Historical Earthquakes in Idaho

  1. Nov 10, 1884. Paris, Franklin County, Idaho
    The earthquake damaged houses considerably in Paris, about 100 km southeast of Pocatello, near the Idaho-Utah-Wyoming border. It knocked down chimneys and shook stock from shelves in Richmond, Utah, about 125 km north of Salt Lake City. In an area north of Ogden, Utah, the tremor shook a Utah and Great Northern Railroad train. Also reportedly felt at Salt Lake City, Utah, and Franklin, Idaho.
     
  2. Nov 11, 1905. Near Shoshone, Lincoln County, Idaho
    Cracks formed in the walls of the courthouse and schools in Shoshone, and plaster fell from ceilings in almost all the buildings. Felt from Salt Lake City, Utah to Baker, Oregon.
     
  3. Oct 14, 1913. North-central Idaho
    A tremor broke windows and dishes in the area of Idaho and Adams counties.
     
  4. May 13, 1916. Boise, Idaho
    The earthquake wrecked several brick chimneys at Boise and sent residents rushing into the street. The shock was described as "violent" at Emmett, 40 km north of Boise, and at Weiser, 96 km west of Boise. Reclamation ditches in the area were damaged. Pressure in a new gas well increased noticeably immediately after the shock. Also felt in western Montana and eastern Oregon.
     
  5. Nov 25, 1924. Near Wardboro, Franklin County, Idaho
    A slight earthquake in Franklin County on this date broke windows at Wardboro, cracked ceilings at Montpelier, and displaced furniture at Geneva and Montpelier.
     
  6. Near Sheep Mountain, southwest Idaho
    This earthquake apparently was most severe in the area of Fontez Creek, near Sheep Mountain, Idaho, where buildings were shaken so severely that occupants thought the structures were falling apart. A new cabin set on concrete piers was displaced on its foundation. Along Seafoam Creek, rocks and boulders were thrown down the hillside.

    Cracks about 30.5 m long formed in the ground in the Duffield Canyon trail along Fontez Creek. Cracks 2.5 to 7.5 cm wide extended for several meters in a continuous break near Seafoam. A section of the Rapid River Canyon wall (near Lime Creek) fell into the river. Also felt in Montana, Oregon, and Washington. Seventeen shocks were reported felt, the first of which was the strongest.
     
  7. Feb 14, 1945. Idaho City, Boise County, Idaho
    This tremor broke dishes at Idaho City and cracked plaster at Weiser, northwest of Boise in Washington County. Also felt in Montana, Oregon, and Washington.
     
  8. Sept 25, 1947. Boise, Ada County, Idaho
    Several large cracks formed in a well-constructed brick building at Boise, but damage generally was slight.
     
  9. Dec 19, 1957. Northern Idaho
    Timbers fell and mine walls collapsed at the Galena Silver mine near Wallace, Shoshone County.
     
  10. Aug 7, 1960. Near Soda Springs, Caribou County, Idaho
    Southeast of Pocatello and about 14 km east of Soda Springs, cracks formed in plaster and a concrete foundation at a ranch.
     
  11. Jan 27, 1963. Clayton, Custer County, Idaho
    Plaster and windows cracked at Clayton, northeast of Boise. Large boulders rolled down a hill at Livingston Camp, about 22 km south of Clayton. Several aftershocks were felt in the area.
     
  12. Sep 11, 1963. Central Idaho
    Plaster fell in buildings at Redfish Lake, south of Stanley in Custer County; a window pane was broken at a fire station in Challis National Forest.
     
  13. April 26, 1969. Ketchum, Blaine County, Idaho
    Cracks formed in concrete floors of structures in Warm Springs and Ketchum. Plaster was cracked at Livingston Mill, 20 km south of Clayton.
     
  14. Mar 28, 1975. Eastern Idaho
    In the Ridgedale area of the sparsely populated Pocatello Valley, this earthquake shifted several ranch houses on their foundations and toppled many chimneys. At Malad City, 20 km northeast of the epicenter, about 40 percent of the chimneys on old buildings were damaged. Total property damage was estimated at $1 million.

    Geologists observed one zone of ground fractures - about 0.6 km long and 5 cm wide - in the south-central section of the valley.
     
  15. Nov 27, 1977. Cascade, Valley County, Idaho
    Property damage was reported only at Cascade, a few kilometers east of the epicenter, near Cascade Dam. The tremor cracked foundations and sheetrock walls, separated ceiling beams, and left muddy water in wells and springs. Also felt in Oregon.
     
  16. Oct 24, 1978. Southeast Idaho
    Cracks formed in plaster and a concrete foundation at Thatcher in Franklin County. This earthquake was felt in Bannock and Franklin Counties of southeast Idaho, and at Plymouth, Utah, south of Pocatello, Idaho.
     
  17. Oct 14, 1982. Near Soda Springs, Caribou County, Idaho
    In the Soda Springs area, about 45 km southeast of Pocatello, bricks fell from chimneys and cracks formed in the foundation of a house and interior drywalls. Also felt in Utah and Wyoming.
     
  18. Oct 28, 1983. Borah Peak, Custer County, Idaho
    The Borah Peak earthquake is the largest ever recorded in Idaho - both in terms of magnitude and in amount of property damage. It caused two deaths in Challis, about 200 km northeast of Boise, and an estimated $12.5 million in damage in the Challis-Mackay area. A maximum MM intensity IX was assigned to this earthquake on the basis of surface faulting. Vibrational damage to structures was assigned intensities in the VI to VII range.

    Spectacular surface faulting was associated with this earthquake - a 34 km long northwest trending zone of fresh scarps and ground breakage on the southwest slope of the Lost River Range. The most extensive breakage occurred along the 8 km zone between West Spring and Cedar Creek. Here, the ground surface was shattered into randomly tilted blocks several meters in width. The ground breakage was as wide as 100 km and commonly had four to eight en echelon scarps as high as 1-2 m. The throw on the faulting ranged from <50 cm on the southern-most section to 2.7 m south of rock creek at the western base of Borah peak.

    Other geologic effects included rockfalls and landslides on the steep slopes of the Lost River Range, water fountains and sand boils near the geologic features of Chilly Buttes and the Mackay Reservoir, an increase or decrease in flow of water in springs, and fluctuations in water levels. A temporary lake was formed by the rising water table south of Dickey.

    The most severe property damage occurred in the towns of Challis and Mackay, where 11 commercial buildings and 39 private houses sustained major damage and 200 houses sustained minor to moderate damage.

    At Mackay, about 80 km southeast of Challis, most of the commercial structures on Main Street were damaged to some extent; building inspectors condemned eight of them. Damaged buildings were mainly of masonry construction, including brick, concrete block, or stone. Visible damage consisted of severe cracking or partial collapse of exterior walls, cracking of interior walls, and separation of ceilings and walls at connecting corners. About 90 percent of the residential chimneys were cracked, twisted, or collapsed.

    At Challis, less damage to buildings and chimneys was sustained, but two structures were damaged extensively: the Challis High School and a vacant concrete-block building (100 years old) on Main Street. Many aftershocks occurred through 1983. Also felt in parts of Montana, Nevada, Oregon, Utah, Washington, Wyoming, and in the Provinces of Alberta, British Columbia, and Saskatchewan, Canada.
Idaho Historical Earthquakes


Borah Peak 1983 isoseismal map