GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 2.1 297 is not well constrained. We can however state that it seems to be located either on a southern prolonging of the fault involved in the 2016 rupture or along an EW trending fault. This means that the most probable site of occurrence of a large earthquake will be one where an event of this kind could occur but it has not been observed during the last seven hundred years. This means that we should change our approach in seismic risk management, since those areas are probably at a higher risk: as it has been dramatically shown this year, no new large event occurred in l’Aquila and instead a nearby area, Laga Mountains, was stricken. Finally we must remember that deeper events and off-shore events were not considered but they can be extremely destructive, such as the 1743 one that stroke Salento, Southern Puglia, causing large destruction in Nardò. References Fracassi U., Valensise G.; 2007: Unveiling the sources of the catastrophic 1456 multiple earthquake: Hints to an unexplored tectonic mechanism in southern Italy . BSSA, 97, 725-748, DOI 10.1785/0120050250. Galli P., Giaccio B., Messina P., Peronace E.; 2016: Three magnitude 7 earthquakes on a single fault in central Italy in 1400 years, evidenced by new palaeoseismic results . Terra Nova, 28, 146-154, DOI 10.1111/ter.12202. Gasperini P., Bernardini F., Valensise G., Boschi E.; 1999: Defining seismogenic sources from historical earthquake felt reports . BSSA, 89 , 94-110. Locati M., Camassi R., Rovida A., Ercolani E., Bernardini F., Castelli V., Caracciolo C.H., Tertulliani A., Rossi A., Azzaro R., D’Amico S., Conte S., Rocchetti E.; 2016: DBMI15, the 2015 version of the Italian Macroseismic Database . Istituto Nazionale di Geofisica e Vulcanologia. DOI 10.6092 /INGV.IT -DBMI15. Rovida A., Locati M., Camassi R., Lolli B., Gasperini P. (eds); 2016: CPTI15, the 2015 version of the Parametric Catalogue of Italian Earthquakes . Istituto Nazionale di Geofisica e Vulcanologia. DOI 10.6092 /INGV.IT - CPTI15. Wells D. H., Coppersmith K. J.; 1994: New Empirical Relationships among Magnitude, Rupture Length, Rupture Width, Rupture Area, and Surface Displacement . BSSA, 84 , 4, 974-1002. Homogenization of magnitude estimates in terms of Mw of Italian earthquakes occurred before 1981 B. Lolli 1 , P. Gasperini 2 , A. Rebez 3 1 Dipartimento di Fisica e Astronomia, Universita` di Bologna, Bologna, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Bologna, Italy 3 Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste, Italy In the last two decades, several studies have addressed the revaluation and homogenization of the Italian instrumental seismic catalog but all of them referred to the time interval since 1981, that is the starting date of the Catalogo Strumentale dei Terremoti Italiani (CSTI). At the time of its compilation in 2003, CSTI was thought as a continuation of the catalog of the Progetto Finalizzato Geodinamica (PFG) but, over the time, the latter has been almost totally forgot and presently it is even difficult to get as it is not provided by any web-site. In this work, we integrated a genuine copy of PFG, with additional locations from the bulletins of the Istituto Nazionale di Geofisica (ING, now known as INGV) and of the International Seismological Center (ISC) and with local magnitudes from two couples of Wood-Anderson seismometers operating in Italy in the 1970�� ��� ������ ������� ���� � ������� �������� �� ����� ��������� �� ’ � s and 1980 � ������� ���� � ������� �������� �� ����� ��������� �� ’s derived from a careful scrutiny of paper bulletins of the Osservatorio Geofisico Sperimentale (OGS, now known as INOGS) and ING. We restricted our analysis to the time interval from 1960 to 1980 because, based on various evidences, we can argued that within such period most instrumental magnitudes reported by the PFG catalog are reasonably coherent with the Richter�� ����������� ���������� �������� �� ��� ��� ������� ��� ’� ����������� ���������� �������� �� ��� s definition. Magnitudes provided by the PFG catalog and other data-sources have been calibrated with respect to Mw by general orthogonal regressions. The dataset from 1960 to 1980 contains about 8800 earthquakes, for about 5500 of which we provide an Mw magnitude estimate and related uncertainty. The analysis of the frequency- magnitude distribution indicates completeness for about Mw≥4.0.