| Can we predict when a volcano will
erupt? Scientists can often find clues
about past eruptions by studying the deposits left
behind. Areas affected by lava flows, debris flows,
tephra, or pyroclastic flows can be mapped, making
disaster planning more effective. In addition to this
type of long-range forecasting, scientists are becoming
more and more skilled at spotting the warning signs of an
eruption.
|
Scientists measure
sulfur dioxide levels
using a correlation
spectrometer
(COSPEC). |
Warning
Signs
Before an eruption, magma moves into the area beneath the
volcano and collects in a magma chamber, or reservoir. As
it comes closer to the surface, the magma releases gases.
These events can offer valuable clues about the
likelihood of an eruption. For example, the movement of
magma produces small earthquakes and vibrations
(seismicity). Magma gathering in a chamber causes slight
swelling of the volcano's slopes. Gases released near the
volcano can be measured for changes in quantity and
makeup.
Monitoring
Methods
A number of tools can be used to record these warning
signs. Seismographs can detect small earthquakes, while
tiltmeters and geodimeters can measure the subtle
swelling of a volcano. Correlation spectrometers
(COSPECS) can measure amounts of sulfur dioxide--a
telltale gas that is released in increasing quantities
before an eruption. Using these and other tools, it's
possible to closely monitor activity at an awakening
volcano.
The Problem of
Prediction
Volcanologists are becoming very skilled at predicting
the likelihood of an eruption. Still, a number of
barriers remain. It's very difficult to pinpoint exactly
when an eruption will happen. Often, moving magma doesn't
result in an eruption, but instead cools below the
surface. Monitoring potential eruptions is expensive.
With many volcanoes erupting only every few hundred or
thousand years, it's not possible to monitor every site.
Volcanic eruptions don't occur without warning, however.
If we set up monitoring devices, we should not be caught
off guard by disastrous eruptions.
[Read More About FORECASTING]
|
