GNGTS 2016 - Atti del 35° Convegno Nazionale

16 GNGTS 2016 S essione A matrice at Castelsantangelo sul Nera; and three minor springs near Forca di Presta along the Vettore fault (FP01, FP02 and FP03 sampling points). For most of these springs we will compare pre- earthquake and post-earthquake chemical and isotope geochemistry features. Analyses for collected water samples include in situ characterization of parameters as pH, electrical conductivity and temperature, major ions concentrations through ionic chromatography and trace elements evaluation through inductively coupled plasma- mass spectrometry (ICP- MS). Some samples will be analyzed from the Reno University lab to obtain data for stable isotopes ratio (sulfur, oxygen and hydrogen). Pre-earthquake data was obtained from the Reno University for the sampling points in the Rieti basin. For the Uccelletto spring in Valnerina, these data will be obtained through the analysis of water samples from the stock of drinking water bottles, thanks to the collaboration of Nerea S.p.A. Bottled water remains very stable regarding physico-chemical parameters, and permit to observe data before the earthquake (see for instance, the case of the Kobe earthquake; Tsunogai and Wakita, 1995). We have no pre-earthquake data for the two minor springs in Forca di Presta, and we analyze these springs to observe the post-earthquake effect through time on local near-fault aquifers with small hydrogeological basin. First results for the Rieti basins samples shows a decreasing trend, especially for the Peschiera spring, which fed the Roma aqueduct. We observe the reduction of electrical conductivity after the earthquake, and the decrease of some transition metals (Fe, Ni, Cr, Cu) from the beginning of September. This trend must be obviously confirmed based on the results of ongoing analyses. Acknowledgements. We are grateful to Dr P. Mariani, Nerea S.p.A., for the kind availability of water samples from the Uccelletto Spring. References Bosi, C., Galadini, F., Messina, P.,1993: Neotectonic significance of bedrock fault scarps: case studies from the Lazio- Abruzzi Apennines (Central Italy) . Z. Geomorph., Suppl.- Bd. 94, pp. 187–206. Fig. 3 – Sampling localities for hydrochemical analyses in the Vettore Fault vicinity and in the Rieti basin.