emissions from a maximum of 8,993 tons per day to 2,621 tons per day.[38] 7,218 families within the seven-kilometer to eight-kilometer danger zones were allowed to return to their homes, while 2,728 families who live in the four-kilometer to six-kilometer danger zones would have to stay in the evacuation centers pending the PHIVOLCS decision to further lower the alert level.[42]
On January 13, 2010, PHIVOLCS reduced the alert level from 3 to 2, saying that this indicated a further reduction in the likelihood of hazardous eruption.[43]

[] Government response


Map showing major volcanoes of the Philippines
Albay governor Joey Salceda declared the disaster zone an 'open city' area to encourage aid from external groups. Potential donors of relief goods were not required to secure clearance from the Provincial Disaster Coordinating Council, but were able to directly coordinate with support groups at the local government level.[44]
The restiveness of the volcano also stimulated the tourism industry of the province. Up to 2,400 tourists per day have arrived in the area since the volcano started erupting on December 14, filling local hotels, compared to about a more modest average of 200 in the days prior. However it was reported that some tourists lured by local "guides" might be ignoring government warnings not to venture into the 8-kilometre (5.0 mi) danger zone. "It's a big problem. I think the first violation of the zero casualty (record) will be a dead tourist," said Salceda.[45]
Speaking about thrill-seekers finding their way in to the area, Salceda warned, "At the moment of the eruption, the local guides will have better chance of getting out. The hapless tourist will be left behind."[45]

[] International response

Following the declaration of alert level 3 for the volcano, the United States issued an advisory cautioning its nationals from traveling to Mayon. Canada and the United Kingdom also posted advisories discouraging their nationals from visiting the volcano.[46]
The United States government has committed $100,000 in financial aid for the evacuees of Mayon Volcano. In cooperation with the Philippine government the assistance will be delivered through the Philippine National Red Cross and other NGOs by USAID.[47]
The Albay provincial government has ordered the local military to add more checkpoints, place roadblocks and arrest tourists caught traveling inside the eight-kilometer danger zone.[48]
Power and water supply were cut off within the danger zone to further discourage residents from returning. The Commission on Human Rights has allowed the use of emergency measures and has given the authorities clearance to forcibly evacuate residents who refuse to leave.[49]
When the alert level around the volcano was lowered from alert level 4 to alert level 3 on January 2, 2010, the Albay provincial government ordered a decampment of some 47,000 displaced residents from the evacuation centers.[50] Power and water supply in the danger zones were restored.[36] Military vehicles were used to transport the evacuees back to their homes, while food supplies and temporary employment through the Department of Social Welfare and Development (DSWD) were provided to the heads of each family.[50][51] As of January 3, 2010, the National Disaster Coordinating Council reported the overall cost of humanitarian aid and other assistance provided by the government and non-government organizations (NGOs) has reached over 61 million pesos since the start of the eruption.[52]
The United Nations World Food Programme (UN-WFP) has delivered 20 tons of high energy biscuits to the evacuees to complement supplies provided by the DSWD, with more to be allocated from emergency food stocks intended for relief from the effects of the 2009 Pacific typhoon season.[53] When the alert level was downgraded to level 3 on January 2, 2010, UN-WFP provided three days worth of food for evacuees returning to their homes who will continue to receive supplies already set aside for them.[41]

[] Devastating lahars following eruptions and typhoons


The church tower is what remains of the Cagsawa Church, which was buried by the 1814 eruption of Mayon Volcano. It withstood the damage done by Typhoon Durian in 2006.
Following the eruption of 2006, on November 30 of that year, strong rainfall which accompanied Typhoon Durian produced lahars from the volcanic ash and boulders of the last eruption killing at least 1,266 people. The precise figure may never be known since many people were buried under the mudslides.[4] A large portion of the village of Padang (an outer suburb of Legazpi City) was covered in mud up to the houses' roofs.[54][55] Students from Aquinas University in Barangay Rawis, also in Legazpi, were among those killed as mudslides engulfed their dormitory. Central Legazpi escaped the mudslide but suffered from severe flooding and power cuts.
Parts of the town of Daraga were also devastated, including the Cagsawa area, where the ruins from the eruption of 1814 were partially buried once again. Large areas of Guinobatan, Albay were destroyed, particularly Barangay Maipon.
Similar post-eruption lahar occurred in October 1766, months after the July eruption of that year. The heavy rainfall also accompanying a violent typhoon carried down disintegrated fragmental ejecta, burying plantations and whole villages. In 1825, the event was repeated in Cagsawa killing 1,500 people.[56]

[] Monitoring Mayon

Mayon Volcano is the most active volcano in the Philippines, and its activity is regularly monitored by PHIVOLCS from their provincial headquarters on Lignon Hill, about 10 kilometres (6.2 mi) SSE from the summit.
Three telemetric units are installed on Mayon's slopes, which send information to the seven seismometers in different locations around the volcano. These instruments relay data to the Lignon Hill observatory and the PHIVOLCS central headquarters on the University of the Philippines Diliman campus.
PHIVOLCS also deploys electronic distance meters (EDMs), precise leveling benchmarks, and portable fly spectrometers to monitor the volcano's daily activity.
ayon Volcano is the main landmark of Albay Province, Philippines, rising 2,462 metres (8,077 ft) from the shores of the Gulf of Albay
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