Holocene records of Puerto Rico trench earthquakes and tsunamis

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Coastlines from the Caribbean northward to the U.S. and Canadian Atlantic seaboard are susceptible to marine inundation by hurricanes and tsunamis. Potential sources of tsunami inundation include local (Puerto Rico trench) and far-field earthquakes. The historical record identifies far-field events, but no notable tsunamis originating from the Puerto Rico trench. It remains unclear whether outer rise or thrust ruptures, and their subsequent tsunamis, pose a greater risk to the western Atlantic. An outer rise rupture is not expected to generate any land-level change at Anegada, British Virgin Islands and is not considered to produce a large earthquake or tsunami. On the contrary, models indicate that a thrust earthquake scenario will generate 50 cm of coseismic subsidence and a subsequent tsunami that would inundate coastal areas stretching from the islands of the Caribbean to eastern Canada. To address this knowledge gap, Dr. Jessica Pilarczyk (Simon Fraser University) and Dr. Davin Wallace (University of Southern Mississippi) will apply an innovative combination of field, laboratory, statistical, and modelling techniques to a pre-Columbian sand sheet previously identified as possibly originating from a Puerto Rico trench tsunami. These methods will be applied to test the source of past ruptures along the Puerto Rico trench and answer questions about the possible magnitude of earthquakes and intensity of tsunami waves that can be expected in the future. An enhanced understanding of future earthquakes and tsunamis will allow coastal communities in eastern Canada to prepare for large-scale tsunami inundation by informing evacuation strategies and policy and planning decisions through scientific evidence-based public education, and identifying and preserving key natural coastal ecosystems (e.g., barrier islands and salt marshes) that serve as important barriers to tsunami inundation.