Please use this identifier to cite or link to this item:
http://hdl.handle.net/2122/359
Authors: | Italiano, F.* Martinelli, G.* Rizzo, A.* |
Title: | Geochemical evidence of seismogenic-induced anomalies in the dissolved gases of thermal waters: A case study of Umbria (Central Apennines, Italy) both during and after the 1997-1998 seismic swarm | Journal: | Geochemistry, Geophysics, Geosystems | Series/Report no.: | 11/5(2004) | Publisher: | American Geophysical Union | Issue Date: | 2-Nov-2004 | DOI: | 10.1029/2004GC000720 | URL: | http://www.agu.org/ | Keywords: | dissolved gases geochemistry seismic areas |
Subject Classification: | 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations 05. General::05.02. Data dissemination::05.02.01. Geochemical data 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data |
Abstract: | In this paper we present the first geochemical data set regarding long-term monitoring of dissolved gases in thermal waters from a seismic area. Three sites in Umbria (Central Apennines, Italy) were studied both for the chemical and for the helium isotopic composition of the dissolved gases. Data were collected during and after the seismic crisis that struck the region in 1997â 1998. The chemical composition of the dissolved gases revealed that a CO2-rich gas phase was always mixed with an atmospheric-derived component dominated by N2. A normal faulting marked the beginning of the seismic activity enhancing the release of CO2 on a regional scale. Variations in both the chemical and isotopic compositions of the dissolved gases were also observed as preseismic, synseismic, and postseismic phenomena related to the seismic shock of March 1998. Those geochemical modifications were interpreted as being the consequence of a drop in the CO2 degassing rate, in good agreement with the compressive focal mechanism of that seismic event. Furthermore, this interpretation was also consistent with the geologic and tectonic setting of the study area and induced us to postulate that changes in the local rock permeability, due to crustal deformations (i.e., coseismic deformation and postseismic release), were responsible for the geochemical modifications observed. On the basis of the foregoing, we have concluded that the geochemistry of dissolved gases in groundwaters represents a useful tool for the investigation of the relationships between circulating fluids and seismic activity. |
Appears in Collections: | Article published / in press |
Files in This Item:
File | Description | Size | Format | Existing users please Login |
---|---|---|---|---|
Italiano G3 2004.pdf | Main article | 329.75 kB | Adobe PDF | |
Redirect AGU.html | Redirect-AGU | 503 B | HTML | View/Open |
WEB OF SCIENCETM
Citations
23
checked on Feb 7, 2021
Page view(s) 50
174
checked on Apr 17, 2024
Download(s)
83
checked on Apr 17, 2024