Spatial variability earthquakes

Characterization and spatial variability of earthquake ground motions Nonlinear finite element analysis Site response... 

The effect of this difference, called spatial variability of earthquake motion (SVEGM), on extended stmctures is addressed in this entry. Other sorurces of variability such as the result from relative surface fault motion for recording stations located on either side of a causative fault, soil liquefaction, and landslides (Zerva and Zervas 2002) are not considered herein. Finally, although SVEGM has been extensively studied for horizontal component and at free surface, some dense seismic arrays have been instmmented to record motion with respect to vertical component and/or at depth. 

In order to take into account of the spatial variability of earthquake-induced ground motions, let us consider an n-DoF structural system subjected to an N support motion. It follows that the stochastic forcing vector process has to be modeled as a multi-correlated zero-mean Gaussian random vector process ... 

In the framework of stochastic seismic analysis, the main distinct phenomena that give rise to the spatial variability of earthquake-induced groimd motions are (i) the incoherence ect associated to loss of coherency of seismic waves due to the differential superpositioning of waves arriving from an extended source, (ii) the wave-passage ect due to difference in the arrival times of waves at separate supports, (iii) the attenuation effect due to gradual decay of wave amplitudes with distance due to energy... 

The remaining two observations (v) and (vi) relate to the spatial and temporal variability of earthquake evolution within individual clusters. In the following sections, we investigate the hypothesis that this variability is consistent with pressure diffusion within faults that contain a spatially structured heterogeneous transmissivity field. Detailed results from these investigations at A u are presented in Nascimento et al (2003c). 

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