Coefficient of the linear relationship between shear stress (Τ) and normal stress (σ n) on a fault or joint that is slipping Τ = S o + μ f σ n. See Lockner and Beeler (2002, p. 506), and section 5 in Ben-Zion (2003)
Peter Bormann, Keiiti Aki, William H. K. Lee, and Johannes Schweitzer (Compilers and Amenders), Glossary of Terms Interest to Earthquake and Engineering Seismologists (Version 1), Publication records from external use of GFZ scientific infrastructure, Germany 2011. http://gfzpublic.gfz-potsdam.de/pubman/item/escido c:56137:3/component/escidoc:56143/Glossary_rev1.pd f, (ND/ Erthq - Amer) {980}