mhhw-shoreline: The modern shoreline (mean higher high water - MHHW) of the study area at the time of publication; see Grid Development and Data Sources section of this report to learn more about how this file was created. hypothetical-composite-line: Estimated, "maximum credible scenario" inundation line that encompasses the maximum extent of flooding based on model simulation of all credible source scenarios and historical observations. The "maximum credible scenario" inundation line becomes a basis for local tsunami hazard planning and development of evacuation maps. hypothetical-composite-line-half-m-depth: Extent of potential 0.5 meter water flow depth hypothetical-composite-line-two-m-depth: Extent of potential 2 meter water flow depth tectonic-scenario-01: Scenario 1. Repeat of the 1964 event: Source function based on coseismic deformation model by Johnson and others (1996) tectonic-scenario-02: Scenario 2. Repeat of the 1964 event: Source function based on coseismic deformation model by Suito and Freymueller (2009) tectonic-scenario-05: Scenario 5. Rupture of the Cascadia zone, including portions of the margin along the British Columbia and northern California shores landslide-scenario-10: Scenario 10. Repeat of the 1964 event: Major underwater slide complexes of the 1964 earthquake - Harbor, Airport, and Glacier (HAG) landslides landslide-scenario-11: Scenario 11. Hypothetical event: Major underwater slide complex offshore of the northern shore of Passage Canal landslide-scenario-12: Scenario 12. Hypothetical event: Major underwater slide complex offshore of the Billings Creek delta landslide-scenario-13: Scenario 13. Hypothetical event: Simultaneous failure of underwater slide complexes described by scenarios 10-12 max-flow-depth: Raster image depicting maximum composite flow depths over dry land. Pixel values provide the modeled depth (in meters) of maximum inundation. For each grid point, the pixel value provides the modeled depth of water (in meters) over previously dry land, representing the maximum depth value of all calculated tsunami scenarios.
Nicolsky, D.J., Suleimani, E.N., Combellick, R.A., and Hansen, R.A., 2011, Tsunami inundation maps of Whittier and western Passage Canal, Alaska: Report of Investigation RI 2011-7, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
This is a vector data set.
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest .000001. Longitudes are given to the nearest .000001. Latitude and longitude values are specified in decimal degrees.
The horizontal datum used is World Geodetic System of 1984.
The ellipsoid used is WGS 84.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257223563.
This project was supported by the National Oceanic and Atmospheric Administration grants 27-014d and 06- 028a through Cooperative Institute for Arctic Research. Numerical calculations for this work were supported by a grant of High Performance Computing (HPC) resources from the Arctic Region Supercomputing Center (ARSC) at the University of Alaska Fairbanks as part of the U.S. Department of Defense High Performance Computing Modernization Program. Reviews by Dr. Timothy Walsh and Dr. Juan Horrillo improved the report and maps. We thank R. Grapenthin and B. Witte for their help with the RTK GPS survey in Whittier.
The purpose of this study is to evaluate potential tsunami hazards for the community of Whittier and western Passage Canal area. We numerically model the extent of inundation due to tsunami waves generated from earthquake and landslide sources. Tsunami scenarios include a repeat of the tsunami triggered by the 1964 Great Alaska Earthquake, as well as tsunami waves generated by a hypothetically extended 1964 rupture, a hypothetical Cascadia megathrust earthquake, hypothetical earthquakes in Prince William Sound, and Kodiak asperities of the 1964 rupture. Local underwater landslide and rockslide events in Passage Canal are also considered as credible tsunamigenic scenarios. Results of numerical modeling combined with historical observations in the region are intended to provide guidance to local emergency management agencies in tsunami hazard assessment, evacuation planning, and public education for reducing future tsunami damage.
Caldwell, R.J., Eakins, B.W., and Lim, E., 2011, Digital elevation models of Prince William Sound, Alaska-Procedures, data sources and analysis: NOAA Technical Memorandum NESDIS NGDC-40, National Geophysical Data Center, Marine Geology and Geophysics Division, United States.
Nicolsky, D.J, Suleimani, E.N, and Hansen, R.A, 2011, Validation and verification of a numerical model for tsunami propagation and runup: Pure and Applied Geophysics v. 168, Birkhauser Geoscience, Switzerland.
Suito, Hisashi, and Freymueller, J.T, 2010, A viscoelastic and afterslip postseismic deformation model for the 1964 Alaska earthquake: Journal of Geophysical Research v. 114, no. B11, American Geophysical Union, Washington, DC, United States.
Kachadoorian, Reuben, 1965, Effects of the earthquake of March 27, 1964, at Whittier, Alaska: Professional Paper P 542-B, U.S. Geological Survey, United States.
Johnson, J.M., Satake, Kenji, Holdahl, S.R., and Sauber, Jeanne, 1996, The 1964 Prince William Sound earthquake-Joint inversion of tsunami waveforms and geodetic data: Journal of Geophysical Research v. 101, no. B1, American Geophysical Union, Washington, DC, United States.
Data sources used in this process:
Data sources used in this process:
Data sources used in this process:
Nicolsky, D.J., Suleimani, E.N., Haeussler, P.J., Ryan, H.F., Koehler, R.D., Combellick, R.A., and Hansen, R.A., 2013, Tsunami inundation maps of Port Valdez, Alaska: Report of Investigation RI 2013-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
Suleimani, E.N., Combellick, R.A., Marriott, D., Hansen, R.A., Venturato, A.J., and Newman, J.C., 2005, Tsunami hazard maps of the Homer and Seldovia areas, Alaska: Report of Investigation RI 2005-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
Suleimani, E.N., Hansen, R.A., Combellick, R.A., and Carver, G.A., 2002, Tsunami hazard maps of the Kodiak area, Alaska: Report of Investigation RI 2002-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
Suleimani, E.N., Nicolsky, D.J., West, D.A., Combellick, R.A., and Hansen, R.A., 2010, Tsunami inundation maps of Seward and northern Resurrection Bay, Alaska: Report of Investigation RI 2010-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
Suleimani, E.N., Nicolsky, D.J., and Koehler, R.D., 2013, Tsunami inundation maps of Sitka, Alaska: Report of Investigation RI 2013-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
The extent of inundation caused by hypothetical future tsunami waves was calculated using numerical modeling of tsunami wave propagation and runup. The final, highest resolution grid of the western Passage Canal, where the inundation extent was calculated, has a spacing of approximately 15 meters. Although the location of the inundation line has an accuracy of approximately plus or minus 15 m horizontally relative to the grid spacing, the true location accuracy is unknown, because of the complex modeling process the accuracy depends on many factors. These factors include correctness of the earthquake source model, accuracy of the bathymetric and topographic data, soil compaction in areas of unconsolidated deposits and the adequacy of the numerical model in representing the generation, propagation, and run-up of tsunami waves. Actual areas inundated will depend on specifics of earth deformations, on-land construction, and tide level, and may differ from areas shown on the map. The limits of inundation shown should only be used as a guideline for emergency planning and response action. The information is intended to permit state and local agencies to plan emergency evacuation and tsunami response actions in the event of a major tsunamigenic event. These files are not intended for land-use regulation, property valuation, or any use other than the stated purpose. Users should review the accompanying report, particularly the Sources of Errors and Uncertainties section, for a detailed discussion of limitations of the methods used to generate the various inundation models.
The extent of tsunami inundation in Whittier was calculated through numerical modeling of water waves over realistic bathymetry and topography. The input data for the tsunami model includes the combined topographic and bathymetric DEM of 15-m resolution described in NGDC NOAA report "Digital elevation models of Prince William Sound, Alaska-Procedures, Data Sources and Analysis" by Caldwell, R.J., Eakins, B.W., and Lim, E. According to the corresponding metadata file, the accuracy of the high-resolution DEM developed is determined by the topographic datasets with the vertical accuracy of 10-15 m (33-50 ft). Since the DEM can posses large vertical errors near the shoreline, the topographic datasets are augmented with high-accuracy data, that is, a real time kinematic (RTK) GPS survey within the harbor area and along near-shore areas in Whittier. We estimate that the GPS observations have the vertical accuracy of 1 m (3.3 ft) in flat-lying areas where there are no abrupt topographic changes. Finally, we note that the collected GPS measurements are recorded in WGS84 horizontal datum, with the horizontal accuracy of approximately 3-5 m (10-16 ft). For additional information please reference the "Grid development and data sources" section of this report.
The vertical accuracy of the inundation modeling is dependent on the accuracy and resolution of the digital elevation models (DEMs) and tidal datum values that were used to compile the computational grid. We provide additional details about DEM and grid development in the accompanying report. Prior to scenario modeling, bathymetric data were shifted to use Mean Higher High Water (MHHW) as the vertical datum. The depths of inundation shown should be used only as a guideline for emergency planning and response action. Actual inundation water depth will depend on specifics of the earth deformations, on-land construction, and tide level, and they may differ from areas shown by this data. The information is intended to permit state and local agencies to plan emergency evacuation and tsunami response actions in the event of a major tsunamigenic earthquake. These results are not intended for land-use regulation or building-code development. For additional information please reference the Grid Development and Data Sources section of the associated manuscript.
We modeled inundation extents resulting from 14 different scenarios (tsunami, landslide, and rockfall). Each scenario is described in the text report. This digital data distribution package presents shapefiles that outline the extent of the scenarios that produced a "significant" inundation in Whittier. We also include two additional shapefiles that outline where the modeled water depth of the maximum innundation scenario is expected to be 0.5 and 2 meters. The inundation limits and flow depths are results of numerical modeling of tsunami waves with the use of shallow water equations. We conducted all model runs using bathymetric data that correspond to Mean Higher High Water so that the resulting maximum inundation line represents a reasonable worst-case scenario of tsunami occurrence at high tide. The model does not take into account the periodical change of sea level due to tides, but it does include the effect of local uplift or subsidence during the earthquake. The average recurrence intervals for the tectonic source events are poorly known. Scenarios 1 and 2, which are repeats of the magnitude 9.2 great earthquake of 1964, have an estimated median recurrence interval of 589 years, based on paleoseismic data (Carver and Plafker, 2008). The recurrence intervals for tsunamigenic underwater landslides in Passage Canal is unknown. The recurrence interval for the potential rockfall-generated tsunami is also unknown. The data used to calculate the potential extent of tsunami inundation includes: high-resolution topography and bathymetry of Passage Canal, historic records of the 1964 inundation line at Whittier, historic seismicity measurements, pre- and post-1964 bathymetric profiles in the western part of Passage Canal, and related tectonic geometry. The western part of Passage Canal has been studied in great detail and we feel that the density of available information is sufficient to allow for confidence in our interpretations of likely extents of tsunami inundation. The potential rockfall area require additional in-situ measurements to constrain volume, configuration and dynamics of the potential rockfall failure.
Results of numerical modeling were verified by simulating historic tsunamis. Inundation lines are visually inspected using GIS software for identification of anomalous elevations or data inconsistencies. See text report for detailed explanation of the tests used to determine the fidelity among the various data sources that were used to generate this dataset.
Are there legal restrictions on access or use of the data?
- This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
- This dataset includes results of numerical modeling of earthquake-generated tsunami waves for a specific community. Modeling was completed using the best information and tsunami modeling software available at the time of analysis. They are numerical solutions and, while they are believed to be accurate, their ultimate accuracy during an actual tsunami will depend on the specifics of earth deformations, on-land construction, tide level, and other parameters at the time of the tsunami. Actual areas of inundation may differ from areas shown in this dataset. Landslide tsunami sources may not be included in the modeling due to unknown potential impact of such events on a given community; please refer to accompanying report for more information on tsunami sources used for this study. The limits of inundation shown should only be used as a general guideline for emergency planning and response action in the event of a major tsunamigenic earthquake. These results are not intended for any other use, including land-use regulation or actuarial purposes. Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
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