Geoscience Reference
In-Depth Information
the coastal communities after the earthquake is felt. In addition, tsunami observations dem-
onstrate an increase in wave height with proximity to the source, resulting in extensive coastal
looding by a near-ield tsunami. Consequences of a near-ield tsunami are far greater for any
given location.
Far-ield tsunamis afford hours of advance notice for evacuation and are likely to have
smaller wave heights than those in the tsunami's near ield. However, the farther a coastal com-
munity from the earthquake source the less likely it is to have felt the earthquake and the more
dependent it is on an instrumental detection system to provide warnings. Timely and accurate
warnings are required to implement orderly evacuations and to avoid frequent unnecessary
evacuations, which can be costly. The National Science and Technology Council (NSTC) report
(2005) concludes that “the challenge is to design a tsunami hazard mitigation program to pro-
tect life and property from two very different types of tsunami events.”
GOALS AND SCOPE OF THIS REPORT
The 2004 Indian Ocean tsunami, spurred two congressional acts intended to reduce losses
of life and property from future tsunamis. The Emergency Supplemental Appropriations Act for
Defense, the Global War on Terror, and Tsunami Relief, 2005 (P.L. 109-13), included $24 million to
improve tsunami warnings by expanding tsunami detection and earthquake monitoring capa-
bilities. This Act was followed in 2006 by the Tsunami Warning and Education Act (P.L. 109-424),
which directs the National Oceanic and Atmospheric Administration (NOAA) to strengthen the
nation's tsunami warning system (TWS), work with federal and state partners toward the miti-
gation of tsunami hazards, establish and maintain a tsunami research program, and assist with
efforts to provide tsunami warnings and tsunami education overseas.
Section 4(j) of the Tsunami Warning and Education Act calls upon the National Academy
of Sciences (NAS) “to review the tsunami detection, forecast, and warning program established
under this Act to assess further modernization and coverage needs, as well as long-term
operational reliability issues.” In response, NOAA asked the NAS to assess options to improve
all aspects of the tsunami program. This request is relected in the irst part of the committee's
charge (see Appendix B) and accordingly focuses on efforts on tsunami detection, forecasting,
and warning dissemination.
The NAS, in accepting this charge and in consultation with NOAA, broadened the review's
scope to include an assessment of progress toward additional preparedness efforts to reduce
loss of life and property from tsunamis in the United States as part of the National Tsunami
Hazard Mitigation Program (NTHMP). The main rationale for this broadened scope was to
address Section 5(a) in P.L. 109-424, which called for “a community-based tsunami hazard
mitigation program to improve tsunami preparedness of at-risk areas in the United States and
its territories.” Such a tsunami hazard mitigation program requires partnership among federal,
state, tribal, and local governments. Its strategies include identifying and deining tsunami
hazards, making inventories of the people and property in tsunami hazard zones, and provid-
ing the public with knowledge and infrastructure for evacuation, particularly for near-ield
