Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust
Data from four three-component ocean bottom seismographs (OBS) situated on a 145 km long profile on the Røst High on the continental shelf off Lofoten, northern Norway, have been modelled using 2-D seismic ray tracing, and a P - and S -wave velocity model along the profile is presented. The S -wave...
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1992
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fthighwire:oai:open-archive.highwire.org:gji:110/2/283 2023-05-15T17:08:16+02:00 Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust Mjelde, Rolf 1992-08-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/110/2/283 https://doi.org/10.1111/j.1365-246X.1992.tb00874.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/110/2/283 http://dx.doi.org/10.1111/j.1365-246X.1992.tb00874.x Copyright (C) 1992, Oxford University Press Articles TEXT 1992 fthighwire https://doi.org/10.1111/j.1365-246X.1992.tb00874.x 2016-11-16T16:49:53Z Data from four three-component ocean bottom seismographs (OBS) situated on a 145 km long profile on the Røst High on the continental shelf off Lofoten, northern Norway, have been modelled using 2-D seismic ray tracing, and a P - and S -wave velocity model along the profile is presented. The S -wave model has been obtained from a study of the high quality, horizontal component data. A V p / V s ratio of 1.95–2.15 is found in the sedimentary layers on the Røst High. These high values are consistent with shaly sediments, which are identified in dredged bedrock samples. South of the Røst High a considerably lower V p / V s ratio (ca. 1.6) is estimated for the sediments, which can be attributed in part to a higher degree of compaction in the deepest sediments and in part to a more sandy lithology. In the upper and middle crystalline crust a V p / V s ratio of 1.75 is obtained. Strong S reflections and P -to- S conversions at the Moho are observed on all four instruments, and the modelling of these arrivals indicates that the S -wave velocity in the lower crust varies with angle of incidence, from 3.5 km s-1 ( V p / V s = 1.95) at vertical incidence to 4.0 km s-1 ( V p / V s = 1.7) at 60–70°. This angle of incidence dependent S -wave anisotropy (the order of 10 per cent) is consistent with some horizontal or subhorizontal layering in the lower crust. Text Lofoten Northern Norway Røst HighWire Press (Stanford University) Lofoten Norway Røst ENVELOPE(11.983,11.983,67.467,67.467) Geophysical Journal International 110 2 283 296 |
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English |
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Articles Mjelde, Rolf Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust |
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Articles |
description |
Data from four three-component ocean bottom seismographs (OBS) situated on a 145 km long profile on the Røst High on the continental shelf off Lofoten, northern Norway, have been modelled using 2-D seismic ray tracing, and a P - and S -wave velocity model along the profile is presented. The S -wave model has been obtained from a study of the high quality, horizontal component data. A V p / V s ratio of 1.95–2.15 is found in the sedimentary layers on the Røst High. These high values are consistent with shaly sediments, which are identified in dredged bedrock samples. South of the Røst High a considerably lower V p / V s ratio (ca. 1.6) is estimated for the sediments, which can be attributed in part to a higher degree of compaction in the deepest sediments and in part to a more sandy lithology. In the upper and middle crystalline crust a V p / V s ratio of 1.75 is obtained. Strong S reflections and P -to- S conversions at the Moho are observed on all four instruments, and the modelling of these arrivals indicates that the S -wave velocity in the lower crust varies with angle of incidence, from 3.5 km s-1 ( V p / V s = 1.95) at vertical incidence to 4.0 km s-1 ( V p / V s = 1.7) at 60–70°. This angle of incidence dependent S -wave anisotropy (the order of 10 per cent) is consistent with some horizontal or subhorizontal layering in the lower crust. |
format |
Text |
author |
Mjelde, Rolf |
author_facet |
Mjelde, Rolf |
author_sort |
Mjelde, Rolf |
title |
Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust |
title_short |
Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust |
title_full |
Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust |
title_fullStr |
Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust |
title_full_unstemmed |
Shear waves from three-component ocean bottom seismographs off Lofoten, Norway, indicative of anisotropy in the lower crust |
title_sort |
shear waves from three-component ocean bottom seismographs off lofoten, norway, indicative of anisotropy in the lower crust |
publisher |
Oxford University Press |
publishDate |
1992 |
url |
http://gji.oxfordjournals.org/cgi/content/short/110/2/283 https://doi.org/10.1111/j.1365-246X.1992.tb00874.x |
long_lat |
ENVELOPE(11.983,11.983,67.467,67.467) |
geographic |
Lofoten Norway Røst |
geographic_facet |
Lofoten Norway Røst |
genre |
Lofoten Northern Norway Røst |
genre_facet |
Lofoten Northern Norway Røst |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/110/2/283 http://dx.doi.org/10.1111/j.1365-246X.1992.tb00874.x |
op_rights |
Copyright (C) 1992, Oxford University Press |
op_doi |
https://doi.org/10.1111/j.1365-246X.1992.tb00874.x |
container_title |
Geophysical Journal International |
container_volume |
110 |
container_issue |
2 |
container_start_page |
283 |
op_container_end_page |
296 |
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1766063983882665984 |