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Global Environmental Change, Resilience, and Sustainable Outcomes
certainly a natural hazard and also an excellent “laboratory” for understanding
human preparations and responses to sudden environmental change. As both
Ben Fitzhugh and Sheets point out, the direct impact of each form of volcanic
activity has a spatial signature that is different from others, depending on the
distance and direction from the epicenter. In some areas destruction and fatalities
are so complete that avoidance may be the only safe adaptation. In other
situations there is a warning; serious impacts can be avoided through mobility,
and the locality can be reoccupied relatively soon. Fitzhugh found that
settlements were not in the locations that would have been most vulnerable to
destruction from tsunamis, perhaps not because of recognition of that danger
itself but more likely prompted by the more frequent and sometimes devastating
ocean storms. This avoidance of vulnerable areas was more possible in the
Kuril Islands because of their low population density and the relative mobility
of their settlements, allowing residents to avoid and reoccupy areas relatively
soon after hazards hit. In fact, in both regions (and in the US Southwest as
well) the authors suggest that for some localities the long-term effect of volcanic
activity is positive because it improves agricultural potential and even
increases usable land surface in coastal or island situations.
Geography sometimes acts to draw settlements into vulnerable areas
because of its potential advantages. As Margaret Nelson and colleagues suggest
for the arid US Southwest, Daniel Sandweiss and Jeffrey Quilter for the
deserts of coastal Peru, and Tate Paulette for Mesopotamia, settlement along
river courses through otherwise arid terrain allows for irrigation agriculture
that could have supported large populations and advanced societies. To take
advantage of the potential of river water at the scale each of these societies did,
major investments in infrastructure were required to divert the water from the
rivers and distribute it across the fields. As Nelson and colleagues point out,
this made these societies “place-restricted” so that moving their settlements was
not easy to do; hence they were more or less “trapped” by their food-producing
technology. This caused them to be vulnerable to floods that would periodically
destroy much of the irrigation infrastructure, imposing a major reconstruction
cost on society. Some major floods, as in the Peruvian case, carried such sediment
loads that entire settlements could be destroyed; in extreme situations
the actual course of the river would change, leaving many major settlements
without their primary source of sustenance—as is hypothesized to have happened
in early Mesopotamian history. In other situations, as Emily McClung
de Tapia describes for Teotihuacan in central Mexico, the presence of a growing
city whose residents were originally attracted by environmental resources often
depletes those resources as its population and footprint grow. Hence the deforestation
surrounding Teotihuacan made it more vulnerable to flooding and soil
erosion, while at the same time the spread of the city itself consumed optimal
agricultural land, leading to a dual vulnerability in the long term.
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