Tsunami inundation maps for the communities of Chignik and Chignik Lagoon, Alaska

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What does this data set describe?

Title:
Tsunami inundation maps for the communities of Chignik and Chignik Lagoon, Alaska
Abstract:
Potential tsunami hazard for the Alaska Peninsula communities of Chignik and Chignik Lagoon is evaluated by numerically modeling the extent of inundation from tsunami waves generated by hypothetical earthquake sources. Worst-case hypothetical scenarios are defined by analyzing results of a sensitivity study of the tsunami dynamics related to various slip distributions along the Alaska-Aleutian megathrust. The worst-case scenarios for Chignik area communities are thought to be thrust earthquakes along the Alaska Peninsula with their greatest slip at 5-35 km (3.1-22 mi) depth. We also consider Tohoku-type ruptures and an outer-rise rupture along the Alaska Peninsula. The maximum predicted water depth on Anderson Street in Chignik Bay is about 31 m (102 ft), while the water depth on Henry Street in Chignik Lagoon is about 11 m (36ft). Maximum current velocity in the ocean could exceed 9 m/s (17 kt) and significant wave action could continue for at least 8 hours after the earthquake. Results presented here are intended to provide guidance to local emergency management agencies in tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards.
Supplemental_Information: 
border:    Outline of the study area.
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.
max-inundation-line:    Estimated, "maximum credible scenario" inundation line(s) that encompasses the maximum extent of flooding based on model simulation of all credible source scenarios and historical observations. The "maximum credible scenario" inundation lines are intended to be utilized as a basis for local tsunami hazard planning and development of evacuation maps.
scenarios:    Collection of shapefiles that depict the modeled potential maximum inundation by tectonic waves for each modeled scenario. Detailed information about each scenario can be found in the accompanying report.
time-series-points-chignik:    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.
time-series-points-chignik-lagoon:    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.
  1. How should this data set be cited?

    Nicolsky, D.J., Suleimani, E.N., and Koehler, R.D., 2016, Tsunami inundation maps for the communities of Chignik and Chignik Lagoon, Alaska: Report of Investigation RI 2016-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 48 p., 2 sheets, scale 1:12,500.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -158.570130
    East_Bounding_Coordinate: -158.343459
    North_Bounding_Coordinate: 56.355703
    South_Bounding_Coordinate: 56.289328

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 2013
    Ending_Date: 2016
    Currentness_Reference: publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: report and digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a vector data set.

    2. What coordinate system is used to represent geographic features?

      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.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean Higher High Water
      Depth_Resolution: 1
      Depth_Distance_Units: meter
      Depth_Encoding_Method: Attribute values

  7. How does the data set describe geographic features?

    ri2016-8-border
    Outline of the study area. File format: shapefile (Source: Alaska Division of Geological & Geophysical Surveys (DGGS) and Alaska Earthquake Center, Geophysical Institute, University of Alaska)

    ri2016-8-max-flow-depth-chignik
    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. File format: GeoTIFF (Source: Alaska Earthquake Center, Geophysical Institute, University of Alaska, this report)

    ri2016-8-max-inundation-line-chignik
    Estimated, "maximum credible scenario" inundation line(s) that encompasses the maximum extent of flooding based on model simulation of all credible source scenarios and historical observations. The "maximum credible scenario" inundation lines are intended to be utilized as a basis for local tsunami hazard planning and development of evacuation maps. File format: shapefile (Source: Alaska Earthquake Center, Geophysical Institute, University of Alaska, this report)

    ri2016-8-scenarios-chignik
    Collection of shapefiles that depict the modeled potential maximum inundation by tectonic waves for each modeled scenario. Detailed information about each scenario can be found in the accompanying report. File format: shapefile (Source: Alaska Earthquake Information Center, Geophysical Institute, University of Alaska, this report)

    ri2016-8-time-series-points-chignik
    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. File format: shapefile (Source: Alaska Earthquake Center, Geophysical Institute, University of Alaska, this report)

    Number
    Numbers correspond to labeled points and graphs shown in the accompanying report. (Source: this report)

    Appendices A and B

    Label
    Labels correspond to titles of graphs shown in the accompanying report. (Source: this report)

    Appendices A and B

    ri2016-8-time-series-points-chignik-lagoon
    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. File format: shapefile (Source: Alaska Earthquake Center, Geophysical Institute, University of Alaska, this report)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    This project received support from the National Oceanic and Atmospheric Administration (NOAA) under Reimbursable Service Agreements ADN 942017 and 952011 with the State of Alaska's Division of Homeland Security and Emergency Management (a division of the Department of Military and Veterans Affairs). 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. A thoughtful review by De Anne Stevens improved the report and maps. We also would like to thank Peter Hickman from the Geographic Information Network of Alaska (GINA) for help with selecting the base layer imagery.

  3. To whom should users address questions about the data?

    Alaska Division of Geological & Geophysical Surveys
    GIS Manager
    3354 College Rd
    Fairbanks, AK 99709-3707
    USA

    907-451-5020 (voice)
    dggsgis@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays

Why was the data set created?

Results presented here are intended to provide guidance to local emergency management agencies in tsunami inundation assessment, evacuation planning, and public education to mitigate future tsunami hazards.

How was the data set created?

  1. From what previous works were the data drawn?

    Nicolsky, D.J. and others, 2011 (source 1 of 8)
    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:

    Other_Citation_Details: 65 p
    Type_of_Source_Media: paper
    Source_Contribution: Model verification

    Nicolsky, D.J. and others, 2015 (source 2 of 8)
    Nicolsky, D.J., Suleimani, E.N., Freymueller, J.T., and Koehler, R.D., 2015, Tsunami inundation maps of Fox Islands communities, including Dutch Harbor and Akutan, Alaska: Report of Investigation RI 2015-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 67 p., 2 sheets, scale 1:12,500
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 12500
    Source_Contribution: Model verification

    Nicolsky, D.J. and others, 2013 (source 3 of 8)
    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:

    Other_Citation_Details: 77 p., 1 sheet, scale 1:12,500
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 12500
    Source_Contribution: Model verification

    Nicolsky, D.J. and others, 2011 (source 4 of 8)
    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.

    Type_of_Source_Media: paper
    Source_Contribution: Model verification

    Nicolsky, D.J. and others, 2014 (source 5 of 8)
    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:

    Other_Citation_Details: 49 p
    Type_of_Source_Media: paper
    Source_Contribution: Model verification

    Suleimani, E.N. and others, 2010 (source 6 of 8)
    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:

    Other_Citation_Details: 47 p., 3 sheets, scale 1:12,500
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 12500
    Source_Contribution: Model verification

    Suleimani, E.N. and others, 2013 (source 7 of 8)
    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:

    Other_Citation_Details: 76 p., 1 sheet, scale 1:250,000
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 250000
    Source_Contribution: Model verification

    Suleimani, E.N. and others, 2015 (source 8 of 8)
    Suleimani, E.N., Nicolsky, D.J., and Koehler, R.D., 2015, Tsunami inundation maps of Elfin Cove, Gustavus, and Hoonah, Alaska: Report of Investigation RI 2015-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 79 p
    Type_of_Source_Media: paper
    Source_Contribution: Model verification

  2. How were the data generated, processed, and modified?

    Date: 2015 (process 1 of 7)
    Development of nested grids - To support inundation modeling of coastal areas in Alaska, we used a series of nested telescoping grids, or digital elevation models (DEMs), as input layers for tsunami inundation modeling and mapping. These grids of increasing resolution allowed us to propagate waves generated by various sources to Chignik and Chignik Lagoon. In order to propagate a wave from its source to various coastal locations we used embedded grids, placing a large, coarse grid in deep water and coupling it with smaller, finer grids in shallow water areas. The bathymetric and topographic relief in each nested grid is based on digital elevation models (DEMs) developed at the National Geophysical Data Center (NGDC) of the National Oceanic Atmospheric Administration (NOAA), in Boulder, Colorado. The extent of each grid used for our tsunami inundation mapping is listed in the accompanying report. To provide greater DEM accuracy near the shorelines, we augmented the topographic datasets with RTK - GPS survey measurements. Survey measurements were converted to MHHW datum using methods described within the associated report. See Methodology and Data section of the accompanying report for more detail and additional grid development source information.

    Date: 2015 (process 2 of 7)
    Model validation - The numerical model that we used for simulation of tsunami wave propagation and runup was validated through a set of analytical benchmarks and tested against laboratory data. The model solves nonlinear shallow water equations using a finite-difference method on a staggered grid. See the accompanying report for more detail and additional model information.

    Date: 2015 (process 3 of 7)
    Model verification - To estimate tsunami propagation and runup in the Chignik area, we use the same numerical model employed in other Alaska tsunami inundation studies (for example Suleimani and others, 2010, 2013, 2015, and Nicolsky and others, 2011a, 2013, 2014, 2015).

    Data sources used in this process:

    • Nicolsky, D.J. and others, 2011
    • Nicolsky, D.J. and others, 2015
    • Nicolsky, D.J. and others, 2013
    • Nicolsky, D.J. and others, 2011
    • Nicolsky, D.J. and others, 2014
    • Suleimani, E.N. and others, 2010
    • Suleimani, E.N. and others, 2013
    • Suleimani, E.N. and others, 2015

    Date: 2015 (process 4 of 7)
    Numerical simulations of hypothetical tsunami scenarios - We assessed hazard related to tectonic tsunamis in Chignik and Chignik Lagoon by performing model simulations for each hypothetical source scenario. Numerical results for each scenario include extent of inundation, sea level and velocity time series calculations, and tsunami flow depth. See the accompanying report for more detail and additional information.

    Date: 2015 (process 5 of 7)
    Compilation of maximum inundation zone and maximum flow depths - We calculated the maximum composite extent of inundation by combining the maximum calculated inundation extents of all scenarios. The same method was used for calculation of maximum flow depths over dry land. See the accompanying report for more detail and additional information.

    Date: 2015 (process 6 of 7)
    Calculation of the potential inundation lines - For each grid cell in the high-resolution DEMs Chignik and Chignik Lagoon, we determined whether the cell was inundated by waves or stayed dry throughout the entire simulation. Then, we defined a function such that it is equal to one at the center of each wet cell and is negative one at the center of each dry cell. Using a linear interpolation algorithm in Matlab, we plotted a zero-value contour that delineates dry and wet cells from each other. The resultant contour line (or a collection of lines if the contour is not a simply connected) was directly exported to the ArcGIS using WGS84 datum.

    Date: 2017 (process 7 of 7)
    Shapefiles of inundation scenarios were updated to remove edge-line artifacts.

  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    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 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. This DGGS Report of Investigations is a final report of scientific research. Several scientists familiar with the subject matter provided technical reviews. Uncertainties associated with the depiction or interpretation of various features are discussed in the manuscript.

  2. How accurate are the geographic locations?

    The hydrodynamic model used to calculate propagation and runup of tsunami waves is a nonlinear, flux-formulated, shallow-water model that has passed the validation and verification tests required for models used in the production of tsunami inundation maps. Because of the shallow bathymetry in Chignik Lagoon, the hypothetical tsunami is likely to impact the village as a bore (a single, breaking wavefront followed by a train of secondary waves). Therefore, the so-called Boussinesq-type models may be more appropriate in modeling propagation of these waves. However, it was illustrated in the 2011 NTHMP Model Validation Workshop that the classical shallow-water models are probably adequate to predict the runup in most geophysical conditions. Further details about the limitations of the employed modeling approach are described in earlier reports by Suleimani and others and Nicolsky and others, as well as in NTHMP (2012) guidelines. The accuracy of the later waves is limited by the accuracies of the bathymetry and coastline that are outside the extent of the high-resolution DEM but still impact the modeling. Finally, we mention that the horizontal resolution of the highest resolution grid that was used for inundation modeling is about 16 m (53 ft). This resolution is high enough to describe major relief features, but small topographic features, buildings, and other facilities cannot be resolved accurately by the existing model.

  3. How accurate are the heights or depths?

    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.

  4. Where are the gaps in the data? What is missing?

    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 and actual conditions during a tsunami event may vary from those considered.

  5. How consistent are the relationships among the observations, including topology?

    Model validation for this report included comparison of the modeled results to observations that were recorded during historic events.

How can someone get a copy of the data set?

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.

  1. Who distributes the data set? (Distributor 1 of 1)

    Alaska Division of Geological & Geophysical Surveys
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (<http://www.dggs.alaska.gov>) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set?

    RI 2016-8

  3. What legal disclaimers am I supposed to read?

    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.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Dec-2016
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Metadata Manager
3354 College Road
Fairbanks, AK 99709-3707
USA

(907)451-5020 (voice)

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.21 on Wed Feb 8 15:04:23 2017