@article {zheng_characterizing_2024,
	title = {Characterizing Sub-Seafloor Seismic Structure of the Alaska Peninsula Along the Alaska-Aleutian Subduction Zone},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {129},
	number = {11},
	year = {2024},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2024JB029862},
	pages = {e2024JB029862},
	abstract = {Abstract A shallow sub-seafloor seismic model that includes well-determined seismic velocities and clarifies sediment-crust discontinuities is needed to characterize the physical properties of marine sediments and the oceanic crust and to serve as a reference for deeper seismic modeling endeavors. This study estimates the seismic structure of marine sediments and the shallow oceanic crust of the Alaska-Aleutian subduction zone at the Alaska Peninsula, using data from the Alaska Amphibious Community Seismic Experiment (AACSE). We measure seafloor compliance and Ps converted wave delays from AACSE ocean-bottom seismometers (OBS) and seafloor pressure data and interpret these measurements using a joint Bayesian Monte Carlo inversion to produce a sub-seafloor S-wave velocity model beneath each available OBS station. The sediment thickness across the array varies considerably, ranging from about 50 m to 2.80 km, with the thickest sediment located in the continental slope. Lithological composition plays an important role in shaping the seismic properties of seafloor sediment. Deep-sea deposits on the incoming plate, which contain biogenic materials, tend to have reduced S-wave velocities, contrasting with the clay-rich sediments in the shallow continental shelf and continental slope. A difference in S-wave velocities is observed for upper oceanic crust formed at fast-rate (Shumagin) and intermediate-rate (Semidi) spreading centers. The reduced S-wave velocities in the Semidi crust may be caused by increased faulting and possible lithological variations, related to a previous period of intermediate-rate spreading.},
	keywords = {Alaska peninsula, seafloor compliance, sub-seafloor structure},
	doi = {https://doi.org/10.1029/2024JB029862},
	author = {Zheng, Mengjie and Sheehan, Anne F. and Liu, Chuanming and Wu, Mengyu and Ritzwoller, Michael H.}
}
@article {liu_seismic_2024,
	title = {Seismic Azimuthal Anisotropy Within the Juan de Fuca - Gorda Plate System},
	journal = {Geophysical Research Letters},
	volume = {51},
	number = {22},
	year = {2024},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2024GL111835},
	pages = {e2024GL111835},
	abstract = {Abstract We estimate seismic azimuthal anisotropy for the Juan de Fuca - Gorda plates from inversion of a new 10{\textendash}80 s period Rayleigh wave dataset, resulting in a two-layer model to 80 km depth. In the lithosphere, most anisotropy patterns reflect the kinematics of plate formation, as approximated from seafloor-age-based paleo-spreading, except for regions close to propagator wakes and near plate boundaries. In the asthenosphere, the fast propagation orientations align with convective shear as inferred from the NUVEL1A plate motion model, which is indicative of a \~{}3 Myr average, rather than with the more recent, \~{}0.8 Myr, motions inferred from MORVEL. Regional anisotropy of this young plate system thus records convection like older plates such as the Pacific. On smaller scales, anisotropy imaging provides insights into dynamics of plate generation and can further elucidate plate reorganizations and changes in boundary loading.},
	keywords = {juan de fuca plate, oceanic lithosphere, seismic aniostropy, seismic tomography, surface wave tomography},
	doi = {https://doi.org/10.1029/2024GL111835},
	author = {Liu, Chuanming and Becker, Thorsten and Wu, Mengyu and Han, Shuoshuo and Ritzwoller, Michael H.}
}
@article {wu_plate_2023,
	title = {Plate Age and Uppermost Mantle Structure Across the Juan de Fuca and Gorda Plates},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {128},
	number = {8},
	year = {2023},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2023JB026494},
	pages = {e2023JB026494},
	abstract = {To test the relationship between plate age and uppermost mantle structure for the Juan de Fuca and Gorda plates, as well as the mode of lithospheric cooling, we produce a new 3D oceanic shear wave speed (VS) model. This model is constructed using a new high-quality Rayleigh wave phase speed data set across the plates and is based on a novel thermo-seismic hybrid parameterization. In the lithosphere, we find that the VS structure is primarily (68\% of study area) governed by conductive cooling. Exceptions are observed, suggesting advective heat influx along ridges and hydrothermal circulation through cracks near the subduction trench and transform faults. In the asthenosphere of the Juan de Fuca plate, no simple monotonic relationship between seismic structure and plate age exists, but instead there is a non-monotonic slow-fast-slow VS pattern from west to east. The two slow asthenospheric VS anomalies indicate the presence of partial melt beneath both the mid-ocean ridge and the subduction trench. The partial melt beneath the trench is enigmatic.},
	keywords = {asthenosphere, Juan de Fuca, Lithosphere, plate age, thermal structure, Vs model},
	issn = {2169-9356},
	doi = {10.1029/2023JB026494},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023JB026494},
	author = {Wu, Mengyu and Wang, Hongda and Zhang, Shane and Ritzwoller, Michael H.}
}
@article {zhang_isotropic_2021,
	title = {Isotropic and azimuthally anisotropic Rayleigh wave dispersion across the Juan de Fuca and Gorda plates and U.S. Cascadia from earthquake data and ambient noise two- and three-station interferometry},
	journal = {Geophysical Journal International},
	volume = {226},
	number = {2},
	year = {2021},
	pages = {862{\textendash}883},
	abstract = {We use data from the Cascadia Initiative (CI) amphibious array and the USArray Transportable Array to construct and compare Rayleigh wave isotropic and azimuthally anisotropic phase speed maps across the Juan de Fuca and Gorda Plates extending onto the continental northwestern United States. Results from both earthquakes (28{\textendash}80~s) as well as ambient noise two- and three-station interferometry (10{\textendash}40~s) are produced. Compared with two-station interferometry, three-station direct wave interferometry provides \&gt;50~per~cent improvement in the signal-to-noise ratio and the number of dispersion measurements obtained, particularly in the noisier oceanic environment. Earthquake and ambient noise results are complementary in bandwidth and azimuthal coverage, and agree within about twice the estimated uncertainties of each method. We, therefore, combine measurements from the different methods to produce composite results that provide an improved data set in accuracy, resolution and spatial and azimuthal coverage over each individual method. A great variety of both isotropic and azimuthally anisotropic structures are resolved. Across the oceanic plate, fast directions of anisotropy with 180{\textdegree} periodicity (2ψ) generally align with palaeo-spreading directions while 2ψ amplitudes mostly increase with lithospheric age, both displaying substantial variations with depth and age. Strong (\&gt;3~per~cent) apparent anisotropy with 360{\textdegree} periodicity (1ψ) is observed at long periods (\&gt;50~s) surrounding the Cascade Range, probably caused by backscattering from heterogeneous isotropic structures.},
	issn = {0956-540X},
	doi = {10.1093/gji/ggab142},
	url = {https://doi.org/10.1093/gji/ggab142},
	author = {Zhang, Shane and Wang, Hongda and Wu, Mengyu and Ritzwoller, Michael H}
}
