| Abstract: | This paper examines the risk from fault offset to a building constructed over the surface trace of a fault. An expression relating the magnitude of surface offset to its return period is derived using classical seismic hazard analysis. The risk from fault offset is compared with that due to ground shaking by comparing offsets and MM intensities with equal likelihoods of occurrence. The comparison of risks is useful since it enables risk from fault movement to be related to levels of community acceptance as expressed in building codes for design against ground shaking effects. Relative risk is independent of fault activity rate, but does depend on regional constants, principally those describing the attenuation of MM intensities. For a site over an isolated fault in the Wellington, New Zealand region the risk of damage from fault rupture appears to be about equal to that from ground shaking for buildings with poor earthquake resistance (e.g. unreinforced masonry structures). But for structures designed to have some resistance to ground shaking, the risk due to fault rupture is considerably greater than that due to ground shaking. |
