Comparison of Location Procedures: The Kara Sea Event of 16 August 1997
Various location procedures and velocity models are compared for the ML 3.3 Kara Sea event of 16 August 1997. This event has been the subject of considerable discussion because of its geographical position and the difficulty in obtaining a reliable focal-depth estimate. A comprehensive data set was...
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/35692 2024-01-14T10:08:18+01:00 Comparison of Location Procedures: The Kara Sea Event of 16 August 1997 Schweitzer, Johannes Kennett, Brian http://hdl.handle.net/1885/35692 https://doi.org/10.1785/0120040017 https://openresearch-repository.anu.edu.au/bitstream/1885/35692/5/BSSSA97_389.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/35692/7/01_Schweitzer_Comparison_of_Location_2007.pdf.jpg unknown Seismological Society of America 0037-1106 http://hdl.handle.net/1885/35692 doi:10.1785/0120040017 https://openresearch-repository.anu.edu.au/bitstream/1885/35692/5/BSSSA97_389.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/35692/7/01_Schweitzer_Comparison_of_Location_2007.pdf.jpg Bulletin of the Seismological Society of America Keywords: Earthquakes Mathematical models Seismic prospecting Seismic response Seismic waves Velocity Velocity measurement Geographical position Seismic source Velocity model Seismology algorithm data inversion data set earthquake focal mechanism lo Journal article ftanucanberra https://doi.org/10.1785/0120040017 2023-12-15T09:37:16Z Various location procedures and velocity models are compared for the ML 3.3 Kara Sea event of 16 August 1997. This event has been the subject of considerable discussion because of its geographical position and the difficulty in obtaining a reliable focal-depth estimate. A comprehensive data set was extracted by (re-)reading the records from all available stations. These readings have then been used in a sequence of location experiments to examine the effect of using different velocity models to describe the travel times of the phases, and also to compare the use of a fully nonlinear scheme (shakeNA; Sambridge and Kennett, 2001) and a linearized location algorithm (HYPOSAT; Schweitzer, 2001, 2002). A standard least-squares misfit criterion has been used for direct comparisons between the two methods. The results confirm both the importance of S-wave information in assessing the depth of regional events, and the need to apply a reliable velocity model to place the strongest constraints on the location of the event. Even with only a limited data set, but an adequate velocity model, it is possible to find the position of the Kara Sea event close to the most probable locations; however, there is then no depth resolution. Reported error ellipses from standard data centers tend to have relatively small error ellipses. With the commonly made assumption that the reading errors and the a posteriori residuals have an unbiased normal distribution, such inversion results may indicate an unreasonably high resolution and accuracy of the solution. The epicenter estimates for the whole data set using the range of different techniques agree quite well, with some overlap of the estimated confidence regions. The observed seismic source was most likely an earthquake in the middle or lower crust at about 10-30 km depth. Article in Journal/Newspaper Kara Sea Australian National University: ANU Digital Collections Kara Sea Kennett ENVELOPE(-65.167,-65.167,-67.117,-67.117) Bulletin of the Seismological Society of America 97 2 389 400 |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: Earthquakes Mathematical models Seismic prospecting Seismic response Seismic waves Velocity Velocity measurement Geographical position Seismic source Velocity model Seismology algorithm data inversion data set earthquake focal mechanism lo |
spellingShingle |
Keywords: Earthquakes Mathematical models Seismic prospecting Seismic response Seismic waves Velocity Velocity measurement Geographical position Seismic source Velocity model Seismology algorithm data inversion data set earthquake focal mechanism lo Schweitzer, Johannes Kennett, Brian Comparison of Location Procedures: The Kara Sea Event of 16 August 1997 |
topic_facet |
Keywords: Earthquakes Mathematical models Seismic prospecting Seismic response Seismic waves Velocity Velocity measurement Geographical position Seismic source Velocity model Seismology algorithm data inversion data set earthquake focal mechanism lo |
description |
Various location procedures and velocity models are compared for the ML 3.3 Kara Sea event of 16 August 1997. This event has been the subject of considerable discussion because of its geographical position and the difficulty in obtaining a reliable focal-depth estimate. A comprehensive data set was extracted by (re-)reading the records from all available stations. These readings have then been used in a sequence of location experiments to examine the effect of using different velocity models to describe the travel times of the phases, and also to compare the use of a fully nonlinear scheme (shakeNA; Sambridge and Kennett, 2001) and a linearized location algorithm (HYPOSAT; Schweitzer, 2001, 2002). A standard least-squares misfit criterion has been used for direct comparisons between the two methods. The results confirm both the importance of S-wave information in assessing the depth of regional events, and the need to apply a reliable velocity model to place the strongest constraints on the location of the event. Even with only a limited data set, but an adequate velocity model, it is possible to find the position of the Kara Sea event close to the most probable locations; however, there is then no depth resolution. Reported error ellipses from standard data centers tend to have relatively small error ellipses. With the commonly made assumption that the reading errors and the a posteriori residuals have an unbiased normal distribution, such inversion results may indicate an unreasonably high resolution and accuracy of the solution. The epicenter estimates for the whole data set using the range of different techniques agree quite well, with some overlap of the estimated confidence regions. The observed seismic source was most likely an earthquake in the middle or lower crust at about 10-30 km depth. |
format |
Article in Journal/Newspaper |
author |
Schweitzer, Johannes Kennett, Brian |
author_facet |
Schweitzer, Johannes Kennett, Brian |
author_sort |
Schweitzer, Johannes |
title |
Comparison of Location Procedures: The Kara Sea Event of 16 August 1997 |
title_short |
Comparison of Location Procedures: The Kara Sea Event of 16 August 1997 |
title_full |
Comparison of Location Procedures: The Kara Sea Event of 16 August 1997 |
title_fullStr |
Comparison of Location Procedures: The Kara Sea Event of 16 August 1997 |
title_full_unstemmed |
Comparison of Location Procedures: The Kara Sea Event of 16 August 1997 |
title_sort |
comparison of location procedures: the kara sea event of 16 august 1997 |
publisher |
Seismological Society of America |
url |
http://hdl.handle.net/1885/35692 https://doi.org/10.1785/0120040017 https://openresearch-repository.anu.edu.au/bitstream/1885/35692/5/BSSSA97_389.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/35692/7/01_Schweitzer_Comparison_of_Location_2007.pdf.jpg |
long_lat |
ENVELOPE(-65.167,-65.167,-67.117,-67.117) |
geographic |
Kara Sea Kennett |
geographic_facet |
Kara Sea Kennett |
genre |
Kara Sea |
genre_facet |
Kara Sea |
op_source |
Bulletin of the Seismological Society of America |
op_relation |
0037-1106 http://hdl.handle.net/1885/35692 doi:10.1785/0120040017 https://openresearch-repository.anu.edu.au/bitstream/1885/35692/5/BSSSA97_389.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/35692/7/01_Schweitzer_Comparison_of_Location_2007.pdf.jpg |
op_doi |
https://doi.org/10.1785/0120040017 |
container_title |
Bulletin of the Seismological Society of America |
container_volume |
97 |
container_issue |
2 |
container_start_page |
389 |
op_container_end_page |
400 |
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1788062728840019968 |