Synthetic seismograms (P-SV and SH waves) have been calculated along six profiles in SantiagodeCuba basin, with a cutoff frequency of 5 Hz, by using a hybrid approach (modal summation for a regional 1D structure plus finite differences for a local 2D structure embedded in the first). They correspond to a scenario earthquake of MS=7 that may occur in Oriente fault zone, directly south of the city. As initial data for a seismicmicrozoning, the characterisation of earthquake effects has been made considering several relative (2D/1D) quantities (PGDR, PGVR, PGAR, DGAR, IAR—ratios of peak ground values of displacement, velocity and acceleration, and of design ground acceleration and Arias intensity-, etc.) and functions representative of the groundmotion characteristics in soil (2D) with respect to bedrock (1D). The functions are the response spectra ratio RSR(f), already routinely used in this kind of work, and the elastic energy input ratio EIR(f), defined, for the first time, in this paper. These data, sampled at 115 sites within all the profiles have been classified in two steps, using logical combinatory algorithms: connected components and compact sets. In the first step, from the original groundmotion parameters or functions extracted from the synthetic seismograms, nine sets have been classified and the partial results show the spatial distribution of the soil behaviour as a function of the component of motion. In the second step, the results of the classification of the nine sets have been used as input for a further classification that shows a spatial distribution of sites with a quasi-homogeneous integral groundmotion behaviour. By adding the available geological surface data, a microzoning scheme of SantiagodeCuba basin has been obtained.
Seismic microzoning from synthetic ground motion parameters: case study, Santiago de Cuba
VACCARI, FRANCO;PANZA, GIULIANO;
2005-01-01
Abstract
Synthetic seismograms (P-SV and SH waves) have been calculated along six profiles in SantiagodeCuba basin, with a cutoff frequency of 5 Hz, by using a hybrid approach (modal summation for a regional 1D structure plus finite differences for a local 2D structure embedded in the first). They correspond to a scenario earthquake of MS=7 that may occur in Oriente fault zone, directly south of the city. As initial data for a seismicmicrozoning, the characterisation of earthquake effects has been made considering several relative (2D/1D) quantities (PGDR, PGVR, PGAR, DGAR, IAR—ratios of peak ground values of displacement, velocity and acceleration, and of design ground acceleration and Arias intensity-, etc.) and functions representative of the groundmotion characteristics in soil (2D) with respect to bedrock (1D). The functions are the response spectra ratio RSR(f), already routinely used in this kind of work, and the elastic energy input ratio EIR(f), defined, for the first time, in this paper. These data, sampled at 115 sites within all the profiles have been classified in two steps, using logical combinatory algorithms: connected components and compact sets. In the first step, from the original groundmotion parameters or functions extracted from the synthetic seismograms, nine sets have been classified and the partial results show the spatial distribution of the soil behaviour as a function of the component of motion. In the second step, the results of the classification of the nine sets have been used as input for a further classification that shows a spatial distribution of sites with a quasi-homogeneous integral groundmotion behaviour. By adding the available geological surface data, a microzoning scheme of SantiagodeCuba basin has been obtained.Pubblicazioni consigliate
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