Seismic Hazard Assessment based on a Random Field Model

Abstract eng:
A random field model is proposed to estimate the seismic hazard associated with linearly extending seismic sources like faults. An earthquake having at least a magnitude of m is assumed to occur whenever the total strain energy accumulated over the potential rupture plane exceeds the level corresponding to this magnitude. The spatial and temporal correlation characteristics of the resulting energy random field are taken into consideration explicitly. The seismic hazard prediction model is based on the asymptotic results of the level crossing theory of homogeneous random functions. Significant analytical simplicity is achieved by using a separable correlation model for the space and time components of the random field and by introducing the scale of fluctuation as a measure of correlation. A realistic approach for seismic hazard prediction should be based on models where the spatial and temporal components are treated simultaneously within the context of random field theory. The proposed model follows this approach and is expected to give better results than the classical seismic hazard analysis models because it describes the physical problem more realistically. The model introduces a substantial improvement over the simple Poisson model for earthquake sequences, since the exceedance (excursion) rates computed herein are adjusted for the degree of correlation in the space and time domains; in this respect, they differ from the exceedance rates of the simpler models, which ignore these dependencies completely. Consideration of spatial correlation by use of random field concepts is also an improvement over the renewal type models that take into consideration only the temporal dependence of earthquakes. Earthquakes that have recorded since 1907 along the most active segment of the North Anatolian fault are compiled to form an up to date seismic activity data base. This data base is then used to show the implementation of the proposed random field model for the assessment of seismic hazard.

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