U.S. Geological Survey
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The Mount Hood fault zone is a N-trending, ~55 km-long zone of active faulting along the western margin of the High Cascades graben at the crest of the Oregon Cascade Range. Recent geologic mapping, fault scarp analysis, and a hand-dug paleoseismic trench on the Gate Creek fault, the northernmost segment of the Mount Hood fault zone, indicate the most recent earthquake occurred between AD 1363 and AD 1495. These dates overlap with tree-ring dates between AD 1446 and AD 1447 from trees drowned when the nearby Bonneville landslide blocked the Columbia River and impounded a lake 75 meters deep. The impounded lake then partly breached the landslide dam, causing downstream flooding in the Portland basin prior to AD 1479–1482.
We have returned to in-person presentations!
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63063 Layton Avenue, Bend
5:30 pm social hour
7:00 pm presentation
COGS talk are free and open to the public -- all are welcome! Please join us for the social hour before the presentation.
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Central Oregon Geoscience Society
P.O. Box 2154, Bend, Oregon 97709