Volcano and Earthquake Hazards in the Crater Lake Region, Oregon
Potential Hazards From an Eruption Beneath Crater Lake
Although future eruptions could occur anywhere within Crater Lake caldera, all known postcaldera eruptions took place in the west half of the lake (fig. 3). Those eruptions produced andesite lava flows and tephra (Wizard Island, Merriam Cone, and the central platform), as well as a rhyodacite dome and minor ash fall. These events occurred between ~7,700 and ~5,000 years ago, most before the lake had risen to its present level. Any ash deposits above the shore of Crater Lake, which would have provided a record of associated explosive activity, evidently have been lost to erosion. Evaluation of hazards from eruptions beneath the lake must be based on historic eruptions elsewhere and knowledge of the general characteristics of volcanic eruptions in water.