Incorporation of crustal deformation to seismic hazard analysis

abstract The incorporation of the crustal deformation to the input parameters of the traditional probabilistic seismic hazard analysis is discussed on the basis of a relationship between the rate of crustal deformation and the seismicity parameters. The formulation is in terms of the seismic moment, which is defined as a function of the crustal deformation at the earthquake source, and a three-dimensional representation of seismogenic sources. The relationship between tectonic and seismicity parameters is presented in a graphical form, and its implications are discussed on the hazard of a seismic dislocation at a site on an earthquake fault. This hazard is directly related to the seismic slip part of crustal deformation. The introduction of the crustal deformation to the seismic hazard evaluation reduces the uncertainty associated with the long-term seismic behavior and elucidates the notion of the limiting size of an earthquake. Nevertheless, considerable uncertainty remains pertaining to the long-term stability of the seismic parameters. This uncertainty should be considered in the development of seismic criteria. The use of regional values of crustal deformation and present seismicity data is discussed for the San Andreas Fault in southern California and the Zagros Active Belt in southern Iran. In these determinations, it is necessary to differentiate between seismic slip and creep. This differentiation is particularly difficult in cases like the Zagros where seismic deformation has no direct surface manifestations.