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Volcanic
Volcanic eruptions are most likely to occur in the Pacific Rim states, which include Oregon. Although most volcanic hazards are triggered by an eruption, some hazards can occur when a volcano is quiet, such as an earthquake. The danger area around a volcano covers approximately a 20-mile radius, although there is some danger to people within 100 miles or more. Airborne ash from a volcano can affect people hundreds of miles away from the eruption. The most common volcano-related hazards are ash (tephra), lahars, lava and debris flows, avalanches, and pyroclastic flows.
Oregon’s vulnerability to volcanic events varies statewide. The Cascade Mountains, which separate Western Oregon from Central Oregon, poses the greatest threat for volcanic activity. Those regions that include the Cascade Mountains are most vulnerable to the effects of a volcanic event. Within the State of Oregon, there are several volcanoes that may pose a threat of eruption; these include Mount Hood, which most recently erupted about 200 years ago, the Three Sisters, and Mt. Jefferson, which has not erupted for about 15,000 years, but is not considered to be extinct. Deschutes County is most vulnerable in the Central Oregon Region because the region’s most populous city, Bend, is located here and the greatest numbers of “composite” volcanic mountains are located near the county’s population centers. Klamath and Jefferson counties are also vulnerable within this region. Other regions are also vulnerable to damage from volcanic eruptions. If Mt. Hood erupted, the Northern Willamette Valley/Portland Metro Region and the Mid-Columbia Region would both be impacted. Because of Mt. Hood’s proximity to Portland, the Columbia River, the I-84 freeway, and major dams on the Columbia River, the potential for a large disaster exists.
Back to index Maintained by: Oregon Partnership for Disaster Resilience Community Service Center University of Oregon Last Updated 07/02/2007 |
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This web page broadly identifies and describes the volcanic hazard that Oregon faces. It also highlights previous plans, assessment tools, and resources that have been developed to identify, profile, and assess the vulnerability and risk from volcanic events in Oregon.