Publications
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Azimuthal seismic anisotropy of 70 Ma Pacific‐plate upper mantle
Plate formation and evolution processes are predicted to generate upper mantle seismic anisotropy and negative vertical velocity gradients in oceanic lithosphere. However, predictions for upper mantle seismic velocity structure do not fully agree with the results of seismic experiments. The strength of anisotropy observed in the upper mantle varies widely. Further, many refraction studies observe
Authors
H. F. Mark, D. Lizarralde, J. A. Collins, Nathaniel C. Miller, G. Hirth, J. B. Gaherty, R. L. Evans
Four major Holocene earthquakes on the Reelfoot fault recorded by sackungen in the New Madrid seismic zone, USA
Three sequences of well-documented, major ~M7+ earthquakes (1811-1812 CE, ~1450 CE, and ~900 CE) in the New Madrid seismic zone, USA, contribute significantly to seismic hazard in the region. However, it is unknown whether this
Authors
Ryan D. Gold, Christopher DuRoss, Jaime E. Delano, Randall W. Jibson, Richard W. Briggs, Shannon A. Mahan, Robert Williams, D. Reide Corbett
Water salinity and inundation control soil carbon decomposition during salt marsh restoration: An incubation experiment
Coastal wetlands are a significant carbon (C) sink since they store carbon in anoxic soils. This ecosystem service is impacted by hydrologic alteration and management of these coastal habitats. Efforts to restore tidal flow to former salt marshes have increased in recent decades and are generally associated with alteration of water inundation levels and salinity. This study examined the effect of
Authors
Faming Wang, Kevin D. Kroeger, Meagan Gonneea Eagle, John W. Pohlman, Jianwu Tang
Clastic pipes and mud volcanism across Mars: Terrestrial analog evidence of past Martian groundwater and subsurface fluid mobilization
Clastic pipes are cylindrical injection features that vertically crosscut bedding with sharp contacts. Terrestrial pipes have cylindrical morphologies, massive or radially graded interiors, and raised outer rims. Increased grain size and subsequent cementation along the more porous edges makes the rims more resistant to weathering. Pipes have crosscutting relationships with other pipes due to mult
Authors
D. F. Wheatley, M. A. Chan, Chris Okubo
Landslides triggered by Hurricane Maria: Assessment of an extreme event in Puerto Rico
Hurricane Maria hit the island of Puerto Rico on 20 September 2017 and triggered more than 40,000 landslides in at least three-fourths of Puerto Rico’s 78 municipalities. The number of landslides that occurred during this event was two orders of magnitude greater than those reported from previous hurricanes. Landslide source areas were commonly limited to surficial soils but also extended into und
Authors
Erin Bessette-Kirton, Corina Cerovski-Darriau, William Schulz, Jeffrey A. Coe, Jason W. Kean, Jonathan W. Godt, Matthew A. Thomas, K. Stephen Hughes
Evaluation of temporally correlated noise in global navigation satellite system time series: Geodetic monument performance
Estimates of background noise of Global Positioning System‐derived time series of positions for 740 sites in the western United States are examined. These data consist of daily epochs of three components of displacements that are at least 9.75 years long within the interval between 2000 and 2018. We find that these time series have significant temporal correlations that could be represented as a c
Authors
John Langbein, Jerry L. Svarc
The compositions of the lunar crust and upper mantle: Spectral analysis of the inner rings of lunar impact basins
The innermost ring in impact basins exposes material originating from various depths, and can be used to study the composition of the lunar crust with depth. In this study, we conduct quantitative mineralogical analyses of the innermost ring in 13 lunar impact basins using reflectance data from the Kaguya Multiband Imager and radiative transfer modeling. We use results from recent hydrocode modeli
Authors
Myriam Lemelin, Paul G. Lucey, Katarina Miljković, Lisa R. Gaddis, Trent M. Hare, Makiko Ohtake
The formation of gullies on Mars today
A decade of high-resolution monitoring has revealed extensive activity in fresh Martian gullies. Flows within the gullies are diverse: they can be relatively light, neutral or dark, colourful or bland, and range from superficial deposits to 10 m-scale topographic changes. We observed erosion and transport of material within gullies, new terraces, freshly eroded channel segments, migrating sinuous
Authors
Colin M. Dundas, Alfred S. McEwen, Serina Diniega, Candice J. Hansen, Jim N. McElwaince
The flood lavas of Kasei Valles, Mars
Both the northern and southern arms of Kasei Valles are occupied by platy-ridged flood lavas. We have mapped these flows and examined their morphology to better understand their emplacement. The lavas were emplaced as high-flux, turbulent flows (exceeding 106 m3 s−1). Lava in southern Kasei Valles can be traced back up onto the Tharsis rise, which is also the likely source of lavas in the northern
Authors
Colin M. Dundas, Glen E. Cushing, Laszlo P. Kestay
Contaminant baselines and sediment provenance along the Puget Sound Energy Transport Corridor, 2015
The transport of coal and oil can result in contaminated soil, water, and organisms from unintended releases. Trains carrying coal and crude oil regularly pass through Puget Sound, Washington, and an increase in the number of coal and oil trains is expected in the future. This study characterized levels of potentially toxic contaminants in sediment in September 2015: arsenic, metals, and polycycli
Authors
Renee K. Takesue, Pamela L. Campbell
The Shumagin seismic gap structure and associated tsunami hazards, Alaska convergent margin
The potential for a major earthquake in the Shumagin seismic gap, and the tsunami it could generate, was reported in 1971. However, while potentially tsunamigenic splay faults in the adjacent Unimak and Semidi earthquake segments are known, such features along the Shumagin segment were undocumented until recently. To investigate margin structure and search for splay faults, we reprocessed six lega
Authors
Roland E. von Huene, John J. Miller, Anne Krabbenhoeft
Seismic velocity structure across the 2013 Craig, Alaska rupture from aftershock tomography: Implications for seismogenic conditions
The 2013 Craig, Alaska MW 7.5 earthquake ruptured along ∼150 km of the Queen Charlotte Fault (QCF), a right-lateral strike-slip plate boundary fault separating the Pacific and North American plates. Regional shear wave analyses suggest that the Craig earthquake rupturepropagated in the northward direction faster than the S-wave (supershear). Theoretical studies suggest that a bimaterial interface,
Authors
Maureen A. L. Walton, Emily C. Roland, Jacob I. Walter, Sean P. S. Gulick, Peter J. Dotray