Geoscience Reference
In-Depth Information
of literature devoted to the physical characteristics of tsunamis (Keating, 2006; National
Research Council, 2007). One possible reason is that vulnerability is not an integral part of
the NTHMP and is not addressed by its subcommittees (Warning Coordination, Mapping and
Modeling, Mitigation and Education). The NTHMP Mitigation and Education Subcommittee
notes the importance of understanding vulnerability to tsunamis in the development of miti-
gation and education strategies but has not dedicated resources to doing such assessments
or providing guidelines on how to do so. Efforts to describe societal vulnerability to tsunamis
have come from other federal agencies (e.g., the USGS) and academic institutions. As the
tsunami research community increases its efforts into assessments of population exposure and
other elements of vulnerability assessment, it would beneit from leveraging ongoing efforts
for other hazards in the various agencies.
Individual and community vulnerability to tsunami hazards are dynamic processes that
require monitoring due to changing coastal populations, risk perceptions, and use of tsunami-
prone areas. Methods of characterizing vulnerability vary depending on the intended use of
the results (e.g., evacuation planning, land-use planning, infrastructure siting, and mitigation
projects). Due to the committee's focus on national preparedness to tsunamis, we limit our
discussion of vulnerability in this chapter to issues that relate to an individual's ability to evacu-
ate tsunami-prone areas, including (1) population exposure and sensitivity to tsunamis and
(2) evacuation potential for at-risk individuals in tsunami-prone areas. The purpose of this sec-
tion is to briely describe each element, progress in the nation's understanding of vulnerability,
and areas for improvement.
Population Exposure and Sensitivity
Tsunamis pose risks only if they have the potential to impact humans or things they value.
Therefore, a irst step in understanding vulnerability is to inventory the number and types of
individuals in tsunami hazard zones. Population exposure can be estimated for small geo-
graphic areas (e.g., a single coastal community) via building inventories in tsunami-prone areas
(Morgan, 1984; Papathoma et al., 2003; Wood and Good, 2004; Dall'Osso et al., 2006) or commu-
nity workshops that leverage local knowledge (Wood et al., 2002). For large geographic areas
(e.g., counties, states), decadal population data gathered by national census agencies (e.g., U.S.
Census Bureau) or business databases gathered by private companies can be integrated with
tsunami hazard data using GIS tools to determine the number of individuals in tsunami-prone
areas. Other regional approaches to estimating population exposure to tsunamis include
global population models (Balk et al., 2005), and landcover data (Wood, 2009).
In addition to determining the number of individuals in tsunami-prone areas, it is impor-
tant for emergency managers to assess their demographic characteristics, as these can amplify
an individual's potential for losses and affect their ability to receive and understand warning
messages (Mileti and Sorenson, 1990; Miller et al., 1999; Morrow, 1999; Cutter, 2003). People in
tsunami-prone areas will vary in their hazard awareness, risk perception and tolerance, and
ability to prepare or respond to an extreme event. If oficials are to effectively motivate people
