Nuovo catalogo nazionale dei processi di liquefazione avvenuti in occasione dei terremoti storici in Italia

Abstract

Electricity Board (ENEL) asked ISMES to carry on the geological and seismological research based on methodologies and data gained in 1991 (see Galli & Ferreli, 1993). An ad hoc historical seismic research has been carried out in order to compile a new catalogue including both cases and indications of liquefaction, connected with seismic events in Italy. The new Catalogue (see Table 1), numbers 307 cases of liquefaction occurring in concomitance with 63 earthquakes; for each case earthquake epicentral parameters (Intensity and Magnitude) and geographical coordinates of the involved site are given. The great number of cases (doubled compared with previous studies), together with parameters listed in Table 1, highlight significant correlations for the definition of liquefaction occurrence limits. It has been possible to correlate percent of cases versus epicentral distance (see Fig. 1); epicentral distance versus epicentral intensity (see Fig. 2); and percent of cases versus quake intensity (both epicentral and felt) (see Fig. 3). In Figure 4 site location is shown together with the limits of liquefaction-geologically prone zones (solid line), together with areas where VII MCS quakes were felt or areas involved in VIII (or greater) MCS degree events. Although not all information sources and data collected have been critically analysed, obtained results may be considered as a further step torwards the understanding of liquefaction phenomena. Moreover, the catalogue represents a basic National Catalogue on actual or supposed liquefaction cases following historical earthquakes. Because, in the same site, more than one event may be recorded as a "seismite due to liquefaction phenomena", the catalogue can also be the basis for in situ palaeoseimic investigations aimed at improving knowledge on historic arid prehistoric seismicity.