A WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONS
This paper is a comparison, on a worldwide scale, between P-station corrections deduced from ISC residuals (Dziewonski and Anderson) and synthetic S-station corrections computed using a three-dimensional upper mantle model obtained from mantle wave data (Woodhouse and Dziewonski). The upper mantle S...
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| Format: | Journal article |
| Language: | English |
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1985
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| _version_ | 1826302591226609664 |
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| author | Souriau, A Woodhouse, J |
| author_facet | Souriau, A Woodhouse, J |
| author_sort | Souriau, A |
| collection | OXFORD |
| description | This paper is a comparison, on a worldwide scale, between P-station corrections deduced from ISC residuals (Dziewonski and Anderson) and synthetic S-station corrections computed using a three-dimensional upper mantle model obtained from mantle wave data (Woodhouse and Dziewonski). The upper mantle S-velocity model is described by a spherical harmonic expansion up to degree 8; the P-station corrections are smoothed using a similar expansion, in order that the two data sets can be compared. Correlations between P-station corrections, δtP, and synthetic S-station corrections, δtS relevant to various depths of integration indicate that a station correction contains information about structures down to at least 670 km. For this depth of integration, the correlation coefficient of the two data sets is 0.59; the slope 'a' of the relation δtS = aδtP + b, obtained for the worldwide distribution of stations, is in good agreement with results of previous regional studies using direct readings of P and S arrival times (a = 3.61 ± 0.13). An analysis of regional variations of the relation δtS = aδtP + b is carried out on the basis of two published global tectonic patterns (Okal; Jodan). Results for oceanic regions are not reliable, due to the lack of data. On continental areas, a significant difference appears between mountains (a = 2.7 ± 0.3) and shields (a = 4.5 ± 0.4 for Okal's pattern, a = 5.7 ± 1.5 for Jordan's pattern). The largest a-value for shields rules out an explanation by partial melting, as proposed in previous studies. Thermal heterogeneities lead to low a-values; undulations of the lithosphere-asthenosphere boundary appear to be the most feasible explanation of the high slope beneath shields; they are also able to explain the range of variation of the station corrections; the lowest values of the station corrections correspond to a total vanishing of the low velocity zone beneath the oldest shields. For mountains, the mean values of the station corrections as well as the low a-value can be accounted for by a slight increase of Poisson's ratio together with a significant density increase. © 1985. |
| first_indexed | 2024-03-07T05:49:54Z |
| format | Journal article |
| id | oxford-uuid:e88082fc-55c1-4275-88b0-04db5a645804 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:49:54Z |
| publishDate | 1985 |
| record_format | dspace |
| spelling | oxford-uuid:e88082fc-55c1-4275-88b0-04db5a6458042022-03-27T10:47:16ZA WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONSJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:e88082fc-55c1-4275-88b0-04db5a645804EnglishSymplectic Elements at Oxford1985Souriau, AWoodhouse, JThis paper is a comparison, on a worldwide scale, between P-station corrections deduced from ISC residuals (Dziewonski and Anderson) and synthetic S-station corrections computed using a three-dimensional upper mantle model obtained from mantle wave data (Woodhouse and Dziewonski). The upper mantle S-velocity model is described by a spherical harmonic expansion up to degree 8; the P-station corrections are smoothed using a similar expansion, in order that the two data sets can be compared. Correlations between P-station corrections, δtP, and synthetic S-station corrections, δtS relevant to various depths of integration indicate that a station correction contains information about structures down to at least 670 km. For this depth of integration, the correlation coefficient of the two data sets is 0.59; the slope 'a' of the relation δtS = aδtP + b, obtained for the worldwide distribution of stations, is in good agreement with results of previous regional studies using direct readings of P and S arrival times (a = 3.61 ± 0.13). An analysis of regional variations of the relation δtS = aδtP + b is carried out on the basis of two published global tectonic patterns (Okal; Jodan). Results for oceanic regions are not reliable, due to the lack of data. On continental areas, a significant difference appears between mountains (a = 2.7 ± 0.3) and shields (a = 4.5 ± 0.4 for Okal's pattern, a = 5.7 ± 1.5 for Jordan's pattern). The largest a-value for shields rules out an explanation by partial melting, as proposed in previous studies. Thermal heterogeneities lead to low a-values; undulations of the lithosphere-asthenosphere boundary appear to be the most feasible explanation of the high slope beneath shields; they are also able to explain the range of variation of the station corrections; the lowest values of the station corrections correspond to a total vanishing of the low velocity zone beneath the oldest shields. For mountains, the mean values of the station corrections as well as the low a-value can be accounted for by a slight increase of Poisson's ratio together with a significant density increase. © 1985. |
| spellingShingle | Souriau, A Woodhouse, J A WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONS |
| title | A WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONS |
| title_full | A WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONS |
| title_fullStr | A WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONS |
| title_full_unstemmed | A WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONS |
| title_short | A WORLDWIDE COMPARISON OF PREDICTED S-WAVE DELAYS FROM A 3-DIMENSIONAL UPPER MANTLE MODEL WITH P-WAVE STATION CORRECTIONS |
| title_sort | worldwide comparison of predicted s wave delays from a 3 dimensional upper mantle model with p wave station corrections |
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