Hi Martin. You designate the area of Parkfield. I assume you're referring to the area of the two quakes south of Parkfield. That would be close to the suspected location of the epicenter of the Fort Tejon earthquake. As the name suggests, one idea was to locate it near the area of strongest reported shaking -- Fort Tejon. However, because there is evidence that foreshocks to the 1857 earthquake may have occurred in the Parkfield area, it is located on the map near the northwestern end of the surface rupture, just southeast of Parkfield, near Cholame.

The 2 most recent quakes (2.5Md on Tue. 02/13/2001 and the 2.0Md on Sat. 02/17/2001are almost at the epicenters of two 6.0M+ quakes one of which was a 6.5ML on 03/10/1922 and a 6.0ML on 06/08/1934. There were other quakes above the magnitude of 5.0Ml. One of those was the 5.5ML on 06/28/1966.

The surface rupture caused by the quake of 1857 was extensive. The San Andreas fault broke the surface continuously for at least 350 km (220 miles), possibly as much as 400 km (250 miles), with an average slip of 4.5 meters (15 feet), and a maximum displacement of about 9 meters (30 feet) (possibly greater) in the Carrizo Plain area. Kerry Sieh (1978) noted that the Elkhorn Thrust, a low-angle thrust fault near the San Andreas, may have slipped simultaneously in the 1857 quake -- an observation that a team of researchers (1996) have recently used to support the idea that future movements along the San Andreas fault zone might produce simultaneous rupture on thrust faults in and near the Los Angeles area, causing a terrible "double earthquake". See map at below link. Take Care…Don in creepy town

• Fort Tejon Quake