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 1997-1998. 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 CO 2 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.

Italiano, F., Martinelli, G., Rizzo, A. (2004). Geochemical evidences of seismogenic-induced anomalies in the dissolved gases of thermal waters: a study case of Umbria (Central Apennines, Italy) both during and after the 1997-98 seismic swarm. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS, 5(11), 1-11 [10.1029/2004GC000720].

Geochemical evidences of seismogenic-induced anomalies in the dissolved gases of thermal waters: a study case of Umbria (Central Apennines, Italy) both during and after the 1997-98 seismic swarm

Rizzo A
2004

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 1997-1998. 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 CO 2 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.
Articolo in rivista - Articolo scientifico
Dissolved gases; Geochemistry; Seismic areas;
English
2004
5
11
1
11
Q11001
reserved
Italiano, F., Martinelli, G., Rizzo, A. (2004). Geochemical evidences of seismogenic-induced anomalies in the dissolved gases of thermal waters: a study case of Umbria (Central Apennines, Italy) both during and after the 1997-98 seismic swarm. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS, 5(11), 1-11 [10.1029/2004GC000720].
File in questo prodotto:
File Dimensione Formato  
Italiano-2004-Geochem Geophys Geosys-VoR.pdf

Solo gestori archivio

Descrizione: Article
Tipologia di allegato: Publisher’s Version (Version of Record, VoR)
Licenza: Tutti i diritti riservati
Dimensione 329.75 kB
Formato Adobe PDF
329.75 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/428887
Citazioni
  • Scopus 31
  • ???jsp.display-item.citation.isi??? 29
Social impact