scholarly journals Shallow Mantle Anisotropy Beneath the Juan de Fuca Plate

2017 ◽  
Vol 44 (22) ◽  
pp. 11,382-11,389 ◽  
Author(s):  
Brandon P. VanderBeek ◽  
Douglas R. Toomey
Keyword(s):  
Juan De Fuca Plate ◽  
Juan De Fuca ◽  
Mantle Anisotropy

The northern limit of the subducted Juan de Fuca Plate system

1998 ◽  
Vol 103 (B11) ◽  
pp. 26949-26961 ◽  
Author(s):  
John F. Cassidy ◽  
Robert M. Ellis ◽  
Costas Karavas ◽  
Garry C. Rogers
Keyword(s):  
Northern Limit ◽  
Juan De Fuca Plate ◽  
Juan De Fuca ◽  
Plate System

scholarly journals Amphibious surface-wave phase-velocity measurements of the Cascadia subduction zone

2019 ◽  
Vol 217 (3) ◽  
pp. 1929-1948 ◽  
Author(s):  
Helen A Janiszewski ◽  
James B Gaherty ◽  
Geoffrey A Abers ◽  
Haiying Gao ◽  
Zachary C Eilon
Keyword(s):  
Phase Velocity ◽  
Subduction Zone ◽  
Upper Mantle ◽  
Seismic Data ◽  
Cascadia Subduction Zone ◽  
Crust And Upper Mantle ◽  
Juan De Fuca Plate ◽  
Wave Phase Velocity ◽  
Juan De Fuca ◽  
S Period

SUMMARY A new amphibious seismic data set from the Cascadia subduction zone is used to characterize the lithosphere structure from the Juan de Fuca ridge to the Cascades backarc. These seismic data are allowing the imaging of an entire tectonic plate from its creation at the ridge through the onset of the subduction to beyond the volcanic arc, along the entire strike of the Cascadia subduction zone. We develop a tilt and compliance correction procedure for ocean-bottom seismometers that employs automated quality control to calculate robust station noise properties. To elucidate crust and upper-mantle structure, we present shoreline-crossing Rayleigh-wave phase-velocity maps for the Cascadia subduction zone, calculated from earthquake data from 20 to 160 s period and from ambient-noise correlations from 9 to 20 s period. We interpret the phase-velocity maps in terms of the tectonics associated with the Juan de Fuca plate history and the Cascadia subduction system. We find that thermal oceanic plate cooling models cannot explain velocity anomalies observed beneath the Juan de Fuca plate. Instead, they may be explained by a ≤1 per cent partial melt region beneath the ridge and are spatially collocated with patches of hydration and increased faulting in the crust and upper mantle near the deformation front. In the forearc, slow velocities appear to be more prevalent in areas that experienced high slip in past Cascadia megathrust earthquakes and generally occur updip of the highest-density tremor regions and locations of intraplate earthquakes. Beneath the volcanic arc, the slowest phase velocities correlate with regions of highest magma production volume.

The Juan de Fuca Plate: A Sticky Situation

Science News ◽  
1987 ◽  
Vol 132 (3) ◽  
pp. 42
Author(s):  
Richard Monastersky
Keyword(s):  
Juan De Fuca Plate ◽  
Juan De Fuca

Structural variation along the Devil's Mountain fault zone, northwestern Washington

2006 ◽  
Vol 43 (4) ◽  
pp. 433-446 ◽  
Author(s):  
Nathan Hayward ◽  
Mladen R Nedimović ◽  
Matthew Cleary ◽  
Andrew J Calvert
Keyword(s):  
Fault Zone ◽  
Structural Variation ◽  
Puget Sound ◽  
Seismic Reflection Data ◽  
Juan De Fuca Plate ◽  
The North ◽  
Reflection Data ◽  
Juan De Fuca ◽  
Main Fault ◽  
Juan De Fuca Strait

The eastern Juan de Fuca Strait is subject to long-term, north–south-oriented shortening. The observed deformation is interpreted to result from the northward motion of the Oregon block, which is being driven north by oblique subduction of the oceanic Juan de Fuca plate. Seismic data, acquired during the Seismic Hazards Investigation in Puget Sound survey are used, with coincident first-arrival tomographic velocities, to interpret structural variation along the Devil's Mountain fault zone in the eastern Juan de Fuca Strait. The Primary fault of the Devil's Mountain fault zone developed at the northern boundary of the Everett basin, during north–south-oriented Tertiary compression. Interpretation of seismic reflection data suggests that, based on their similar geometry including the large magnitude of pre-Tertiary basement offset, the Primary fault of the Devil's Mountain fault west of ~122.95°W and the Utsalady Point fault represent the main fault of the Tertiary Devil's Mountain fault zone. The Tertiary Primary fault west of ~122.95°W was probably kinematically linked to faults to the east (Utsalady Point, Devil's Mountain, and another to the south), by an oblique north–northeast-trending transfer zone or ramp. Left-lateral transpression controlled the Quaternary evolution of the Devil's Mountain fault zone. Quaternary Primary fault offsets are smaller to the east of ~122.95°W, suggesting that stress here was in part accommodated by the prevalent oblique compressional structures to the north. Holocene deformation has focussed on the Devil's Mountain, Utsalady Point, and Strawberry Point faults to the east of ~122.8° but has not affected the Utsalady Point fault to the west of ~122.8°W.

Seismic anisotropy beneath the Juan de Fuca plate system: Evidence for heterogeneous mantle flow

Geology ◽  
2015 ◽  
pp. G37181.1 ◽  
Author(s):  
Miles Bodmer ◽  
Douglas R. Toomey ◽  
Emilie E. Hooft ◽  
John Nábĕlek ◽  
Jochen Braunmiller
Keyword(s):  
Seismic Anisotropy ◽  
Mantle Flow ◽  
Juan De Fuca Plate ◽  
Juan De Fuca ◽  
Heterogeneous Mantle ◽  
Plate System
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