@article {liu_-situ_2023,
	title = {In-Situ Vp/Vs Reveals Fault-Zone Material Variation at the Westernmost Gofar Transform Fault, East Pacific Rise},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {128},
	number = {3},
	year = {2023},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JB025310},
	month = {03/2023},
	pages = {e2022JB025310},
	abstract = {Ocean transform faults often generate characteristic earthquakes that repeatedly rupture the same fault patches. The westernmost Gofar transform fault quasi-periodically hosts \~{}M6 earthquakes every \~{}5 years, and microseismicity suggests that the fault is segmented into five distinct zones, including a rupture barrier zone that may have modulated the rupture of adjacent M6 earthquakes. However, the relationship between the systematic slip behavior of the Gofar fault and the fault material properties is still poorly known. Specifically, the role of pore fluids in regulating the slip of the Gofar fault is unclear. Here, we use differential travel times between nearby earthquakes to estimate the in-situ Vp/Vs of the fault-zone materials. We apply this technique to the dataset collected by an ocean-bottom-seismometer network deployed around the Gofar fault in 2008, which recorded abundant microearthquakes, and find a moderate Vp/Vs of 1.75{\textendash}1.80 in the rupture barrier zone and a low Vp/Vs of 1.61{\textendash}1.69 in the down-dip edge of the 2008 M6 rupture zone. This lateral variation in Vp/Vs may be caused by both pore fluids and chemical alteration. We also find a 5\%{\textendash}10\% increase in Vp/Vs in the barrier zone during the 9 months before the mainshock. This increase may have been caused by fluid migrations or slip transients in the barrier zone.},
	keywords = {fault-zone structure, ocean-bottom seismometer, oceanic transform fault, pore fluids, slip dilatancy, VP/VS ratio},
	issn = {2169-9356},
	doi = {10.1029/2022JB025310},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JB025310},
	author = {Liu, Tianze and Gong, Jianhua and Fan, Wenyuan and Lin, Guoqing}
}
@article {gong_machine_2023,
	title = {Machine Learning-Based New Earthquake Catalog Illuminates On-Fault and Off-Fault Seismicity Patterns at the Discovery Transform Fault, East Pacific Rise},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {24},
	number = {9},
	year = {2023},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2023GC011043},
	pages = {e2023GC011043},
	abstract = {Oceanic transform faults connect spreading centers and are imprinted with previous tectonic events. However, their tectonic interactions are not well understood due to limited observations. The Discovery transform fault system at 4{\textdegree}S, East Pacific Rise (EPR), represents a young transform system, offering a unique opportunity to study the interplay between faulting and other tectonic events at an early phases of an oceanic transform system. Discovery regularly hosts M5{\textendash}6 characteristic earthquakes, and the seafloor north of Discovery includes a 35 km-long rift zone that records a complex history of rifting, faulting and volcanism, suggesting that the transform faults likely interact with regional tectonic activity. We apply a machine-learning enabled workflow to locate 21,391 earthquakes recorded during a 1-year ocean bottom seismometer experiment in 2008. Our results indicate that seismicity on the western Discovery fault is separated into seven patches with distinct aseismic and seismic slip modes. Additionally, we observe a patch of off-fault seismicity near where seafloor abyssal hills intersect the rift zone. This seismicity may have been caused by varying opening rates as spreading rate decreases from north to south in the rift zone. Our findings suggest that the Discovery system is still evolving, and that system equilibrium has not been reached between rifting and faulting. These results reflect the complex yet rarely observed interactions between fault slip, plate rotation, and rifting which are likely ubiquitous at oceanic transform systems.},
	keywords = {fault segmentation, microseismicity, oceanic transform fault, rifting},
	issn = {1525-2027},
	doi = {10.1029/2023GC011043},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023GC011043},
	author = {Gong, Jianhua and Fan, Wenyuan and Parnell-Turner, Ross}
}
@article {mcguire_millimeter-level_2013,
	title = {Millimeter-level precision in a seafloor geodesy experiment at the Discovery transform fault, East Pacific Rise},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {14},
	number = {10},
	year = {2013},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ggge.20225},
	pages = {4392{\textendash}4402},
	abstract = {Direct-path acoustic ranging is a promising seafloor geodetic technique for continuous high-resolution monitoring of geodynamical process such as fault slip and magma intrusion. Here we report on a yearlong acoustic ranging experiment conducted across the discovery transform fault at \~{}4{\textdegree}S on the East Pacific Rise. The ranging instruments utilized a novel acoustic signal designed to enhance precision. We find that, after correcting for variations in sound speed at the path end-points, the ranging measurements have a precision of \~{}1 mm over baselines approaching 1 km in length. The primary difficulty in this particular experiment was with the physical stability of the benchmarks, which were deployed free fall from a ship. Despite the stability issues, it appears that the portion of the transform fault that the array covered was locked during the year of our survey. The primary obstacle to continuous, high sample rate, high-precision geodetic monitoring of oceanic ridges and transform faults is now limited to the construction of geodetic monuments that are well anchored into bedrock.},
	keywords = {oceanic transform fault, seafloor geodesy},
	issn = {1525-2027},
	doi = {10.1002/ggge.20225},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ggge.20225},
	author = {McGuire, Jeffrey J. and Collins, John A.}
}
