THE MEAN TRANSMISSION PROPERTIES OF A FAULT WITH IMPERFECT FACIAL CONTACT

A model of a fault where the two faces do not exactly conform is chara cterized by a distribution of approximately circular contacts; elsewhe re, the faces are stress-free. This contrasts with most earlier models , which have assumed the contact geometry to be equivalent to a plane distribution of approximately circular cracks. The contact regions in the present model are taken to be sparsely distributed, and averaged i nterface conditions are derived that are accurate to second order. At lowest order they agree with established formulae for the normal stiff ness of non-conforming surfaces. These averaged, or mean, conditions a re expected to hold at wavelengths long compared with the radii and sp acing distance of the contact points. Unsurprisingly, they are equival ent to the continuity conditions for a thin elastic layer whose proper ties are given here in terms of the parameters of the contact surface.