@article {wang_slab_2025,
	title = {Slab Morphology, Dehydration, and Sub-Arc Melting Beneath the Alaska Peninsula Revealed by Body-Wave Tomography},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {130},
	number = {3},
	year = {2025},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2024JB029814},
	pages = {e2024JB029814},
	abstract = {Abstract The Alaska Peninsula has a long history of plate subduction with along-arc variations in volcanic eruption styles and geochemistry. However, the sub-arc melting processes that feed these volcanoes are unclear. The Alaska slab morphology below 200 km depth remains debated due to limited seismic data and thus low tomography resolution in this region. Here we utilize the newly available regional and teleseismic data to build 3-D high-resolution VP and VS models to 660 km depth. We find that the high-velocity Pacific Plate subducts to the bottom of the mantle transition zone (MTZ) with complex deformation and gaps. In the southwest, we observe a wide gap in the high-velocity slab at 200{\textendash}500 km depths. Toward the northeast, the slab becomes more continuous extending to the MTZ with a few holes below 200 km. We interpret these gaps as a slab tear that coincides with the subducted ancient Kula-Pacific Ridge. We also invert for 3-D VP and VP/VS models to 200 km depth with higher resolution and find strong along-strike changes in slab dehydration and sub-arc melting, indicated by low VP and high VP/VS anomalies. Slab dehydration and sub-arc melting are most extensive below the Pavlof and Shumagin segments in the southwest, becoming limited below the Chignik and Chirikof segments in the northeast, and extensive again beneath the Kodiak segment further to the northeast. We propose that the variations of slab hydration at the outer rise significantly influence slab dehydration at greater depths and further control sub-arc melting beneath the Alaska Peninsula.},
	keywords = {Alaska peninsula, Body-wave tomography, slab dehydration, slab morphology, sub-arc melting, subduction zones, tomography, volcano},
	doi = {https://doi.org/10.1029/2024JB029814},
	author = {Wang, Fan and Wei, S. Shawn and Ruppert, Natalia A. and Zhang, Haijiang and Wu, Jonny}
}
@article {russell_rayleigh_2022,
	title = {Rayleigh Wave Attenuation and Amplification Measured at Ocean-Bottom Seismometer Arrays using Helmholtz Tomography},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {n/a},
	number = {n/a},
	year = {2022},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JB025174},
	month = {10/2022},
	pages = {e2022JB025174},
	abstract = {Shear attenuation provides insights into the physical and chemical state of the upper mantle. Yet, observations of attenuation are infrequent in the oceans, despite recent proliferation of arrays of ocean-bottom seismometers (OBS). Studies of attenuation in marine environments must overcome unique challenges associated with strong oceanographic noise at the seafloor and data loss during OBS recovery in addition to untangling the competing influences of elastic focusing, local site amplification, and anelastic attenuation on surface-wave amplitudes. We apply Helmholtz tomography to OBS data to simultaneously resolve array-averaged Rayleigh wave attenuation and maps of site amplification at periods of 20{\textendash}150 s. The approach explicitly accounts for elastic focusing and defocusing due to lateral velocity heterogeneity using wavefield curvature. We validate the approach using realistic wavefield simulations at the NoMelt Experiment and Juan de Fuca (JdF) plate, which represent endmember open-ocean and coastline-adjacent environments, respectively. Focusing corrections are successfully recovered at both OBS arrays, including at periods < 35 s at JdF where coastline effects result in strong multipathing. When applied to real data, our observations of Rayleigh wave attenuation at NoMelt and JdF revise previous estimates. At NoMelt, we observe a low attenuation lithospheric layer (Qμ>1500) overlying a highly attenuating asthenospheric layer (Qμ\~{}50{\textendash}70). At JdF, we find a broad peak in attenuation (Qμ\~{}50{\textendash}60) centered at a depth of 100{\textendash}130 km. We also report strong local site amplification at the JdF Ridge (>10\% at 31 s period), which can be used to refine models of crust and shallow mantle structure.},
	keywords = {amplification, attenuation, Helmholtz, ocean-bottom seismology, surface waves, tomography},
	issn = {2169-9356},
	doi = {10.1029/2022JB025174},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JB025174},
	author = {Russell, Joshua B. and Dalton, Colleen A.}
}
@article {le_seismic_2022,
	title = {Seismic Constraints on Crustal and Uppermost Mantle Structure Beneath the Hawaiian Swell: Implications for Plume-Lithosphere Interactions},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {127},
	number = {11},
	year = {2022},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021JB023822},
	month = {10/2022},
	pages = {e2021JB023822},
	abstract = {We infer the lithospheric structure beneath the Hawaiian Swell based on a joint inversion of ambient noise and teleseismic Rayleigh waves collected during the PLUME experiment. These combined datasets let us use Rayleigh waves with a period range of 8{\textendash}50 s that provides imaging resolution for the shallow lithosphere and constrains interactions between the upwelling plume and migrating plate. We find an elongated low-velocity anomaly beneath the lithosphere along the island chain that connects to the plume conduit, consistent with the melting region associated with a restite hotspot swell root that has mechanically eroded the base of its overlying lithosphere. It could also be consistent with a plume refracted by the overriding plate motion if the plume could manage to deeply erode the lithospheric base, as only a more viscous restite root is seen to do in thermomechanical experiments. There is also a low-velocity body beneath the North Arch that coincides with the location of recent off-chain volcanic fields discovered there. Its location relative to the Molokai Fracture Zone (MFZ) supports the concept that swell-root material has preferentially spread beneath the younger side of the MFZ. We also find a clear low-velocity anomaly associated with the uppermost \~{}50 km of the fracture zone lithosphere. The relatively well-resolved shallow lithospheric structure determined here allows us to estimate the volumes of underplating and the total flux of the rising plume material that is added beneath the Hawaiian lithosphere, which we constrain to be in the range of 0.5{\textendash}0.6 km3/yr.},
	keywords = {ambient noise, Hawaiian swell, Rayleigh waves, tomography, underplating},
	issn = {2169-9356},
	doi = {10.1029/2021JB023822},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JB023822},
	author = {Le, Ba Manh and Yang, Ting and Morgan, Jason P.}
}
@article {brunsvik_mantle_2021,
	title = {Mantle Structure and Flow Across the Continent-Ocean Transition of the Eastern North American Margin: Anisotropic S-Wave Tomography},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {22},
	number = {12},
	year = {2021},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021GC010084},
	pages = {e2021GC010084},
	abstract = {Little has been seismically imaged through the lithosphere and mantle at rifted margins across the continent-ocean transition. A 2014{\textendash}2015 community seismic experiment deployed broadband seismic instruments across the shoreline of the eastern North American rifted margin. Previous shear-wave splitting along the margin shows several perplexing patterns of anisotropy, and by proxy, mantle flow. Neither margin parallel offshore fast azimuths nor null splitting on the continental coast obviously accord with absolute plate motion, paleo-spreading, or rift-induced anisotropy. Splitting measurements, however, offer no depth constraints on anisotropy. Additionally, mantle structure has not yet been imaged in detail across the continent-ocean transition. We used teleseismic S, SKS, SKKS, and PKS splitting and differential travel times recorded on ocean-bottom seismometers, regional seismic networks, and EarthScope Transportable Array stations to conduct joint isotropic/anisotropic tomography across the margin. The velocity model reveals a transition from fast, thick, continental keel to low velocity, thinned lithosphere eastward. Imaged short wavelength velocity anomalies can be largely explained by edge-driven convection or shear-driven upwelling. We also find that layered anisotropy is prevalent across the margin. The anisotropic fast polarization is parallel to the margin within the asthenosphere. This suggests margin parallel flow beneath the plate. The lower oceanic lithosphere preserves paleo-spreading-parallel anisotropy, while the continental lithosphere has complex anisotropy reflecting several Wilson cycles. These results demonstrate the complex and active nature of a margin which is traditionally considered tectonically inactive.},
	keywords = {anisotropy, continent-ocean transition, eastern North American margin, shear wave splitting, tomography},
	issn = {1525-2027},
	doi = {10.1029/2021GC010084},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021GC010084},
	author = {Brunsvik, Brennan R. and Eilon, Zachary C. and Lynner, Colton}
}
@article {merz_seismicity_2019,
	title = {Seismicity and Velocity Structure of Lo{\textquoteright}ihi Submarine Volcano and Southeastern Hawai{\textquoteright}i},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {124},
	number = {11},
	year = {2019},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2019JB018168},
	pages = {11380{\textendash}11393},
	abstract = {Hundreds of earthquakes were recorded during a nine-month ocean bottom seismometer deployment surrounding Lo{\textquoteright}ihi submarine volcano, Hawai{\textquoteright}i. The 12-station ocean bottom seismometer network widened the aperture of earthquake detection around the Big Island, allowing better constraints on the location of seismicity offshore Hawai{\textquoteright}i. Although this deployment occurred during a time of volcanic quiescence for Lo{\textquoteright}ihi, it establishes an important basis for background seismicity of the volcano. Offshore seismicity during this study was dominated by events located in the mantle fault zone at depths of 25{\textendash}40 km. These events reflect rupture on preexisting faults in the lower lithosphere caused by stresses induced by volcano loading and flexure of the Pacific Plate (Pritchard et al., 2007, https://doi.org/10.1111/j.1365-246X.2006.03169.x; Wolfe et al., 2004, https://doi.org/10.1029/2003GC000618). Tomography was performed using double-difference seismic tomography and showed shallow velocities to be slower than the regional velocity model (HG50; Klein, 1981, https://pubs.geoscienceworld.org/ssa/bssa/article/71/5/1503/118231/A-linear-gradient-crustal-model-for-south-Hawaii). A broad, low-velocity anomaly was observed from 20{\textendash}40-km depth, and is suggestive of the central plume conduit that supplies magma to Lo{\textquoteright}ihi and the active volcanoes of the Big Island. A localized high-velocity body is observed 4{\textendash}6-km depth beneath Lo{\textquoteright}ihi{\textquoteright}s summit, extending 10 km to the north and south. Following Lo{\textquoteright}ihi{\textquoteright}s active rift zones and crossing the summit, this high-velocity body is characteristic of intrusive material. Two low-velocity anomalies are observed below the oceanic crust, interpreted as melt accumulation beneath Lo{\textquoteright}ihi and magmatic underplating beneath Hawai{\textquoteright}i Island.},
	keywords = {Hawai{\textquoteright}i, hot spot, Lo{\textquoteright}ihi seamount, tomography, volcano seismology},
	issn = {2169-9356},
	doi = {10.1029/2019JB018168},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JB018168},
	author = {Merz, D. K. and Caplan-Auerbach, J. and Thurber, C. H.}
}
@article {van_avendonk_deep_2014,
	title = {Deep crustal structure of an arc-continent collision: Constraints from seismic traveltimes in central Taiwan and the Philippine Sea},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {119},
	number = {11},
	year = {2014},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2014JB011327},
	pages = {8397{\textendash}8416},
	abstract = {The collision of continental crust of the Eurasian Plate with the overriding Luzon Arc in central Taiwan has led to compression, uplift, and exhumation of rocks that were originally part of the Chinese rifted margin. Though the kinematics of the fold-thrust belt on the west side of the orogen has been described in detail, the style of deformation in the lower crust beneath Taiwan is still not well understood. In addition, the fate of the Luzon Arc and Forearc in the collision is also not clear. Compressional wave arrival times from active-source and earthquake seismic data from the Taiwan Integrated Geodynamic Research program constrain the seismic velocity structure of the lithosphere along transect T5, an east-west corridor in central Taiwan. The results of our analysis indicate that the continental crust of the Eurasian margin forms a broad crustal root beneath central Taiwan, possibly with a thickness of 55 km. Compressional seismic velocities beneath the Central Range of Taiwan are as low as 5.5 km/s at 25 km depth, whereas P wave seismic velocities in the middle crust on the eastern flank of the Taiwan mountain belt average 6.5{\textendash}7.0 km/s. This suggests that the incoming sediments and upper crust of the Eurasian Plate are buried to midcrustal depth in the western flank of the orogen before they are exhumed in the Central Range. To the east, the Luzon Arc and Forearc are deformed beneath the Coastal Range of central Taiwan. Fragments of the rifted margin of the South China Sea that were accreted in the early stages of the collision form a new backstop that controls the exhumation of Eurasian strata to the west in this evolving mountain belt.},
	keywords = {arc-continent collision, earthquakes, Philippine Sea Plate, seismic refraction, Taiwan, tomography},
	issn = {2169-9356},
	doi = {10.1002/2014JB011327},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2014JB011327},
	author = {Van Avendonk, H. J. A. and Kuo-Chen, H. and McIntosh, K. D. and Lavier, L. L. and Okaya, D. A. and Wu, F. T. and Wang, C. Y. and Lee, C. S. and Liu, C. S.}
}
@article {roland_seismic_2012,
	title = {Seismic velocity constraints on the material properties that control earthquake behavior at the Quebrada-Discovery-Gofar transform faults, East Pacific Rise},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {117},
	number = {B11},
	year = {2012},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2012JB009422},
	abstract = {Mid-ocean ridge transform faults (RTFs) vary strongly along strike in their ability to generate large earthquakes. This general observation suggests that local variations in material properties along RTFs exert a primary control on earthquake rupture dynamics. We explore these relationships by examining the seismic structure of two RTFs that have distinctly different seismic coupling. We determine the seismic velocity structure at the Gofar and Quebrada faults on the East Pacific Rise (EPR) using P wave traveltime tomography with data from two active-source wide-angle refraction lines crossing the faults. We image low-velocity zones (LVZs) at both faults, where P wave velocities are reduced by as much as 0.5{\textendash}1.0 km/s (\~{}10{\textendash}20\%) within a several kilometer wide region. At the Gofar fault, the LVZ extends through the entire crust, into the seismogenic zone. We rule out widespread serpentinization as an explanation for the low velocities, owing to the lack of a corresponding signal in the locally measured gravity field. The reduced velocities can be explained if the plate boundary region is composed of fault material with enhanced fluid-filled porosity (1.5{\textendash}8\%). Local seismic observations indicate that the high-porosity region lies within a \~{}10 km long portion of the fault that fails in large swarms of microearthquakes and acts as a barrier to the propagation of large (M \~{} 6.0) earthquakes. Tomographic images of fault structure combined with observed earthquake behavior suggest that EPR transform segments capable of generating large earthquakes have relatively intact gabbro within the seismogenic zone, whereas segments that slip aseismically or via earthquake swarms are composed of highly fractured, >=2 km wide damage zones that extend throughout the crust.},
	keywords = {fault structure, marine seismology, rupture dynamics, tomography, transform fault},
	issn = {2156-2202},
	doi = {10.1029/2012JB009422},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2012JB009422},
	author = {Roland, Emily and Lizarralde, Dan and McGuire, Jeffrey J. and Collins, John A.}
}
