Small scale shallow attenuation structure at Mt. Vesuvius, Italy

Edoardo Del Pezzo*, Francesca Bianco, Luca De Siena, Aldo Zollo

*Corresponding author for this work

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

We present a high resolution 3D model of S-wave attenuation (Q(S)(-1)) for the volcanic structure of Mt. Vesuvius. Data from 959 waveforms relative to 332 volcano-tectonic earthquakes located close to the crater axis in a depth range between 1 and 4 km (below the sea level) recorded at 6 three-component seismic stations were used for the inversion. We obtained the estimate of Q(S)(-1) for each source-station pair using a single-station method based on the normalization of the S-wave spectrum for the coda spectrum at 12s lapse time. This is a modification of the well known coda-normalization method to estimate the average Q(S)(-1) for a given area. We adopt a parabolic ray-tracing in the high resolution 3D velocity model which was previously estimated using almost the same data set; then we solve a linear inversion scheme using the L-squared norm with positive constraints in 900 m-side cubic blocks, obtaining the estimate of Q(S)(-1) for each block. Robusteness and stability of the results are tested changing in turn the input data set and the inversion technique. Resolution is tested with both checkerboard and spike tests. Results show that attenuation structure resembles the velocity structure, well reproducing the interface between the carbonates and the overlying volcanick rocks which form the volcano. Analysis is well resolved till to a depth of 4-5 km. Higher Q contrast is found for the block overlying the carbonate basement and close to the crater axis, almost cohincident with a positive P-wave velocity contrast located in the same volume and previously interpreted as the residual high density body related to the last eruptions of Mt. Vesuvius. We interpret this high-Q zone as the upper part of carbonate basement in which most of the high energy seismicity take place. The low-Q values found at shallow depth are interpreted as due to the high heterogeneity mainly caused by the mixing of lava layers and pyroclastic materials extruded during the last eruptions. (c) 2006 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)257-268
Number of pages12
JournalPhysics of the Earth and Planetary Interiors
Volume157
Issue number3-4
Early online date27 Jun 2006
DOIs
Publication statusPublished - 31 Aug 2006

Keywords

  • attenuation tomography
  • Mt. Vesuvius
  • coda normalization method
  • velocity structure
  • Mount-Vesuvius
  • volcano
  • waves

Cite this

Small scale shallow attenuation structure at Mt. Vesuvius, Italy. / Del Pezzo, Edoardo; Bianco, Francesca; De Siena, Luca; Zollo, Aldo.

In: Physics of the Earth and Planetary Interiors, Vol. 157, No. 3-4, 31.08.2006, p. 257-268.

Research output: Contribution to journalArticle

Del Pezzo, Edoardo ; Bianco, Francesca ; De Siena, Luca ; Zollo, Aldo. / Small scale shallow attenuation structure at Mt. Vesuvius, Italy. In: Physics of the Earth and Planetary Interiors. 2006 ; Vol. 157, No. 3-4. pp. 257-268.
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T1 - Small scale shallow attenuation structure at Mt. Vesuvius, Italy

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AU - De Siena, Luca

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N2 - We present a high resolution 3D model of S-wave attenuation (Q(S)(-1)) for the volcanic structure of Mt. Vesuvius. Data from 959 waveforms relative to 332 volcano-tectonic earthquakes located close to the crater axis in a depth range between 1 and 4 km (below the sea level) recorded at 6 three-component seismic stations were used for the inversion. We obtained the estimate of Q(S)(-1) for each source-station pair using a single-station method based on the normalization of the S-wave spectrum for the coda spectrum at 12s lapse time. This is a modification of the well known coda-normalization method to estimate the average Q(S)(-1) for a given area. We adopt a parabolic ray-tracing in the high resolution 3D velocity model which was previously estimated using almost the same data set; then we solve a linear inversion scheme using the L-squared norm with positive constraints in 900 m-side cubic blocks, obtaining the estimate of Q(S)(-1) for each block. Robusteness and stability of the results are tested changing in turn the input data set and the inversion technique. Resolution is tested with both checkerboard and spike tests. Results show that attenuation structure resembles the velocity structure, well reproducing the interface between the carbonates and the overlying volcanick rocks which form the volcano. Analysis is well resolved till to a depth of 4-5 km. Higher Q contrast is found for the block overlying the carbonate basement and close to the crater axis, almost cohincident with a positive P-wave velocity contrast located in the same volume and previously interpreted as the residual high density body related to the last eruptions of Mt. Vesuvius. We interpret this high-Q zone as the upper part of carbonate basement in which most of the high energy seismicity take place. The low-Q values found at shallow depth are interpreted as due to the high heterogeneity mainly caused by the mixing of lava layers and pyroclastic materials extruded during the last eruptions. (c) 2006 Elsevier B.V. All rights reserved.

AB - We present a high resolution 3D model of S-wave attenuation (Q(S)(-1)) for the volcanic structure of Mt. Vesuvius. Data from 959 waveforms relative to 332 volcano-tectonic earthquakes located close to the crater axis in a depth range between 1 and 4 km (below the sea level) recorded at 6 three-component seismic stations were used for the inversion. We obtained the estimate of Q(S)(-1) for each source-station pair using a single-station method based on the normalization of the S-wave spectrum for the coda spectrum at 12s lapse time. This is a modification of the well known coda-normalization method to estimate the average Q(S)(-1) for a given area. We adopt a parabolic ray-tracing in the high resolution 3D velocity model which was previously estimated using almost the same data set; then we solve a linear inversion scheme using the L-squared norm with positive constraints in 900 m-side cubic blocks, obtaining the estimate of Q(S)(-1) for each block. Robusteness and stability of the results are tested changing in turn the input data set and the inversion technique. Resolution is tested with both checkerboard and spike tests. Results show that attenuation structure resembles the velocity structure, well reproducing the interface between the carbonates and the overlying volcanick rocks which form the volcano. Analysis is well resolved till to a depth of 4-5 km. Higher Q contrast is found for the block overlying the carbonate basement and close to the crater axis, almost cohincident with a positive P-wave velocity contrast located in the same volume and previously interpreted as the residual high density body related to the last eruptions of Mt. Vesuvius. We interpret this high-Q zone as the upper part of carbonate basement in which most of the high energy seismicity take place. The low-Q values found at shallow depth are interpreted as due to the high heterogeneity mainly caused by the mixing of lava layers and pyroclastic materials extruded during the last eruptions. (c) 2006 Elsevier B.V. All rights reserved.

KW - attenuation tomography

KW - Mt. Vesuvius

KW - coda normalization method

KW - velocity structure

KW - Mount-Vesuvius

KW - volcano

KW - waves

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JF - Physics of the Earth and Planetary Interiors

SN - 0031-9201

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ER -