Ribbon Cliff landslide Washington, and the earthquake of 14 December 1872

Estimates of the epicentral location and maximum intensity of the earthquake of 14 December 1872, the largest and oldest historic earthquake documented in the Pacific Northwest, are controversial largely because the estimates are based on ground effects. The Ribbon Cliff landslide is one of the more critical ground effects used to argue that the epicenter was in the vicinity of Lake Chelan in central Washington. Sketchy historical accounts link the Ribbon Cliff landslide to the 1872 earthquake, but a subsequent study disputed the historical accounts and, on the basis of dendrochronology, concluded that the landslide occurred more than 100 yr prior to the earthquake. However, Quaternary stratigraphic relations and the results of multiple dating techniques reported here indicate that the main Ribbon Cliff landslide probably occurred within a 14-yr period that includes the time of the 1872 earthquake. Although our study supports the historical accounts that link the landslide to the December 1872 earthquake, it does not prove that seismic shaking triggered the landslide.