Seismic Hazard Map for Cuba and Adjacent Areas Using the Spatially Smoothed Seismicity Approach

Abstract

The seismic hazard assessment for Cuba and the surrounding regions has been performed according to the spatially smoothed seismicity approach. The major motivation for using this methodology is to avoid drawing seismic sources in a region where the seismogenic structures are not well known. We have defined two different seismicity models and three zonation models, based on the evidence of seismotectonic heterogeneity of the broader Cuban region, and two attenuation models for rock and three for soil. The resulting hazard estimates have been treated with a logic tree approach. The highest hazard was obtained around Santiago de Cuba with a PGA larger than 0.28 g on rock and 0.40 g on soil, for a 475-year return period. When the epistemic uncertainties of the different models considered are taken into account, these ground motion values exceed 0.40 g on rock and 0.60 g on soil. A comparison between these new hazard estimates and those computed according to the standard approach of the seismotectonic probabilism indicates the areas where the spatial distribution of the seismicity supports the seismogenic zonation and the areas where a disagreement exists.

Seismic Hazard for Cuba: A New Approach

“…The catalog magnitudes, completeness periods, and earthquake locations are all subjected to increasing uncertainty when going back in time (and up in magnitude), and likewise the zonation is subjective and the line fault activity only reflects mapped fault structures (blind faults are, for natural reasons, not included). In spite of all the inherent uncertainties, we believe that the obtained results represent a useful step on the ladder toward more reliable hazard estimates, not the least through application of more recent GMPEs. A comparison with already published results in terms of PGA for a 475-year return period (García, 2007;Garcia et al, 2008) shows that our results for PGA + SDe (SDe is the epistemic standard deviation or σ e ) are comparable with the García (2007) zonified cases for PGA + SDa (SDa is the aleatoric standard deviation) and with some of them presented by Garcia et al (2008) for nonzonified cases. In these works, there has never have been a unification of both kinds of cases in a single logic tree.…”

“…The first attempts to calculate seismic hazard directly in terms of PGA were done by García et al (2003), also including a logic-tree framework. After that, Garcia et al (2008) used a zoning-free method to develop more hazard estimates for Cuba. García (2007) updated the estimates done in 2003, but he did not include the zonation-free results in the logic tree.…”

Probabilistic seismic hazard assessment for Thailand

“…The intrinsic drawback of this method is that the seismic hazard assessment results can be significantly affected by the delineation of these zones, which could be heavily dependent on the subjective judgment of the hazard analyst. In order to move away from this traditional approach, the smoothed gridded seismicity approach (Frankel 1995) has been successfully adopted in many countries (Frankel 1995;Lapajne et al 1997Lapajne et al , 2003Garcia et al 2008). The possible drawback of this method is its strong dependence on quality of the earthquake catalogue (e.g.…”