Intermediate-depth seismicity of the lesser Antilles subduction slab, close to the Paria peninsula, Venezuela

Abstract

From a macroseismic investigation of earthquakes ranging between 45 and 150 km in depth and magnitudes Mw ≥ 5.0 since year 2000, related to the South American-Atlantic (SAA) subduction in the region of the southeastern Caribbean STEP, we have determined that the cities of Ciudad Guayana and Ciudad Bolívar, sitting at the northernmost edge of competent rock outcrops of the Precambrian craton of Guyana, show seismic intensities which do not comply with a normal attenuation pattern of decreasing intensities with increasing distance. This necessarily leads to the revision of the current Venezuelan seismic-resistant code (COVENIN 1756-1:2019), since the seismic hazard estimations for this southern region of Venezuela appear to be clearly underestimated.