The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array
There is broad agreement among various seismological studies that the upper mantle has two regions where very high positive velocity gradients or transition zones exist. In most cases, the presence of these zones implies that two major triplications are likely to exist in the body-wave travel-time c...
Published in: | Canadian Journal of Earth Sciences |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
1978
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1139/e78-023 http://www.nrcresearchpress.com/doi/pdf/10.1139/e78-023 |
id |
crcansciencepubl:10.1139/e78-023 |
---|---|
record_format |
openpolar |
spelling |
crcansciencepubl:10.1139/e78-023 2023-12-17T10:51:30+01:00 The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array Ram, A. Mereu, R. F. Weichert, D. H. 1978 http://dx.doi.org/10.1139/e78-023 http://www.nrcresearchpress.com/doi/pdf/10.1139/e78-023 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 15, issue 2, page 227-236 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1978 crcansciencepubl https://doi.org/10.1139/e78-023 2023-11-19T13:38:46Z There is broad agreement among various seismological studies that the upper mantle has two regions where very high positive velocity gradients or transition zones exist. In most cases, the presence of these zones implies that two major triplications are likely to exist in the body-wave travel-time curve for distances less than 30°. Because of the difficulties in observing and identifying later arrivals belonging to the various travel-time branches, the inversion of the seismic data is often very difficult. In this paper an adaptive processing technique was employed to examine the variations in slowness that occur along the first 36 s of the short-period P-wave trains recorded at the Yellowknife medium aperture seismic array. Over 100 earthquakes from the Alaska Peninsula and California regions were selected. From the California results we were able to clearly observe the 12–13 s/deg slowness branch as a later arrival out to distances as great as 26°. Other later arrival branches as well as cusps associated with the 400 and 650 km discontinuities were not well defined even though the cross-over point as determined from slowness measurements on first arrivals were clearly located. An inversion of the data showed that the '650 km' transition zone occurred at a much shallower depth west of the array compared to the corresponding region to the south. Article in Journal/Newspaper Yellowknife Alaska Canadian Science Publishing (via Crossref) Yellowknife Canadian Journal of Earth Sciences 15 2 227 236 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Ram, A. Mereu, R. F. Weichert, D. H. The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array |
topic_facet |
General Earth and Planetary Sciences |
description |
There is broad agreement among various seismological studies that the upper mantle has two regions where very high positive velocity gradients or transition zones exist. In most cases, the presence of these zones implies that two major triplications are likely to exist in the body-wave travel-time curve for distances less than 30°. Because of the difficulties in observing and identifying later arrivals belonging to the various travel-time branches, the inversion of the seismic data is often very difficult. In this paper an adaptive processing technique was employed to examine the variations in slowness that occur along the first 36 s of the short-period P-wave trains recorded at the Yellowknife medium aperture seismic array. Over 100 earthquakes from the Alaska Peninsula and California regions were selected. From the California results we were able to clearly observe the 12–13 s/deg slowness branch as a later arrival out to distances as great as 26°. Other later arrival branches as well as cusps associated with the 400 and 650 km discontinuities were not well defined even though the cross-over point as determined from slowness measurements on first arrivals were clearly located. An inversion of the data showed that the '650 km' transition zone occurred at a much shallower depth west of the array compared to the corresponding region to the south. |
format |
Article in Journal/Newspaper |
author |
Ram, A. Mereu, R. F. Weichert, D. H. |
author_facet |
Ram, A. Mereu, R. F. Weichert, D. H. |
author_sort |
Ram, A. |
title |
The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array |
title_short |
The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array |
title_full |
The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array |
title_fullStr |
The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array |
title_full_unstemmed |
The identification and interpretation of upper mantle travel-time branches from measurements of d T /dΔ made on data recorded at the Yellowknife seismic array |
title_sort |
identification and interpretation of upper mantle travel-time branches from measurements of d t /dδ made on data recorded at the yellowknife seismic array |
publisher |
Canadian Science Publishing |
publishDate |
1978 |
url |
http://dx.doi.org/10.1139/e78-023 http://www.nrcresearchpress.com/doi/pdf/10.1139/e78-023 |
geographic |
Yellowknife |
geographic_facet |
Yellowknife |
genre |
Yellowknife Alaska |
genre_facet |
Yellowknife Alaska |
op_source |
Canadian Journal of Earth Sciences volume 15, issue 2, page 227-236 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e78-023 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
15 |
container_issue |
2 |
container_start_page |
227 |
op_container_end_page |
236 |
_version_ |
1785576787977175040 |