| Title | An overview of seismic attenuation in the Eastern Canadian Arctic and the Hudson Bay Complex, Manitoba, Newfoundland and Labrador, Nunavut, Ontario, and Quebec |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Farahbod, A M; Cassidy, J F |
| Source | Geological Survey of Canada, Open File 8908, 2022, 47 pages, https://doi.org/10.4095/330396  Open Access |
| Image |  |
| Year | 2022 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | digital; on-line |
| File format | pdf |
| Province | Manitoba; Ontario; Quebec; Newfoundland and Labrador; Nunavut |
| NTS | 12M; 12N; 22M; 22N; 22O; 22P; 32M; 32N; 32O; 32P; 42M; 42N; 42O; 42P; 52M; 52N; 52O; 52P; 62O; 62P; 23; 33; 43; 53; 24; 34; 44; 54; 25; 35; 45; 55; 26; 36; 46; 56; 27A; 27B; 27C; 27D; 37A; 37B; 37C; 37D;
47A; 47B; 47C; 47D; 57A; 57B; 57C; 57D; 67A; 67D; 14; 15; 16; 13C; 13D; 13E; 13F; 13K; 13L; 13M; 13N; 63A; 63B; 63G; 63H; 63I; 63J; 63O; 63P; 64A; 64B; 64G; 64H; 64I; 64J; 64O; 64P; 65A; 65B; 65G; 65H; 65I; 65J; 65O; 65P; 66A; 66B; 66G; 66H; 66I;
66J; 66O; 66P |
| Area | Hudson Bay; Canadian Arctic; Canada |
| Lat/Long WENS | -100.0000 -60.0000 70.0000 51.0000 |
| Subjects | Science and Technology; geophysics; tectonics; Nature and Environment; seismicity; seismic waves; earthquake magnitudes; earthquake studies; earthquakes; s waves; Archean; Precambrian;
Proterozoic |
| Illustrations | location maps; tables; diagram |
| Program | Public Safety Geoscience Assessing Earthquake Geohazards |
| Released | 2022 07 20 |
| Abstract | In this study we investigated coda-wave attenuation (QC) from the eastern Canadian Arctic in Nunavut and the Hudson Bay complex including portions of northern Manitoba, Ontario, Quebec and Labrador. We
used earthquake recordings from 15 broadband and 3 short period seismograph stations of the Canadian National Seismic Network (CNSN) and 29 broadband stations of the POLARIS network across the region. Our dataset is comprised of 637 earthquakes
recorded between 1985 and 2021 with magnitudes ranging from 1.3 to 6.1, depths from 0 to 20 km and epicentral distances of 5 to 100 km. This gives a total of 246 high signal-to-noise (S/N) traces (S/N[lesser/equal]5.0) useful for QC calculation (with
a maximum ellipse parameter, a2, of 100) across the region. Coda windows were selected to start at tc = 2tS (two times the travel time of the direct S wave), and were filtered at center frequencies of 2, 4, 8, 12 and 16 Hz. Our study reveals a
consistent pattern. We find that in the northern section of the study area, the highest Q0 values (e.g., Q0 of 110 and 112) are at station POIN and station RES, respectively, which are located in the older Archean province. The lowest Q0 values that
we find (e.g., Q0 of 55 and 61) are at station AKVQ and IVKQ respectively, located in northern Quebec. Smaller Q0 values for stations in the south are explained by the younger age of the rocks and proximity to the main fault systems. An average for
all the data results in a Q relationship of QC = 82f1.08 for the frequency band of 2 to 16 Hz for the entire region. |
| Summary | (Plain Language Summary, not published)
We study the recordings of 637 earthquakes to determine how seismic waves attenuate in the eastern Canadian Arctic in Nunavut and the Hudson Bay complex
including portions of northern Manitoba, Ontario, Quebec and Labrador. This is a part of a national study, allowing us to make comparisons between all parts of the country - from regions of active plate tectonics and volcanic belts (west coast),
through the stable craton (much of central Canada) through the Appalachian and northern regions of Canada. We find that the highest seismic attenuation (more rapid dissipation of energy) occurs in northern Quebec closest to the major fault systems in
the Ungava Peninsula. In addition, we find a time-varying element to coda Q. The calculated Q0 at station RES demonstrates an overall decrease of 12% after the occurrence of the 2017 M6.1 earthquake in the region. This is similar to some worldwide
observations of a decrease in Q after a large earthquake. The results of this study improve our understanding of coda Q attenuation across Canada and links with earthquake hazard. |
| GEOSCAN ID | 330396 |
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