Cascadia low frequency earthquakes at the base of an overpressured subduction shear zone

Andrew J. Calvert (), Michael G. Bostock, Geneviève Savard and Martyn J. Unsworth
Additional contact information
Andrew J. Calvert: Simon Fraser University
Michael G. Bostock: Ocean and Atmospheric Sciences, 2207 Main Mall, University of British Columbia
Geneviève Savard: University of Calgary
Martyn J. Unsworth: University of Alberta

Nature Communications, 2020, vol. 11, issue 1, 1-10

Abstract: Abstract In subduction zones, landward dipping regions of low shear wave velocity and elevated Poisson’s ratio, which can extend to at least 120 km depth, are interpreted to be all or part of the subducting igneous oceanic crust. This crust is considered to be overpressured, because fluids within it are trapped beneath an impermeable seal along the overlying inter-plate boundary. Here we show that during slow slip on the plate boundary beneath southern Vancouver Island, low frequency earthquakes occur immediately below both the landward dipping region of high Poisson’s ratio and a 6–10 km thick shear zone revealed by seismic reflections. The plate boundary here either corresponds to the low frequency earthquakes or to the anomalous elastic properties in the lower 3–5 km of the shear zone immediately above them. This zone of high Poisson’s ratio, which approximately coincides with an electrically conductive layer, can be explained by slab-derived fluids trapped at near-lithostatic pore pressures.

Date: 2020
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/s41467-020-17609-3 Abstract (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:natcom:v:11:y:2020:i:1:d:10.1038_s41467-020-17609-3

Ordering information: This journal article can be ordered from
https://www.nature.com/ncomms/

DOI: 10.1038/s41467-020-17609-3

Access Statistics for this article

Nature Communications is currently edited by Nathalie Le Bot, Enda Bergin and Fiona Gillespie

More articles in Nature Communications from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().