Geologic Background:
The beautifully symmetrical Mayon volcano, which
rises to 2,462 m above the Albay Gulf, is the
Philippines' most active volcano. The structurally simple
volcano has steep upper slopes that average 35-40 degrees
and is capped by a small summit crater breached to the
southeast.
Historic Activity:
- The historical eruptions of this basaltic-andesitic
volcano date back to 1616. Eruptions have ranged from
Strombolian to basaltic Plinian. Eruptions, which have
occurred predominately from the central conduit, have
vented lava flows that traveled far down the flanks.
Pyroclastic flows and mudflows have commonly swept down
many of the ravines that radiate from the summit and have
often devastated populated lowland areas.
- Mayon's last vigorous eruption, in September 1984,
generated large tephra columns, pyroclastic flows, lava
flows, and destructive lahars, forcing the evacuation of
about 73,000 people. Crater glow was first observed on
Aug 15th, 1988. New areas of steaming in the crater were
noted in September thru November.
Recent Activity:
- Mayon erupted unexpectedly with an explosion on Feb.
2, 1993, and additional emissions on the 3rd, 6th, and
12th. The initial eruption generated a pyroclastic flow
that travelled 6 km SSE down the Bonga gully and spread
out over most of the fan built by 1984 pyroclastic flows,
killing at least 68 people and prompting the evacuation
of over 60,000 others. A cauliflower-shaped cloud rose
4.5 km above the summit. During Feb. activity has
consisted principally of slow lava extrusion, occasional
ash puffs, explosions, and small pyroclastic flows.
- Lava fountaining began on March 21 after almost 2
months of intermittent precursors, including the small,
but deadly, phreatomagmatic eruption on Feb. 2. Following
the Feb. 2 eruption, sluggish and intermittent production
of lava continued until March 19 when its extrusion rate
increased. Lava fountaining produced a small cone at the
head of Bonga gully and a flow extended about 5 km from
the summit by April 1, 1993. Lava fountains ceased by
April 2. On April 9 a dirty-white steam plume rose above
the crater and a faint glow was observed at night.
- From Aug. 23 to 25, 1995, moderate to intense glow
from the crater of Mayon was observed. Moderate steam
emissions preceded the observation of glow.
- On June 22, 1999, Mayon emmitted an ash column that
rose 7 to 10 km above the vent.
- Dome growth began on Feb 12, 2000. Several large
explosive eruptions between Feb. 28 to March 1.
Decreasing activity through June. Mild activity from July
to December.
- Activity increased in Jan 2001 with new dome growth.
Activity increased more in July with pyroclastic
flows.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 9, No. 8 to V. 13,
No. 11)
- Global Volcanism Network (V. 18, No. 1 to V. 26, No.
8).
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