Probabilistic Seismic-Hazard Assessment of the Canary Islands

Abstract

This article presents the first probabilistic seismic hazard assessment of the Canary Islands. The Canary Islands form a volcanic archipelago located on the passive margin of the African plate, 100 km off West Africa. Active volcanism has taken place on the islands in historical times, commonly together with the occurrence of volcanic-related seismic sequences, some of them felt as high as Imsk = X. In 1989 a notorious seismic sequence (mbLg 5.2) took place along a submarine fault located between the islands of Gran Canaria and Tenerife, clearly representing the occurrence of tectonic seismicity in the archipelago as well. In this article we review the geology and tectonics of the islands as well as recent paleoseismological findings on south Tenerife. We also revise, complete, and decluster the historical and instrumental seismic catalog of the islands. Seismic-hazard analysis is then performed following the standard Cornell (1968) method, defining three seismogenic sources and selecting an appropriate ground-motion attenuation relationship from Hawaiian data. Two hazard maps of the archipelago have been developed for return periods of 475 and 950 yr, as well as hazard curves for the capital cities. Calculated peak ground acceleration values at Santa Cruz de Tenerife and Las Palmas de Gran Canaria are 0.06 and 0.08g, and 0.05 and 0.07g, for the 475- and 950-yr return periods, respectively. Finally, we analyze the impact on hazard resulting from uncertainties associated with the seismogenic source model and the ground-motion attenuation relationship.