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ancient and modero volcanic activi–
ty.
Scientists have long wondered
how volcanic eruptions affect cl i–
mate and weather. In 1815, the
most powerful volcanic erupt ion in
recorded human history took place.
Tambora volcano in what is now
Indonesia exploded. More than 36
cubic miles ( 1.7 million tons) of
debris were scattered over one mil–
lion sq ua re miles.
So much debris filled the strato–
sphere that it created a huge filler
that rcduced temperatures by as
much as 2 degrees Fahrenheit for
more than a year.
It
is believed that
this caused the record low tempera–
tu res that produced what was
called "the year without summer."
Until now, however, evidence was
more circumstantial than conclu–
sive.
But studies conducted at El Chi–
chón volcano in Mexico after its
1982 eruption have given scientists
evidcnce to suggest that volcanic
eruptions
can
and
do
affect weather
conditions.
In the case of El Chichón , it
was found that after its eruption,
temperatures of the equatorial
st ratosphe re rose by 4 degrees
Celsius, causing the warmest tcm–
perature reading si nce strato–
sphcric temperatures were first
recorded in 1958.
Many scientists conclude that by
altering these temperatures so
much, the El Chichón eruption
contributed to the intense El Niño
phenomenon of 1982-83. (See the
Janu ary 1984
Scientific Ameri–
can.)
Nevertheless, in spi te of these
new discoveries, a comprehensive
picture of volcanoes and their
effects remains elusive.
What is known is that many vol–
canoes are now about due for erup–
tions. According to a 1983 report
by the U.S. Geological Survey,
May 1984
Mount St. Helens may only be a
preview of things to come for the
Western United States.
What would have happened had
a Mount St. Helens erupted near a
large city?
lt
is a frightening
thought, but, as the report sug–
gests, not one that is beyond the
realm of possibi lity. What is puz–
zling to many scienti sts is that
though the earth theoretically is
cooling off, volcanic activity is
increasing,
not decreasi ng.
A preliminary list in this report
noted 35 volcanoes in the Western
United States that are now consid–
ered likely to erupt sometime in the
future. T he Mono-Jnyo Craters,
ncar San Francisco, California, are
considered the next most likely to
erupt. Then come Lassen Peak and
Mount Shasta, also in California.
Others on the list include Mount
Rainier , Mount Baker in Washing–
ton state and Mount Hood in Ore–
gon-all much nearer to large pop–
ulat ion centers than Mount St.
Helens.
Heeding the Warn ings
In the last five centuries, more than
200,000 people have lost their lives
because of volcanic eruptions.
"Such catastrophes [loss of life]
needn't recur. A volcanic eruption
is preceded by ample warnings of
tremors or escaping steam," noted
one scientist with the U.S. Geolog–
ical Survey. This is most assuredly
true, but hi s tory- modern and
ancient- has proveo that people
do
fail to heed warnings.
Whether out o f c uri os ity or
inditference to the rcpeated warn–
ings of civil a uthorities, humans do
become fataJities- witness Mount
St. Helens (65 dead) , Mexico's El
Chichón ( 187 dead- unofficially
thought to be five times that high)
and l ndonesia's Galungg ung on
populous Java (30 dead) . H istory
records many such tragedies.
J
In 1883, approximately 36,000
5
lost their lives in a 100-foot tidal
t
wave caused by the spectacular ...
eruption of Krakatoa in Indonesia.
j
So powerful was the explosion that
~
it was heard 3,000 miles away! The
effects of the tidal wave that
ensued were seen as far away as the
English Channel.
In 1783, one fifth of the popula–
tion of Tceland starved to death
from the loss of almost haJf of that
island nation's livestock to the poi–
sonous gases from Mount Laki 's
massive eruption and lava flow.
Examples for Us Today
For weeks the stench of sulfur cor–
rupted the ai r in the city of Saint–
Pierre, Martinique-sometimes
called the París of the Caribbean. lt
was indeed a charming city, with
brightly co lored homes wi th
wrought iron trim. The landscape,
however, was dominated by an
active volcano, Mount Pelée. But
besides the volcano there was
another undesirable side to this
city. Saint-Pier re, it seems, was
also known as
the lustiest port in
the Caribbean!
On May 8, 1902, the 34,000
inbabitants of Saint-Pierre were
slaughtered in only three minutes
when Mount Pelée erupted. The
lateral blast of this volcano sent a
raging tide of superheated gases
(about 1,800 degrees Fahren heit-
1,000 Celsius) toward the doomcd
city at a speed of 300 miles an
hour!
Probably the most famous vol–
canic catast rophe in history was the
A.D. 79 eruption of Mount Vesu–
vius that destroyed Pompeii , Her–
culaneum and severa! other Cam–
panian cities.
These were weaJthy ci ties on the
Gulf of Naples j ust southeast of the
modcrn-day c ity of Naples. Pom-
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