Deep structure of a fault discontinuity

Relocated aftershocks at a fault discontinuity that ruptured in the 1992 La nders earthquake show that there is no simple connection between the Homest ead Valley and Emerson faults at depth. Rather, faulting within the discont inuity is as complex as observed at the surface. Both aftershocks and mains hock slip on the far side of the discontinuity, that is on the Emerson faul t, were confined primarily to depths above 10 km, whereas slip and aftersho ck activity on the near side of the discontinuity extended to 17 km. Simila r behavior was also observed at a fault discontinuity in the 1979 Coyote La ke earthquake and may be attributable to the greater effectiveness of dynam ic stress in inducing fault rupture at shallow depths.