Historic Earthquakes
Near Lake Chelan, Washington
1872 12 15 05:40 UTC (local 12/14)
Magnitude 6.8
Largest Earthquake in Washington
This earthquake evidently had a large magnitude, because it was felt from British Columbia, Canada, to Oregon and from the Pacific Ocean to Montana. It occurred in a wilderness area, which in 1872 had only a few inhabitants - local Indian tribes, trappers, traders, and military men. Because there were few man-made structures in the epicentral area near lake Chelan, most of the information available is about ground effects, including huge landslides, massive fissures in the ground, and a 9-meter-high geyser.
Extensive landslides occurred in the slide-prone areas of the Columbia River. One massive slide, at Ribbon Cliff (between Entiat and Winesap), blocked the Columbia River for several hours. A field reconnaissance to the Ribbon Cliff landslide area in August 1976 showed remnants of a large landslide mass along the west edge of Lake Entiat (Columbia River Reservoir), below Ribbon Cliffs and about 3 kilometers north of Entiat. Although the most spectacular landslides occurred in the Chelan-Wenatchee area, landsliding was reported throughout the Cascades.
Most of the ground fissures occurred at the east end of Lake Chelan in the area of the Indian camp; in the Chelan Landing-Chelan Falls area; on a mountain about 19 kilimeters west of the Indian camp area; on the east side of the Columbia River (where three springs formed); and near the top of a ridge on a hogback on the east side of the Columbia River. These fissures formed in several localities of differing physiographic environments. Slope failure or settlements or slumping in water-saturated unconsolidated sediments may have produced the fissures in areas on steep slopes or near bodies of water. Sulfurous water was emitted from the large fissures that formed in the Indian camp area. At Chelan Falls, "a great hole opened in the earth" from which water spouted as much as 9 meters in the air. The geyser activity continued for several days, and, after diminishing, left permanent springs.
In the epicentral area, one log building on unconsolidated river deposits near the mouth of the Wenatchee River was damaged. The upper logs and roof of the cabin were displaced, and the kitchen was separated from the main building. People there were thrown to the floor; waves were observed in the ground; and loud detonations were heard. About 3 kilometers above the Ribbon Cliff slide area, the logs on another log cabin caved in.
Damaging intensities in Washington (MM intensity VI) extended on the west throughout the now densely populated Puget Sound basin and on the southeast to beyond the Hanford nuclear reactor site. The earthquake also was reported in Idaho, Montana, Oregon, and Canada. Many aftershocks were observed in the area over the next 2 years.
Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.
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