Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 7 3 2007 10.5194/nhess-7-405-2007 http://www.nat-hazards-earth-syst-sci.net/7/405/2007/ http://www.nat-hazards-earth-syst-sci.net/7/405/2007/nhess-7-405-2007.html http://www.nat-hazards-earth-syst-sci.net/7/405/2007/nhess-7-405-2007.pdf 405 416 2007-06-14 An automatic monitoring network installed in Tuscany (Italy) for studying possible geochemical precursory phenomena R. Cioni M. Guidi L. Pierotti A. Scozzari a.scozzari@igg.cnr.it CNR Institute of Geoscience and Earth Resources, Pisa, Italy Since late 2002, a continuous automatic monitoring network (CAMN) was designed, built and installed in Tuscany (Italy), in order to investigate and define the geochemical response of the aquifers to the local seismic activity. The purpose of the investigation was to identify eventual earthquake precursors. The CAMN is constituted by two groups of five measurement stations each. A first group has been installed in the Serchio and Magra graben (Garfagnana and Lunigiana Valleys, Northern Tuscany), while the second one, in the area of Mt. Amiata (Southern Tuscany), an extinct volcano. The measured parameters are: T, pH, Eh, EC, dissolved CO2 and CH4. The results of three years of continuous monitoring can be summarised as follows: i) the monitoring stations made it possible to detect even small variations of the measured parameters, with respect to equivalent commercial devices; ii) acquired data made it possible to identify the groundwater circulation patterns; iii) in most locations, the observed trend of the acquired parameters is consistent with the periodic manual sampling results, and confirms the mixture of different water types that the hydrogeochemical model has determined. The absence of seismic events with a sufficient energy precluded the possibility to locate anomalies, with the only exception of the Equi Terme site, where an increase in the dissolved CO2 content was observed twelve days before a M=3.7 earthquake occurred at a distance of 3 km north of the monitoring station. The CAMN resulted as being a suitable tool in order to investigate the anomalous variations of the physical, physico-chemical and chemical parameters of aquifer systems as earthquake precursors. Baldacci, F. and Raggi, G.: Lineamenti geologici e idrogeologici della regione dell'Appennino Ligure Toscano a nord dell'Arno. Contributo alle conoscenze delle risorse geotermiche del territorio italiano, C.N.R., PFE-SPEG, RF 13, 68–85, 1982. Baldacci, F., Cecchini, S., Lopane, G., and Raggi, G.: Le risorse idriche del bacino del fiume Serchio ed il loro contributo all'alimentazione dei bacini idrografici adiacenti, Mem. Soc. Geol. It., 49, 365–391, 1993. Bencini, A., Duchi, V., and Martini, M.: Geochemistry of thermal springs of Tuscany, (Italy), Chemical Geology, 19, 229–252, 1977. Bencini, A., Brondi, M., Dall'Aglio, M., Duchi, V., Quattrocchi, F., and Venni, G.: Ricerca di siti idonei all'istallazione di stazioni di monitoraggio di parametri idrogeochimici pertinenti ai terremoti, nell'area della Garfagnana, Atti GNGTS, 101–114, 1990. Biagi, P. F., Ermini, A., Kingsley, S. P., Khatkevich, Y. M., and Gordeev, E. I.: Possible Precursors in Groundwater Ions and Gases content in Kamchatka (Russia). Phys. Chem. Earth, A, 25, 295–305, 2000. Boschetti, T., Venturelli, G., Toscani, L., Barbieri, M., and Mucchibo, C.: The Bagni di Lucca thermal waters (Tuscany, Italy): an example of Ca-SO4 waters with high Na/Cl and low Ca/SO4 ratios, J. Hydrol., 307, 270–293, 2005. Calamai, A., Cataldi, R., Squarci, P., and Taffi, L.: Geology, Geophysics and Hydrogeology of the Monte Amiata Geothermal Field, Geothermics, Special Issue 1, 1–9, 1970. Calvi, E., Caprai, A., Leone, G., and Mussi, M.: Isotopic and chemical composition of some thermal groundwaters and associated gases in the Serchio river valley, Northern Tuscany, Italy, Atti Soc. Tosc. Sci. Nat. Mem., Serie A, 106, 45–53, 1999. Carapezza, M. L., Cioni, R., Guidi, M., Lelli, M., Pruiti, L., Ricci, T., and Scozzari, A.: The importance of automatic continuous geochemical monitoring in an open conduit volcano (Stromboli, Italy), EGS-EGU, Vienna, 2005. Carmignani, L., Decandia, F. A., Fantozzi, P. L., Lazzarotto, A., Liotta , D., and Meccheri, M.: Tertiary extensional tectonics in Tuscany (Northern Appennines, Italy), Tectonophysics, 238, 295–315, 1994. Celati, R., Grassi, S., and Calore, C.: Overflow thermal springs of Tuscany (Italy), J. Hydrol., 118, 191–207, 1990. Chiodini, G., Cioni, R., Di Paola, G., Dotsika, E., Fytikas, M., Guidi, M., Leonis, C., Lyberopoulou, V., Magro, G., Marini, L., Meletidis, S., Michelot, J. L., Poutoukis, D., Raco, B., Russo, M., and Virgili, G.: Geochemistry of Santorini fluids, Final Report, Contract EV5V-CT93 (DG12 SOLS), 1996. Cioni, R., Guidi, M., and Raco, B.: The Automatic Geochemical Monitoring of Volcanoes project, final Report on the research project supported by contract ENV4-CT96-0289 (DGXII-ESCY), project co-ordinator: Allard, P., 1999. Cioni, R. and Guidi, M.: European Mobile Early Warning System, final Report, Contract ENV4-CT98-0728 (DG12-ESCY), 2001. Jolivet, L., Faccenna, C., Goffé, B., Mattei, M., Rossetti, F., Brunet, C., Storti, F., Funiciello, R., Cadet, J. P., D'Agostino, N., and Parra, T.: Midcrustal shear zones in postorogenic extension: example from the northern Tyrrhenian Sea, J. Geophys. Res., 103, 12 123–12 160, 1998. De Stefani, C.: Le acque termali di Torrite in Garfagnana, Boll. Soc. Geol. It., XXIII, I, 117–148, 1904. Duchi, V., Minissale, A., Paolieri, M., Prati, F., and Valori, A.: Chemical relationship between discharging in the Siena-Radicofani graben by the geothermal field of the Mt. Amiata, Torre Alfina and Latera (central Italy), Geothermics, 21, 401–413, 1992. Eva C., Giglia G., Graziano F., and Merlanti, F.: Seismicity and its relation with surface structures in the North-Western Apennines, Boll. Geof. Teor. Appl., XX, 79, 263–277, 1978. Fancelli, R. and Nuti, S.: Studio sulle acque geotermiche e minerali della parte orientale della provincia di Siena, Boll. Soc. Geol. It., 94, 135–155, 1975. Fancelli, R. and Agostini, G.: Le acque di Bagni di Lucca nei loro rapporti con le altre manifestazioni idrotermali nella Toscana settentrionale, Atti delle giornate Bagni di Lucca Terme; Bagni di Lucca, 3–4 maggio 1980. Fanelli, M., Bellucci, L., and Nachira, F.: Manifestazioni idrotermali italiane. CNR – PFE, Geothermal Energy Subproject RF 13, Appendix, 1982. Francalanci, G. P.: Contributo per la conoscenza delle manifestazioni idrotermali della Toscana, Atti Soc. Toscana Sci. Nat., Serie A 65, 373–432, 1959. Frepoli, A. and Amato, A.: Contemporaneous extension and compression in the Northern Apennines from earthquake fault-plane solutions, Geophys. J. Int., 129, 368–388, 1997. Frepoli, A. and Amato, A.: Spatial variation in stress in peninsular Italy and Sicily from background seismicity, Tectonophysics, 317, 109–124, 2000. Garavaglia, M., Braitenberg, C., Zadro, M., and Quattrocchi, F.: Radon measurements in soil and water in the seismic Friuli area, Il Nuovo Cimento, 22C, 415–422, 1999. Hartmann, J. and Levy, J.: The influence of seismotectonics on the precursory changes in groundwater composition for the earthquake, Japan, Hydrol. J., 14, 1307–1318, 2006. Johansen, A., Saleur, H., and Sornette, D.: New evidence of earthquake precursory phenomena in the 17 January 1995 Kobe earthquake, Japan, The European Physical Journal B, 15, 551–555, 2000. Johansen, A., Sornette, D., Wakita, H., Tsunogai, U., Newman, W., and Saleur, H.: Discrete scaling in earthquake precursory phenomena: evidence in the Kobe earthquake, Japan, J. Phys. I France, 6, 1391–1402, 1996. King, C. Y.: Gas geochemistry applied to earthquake prediction: an overview, J. Geophys. Res., 91, B12, 12 269–12 281, 1986. King, C. Y.: Gas geochemical approaches to earthquake prediction, In: Radon Monitoring in Radioprotection, Environmental Radio-Activity and Earth Sciences, ICTP, Trieste, 244–277, 1989. Langelier, W. F. and Ludwig, H. F.: Graphical methods for indicating the mineral character of natural waters, J. Am. Water Works Ass., 34, 335–350, 1942. Marinelli, G.: Genèse des magmas du volcanisme Plio-Quaternaire des Apennines, Geol. Rundsch., 57, 127–141, 1967. Masini, R.: Studi geoidrologici sulle acque fredde e calde (Alpi Apuane e bacino del Serchio), Boll. Servizio Geologico d'Italia, 78, 709–788, 1956. Masini, R.: Le terme di Equi (Alpi Apuane) e l'origine delle sorgenti termominerali, Boll. Servizio Geologico d'Italia, 85, 95–125, 1964. Meletti, C. and Valensise, G.: Zonazione sismogenetica ZS9. Gruppo di lavoro per la redazione della mappa di pericolosità sismica, zonesismiche.mi.ingv.it/documenti/App2.pdf, 2004. Nucci, M., Marchetti, G., Guidi, M., Zanzari, A. R., Scozzari, A., and Galli, G.: Geochemical responses of the aquifers to the seismic events: the Micrat project, AVR05 Aquifer Vulnerability and Risk International Workshop, Piacenza, 2005. Peccerillo, A.: Multiple mantle metasomatism in central southern Italy: geochemical effects, timing and geodynamic implications, Geology, 27, 315–318, 1999. Pieri, C. and Burichetti, E.: L'acqua termale di Pieve Fosciana. Analisi, indagini e considerazioni chimico-fisiche, Atti Soc. tosc. Sci. Nat. Mem., 40, 1–20, 1930. Pulinets, S. A. and Dunajecka, M. A.: Specific variations of air temperature and relative humidity around the time of Michocan earthquake M8.1, 19 September 1985 as a possible indicator of interaction between tectonic plates, Tectonophysics, 431, 221–230, 2007. Quattrocchi, F. and Calcara, M.: Test-site for earthquake prediction experiments within the Colli Albani region, Phys. Chem. Earth, 23, 915–920, 1998. Quattrocchi, F., Guerra, M., Pizzino, L., and Lombardi, S.: Radon and helium as pathfinders of fault systems and groundwater evolution in different Italian Areas, Il Nuovo Cimento, 22 C, 309–316, 1999. Rosini, R., Di Luccio, F., and Barba, S.: Focal mechanism in the Apennines, Phys. Chem. Earth, 21, 273–278, 1997. Serri, G., Innocenti, F., and Manetti, P.: Geochemical and petrological evidence of the subduction of delaminated Adriatic continental lithosphere in the genesis of the Neogene-Quaternary magmatism in central Italy, Tectonophysics, 223, 117–147, 1993. Singh, R., Cervone, G., Singh, V., and Kafatos, M.: Generic precursors to coastal earthquakes: Inferences from Denali fault earthquake, Tectonophysics, 431, 231–240, 2007. Thomas, D.: Geochemical precursors to seismic activity, PAGEOPH, 126, 241–266, 1988. Toutain, J. P., Baubron, J. C.: Gas geochemistry and seismotectonics: a review, Tectonophysics, 304, 1–27, 1999. Trevisan, L., Dallan, L., Federici, P. R., Giglia, G., Nardi, R., and Raggi, G.: Foglio 96 Massa, Note illustrative della Carta geologica d'Italia, scala 1:100.000, Servizio geologico d'Italia, 1971. Ulomov, V. I. and Mavashev, B. Z.: Forerunners of the Taskent earthquake, Izvestia Akadamiyi Nauk Uzbeckistan SSR, 188–200, 1967. Wakita, H.: Water wells as possible indicators of tectonic strain, Science, 189, 553–555, 1975. Wyss, M. and Booth, D. C.: The IASPEI procedure for the evaluation of earthquake precursors, Geophys. J. Int., 131, 423–428, 1997. Zanzari, A. R., Martinelli, A., Cioni, R., Guidi, M., Raco, B., Scozzari, A., Quattrocchi, F., Galli, G., and Mancini, C.: Discrete and continuous monitoring of groundwater in the seismic area of the Umbria region (Italy), Proceeding of Water-Rock Interaction 2001, edited by: Cidu, R., Swets, J. A., and Zeitlinger, N. V., Lisse, ISBN 90 2651 824 2, 1, 119–122, 2001.