The 28 March 1783 earthquake (Catanzaro Graben, Southern Italy): the seismogenic structure within the seismic hazard evaluation
Osservatorio Sismologico, V. Osservatorio 4, 98121 Università degli Studi di Messina, Italy
Coauthors: Antonio Bottari(1), Antonio Teramo(1), Christian Sue(2). (1) Osservatorio Sismologico, V. Osservatorio 4, 98121 Università degli Studi di Messina, Italy. (2) Geological Institute, Neuchâtel University, CP2, 2007 Neuchâtel Switzerland.
Some of the results, taken from the modelling of the macroseismic intensity virtual distribution relative to the 28 March 1783 earthquake, are analysed, with the aim of removing any ambiguities in the characterization of the seismic source.
Is to be noticed, preliminarily, that the seismogenic zone of the Catanzaro Graben, contiguous to the seismogenic zone of the Mesima Graben, is located along the southern region of the Calabrian Arc, an area strongly struck by the seismic sequence of the 1783 earthquakes, which occurred on the 5-6-7 February and 1-28 March with X-XI MCS intensities (Jacques et al., 2001).
In particular, the seismic source of the 5-6-7 February and 1 March seismic events that struck the Mesima Graben, migrated, during the 28 March seism, towards the Catanzaro Graben. Such a migration indicates that the source area of the above-mentioned earthquakes moved from the Mesima Graben seismogenic zone (a tectonic structure dominated by NNE-SSW seismogenic normal faults) towards the Catanzaro Graben one (a tectonic depression mainly bordered by WNW-ESE trending faults). The design of the felt area of the 28 March earthquake through the intensity virtual distribution shows an elliptical area, characterised by a NE-SW trending minimum attenuation axis (Teramo et al., in press, Termini et al., in press), very different from that designed by Baratta (1901), where the mesoseismic field is stretched along a WNW-ESE direction.
In this regard, it is to be noticed, moreover, both that some variations of the attenuation directions had already been described in the study area by Leone (1783) and recent investigations on the ruins of '600 monasteries in the Catanzaro area indicate also the presence of fractures coherent with a normal fault system with NE-SW trend. Further elements related to structural analyses of recent faults, paleoseismology, archaeoseismology, geomorphology and Carbonium 14 dating will be taken into consideration in a research study in progress, aimed at the determination of significant differences in the seismic hazard evaluation to be related to a different characterization of the seismic source.
Date received: September 23, 2004
Copyright © 2004 by the author(s). The author(s) of this work and the organizers of the conference have granted their consent to include this abstract in Topology Atlas. Document # caon-64.