Abstract

Surface heat flow and stress orientations around the San Andreas Fault suggest anomalously low frictional strengths. Despite over 30 years of research, no clear consensus exists over the importance and causes of such weakness. This talk will present new geological observations from rocks sampled at 3.3km depth – the heart of the San Andreas Fault. The weakening mechanisms seen in these samples highlight the fundamental role played by fluid-rock interactions in upper crustal fault zones. Interestingly, there are very significant similarities between the fault rock processes seen here and those preserved along other deeply exhumed weak fault elsewhere in the world.

This is an abstract summary. For the full abstract, please e-mail sks38@cam.ac.uk