Shear wave velocities and primary influencing factors of Campi Flegrei–Neapolitan deposits

Nunziata, C.; Mele, Rita; Natale, M.

doi:10.1016/s0013-7952(99)00044-7

Cited by 16 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Water content has a marked effect because when water replaces air it provides bridges between particles that greatly increase the conductivity of the soil. Assuming the thermal properties of soil constituents (K s = 2.9 W m −1 °C −1 , K w = 0.6 W m −1 °C −1 e K a = 0.025 W m −1 °C −1 ) reported by de Vries [1963], varying the porosity n from 0.20 to 0.50, a suitable range for the studied soils (e.g., at Solfatara, n was measured to be 0.46 [ Nunziata et al , 1999]), and considering that in temperate climates commonly x w > 0.15, we obtain thermal conductivities K c ranging from 0.4 to 2.1 W m −1 °C −1 which practically overlap the range of the values obtained in the Figure 10 (from 0.5 to 2.3 W m −1 °C −1 ) for the 30 campaigns.…”

Section: Resultsmentioning

confidence: 99%

Carbon dioxide diffuse degassing and estimation of heat release from volcanic and hydrothermal systems

et al. 2005

View full text Add to dashboard Cite

[1] We present a reliable methodology to estimate the energy associated with the subaerial diffuse degassing of volcanic-hydrothermal fluids. The fumaroles of 15 diffuse degassing structures (DDSs) located in eight volcanic systems in the world were sampled and analyzed. Furthermore, each area was measured for soil temperature gradients and for soil CO 2 fluxes. The results show that each hydrothermal or volcanic system is characterized by a typical source fluid which feeds both the fumaroles and diffuse degassing through the soil. Experimental data and the results of physical numerical modeling of the process demonstrate that the heat released by condensation of steam at depth is almost totally transferred by conduction in the uppermost part of the soil. A linear relationship is observed between the log of the steam/gas ratio measured in the fumaroles and the log of the ratio between soil thermal gradient and soil-gas flux. The main parameter controlling this relation is the thermal conductivity of the soil (K c ). For each area, we computed the values of K c which range from 0.4 to 2.3 W m À1°CÀ1 . Using the CO 2 soil fluxes as a tracer of the deep fluids, we estimated that the total heat released by steam condensation in the systems considered varies from 1 to 100 MW.

show abstract

Section: Resultsmentioning

confidence: 99%

Carbon dioxide diffuse degassing and estimation of heat release from volcanic and hydrothermal systems

et al. 2005

View full text Add to dashboard Cite

show abstract

“…The last observation fits quite well with the results of H/V analysis that shows higher resonance frequency values in the northeastern part of the crater, approaching the internal crater slopes, when compared to the central area. Moreover, the detected shear wave velocities for the shallower layers are typical of loose and unconsolidated pyroclastic deposits [ Nunziata et al , 1999].…”

Section: Discussionmentioning

confidence: 99%

Subsurface structure of the Solfatara volcano (Campi Flegrei caldera, Italy) as deduced from joint seismic‐noise array, volcanological and morphostructural analysis

Petrosino¹,

Damiano²,

Cusano³

et al. 2012

Geochem Geophys Geosyst

View full text Add to dashboard Cite

The joint application of different seismological techniques for seismic noise analysis, and the results of a volcanological and morphostructural survey, have allowed us to obtain a detailed and well constrained image of the shallow crustal structure of the Solfatara volcano (Campi Flegrei caldera, Italy). Horizontal‐to‐vertical spectral ratios, inversion of surface wave dispersion curves and polarization analysis provided resonance frequencies and peak amplitudes, shear wave velocity profiles and polarization pattern of coherent ambient noise. These results, combined in a unique framework, indicate that the volcanic edifice is characterized by lateral and vertical discontinuities and heterogeneities in terms of shear wave velocity, lithological contrasts and structural setting. The interpretation of the seismological results, with the volcanological and morphostructural constraints, supports the hypothesis that the volcano has been characterized by a complex and intense activity, with the alternation of constructive and destructive phases, during which magmatic and phreatomagmatic explosions built a complex tuff‐cone, later reworked by atmospheric agents and altered by hydrothermal activity. The differences in the velocity structure between the central and eastern parts of the crater have been interpreted as resulting from a possible eastward migration of the eruptive vent along the deformational features affecting the area, and to the presence of viscous lava and lithified tuff bodies within the feeding conduits, which are buried under a covering of reworked materials of variable thickness. The observed fault and fracture systems, partially inherited from regional structural setting and exhumed during volcanism and ground deformation episodes also seems to strongly control wave propagation, affecting the noise polarization properties.

show abstract

“…The very shallow layers are characterized by only minor lateral velocity variations and the obtained S-wave velocities take standardized values of loose and unconsolidated pyroclastic deposits (Nunziata et al 1999). For the northwestern sector of the studied area, close to the vegetation cover and associated background values of ground temperature and gas flux, the topmost layers are characterized by rather low-velocity values.…”

Section: Discussionmentioning

confidence: 76%

A 3D algorithm based on the combined inversion of Rayleigh and Love waves for imaging and monitoring of shallow structures

2017

View full text Add to dashboard Cite

S U M M A R YIn recent years, there has been increasing interest in the study of seismic noise interferometry as it can provide a complementary approach to active source or earthquake-based methods for imaging and continuous monitoring the shallow structure of the Earth. This meaningful information is extracted from wavefields propagating between those receiver positions at which seismic noise was recorded. Until recently, noise-based imaging relied mostly on Rayleigh waves. However, considering similar wavelengths, a combined use of Rayleigh and Love wave tomography can succeed in retrieving velocity heterogeneities at depth due to their different sensitivity kernels. Here, we present a novel one-step algorithm for simultaneously inverting Rayleigh and Love wave dispersion data aiming at identifying and describing complex 3-D velocity structures. The algorithm may help to accurately and efficiently map the shear wave velocities and the Poisson ratio of the surficial soil layers. In the high-frequency range, the scattered part of the correlation functions stabilizes sufficiently fast to provide a reliable estimate of the velocity structure not only for imaging purposes but also allows for changes in the medium properties to be monitored. Such monitoring can be achieved with a high spatial resolution in 3-D and with a time resolution as small as a few hours. In this paper, we describe a recent array experiment in a volcanic environment in Solfatara (Italy) and we show that this novel approach has identified strong velocity variations at the interface between liquids and gas-dominated reservoirs, allowing localizing a region which is highly dynamic due to the interaction between the deep convection and its surroundings.

show abstract

Shear wave velocities and primary influencing factors of Campi Flegrei–Neapolitan deposits

Cited by 16 publications

References 11 publications

Carbon dioxide diffuse degassing and estimation of heat release from volcanic and hydrothermal systems

Carbon dioxide diffuse degassing and estimation of heat release from volcanic and hydrothermal systems

Subsurface structure of the Solfatara volcano (Campi Flegrei caldera, Italy) as deduced from joint seismic‐noise array, volcanological and morphostructural analysis

A 3D algorithm based on the combined inversion of Rayleigh and Love waves for imaging and monitoring of shallow structures

Contact Info

Product

Resources

About