Tsunami inundation maps of Sitka, Alaska

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What does this data set describe?

Title: Tsunami inundation maps of Sitka, Alaska
Abstract:
The purpose of this study is to evaluate potential tsunami hazards for the community of Sitka. We numerically modeled the extent of inundation from tsunami waves generated by near- and far-field tectonic sources. We performed numerical modeling of historic events at Sitka, 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 Alaska Peninsula region and in the Cascadia subduction zone, and a thrust earthquake in the region of the Queen Charlotte-Fairweather fault zone. Results of numerical modeling 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:
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:
mhhw-shoreline:    The present day shoreline (mean higher high water - MHHW) of the Sitka study area; see Grid Development and Data Sources section of this report to learn more about how this file was created. 
hypothetical-composite-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. 
hypothetical-composite-flow-depth:    Raster image depicting maximum composite flow depths over dry land. 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.
tectonic-scenario-01:    Scenario 1. Multi-Segment event based on the JDM (PWS, KP, KI, and YY segments) 
tectonic-scenario-02:    Scenario 2. Multi-Segment event based on the SDM (PWS, KP, KI, and YY segments) 
tectonic-scenario-03:    Scenario 3. Modified multi-segment event: rupture of the PWS, KP, and YY segments of the JDM 
tectonic-scenario-04:    Scenario 4. Modified multi-segment event: rupture of the PWS, KP, and YY segments of the SDM 
tectonic-scenario-05:    Scenario 5. Multi-Segment event: the Tohoku-type rupture of the PWS, KP and KI segments 
tectonic-scenario-06:    Scenario 6. The SAFRR tsunami scenario (SEM and SH segments) >tectonic-scenario-07:    Scenario 7. Rupture in the Eastern Aleutians, from Semidi Islands to Fox Islands (SEM, SH, UN and FOX segments) 
tectonic-scenario-08:    Scenario 8. Rupture on the Cascadia subduction zone >tectonic-scenario-09:    Scenario 9. Mw8.2 thrust earthquake in the Haida Gwaii area
  1. How should this data set be cited?

    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.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -135.518143
    East_Bounding_Coordinate: -135.212479
    North_Bounding_Coordinate: 57.146736
    South_Bounding_Coordinate: 57.021259

  3. What does it look like?

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

    Calendar_Date: 2013
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: digital data, report, map sheet

  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?

      The horizontal datum used is World Geodetic System of 1984.
      The ellipsoid used is World Geodetic System of 1984.
      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: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    ri2013-3-mhhw-shoreline
    The present day shoreline (mean higher high water - MHHW) of the Sitka study area; see Grid Development and Data Sources section of this report to learn more about how this file was created. File format: shapefile (Source: U.S. Geological Survey and University of Alaska Fairbanks)

    ri2013-3-hypothetical-composite-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. File format: shapefile (Source: This report)

    ri2013-3-hypothetical-composite-flow-depth
    Raster image 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: This report)

    ri2013-3-tectonic-scenario-01
    Scenario 1. Multi-Segment event based on the JDM (PWS, KP, KI, and YY segments) File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-02
    Scenario 2. Multi-Segment event based on the SDM (PWS, KP, KI, and YY segments) File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-03
    Scenario 3. Modified multi-segment event: rupture of the PWS, KP, and YY segments of the JDM File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-04
    Scenario 4. Modified multi-segment event: rupture of the PWS, KP, and YY segments of the SDM File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-05
    Scenario 5. Multi-Segment event: the Tohoku-type rupture of the PWS, KP and KI segments File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-06
    Scenario 6. The SAFRR tsunami scenario (SEM and SH segments) File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-07
    Scenario 7. Rupture in the Eastern Aleutians, from Semidi Islands to Fox Islands (SEM, SH, UN and FOX segments) File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-08
    Scenario 8. Rupture on the Cascadia subduction zone File format: shapefile (Source: This report)

    ri2013-3-tectonic-scenario-09
    Scenario 9. Mw8.2 thrust earthquake in the Haida Gwaii area File format: shapefile (Source: 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 grants 27-014d and 06-028a through the Cooperative Institute for Arctic Research. 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 as part of the US Department of Defense HPC Modernization Program. We thank Dr. Lucinda Leonard and an anonymous reviewer for their thoughtful reviews of the draft manuscript 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?

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 Sitka 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?

    Hickman, P.J. and others, 2012 (source 1 of 5)
    Hickman, P.J., Suleimani, E.N., and Nicolsky, D.J., 2012, Digital elevation model of Sitka Harbor and the city of Sitka, Alaska: Procedures, data sources, and quality assessment: Miscellaneous Publication MP 144, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 38 p
    Type_of_Source_Media: raster
    Source_Contribution: development of nested grids

    Lim, E. and others, 2011 (source 2 of 5)
    Lim, E., Eakins, B.W., and Wigley, R., 2011, Coastal relief model of southern Alaska: Procedures, data sources and analysis: NOAA Technical Memorandum NESDIS NGDC-43, National Geophysical Data Center, Marine Geology and Geophysics Division, United States.

    Type_of_Source_Media: raster
    Source_Contribution: development of nested grids

    Nicolsky, D.J and others, 2011 (source 3 of 5)
    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 validation

    NOAA/NWS, 2012 (source 4 of 5)
    NOAA/NWS, 2012, National Tsunami Warning Center: National Oceanic and Atmospheric Administration, United States.

    Type_of_Source_Media: database
    Source_Contribution: model verification

    NOAA/WDS, 2012 (source 5 of 5)
    NOAA/WDS, 2012, Tsunami Event Database: National Oceanic and Atmospheric Administration, United States.

    Type_of_Source_Media: database
    Source_Contribution: model verification

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

    Date: 2011 (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 both distant and local sources to Sitka. 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 Sitka mapping is listed in table 1 of the manuscript. See Methodology and data section of the associated manuscript for more detail and additional data source information.

    Data sources used in this process:

    • Hickman, P.J. and others, 2012
    • Lim, E. and others, 2011

    Date: 2011 (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 associated manuscript for more detail and additional model information.

    Data sources used in this process:

    • Nicolsky, D.J and others, 2011

    Date: 2012 (process 3 of 6)
    Model verification - We examined the tsunami effects at Sitka from the most significant earthquakes of the last century. For model verification, we chose the 1964 Alaska tsunami because it generated the highest recorded wave at Sitka, while the Tohoku 2011 and the Haida Gwaii 2012 events represent the far- and near-field tsunami sources, respectively, with different directional properties. We verified the numerical model by comparing results of the inundation modeling with observations collected shortly after the event. First, we simulated the tectonic tsunami in Sitka using an output of a coseismic deformation model of each of the earthquakes as an initial condition for water waves. Then we compared the modeled inundation zones with the observed extent of inundation. See Methodology and data and Modeling results sections of the associated manuscript for more detail and additional model information.

    Data sources used in this process:

    • NOAA/NWS, 2012
    • NOAA/WDS, 2012

    Date: 2012 (process 4 of 6)
    Numerical simulations of hypothetical tsunami scenarios - We assessed hazard related to tectonic tsunamis in Sitka by performing model simulations for each hypothetical earthquake source scenario. Numerical results for each scenario include extent of inundation, sea level and velocity time series, and tsunami flow depth. See Modeling results section of the associated manuscript for more detail and additional information.

    Date: 2012 (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 associated manuscript for more detail and additional information.

    Date: 2012 (process 6 of 6)
    Calculation of the potential inundation lines - For each grid cell in the high-resolution DEM of Sitka, 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., 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., 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
    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


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. Landslide tsunami sources are not included in the current study due to unknown potential impact of such events on Sitka. The limits of inundation shown should only be used as a guideline for emergency planning and response action. Actual areas inundated will depend on specifi cs 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 and Uncertainties 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 extent of tsunami inundation was calculated through numerical modeling of water waves over bathymetry and topography. To efficiently compute a detailed map of potential tsunami inundation, we employed a series of nested computational grids. A nested grid allows for higher resolution in areas where it is needed, without expending computer resources in areas where it is not. The computational grid was based on digital elevation models (DEMs) obtained from various U.S. federal and academic agencies. The highest level of horizontal resolution of the grid used for inundation modeling is about 15 m (49 ft). This scale is mostly limited by the computational resources necessary to compute the tsunami inundation at the higher resolution. The 15 m (49 ft) 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. For additional information please reference the Grid Development and Data Sources section of the associated manuscript.

  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?

    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. Southeast Alaska has a long record of tsunami waves generated by submarine and subaerial landslides, avalanches, and rock falls. While we acknowledge that communities in southeastern Alaska are considered at risk from locally generated waves because of their proximity to landslide-prone fjords in a seismically active zone, we did not quantify this category of landslide tsunami hazard for Sitka 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?

    Results of numerical modeling were verified by simulating historic tsunamis. 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 2013-3

  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: 02-Dec-2013
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 Dec 2 13:17:07 2013