@article {cortes-rivas_interactions_2025,
	title = {Interactions between megathrust behavior and forearc deformation in the Andreanof segment of the Aleutian Subduction Zone, offshore Alaska, USA},
	journal = {Geology},
	year = {2025},
	note = {_eprint: https://pubs.geoscienceworld.org/gsa/geology/article-pdf/doi/10.1130/G52810.1/7093527/g52810.pdf},
	abstract = {To explore controls on megathrust behavior and its connection with forearc deformation, we studied the Andreanof segment of the Aleutian Subduction Zone (offshore Alaska, USA), which has a simple geological history as a relatively young intra-oceanic subduction zone. Here, the forearc shows greater uplift and compression in the strongly coupled Adak region compared to the weakly coupled Atka region. Using multichannel seismic reflection data, we found that the incoming plate in both regions exhibits similar characteristics along the segment, suggesting that its properties do not account for the varying megathrust behavior and forearc deformation. Instead, differences between the Atka and Adak regions in the thickness of the methane hydrate stability zone, as marked by a bottom-simulating reflector, suggest more heat advection, and thus dewatering, in the Adak region, where the more developed fault network may enable fluid drainage, thereby lowering pore pressure at the megathrust and promoting coupling. Higher coupling allows for seismic and stress cycling that would sustain forearc permeability by faulting. Our results suggest a feedback between deformation and coupling that may be active or latent in other more complex subduction zones but in concert with or masked by other factors.},
	issn = {0091-7613},
	doi = {10.1130/G52810.1},
	url = {https://doi.org/10.1130/G52810.1},
	author = {Cort{\'e}s-Rivas, Valeria and Shillington, Donna J. and Lizarralde, Dan and Mark, Hannah}
}
@article {li_along-strike_2024,
	title = {Along-Strike Variations of Alaska Subduction Zone Structure and Hydration Determined From Amphibious Seismic Data},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {129},
	number = {3},
	year = {2024},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2023JB027800},
	pages = {e2023JB027800},
	abstract = {We develop a 3-D isotropic shear velocity model for the Alaska subduction zone using data from seafloor and land-based seismographs to investigate along-strike variations in structure. By applying ambient noise and teleseismic Helmholtz tomography, we derive Rayleigh wave group and phase velocity dispersion maps, then invert them for shear velocity structure using a Bayesian Monte Carlo algorithm. For land-based stations, we perform a joint inversion of receiver functions and dispersion curves. The forearc crust is relatively thick (35{\textendash}42 km) and has reduced lower crustal velocities beneath the Kodiak and Semidi segments, which may promote higher seismic coupling. Bristol Bay Basin crust is relatively thin and has a high-velocity lower layer, suggesting a dense mafic lower crust emplaced by the rifting processes. The incoming plate shows low uppermost mantle velocities, indicating serpentinization. This hydration is more pronounced in the Shumagin segment, with greater velocity reduction extending to 18 {\textpm} 3 km depth, compared to the Semidi segment, showing smaller reductions extending to 14 {\textpm} 3 km depth. Our estimates of percent serpentinization from VS reduction and VP/VS are larger than those determined using VP reduction in prior studies, likely due to water in cracks affecting VS more than VP. Revised estimates of serpentinization show that more water subducts than previous studies, and that twice as much mantle water is subducted in the Shumagin segment compared to the Semidi segment. Together with estimates from other subduction zones, the results indicate a wide variation in subducted mantle water between different subduction segments.},
	keywords = {Alaska subduction zone, along-strike variation, forearc crustal thickness, incoming plate hydration, seismic tomography},
	issn = {2169-9356},
	doi = {10.1029/2023JB027800},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023JB027800},
	author = {Li, Zongshan and Wiens, Douglas A. and Shen, Weisen and Shillington, Donna J.}
}
@article {brandl_discontinuous_2023,
	title = {Discontinuous Igneous Addition Along the Eastern North American Margin Beneath the East Coast Magnetic Anomaly},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {128},
	number = {8},
	year = {2023},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2023JB026459},
	month = {08/2023},
	pages = {e2023JB026459},
	abstract = {Detailed models of crustal structure at volcanic passive margins offer insight into the role of magmatism and the distribution of igneous addition during continental rifting. The Eastern North American Margin (ENAM) is a volcanic passive margin that formed during the breakup of Pangea \~{}200 Myr ago. The offshore, margin-parallel East Coast Magnetic Anomaly (ECMA) is thought to mark the locus of syn-rift magmatism. Previous widely spaced margin-perpendicular studies seismically imaged igneous addition as seaward dipping reflectors (SDRs) and high velocity lower crust (HVLC; >7.2 km/s) beneath the ECMA. Along-strike imaging is necessary to more accurately determine the distribution and volume of igneous addition during continental breakup. We use wide-angle, marine active-source seismic data from the 2014{\textendash}2015 ENAM Community Seismic Experiment to determine crustal structure beneath a \~{}370-km-long section of the ECMA. P-wave velocity models based on data from short-period ocean bottom seismometers reveal a \~{}21-km-thick crust with laterally variable lower crust velocities ranging from 6.9 to 7.5 km/s. Sections with HVLC (>7.2 km/s) alternate with two \~{}30-km-wide areas where the average velocities are less than 7.0 km/s. This variable structure indicates that HVLC is discontinuous along the margin, reflecting variable amounts of intrusion along-strike. Our results suggest that magmatism during rifting was segmented. The HVLC discontinuities roughly align with locations of Mid-Atlantic Ridge fracture zones, which may suggest that rift segmentation influenced later segmentation of the Mid-Atlantic Ridge.},
	keywords = {active source tomography, continental rifting, passive margin, seismic refraction, traveltime tomography},
	issn = {2169-9356},
	doi = {10.1029/2023JB026459},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023JB026459},
	author = {Brandl, Collin C. and Worthington, Lindsay L. and Magnani, M. Beatrice and Shillington, Donna J. and Luckie, Thomas W.}
}
@article {carchedi_investigating_2022,
	title = {Investigating Short-Period Lake-Generated Microseisms Using a Broadband Array of Onshore and Lake-Bottom Seismometers},
	journal = {Seismological Research Letters},
	volume = {93},
	number = {3},
	year = {2022},
	month = {02/2022},
	pages = {1585{\textendash}1600},
	abstract = {Recent analyses of ambient seismic noise proximal to large lakes identify excitations between periods of 0.5 and 5~s as lake-generated microseisms, though the mechanisms producing them remain unclear in the absence of distinct spectral peaks. We present a unique data set combining onshore and offshore seismometers to investigate the dominant parameters controlling water-to-solid-earth seismic coupling in a lacustrine environment. Using a set of broadband observations that include six lake-bottom seismometers, we compare signals collected both within and around Lake Malawi (Nyasa) in southeastern Africa, the fifth largest freshwater lake in the world. We document clear evidence for two peaks within the lake microseism band, with pervasive diurnal excitations between periods of \~{}0.6{\textendash}1.3 and \~{}1.3{\textendash}3~s. Variations in spectral behavior as a function of recording depth and proximity to both steep lake-floor slopes and the shoreline suggest that the spectral bands may correspond to single- and double-frequency generation processes, akin to primary and secondary ocean microseisms generated by the shoaling of wind-driven gravity waves along shorelines and wave interactions within the open body of water, respectively. However, both the absolute amplitudes and temporal evolution we observe in these two bands are complex and often inconsistent with traditional microseism theory. Therefore, these spectral bands may alternatively result from complex wave{\textendash}wave interaction at the lake surface within the enclosed northern end of the lake. The diurnal behavior of lake microseisms, as well as their polarizations, suggest that the wave energy is driven by a combination of seasonally varying nighttime winds funneled by lakeshore topography and waveguide effects. This work also provides a glimpse into seasonal variation in lacustrine ambient seismic noise and thus also into lake processes.},
	issn = {0895-0695},
	doi = {10.1785/0220210155},
	url = {https://doi.org/10.1785/0220210155},
	author = {Carchedi, Christopher James William and Gaherty, James B. and Webb, Spahr C. and Shillington, Donna J.}
}
@article {barcheck_alaska_2020,
	title = {The Alaska Amphibious Community Seismic Experiment},
	journal = {Seismological Research Letters},
	volume = {91},
	number = {6},
	year = {2020},
	month = {08/2020},
	pages = {3054{\textendash}3063},
	abstract = {The Alaska Amphibious Community Seismic Experiment (AACSE) is a shoreline-crossing passive- and active-source seismic experiment that took place from May 2018 through August 2019 along an \~{}700  km long section of the Aleutian subduction zone spanning Kodiak Island and the Alaska Peninsula. The experiment featured 105 broadband seismometers; 30 were deployed onshore, and 75 were deployed offshore in Ocean Bottom Seismometer (OBS) packages. Additional strong-motion instruments were also deployed at six onshore seismic sites. Offshore OBS stretched from the outer rise across the trench to the shelf. OBSs in shallow water (\&lt;262  m depth) were deployed with a trawl-resistant shield, and deeper OBSs were unshielded. Additionally, a number of OBS-mounted strong-motion instruments, differential and absolute pressure gauges, hydrophones, and temperature and salinity sensors were deployed. OBSs were deployed on two cruises of the R/V Sikuliaq in May and July 2018 and retrieved on two cruises aboard the R/V Sikuliaq and R/V Langseth in August{\textendash}September 2019. A complementary 398-instrument nodal seismometer array was deployed on Kodiak Island for four weeks in May{\textendash}June 2019, and an active-source seismic survey on the R/V Langseth was arranged in June 2019 to shoot into the AACSE broadband network and the nodes. Additional underway data from cruises include seafloor bathymetry and sub-bottom profiles, with extra data collected near the rupture zone of the 2018 Mw~7.9 offshore-Kodiak earthquake. The AACSE network was deployed simultaneously with the EarthScope Transportable Array (TA) in Alaska, effectively densifying and extending the TA offshore in the region of the Alaska Peninsula. AACSE is a community experiment, and all data were made available publicly as soon as feasible in appropriate repositories.},
	issn = {0895-0695},
	doi = {10.1785/0220200189},
	url = {https://doi.org/10.1785/0220200189},
	author = {Barcheck, Grace and Abers, Geoffrey A. and Adams, Aubreya N. and B{\'e}cel, Anne and Collins, John and Gaherty, James B. and Haeussler, Peter J. and Li, Zongshan and Moore, Ginevra and Onyango, Evans and Roland, Emily and Sampson, Daniel E. and Schwartz, Susan Y. and Sheehan, Anne F. and Shillington, Donna J. and Shore, Patrick J. and Webb, Spahr and Wiens, Douglas A. and Worthington, Lindsay L.}
}
@article {lynner_eastern_2019,
	title = {The Eastern North American Margin Community Seismic Experiment: An Amphibious Active- and Passive-Source Dataset},
	journal = {Seismological Research Letters},
	volume = {91},
	number = {1},
	year = {2019},
	month = {10/2019},
	pages = {533{\textendash}540},
	abstract = {The eastern North American margin community seismic experiment (ENAM-CSE) was conceived to target the ENAM Geodynamic Processes at Rifting and Subducting Margins (GeoPRISMS) primary site with a suite of both active- and passive-source seismic data that would shed light on the processes associated with rift initiation and evolution. To fully understand the ENAM, it was necessary to acquire a seismic dataset that was both amphibious, spanning the passive margin from the continental interior onto the oceanic portion of the North American plate, and multiresolution, enabling imaging of the sediments, crust, and mantle lithosphere. The ENAM-CSE datasets were collected on- and offshore of North Carolina and Virginia over a series of cruises and land-based deployments between April 2014 and June 2015. The passive-source component of the ENAM-CSE included 30 broadband ocean-bottom seismometers (OBSs) and 3 onshore broadband instruments. The broadband stations were deployed contemporaneously with those of the easternmost EarthScope Transportable Array creating a trans-margin amphibious seismic dataset. The active-source portion of the ENAM-CSE included several components: (1)~two onshore wide-angle seismic profiles where explosive shots were recorded on closely spaced geophones; (2)~four major offshore wide-angle seismic profiles acquired with an airgun source and short-period OBSs (SPOBSs), two of which were extended onland by deployments of short-period seismometers; (3)~marine multichannel seismic (MCS) data acquired along the four lines of SPOBSs and a series of other profiles along and across the margin. During the cruises, magnetic, gravity, and bathymetric data were also collected along all MCS profiles. All of the ENAM-CSE products were made publicly available shortly after acquisition, ensuring unfettered community access to this unique dataset.},
	issn = {0895-0695},
	doi = {10.1785/0220190142},
	url = {https://doi.org/10.1785/0220190142},
	author = {Lynner, Colton and J. A. Van Avendonk, Harm and B{\'e}cel, Anne and Christeson, Gail L. and Dugan, Brandon and Gaherty, James B. and Harder, Steven and Hornbach, Matthew J. and Lizarralde, Daniel and Long, Maureen D. and Magnani, M. Beatrice and Shillington, Donna J. and Aderhold, Kasey and Eilon, Zachary C. and Wagner, Lara S.}
}
@article {li_connections_2018,
	title = {Connections between subducted sediment, pore-fluid pressure, and earthquake behavior along the Alaska megathrust},
	journal = {Geology},
	volume = {46},
	number = {4},
	year = {2018},
	month = {02/2018},
	pages = {299{\textendash}302},
	abstract = {Variations in pore-fluid pressure along subduction megathrusts are often invoked to explain differences in fault slip behavior between margins. However, many other parameters vary between subduction zones, making it difficult to isolate the causes of elevated pore fluid pressures and their effects on megathrust behavior. Here we show evidence from pre-stack depth migrations of multichannel seismic reflection data along the subduction zone off the Alaska Peninsula for significant, systematic along-strike variations in the thickness, continuity, P-wave velocity, and estimated pore-fluid pressure of the subducting sediment layer that lines the shallow plate interface within 25 km of the trench. These variations appear to correlate with changes in seismicity, locking, and earthquake rupture history. The currently locked and seismically quiet Semidi segment has a continuous, thick (600{\textendash}900 m) subducted sediment layer that is characterized by low seismic velocities and elevated pore pressure (λ* ≈ 0.4{\textendash}0.8). The subducted sediment in the neighboring Shumagin Gap, a region with low geodetic coupling and abundant small earthquakes, is thinner, irregular and has lower pore pressure (λ* \&lt; 0.2{\textendash}0.3). We suggest that the thicker and weakly faulted sediment layer entering the trench at Semidi is associated with a continuous and overpressured sediment layer lining the shallow plate interface, but forms a large coherent asperity as it dewaters and consolidates at greater depths, thus favoring large earthquakes. In contrast, thinner incoming sediment disrupted by outer rise faulting at Shumagin results in a plate interface without elevated pore-fluid pressures, but which is heterogeneous and complex at all depths, contributing to creep and frequent small earthquakes.},
	issn = {0091-7613},
	doi = {10.1130/G39557.1},
	url = {https://doi.org/10.1130/G39557.1},
	author = {Li, Jiyao and Shillington, Donna J. and Saffer, Demian M. and B{\'e}cel, Anne and Nedimovi{\'c}, Mladen R. and Kuehn, Harold and Webb, Spahr C. and Keranen, Katie M. and Abers, Geoffrey A.}
}
@article {becel_tsunamigenic_2017,
	title = {Tsunamigenic structures in a creeping section of the Alaska subduction zone},
	journal = {Nature Geoscience},
	volume = {10},
	number = {8},
	year = {2017},
	note = {Publisher: Nature Publishing Group},
	pages = {609{\textendash}613},
	abstract = {Segments of subduction zones that are capable of generating tsunamigenic earthquakes appear to have characteristic structural configurations. These structures include heterogeneous plate interfaces, a small wedge of deformed sediment at the toe of the overriding plate (the frontal prism), and splay faults in the crust of the overriding plate that root within the plate boundary megathrust. Here we use seismic reflection imaging to show that these features also exist within a creeping segment of the Alaska subduction zone, the Shumagin Gap. We identify an active crustal-scale normal fault system that dips landward and resembles that involved in the 2011 Tohoku-oki earthquake in Japan. We also find that the Shumagin Gap has a small frontal prism, a deep-water splay fault, and that the plate interface here is rough and thinly sedimented. We propose that lateral propagation of rupture from a neighbouring segment into the Shumagin Gap may explain a tsunamigenic earthquake that occurred there in 1788 and that tsunamigenic potential should be considered in hazard assessments for the region. Our results demonstrate that structural configurations similar to those in Tohoku may exist in other subduction zones, including within creeping segments or segments with no record of historical megathrust earthquakes, but are under-recognized. Identifying similar configurations globally may improve our ability to anticipate regions capable of generating large tsunamis.},
	keywords = {Geodynamics, Geology, Natural hazards, seismology, Tectonics},
	issn = {1752-0908},
	doi = {10.1038/ngeo2990},
	url = {https://www.nature.com/articles/ngeo2990},
	author = {B{\'e}cel, Anne and Shillington, Donna J. and Delescluse, Matthias and Nedimovi{\'c}, Mladen R. and Abers, Geoffrey A. and Saffer, Demian M. and Webb, Spahr C. and Keranen, Katie M. and Roche, Pierre-Henri and Li, Jiyao and Kuehn, Harold}
}
@article {Shillington2016,
	title = {Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift},
	journal = {Seismological Research Letters},
	volume = {87},
	number = {6},
	year = {2016},
	month = {nov},
	pages = {1406{\textendash}1416},
	issn = {0895-0695},
	doi = {10.1785/0220160112},
	url = {https://pubs.geoscienceworld.org/srl/article/87/6/1406-1416/314187},
	author = {Shillington, Donna J. and Gaherty, James B. and Ebinger, Cynthia J. and Scholz, Christopher A. and Selway, Kate and Nyblade, Andrew A. and Bedrosian, Paul A. and Class, Cornelia and Nooner, Scott L. and Pritchard, Matthew E. and Elliott, Julie and Chindandali, Patrick R. N. and Mbogoni, Gaby and Ferdinand, Richard Wambura and Boniface, Nelson and Manya, Shukrani and Kamihanda, Godson and Saria, Elifuraha and Mulibo, Gabriel and Salima, Jalf and Mruma, Abdul and Kalindekafe, Leonard and Accardo, Natalie J. and Ntambila, Daud and Kachingwe, Marsella and Mesko, Gary T. and McCartney, Tannis and Maquay, Melania and O{\textquoteright}Donnell, J. P. and Tepp, Gabrielle and Mtelela, Khalfan and Trinhammer, Per and Wood, Douglas and Aaron, Ernest and Gibaud, Mark and Rapa, Martin and Pfeifer, Cathy and Mphepo, Felix and Gondwe, Duncan and Arroyo, Gabriella and Eddy, Celia and Kamoga, Brian and Moshi, Mary}
}
@article {shillington_link_2015,
	title = {Link between plate fabric, hydration and subduction zone seismicity in Alaska},
	journal = {Nature Geoscience},
	volume = {8},
	number = {12},
	year = {2015},
	note = {Publisher: Nature Publishing Group},
	pages = {961{\textendash}964},
	abstract = {Subduction carries water into the Earth where it can influence seismicity. Analysis of the structure of the Alaskan subduction zone suggests fluid delivery is influenced by faults in the oceanic plate that formed at the mid-ocean ridge.},
	keywords = {Geodynamics, seismology, Tectonics},
	issn = {1752-0908},
	doi = {10.1038/ngeo2586},
	url = {https://www.nature.com/articles/ngeo2586},
	author = {Shillington, Donna J. and B{\'e}cel, Anne and Nedimovi{\'c}, Mladen R. and Kuehn, Harold and Webb, Spahr C. and Abers, Geoffrey A. and Keranen, Katie M. and Li, Jiyao and Delescluse, Matthias and Mattei-Salicrup, Gabriel A.}
}
@article {Becel2015,
	title = {Origin of dipping structures in fast-spreading oceanic lower crust offshore Alaska imaged by multichannel seismic data},
	journal = {Earth and Planetary Science Letters},
	volume = {424},
	year = {2015},
	month = {aug},
	pages = {26{\textendash}37},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2015.05.016},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0012821X15003052},
	author = {B{\'e}cel, Anne and Shillington, Donna J. and Nedimovi{\'c}, Mladen R. and Webb, Spahr C. and Kuehn, Harold}
}
@article {shillington_composition_2004,
	title = {Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {5},
	number = {10},
	year = {2004},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2004GC000715},
	abstract = {New results from wide-angle seismic data collected parallel to the central Aleutian island arc require an intermediate to mafic composition for the middle crust and a mafic to ultramafic composition for the lower crust and yield lateral velocity variations that correspond to arc segmentation and trends in major element geochemistry. The 3-D ray tracing/2.5-D inversion of this sparse wide-angle data set, which incorporates independent phase interpretations and new constraints on shallow velocity structure, produces a faster and smoother result than a previously published velocity model. Middle-crustal velocities of 6.5{\textendash}7.3 km/s over depths of \~{}10{\textendash}20 km indicate an andesitic to basaltic composition. High lower-crustal velocities of 7.3{\textendash}7.7 km/s over depths of \~{}20{\textendash}35 km are interpreted as ultramafic-mafic cumulates and/or garnet granulites. The total crustal thickness is 35{\textendash}37 km. This result indicates that the Aleutian island arc has higher velocities, and thus more mafic compositions, than average continental crust, implying that significant modifications would be required for this arc to be a suitable building block for continental crust. Lateral variations in average crustal velocity (below 10 km) roughly correspond to trends in major element geochemistry of primitive (Mg \# > 0.6) lavas. The highest lower-crustal velocities (and presumably most mafic material) are detected in the center of an arc segment, between Unmak and Unalaska Islands, implying that arc segmentation exerts control over crustal composition.},
	keywords = {continental crust, crustal geophysics, island arc, major element geochemistry},
	issn = {1525-2027},
	doi = {10.1029/2004GC000715},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2004GC000715},
	author = {Shillington, Donna J. and Van Avendonk, Harm J. A. and Holbrook, W. Steven and Kelemen, Peter B. and Hornbach, Matthew J.}
}
