Rollins, J orcid.org/0000-0002-5291-6956 and Stein, RS (2010) Coulomb stress interactions among M ≥ 5.9 earthquakes in the Gorda deformation zone and on the Mendocino Fault Zone, Cascadia subduction zone, and northern San Andreas Fault. Journal of Geophysical Research: Solid Earth, 115 (B12). B12306. ISSN 2169-9356
Abstract
[1] The Gorda deformation zone, a 50,000 km2 area of diffuse shear and rotation offshore northernmost California, has been the site of 20 M ≥ 5.9 earthquakes on four different fault orientations since 1976, including four M ≥ 7 shocks. This is the highest rate of large earthquakes in the contiguous United States. We calculate that the source faults of six recent M ≥ 5.9 earthquakes had experienced ≥0.6 bar Coulomb stress increases imparted by earthquakes that struck less than 9 months beforehand. Control tests indicate that ≥0.6 bar Coulomb stress interactions between M ≥ 5.9 earthquakes separated by <9 months are unlikely to occur by random chance, suggesting that the multiple short‐term stress interactions observed among the recent Gorda zone earthquakes are not an apparent effect. In all well‐constrained ≥0.2 bar Coulomb stress interactions between earthquakes that occurred within 4 years of each other, the second earthquake is promoted. On longer timescales, calculated stress changes imparted by the 1980 Mw = 7.3 Trinidad earthquake are consistent with the locations of M ≥ 5.9 earthquakes in the Gorda zone until at least 1995, as well as earthquakes on the Mendocino Fault Zone in 1994 and 2000. Coulomb stress changes imparted by the 1980 earthquake are also consistent with its distinct elbow‐shaped aftershock pattern. From these observations, we derive generalized static stress interactions among right‐lateral, left‐lateral and thrust faults near triple junctions.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2010 by the American Geophysical Union. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | Coulomb stress; earthquake interaction; Gorda deformation zone |
Dates: |
|
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: | 24 Feb 2020 14:31 |
Last Modified: | 24 Feb 2020 14:31 |
Status: | Published |
Publisher: | American Geophysical Union |
Identification Number: | 10.1029/2009JB007117 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:155123 |