Probabilistic Seismic Hazard Assessment at the Eastern Caribbean Islands

Abstract

A probabilistic seismic hazard analysis has been performed to compute probabilistic seismic hazard maps for the eastern Caribbean region (10°N-19°N, 59°W-64°W), which includes in the north the Leeward Islands (from Anguilla to Dominica) and in the south the Windward Islands (from Martinique to Grenada), Barbados, Trinidad, and Tobago. The analysis has been conducted using a standard logic-tree approach that allowed systematically taking into account the model-based (i.e., epistemic) uncertainty and its influence on the computed ground motion parameters. Hazard computations have been performed using a grid of sites with a space resolution of 0.025 degrees covering the territory of the considered islands. Two different computation methodologies have been adopted: the standard Cornell-McGuire approach (Cornell, 1968; McGuire, 1976) based on the definition of appropriate seismogenic zones (SZ), and the zone-free approach developed by Woo (1996), which overcomes the ambiguities related with the definition of seismic sources. The interplay and complexities between shallow crustal, intraplate, and interface subduction seismicity of the Caribbean region have been thoroughly investigated. By merging all available databases, a comprehensive and updated earthquake catalog for the region has been compiled. Also, a thorough investigation has been undertaken to identify the most suitable ground motion prediction equations to be used in the analyses. Uniform hazard spectra have been calculated for the horizontal component of ground motion (rock and level site conditions), 4 return periods (RP) (95-, 475-, 975-, and 2475-yr), and 22 spectral accelerations (SA) with structural periods ranging from 0 to 3 s. SAs at 0.2 and 1.0 s for 2475-yr RP have been calculated to allow the definition of seismic hazard in the region of study according to the International Building Code (IBC, International Code Council [ICC], 2009).

Comprehensive Probabilistic Seismic Hazard Analysis of the Andaman-Nicobar Regions

“…Similar methods were adopted by Iyengar and Ghosh (2004) and Raghu Kanth and Iyengar (2006) for the seismic hazard analysis of Delhi and Mumbai, respectively. In a very recent work, Bozzoni et al (2011) used the same criterion to assign maximum magnitude to a regional source zone. The usual trend is to use M max estimated for the source zone and assign it to all linear sources in that zone.…”

Probabilistic Seismic Hazard Assessment for Bridgetown-Barbados, Employing Subduction Interface Characteristic Earthquakes

“…The level of hazard prescribed by this research is substantially larger than previous works (i.e., Bozzoni et al [3] suggest 0.22 g for 475 years RP), this increment is attributed to two reasons: (1) Former works did not consider the possibility of megathrust earthquakes beneath Barbados, in fact the maximum magnitudes considered in previous works used for this zone yields 7.0-7.5 based solely on 500 year of earthquake history, much lower than the maximum magnitudes employed in this work: a M 8.0 within the exponential G-R relationship and the characteristic earthquakes within the magnitude range of M 8.3 to 9.0 based on slip rates; (2) only the classical method of Cornell-McGuire was taken into account in the computation of the disaggregation process for this work; the authors did not introduce in the logic tree formulation the free-zone method proposed by Woo [46] and used by Bozzoni et al [3] as well, it has been observed that the free zone methods yield lower hazards results than the classical Cornell method in areas of sparse seismicity in terms of short period components of ground motion [47,48].…”

“…The authors employed the earthquake catalogue and the Gutenberg Richter relationships (Table 1) developed by Bozzoni et al [3]. Fig.…”

“…The upper-crustal seismicity is concentrated within the upper 35 km of the Caribbean continental plate in the Lesser Antilles Arc [5], with epicenters plotting from the islands of Grenada to Anguilla within a nearly continuous belt of 100 km width along both, the axis of the principal active volcanoes and the inland and Table 1 Main features of the SZs (seismogenic sources) and Gutenberg-Richter Parameters (log N = a -bM) for the Eastern Caribbean [3]. It is noted that the depth set for the seismogenic zones SZ2 and SZ3 are variable in order to model the inclined slab beneath Barbados.…”

“…1) in terms of PGA (peak ground acceleration) and response spectra for 5% of critical damping in conjunction with a disaggregation scheme to obtain the magnitude-distance pair that contributes most to the hazard. Recent studies have computed the seismic hazard for the whole Eastern Caribbean including the Island of Barbados [3].…”