Acoustic imagery, southern Queen Charlotte margin

Davis, E; Currie, R G; Sawyer, B

doi:10.4095/133936

Cited by 3 publications

(4 citation statements)

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“…The QCF traces as mapped by Rohr (2015) and Brothers et al (2020) are identical north of 52.4 • N and display deviations only southward of it 8d). In our own morphology assessment using available high-resolution multibeam swath bathymetry (Barrie et al, 2013) and SeaMARC II sidescan sonar data (Davis et al, 1987), the deviations begin south of ∼52.6 • N (Fig. 8b,d).…”

Section: Constraints On the Queen Charlotte Fault Systemmentioning

confidence: 81%

“…Dashed black lines with teeth follow the trough representing the surface trace of the HGT, solid black lines are scarps associated with the Queen Charlotte Fault (QCF: dashed where inferred/uncertain), and dashed black lines with diamonds are the crests of surface folds. c) SeaMARC II sidescan sonar data (Davis et al, 1987) sistent with the distribution of coseismic HGT slip (3-6 m slip contours from Lay et al, 2013), and may also coincide with the source of the coseismic high frequency body wave energy modeled by Lay et al (2013).…”

Section: Reinterpreting Postseismic Earthquakesmentioning

confidence: 86%

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A complex Queen Charlotte Plate Boundary offshore Haida Gwaii

Oliva,

Bostock,

Schaeffer

et al. 2023

Preprint

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The Queen Charlotte plate boundary marks a transpressional system between the Pacific and North American plates, extending from offshore Haida Gwaii in Canada into southeastern Alaska. Using continuous seismic waveforms from temporary and permanent seismic networks from 1998–2020, we produced a comprehensive catalog of ~50,000 earthquakes across the region near Haida Gwaii. We used an automated processing technique of auto-regressive phase detection and onset estimation to obtain the initial seismic catalog, integrated existing catalogs, inverted for 3D velocity structure using data from the most well constrained period, and relocated the entire catalog using the new 3D velocity model. We investigate the seismically active sections of the transcurrent Queen Charlotte fault (QCF), noting that little seismicity locates directly along the bathymetrically defined QCF trace. Instead, the seismicity illuminates a complex system of multiple segmented structures, featuring variable geometries along strike. Clustered shallow seismicity could indicate active shallow faults within the highly deformed Queen Charlotte terrace. Few aftershocks appear on the thrust plane of the 2012 Mw 7.8 Haida Gwaii earthquake except near its inferred intersection with the QCF between 15 and 20 km depths, suggesting elevated residual stress. Deep (up to ~20 km) crustal seismicity below central Haida Gwaii aligned parallel to the strike of the thrust plane may manifest the landward underthrusting of the Pacific plate. We also explore the possibility of coseismic strike-slip rupture on the QCF during the 2012 earthquake. Our results provide insights into postseismic strain accommodation and partitioning across this complex oblique transpressive system.

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Section: Constraints On the Queen Charlotte Fault Systemmentioning

confidence: 81%

Section: Reinterpreting Postseismic Earthquakesmentioning

confidence: 86%

A complex Queen Charlotte Plate Boundary offshore Haida Gwaii

Oliva,

Bostock,

Schaeffer

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Dashed black lines with teeth follow the trough representing the surface trace of the HGT, solid black lines are scarps associated with the Queen Charlotte Fault (QCF: dashed where inferred/uncertain), and dashed black lines with diamonds are the crests of surface folds. (c) SeaMARC II sidescan sonar data (Davis et al., 1987) overlain by the high‐resolution bathymetry showing the surface morphology offshore Moresby Island. (d) Same map as (c) with earthquakes colored by depth, mapped strands of the QCF from previous studies, and new strands identified in this study.…”

Section: Discussionmentioning

confidence: 99%

“…The QCF traces as mapped by Rohr (2015) and Brothers et al (2020) are identical north of 52.4°N and display deviations only southward of it (around D-D' in Figures 3 and 8d). In our own morphology assessment using available high-resolution multibeam swath bathymetry (Barrie et al, 2013) and SeaMARC II sidescan sonar data (Davis et al, 1987), the deviations begin south of ∼52.6°N (Figures 8b and 8d). Figures 8a and 8b provide an expanded view of the bathymetry in the northern region and its relation to seismicity.…”

Section: Constraints On the Queen Charlotte Fault Systemmentioning

confidence: 93%

Incipient Subduction and Slip Partitioning at High Obliquity: The Haida Gwaii Plate Boundary

Oliva,

Bostock,

Schaeffer

et al. 2024

JGR Solid Earth

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Plate motion obliquity along the dominantly transform Queen Charlotte plate boundary (QCPB) peaks offshore Haida Gwaii. To investigate the effects of obliquity on plate boundary deformation, we analyze continuous seismic waveforms from temporary and permanent stations from 1998 to 2020 to generate a catalog of ∼50,000 earthquakes across Haida Gwaii. We use an automated technique based on auto‐regressive phase detection and onset estimation to obtain the initial seismic catalog, integrate existing catalogs, invert for 3D velocity structure using data from the best constrained period, and relocate the entire catalog using the new 3D velocity model. We investigate the seismically active sections of the transcurrent Queen Charlotte fault (QCF), noting that little seismicity locates directly along its bathymetrically defined trace. Instead, seismicity illuminates a complex system of segmented structures with variable geometries along strike. Other clusters highlight active shallow faults within the highly deformed Queen Charlotte terrace. Few aftershocks appear on the thrust plane of the 2012 Mw 7.8 Haida Gwaii earthquake except near its inferred intersection with the QCF at 15–20 km depths, suggesting elevated residual stress at the juncture of slip‐partitioning. Deep crustal seismicity (up to ∼20 km depths) beneath central Haida Gwaii aligned parallel to the strike of the thrust plane may represent landward underthrusting of the Pacific plate. Our results suggest possible coseismic strike‐slip rupture on the QCF during the 2012 earthquake and add support to the thesis that highly oblique transform boundaries are viable settings for subduction initiation.

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Plate Boundary Adjustments of the Southernmost Queen Charlotte Fault

Rohr¹

2015

Bulletin of the Seismological Society of America

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Acoustic imagery, southern Queen Charlotte margin

Cited by 3 publications

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A complex Queen Charlotte Plate Boundary offshore Haida Gwaii

A complex Queen Charlotte Plate Boundary offshore Haida Gwaii

Incipient Subduction and Slip Partitioning at High Obliquity: The Haida Gwaii Plate Boundary

Plate Boundary Adjustments of the Southernmost Queen Charlotte Fault

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