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Guangyu Xu

Research Scientist/Engineer - Senior





Research Interests

Guangyu Xu's research combines underwater acoustic and numerical modeling techniques to study fluid flows within both the seafloor and the ocean. Xu's scientific questions focus on: dynamics associated with seafloor hydrothermal discharge and its dispersal near a mid-ocean ridge, deep ocean flows and their interconnections with surface processes, sub-seafloor hydrothermal circulation, and acoustic seafloor characterization.

Department Affiliation



B.S. Ocean Technology, Ocean University of China (Qingdao, Shandong Province, China), 2008

M.S. Marine Sciences, University of Georgia, 2010

Ph.D. Marine Sciences, Rutgers University, 2015


2000-present and while at APL-UW

Permeability and seismicity rate changes at an inflating submarine volcano caused by dynamic stresses

Barkat, A., Y.J. Tan, G. Xu, F. Waldhauser, M. Tolstoy, and W.S.D. Wilcock, "Permeability and seismicity rate changes at an inflating submarine volcano caused by dynamic stresses," Earth Planet. Sci. Lett., 632, doi:10.1016/j.epsl.2024.118625, 2024.

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15 Apr 2024

Transient stresses from the passage of seismic waves are known to trigger earthquakes and cause crustal permeability changes. However, whether permeability change is a main driver of dynamic earthquake triggering remains debated. Our understanding of the characteristics of dynamic triggering in submarine volcanic environments is also limited due to the lack of offshore observations. Here, we utilize a high-resolution micro-seismicity catalog from July 2015 to July 2022 to evaluate the triggering response of Axial Seamount, an inflating and seismically active submarine volcano located in the northeast Pacific Ocean. We report statistically significant episodes of dynamic earthquake triggering for ∼18 % of the teleseismic events investigated, which is comparable with subaerial tectonic and volcanic environments. We do not observe any obvious dependence of triggering rate on the amplitude of peak ground velocity. However, a comparison of the triggering rate and the cumulative magma volume shows that the triggering susceptibility might increase as the volcano becomes more critically stressed. Using data recorded by a temperature sensor in a black smoker, we compute the phase lag between hydrothermal vent-fluid temperature and tidal loading amplitude before and after the arrival of teleseismic waves to probe the relationship between permeability change and dynamic triggering. While the energy density thresholds for dynamic earthquake triggering and permeability change are comparable, both triggering and non-triggering observations show similar proportions of permeability changes. Our results suggest that permeability change induced by transient stresses might not be a necessary or primary mechanism that drives dynamic earthquake triggering.

Subsurface acoustic ducts in the Northern California current system

Xu, G., R.R. Harcourt, D. Tang, B.T. Hefner, E.I. Thorsos, and J.B. Mickett, "Subsurface acoustic ducts in the Northern California current system," J. Acoust. Soc. Am., 155, 1881-1894, doi:10.1121/10.0024146, 2024.

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7 Mar 2024

This study investigates the subsurface sound channel or acoustic duct that appears seasonally along the U.S. Pacific Northwest coast below the surface mixed layer. The duct has a significant impact on sound propagation at mid-frequencies by trapping sound energy and reducing transmission loss within the channel. A survey of the sound-speed profiles obtained from archived mooring and glider observations reveals that the duct is more prevalent in summer to fall than in winter to spring and offshore of the shelf break than over the shelf. The occurrence of the subsurface duct is typically associated with the presence of a strong halocline and a reduced thermocline or temperature inversion. Furthermore, the duct observed over the shelf slope corresponds to a vertically sheared along-slope velocity profile, characterized by equatorward near-surface flow overlaying poleward subsurface flow. Two potential duct formation mechanisms are examined in this study, which are seasonal surface heat exchange and baroclinic advection of distinct water masses. The former mechanism regulates the formation of a downward-refracting sound-speed gradient that caps the duct near the sea surface, while the latter contributes to the formation of an upward-refracting sound-speed gradient that defines the duct's lower boundary.

Dispersion of deep-sea hydrothermal plumes at the Endeavour Segment of the Juan de Fuca Ridge: a multiscale numerical study

Xu, G., C.R. German, "Dispersion of deep-sea hydrothermal plumes at the Endeavour Segment of the Juan de Fuca Ridge: a multiscale numerical study," Front. Mar. Sci., 10, doi:10.3389/fmars.2023.1213470, 2023.

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20 Jul 2023

A multiscale numerical framework has been developed to investigate the dispersion of deep-sea hydrothermal plumes that originate from the Endeavour Segment of the Juan de Fuca Ridge located in the Northeast Pacific. The analysis of simulation outputs presented in this study provides insights into the influences of tidal forcing and the buoyancy flux associated with hydrothermal venting on ocean circulation and plume dispersion in the presence of pronounced seafloor topography. The results indicate that tidal forcing drives anti-cyclonic circulation near the ridge-axis, while hydrothermal venting induces cyclonic circulation around vent fields within the axial rift valley. Tidal forcing has a notable impact on plume dispersion, particularly near the large topographic features to the north of the Endeavour Segment. Furthermore, plume dispersion exhibits notable inter-annual variability, with a northbound trajectory in 2016 and a southbound trajectory in 2021. The study also reveals that both buoyancy fluxes and tidal forcing enhance the mixing of hydrothermal plumes with ambient seawater.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center