@article {RN122,
	title = {A Joint Inversion for Three-dimensional P and S Wave Velocity Structure and Earthquake Locations Beneath Axial Seamount},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {n/a},
	number = {n/a},
	year = {2019},
	type = {Journal Article},
	abstract = {Axial Seamount is a prominent volcano located at the intersection of the Juan de Fuca Ridge and the Cobb-Eickelberg hot spot in the northeast Pacific Ocean that has erupted in 1998, 2011, and 2015. The 2015 eruption was recorded by a seven-station seismic network in the southern part of the summit caldera that forms part of the Ocean Observatories Initiative Cabled Array. We utilize a data set of ~3,900 well-recorded earthquakes from January 2015 to February 2017 and a three-dimensional P wave velocity model obtained previously from active source data to conduct a joint inversion for three-dimensional P and S wave velocities and hypocentral parameters. The resulting velocity models are used to relocate >76,000 earthquakes with >=10 arrival times. The velocity models reveal a low-velocity anomaly in the center of the southern caldera at depths less than ~2 km, which corresponds to the top of the magma chamber and is interpreted as a region that is intensely fractured by the cyclical deformation of the caldera. High velocities around the caldera rim are likely due to consolidated undeformed lava flows. Low VP/VS in the southern caldera is consistent with the presence of hydrothermal vapor. Low S wave velocities and high VP/VS in the northern caldera may indicate a region dominated by thin cracks caused by dike injection. The relocated earthquakes delineate outward-dipping ring faults more clearly than previous studies and image a subvertical inward-dipping fault within the network that connects to the east caldera wall and eruptive fissures.},
	keywords = {axial seamount, Earthquakes location, Hydrothermal systems, Joint inversion, Tomography, volcano},
	issn = {2169-9313},
	doi = {10.1029/2019JB017970},
	author = {Baillard, Christian and Wilcock, William S. D. and Arnulf, Adrien F. and Tolstoy, Maya and Waldhauser, Felix}
}
