Volcanic risk
Volcanoes can have a wide variety of impacts on humans. These range from effects at very
localized scales, such as lava flows burying buildings or roads, to
intermediate scales when pyroclastic flows, debris avalanches, and ash fallout
cause damage over hundreds to thousands of square kilometers, and to the
largest scale where major land areas are inundated with ash and global climate
is altered for several years. In
fact, volcanoes can effectively cause every kind of natural disaster on some
scale, including earthquakes, fires, landslides, tsunamis, flooding, and even
extreme winds (such as in a pyroclastic surge or flow). Unfortunately, population growth,
coupled with the benefits provided by volcanoes (e.g., fertile soils,
geothermal energy, beautiful scenery, mineral deposits, and raw building
materials) means that humans are increasingly vulnerable to volcanic
processes. Risk assessment is an
important way that geoscientists can use their understanding of volcanic
processes to improve planning and preparedness, as well as to help cope with
the aftermath of an eruption, and thereby save lives.
Volcanic
risk assessment has three components.
The first involves defining the type of volcanic event(s) that is of
concern in a given situation.
Event definition requires an understanding of the types of processes
that have occurred in the past at a volcano or volcanic field, along with an
understanding of the population, infrastructure, or facilities that might be
affected. The second component
focuses on establishing the likelihood that the defined event(s) will
occur. For an active or awakening
volcano, this might include interpretation of remote sensing, geophysical, and
geochemical data within the context of a model for how the volcanic system
works. In other cases, such as
monogenetic volcanic fields (see Basaltic
volcanism), there may be no immediate indicators of future activity,
and event likelihood must depend on projecting the geologic record forward in
time in terms of eruption frequency and location. In both cases, probabilistic techniques are an important
method for incorporating data and model uncertainty and providing a realistic
estimate of future activity. The
third component of risk assessment is predicting the effects or consequences of
an event. Again, this requires
knowledge of the population, infrastructure, and facilities that could be
affected, as well as the dynamic conditions associated with the volcanic event
(predicted, for example, by theoretical
and numerical modeling) and the response of people and structures to
those conditions.
My work in volcanic risk assessment to date has focused on
the impacts of pyroclastic flows on buildings, numerical model predictions of
pyroclastic flow conditions, and the probability and consequences of a basaltic
volcano erupting through the proposed radioactive waste repository at Yucca
Mountain, Nevada (U.S.A.). My
ongoing interests in this area include risk to urban areas located in or near
volcanic fields, continued refinement of numerical models of eruptive processes
and coupling with infrastructure response characteristics, and linking to
larger systems models that study the ripple effects of societal and infrastructure
disruption from volcanic and other natural disasters.