Alaska Survey & Mapping Conference 08

Slide 1: GIS in Alaska Tsunami Inundation Modeling Dave West Alaska Earthquake Information Center Geophysical Institute University of Alaska Fairbanks

Slide 2: Alaska Inundation Mapping Partners Alaska Earthquake Information Center at the Geophysical Institute, UAF: http://www.aeic.alaska.edu Alaska Division of Geological & Geophysical Surveys: http://wwwdggs.dnr.state.ak.us Alaska Division of Homeland Security and Emergency Management: http://www.ak-prepared.com NOAA Center for Tsunami Research: http://nctr.pmel.noaa.gov/ Arctic Region Supercomputing Center: http://www.arsc.edu/ United State Geological Survey: http://alaska.usgs.gov/

Slide 3: Tsunami Hazard in Alaska The Alaska coastline has the greatest tsunami potential in the United States. The Great Alaska earthquake of March 28, 1964, generated a major tectonic tsunami (25 fatalities) and about 20 local landslide tsunamis (81 fatalities). Alaska coastal rivers drain nearby glaciers which deposit sediment into the heads of the fjords at a very high rate, leading to dangerous submarine landslide potential. •Comprehensive tsunami inundation mapping in Alaska requires an understanding of both tectonic and landslide tsunami potential for many coastal communities.

Slide 4: Our Mapping Process Numerical Wave Run-up Modeling Data preparation Model verification with field observations (i.e. 1964 tsunami) Identify Likely Tsunami Scenarios Inundation maps and report

Slide 5: Kodiak Inundation Map Computed and observed inundation limits at Kodiak Kodiak Video Waves inundating the Kodiak Naval Station in 1964, between 1 to 4 hours after the earthquake. Animation by Roger Edberg (ARSC) and Elena Suleimani (GI).

Slide 6: Seward, Resurrection Bay, AK Seward Gulf of Alaska

Slide 7: 1964 Inundation Photos: U.S. Army Corps of Engineers. Mosaic: USGS.  Seward was the only town hit by both landslide- and tectonically generated tsunami waves following the 1964 EQ.  Initial 7m-high wave within first 2 minutes, then a 10m-high tectonic wave 30 minutes later, covered with burning oil. Remains of old Seward waterfront, now home to an RV park.

Slide 8: Geological Setting Fjord head delta Lowell Cr. Fan delta Forth of July Cr. Fan delta Blocky debris Spruce Cr. Fan delta

Slide 9: The Seward slide of 1964 • Three separate landslides occurred around the city of Seward during 1964 earthquake. • The largest landslide removed a strip of land as wide as 400 feet along the Seward waterfront, together with docks and other harbor facilities. Outline of the landslide debris that slid during the 1964 earthquake. slide Seward waterfront, now waves home to an RV park.

Slide 10: Bathymetry data analysis  Question: Yellows and reds = Was there more than one slide? depth decrease  Data sources available: Blues = depth – 2001 NOAA multibeam survey increase – 6906 soundings from 8 NOAA surveys, 1905-1961 – 10,991 soundings from 1965 survey – 157 km of “chirp” high-resolution seismic reflection data  Bathymetry pre- and post-1964 compared to develop the bathymetric Bathtub differences map  Initial slide thicknesses were calculated throughout the bay where depth was greater post-1964, indicating where material had moved

Slide 11: Major slide complexes and their volumes Slide Volumes: x106 m3 1 3 1. Seward downtown 27.5 Seward 2. Lowell Point 18.1 4 4th of July Point 2 5 3. Resurrection river delta 2.9 Lowell 4. 4th of July Point 35.0 Point 5. Middle bay 40.7 Tonsina 6. Tonsina Point 16.8 Point 6 7. West shore 15.3 8 8. East shore 4.5 7 Bathtub Thumb Cove 9. Thumb Cove 16.5 9 10. South slope 33.3 slides waves Total: 210.6 Slide Thicknesses and outlines reference: 10 P.J. Haeussler et. al. 2007. Submarine slope failures near Seward, Alaska, during the M9.2 1964 earthquake. In:"Submarine Mass Movements and their consequences", V. Lykousis and D. Sakellariou and J. Locat (eds.), pp. 269-278

Slide 12: Inundation Maps

Slide 13: Cartographic Ouput

Slide 14: Challenges of Alaska Inundation Mapping • Lack of adequate digital bathymetric and topographic data for many Alaskan coastal communities; • Large changes in water depths and land elevations caused by the 1964 earthquake and other events; • Irregular shoreline; • Large tidal ranges • Lack of good metadata and benchmark info for incoming data • Troublesome intertidal range Lowell Point, Resurrection Bay

Slide 15: Problematic Intertidal Data • Given the reality of tides and affordable data collection methods, it is very difficult to get reliable elevation data for about 5m above high tide to 20m below. • Not covered in most aerial flyovers or bathymetric surveys, and LIDAR only covers if when flown at extreme low tide. • Particularly important for tsunamis, as this is often the range which most clearly demarcates what populations and infrastructure are at risk.

Slide 16: Tidal Zone Gap Interpolation 1/2 kilometer

Slide 17: Advantages of using GIS in Tsunami Modeling • Best facilitates data exchange between most geo-spatial organizations: academic, local, federal, etc… • Pre-assembled set of tools to efficiently complete the most repetitive processes • Cartographic output vastly superior to other solutions • Workflow and documentation integrated and transferable •Extensions (3D, Spatial, etc…) provide many of the same analytical capabilities as scientific software, without scripting • Seamless integration of models with local infrastructure data •Straightforward export to distributable formats such as .kml

Slide 18: GIS Information Distribution •Ultimate goal of tsunami research is saving lives and infrastructure •Education and straightforward information sharing most vital step in preparedness •Often simply making data available is not enough, user-friendly and interactive tools are needed •Most direct desktop GIS applications cost money and require too much training to depend on widespread use •GIS data development provides for easier use of web-based tools and free viewers: •Little or no training required •Functionality specific to use •Designed to present relevant information quickly and efficiently •Advantages and different levels of investment involved in each ESRI’s ArcReader Virtual Globe Viewers Custom Web GIS Development (Google Earth, NASA’s Worldwind, etc…) (ArcGIS Server, etc…)