Kingston Multi-hazard Assessment

Note: These guidelines are presented in draft form, pending review, update and approval by appropriate Government of Jamaica Agencies and other interested parties in Jamaica. These draft guidelines were excerpted from Chapter 4 of the KMA seismic hazard assessment.

Guidelines

There are a number of limitations to the maps produced by the KMA Seismic Hazard Assessment. Recognizing this, the following guidelines are provided for the proper use and interpretation of the study results.

Building codes are the primary means of mitigating the effects of strong earthquake shaking on buildings. The effects of local surface geology on expected shaking is accounted for by the use of seismic coefficients in the lateral force formula which corresponds to the soil profile types defined in various building codes and recommendations (e.g. section 4.3 of this study and the Uniform Building Code (ICBO, 1997); NEHRP Recommendations (1997)).

The maps produced by the KMA Seismic Hazard Assessment contribute to the success of the building code process and the establishment of minimum safety standards and acceptable levels of risk in Kingston. By acceptable level of risk, we mean a reasonable protection of public safety to reduce the risk for ground failure during an earthquake to a level that does not cause the collapse of buildings for human occupancy, but not to a level of no ground failure at all. Note this definition of acceptable level of risk is based on a life safety criterion for buildings, and may need to be defined differently for infrastructure and port facilities.

The maps produced by the KMA Seismic Hazard Assessment delineate seismic hazard zones, either actual fault zones (such as the Plantain Garden Fault) or areas susceptible to ground failure (such as the Palisadoes). These maps were developed using a combination of historic records, field investigations, and computer based modeling and mapping technology. These maps may not, however, identify all areas that have a potential for liquefaction, ground failure, strong ground shaking or other geologic hazards. Neither the maps nor the information on how the maps were prepared should be used as a substitute for site-specific investigations.

The maps should be used to guide development in seismic hazard zones, to promote effective implementation of evaluation and mitigation measures throughout the Kingston metropolitan area, to ensure that appropriate soil and geotechnical investigations are conducted, and that appropriate mitigation measures are incorporated into the development process. Mitigation measures are those consistent with established practice to reduce seismic risk to acceptable levels.

The object of detailed field investigations is to obtain sufficient information so that engineers and geologists can evaluate the nature and severity of the risk and develop a set of recommendations for mitigation actions. Detailed investigations commonly involve the collection of subsurface information through trenches, borings on or adjacent to the site. The subsurface exploration should extend to depths sufficient to expose geologic or subsurface water conditions that could affect slope stability or liquefaction potential.