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Roger Weller, geology instructor
by Jeroel A. Padilla
Mayon Volcano: The Perfect Cone
(Fig. 1) The Mayon Volcano
One of the most ever visited places in the Philippines is the Mayon
Volcano – also called as Mount Mayon, considered as the greatest attraction for
tourists and travelers through its awesome structure and vista. Along with other
volcanoes located in other areas such as Mt. Taal, Mt. Pinatubo, and Mt. Bulusan,
Mayon Volcano is also an active volcano and could erupt at any time. It,
however, still attracts the attention of every people because of its perfect
Located in the Bicol Region, on the island of Luzon, in the
Philippines, “Mayon Volcano reaches 2,460 meters and is the central feature of
the Albay Province, of which Legazpi City is the capital, about 300-km southeast
of Manila” (shown in fig. 1) (8). “It has a base of 80 miles (130 km) in
circumference and rises to 7,943 feet (2,421 m) from the shores of Albay Gulf”
(shown in figure 2) (7). Moreover, the Mayon volcano, together with other
volcanoes in the Philippine islands, is also included in the pacific ring of
fire, the belt where most threatening earthquakes and volcanic eruptions are
violently taking place. Therefore, the volcano, up to this point, is still
having its volcanic activity and could create a massive eruption at any time.
The Bicolanos who live near the volcano also have a legend about it, and they called it as the Legend of Magayon. “There once lived a very beautiful native princess who had an uncle named Magayon. He was so possessive of his niece that no man dared to challenge his wrath by courting the favors of the young maiden. One day, however, a brave and virile warrior was so smitten by the princess that he threw all cares to the wind, clambered up through the window of the royal chamber and enticed the girl to elope with him. With Magayon at their heels, the couple prayed to the gods for assistance. Suddenly from out of nowhere, a landslide buried the raging uncle alive. Local folks now claim that it is Magayon's anger bursting forth in the form of eruptions (1).” The legend only shows the people’s appreciation for having a captivating view of Mayon Volcano in spite of its frightening effect in their vicinity.
2 Mayon’s location (wider view) (8)
Fig. 3 Mayon’s location (closer view) (6)
Mayon Volcano is an
active strato-volcano. Its conical structure is made up of alternating layers of
ash and lava during the period when Mayon volcano has been erupting for millions
of years. The process took for a long time until the construction of the volcano
has formed into a conical shape. “The structurally simple volcano has steep
upper slopes that average 35-40 degrees and is capped by a small summit crater
(1)”. It usually spews out pyroclastic materials, fiery fragments that are being
tossed out from the volcano. The rock type that can be found in the volcano is
usually Basalt to Olivine – bearing Pyroxene Andesite (3). During the explosion,
massive lava flows and mud flows are descended to the lower plains of the
volcano in which destroys huge amount of crops and food resources. “The
historical eruptions of this basaltic-andesitic volcano date back to 1616 and
range from Strombolian to basaltic Plinian, with cyclical activity beginning
with basaltic eruptions, followed by longer term andesitic lava flows (2).” The
permanent danger zone is six kilometer radius from the summit (3).
Institute of Volcanology and Seismology or (PHIVOLCS), a
service institute of the Department of Science and Technology (DOST) that is
principally mandated to mitigate disasters that may arise from volcanic
eruptions, earthquakes, tsunami and other related geotectonic phenomena (3), has
been observing the Mayon’s behavior and activity for several years. They
are informing the people near the volcano to get prepared in case of unexpected
eruption of Mt. Mayon. The institute even has its volcano alert levels that are
used as their basis for tracking the Mayon’s volcanic activity.
Fig. 4 shows the volcanic activity of Mayon during the 1993 eruption (1).
MAYON VOLCANO ALERT LEVELS (3)
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.
No eruption imminent.
Activity may be hydrothermal, magmatic or tectonic in origin.
No entry in the 6-km radius PDZ.
Low to moderate level of seismic activity.
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.
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.
Persistent tremor, many "low frequency"-type earthquakes.
Hazardous eruption is possible within days.
Extension of Danger zone to 8 km or more in the sector where the crater rim is low will be recommended.
Hazardous eruption ongoing.
Occurrence of pyroclastic flows, tall eruption columns and extensive ash fall.
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 drifts.
Revised 25 January 2001
Fig. 5 (See the video of Mayon Volcano Eruption 2009 (http://www.youtube.com/watch?v=qe50AIJ7g9M)
Since 1619, Mount Mayon has a total number of 48 historical eruptions, and the recent explosion held on 2009, where the alert level reached up to level 4, resulting in a vast evacuation of more than 40,000 people who live near the volcano. “The Mayon Volcano also had its major eruption on 1814, which killed more than 1,200 people and destroyed several towns and houses” (4). Another eruption occurred in 1993 which all started with an unexpected explosion. The pyroclastic flows of the volcano killed 68 people and 60,000 people were evacuated in a safe area (1).
Fig. 6 shows the complete image of the Cagsawa church before it had been buried with lave flows during the 1814 eruption of Mt. Mayon (6).
(Fig. 7) In the aftermath of the 1814 eruption, the photo shows the current view of the church in which the belfry is the only thing remaining (6).