Tsunami hazard maps of the Homer and Seldovia areas, Alaska

Metadata also available as - [Parseable text] - [XML]

Frequently anticipated questions:


What does this data set describe?

Title: Tsunami hazard maps of the Homer and Seldovia areas, Alaska
Abstract:
The purpose of this study was to evaluate a potential tsunami risk for communities of Homer and Seldovia in the Kachemak Bay area, Alaska. This report provides guidance to the local emergency managers in tsunami hazard assessment. We used a numerical modeling method to estimate the extent of inundation due to tsunami waves generated by earthquake sources. Our tsunami scenarios included a repeat of the tsunami of the 1964 great Alaska earthquake, as well as a hypothetical tsunami wave generated by a local fault source. We didn't consider landslide-generated tsunamis in this study. Results of numerical modeling combined with historical observations in the region are intended to help local emergency services officials with evacuation planning and public education for reducing risk from future tsunamis.
Supplemental_Information:
The DGGS metadata standard extends the FGDC standard to include elements that are required to facilitate our internal data management. These elements, referred to as "layers," group and describe files that have intrinsic logical or topological relationships and correspond to subdirectories within the data distribution package. The metadata layer provides the metadata or other documentation files. Attribute information for each data layer is described in this metadata file under the "Entity_and_Attribute_Information" section. Data layer contents:
homer-hypothetical-composite-line:    Estimated, "maximum credible scenario" inundation line that encompasses the maximum extent of flooding in the vicinity of Homer. It is 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.
homer-tectonic-scenario-01:    Homer - inundation line derived from modeled repeat of 1964 event
homer-tectonic-scenario-01-depth:    Homer - inundation depths derived from modeled repeat of 1964 event
homer-tectonic-scenario-02:    Homer - inundation line derived from modeled-hypothetical Border Ranges fault rupture
homer-tectonic-scenario-02-depth:    Homer - inundation depths derived from modeled-hypothetical Border Ranges fault rupture
homer-time-history-points:    Homer - point locations of the velocity and sea level time series diagrams presented in the report
seldovia-hypothetical-composite-line:    Estimated, "maximum credible scenario" inundation line that encompasses the maximum extent of flooding in the vicinity of Seldovia. It is 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.
seldovia-tectonic-scenario-01:    Seldovia - inundation line derived from modeled repeat of 1964 event
seldovia-tectonic-scenario-02:    Seldovia - inundation line derived from modeled-hypothetical Border Ranges fault rupture
seldovia-time-history-points:    Seldovia - point locations of the velocity and sea level time series diagrams presented in the report
  1. How should this data set be cited?

    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.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -151.781459
    East_Bounding_Coordinate: -151.406338
    North_Bounding_Coordinate: 59.667363
    South_Bounding_Coordinate: 59.391867

  3. What does it look like?

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

    Calendar_Date: 2005
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: digital-data, report, maps

  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 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in decimal degrees.

      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is North American Datum of 1927.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.9786982.

      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?

    ri2005-2-homer-hypothetical-composite-line
    Estimated, "maximum credible scenario" inundation line that encompasses the maximum extent of flooding in the vicinity of Homer. It is 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: This report)

    ri2005-2-homer-tectonic-scenario-01
    Homer - inundation line derived from modeled repeat of 1964 event; File format: shapefile (Source: This report)

    ri2005-2-homer-tectonic-scenario-01-depth
    Homer - inundation depths derived from modeled repeat of 1964 event; File format: shapefile (Source: This report)

    DEPTH_CM
    depth of inundation (Source: This report)

    Range of values
    Minimum:1.043
    Maximum:545.218994
    Units:centimeters

    ri2005-2-homer-tectonic-scenario-02
    Homer - inundation line derived from modeled-hypothetical Border Ranges fault rupture; File format: shapefile (Source: This report)

    ri2005-2-homer-tectonic-scenario-02-depth
    Homer - inundation depths derived from modeled-hypothetical Border Ranges fault rupture; File format: shapefile (Source: This report)

    DEPTH_CM
    depth of inundation (Source: This report)

    Range of values
    Minimum:1.607
    Maximum:623.606995
    Units:centimeters

    ri2005-2-homer-time-history-points
    Homer - point locations of the velocity and sea level time series diagrams presented in the report; File format: shapefile (Source: This report)

    POINT
    Label assigned to each location point (Source: This report)

    Range of values
    Minimum:1
    Maximum:6

    ri2005-2-seldovia-hypothetical-composite-line
    Estimated, "maximum credible scenario" inundation line that encompasses the maximum extent of flooding in the vicinity of Seldovia. It is 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: This report)

    ri2005-2-seldovia-tectonic-scenario-01
    Seldovia - inundation line derived from modeled repeat of 1964 event; File format: shapefile (Source: This report)

    ri2005-2-seldovia-tectonic-scenario-02
    Seldovia - inundation line derived from modeled-hypothetical Border Ranges fault rupture; File format: shapefile (Source: This report)

    ri2005-2-seldovia-time-history-points
    Seldovia - point locations of the velocity and sea level time series diagrams presented in the report; File format: shapefile (Source: This report)

    POINT
    Label assigned to each location point (Source: This report)

    Range of values
    Minimum:1
    Maximum:5


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, National Tsunami Hazard Mitigation Program, through grant NA17RJ1224. The authors wish to thank Dr. Fumihiko Imamura for the Fortran code of the Okada algorithm he kindly provided. We also thank Dr. George R. Priest and Dr. Jose Borrero for their thoughtful reviews of the draft manuscript and maps, and Dr. Natalia Ratchkovsky for the review of the seismicity analysis. For a complete list of data sources for the bathymetric and topographic grids, see the ACKNOWLEDGMENTS section of the report.

  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?

Large seismic events occurring in the vicinity of the Alaska Peninsula, Aleutian Islands, and Gulf of Alaska have a very high potential for generating both local and Pacific-wide tsunamis. Saving lives and property depends on how well a community is prepared, which makes it essential to estimate the potential flooding of the coastal zone in the case of a local or distant tsunami. The Alaska Tsunami Mapping Team (ATMT) participates in the National Tsunami Hazard Mitigation Program (NTHMP) by evaluating and mapping potential inundation of selected parts of the Alaska coastline using numerical modeling of tsunami wave dynamics. The communities are selected for inundation modeling in coordination with the Division of Homeland Security and Emergency Management (DHSEM) with consideration for location, infrastructure, availability and quality of bathymetric and topographic data, and community involvement. The tsunami inundation maps described in the associated manuscript represent the results of the continuous effort of state and federal agencies to produce inundation maps for many Alaska coastal communities.


How was the data set created?

  1. From what previous works were the data drawn?

    Johnson, J.M. and others, 1996 (source 1 of 5)
    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.

    Type_of_Source_Media: paper
    Source_Contribution: numerical modeling of tsunami wave runup

    Kowalik, Z. and Murty, T.S., 1993 (source 2 of 5)
    Kowalik, Z., and Murty, T.S., 1993, Numerical simulation of two-dimensional tsunami runup: Canadian Bulletin of Fisheries and Aquatic Sciences v.16, Taylor & Francis, Inc., Philadelphia, PA.

    Type_of_Source_Media: paper
    Source_Contribution: numerical modeling of tsunami wave runup

    Murty, T.S., 1984 (source 3 of 5)
    Murty, T.S., 1984, Storm surges - meteorological ocean tides: Canadian Bulletin of Fisheries and Aquatic Sciences v.212, National Research Council of Canada, Canada.

    Type_of_Source_Media: paper
    Source_Contribution: numerical modeling of tsunami wave runup

    Reid, R.O and Bodine, B.R., 1968 (source 4 of 5)
    Reid, R.O, and Bodine, B.R., 1968, Numerical model for storm surges in Galveston Bay: Journal of the Waterways and Harbors Division v.94, no. WWI, National American Society of Civil Engineers, Reston, VA.

    Type_of_Source_Media: paper
    Source_Contribution: numerical modeling of tsunami wave runup

    Troshina, E.N., 1996 (source 5 of 5)
    Troshina, E.N., 1996, Tsunami waves generated by Mt. St. Augustine volcano, Alaska: University of Alaska Fairbanks, Fairbanks, AK.

    Type_of_Source_Media: paper
    Source_Contribution: numerical modeling of tsunami wave runup

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

    Date: 2005 (process 1 of 1)
    Numerical modeling of tsunami wave runup - We calculated the extent of inundation caused by tsunami waves using numerical modeling of tsunami wave runup. The model is based on the vertically integrated nonlinear shallow water equations of motion and continuity with friction and Coriolis force (Murty, T.S., 1984). We applied a space-staggered grid, which requires either sea level or velocity as a boundary condition. The first order scheme is applied in time and the second order scheme is applied in space. Integration was performed along the north-south and west-east directions separately (as described by Kowalik, Z. and Murty, T.S., 1993). In order to propagate the wave from a source to various coastal locations we used embedded grids, placing a coarse grid in deep water and coupling it with finer grids in shallow water areas. We used an interactive grid splicing, therefore the equations are solved on all grids at each time step, and the values along the grid boundaries are interpolated at the end of every time step (Troshina, E.N., 1996). The radiation condition was applied at the open ocean boundaries (Reid, R.O and Bodine, B.R., 1968). At the water-land boundary, the moving boundary condition was used in those grids that cover areas selected for inundation mapping (as described by Kowalik, Z. and Murty, T.S., 1993). In all other grids, the velocity component normal to the coastline was assumed to be zero. The Center for Tsunami Inundation Mapping Efforts, Pacific Marine Environmental Laboratory (NOAA/PMEL/TSUNAMI/TIME) was primarily responsible for developing the bathymetric and topographic grids for this modeling project. Bathymetry was adequate but the existing USGS topographic data was found to be insufficient for accurate modeling. Newer topographic data for Homer, in the form of a recently acquired LIDAR survey, was located and included in the dataset for this study. The newer topographic dataset has a resolution of approximately 1.4 meter grid spacing with close to 0.3 meter vertical accuracy, and greatly improved the accuracy of our modeling results over the USGS dataset. We considered two hypothetical earthquake scenarios as potential sources of tsunami waves that can affect Homer and Seldovia. Scenario 1, Repeat of the 1964 event, 17 sub-faults as modeled by Johnson and others (1996); and Scenario 2, a hypothetical Border Ranges fault rupture. These scenarios are described in detail in the text of the report. The basic steps in our modeling efforts were as follows: 1) use each scenario to estimate the displacement of water as an initial condition for the wave modeling; 2) use the shallow water equations and the embedded bathymetry/topography grids to model the movement of water caused by this initial condition; 3) use the moving boundary condition to estimate the extent of inundation in the regions of highest risk to people/infrastructure ; 4) analyze the results of modeling, compare to historical accounts of similar events; and 5) construct tsunami hazard maps for mitigation purposes. For more detailed description of processing steps and analysis see the text report included with these digital files.

    Data sources used in this process:

    • Johnson, J.M. and others, 1996
    • Kowalik, Z. and Murty, T.S., 1993
    • Murty, T.S., 1984
    • Reid, R.O and Bodine, B.R., 1968
    • Troshina, E.N., 1996

  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
    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 presented maps have been completed using the best information available and are believed to be accurate; however, their preparation required many assumptions. We have considered several tsunami scenarios and have provided 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 only be used as a guideline for emergency planning and response action. 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 information on this map 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. Users should review the accompanying report, particularly the Sources of Errors section, for a detailed discussion of limitations of the methods used to generate the various inundation models.

  2. How accurate are the geographic locations?

    The computational grid was based on digital elevation models (DEMs) obtained from various agencies. The highest level of horizontal resolution of the grid used for inundation modeling is about 15 m relative to the grid spacing. The 15 m resolution is high enough to describe major relief features, but small topographic features, buildings, and other facilities cannot be accurately resolved by the existing model. The associated manuscript provides additional information about the numerical model and underlying grids.

  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.

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

    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 fjords of coastal Alaska and other high-latitude fjord coastlines. We did not quantify this category of landslide tsunami hazard in the current report due to poor constraints on the parameters of potential slides, such as locations, volumes, and geotechnical properties.

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

    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.


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 2005-2

  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: 06-Jan-2014
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 Mon Jan 6 11:39:53 2014