Hi Carol. This forecast is very close to the northern end of the Parkfield seismic gap. It appears to start about 25 to 30Km south of Parkfield and ends about 40 to 45Km south of Parkfield.

This puts it very close to Cholame where they think the epicenter of the 1857 quake was as there were a number of quakes in this area just before the 1857 quake. There are also those who say the epicenter of the quake was at Parkfield, which didn’t exist at this time. Which ever place in centered at it was still a good size shaker.

The earthquake was strongly felt from Los Angeles to San Francisco. The rupture on the surface of the earth can still be traced to this day, extending from near Parkfield, California, to near San Bernardino, California, over a distance of roughly 225 miles. Strong shaking from the earthquake was said to have lasted from 1 to 3 minutes.

In comparison to the other "great" earthquakes of historic times, the 1857 "Fort Tejon" earthquake was larger than the 1872 Owens Valley (estimated magnitude 7.8) quake, and was equally as large as, if not larger than, the 1906 "San Francisco" earthquake (estimated magnitude 7.9-8.0). Estimates for "Fort Tejon" are also in the vicinity of magnitude 8.0. The 1857 and 1906 events were both on the San Andreas Fault, although the 1906 earthquake ruptured the northern segment of the fault, from Hollister (San Benito Co.) northward, for 400 km (250 miles.

The average recurrence interval for this earthquake has been estimated at 140 years +/- 40 years. Since it is already 145 years since the last earthquake, the next one may not be too far in the future. Take Care…Don in creepy town