border: Outline of the study area. max-inundation-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. max-flow-depth: Raster images 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. time-series-points: To help emergency management personnel assess tsunami hazards, we supplement the inundation maps with the time series plots of the modeled water level and velocity dynamics at some on-land and some offshore locations in the communities. The plots are provided in the appendices of the report. These shapefiles provide the location of each time series point. tectonic-scenarios: Shapefiles that depict the modeled potential maximum inundation by tectonic waves for two groups of scenarios (scenarios 1-5 and scenarios 6-9), as well as scenario 10. These lines are illustrated in Figure 17 in the accompanying report.
Nicolsky, D.J., Suleimani, E.N., and Koehler, R.D., 2014, Tsunami inundation maps of the villages of Chenega Bay and northern Sawmill Bay, Alaska: Report of Investigation RI 2014-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. 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.
Appendices A1 through A3
Appendices A1 through A3
This project was supported by the National Oceanic and Atmospheric Administration (NOAA) under Reimbursable Service Agreement ADN 0931000 with the State of Alaska's Division of Homeland Security and Emergency Management. Some of the research in this publication is sponsored by the Cooperative Institute for Alaska Research with funds from the NOAA under cooperative agreement NA08OAR4320751 with the University of Alaska. 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. We thank Natalia Ruppert and Rod Combellick for providing valuable contributions to discussions on crustal and subduction-type tsunamigenic earthquakes, and Jacob Stroh for proofreading the manuscript. Reviews by Peter J. Haeussler and William Knight improved the report and maps.
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The results presented here are intended to provide guidance to local emergency management agencies in tsunami-hazard assessment, evacuation planning, and public education, to reduce damages from future tsunami hazards.
Nicolsky, D.J., Suleimani, E.N., and Hansen, R.A., 2013, Note on the 1964 Alaska Tsunami Generation by Horizontal Displacements of Ocean Bottom. Numerical Modeling of the Runup in Chenega Cove, Alaska: Pure and Applied Geophysics Vol. 170, Issue 9-10, doi: 10.1007/s00024-012-0483-7, Birkhauser Geoscience, Basel, Switzerland.
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.Online Links:
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.Online Links:
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.Online Links:
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.Online Links:
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.Online Links:
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.Online Links:
Nicolsky, D.J., Suleimani, E.N., and Koehler, R.D., 2014, Tsunami inundation maps of Cordova and Tatitlek, Alaska: Report of Investigation RI 2014-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
We present the results of numerical modeling of earthquake- generated tsunamis for the Sawmill Bay area and community of Chenega Bay, Alaska. Scenario 10 represents the worst-case scenario for the community of Chenega Bay. We note that although the occurrence of a Tohoku-type event is possible, the available geologic evidence suggests that repeated 1964-type events are a more realistic estimate of future earthquake displacements. The maps showing the results of our modeling have been completed using the best information available and are believed to be accurate, however, their preparation required many assumptions. We described several tectonic scenarios and provide an estimate of maximum credible tsunami inundation. Actual conditions during a tsunami event may vary from those considered, so the accuracy cannot be guaranteed. The limits of inundation shown should be used only as a guideline for emergency planning and response action. Actual areas inundated will depend on specifics of the earth deformations, on-land construction, and tide level, and they may differ from areas shown on the map. The information on this map is intended to provide a basis for 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.
The hydrodynamic model used to calculate propagation and runup of tsunami waves is a nonlinear, flux-formulated, shallow-water model. It passes the validation and verification tests required for models used in production of tsunami inundation maps. The source mechanism remains the biggest unknown in the problem of tsunami modeling. Since the initial condition for the modeling is determined by the displacement of the ocean bottom, the largest source of error is the earthquake model. When the tsunami is generated in the vicinity of the coast, the direction of the incoming waves, their amplitudes and times of arrival are determined by the initial displacements of the ocean surface in the source area because the distance to the shore is too small for the waves to dissipate. Therefore, the near-field inundation modeling results are especially sensitive to the fine structure of the tsunami source. Although the current model is validated to simulate the hypothetical inundation, it does not take into account the wave dispersion and cannot explicitly model origination and development of bore-like waves. The modeling process is highly sensitive to errors when the complexity of the source function is combined with its proximity to the coastal zone. During development of the tsunami inundation maps, a spatially averaged ground uplift/subsidence is assumed for the entire community of Chenega Bay. However, during a potential earthquake, soil compaction in areas of unconsolidated deposits in the coastal area might occur and the extent of the tsunami inundation could be farther landward. Finally, we mention that the horizontal resolution of the grid used for inundation modeling is 15 m (49 ft). This scale is limited by the resolution of the topographic and bathymetric data used for the grid construction. The 15 m (49 ft) resolution is high enough to describe major relief features; however, small topographic features, buildings, and other facilities cannot be accurately resolved by the existing model. More information about modeling uncertainties can be found in the companioning 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. 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.
Model validation for this report included modeling of the 1964 tsunami and comparison of the modeled results to observations that were recorded in the historic record. The dataset contains calculated tsunami inundation limits for tectonic source scenarios. However, tsunamis caused by underwater slope failures are also a significant hazard in the bays of coastal Alaska. Southcentral Alaska has a long record of tsunami waves generated by submarine and subaerial landslides, avalanches, and rock falls. While we acknowledge that coastal communities in Alaska are considered at risk from locally generated waves because of their proximity to landslide-prone areas in a seismically active zone, we did not quantify this category of tsunami hazard in the current report due to poor constraints on the parameters required for to build an appropriate model.
Model validation for this report included modeling of the 1964 tsunami and comparison of the modeled results to observations that were recorded in the historic record.
Are there legal restrictions on access or use of the data?
- Access_Constraints:
- 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).
- Use_Constraints:
- 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.
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| Data format: | shapefiles and raster files |
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<http://dx.doi.org/10.14509/29126> |
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