The development and present status of seismic research work in Jamaica, West Indies

Abstract

Jamaica is located near the northern boundary of the Caribbean Plate and is within a seismically active zone. Historic records of earthquakes date back to the sixteenth century during the early period of European settlement and colonization. During the last four centuries more than 4000 lives have been lost as a result of local seismic events and there are at least 55 documented cases in which there was an earthquake of intensity VI or greater on the Modified Mercalli Scale. The Seismic Research Unit of the University of the West Indies first began its operation in Jamaica in 1963 with the installation of three short period vertical-component seismometers. Since 1963 the number of stations has increased and there is now a network of five short-period vertical-component seismometers linked by radio telemetry to the base recording station at the Mona Campus of the University of the West Indies. Seismic events are recorded on 600-m reels of magnetic tape and the position of each event is located by first replaying and then transcribing the data on the tape for the five stations onto strip chart. P and S arrival times are then read into an IBM-PC and the magnitude and epicentre determined by using the ‘JCA-HYPO’ program, based on a four-layer model for Jamaica. In addition to the network of seismic stations there are six strong motion accelerographs, which are deployed in high-rise buildings in urban and rural Jamaica. Since their installation in the mid-1970s only one earthquake, in 1978, yielded a good strong motion record. In 1983 the Jamaica Bureau of Standards introduced a National Building Code for engineers in which it recommended that structures be designed according to the code of the Structural Engineers' Association of California.