A Lack of Dynamic Triggering of Slow Slip and Tremor Indicates That the Shallow Cascadia Megathrust Offshore Vancouver Island Is Likely Locked

Jeffrey J. McGuire, John A. Collins, Earl Davis, Keir Becker, Martin Heesemann

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Great subduction zone earthquakes vary considerably in the updip extent of megathrust rupture. It is unclear if this diversity reflects variations in interseismic strain accumulation owing to the limited number of subduction zones with seafloor monitoring. We use a borehole seismic-geodetic observatory installed at the updip end of the Cascadia fault offshore Vancouver Island to show that the megathrust there does not appear to slip in triggered tremor or slow-slip events when subjected to moderate dynamic stress transients. Borehole tilt and seismic data from recent teleseismic M7.6–8.1 earthquakes demonstrate a lack of triggered slow slip above the Mw 4.0 level and an absence of triggered tremor despite shear-stress transients of 1–10 kPa that were sufficient to trigger tremor on the downdip end of the interface. Our observations are most consistent with a model in which the Cascadia fault offshore Vancouver Island is locked all the way to the trench.

Original languageEnglish (US)
Pages (from-to)11,095-11,103
JournalGeophysical Research Letters
Volume45
Issue number20
DOIs
StatePublished - Oct 28 2018

Keywords

  • Cascadia subduction zone
  • seafloor geodesy
  • seismic tremor

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

Fingerprint Dive into the research topics of 'A Lack of Dynamic Triggering of Slow Slip and Tremor Indicates That the Shallow Cascadia Megathrust Offshore Vancouver Island Is Likely Locked'. Together they form a unique fingerprint.

Cite this