Historic Earthquakes

Kern County, California
1952 07 21 11:52:14 UTC
Magnitude 7.3

Kern County, California This earthquake was the largest in the conterminous United States since the San Francisco shock of 1906. It claimed 12 lives and caused property damage estimated at $60 million. MM intensity XI was assigned to a small area on the Southern Pacific Railroad southeast of Bealville. There, the earthquake cracked reinforced-concrete tunnels having walls 46 centimeters thick; it shortened the distance between portals of two tunnels about 2.5 meters and bent the rails into S-shaped curves. At Owens Lake (about 160 kilometers from the epicenter), salt beds shifted, and brine lines were bent into S-shapes.

Many surface ruptures were observed along the lower slopes of Bear Mountain, in the White Wolf fault zone. The somewhat flat, poorly consolidated alluvium in the valley was erratically cracked and recontoured. The cracking along Bear Mountain indicated that the mountain itself moved upward and to the north. Southwest of Arvin, on the San Joaquin Valley floor, ground cracks traversed and spilt the concrete foundation on one house, causing partial collapse. The ground slumped; cotton rows were offset more than 30 centimeters; and pavement on one highway was crumpled for more than 300 meters. East of Caliente, one large crack, about 1.5 meter at its widest point and more than 60 centimeters deep, was observed. Fill areas in the mountainous regions along U.S. Highway 466 (now State Highway 58) settled from a few centimeters to more that 30 centimeters in places, and a large part of the highway was cracked and wrinkled. Northeast of that highway, the ground was displaced vertically about 60 centimeters and horizontally about 45 centimeters.

Maximum MM intensities in nearby cities did not exceed VIII. At Tehachapi, Bakersfield, and Arvin, old and poorly built masonry and adobe buildings were cracked, and some collapsed.

Property damage was heavy in Tehachapi, where both brick and adobe buildings were hit hard, and 9 people were killed. Three people were killed in other towns. Although damage was severe, the total extent of damage to property did not exceed that in Long Beach in 1933. Only a few wood-frame structures were damaged seriously in this earthquake, compared to the 1933 shock in which many such structures were thrown off foundations.

The generally moderate damage in Bakersfield was confined mainly to isolated parapet failure. Cracks formed in many brick buildings, and older school buildings were damaged somewhat. In contrast, however, the Kern General Hospital was damaged heavily. Multistory steel and concrete structures sustained minor damage, which commonly was confined to the first story. Similar kinds of damage also occurred at Arvin, which lies southeast of Bakersfield and west of Tehachapi.

Reports of long-period wave effects from the earthquake were widespread. Water splashed from swimming pools as far distant as the Los Angeles area, where damage to tall buildings was nonstructural but extensive. Water also splashed in pressure tanks on tops of buildings in San Francisco. At least one building was damaged in San Diego, and in Las Vegas, Nevada, a building under construction required realignment of the structural steel.

The main shock was felt over most of California and in parts of western Arizona and western Nevada. It was observed at such distant points as Stirling City, California, Phoenix, Arizona, and Gerlach, Nevada. The California Institute of Technology at Pasadena recorded 188 aftershocks of magnitude 4.0 and higher through September 26, 1952; six aftershocks on July 21 were of magnitude 5.0 and higher.

Railroad tracks near Bealvile, California, bent and twisted by the July 21, 1952, earthquake.
Railroad tracks near Bealvile, California, bent and twisted by the July 21, 1952, earthquake. (Photo from the National Geophysical Data Center.)


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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