LANDSLIDE SUSCEPTIBILITY ZONES- DEEP LANDSLIDES:

The definition of landslide susceptibility zones requires dividing the spectrum of landslide densities into a manageable number of discrete classes. Our final five classes divide the density spectrum into roughly equal pieces, except for the highest class which must include densities as high as 71%. However, since there are very few pixels with densities of >10%, this highest susceptibility class does not occupy much area on the map.

The Landslide Susceptibility Class maps for deep landslides shows:

Low susceptibility to landsliding, in the entire Liguanea Plain, most of the Red Hills, granodiorite outcrop, and Long and Dallas Mountains.

Moderate-susceptibility class includes gently sloping areas in the Wagwater Belt, mainly near wide valley floors, or on low-relief ridge crests and uplands. Some steeper slopes on the flanks of Long and Dallas Mountains, and along the fault line scarp north of Red Hills, are in this class.

Moderate-high susceptibility is found on many valley slopes in the Wagwater Belt, on lithologic units EA, ESS, and ECV.

Susceptibility becomes high within 4 pixels (60 m) of fault traces in this same terrain. If slopes are very steep, or aspects southerly, these fault-related areas may fall into the very high susceptibility class. Interestingly, the largest area with very high susceptibility is in far eastern St. Andrew east of the Yallahs River. These very high densities are found in Cretaceous volcanics (CV) on steep slopes traversed by closely spaced faults. Similar very high densities occur along the fault-line scarp north of Red Hills, and on the flanks of Long and Dallas Mountains. However, the densities for the latter areas are based on very few landslide pixels, and thus the susceptibility class may be too high.