Variations in earthquake rupture properties along the Gofar transform fault, East Pacific Rise

Crust and Lithospheric Structure - Seismic Structure of Mid-Ocean Ridges

“…Only a few seismic studies have examined their structure (e.g., McGuire et al, 2012;Roland et al, 2012;van Avendonk et al, 1998van Avendonk et al, , 2001, and these studies are mainly limited to imaging at crustal depths. Transform faults are long-lasting features that can offset ridges by one hundred or more kilometers, though usually less, and leave large fracture zones in their wakes.…”

Tectonic Tremor Recorded by Ocean Bottom Seismometers

“…These tasks are particularly challenging in offshore environments where the investigation of plate boundary processes, especially within subduction-zone megathrusts, typically relies, at least in part, on ocean bottom seismometers (OBSs). OBS deployments are increasingly common and have improved our ability to detect offshore earthquake swarms (e.g., McGuire et al, 2012), but their utility for detecting or locating seismic tremor associated with slow slip has not been investigated in detail. Here we demonstrate that seismic tremor associated with the deep extension of the Alpine fault has been recorded on an OBS network lying off the west coast of New Zealand's South Island (Stachnik et al, 2012;Yang et al, 2012).…”

Seismic velocity constraints on the material properties that control earthquake behavior at the Quebrada‐Discovery‐Gofar transform faults, East Pacific Rise

“…Recently, the observation that large East Pacific Rise (EPR) and Juan de Fuca Ridge transform earthquakes occur quasiperiodically on overlapping fault patches has provided evidence that seismogenic segments of oceanic transform faults are separated by stationary, velocity‐strengthening rupture barriers [ McGuire , 2008; Boettcher and McGuire , 2009]. Based on centroid locations from surface waves of large RTF earthquakes throughout the past ∼20 years, it appears that discrete fault segments consistently do not permit propagation of large main shock ruptures, and instead release stress through aseismic creep transients, swarms of smaller seismic events or a combination of the two [ Roland and McGuire , 2009; McGuire et al , 2012]. Together, low seismic coupling and earthquake rupture patterns at oceanic transforms signify strong spatial variations in fault frictional properties [ Boatwright and Cocco , 1996; Marone , 1998; Kaneko et al , 2010] that are likely influenced by fault structure and/or material variability, rather than temperature alone.…”