Along-trench structural variations of the subducting Juan de Fuca Plate from multichannel seismic reflection imaging
Carbotte, Suzanne M.
Canales, J. Pablo
Nedimovic, Mladen R.
MetadataShow full item record
KeywordCascadia subduction zone; Juan de Fuca Plate; Multichannel seismic reflection imaging; Subduction bending faulting; Propagator wakes; Strike-slip faults
To characterize the along‐strike structural variations of the Juan de Fuca (JdF) Plate as it enters the Cascadia subduction zone, we present prestack time migrated multichannel seismic reflection images of the JdF Plate along a 400‐km‐long trench‐parallel transect extending from 44.3°N to 47.8°N. Beneath the 1.8–3.0‐km‐thick sediment cover, our data reveal basement topographic anomalies associated with a 1.2‐km‐high seamount and in the vicinity of propagator wakes (390–540‐m relief). Weak Moho reflections are imaged beneath the propagator wakes and coincide with reduced Vp in the lower crust and/or uppermost mantle. The inferred locations of propagator wakes in the downgoing plate collocate with some of the boundaries of episodic tremor and slip events. We propose that the structural and hydration heterogeneities associated with these features could lead to anomalous plate interface properties and contribute to episodic tremor and slip segmentation. Intracrustal reflections with apparent dips (20°–30°) consistent with subduction bending normal faults change near 45.8°N, from northward dipping reflections confined to the middle crust in the north to antithetic reflections through the crust in the south, coinciding with a Vp reduction in the lower crust. These observations indicate more extensive faulting deformation and associated hydration of the JdF Plate south of 45.8°N, which likely results from variations of slab dip and resistance to subduction across 46°N. Basement offsets and abrupt depth/amplitude changes in Moho reflections are imaged beneath the four major WNW trending strike‐slip faults that cross the Cascadia deformation front, providing strong evidence of a lower plate origin for these faults.
Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 123 (2018): 3122-3146, doi:10.1002/2017JB015059.
Suggested CitationArticle: Han, Shuoshuo, Carbotte, Suzanne M., Canales, J. Pablo, Nedimovic, Mladen R., Carton, Helene, "Along-trench structural variations of the subducting Juan de Fuca Plate from multichannel seismic reflection imaging", Journal of Geophysical Research: Solid Earth 123 (2018): 3122-3146, DOI:10.1002/2017JB015059, https://hdl.handle.net/1912/10430
Showing items related by title, author, creator and subject.
Seismic reflection imaging of the Juan de Fuca plate from ridge to trench : new constraints on the distribution of faulting and evolution of the crust prior to subduction Han, Shuoshuo; Carbotte, Suzanne M.; Canales, J. Pablo; Nedimovic, Mladen R.; Carton, Helene; Gibson, James C.; Horning, Gregory W. (John Wiley & Sons, 2016-03-21)We present prestack time-migrated multichannel seismic images along two cross-plate transects from the Juan de Fuca (JdF) Ridge to the Cascadia deformation front (DF) offshore Oregon and Washington from which we characterize ...
Van Avendonk, Harm J. A.; Holbrook, W. Steven; Lizarralde, Daniel; Denyer, P. (American Geophysical Union, 2011-06-22)The Cocos plate experiences extensional faulting as it bends into the Middle American Trench (MAT) west of Nicaragua, which may lead to hydration of the subducting mantle. To estimate the along strike variations of volatile ...
Subsea ice-bearing permafrost on the U.S. Beaufort Margin : 1. Minimum seaward extent defined from multichannel seismic reflection data Brothers, Laura L.; Herman, Bruce M.; Hart, Patrick E.; Ruppel, Carolyn D. (John Wiley & Sons, 2016-11-04)Subsea ice-bearing permafrost (IBPF) and associated gas hydrate in the Arctic have been subject to a warming climate and saline intrusion since the last transgression at the end of the Pleistocene. The consequent degradation ...