Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation
International audience One of the most robust observations for the inner core rotation is that the differential PKP BC-DF traveltimes from South Sandwich Islands (SSI) earthquakes to College, Alaska (and some other stations in Alaska), have increased systematically over the past 50 years. The time s...
Published in: | Journal of Geophysical Research: Solid Earth |
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Main Authors: | , , |
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Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2006
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Online Access: | https://insu.hal.science/insu-00270306 https://insu.hal.science/insu-00270306/document https://insu.hal.science/insu-00270306/file/2005JB004175.pdf https://doi.org/10.1029/2005JB004175 |
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Open Polar |
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Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
systematic earthquake mislocation P residuals inner core rotation [SDU]Sciences of the Universe [physics] |
spellingShingle |
systematic earthquake mislocation P residuals inner core rotation [SDU]Sciences of the Universe [physics] Sun, Xinlei Poupinet, Georges Song, Xiaodong Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation |
topic_facet |
systematic earthquake mislocation P residuals inner core rotation [SDU]Sciences of the Universe [physics] |
description |
International audience One of the most robust observations for the inner core rotation is that the differential PKP BC-DF traveltimes from South Sandwich Islands (SSI) earthquakes to College, Alaska (and some other stations in Alaska), have increased systematically over the past 50 years. The time shift in the differential time residuals is some 0.3 s over 30 years. This temporal change is thought to result from a shift of the inner core structure from a superrotation of the inner core. However, the observation has been hotly debated and has been suggested to be an artifact of systematic earthquake mislocation. Here we examine this issue using three mutually independent approaches, with a goal to quantify the amount of the systematic mislocation, if any. All three approaches involve differencing data between north stations at a similar azimuth as the SSI-Alaska azimuth and south stations at nearly the opposite azimuth. Mislocation along this azimuth has greatest impact on the PKP differential times. In approach 1, we examine how the double difference of P traveltimes between a north station and a south station changes with time. Because the differential apparent slowness between the P traveltimes of the pairs is 8 to 16 times that of the differential BC-DF times, mislocation would cause a time shift in the double difference an order of magnitude larger than that of BC-DF times. In approach 2, we compare directly difference in P arrival times between two SSI events that are close by and between a north and a south stations, which avoids using earthquake locations and Earth models entirely. In approach 3, we compare PKP traveltime residuals between a group of north and south stations. Because PKP traveltimes are generally not used for location in earthquake bulletins, they provide an independent data set to check earthquake location errors. The results from approaches 1 and 2, both of which use P data, are generally consistent. The mislocation is up to 3.6 ± 4.2 km (one standard deviation), explaining less than ... |
author2 |
Department of Geology University of Illinois at Urbana-Champaign Urbana (UIUC) University of Illinois System-University of Illinois System Laboratoire de Géophysique Interne et Tectonophysique (LGIT) Observatoire des Sciences de l'Univers de Grenoble (OSUG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Sun, Xinlei Poupinet, Georges Song, Xiaodong |
author_facet |
Sun, Xinlei Poupinet, Georges Song, Xiaodong |
author_sort |
Sun, Xinlei |
title |
Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation |
title_short |
Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation |
title_full |
Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation |
title_fullStr |
Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation |
title_full_unstemmed |
Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation |
title_sort |
examination of systematic mislocation of south sandwich islands earthquakes using station pairs: implications for inner core rotation |
publisher |
HAL CCSD |
publishDate |
2006 |
url |
https://insu.hal.science/insu-00270306 https://insu.hal.science/insu-00270306/document https://insu.hal.science/insu-00270306/file/2005JB004175.pdf https://doi.org/10.1029/2005JB004175 |
genre |
South Sandwich Islands Alaska |
genre_facet |
South Sandwich Islands Alaska |
op_source |
ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://insu.hal.science/insu-00270306 Journal of Geophysical Research : Solid Earth, 2006, 111, pp.B11305. ⟨10.1029/2005JB004175⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2005JB004175 insu-00270306 https://insu.hal.science/insu-00270306 https://insu.hal.science/insu-00270306/document https://insu.hal.science/insu-00270306/file/2005JB004175.pdf doi:10.1029/2005JB004175 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1029/2005JB004175 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
111 |
container_issue |
B11 |
container_start_page |
n/a |
op_container_end_page |
n/a |
_version_ |
1797570231945658368 |
spelling |
ftinsu:oai:HAL:insu-00270306v1 2024-04-28T08:38:59+00:00 Examination of systematic mislocation of South Sandwich Islands earthquakes using station pairs: Implications for inner core rotation Sun, Xinlei Poupinet, Georges Song, Xiaodong Department of Geology University of Illinois at Urbana-Champaign Urbana (UIUC) University of Illinois System-University of Illinois System Laboratoire de Géophysique Interne et Tectonophysique (LGIT) Observatoire des Sciences de l'Univers de Grenoble (OSUG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS) 2006 https://insu.hal.science/insu-00270306 https://insu.hal.science/insu-00270306/document https://insu.hal.science/insu-00270306/file/2005JB004175.pdf https://doi.org/10.1029/2005JB004175 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1029/2005JB004175 insu-00270306 https://insu.hal.science/insu-00270306 https://insu.hal.science/insu-00270306/document https://insu.hal.science/insu-00270306/file/2005JB004175.pdf doi:10.1029/2005JB004175 info:eu-repo/semantics/OpenAccess ISSN: 2169-9313 EISSN: 2169-9356 Journal of Geophysical Research : Solid Earth https://insu.hal.science/insu-00270306 Journal of Geophysical Research : Solid Earth, 2006, 111, pp.B11305. ⟨10.1029/2005JB004175⟩ systematic earthquake mislocation P residuals inner core rotation [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2006 ftinsu https://doi.org/10.1029/2005JB004175 2024-04-05T00:38:11Z International audience One of the most robust observations for the inner core rotation is that the differential PKP BC-DF traveltimes from South Sandwich Islands (SSI) earthquakes to College, Alaska (and some other stations in Alaska), have increased systematically over the past 50 years. The time shift in the differential time residuals is some 0.3 s over 30 years. This temporal change is thought to result from a shift of the inner core structure from a superrotation of the inner core. However, the observation has been hotly debated and has been suggested to be an artifact of systematic earthquake mislocation. Here we examine this issue using three mutually independent approaches, with a goal to quantify the amount of the systematic mislocation, if any. All three approaches involve differencing data between north stations at a similar azimuth as the SSI-Alaska azimuth and south stations at nearly the opposite azimuth. Mislocation along this azimuth has greatest impact on the PKP differential times. In approach 1, we examine how the double difference of P traveltimes between a north station and a south station changes with time. Because the differential apparent slowness between the P traveltimes of the pairs is 8 to 16 times that of the differential BC-DF times, mislocation would cause a time shift in the double difference an order of magnitude larger than that of BC-DF times. In approach 2, we compare directly difference in P arrival times between two SSI events that are close by and between a north and a south stations, which avoids using earthquake locations and Earth models entirely. In approach 3, we compare PKP traveltime residuals between a group of north and south stations. Because PKP traveltimes are generally not used for location in earthquake bulletins, they provide an independent data set to check earthquake location errors. The results from approaches 1 and 2, both of which use P data, are generally consistent. The mislocation is up to 3.6 ± 4.2 km (one standard deviation), explaining less than ... Article in Journal/Newspaper South Sandwich Islands Alaska Institut national des sciences de l'Univers: HAL-INSU Journal of Geophysical Research: Solid Earth 111 B11 n/a n/a |