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11,0 VOLCAN}C HAZARDS <br /> <br />11,1 Overview <br /> <br />The Cascades, which run from British Columbia through Washington and Oregon into <br />northern California, contain more than a dozen major volcanoes and hundreds of <br />smaller volcanic features. In the past 200 years, seven of the Cascade volcanoes in <br />the United States have erupted, including: Mt. Baker, Glacier Peak, Mt. Ranier, Mount <br />St. Helens, Mt. Hood, Mt. Shasta, and Mt. Lassen. <br /> <br />Over the past 4000 years (a geologically very short time period) in Oregon there have <br />been three eruptions of Mt. Hood, four eruptions in the Three Sisters area, and two <br />eruptions in the Newberry Volcano area and minor eruptions near Mt. Jefferson, at <br />Blue Lake Crater, in the Sand Mountain Field (Santiam Pass), near Mt. Washington, <br />and near Belknap Crater. During this time period, the most active volcano in the <br />Cascades has been Mount St. Helens with about 14 eruptions. <br /> <br />In addition, many other volcanoes in Oregon are deemed active or potentially active. <br />The Smithsonian Institution's Global Volcanism Project lists 20 active volcanoes in <br />Oregon. These volcanoes are listed below in Table 11 <br /> <br /> Table 11.1 <br /> Active VoLcanoes in Oregon <br /> <br /> Volcano Type Last Eruption <br /> Mt, Hood Stratovolcano 1866 <br /> 95O <br /> Mt. Jefferson Stratovolcano main volcano inacbve for <br /> >10,000 years <br /> Blue Lake Crater Crater 1490 BC <br /> Sand Mountain Field Cinder cones 1040 BC? <br /> 620 <br /> Mt Washington Shield volcano <br /> main volcano inactive <br /> Belknap Field Shield volcanoes 460? <br /> North S~ster Field Complex volcano 350 <br /> South Sister Complex volcano 50 BC? <br /> Mt. Bachelor Stratovolcano 5800 BC <br /> Davis Lake Volcamc field 2790 BC? <br /> 620 <br /> Newberry Volcano Shield volcano crater formabon 300,000 to <br /> 500,000 years ago <br /> Devis Garden Volcanic field unknown <br /> Squaw Rid,ge Lava Field Volcanic field unknown <br /> Four Craters Lava Field Volcanic field unknown <br /> Cinnamon Butte Cinder cones unknown <br /> 2290 BC <br /> Crater Lake Caldera Crater formation about <br /> 7,700 years ago <br /> Diamond Craters Volcanic field unknown <br /> Saddle Butte Volcanic field unknown <br /> Jordan Craters Volcamc field 1250 BC <br /> Jackies Butte Volcanic field unknown <br /> Public Review Draft: October 11, 2004 <br /> t1-1 <br /> <br /> <br />