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Prehistoric rock avalanches in the Olympic Mountains, Washington

January 1, 1992

Rock avalanches blocked streams in the Olympic Mountains southwest of Puget Sound during the past few thousand years. Limiting radiocarbon ages indicated that three or four of six avalanches occurred from 1000 to 1300 years ago or shortly thereafter. Most of the dates were from the outer preserved rings of trees drowned behind avalanche dams. These three or four avalanches may be coeval not only with one another but also with abrupt tectonic deformation in western Washington. No rock avalanches in the Olympic Mountains are known to have resulted from storms or earthquakes during the past century. The avalanches strengthen the case that a large prehistoric earthquake occurred in the Puget Sound region.

Publication Year 1992
Title Prehistoric rock avalanches in the Olympic Mountains, Washington
Authors R. L. Schuster, R.L. Logan, P. T. Pringle
Publication Type Article
Publication Subtype Journal Article
Series Title Science
Index ID 70016878
Record Source USGS Publications Warehouse