IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS002 Oral Presentation 1764
U.S. states and territories national tsunami hazard assessment, historic
record and sources for waves
Mrs. Paula Dunbar
National Geophysical Data Center National Oceanic and Atmospheric Administration
Craig Weaver
In 2005, the U.S. National Science and Technology Council (NSTC) released a joint report by the subcommittee
on Disaster Reduction and the U.S. Group on Earth Observations titled Tsunami Risk
Reduction for the United States: A Framework for Action (Framework). The first specific action called for
in the Framework is to Develop standardized and coordinated tsunami hazard and risk assessments for
all coastal regions of the United States and its territories. Since the National Oceanic and Atmospheric
Administration (NOAA) is the lead agency for providing tsunami forecasts and warnings and NOAAs
National Geophysical Data Center (NGDC) catalogs information on global historic tsunamis, NOAA/NGDC
was asked to take the lead in conducting the first national tsunami hazard assessment. Earthquakes or
earthquake-generated landslides caused more than 85% of the tsunamis in the NGDC tsunami
database. Since the United States Geological Survey (USGS) conducts research on earthquake hazards
facing all of the United States and its territories, NGDC and USGS partnered together to conduct the first
tsunami hazard assessment for the United States. A complete tsunami hazard and risk assessment
consists of a hazard assessment, exposure and vulnerability assessment of buildings and people, and
loss assessment. This report is an interim step towards a tsunami risk assessment. The goal of this
report is to provide a qualitative assessment of the tsunami hazard at the national level. The core of the
assessment involved dividing the NGDC historical tsunami database based on the measured runup
heights and the number of runups at each height. Although tsunami deaths are a measure of risk rather
than hazard, the known tsunami deaths found in the NGDC database search compare favorably with the
qualitative assessment based on frequency and height. The second assessment method used the USGS
estimates of recurrence of possible tsunami-generating earthquakes near American coastlines to extend
the NOAA/NGDC tsunami database back in time. Combining the two techniques shows that the
American tsunami hazard is highest for all Pacific basin states, possessions, and those in the Caribbean.
The number of high runups in Alaska and Hawaii indicate that the tsunami hazard is very high in those
states. In contrast, the tsunami hazard is low along the Atlantic seaboard and very low for the Gulf
coast states.
Keywords: tsunami, earthquake, hazard assessment