Evidence for Stress Localization Caused by Lithospheric Heterogeneity From Seismic Attenuation

Zhu, Zhaopeng; Bezada, Maximiliano; Byrnes, J. S.; Ford, H. A.

doi:10.1029/2021gc009987

Cited by 2 publications

(9 citation statements)

References 85 publications

(162 reference statements)

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“…This is consistent with empirical findings from previous studies that have shown that the anticorrelation between velocity structure and attenuation is strongest at depths of 100-200 km (J. S. Byrnes et al, 2019;H. Liu et al, 2022;Zhu et al, 2021). A correction for physical dispersion due to anelasticity is not made, but would not significantly change the results given the relevant periods (J.…”

Section: Whole Study Areasupporting

confidence: 91%

“…We apply attenuation measurement and imaging techniques that have been successfully used recently in different settings (Bezada, 2017; Bezada & Smale, 2019; J. S. Byrnes & Bezada, 2020; J. S. Byrnes et al., 2019; Deng et al., 2021; Zhu et al., 2021). We measure t * in the time domain by numerically attenuating an estimate of the source time function to match the observed waveforms.…”

Section: Methodsmentioning

confidence: 99%

“…This poses a challenge when applying the waveform matching approach over too large of an area because broadening of the waveforms by directivity may be misinterpreted as broadening of the waveforms by attenuation. Previous studies ignored directivity because the backazimuth is nearly constant for a small study area (Bezada, 2017; J. S. Byrnes & Bezada, 2020; J. S. Byrnes et al., 2019; Zhu et al., 2021). However, this assumption is less valid when the method is applied at this spatial scale.…”

Section: Methodsmentioning

confidence: 99%

“…Although there is some overlap in the range of values for the thin and thick lithosphere sets, the interquartile Figure 11. Δt* from this study (blue lines) and from higher resolution studies (red lines) across profiles in Wyoming (H-H', Zhu et al, 2021) and the Central Appalachian Anomaly (I-I', J. S. Byrnes et al, 2019). In each case, the mean value across the profile has been removed to facilitate the comparison.…”

Section: Relationship With Lithospheric Thickness and Thermotectonic ...mentioning

confidence: 99%

“…These studies include data from denser temporary seismic array deployments with station spacing below the nominal 70 km value of the USArray TA. In particular, the Zhu et al (2021) model for northern Wyoming and surrounding regions uses data from the BASE (e.g., Worthington et al, 2016) and CIELO (Ford et al, 2021) deployments, the latter having average station spacing of 19 km, which locally decreased to 4 km. The study of J. S. Byrnes et al (2019) across the Central Appalachians utilizes data from the MAGIC array (Long et al, 2020) with a station spacing between 30 and 15 km.…”

Section: Relationship To Local Attenuation Studiesmentioning

confidence: 99%

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Lateral Variations in Teleseismic Attenuation of the Conterminous U.S. and New Insights Derived From Its Relationship to Mantle Seismic Velocity

Bezada,

Byrnes,

Zhu

et al. 2023

JGR Solid Earth

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Much of our knowledge of the North American lithosphere comes from imaging seismic velocities. Additional constraints on the subsurface can be gained by studying seismic attenuation, which has different sensitivity to physical properties. We produce a model of lateral variations in attenuation across the conterminous U.S. by analyzing data recorded by the EarthScope Transportable Array. We divide the study area into 12 overlapping tiles and differential attenuation is measured in each tile independently; and twice for four of the tiles. Measurements are combined into a smooth map using a set of linear inversions. Comparing results for adjacent tiles and for repeated tiles shows that the imaged features are robust. The final map shows generally higher attenuation west of the Rocky Mountain Front than east of it, with significant small length scale variations superimposed on that broad pattern. In general, there is a strong anticorrelation between differential attenuation and shear wave velocities at depths of 80–250 km. However, a given change in velocity may correspond to a large or small change in attenuation, depending on the area; suggesting that different physical mechanisms are operating. In the western and south‐central U.S., as well as the Appalachians, velocity variations are large compared to attenuation changes, while the opposite is true in the north‐central and southeastern U.S. Calculations with the Very Broadband Rheology calculator show that these results are consistent with the main source of heterogeneity being temperature and melt fraction in the former regions and grain size variability in the latter ones.

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Section: Whole Study Areasupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Relationship With Lithospheric Thickness and Thermotectonic ...mentioning

confidence: 99%

Section: Relationship To Local Attenuation Studiesmentioning

confidence: 99%

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Lateral Variations in Teleseismic Attenuation of the Conterminous U.S. and New Insights Derived From Its Relationship to Mantle Seismic Velocity

Bezada,

Byrnes,

Zhu

et al. 2023

JGR Solid Earth

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Insight into the Evolution of the Eastern Margin of the Wyoming Craton from Complex, Laterally Variable Shear Wave Splitting

Birkey,

Ford,

Anderson

et al. 2024

Lithosphere

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Dense seismic arrays such as EarthScope’s Transportable Array (TA) have enabled high-resolution seismic observations that show the structure of cratonic lithosphere is more heterogeneous and complex than previously assumed. In this study, we pair TA data with data from the Bighorn Arch Seismic Experiment and the Crust and lithosphere Investigation of the Easternmost expression of the Laramide Orogeny (CIELO) to provide unprecedented detail on the seismic anisotropic structure of the eastern margin of the Wyoming Craton, where several orogens emerged from nominally strong cratonic lithosphere during the Laramide Orogeny. In this study, we use the splitting of teleseismic shear waves to characterize fabrics associated with deformation in the Earth’s crust and mantle. We constrain distinct anisotropic domains in the study area, and forward modeling shows that each of these domains can be explained by a single layer of anisotropy. Most significantly, we find a fast direction in the southern part of the Powder River Basin, which we refer to as the Thunder Basin Block (TBB), that deviates from absolute plate motion (APM). This change in splitting behavior coincides with changes in other modeled geophysical observations, such as active source P-wave velocity models, potential field modeling, and seismic attenuation analysis, which all show a significant change moving from the Bighorn Mountains to the TBB. We argue that these results correspond to structure predating the Laramide Orogeny, and most likely indicate a Neoarchean boundary preserved within the lithosphere.

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Evidence for Stress Localization Caused by Lithospheric Heterogeneity From Seismic Attenuation

Cited by 2 publications

References 85 publications

Lateral Variations in Teleseismic Attenuation of the Conterminous U.S. and New Insights Derived From Its Relationship to Mantle Seismic Velocity

Lateral Variations in Teleseismic Attenuation of the Conterminous U.S. and New Insights Derived From Its Relationship to Mantle Seismic Velocity

Insight into the Evolution of the Eastern Margin of the Wyoming Craton from Complex, Laterally Variable Shear Wave Splitting

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