Assessing geohazards in Kingston, Jamaica

Supervisor: Mattew J Hornbach (Southern Methodist University, Dallas, Texas)
The island of Jamaica extends ∼230 km along the Gonâve–Caribbean Plate boundary and straddles faults that accommodate Gonâve–Caribbean Plate motion (Mann, et al. 1995). This leaves the island and the city of Kingston in particular vulnerable to large strike-slip and thrust earthquakes. Kingston has experienced several developments in recent times which also add to the hazard risk. Both the physical and economic effects of an earthquake near Kingston could be catastrophic. Here we analyse sediments physical properties along Port Royal and Palisadoes sand spit to assess the strength of sediments in this region, and the probability of failure. We compare our results to historical studies and develop models to assess the probability of failure at Port Royal and the surrounding area in the future. As an initial, first-order approach for analysis of slope stability, we use a pseudostatic inertial method. This approach provides a strong-case end-member assessment for sediment strength and failure probability at Port Royal. The liquefaction Factor of Safety analysis at Port Royal suggests relatively minor ground shaking can cause potentially significant liquefaction at this site. Probability analysis indicates a return period of 18-29 years for the area for Mw 5 events. This would suggest that the Kingston/Port Royal area is due for an earthquake in the Mg 5 range in the near future. This study indicates such moderate earthquake events will cause liquefaction and associated damage along the Palisadoes on human time scales (with an occurrence rate of perhaps 2-3 times per century). Our hope is that this study will be used in Jamaica for future hazard mitigation and city planning.