Transpression between two warm mafic plates: The Queen Charlotte Fault revisited

Rohr, Kristin M. M.; Scheidhauer, M.; Tréhu, Anne M.

doi:10.1029/1999jb900403

Cited by 61 publications

(108 citation statements)

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“…These features are all consistent with incipient subduction. Models have also been proposed in which all convergence is accommodated by shortening via thrust faulting on either side of the QCF extending through the crust (Hyndman and Ellis, 1981;Rohr et al, 2000). This model requires at least 80 km of crustal shortening (assuming a 4 my duration of 20 mm=yr convergence) over a width of 30-60 km within both the Pacific and North American plates (Crouch et al, 1984;Rohr et al, 2000), which is similar to the 14-72 km of transpression taken up along the San Andreas fault (Crouch et al, 1984).…”

Section: Queen Charlotte Fault Geometry and Convergencementioning

confidence: 99%

“…Models have also been proposed in which all convergence is accommodated by shortening via thrust faulting on either side of the QCF extending through the crust (Hyndman and Ellis, 1981;Rohr et al, 2000). This model requires at least 80 km of crustal shortening (assuming a 4 my duration of 20 mm=yr convergence) over a width of 30-60 km within both the Pacific and North American plates (Crouch et al, 1984;Rohr et al, 2000), which is similar to the 14-72 km of transpression taken up along the San Andreas fault (Crouch et al, 1984). In this latter case, the Queen Charlotte Trough could be explained by plate flexure due primarily to sediment loading on the Pacific plate (Prims et al, 1997) and does not require an additional load from the Pacific plate underthrusting the North American plate east of the QCF (Harris and Chapman, 1994).…”

Section: Queen Charlotte Fault Geometry and Convergencementioning

confidence: 99%

“…Processing was completed by M. Scheidhauer (Scheidhauer, 1997;Scheidhauer et al, 1999). This survey was important for interpretation of faults and basement structure in the area, and examples of the EW9412 profiles can be seen in Rohr et al (2000) and Tréhu et al (2015).…”

Section: Datamentioning

confidence: 99%

“…The fault is obliquely convergent along strike, with maximum convergence south of a bend in the QCF at 53.2°N. The northern QCF strikes at 338° (Rohr et al, 2000) and offshore of southeastern Alaska becomes the Fairweather fault, resulting in a 1200 km long onshore/offshore right-lateral transform zone (Fig. 1;Fletcher and Freymueller, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…South of 53.2°N, near Haida Gwaii, the strike of the QCF is 328°, ∼10°less than the northern QCF, creating oblique convergence between the plates and a structural regime similar to a restraining bend along the southern QCF ( Fig. 1; Rohr et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

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Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Walton

Gulick

Haeussler

et al. 2015

Bulletin of the Seismological Society of America

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The Queen Charlotte fault (QCF) is a dextral transform system located offshore of southeastern Alaska and western Canada, accommodating ∼4:4 cm=yr of relative motion between the Pacific and North American plates. Oblique convergence along the fault increases southward, and how this convergence is accommodated is still debated. Using seismic reflection data, we interpret offshore basement structure, faulting, and stratigraphy to provide a geological context for two recent earthquakes, an M w 7.5 strike-slip event near Craig, Alaska, and an M w 7.8 thrust event near Haida Gwaii, Canada. We map downwarped Pacific oceanic crust near 54°N, between the two rupture zones. Observed downwarping decreases north and south of 54°N, parallel to the strike of the QCF. Bending of the Pacific plate here may have initiated with increased convergence rates due to a plate motion change at ∼6 Ma. Tectonic reconstruction implies convergence-driven Pacific plate flexure, beginning at 6 Ma south of a 10°bend the QCF (which is currently at 53.2°N) and lasting until the plate translated past the bend by ∼2 Ma. Normal-faulted approximately late Miocene sediment above the deep flexural depression at 54°N, topped by relatively undeformed Pleistocene and younger sediment, supports this model. Aftershocks of the Haida Gwaii event indicate a normal-faulting stress regime, suggesting present-day plate flexure and underthrusting, which is also consistent with reconstruction of past conditions. We thus favor a Pacific plate underthrusting model to initiate flexure and accommodation space for sediment loading. In addition, mapped structures indicate two possible fault segment boundaries along the QCF at 53.2°N and at 56°N.

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Section: Queen Charlotte Fault Geometry and Convergencementioning

confidence: 99%

Section: Queen Charlotte Fault Geometry and Convergencementioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Walton

Gulick

Haeussler

et al. 2015

Bulletin of the Seismological Society of America

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2012 Haida Gwaii Quake: Insight Into Cascadia's Subduction Extent

Szeliga

2013

EoS Transactions

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The limits of Cascadia were first defined to contain nearly the entire margin of the Pacific Northwest, from Cape Mendocino through the Alaska Panhandle [Schuchert, 1910; Schuchert and Barrell, 1914]. Since that time, the boundary of Cascadia has shrunk to become essentially synonymous with the region where the Juan de Fuca plate subducts beneath the North American plate. As a consequence, seismic hazard assessments in the Pacific Northwest have conventionally focused on the potential for large megathrust earthquakes along the interface of the Juan de Fuca and North American plates.

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Slip Behavior of the Queen Charlotte Plate Boundary Before and After the 2012, M_W 7.8 Haida Gwaii Earthquake: Evidence From Repeating Earthquakes

Hayward

Bostock

2017

JGR Solid Earth

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The Queen Charlotte plate boundary, near Haida Gwaii, B.C., includes the dextral, strike‐slip, Queen Charlotte Fault (QCF) and the subduction interface between the downgoing Pacific and overriding North American plates. In this study, we present a comprehensive repeating earthquake catalog that represents an effective slip meter for both structures. The catalog comprises 712 individual earthquakes (0.3≤MW≤3.5) arranged into 224 repeating earthquake families on the basis of waveform similarity and source separation estimates from coda wave interferometry. We employ and extend existing relationships for repeating earthquake magnitudes and slips to provide cumulative slip histories for the QCF and subduction interface in six adjacent zones within the study area between 52.3°N and 53.8°N. We find evidence for creep on both faults; however, creep rates are significantly less than plate motion rates, which suggests partial locking of both faults. The QCF exhibits the highest degrees of locking south of 52.8°N, which indicates that the seismic hazard for a major strike‐slip earthquake is highest in the southern part of the study area. The 28 October 2012, MW 7.8 Haida Gwaii thrust earthquake occurred in our study area and altered the slip dynamics of the plate boundary. The QCF is observed to undergo accelerated, right‐lateral slip for 1–2 months following the earthquake. The subduction interface exhibits afterslip thrust motion that persists for the duration of the study period (i.e., 3 years and 2 months after the Haida Gwaii earthquake). Afterslip is greatest (5.7–8.4 cm/yr) on the periphery of the main rupture zone of the Haida Gwaii event.

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Transpression between two warm mafic plates: The Queen Charlotte Fault revisited

Cited by 61 publications

References 65 publications

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

2012 Haida Gwaii Quake: Insight Into Cascadia's Subduction Extent

Slip Behavior of the Queen Charlotte Plate Boundary Before and After the 2012, M_W 7.8 Haida Gwaii Earthquake: Evidence From Repeating Earthquakes

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Transpression between two warm mafic plates: The Queen Charlotte Fault revisited

Cited by 61 publications

References 65 publications

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

2012 Haida Gwaii Quake: Insight Into Cascadia's Subduction Extent

Slip Behavior of the Queen Charlotte Plate Boundary Before and After the 2012, MW 7.8 Haida Gwaii Earthquake: Evidence From Repeating Earthquakes

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Product

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Slip Behavior of the Queen Charlotte Plate Boundary Before and After the 2012, M_W 7.8 Haida Gwaii Earthquake: Evidence From Repeating Earthquakes