JULY/AUGUST 2019. DISCOVER 11
IT WAS 1975 on the Caribbean island
of Basse-Terre, part of Guadeloupe.
Beyond a green stretch of jungle, the
volcano La Soufrière de Guadeloupe
loomed. The island’s capital, also called
Basse-Terre, lay nestled between the
ocean and the towering peak, which
hadn’t had a major eruption since
around 1530. But that July, La Soufrière
began showing signs of life.
Debate ensued among seismologists
over the chances of a major eruption;
some saw evidence that molten magma
below the Earth’s crust was rising. By
November, authorities were scrambling
to craft an emergency plan for the city
and the surrounding area, then home to
roughly 75,000 people. In August of the
following year, at least 72,000 residents
were evacuated.
But no magma came. The evacuation
itself proved more destructive, costing
$342 million at the time — an estimated
60 percent of Guadeloupe’s annual gross
domestic product. And the cost was
more than economic.
“Scientific credibility took a hit,” says
Michael Poland, a geophysicist with the
U.S. Geological Survey. “The next time
you say there’s going to be a hazardous
eruption, people might blow you off.”
In the decades since, scientists have
been searching for ways to prevent
similar false alarms and avoid the worst-
case scenario: a deadly eruption that’s a
complete surprise.
Researchers aim to forecast eruptions
like we forecast a hurricane’s path and
intensity, and recent developments in
technology have helped researchers
close in on that goal. Improvements in
satellite capabilities have helped experts
detect subtle shifts in a volcano’s topog-
raphy and heat that could spell impend-
ing explosions. And new sensors can
pick up which gases are escaping volca-
noes’ vents in near-real time. Others can
detect underground noises — inaudible
to human ears — linked to
eruptions.
The new data has led
to tangible progress. In
October, Italian scientists
announced the results of
an eight-year test of an
automated system that
had been monitoring the
volcanic activity of Mount
Etna. The system sent out
text-message warnings
before 57 of the volcano’s
59 most recent eruptions.
During an eruption in
December, the warnings
went out only a few min-
utes before magma reached
the surface. But generally,
they had been going out
nearly an hour before,
says Mauricio Ripepe, a
University of Florence
volcanologist who helped
lead the project.
Still, early warnings aren’t the same as
forecasting an eruption’s probability —
or its possible destructiveness — days
in advance. To do that, someone would
need to combine all this new data to cre-
ate prediction models. So far, that hasn’t
happened.
“It’s mostly based on pattern recog-
nition,” Poland says about the current
warning system. When experts see
things like gas releases or swelling or
sinking in a volcano’s surface, their
reaction is, “ ‘Aha! That’s what we saw
last time.’ It’s usually right,” he says, but
“sometimes we get the size of the erup-
tion wrong. So it’s dangerous because of
that false confidence.”
It’s similar to where weather fore-
casting was a half-century ago, Poland
says. When the atmospheric pressure
dropped in a certain way, for example,
meteorologists predicted a cold spell.
The real world is more complex than
that, though, so predictions were
sometimes way off. Eventually, weather
experts incorporated sensor and satel-
lite data into models that
more closely mimic the
atmosphere.
For volcanoes, that
would mean account-
ing for the behavior
and characteristics of
different types of rock,
the various shapes of
underground magma
chambers, the different
ways in which magma
can flow, the way the
earth deforms slightly
near a volcanic site and
seismic activity nearby.
According to Poland,
we’ll likely see these
next-generation models
for the best-studied vol-
canoes first — Hawaii’s
Kilauea or Washington’s
Mount St. Helens, for
example — and they’d
eventually be applied to
all volcanoes.
“These models are a long way away,
but we’re not far from being able to start
doing the probabilities based on the
information we do have,” he says. “Even
if we don’t have that perfect model that
helps us forecast everything, we can
make progress on bits and pieces and
apply those.” – MATTHEW BERGER
Cloudy With a
Chance of Lava
New technology could help experts predict volcanic eruptions.
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BIG IDEA
We’ll see these
next-generation
models for the
best-studied
volcanoes
first — Hawaii’s
Kilauea or
Washington’s
Mount St.
Helens, for
example —
and they’d
eventually be
applied to all
volcanoes.