Future Cascadia megathrust rupture delineated by episodic tremor and slip

A suite of 15 episodic tremor and slip events imaged between 1997 and 2008 along the northern Cascadia subduction zone suggests future coseismic rupture will extend to 25 km depth, or ∼60 km inland of the Pacific coast, rather than stopping offshore at 15 km depth. An ETS‐derived coupling profile ac...

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Bibliographic Details
Published in:Geophysical research letters 2009-11, Vol.36 (22), p.n/a
Main Authors: Chapman, James S., Melbourne, Timothy I.
Format: Article
Language:English
Subjects:
Earth sciences
Earth, ocean, space
earthquake
Earthquakes
ETS
Exact sciences and technology
Global Positioning System
Global positioning systems
GPS
Joining
Marine
Mathematical models
Rupture
Satellite navigation systems
Seismic activity
Seismic phenomena
Seismology
Slip
subduction
Tremors
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Summary:A suite of 15 episodic tremor and slip events imaged between 1997 and 2008 along the northern Cascadia subduction zone suggests future coseismic rupture will extend to 25 km depth, or ∼60 km inland of the Pacific coast, rather than stopping offshore at 15 km depth. An ETS‐derived coupling profile accurately predicts GPS‐measured interseismic deformation of the overlying North American plate, as measured by ∼50 continuous GPS stations across western Washington State. When extrapolated over the 550‐year average recurrence interval of Cascadia megathrust events, the coupling model also replicates the pattern and amplitude of coseismic coastal subsidence inferred from previous megathrust earthquakes here. For only the Washington State segment of the Cascadia margin, this translates into an Mw = 8.9 earthquake, with significant moment release close to its metropolitan centers.
ISSN:0094-8276
1944-8007
DOI:10.1029/2009GL040465