Seismically induced ground effects of the 1805, 1930 and 1980 earthquakes in the Southern Apennines (Italy

Seismically induced environmental effects (in particular, surfacefaults, ground cracks, slope
failures, liquefaction, soil compaction, hydrological changes, tsunamis) are assumed to provide
fundamentalinformation on the earthquake size and its intensity field, crucial for a more
efficient seismic hazard assessment. Accordingly, this study is aimed at substantiating this
assumption by showing that the knowledge about ground effects acquired in recent
earthquakes, when combined with that illustrated in historical documents, allows to buildan
improved picture of historic seismic events, with respect to that usually provided by the solely
damage-based macroseismic scales. In this perspective, the environmental effects are
analysed and cataloguedof three of the most ruinous earthquakes in Southern Italy of the last
two centuries: the July 26,1805, Molise event (XI MCS, M 6.8), the July 23, 1930, Irpinia event
(X MCS, M 6.7), and the November 23, 1980 Campania-Basilicata event (X MSK, Ms 6.9). The
distribution of the earthquake environmental effects, in particular their distance from the
known or supposed causative fault, has been investigated to obtain a more detailed and
comprehensive picture of the macroseismic field, a key parameter in seismic hazard
assessment and seismic zonation.
KEY WORDS: historical seismicity, intensity, ground effects, earthquake