On August 1, 1975, an earthquake measuring M 5.8 occurred along the western foothills of the Sierra Nevada, near Oroville. The quake was centered about 4.5 miles south of town, near the small community of Palermo, and was felt over a large area of northern California and western Nevada.

Damage in the epicentral area included toppled chimneys, broken windows, cracked walls, and downed lighting fixtures. Property damage was estimated at $2.5 million. The quake occurred along the little known Cleveland Hill fault, a small northern segment of the prominent Foothills Fault System.

The tremor caused nearly 2.5 miles of discontinuous surface fault ruptures which stopped just short of Oroville Dam. Maximum offsets were on the order of 2.5 inches, showing predominately vertical displacements, west side down. It was the largest earthquake ever recorded in the relatively quiet Sierra foothills.

Numerous aftershocks were recorded in the months that followed and minor seismicity still occurs from time to time.

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