What about the onshore Gorda Plate in northern California? An earthquake of M 6.75 on November 23, 1873, on the thinly settled Oregon-California border may have been a slab earthquake. After this earthquake, cracks in the ground appeared on the trail between Crescent City and Gasquet in the Smith River Valley, and all the chimneys were knocked down. The highest intensity recorded was VIII, in a limited area in the northwestern corner of California, but intensities of V were felt over a broad area from Red Bluff in the south to McMinnville, Oregon, in the northern Willamette Valley. Newspaper accounts did not report any aftershocks.