Landslide Susceptibility Zones for Shallow Landslides:

The spectrum of landslide densities was divided into six subjective classes based on the frequency of various landslide densities.
The four highest susceptibility classes (very high, high, moderate to high, moderate) span roughly an equal range of landslide densities.
Low susceptibility and non-susceptibility classes cover a much smaller range of densities, but contain many more pixels than the four high classes (e.g., the Liguanea Plain).
The Landslide Susceptibility Map shows the string effect of lithologic group. The three highest susceptibility classes (very high, high, and moderate-high) are almost exclusively restricted to lithologic groups EA and ESS. These two lithologies contained 68% of shallow landslides more than 90 m from roads, but cover only 21% of the study area. Their landslide densities are roughly 3.5 times higher than that of any other units. Within these lithologies, the highest susceptibilities are for pixels sloping 20-35 0 on the shoulders of ridges where slopes are strongly convex-upward, on slopes that do not face south or west.
IT MUST BE EMPHASIZED THAT THESE PIXELS REPRESENT SITES WHERE SHALLOW LANDSLIDES MAY INITIATE, AFTER WHICH THE DEBRIS WILL TRAVEL AN UNKNOWN DISTANCE DOWNSLOPE.
The "runout distance" of debris slide material depends greatly on whether the debris liquefies after initial failure. Ellen and Fleming (1987) concluded that the mobility of debris slide material is controlled by the ratio of water content at the time of failure to the liquid limit.
Materials most susceptible to debris liquefaction are low-density colluvium containing 8-25% clay, which collapses upon shearing (contractive behaviour).
Denser, clayey colluvium exhibits dilative behaviour upon shearing, thus failed slabs can absorb water, remain intact, and often come to rest not far downslope from the site of slide initiation.
THEREFORE, ADDITIONAL HAZARDS DUE TO DEBRIS FLOWS EXIST DIRECTLY DOWNSLOPE OF THE HIGH-SUSCEPTIBILITY AREAS SHOWN ON THE HAZARD MAP.
This has been observed during the debris flows triggered by October-November 1998 rainfall in KMA.
Several small areas of high susceptibility occur on Cretaceous volcanics (CV) both in eastern St. Andrew, and on the north-facing escarpment north of Red Hills.
In all other lithologies the highest susceptibility attained, even on north facing convex slopes, is moderate-high.
Most of the limestone areas (EL, ELC) have low susceptibility to shallow sliding, regardless of slope angle, aspect, or curvature. One explanation for this low susceptibility is that those lithologies yield little colluvium upon weathering, or that colluvium is permeable enough not to fail in debris slides.