Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies
<p>Sensitivity kernels or partial derivatives of phase velocity (<em>c</em>) and group velocity (<em>U</em>) with respect to medium parameters are useful to interpret a given set of observed surface wave velocity data. In addition to phase velocities, group velocities a...
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| Format: | Article |
| Language: | English |
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Istituto Nazionale di Geofisica e Vulcanologia (INGV)
2015-11-01
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| Series: | Annals of Geophysics |
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| Online Access: | http://www.annalsofgeophysics.eu/index.php/annals/article/view/6806 |
| _version_ | 1818306904989892608 |
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| author | Sankar N. Bhattacharya |
| author_facet | Sankar N. Bhattacharya |
| author_sort | Sankar N. Bhattacharya |
| collection | DOAJ |
| description | <p>Sensitivity kernels or partial derivatives of phase velocity (<em>c</em>) and group velocity (<em>U</em>) with respect to medium parameters are useful to interpret a given set of observed surface wave velocity data. In addition to phase velocities, group velocities are also being observed to find the radial anisotropy of the crust and mantle. However, sensitivities of group velocity for a radially anisotropic Earth have rarely been studied. Here we show sensitivities of group velocity along with those of phase velocity to the medium parameters <em>V<sub>SV</sub>, V<sub>SH </sub>, V<sub>PV</sub>, V<sub>PH , </sub></em><em>h</em><em> </em>and density in a radially anisotropic spherical Earth. The peak sensitivities for <em>U</em> are generally twice of those for <em>c</em>; thus <em>U</em> is more efficient than <em>c</em> to explore anisotropic nature of the medium. Love waves mainly depends on <em>V<sub>SH</sub></em> while Rayleigh waves is nearly independent of <em>V<sub>SH</sub></em> . The sensitivities show that there are trade-offs among these parameters during inversion and there is a need to reduce the number of parameters to be evaluated independently. It is suggested to use a nonlinear inversion jointly for Rayleigh and Love waves; in such a nonlinear inversion best solutions are obtained among the model parameters within prescribed limits for each parameter. We first choose <em>V<sub>SH</sub></em>, <em>V<sub>SV </sub></em>and <em>V<sub>PH</sub></em> within their corresponding limits; <em>V<sub>PV</sub></em> and <em>h</em> can be evaluated from empirical relations among the parameters. The density has small effect on surface wave velocities and it can be considered from other studies or from empirical relation of density to average P-wave velocity.</p> |
| first_indexed | 2024-12-13T06:49:54Z |
| format | Article |
| id | doaj.art-1327a15483964b57988ea2a15fbedaae |
| institution | Directory Open Access Journal |
| issn | 1593-5213 2037-416X |
| language | English |
| last_indexed | 2024-12-13T06:49:54Z |
| publishDate | 2015-11-01 |
| publisher | Istituto Nazionale di Geofisica e Vulcanologia (INGV) |
| record_format | Article |
| series | Annals of Geophysics |
| spelling | doaj.art-1327a15483964b57988ea2a15fbedaae2022-12-21T23:56:11ZengIstituto Nazionale di Geofisica e Vulcanologia (INGV)Annals of Geophysics1593-52132037-416X2015-11-0158510.4401/ag-68066052Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategiesSankar N. Bhattacharya0Lithosphere Study Centre, New Delhi,<p>Sensitivity kernels or partial derivatives of phase velocity (<em>c</em>) and group velocity (<em>U</em>) with respect to medium parameters are useful to interpret a given set of observed surface wave velocity data. In addition to phase velocities, group velocities are also being observed to find the radial anisotropy of the crust and mantle. However, sensitivities of group velocity for a radially anisotropic Earth have rarely been studied. Here we show sensitivities of group velocity along with those of phase velocity to the medium parameters <em>V<sub>SV</sub>, V<sub>SH </sub>, V<sub>PV</sub>, V<sub>PH , </sub></em><em>h</em><em> </em>and density in a radially anisotropic spherical Earth. The peak sensitivities for <em>U</em> are generally twice of those for <em>c</em>; thus <em>U</em> is more efficient than <em>c</em> to explore anisotropic nature of the medium. Love waves mainly depends on <em>V<sub>SH</sub></em> while Rayleigh waves is nearly independent of <em>V<sub>SH</sub></em> . The sensitivities show that there are trade-offs among these parameters during inversion and there is a need to reduce the number of parameters to be evaluated independently. It is suggested to use a nonlinear inversion jointly for Rayleigh and Love waves; in such a nonlinear inversion best solutions are obtained among the model parameters within prescribed limits for each parameter. We first choose <em>V<sub>SH</sub></em>, <em>V<sub>SV </sub></em>and <em>V<sub>PH</sub></em> within their corresponding limits; <em>V<sub>PV</sub></em> and <em>h</em> can be evaluated from empirical relations among the parameters. The density has small effect on surface wave velocities and it can be considered from other studies or from empirical relation of density to average P-wave velocity.</p>http://www.annalsofgeophysics.eu/index.php/annals/article/view/6806Crust-mantle structureRadial anisotropySurface waves |
| spellingShingle | Sankar N. Bhattacharya Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies Annals of Geophysics Crust-mantle structure Radial anisotropy Surface waves |
| title | Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies |
| title_full | Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies |
| title_fullStr | Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies |
| title_full_unstemmed | Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies |
| title_short | Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies |
| title_sort | sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical earth and inversion strategies |
| topic | Crust-mantle structure Radial anisotropy Surface waves |
| url | http://www.annalsofgeophysics.eu/index.php/annals/article/view/6806 |
| work_keys_str_mv | AT sankarnbhattacharya sensitivitiesofsurfacewavevelocitiestothemediumparametersinaradiallyanisotropicsphericalearthandinversionstrategies |