THE GEOMORPHOLOGICAL CONTROLS ON SEISMICALLY TRIGGERED LANDSLIDES DURING THE 1908 STRAITS OF MESSINA EARTHQUAKE, SOUTHERN ITALY

Investigation of landslides which have been located from contemporary accounts of the Straits of Messina earthquake of 1908 reveals that a failure envelope for the slopes may be drawn on the basis of slope height-slope angle relationship for static and dynamic stresses. As would be expected there is a decrease in stability during the earthquake to a degree which is almost certainly linked to the generation of pore water pressures. However, a region of the failure envelope shows much greater decrease in stability; this section of the curve describes the stability of low slope height-high slope angle forms. The area for which this stability curve has been calculated is affected by a nearfield earthquake. It is suggested that these slopes are suffering from forced vibration from high-frequency accelerations. In support of such of a hypothesis of a geomorphological control is the observation that many of the landslides along this section of coastline occurred at topographic irregularities.