LANDSLIDE TRIGGERING MECHANISMS IN JAMAICA:

Slope movement processes observed in Jamaica are both a natural geodynamic phenomenon through which hillslopes evolve, as well as a consequence of changing land use following unsustainable development activities during the last 400 years.
The most effective mechanism for triggering widespread landslide activity on the island is provided by the seasonal pattern of rainfall punctuated with intense storm events.
In general, landslides follow sustained rainfall which recharges the soils and deeply weathered bedrock present on steep slopes. This condition favours the development of excessive pore-water pressures which tend to reduce the shear resistance in slope materials leading to widespread slope failures.
For example, in one recorded instance, approximately 300mm of rainfall in 48 hours initiated shallow landslides that were quickly transformed into rapidly moving debris flows that caused extensive damage [Earle, 1991].

EARTHQUAKE events of Modified Mercalli Intensity VIII - X (greater than Richter Number 6.5) have been responsible for liquefaction and large scale landslides, whereas events below VIII have generally resulted in rock falls and debris slides [Ahmad, 1989c].
The earthquake of January 13, 1993 (Richter Number 5.4) triggered more than 40 landslides of different types in the parishes of Kingston and St. Andrew [Ahmad, 1993].