| Titre | Temporal variations in coda Q before and after the 2017 Barrow Strait earthquake (Mw 5.9) in Nunavut and the 2012 Haida Gwaii earthquake (Mw 7.8) in British Columbia |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Farahbod, A M; Cassidy, J F |
| Source | Commission géologique du Canada, Dossier public 8930, 2022, 67p., https://doi.org/10.4095/331095  Accès ouvert |
| Image |  |
| Année | 2022 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/331095 |
| Media | numérique; en ligne |
| Formats | pdf |
| Province | Nunavut; Colombie-Britannique |
| SNRC | 103B; 103C; 103F; 103G; 58F; 58G; 68E/01; 68H/01; 68E/02; 68E/07; 68E/08; 68E/09; 68E/10; 68E/15; 68E/16; 68H/02; 68H/07; 68H/08; 68H/09; 68H/10; 68H/15; 68H/16 |
| Région | Haida Gwaii; Barrow Strait |
| Lat/Long OENS | -134.0000 -130.0000 54.0000 52.0000 |
| Lat/Long OENS | -98.0000 -92.0000 76.0000 74.0000 |
| Sujets | secousses séismiques; études séismiques; sismicité; séismologie; tectonique; géomathématique |
| Illustrations | cartes de localisation; images sismiques; profils sismiques; tableaux |
| Programme | Géoscience pour la sécurité publique Risques géologique du tremblement de terre |
| Diffusé | 2022 11 21 |
| Résumé | (disponible en anglais seulement)
In this study, we examine potential temporal changes in coda Q values for two significant Canadian earthquakes in different tectonic environments: the 2017 (Mw
5.9) Barrow Strait earthquake along Canada's northern margin and the 2012 (Mw 7.8) Haida Gwaii subduction earthquake on Canada's west coast. Waveforms from 124 earthquakes (2.0 <= M <= 4.6) for ~30 years prior to the January 8, 2017 Barrow Strait
earthquake and 66 events (mainly aftershocks of M 2.0-5.3) in about 4 years after the mainshock recorded by the closest seismic station (RES) of the Canadian National Seismograph Network (CNSN) were utilized in this study. Based on our analysis,
overall average of Q0 (Q at 1 Hz) decreased from 92 (before the mainshock) to 81. The most significant decrease in the frequency range between 2 and 16 Hz is observed for areas corresponding to ellipse parameter a2 of 50, 70 and 80 mainly related to
aftershock activity. Precursory Q changes could not be evaluated before the mainshock due to the lack of reported seismicity within 100 km of the recording seismic station for almost 2 years from April 2015 to January 2017. Coda Q values before and
after the October 28, 2012 Haida Gwaii earthquake in British Columbia show a similar pattern. Waveforms from 249 earthquakes (2.0 <= M <= 4.9) in 2 years before the mainshock and 498 events (2.5 <= M <= 6.3) in 2 years after the mainshock recorded by
the three closest seismic stations of the CNSN were utilized. Overall average of Q0 decreased from 89 (before the mainshock) to 69 (station BNB), from 90 to 79 (station DIB) and from 86 to 78 (station VIB). In general, these results are in agreement
with other global studies that show a decrease in Q0 following a major earthquake, likely the result of increased fracturing and fluids in the epicentral region. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Il s'agit de la première étude connue à examiner l'atténuation des ondes sismiques dans différents environnements tectoniques du Canada, et
comment l'atténuation change avant et après des séismes importants. Nous constatons qu'à la suite du tremblement de terre M5.9 du détroit de Barrow, NU et du tremblement de terre M7.8 Haida Gwaii, Colombie-Britannique, l'atténuation a augmenté - en
particulier aux stations les plus proches du tremblement de terre. Cela est probablement dû à une fracturation accrue de la roche et des fluides à proximité de la zone de faille. |
| GEOSCAN ID | 331095 |
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