Scaling of fracture energies: The rationalization of different laboratory measurements

Abstract

The fracture energy GC is an important parameter involved in earthquake processes. Researchers have been trying to estimate GC from both geophysical field data and laboratory fracture experiments conducted on either intact rocks or frictional contacts (faults) simulated by saw-cut rocks. The GC measured from these two types of experiments can differ by several orders of magnitude, and the reason for this difference is still unknown. I show that if we divide GC into three parts, namely surface energy, frictional fracture energy, and the damage zone energy, we can explain this discrepancy through simple scaling relations. I also attempt to make the connection from the laboratory measured GC to the seismological estimates. Copyright 2006 by the American Geophysical Union.