The earthquake fence at Olema shows the sudden transform motion along the San Andreas caused by the 1906 earthquake. 110 years on, has there been ANY additional displacement?


1 Answer 1


If your question is only about the location of said fence I can not answer it. If, however, you are interested in the greater area around that location or the San Andreas fault in General, the short answer is, yes, there has been additional displacement and the movement is ongoing.

This displacement is related to what one can call the earthquake cycle of surface deformation. Usually people differentiate between co-seismic (directly caused by an earthquake, the Olema fence is a beautiful example for this), post-seismic (caused by secondary earthquake effects, keywords are poroelastic and viscoelastic effects) and inter-seismic (which is the tectonically driven creep of a fault in between earthquakes).

Take a look at this article by Lisowski and others to see surface displacements along the SAF. Fig. 7 shows the area of interest and , though a bit hard to see, there is significant relative motion in between areas east and west of the fault. The number that they give for average relative plate motion is 35 mm/yr (which would be roughly 4m/13ft in 110 yrs).

To return to the fence, I can only assume that it has spread further apart in the last 110 years, but not having been there I can not be certain. It is possible, that the surface manifestation of the fault has turned to another spot. I do think it is unlikely that not at least part of the deformation can be seen at the fence's location. According to this book the co-seismic offset of the fence was 4.7 m, might be interesting to know what it is today.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.