Hawthorne, JC orcid.org/0000-0002-4117-2082, Bostock, MG, Royer, AA et al. (1 more author) (2016) Variations in slow slip moment rate associated with rapid tremor reversals in Cascadia. Geochemistry, Geophysics, Geosystems, 17 (12). pp. 4899-4919. ISSN 1525-2027
Abstract
During large slow slip events, tremor sometimes propagates in the reverse along-strike direction for a few hours, at speeds 10 to 40 times faster than the forward propagation. We examine the aseismic slip that underlies this rapidly propagating tremor. We use PBO (Plate Boundary Observatory) borehole strainmeter data to search for variations in the slow slip moment rate during 35 rapid tremor reversals (RTRs) that occurred beneath Vancouver Island. The strain records reveal that, on average, the strain rate increases by about 100% ( math formula) during RTRs. Given the Green's functions expected for slip in the RTR locations, these strain rate increases imply 50 to 130% increases in the aseismic moment rate. The median moment released per RTR is between 8 and 21% of the daily slow slip moment, equivalent to that of a MW 5.0 to 5.1 earthquake. By combining the RTR moments with the spatial extents suggested by tremor, we estimate that a typical RTR has peak slip of roughly one-sixth of the peak slip in the main slow slip event, near-front slip rate of a few to ten times the main front slip rate, stress drop around half the main event stress drop, and strain energy release rate around one-tenth that of the main front. Our observations support a picture of RTRs as aseismic subevents with high slip rates but modest strain energy release. RTRs appear to contribute to but not dominate the overall slow slip moment, though they may accommodate most of the slip in certain locations.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016. American Geophysical Union. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | slow slip; tremor; borehole strain |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 Jan 2017 15:25 |
Last Modified: | 22 Jun 2017 00:38 |
Published Version: | https://doi.org/10.1002/2016GC006489 |
Status: | Published |
Publisher: | American Geophysical Union |
Identification Number: | 10.1002/2016GC006489 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:110184 |