Tsunami inundation maps of Elfin Cove, Gustavus, and Hoonah, Alaska

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What does this data set describe?

Title:
Tsunami inundation maps of Elfin Cove, Gustavus, and Hoonah, Alaska
Abstract:
In this report, we evaluate potential tsunami hazards for southeastern Alaska communities of Elfin Cove, Gustavus, and Hoonah and numerically model the extent of inundation from tsunami waves generated by tectonic and landslide sources. We perform numerical modeling of historic tsunami events, such as the tsunami triggered by the 1964 Great Alaska Earthquake, and the tsunami waves generated by the recent 2011 Tohoku and 2012 Haida Gwaii earthquakes. Hypothetical tsunami scenarios include variations of the extended 1964 rupture, megathrust earthquakes in the Prince William Sound and Alaska Peninsula regions, and a Cascadia megathrust earthquake. Local underwater landslide events in Taylor Bay and Port Frederick, and a rockslide in Tidal Inlet are also considered as possible tsunamigenic scenarios. Numerical modeling results, combined with historical observations in the region, are intended to provide guidance to local emergency management in tsunami hazard assessment, evacuation planning, and public education for the reduction of future tsunami risk.
Supplemental_Information:
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.
coastline:    Digitized MHHW (Mean Higher High Water) coastline of each community.
  1. How should this data set be cited?

    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.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -136.422607
    East_Bounding_Coordinate: -135.392487
    North_Bounding_Coordinate: 58.474888
    South_Bounding_Coordinate: 58.083485

  3. What does it look like?

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

    Beginning_Date: 2013
    Ending_Date: 2015
    Currentness_Reference: ground condition

  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?

    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 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.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean Higher High Water
      Depth_Resolution: 100
      Depth_Distance_Units: centimeters
      Depth_Encoding_Method: Attribute values

  7. How does the data set describe geographic features?

    ri2015-1-border.shp
    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)

    ri2015-1-max-inundation-line-elfincove.shp, ri2015-1-max-inundation-line-gustavus.shp ri2015-1-max-inundation-line-hoonah.shp
    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. File format: shapefile (Source: Alaska Earthquake Center, Geophysical Institute, University of Alaska, this report)

    ri2015-1-max-flow-depth-elfincove.tif, ri2015-1-max-flow-depth-gustavus.tif ri2015-1-max-flow-depth-hoonah.tif
    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)

    ri2015-1-coastline-elfincove.shp, ri2015-1-coastline-gustavus.shp ri2015-1-coastline-hoonah.shp
    Digitized MHHW (Mean Higher High Water) coastline of each community. 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 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 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 Chris Waythomas and Isaac Fine for their reviews that improved the report and maps.

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

    Alaska Division of Geological & Geophysical Surveys
    GIS Manager
    3354 College Road
    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?

The presented results presented 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.


How was the data set created?

  1. From what previous works were the data drawn?

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

    Date: 2014 (process 1 of 6)
    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 tectonic and landslide tsunami sources to Elfin Cove, Gustavus, and Hoonah. 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 Table 1 of 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: 2014 (process 2 of 6)
    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 Methodology and Data section of the accompanying report for more detail and additional model information.

    Date: 2014 (process 3 of 6)
    Model verification - We verified the numerical model by comparing results of the inundation modeling with observations collected from the Tohoku 2011 and Haida Gwaii 2012 tsunamis. First, we simulated the tectonic tsunami in Elfin Cove, Gustavus, and Hoonah using an output of a coseismic deformation model of each of the earthquake as an initial condition for water waves. Then we compared the modeled time series with the tsunami wave history recorded by the Elfin Cove tide gauge. See Methodology and Data and Modeling Results sections of the accompanying report for more detail and additional model information.

    Date: 2014 (process 4 of 6)
    Numerical simulations of hypothetical tsunami scenarios - We assessed hazard related to tectonic tsunamis in Elfin Cove, Gustavus, and Hoonah 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 Modeling Results section of the accompanying report for more detail and additional information.

    Date: 2014 (process 5 of 6)
    Compilation of maximum inundation zone and maximum flow depths - We calculated 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 Modeling results section of the accompanying report for more detail and additional information.

    Date: 2014 (process 6 of 6)
    Calculation of the potential inundation lines - For each grid cell in the high-resolution DEMs Elfin Cove, Gustavus, and Hoonah, 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.

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

    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
    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
    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
    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:

    Other_Citation_Details: 50 p
    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:

    Other_Citation_Details: 28 p., 2 sheets, scale 1:12,500
    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:

    Other_Citation_Details: 16 p., 4 sheets, scale 1:12,500
    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
    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


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. It has received technical review by several scientists familiar with the subject matter. 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. 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. The modeling process is highly sensitive to errors when the complexity of the source function is combined with its proximity to the coastal zone. The horizontal resolution of the grid used for inundation modeling is about 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 accompanying report.

  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. 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?

    Southeast Alaska has a long record of tsunami waves generated by submarine and subaerial landslides, avalanches, and rockfalls. We consider several hypothetical slope failure scenarios that could generate waves that could be potentially hazardous to the communities of Elfin Cove, Gustavus, and Hoonah. Unfortunately, there is no geotechnical information to constrain the locations and thicknesses of these potential underwater slides. Uncertainties are associated with geometry and configuration of potential landslides and rockfalls. Parameters of the hypothetical slides are listed in table 3 (of the manuscript) and discussed in more detail.

  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 2015-1

  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: 17-Apr-2015
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:


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