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Eruption of 1995
Eruption of 1995:
Weak earthquakes were felt starting March 25th, 1995.
On April 2nd the earthquakes became stronger and more
frequent, and were felt by the people surrounding Fogo.
On the night of April 1st a red glow was emitted from
the volcano and the eruptive vents were noticeably open.
The eruption began on April 3rd with a fissure eruption
followed by some lava flow. The volcano then sent
of bursts of gases followed by large blocks of rock, and
eventually a large lava flow. Fine dark ash was
falling and an eruption cloud that covered 2,500 meters
was formed around the volcano. People near the
volcano described the volcano as sounding like an "old
stove" and observed "mushroom-shaped ash" coming from
the volcano. There was one long fissure vent that
produced "lava fountains" and three smaller vents that
produced fine dark ash, small pahoe lavas, and large
plastic bombs that were thrown up to 500 meters from the
volcano. Brown pyroclastic material was produced
as more vents opened until the morning of April 4th,
when the volcano continued to experience strong effusive
activity but the amount of pyroclastic fragments
produced decreased. The lava flowed at a fairly
constant rate until April 7th when the lava began to
flow even faster and by April 10th the seismic activity
had increased significantly and earthquakes of higher
intensities began to occur (Mercalli intensity 3-4).
On the morning of April 10th Fogo would have been
considered a Strombolian eruption, but by the afternoon
it looked more like an Hawaiian eruption and was
producing fire fountains (see picture below). A cone was forming that
continued to grow as the fire fountains continued
through April 16th. By April 17th there was an
even higher tremor amplitude and the volcano produced
louder bursts. Through early May the lava flow was
slightly slower and there were some calm periods, but
not until May 17th did the lava stop flowing. On
May 17th clouds of gas and dust surrounded Fogo and a
strong Sulfur smell was emitted. This continues
until May 28th, when the eruption finally ended.¹
The eruption of 1995 destroyed
1.6 square miles of productive farmland and caused the
evacuation of 5,000 people.²²
A fire fountain during Fogo's eruption.²
Dust and smoke being produced during Fogo's eruption.³
VEI: 2
Fogo has a VEI of 2 because it is explosive and
produces a large, but not enormous, amount of Tephra.
Fogo has periods when it seems characteristically
strombolian, but then it also has some lava fountains
which are very characteristic of a Hawaiian volcano,
which are very non-explosive. During different
periods of Fogo's eruption it could be categorized under
a variety of different VEI ratings, but overall it
probably falls best under the level 2 category of
volcanoes.
Mercalli Eruption Style Name: Strombolian.
Fogo is a Strombolian style volcano because the eruption
is noisy, it produces some fragments of plastic lava and
dusty tephra, it produces low viscosity magmas, and a
cinder cone is formed.
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