A seismicity revision and a probabilistic seismic hazard assessment using the Monte Carlo approach for the Canary Islands (Spain)

Abstract

This study consists of a seismicity revision and the assessment of the probabilistic seismic hazard of the Canary Islands. In order to analyze its seismotectonics and associated seismic hazard, we performed a full revision of the seismicity of this region of oceanic intraplate seismicity, whose earthquake rate is low and its links to local tectonics are poorly understood. In this catalog, we designed a criterion for assigning the epicenter of historical events and homogenized the different magnitude values defined over time for earthquakes from the instrumental period. This analysis of the seismicity of the region and the structural lineaments obtained by previous geophysical studies enabled us to define two possible seismic zonings, which were then used in the probabilistic seismic hazard assessment. Given the special characteristics of the seismicity of the Canary Islands, we chose a Monte Carlo approach for calculating the hazard. We used the two alternatives provided by EqHaz open-source code (Assatourians and Atkinson, Seismol Res Lett 84:516–524, 2013; Seismol Res Lett 90:1407–1419, 2019), namely uniform and smoothed seismicity. Given that no ground motion prediction equation (GMPE) for the area is available, we selected the most robust and recent applicable relations from similar tectonic environment and checked the fit of the existing accelerometric data for the Canary Islands. We mixed the aleatory and epistemic uncertainties for each area of the two zonings in the hazard calculation. With this approach, the values obtained may be considered in the context of an extreme-value distribution of motions at a specific site after converting the simulated earthquakes into earth motion with the selected GMPEs. The final outcome is hazard maps for different periods in terms of horizontal acceleration at bedrock level, which we compared with the results deduced from recent hazard studies in the area.