What preventative measures can be taken to prevent damage and loss of
life once volcanologist predict an eruption?
Mark Northover
Dear Mark,
Probably the most important preventative measure is to know as much as
possible about the volcano's past. This is done by describing the types
of volcanic deposit (ash fall, pyroclastic flows, lahars, lava) and
mapping their distribution (where and how far did they travel away from
the volcano). The ages of these deposits will also be determined. With
this information, the volcanologists can get some idea of what the
volcano is likely to do. This type of information is available for many
(but not all) of the Cascade volcanoes (visit the
Cascade Volcano Observatory homepage) but is lacking
for most of the world's active and dormant volcanoes.
Volcanologists need real-time information about what is going on inside
the volcano. This is done with earthquake monitors (that track magma
movement), distance measurements (that measure swelling of the volcano),
and gas measurements (that detect the presence of magma or changes in the
magma). Once the volcano begins to erupt volcanologists want to collect
a sample of ash or lava. They want to know if any new magma is involved
or if old blocks from previous eruptions are being erupted. They also
want to know the composition of the material. Eruptions of basalt tend
to be less violent than eruptions of dacite or rhyolite.
Based on this information the volcanologists will advise local officials
responsible for public safety. These officials will decide if the
population needs to be evacuated, to where, for how long, etc...
Once the eruption starts there is little that can be done to reduce its
effects. One exception is the use of barriers and bombs to influence the
path of channelized lava flows (or lava tubes). Lava flows at Etna
volcano have been successfully diverted. Efforts in Hawaii have been
ambiguous.
For more information see the reference below.
One last point, some geologic surveys do a commendable job at trying to
educate the public about the hazards of the volcanoes (for example the
CVO homepage). Some people use this information wisely. Others ignore
it and build where they please, expecting the government to reimburse
them if nature takes its course. More people must take personal
responsibility in reducing the effects of volcanic eruptions.
Steve Mattox, University of North Dakota
Source of Information:
Wright, T.L., and Pierson, T.C., 1992, Living with volcanoes: U.S.
Geological Circular 1073, 57 p.
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