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Open-File Report O-23-01, Multi-Hazard Risk Report for Tillamook County, Oregon, including the cities of Bay City, Garibaldi, Manzanita, Nehalem, Rockaway Beach, Tillamook, and Wheeler and the unincorporated communities of Bayside Gardens, Neskowin, Oceanside, Netarts, and Pacific City, by Matt C. Williams and Nancy C. Calhoun; 111 p. report, 11 tabloid size map plates, one Esri® geodatabase with internal metadata, external metadata in .xml format.

What's in this report?
This report describes the methods and results of a natural hazard risk assessment for Tillamook County communities. The risk assessment can help communities better plan for disaster.

Report downloads:


This report was prepared for the communities of Tillamook County, Oregon, with funding provided by the Oregon Department of Land Conservation and Development (DLCD). It describes the methods and results of the natural hazard risk assessment performed in 2022 by the Oregon Department of Geology and Mineral Industries (DOGAMI) within the study area. The purpose of this project is to provide communities with detailed risk assessment information to enable them to compare hazards and act to reduce their risk. The risk assessment results quantify the impact of natural hazards to each community and enhance the decision-making process in planning for disaster.

We arrived at our findings and conclusions by completing three main tasks: compiling an asset database, identifying and using the best available hazard data, and performing natural hazard risk assessment.

The findings and conclusions of this report show the potential impacts of hazards to communities within Tillamook County. A Cascadia Subduction Zone (CSZ) event (earthquake and tsunami) will cause extensive damage and losses throughout the county. Our findings indicate that most of the study area’s critical facilities are at high risk during a CSZ event. We demonstrate the potential for the reduction in damages and losses from seismic retrofits through building code simulations in the Hazus-MH earthquake model. We also found that the hazards with the highest potential of population displacement are earthquake, tsunami, and landslide hazards. Flooding is a threat for some communities in the study area and we quantify the number of elevated structures that are less vulnerable to flood hazard. Our analysis shows that areas with moderate to steep slopes or at the base of steep hillsides are at greatest risk to landslide hazards, which are present throughout the communities and rural county. Over 1,200 buildings along the coast of Tillamook County were exposed to coastal erosion. Wildfire exposure analysis show a higher risk for buildings within the wildland-urban interface (WUI) portions of the county.

The information presented in this report is designed to increase awareness of natural hazard risk, to support public outreach efforts, and to aid local decision-makers in developing comprehensive plans and natural hazard mitigation plans. This study can help emergency managers identify vulnerable critical facilities and develop contingencies in their response plans. The results of this study are designed to be used to help communities identify and prioritize mitigation actions that will improve community resilience. This analysis improves on the 2020 DOGAMI natural hazard risk assessment, which relied on less accurate and outdated hazard and building data.

Results were broken out for the following geographic areas:

Selected Countywide Results
Total buildings: 27,090
Total estimated building value: $6.9 billion

Cascadia Subduction Zone
Magnitude-9.0 Earthquakea

Red-tagged buildings: 2,123
Yellow-tagged buildings: 5,541
Loss estimate: $1.5 billion

Cascadia Subduction Zone
Magnitude-9.0 Tsunami Inundation

Number of buildings damaged: 4,931
Loss estimate: $1 billion

Happy Camp Fault
Magnitude-6.6 Earthquake Scenario 

Red-tagged buildings: 1,136
Yellow-tagged buildings: 3,648
Loss estimate: $992 million

100-year Flood Scenario
Number of buildings exposed: 2,574
Loss estimate: $91 million

Landslide Exposure (High and Very High Susceptibility)
Number of buildings exposed: 9,690
Exposed building value: $2 billion

Coastal Erosion Exposure (Moderate Hazard) 
Number of buildings exposed: 1,227
Exposed building value: $280 million

Wildfire (High and Moderate Risk)
Number of buildings exposed: 657
Exposed building value: $136 million


aResults reflect damage caused by the earthquake to buildings outside of the tsunami zone. The combined earthquake and tsunami results estimate the total damage from a CSZ Mw-9.0 event.
bRed-tagged buildings are considered to be uninhabitable due to complete damage.
Yellow-tagged buildings are considered to be of limited habitability due to extensive damage.



Geodatabase is Esri® version 10.7 format.
Metadata is embedded in the geodatabases and is also provided as separate .xml format files.

Each dataset listed below has an associated, standalone .xml file containing metadata in the Federal Geographic Data Committee Content Standard for Digital Geospatial Metadata format.


Feature dataset: Asset_Data












APPENDIX E: MAP PLATES (PDFs, 17 x 11 inches each)

Plate 1, Building Distribution Map of Tillamook County, Oregon (6.8 MB PDF)

MapDescription automatically generated



Plate 2, Population Density Map of Tillamook County, Oregon (6.7 MB PDF)



Plate 3, CSZ Magnitude-9.0 Earthquake Shaking Map (PGA) of Tillamook County, Oregon (2.1 MB PDF)



Plate 4, Happy Camp Fault Magnitude-6.6 Earthquake Shaking (PGA) Map of Tillamook County, Oregon    (18.3 MB PDF)



Plate 5, Coseismic Landslide Susceptibility (Wet) Map of Tillamook County, Oregon (6.4 MB PDF)



Plate 6, Liquefaction Susceptibility Map of Tillamook County, Oregon (6.4 MB PDF)

Plate 7, Site Amplification Class Map of Tillamook County, Oregon  (6.6 MB PDF)


Plate 8, Tsunami Inundation Map of Tillamook County, Oregon  (7.6 MB PDF)


Plate 9, Flood Hazard Map of Tillamook County, Oregon  (7.2 MB PDF)



Plate 10, Landslide Susceptibility Map of Tillamook County, Oregon  (11.1 MB PDF)


Plate 11, Wildfire Risk Map of Tillamook County, Oregon  (11.1 MB PDF)