Abstract

The Commonwealth of Puerto Rico, an unincorporated territory of the United States, and the smallest island of the Greater Antilles, is approximately 200 km by 60 km; it is also the island with the highest population densities within the Caribbean region.  Several historical earthquakes have caused extensive damage to Puerto Rico and have generated Tsunami. There is a great concern to many geophysicists who believe that the subduction zone (Puerto Rico Trench) may be due for a major event because it has not ruptured in over 200 years.  This research provides a description of the Peak Ground Acceleration (PGA) and instrumental Intensity (IMMI) distribution of significant moderate magnitude (5.0≤M≤6.4) earthquakes, the temporal-spatial patterns of the regional and local seismicity, within Puerto Rico Island (PRI) occurred during the last two decades, the lessons we have learned from them, and their association with the known mapped faults and the historical earthquakes (M≥7.0), as well as to the un-known faults and the earthquake epicentral clusters within the PRI and Caribbean region.  In addition, the tectonic frame and faults of the region and the Puerto Rico Strong Motion Program (PRSMP) seismic network instruments coverage and distribution is provided.  Finally, it was found the most recent Puerto Rico Seismic Hazard Map (2003), contained in the current building code, does not take into account the multiple partially studied active seismic faults that were found within the Island and that at least one of them could generate magnitude 7.5 earthquakes. Update the PRI Seismic Hazard Map considering the new identified active faults and the new findings of the seismic studies and the local site effects is plenty justified.