The course of the San Andreas fault between Point Arena and San Bernardino undulates back and forth across a segment of a small circle with a radius of 9°. The pole of the circle is in southeastern Idaho, about 40 km (25 mi) south of Pocatello. This fault, associated with the great earthquakes of 1857 and 1906, is too curved to be a transform fault separating the rigid plates of North America and the Pacific.

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