Coseismic geochemical variations in some gas emissions of Umbria region (Central Italy)

Coseismic geochemical variations have been detected in some gaseous vents a nd natural springs during the last seismic crisis occurred in Umbria region (Central Apennines), that started on September 26(th), 1997 with several m oderate earthquakes (up to Ml 5.8). The results of chemical analyses perfor med on both gas and water samples taken at a weekly rate, combined with ana lyses on continuous gas flow rate nearby San Faustino site, suggest that th e variations can be interpreted as possible consequence of the crustal perm eability changes induced by earthquake shaking. (C) 2000 Elsevier Science L td. All rights reserved.