GNGTS 2018 - 37° Convegno Nazionale

20 GNGTS 2018 S essione 1.1 Pozzo. In addition to the identification of a tectonic discontinuity, whose surface expression is the fracture zone offsetting the thermal bath of the site. Unfortunately, the investigation has not allowed imaging a clear fault plane at depth, but rather it highlighted a broad anomalous zone interpretable as a fault zone. This is ascribable to the shallow depth of geophysical investigation, to the lithology of outcropping rocks and to the circulation of fluids in the subsoil. The geochemical surveys suggest that the fault affecting the archaeological site could be still active and that the local hydrothermal system could record changes in the heat/gas flux coming from the magmatic system of Mt. Etna. Geoarchaeological evidence suggests the occurrence of an earthquake that produced a displacement of man-made structures and destructive effects on the ancient Roman remains, possibly in the middle-end of the third-century AD. Time constraints are inferred through the dating of the different buildings phases and on archaeological findings. This event was conceivably a local earthquake with a severe impact on archaeological structures. Unfortunately, the extension of the fracture zone at the surface does not provide reliable information on earthquake magnitude. The lack of well-documented historical accounts of seismic activity does not help with the recognition of coseismic deformation elsewhere. Consequently, this event could be either associated to the volcano-tectonic earthquake of 251 AD preceding the 252 AD eruption (see Guidoboni et al. , 2014), or alternatively to a local pure tectonic earthquake not mentioned in the Italian seismic catalogue. References Alparone S., Bonaccorso A., Bonforte A., and Currenti G,; 2013: Long-term stress–strain analysis of volcano flank instability: the eastern sector of Etna from 1980 to 2012 . J. Geophys. Res. Sol. Earth. 118 , 5098–5108. Azzaro R., Branca S., Gwinner K., and Coltelli M.; 2012: The volcano-tectonic map of Etna volcano 1:100.000 scale: morphometric analysis from high resolution DEM integrated with geologic active faulting and seismotectonic data . Ital. J. Geosci. 131 ,153-170. Azzaro R.; 2004: Seismicity and active tectonics in the Etna region: constraints for a seismotectonic model . In: Bonaccorso A, Calvari S, Coltelli M, Del Negro C, Falsaperla S (eds) Mt. Etna: volcano laboratory, vol 143. American Geophysical Union, Geophysical Monograph, Washington, pp. 205–220. Bonforte A., Guglielmino F., Coltelli M., Ferretti A., and Puglisi G.; 2011: Structural assessment of Mount Etna volcano from permanent scatterers analysis . Geochem. Geophys. Geosyst. 12 , Q0200. Branca S., Coltelli M., and Groppelli G.; 2011a: Geological evolution of a complex basaltic stratovolcano: Mount Etna , Italy . Ital. J. Geosci. 130 (3), 306–317. Branca S., Coltelli M., Groppelli G., and Lentini F.; 2011b: Geological map of Etna volcano, 1:50,000 scale . Ital. J. Geosci. 130 (3), 265–291. De Guidi G., Scudero S., and Gresta S.; 2012: New insights into the local crust structure of Mt. Etna volcano from seismological and morphotectonic data . J. Volcanol. Geotherm. Res. 223 , 83–92. Ferrara V.; 2010: Le acque termominerali di S. Venera al Pozzo Studi e indagini idrogeologiche. Mem. Rend. Ac. Sci. Lett. Zelant. Dafn., Serie V, vol IX. Giammanco S., and Bonfanti P.; 2009: Cluster analysis of soil CO 2 data from Mt. Etna (Italy) reveals volcanic influences on temporal and spatial patterns of degassing . Bull. Volcanol. 71 , 201-218. Guidoboni E., Ciuccarelli C., Mariotti D., Comastri A., Bianchi M.G.; 2014: L’Etna nella storia. Catalogo delle eruzioni dall’antichità fino al XVII secolo . INGV, Rome. Monaco C., and Tortorici L.; 2007: Active faulting and related tsunami in eastern Sicily and south-western Calabria . B.G.T.A. 48 (2), 163–184 Parkinson K.J.; 1981: An improved method for measuring soil respiration in the field . J. App. Ecol. 18 , 221-228. Tonani F., and Miele G.; 1991: Methods for measuring flow of carbon dioxide through soils in the volcanic setting . Istituto di Analisi Globale e Applicazioni C.N.R., Firenze, Italy.