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Disasters: Risk Assessment, Management, and Post-Disaster Studies Using Remote Sensing
Published in Prasad S. Thenkabail, Remote Sensing Handbook, 2015
Talking of hazards in a broad sense—for example, the flood hazard, or the volcanic hazard—may be meaningful when describing general situations, or when communicating with decision makers or potentially exposed people. From a risk assessment and planning perspective, a more nuanced approach is needed, since those broad hazards, in a strict sense, do not exist. Flooding comes in many different types (riverine, coastal, flash flooding, among others), each with a unique behavior, and each requiring a different approach for their assessment and monitoring. Likewise, rock falls and debris flows are both gravity-driven mass movements, but both their genesis and behavior of movement differ dramatically. The volcanic hazard also does not exist; instead we can distinguish about 20 different hazardous processes that are associated with a volcano, some of which relate to magmatic or eruptive activity, while others are typical for dormant or extinct structures. Some of those specific or sub-hazards tend to affect a small area on the volcanic edifice itself (e.g., volcanic bombs or fumaroles), while others, such as gas and ash injected into the stratosphere, have global consequences. Some, such as seismic activity related to ascending magma, may last hours or days, while degassing can continue over decades or longer. A clear understanding of those specific processes is thus always needed before deciding on a suitable remote sensing strategy.
Volcanic activity
Published in F.G. Bell, Geological Hazards, 1999
Volcanic eruptions and other manifestations of volcanic activity are variable in type, magnitude, duration and significance as hazard. Volcanic hazard has been defined by Crandell et al. (1984) as a potentially damaging or destructive volcanic event. Ideally, in order to assess the significance of volcanic hazard it is helpful to estimate the time or period when a volcanic event is likely to occur, the frequency of such events, and the extent and frequency of areas likely to be affected. However, adequate data are seldom available to make such an assessment.
Planning to adapt: identifying key decision drivers in disaster response planning
Published in Civil Engineering and Environmental Systems, 2021
Charlotte O. Brown, Josh L. Hayes, Mark W. Milke
There are additional volcanic hazards that can occur during an eruption that are typically more destructive than volcanic ash (e.g. lahar, pyroclastic density currents, lava, volcanic ballistics). These hazards are likely to damage the built environment (e.g. building collapse, bridge failure) (Wilson et al. 2014; Jenkins et al. 2015), meaning the clean-up problem becomes much more involved than collecting and managing ash. Fires can also be induced by hot volcanic deposits or lava, as was observed in Heimaey, Iceland during the 1973 Heimaey eruption (Williams and Moore 1983) and more recently in Hawaii as a result of the 2018 eruption of Kīlauea (U.S. Department of the Interior Strategic Sciences Group 2019). Therefore, the presence of these hazards indicates that the waste stream will be highly mixed and will require a considerably different response than for volcanic ash alone. This raises additional considerations such as whether waste should be recycled or whether it is safe for the public to handle wastes. Therefore, where these hazards are likely to occur, indicators such as those described in the previous section would further enhance the ability to plan for these extreme volcanic events.