Volcanoes & Montserrat
Dateline: August, 1996
Here are the facts and a review of what is
known so far.
- On the island of Montserrat, the Soufriere Hills volcano
is active. By early April 1996, increasing activity foced
government authorities to evacuate the capital city of Plymouth.
- Scientists are studying volcanic data to predict eruptions.
- The volcano on Montserrat is a stratovolcano, or composite
volcano made up of layers of tephra, ash, and lava flows,
much like Mt. Pinatubo in the Philippines.
- Studying these facts may help to understand the Montserrat
situation more fully:
- The Earth has layers: the lithosphere; the hot, convecting
mantle; and the dense iron core.
- Huge tectonic plates in the lithosphere constantly move
at rates of centimeters per year in response to changes
in the semi-liquid mantle. Major geological events, such
as earthquakes, volcanic eruptions, and mountain building,
result from these plate motions.
- Landforms are the result of a combination of constructive
and destructive forces. Constructive forces include deformation
of the Earth’s crust and volcanic eruptions. Destructive
forces include weathering and erosion.
- Some changes are part of the "rock cycle."
Volcanoes contribute to the rock cycle by bringing molten
rocks to the surface to create new landforms. Over the
ages, these landforms weather and erode, creating sediments
that may be buried, then compacted, heated, remelted and
recrystallized to form new rock. Eventually, those new
rocks may be brought to the surface again and the cycle
- Dangers on the island of Montserrat are many. The volcano
may create lava flows, pyroclastic flows, and landslides.
Lahars may occur after rainstorms. Falling tephra may land
on people or buildings causing harm.
- Predicting an eruption is not an exact science. Scientists
study patterns of past eruptions and apply the lessons they
learn to real-time data.
- To understand volcanic activity on Montserrat one should
examine changes in land deformation, ash clouds, and volcanic
tremor and rockfall events (VT and RF).