Potential maximum permanent flooding maps for Unalaska and Akutan, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
Potential maximum permanent flooding maps for Unalaska and Akutan, Alaska
Abstract:
This digital data distribution package provides post-earthquake shorelines for coastal areas near Unalaska and Akutan, Alaska that become permanently flooded due to coseismic subsidence. Users can access the data, as well as additional metadata, from the DGGS website: <http://doi.org/10.14509/29728>.
Supplemental_Information:
post-earthquake-shoreline: The post-earthquake shoreline that corresponds to MHHW after modeled coseismic ground changes due to earthquakes.
  1. How should this data set be cited?

    Nicolsky, D.J., Suleimani, E.N., Freymueller, J.T., and Koehler, R.D., 2017, Potential maximum permanent flooding maps for Unalaska and Akutan, Alaska: Report of Investigation RI 2015-5A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 2 sheets

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -166.659760
    East_Bounding_Coordinate: -165.700483
    North_Bounding_Coordinate: 54.157923
    South_Bounding_Coordinate: 53.810076

  3. What does it look like?

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

    Calendar_Date: 2017
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: raster

  6. How does the data set represent geographic features?

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

      This is a raster 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 0.00001. Longitudes are given to the nearest 0.00001. 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 1/298.257223563000025.

  7. How does the data set describe geographic features?

    ri2015-5a-post-earthquake-shoreline-akutan.tif, ri2015-5a-post-earthquake-shoreline-unalaska.tif
    The post-earthquake shoreline that corresponds to MHHW after modeled coseismic ground changes due to earthquakes. For each grid point, the pixel value provides the modeled depth of water (in meters) over previously dry land. File format: raster (Source: Alaska Earthquake Information 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 report was funded by a National Tsunami Hazard Mitigation Program grant to the Alaska Division of Homeland Security and Emergency Management and the University of Alaska Fairbanks from the Department of Commerce/National Oceanic and Atmospheric Administration. This does not constitute an endorsement by NOAA. Numerical calculations for this work were supported by High Performance Computing (HPC) resources at the Research Computing Systems unit at the Geophysical Institute, University of Alaska Fairbanks.

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

    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    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


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?

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

    Date: 2017 (process 1 of 1)
    To create a raster file for the coastal area that becomes permanently flooded due to coseismic subsidence, we calculated the amount of coseismic ground subsidence in the community for each scenario considered in the report and select the largest value among all scenarios. Using a Matlab code, we plotted the community DEM used to model tsunami inundation. Then we selected all DEM values between the largest value of subsidence and zero, which corresponds to the pre-earthquake coastline. We made a raster file that covers the selected DEM values and exported it as GeoTIFF file to be imported into ArcGIS.

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

    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


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. Actual conditions during a seismic event may vary from those considered, so the accuracy cannot be guaranteed. The limits of permanent flooding shown should be used only as a guideline for emergency planning and response action. Actual areas that may be permanently flooded will depend on specifics of the earth deformations, on-land construction, site-specific soil properties, 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 associated manuscript.

  2. How accurate are the geographic locations?

    Assumptions and uncertainties in the originating DEM, position of the MHHW shoreline, earthquake model, and other contributing factors influence the modeled shoreline position. Actual areas that may be permanently flooded will depend on specifics of the earth deformations, on-land construction, site-specific soil properties, and tide level, and they may differ from areas shown on the map. See accompanying report for additional discussion.

  3. How accurate are the heights or depths?

    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. The uncertainties in tsunami modeling include bottom friction, presence or absence of buildings and vegetation in DEMs, the time delay between the observed and computed tsunami arrivals discussed above, the lack of horizontal deformation in the displacement models, and assumption of instantaneous displacement. The tsunami scenarios that we calculate in this report are considered to be sufficient to capture the worst-case tsunami event, but there are still an infinite number of possible slip distributions. 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 the National Tsunami Hazard Mitigation Program 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. See accompanying report for more detail.

  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 &amp; 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
    Metadata Manager
    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
  2. What's the catalog number I need to order this data set?

    RI 2015-5A

  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: 12-Aug-2019
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
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
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Generated by mp version 2.9.21 on Mon Aug 12 16:49:08 2019