| Data from volcano-monitoring studies constitute the only
scientifically valid basis for short-term forecasts of a future eruption, or of
possible changes during an ongoing eruption. Thus, in any effective
hazards-mitigation program, a basic strategy in reducing volcano risk is the
initiation or augmentation of volcano monitoring at historically active
volcanoes and also at geologically young, but presently dormant, volcanoes
with potential for reactivation. Beginning with the 1980s, substantial
progress in volcano-monitoring techniques and networks – ground-based as
well space-based – has been achieved. Although some geochemical monitoring
techniques (e.g., remote measurement of volcanic gas emissions) are being
increasingly applied and show considerable promise, seismic and geodetic
methods to date remain the techniques of choice and are the most widely
used. Availability of comprehensive volcano-monitoring data was a decisive
factor in the successful scientific and governmental responses to the
reawakening of Mount St. elens (Washington, USA) in 1980 and, more
recently, to the powerful explosive eruptions at Mount Pinatubo (Luzon,
Philippines) in 1991. However, even with the ever-improving state-of-the-art
in volcano monitoring and predictive capability, the Mount St. Helens and
Pinatubo case histories unfortunately still represent the exceptions, rather
than the rule, in successfully forecasting the most likely outcome of
volcano unrest. |