The relationship between seismicity and fault structure on the Discovery transform fault, East Pacific Rise
Boettcher, Margaret S.
McGuire, Jeffrey J.
Collins, John A.
MetadataShow full item record
There is a global seismic moment deficit on mid-ocean ridge transform faults, and the largest earthquakes on these faults do not rupture the full fault area. We explore the influence of physical fault structure, including step-overs in the fault trace, on the seismic behavior of the Discovery transform fault, 4S on the East Pacific Rise. One year of microseismicity recorded during a 2008 ocean bottom seismograph deployment (24,377 0 inline image ML inline image 4.6 earthquakes) and 24 years of Mw inline image 5.4 earthquakes obtained from the Global Centroid Moment Tensor catalog, are correlated with surface fault structure delineated from high-resolution multibeam bathymetry. Each of the 15 5.4 inline image Mw inline image 6.0 earthquakes that occurred on Discovery between 1 January 1990 and 1 April 2014 was relocated into one of five distinct rupture patches using a teleseismic surface wave cross-correlation technique. Microseismicity was relocated using the HypoDD relocation algorithm. The western fault segment of Discovery (DW) is composed of three zones of varying structure and seismic behavior: a zone with no large events and abundant microseismicity, a fully coupled zone with large earthquakes, and a complex zone with multiple fault strands and abundant seismicity. In general, microseismicity is reduced within the patches defined by the large, repeating earthquakes. While the extent of the large rupture patches on DW correlates with physical features in the bathymetry, step-overs in the primary fault trace are not observed at patch boundaries, suggesting along-strike heterogeneity in fault zone properties controls the size and location of the large events.
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 15 (2014): 3698–3712, doi:10.1002/2014GC005445.
Suggested CitationArticle: Wolfson-Schwehr, Monica, Boettcher, Margaret S., McGuire, Jeffrey J., Collins, John A., "The relationship between seismicity and fault structure on the Discovery transform fault, East Pacific Rise", Geochemistry, Geophysics, Geosystems 15 (2014): 3698–3712, DOI:10.1002/2014GC005445, https://hdl.handle.net/1912/6984
Showing items related by title, author, creator and subject.
Behn, Mark D.; Boettcher, Margaret S.; Hirth, Greg (Geological Society of America, 2007-04)We use three-dimensional finite element simulations to investigate the temperature structure beneath oceanic transform faults. We show that using a rheology that incorporates brittle weakening of the lithosphere generates ...
Seismic velocity constraints on the material properties that control earthquake behavior at the Quebrada-Discovery-Gofar transform faults, East Pacific Rise Roland, Emily C.; Lizarralde, Daniel; McGuire, Jeffrey J.; Collins, John A. (American Geophysical Union, 2012-11-17)Mid-ocean ridge transform faults (RTFs) vary strongly along strike in their ability to generate large earthquakes. This general observation suggests that local variations in material properties along RTFs exert a primary ...
Imaging along-strike variations in mechanical properties of the Gofar transform fault, East Pacific Rise Froment, B.; McGuire, Jeffrey J.; van der Hilst, R. D.; Gouedard, P.; Roland, Emily C.; Zhang, H.; Collins, John A. (John Wiley & Sons, 2014-09-23)A large part of global plate motion on mid-ocean ridge transform faults (RTFs) is not accommodated as major earthquakes. When large earthquakes do occur, they often repeat quasiperiodically. We focus here on the high slip ...