ASSESSING GEOHAZARDS NEAR KINGSTON JAMAICA: NEW RESULTS FROM CHIRP SEISMIC IMAGING

Kingston, Jamaica, the capital of the Caribbean island nation of Jamaica, is prone to infrequent but devastating earthquakes and tsunamis, yet the locations of the faults responsible for generating these geohazards are poorly known. The city rests precariously at the western terminus of the Enriquillo-Plantain Garden Fault (EPGF)—the same fault that ruptured during the 12 January 2010 Haiti earthquake, destroying Port-au-Prince and killing about 250,000 people. Like Haiti, Jamaica has experienced a significant earthquake every few hundred years; however, the exact frequency and location of large earthquakes across Jamaica remain unclear. It has now been more than 100 years since Jamaica was struck by a large (>Mw 6.5) earthquake. Recent GPS studies suggest the EPGF is capable of generating a Mw 7.2–7.3 earthquake in Jamaica—an event with more energy than the 2010 Haiti earthquake. The goal of our study, funded by Geoscientists without Borders, is to (1) determine the location of faults in Kingston Harbour, (2) assess whether these faults are active, (3) determine whether harbor faults triggered local tsunami reported during the 1692 and 1907 Earthquakes, and (4) from this, constrain the risk of future geohazards across the region. Here, we focus our analysis on recent results from our January 2011 chirp seismic imaging survey of Kingston Harbour. These data reveal a complex fault system extending across the harbor and evidence for multiple slide and liquefaction events. Using sea-level curves as a means of constraining age, we suggest these faults are active. Our study indicates East Kingston, Highway A4, The Norman Manley Airport, and the town of Port Royal are all prone to significant damage during the next earthquake, including liquefaction, slope failure, and tsunamigenesis. By working with Jamaican universities and the Jamaican government, our study is revising and improving emergency preparedness across Kingston and Jamaica. Future sediment coring across the site will allow us to constrain even further the frequency of geohazards across this region.