Published In
Geology
Document Type
Article
Publication Date
6-2017
Subjects
Fault systems -- Oregon, Fault lines (Geology)
Abstract
Deep, episodic slow slip on the Cascadia subduction megathrust of western North America is accompanied by low-frequency tremor in a zone of high fluid pressure between 30 and 40 km depth. Tremor density (tremor epicenters per square kilometer) varies along strike, and lower tremor density statistically correlates with upper plate faults that accommodate northward motion and rotation of forearc blocks. Upper plate earthquakes occur to 35 km depth beneath the faults. We suggest that the faults extend to the overpressured megathrust, where they provide fracture pathways for fluid escape into the upper plate. This locally reduces megathrust fluid pressure and tremor occurrence beneath the faults. Damping of tremor and related slow slip caused by fluid escape could affect fault properties of the megathrust, possibly influencing the behavior of great earthquakes.
Rights
Copyright (c) 2017 The Authors
This work is licensed under a Creative Commons Attribution 4.0 International License.
Locate the Document
DOI
10.1130/G38835.1
Persistent Identifier
https://archives.pdx.edu/ds/psu/41123
Citation Details
Wells, R. E., Blakely, R. J., Wech, A. G., McCrory, P. A., & Michael, A. (2017). Cascadia subduction tremor muted by crustal faults. Geology, 45(6), 515-518.