Environmental hazard of capable faults: the case of the Pernicana Fault (Mt. Etna, Sicily)

When dealing with hazard, the concept of fault capability (the probability of significant surface displacement in the near future) is more useful than the generic and often misleading concept of fault activity. The example of the Pernicana fault, located in the north-eastern flank of the Mt. Etna vollcano is used here to illustrate the damage which can be expected in an urbanised area from a capable fault, in this case characterized by 'aseismic' creep along part of its length. Along this fault, buildings, roads and other essential lifelines are being affected by slow, left-lateral displacement. The Permicana fault is only one of a set of structures in the area whose movement, either connected to seismicity or not, is producing severe damage. First identified at the end of the last century, this source of hazard is, nevertheless, still poorly considered by planners and technicians. In Italy fault creep is quite rare outside the Etna region, but fault capability associated with strong earthquakes is relatively frequent, based on historical and palaeoseismological data, and is a feature that should be taken into account for hazard reduction programs.