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| Titel |
The permeability and elastic moduli of tuff from Campi Flegrei, Italy: implications for ground deformation modelling |
| VerfasserIn |
M. J. Heap, P. Baud, P. G. Meredith, S. Vinciguerra, T. Reuschlé |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 5, no. 1 ; Nr. 5, no. 1 (2014-01-24), S.25-44 |
| Datensatznummer |
250115252
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| Publikation (Nr.) |
 copernicus.org/se-5-25-2014.pdf |
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| Zusammenfassung |
| The accuracy of ground deformation modelling at active volcanoes is a
principal requirement in volcanic hazard mitigation. However, the reliability
of such models relies on the accuracy of the rock physical property
(permeability and elastic moduli) input parameters. Unfortunately,
laboratory-derived values on representative rocks are usually rare. To this
end we have performed a systematic laboratory study on the influence of
pressure and temperature on the permeability and elastic moduli of samples
from the two most widespread lithified pyroclastic deposits at the Campi
Flegrei volcanic district, Italy. Our data show that the water permeability
of Neapolitan Yellow Tuff and a tuff from the Campanian Ignimbrite differ by
about 1.5 orders of magnitude. As pressure (depth) increases beyond the
critical point for inelastic pore collapse (at an effective pressure of
10–15 MPa, or a depth of about 750 m), permeability and porosity decrease
significantly, and ultrasonic wave velocities and dynamic elastic moduli
increase significantly. Increasing the thermal stressing temperature
increases the permeability and decreases the ultrasonic wave velocities and
dynamic elastic moduli of the Neapolitan Yellow Tuff; whereas the tuff from
the Campanian Ignimbrite remains unaffected. This difference is due to the
presence of thermally unstable zeolites within the Neapolitan Yellow Tuff.
For both rocks we also find, under the same pressure conditions, that the
dynamic (calculated from ultrasonic wave velocities) and static (calculated
from triaxial stress-strain data) elastic moduli differ significantly. The
choice of elastic moduli in ground deformation modelling is therefore an
important consideration. While we urge that these new laboratory data should
be considered in routine ground deformation modelling, we highlight the
challenges for ground deformation modelling based on the heterogeneous nature
(vertically and laterally) of the rocks that comprise the caldera at Campi
Flegrei. |
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