Lab 4: Tsunami Disaster Modeling and Recovery Planning
Introduction and Methods
Just off the coast of Oregon lies the Cascadia Subduction Zone, which is a 600 mile earthquake fault that runs from southern British Columbia to northern California. This subduction zone was created from the Juan de Fuca and Gorda plates converging and subduction beneath the North American plate. The Cascadia Subduction Zone is capable of producing an earthquake with a magnitude 9.0 or higher. Offshore earthquakes often produce tsunamis, a series of waves or surges. The following map shows the coastline of Lincoln County, Oregon in the event of a local tsunami, which are formed by long-duration, violent earthquakes less than 100 miles off the coast much like the anticipated “Big One” that could occur at any minute in the Cascadia Subduction Zone. Disaster preparedness, such as organizing suitable tsunami recovery zones, is crucial to withstanding and recovering from an earthquake and its subsequent tsunami as every dollar invested into preparing for natural disasters saves seven dollars in recovering from one.
Data Used in the Lab:
- Tsunami Inundation Zone (2013) – DOGAMI
- City Limits (2013) – ODOT
- Highways (2013) – ODOT
- Census Blocks with Demographic Data (2010) – U.S. Census Bureau
- Counties – ESRI, Tele Atlas North America, Inc., and Geographic Data Technology, Inc.
- Lincoln County Elevation Model (DEM) – University of Oregon
The purpose of this map is to show suitable areas to place tsunami recovery zones in Lincoln County, Oregon. In order to do this I had to complete a Euclidean distance analysis against the local tsunami inundation zone and highways to determine the areas that are outside yet still near the tsunami inundation and the areas near highways. I then reclassed these two pieces of data along with the Lincoln County DEM into ten classes with natural breaks (Jenks). Using the raster calculator I combined the three layers that I then manually reclassed into two classes, suitable and not suitable. Using the majority filter I filtered the reclass then converted the raster into a vector data set using the raster to polygon tool. Below you can see the final product of this analysis along with reference information, such as cities that are in or near the local tsunami inundation zone and county borders.
Below is the model builder I used to complete my analysis.
Potential Statewide Effects from a Local Tsunami
Following is the number of housing units and population summarized by county that are located within the local tsunami inundation zone.
| County | Housing Units | Population |
| Clatsop | 16,238 | 26,214 |
| Coos | 15,870 | 31,439 |
| Curry | 7,559 | 12,466 |
| Douglas | 2,099 | 3,637 |
| Lane | 3,858 | 5,499 |
| Lincoln | 20,856 | 26,872 |
| Tillamook | 11,842 | 12,290 |
Following is the area of city limits that are located within the local tsunami inundation zone.
| City | Area (ft^2) |
| Astoria | 284,243,879.89 |
| Bandon | 88,960,026.64 |
| Bay City | 53,898,194.18 |
| Brookings | 116,049,955.27 |
| Cannon Beach | 40,483,346.35 |
| Coos Bay | 449,025,955.70 |
| Coquille | 76,098,101.46 |
| Depoe Bay | 50,271,264.80 |
| Dunes City | 96,073,828.87 |
| Florence | 164,025,566.49 |
| Garibaldi | 37,176,767.10 |
| Gearhart | 50,545,982.61 |
| Gold Beach | 74,179,696.31 |
| Lakeside | 63,150,962.09 |
| Lincoln City | 166,883,439.75 |
| Manzanita | 22,666,920.45 |
| Nehalem | 7,700,199.00 |
| Newport | 582,480,384.85 |
| North Bend | 141,673,974.51 |
| Port Orford | 45,796,683.05 |
| Reedsport | 63,755,190.35 |
| Rockaway Beach | 43,858,940.73 |
| Seaside | 111,642,929.99 |
| Tillamook | 49,838,580.24 |
| Toledo | 65,028,614.70 |
| Waldport | 85,573,000.49 |
| Warrenton | 495,000,319.36 |
| Wheeler | 14,232,496.67 |
| Yachats | 26,027,428.51 |
Total length of highway in the inundation zone: 360.67 miles
Results
The whole coast of Oregon will be destroyed in the event of the “Big One”. This map and analysis have the potential to help Oregon, specifically the coastal area, prepare for a tsunami. Lincoln County in particular could truly benefit from the main portion of the map as it shows areas that are suitable for setting up recovery zones in the wake of a tsunami. More work needs to be done in these areas to truly prepare them for the impending disaster, such as relocating essential services, which will require more analyses such as this one.
References
“Living on Shaky Ground.” Oregon Geology. Oregon Department of Geology and Mineral Industries, n.d. Web.