This photo shows how a fence built across the fault might have looked immediately after the 1906 earthquake. The fence has been reconstructed from century-old materials found on this Preserve. An original section of this fence is still standing on the downhill side of the trail toward Los Trancos Creek. During the 1906 quake, faulting may have moved the far (right hand) segment as much as 3 feet in a northwesterly direction. 

In 1906, about 400 miles of the San Andreas Fault slipped, from San Juan Bautista to Cape Mendocino. Starting off at the Golden Gate Bridge, the fault unzipped itself at over 5,000 miles per hour, taking 20 seconds to reach this point. However, the northern part of the fault slipped much more than the southern part of the fault. The section north of the Golden Gate Bridge shifted about 15 to 16 feet, the section between San Francisco and Portola Valley shifted 7 to 9 feet, and from this area southward it only shifted 2 to 3 feet. The 1906 earthquake may not have released all the energy stored in the southern part of the fault. Smaller quakes, similar to the Loma Prieta, may have released the energy. In any case, energy is continuously being stored underfoot and you should be prepared for the results of its release.