SUMMER 2003GEOHAZARDS COURSE AT UWI, MONA - page 019

Prepared and compiled by Rafi Ahmad, Unit for Disaster Studies,
Department of Geography and Geology,
University of the West Indies, Mona, Kingston 7, Jamaica
The geological structure of the island is controlled by major northwest and west trending faults systems which appear to be seismically active (Fig.2). The present day landforms on the island are a result of a series of uplifts during the last 15-20 million years (Neogene). Some of these faults appear to have been active during recent times.
The above description of the physical environment suggests that the island of Jamaica represents a very fragile and sensitive geological environment. More than half of the islands total surface area of 11,264 km2 lies above an elevation of 300 m, with an approximately 30 percent under slopes above 350. These slopes are predisposed to mass movements. Human activities during the last 400 years have extensively interfaced with natural slopes in all of its watersheds. The hill slopes have been deforested and natural vegetation changed. The trend continues with new development encroaching potentially unstable slopes. Ruinate land is a common sight and accelerated mass movement related to landslides is a common phenomenon in all the upland watersheds.
The paucity of suitably located flat lands close to major urban centres and an ever-increasing demand for residential lands has led to widespread land reclamation. Some of the island's critical facilities such as airports and power-generating plants are located on reclaimed lands. The urban spread during the last two decades is mainly concentrated across the narrow coastal fringes and reclaimed lands and up the steep hillsides. This has further exposed the citizenry and infrastructure to hazards from general shaking, liquefaction - related ground failures, landslides, riverine flooding, storm surge and tsunamis. The combined effect of all these geohazards are likely to be manifold and lessons from the previous natural disasters suggest that they have a domino effect on human systems, populace and the physical environment.

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