@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 {wang_temporal_2022,
	title = {Temporal velocity variations in the northern Hikurangi margin and the relation to slow slip},
	journal = {Earth and Planetary Science Letters},
	volume = {584},
	year = {2022},
	month = {04/2022},
	pages = {117443},
	abstract = {Slow slip events (SSE) have been studied in increasing detail over the last 20 years, improving our understanding of subduction zone processes. Although the relationship between SSEs and the physical properties of their surrounding materials is still not well-understood, the northern Hikurangi margin in New Zealand is the site of relatively shallow (<10 km deep), frequent SSEs, providing excellent opportunities for near-field investigations. From September to October 2014, an SSE occurred with more than 250 mm slip, and was recorded successfully by the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) deployment. This study applies scattered wave interferometry to ambient noise data acquired by nine HOBITSS ocean bottom seismometers (OBS) to study the seismic velocity variations related to the SSE. Single station cross-component correlations are computed within a period band that focuses on the upper plate in our study region. The average velocity variations display a decrease on the order of 0.05\% during the SSE, followed by an increase of similar magnitude afterwards. We suggest two possibilities. The first possibility, which has been suggested by other seismological observations, is that the SSE causes a low-permeability seal on the plate boundary to break. The break allows fluid to migrate into the upper plate, causing a seismic velocity decrease during the SSE because of increased pore fluid volume in the upper plate. Under this model, after the SSE, the fluids in the upper plate diffuse gradually and the velocity increases again. The second possibility is the velocity changes are related to changes in crustal strain during the slow slip cycle, whereby elastic strain accumulates prior to the SSE, causing contraction and reduction of porosity and therefore increase of velocity above the SSE source (the seismic velocity increases between SSEs). During the SSE the upper plate goes into extension as the elastic strain is released, which results in dilation and a porosity increase (seismic velocity reduction). After the SSE, stress and strain accumulate again, causing a porosity decrease and a velocity increase.},
	keywords = {ambient noise, seismic velocity variations, slow slip event, the Hikurangi subduction zone},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2022.117443},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X22000796},
	author = {Wang, Weiwei and Savage, Martha K. and Yates, Alexander and Zal, Hubert J. and Webb, Spahr and Boulton, Carolyn and Warren-Smith, Emily and Madley, Megan and Stern, Tim and Fry, Bill and Mochizuki, Kimihiro and Wallace, Laura}
}
@article {russell_lithosphere_2021,
	title = {Lithosphere Structure and Seismic Anisotropy Offshore Eastern North America: Implications for Continental Breakup and Ultra-Slow Spreading Dynamics},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {126},
	number = {12},
	year = {2021},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JB022955},
	month = {11/2021},
	pages = {e2021JB022955},
	abstract = {The breakup of supercontinent Pangea occurred \~{}200 Ma forming the Eastern North American Margin (ENAM). Yet, the precise timing and mechanics of breakup and onset of seafloor spreading remain poorly constrained. We investigate the relict lithosphere offshore eastern North America using ambient-noise Rayleigh-wave phase velocity (12{\textendash}32 s) and azimuthal anisotropy (17{\textendash}32 s) at the ENAM Community Seismic Experiment (CSE). Incorporating previous constraints on crustal structure, we construct a shear velocity model for the crust and upper \~{}60 km of the mantle beneath the ENAM-CSE. A low-velocity lid (VS of 4.4{\textendash}4.55 km/s) is revealed in the upper 15{\textendash}20 km of the mantle that extends \~{}200 km from the margin, terminating at the Blake Spur Magnetic Anomaly (BSMA). East of the BSMA, velocities are fast (>4.6 km/s) and characteristic of typical oceanic mantle lithosphere. We interpret the low-velocity lid as stretched continental mantle lithosphere embedded with up to \~{}15\% retained gabbro. This implies that the BSMA marks successful breakup and onset of seafloor spreading \~{}170 Ma, consistent with ENAM-CSE active-source studies that argue for breakup \~{}25 Myr later than previously thought. We observe margin-parallel Rayleigh-wave azimuthal anisotropy (2\%{\textendash}4\% peak-to-peak) in the lithosphere that approximately correlates with absolute plate motion (APM) at the time of spreading. We hypothesize that lithosphere formed during ultra-slow seafloor spreading records APM-modified olivine fabric rather than spreading-parallel fabric typical of higher spreading rates. This work highlights the importance of present-day passive margins for improving understanding of the fundamental rift-to-drift transition.},
	keywords = {ambient noise, continental rifting, eastern North American margin, oceanic lithosphere, seismic anisotropy, surface-wave tomography},
	issn = {2169-9356},
	doi = {10.1029/2021JB022955},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JB022955},
	author = {Russell, J. B. and Gaherty, J. B.}
}
@article {lynner_crustal_2017,
	title = {Crustal structure across the eastern North American margin from ambient noise tomography},
	journal = {Geophysical Research Letters},
	volume = {44},
	number = {13},
	year = {2017},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL073500},
	pages = {6651{\textendash}6657},
	abstract = {Passive tectonic margins, like the eastern North American margin (ENAM), represent the meeting of oceanic and continental material where no active deformation is occurring. The recent ENAM Community Seismic Experiment provides an opportunity to examine the crustal structure across the ENAM owing to the simultaneous deployment of offshore and onshore seismic instrumentation. Using Rayleigh wave phase and group velocities derived from ambient noise data, we invert for shear velocity across the ENAM. We observe a region of transitional crustal thicknesses that connects the oceanic and continental crusts. Associated with the transitional crust is a localized positive gravitational anomaly. Farther east, the East Coast magnetic anomaly (ECMA) is located at the intersection of the transitional and oceanic crusts. We propose that underplating of dense magmatic material along the bottom of the transitional crust is responsible for the gravitational anomaly and that the ECMA demarks the location of initial oceanic crustal formation.},
	keywords = {ambient noise, crustal structure, eastern North American margin, passive margin},
	issn = {1944-8007},
	doi = {10.1002/2017GL073500},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2017GL073500},
	author = {Lynner, Colton and Porritt, Robert W.}
}
@article {yao_structure_2011,
	title = {Structure of young East Pacific Rise lithosphere from ambient noise correlation analysis of fundamental- and higher-mode Scholte-Rayleigh waves},
	journal = {Nouveaux d{\'e}veloppements de l{\textquoteright}imagerie et du suivi temporel {\`a} partir du bruit sismique},
	volume = {343},
	number = {8},
	year = {2011},
	month = {sep},
	pages = {571{\textendash}583},
	abstract = {Inter-station Green{\textquoteright}s functions estimated from ambient noise studies have been widely used to investigate crustal structure. However, most studies are restricted to continental areas and use fundamental-mode surface waves only. In this study, we recover inter-station surface (Scholte-Rayleigh) wave empirical Green{\textquoteright}s function (EGFs) of both the fundamental- and the first-higher mode using one year of continuous seismic noise records on the vertical component from 28 ocean bottom seismographs deployed in the Quebrada/Discovery/Gofar transform faults region on the East Pacific Rise. The average phase-velocity dispersion of the fundamental mode (period band 2{\textendash}30s) and the first-higher mode (period band 3{\textendash}7s) from all EGFs are used to invert for the 1-D average, shear-velocity structure in the crust and uppermost mantle using a model-space search algorithm. The preferred shear-velocity models reveal low velocities (4.29km/s) between Moho and 25km depth below sea-surface, suggesting the absence of a fast uppermost mantle lid in this young (0{\textendash}2Myr) oceanic region. An even more pronounced low-velocity zone, with shear velocities \~{}3.85km/s, appears at a depth between 25{\textendash}40km below sea-surface. Along with previous results, our study indicates that the shear velocity in the uppermost oceanic mantle increases with increasing seafloor age, consistent with age-related lithospheric cooling. R{\'e}sum{\'e} Les fonctions de Green estim{\'e}es {\`a} partir de l{\textquoteright}analyse du bruit ambiant ont beaucoup {\'e}t{\'e} utilis{\'e}es pour {\'e}tudier la structure de la cro{\^u}te terrestre. La plupart de ces travaux sont toutefois limit{\'e}s aux zones continentales, et ne consid{\`e}rent que le mode fondamental des ondes de surface. Dans cette {\'e}tude, les fonctions de Green empiriques (EGFs) du mode fondamental et du premier mode sup{\'e}rieur des ondes de surface (Scholte-Rayleigh) sont reconstruites {\`a} partir d{\textquoteright}une ann{\'e}e d{\textquoteright}enregistrements continus de la composante verticale du bruit sismique sur 28 ocean bottom seismometers (OBSs) d{\'e}ploy{\'e}s dans la r{\'e}gion des failles transformantes Quebrada/Discovery/Gofar, le long de la dorsale oc{\'e}anique du Pacifique Est. La dispersion moyenne des vitesses de phase du mode fondamental (dans la bande de p{\'e}riode 2{\textendash}30s) et du premier mode sup{\'e}rieur (dans la bande 3{\textendash}7s), issus des EGFs, est utilis{\'e}e pour d{\'e}terminer un mod{\`e}le moyen 1D de la vitesse des ondes de cisaillement dans la cro{\^u}te et le manteau sup{\'e}rieur {\`a} partir d{\textquoteright}un algorithme de recherche dans l{\textquoteright}espace mod{\`e}le. Le mod{\`e}le de vitesse des ondes de cisaillement r{\'e}sultant pr{\'e}sente une couche de faible vitesse (4,29km/s) entre le Moho et 25km sous le niveau de la mer, ce qui sugg{\`e}re l{\textquoteright}absence de couche superficielle rapide dans le manteau sup{\'e}rieur de cette jeune r{\'e}gion oc{\'e}anique (0{\textendash}2millions d{\textquoteright}ann{\'e}es). Une zone de faible vitesse encore plus prononc{\'e}e, avec une vitesse de cisaillement de \~{}3,85km/s, appara{\^\i}t entre 25 et 40km sous le niveau de la mer. Combin{\'e}e avec des r{\'e}sultats ant{\'e}rieurs, notre {\'e}tude montre que la vitesse de cisaillement dans le manteau oc{\'e}anique sup{\'e}rieur augmente avec l{\textquoteright}{\^a}ge du fond oc{\'e}anique, ce qui est en accord avec le refroidissement dans le temps de la lithosph{\`e}re.},
	keywords = {ambient noise, Bruit ambiant, Dorsale Est Pacifique, East Pacific Rise, Fundamental- and higher-mode Scholte-Rayleigh waves, Lithosphere, Low-velocity zone, Manteau oc{\'e}anique sup{\'e}rieur, Modes fondamental et sup{\'e}rieur des ondes de Scholte-Rayleigh, Oceanic Uppermost Mantle, Zone de faible vitesse},
	issn = {1631-0713},
	doi = {10.1016/j.crte.2011.04.004},
	url = {https://www.sciencedirect.com/science/article/pii/S1631071311000952},
	author = {Yao, Huajian and Gou{\'e}dard, Pierre and Collins, John A. and McGuire, Jeffrey J. and van der Hilst, Robert D.}
}
