Laboratory results indicating complex and potentially unstable frictional behavior of smectite clay

Demian M. Saffer, Kevin M. Frye, Chris Marone, Karen Mair

Research output: Contribution to journalArticle

96 Scopus citations

Abstract

A central problem in explaining the apparent weakness of the San Andreas and other plate boundary faults has been identifying candidate fault zone materials that are both weak and capable of hosting earthquake-like unstable rupture. Our results demonstrate that smectite clay can be both weak and velocity weakening at low normal stress (<30 MPa). Our data are consistent with previous work, which has focused on higher normal stress conditions (50 MPa and greater) and found only velocity strengthening. If natural fault zones contain significant smectite, one key implication of our results is that localized zones of high pore pressure, which reduce effective normal stress, could be important in controlling potential sites of earthquake nucleation. Our experiments indicate that friction of smectite is complex, and depends upon both sliding velocity and normal stress. This complexity highlights the need for detailed experiments that reflect in-situ conditions for fault gouges.

Original languageEnglish (US)
Pages (from-to)2297-2300
Number of pages4
JournalGeophysical Research Letters
Volume28
Issue number12
DOIs
StatePublished - Jun 15 2001

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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