Publication Date:
2017-04-04
Description:
The technique of the wavefield polarization is applied to ambient vibrations recorded in the Mefite d’Ansanto
area, an important non-volcanic natural emission of low temperature CO2 enriched gases. Twentyfive
measurements were performed in the study area, eleven near the emission site and the other
fourteen in different sites within an area of 5 km. Polarization is assessed both in the frequency and time
domain through the individual-station horizontal-to-vertical spectral ratio and covariance-matrix analysis,
respectively. We find a significant tendency of ground motion in the gas emission area to be polarized
in the horizontal plane, with a N115 predominant trend. This polarization tends to disappear while moving
far from the site. According to previous papers in other study areas, such a directional effect is likely
caused by fault-induced fractures and tends to be orthogonal to the fracture strike. The predominant
NW–SE regional faulting does not fit the N115 polarization direction. To explain observations, we propose
an interpretation in terms of a NE–SW oriented, local transfer fault as inferred from the lineament
analysis. The intersection of the damage zone of this fault with the regional NW–SE normal fault system
could easily be the responsible for the gas emissions since it favors a locally increased crustal weakness.
Description:
‘‘Vigor-Geotermia’’ project http://
www.vigor-geotermia.it/
Description:
Published
Description:
116-123
Description:
5A. Energia e georisorse
Description:
JCR Journal
Description:
restricted
Keywords:
CO2 gas emission Directional resonance Fault damage zone Lineament analysis
;
04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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