Observations and interpretation of fundamental mode Rayleigh wavefields recorded by the Transportable Array (USArray)

Pollitz, Fred F.

doi:10.1029/2007jb005556

Cited by 34 publications

(56 citation statements)

References 62 publications

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“…While Burdick et al [2008] also imaged a slow Basin and Range to ∼300 km, this high-velocity anomaly beneath central Nevada is not seen in their images. This anomaly has also been imaged in other body wave tomographic studies [e.g., Humphreys and Dueker, 1994b;Dueker et al, 2001;West et al, 2009] and surface wave studies [Pollitz, 2008;Yang and Ritzwoller, 2008]. The high-velocity anomaly was tentatively interpreted as due to melt extraction [Humphreys and Dueker, 1994b], or thickened lithosphere [Dueker and Humphreys, 1993;Pollitz, 2008].…”

Section: Slow Basin and Range And The High-velocity Anomaly In Centramentioning

confidence: 90%

Mantle structure beneath the western United States and its implications for convection processes

Xue

Allen

2010

J. Geophys. Res.

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We present tomographic images of the mantle structure beneath the western United States. Our Dynamic North America Models of P and S velocity structure (DNA07‐P and DNA07‐S) use teleseismic body waves recorded at ∼600 seismic stations provided by the Earthscope Transportable Array and regional networks. DNA07‐P and ‐S benefit from the unprecedented aperture of the network while maintaining a dense station distribution providing high‐resolution body wave imaging of features through the transition zone and into the lower mantle. The main features imaged include (1) the Juan de Fuca subduction system that bottoms at ∼400 km beneath Oregon, implying interaction with the Yellowstone anomaly; (2) a low‐velocity conduit beneath Yellowstone National Park that bottoms at 500 km and dips toward the northwest; (3) shallow low‐velocity anomalies (upper 200 km) beneath the eastern Snake River Plain (ESRP) and the High Lava Plains, and a deep low‐velocity anomaly (>600 km) beneath the ESRP but not Newberry; (4) a low‐velocity “slab gap” to ∼400 km depth immediately south of the Mendocino Triple Junction and south of the Gorda slab; and (5) high‐velocity “drips” beneath the Transverse Ranges, the southern Central Valley/Sierra Nevada, and central Nevada. These observations reveal extremely heterogeneous mantle structure for the western United States and suggest that we are only just beginning to image the complex interactions between geologic objects. The transportable array allows for analysis of the relationships between these anomalies in an internally consistent single tomographic model. The DNA velocity models are available for download and slicing at http://dna.berkeley.edu.

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Section: Slow Basin and Range And The High-velocity Anomaly In Centramentioning

confidence: 90%

Mantle structure beneath the western United States and its implications for convection processes

Xue

Allen

2010

J. Geophys. Res.

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“…Here we target a subset of four tomographic models which reveal the detailed structure of the shallow mantle where melts are inferred to have been generated (Figure 7). The chosen models are PM2012, SL2013NA, DNA13, and WUSA16 that were developed by Priestley and McKenzie (2013) (Pollitz, 2008). (b) Temperature as function of depth calculated from V s profiles shown in panel (a).…”

Section: Earthquake Tomographic Modelsmentioning

confidence: 99%

Quantitative Relationships Between Basalt Geochemistry, Shear Wave Velocity, and Asthenospheric Temperature Beneath Western North America

Klöcking

White

Maclennan

et al. 2018

Geochem Geophys Geosyst

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Western North America has an average elevation that is ∼2 km higher than cratonic North America. This difference coincides with a westward decrease in average lithospheric thickness from ∼240 to <100 km. Tomographic models show that slow shear wave velocity anomalies lie beneath this region, coinciding with the pattern of basaltic magmatism. To investigate relationships between magmatism, shear wave velocity, and temperature, we analyzed a suite of >260 basaltic samples. Forward and inverse modeling of carefully selected major, trace, and rare earth elements were used to determine melt fraction as a function of depth. Basaltic melt appears to have been generated by adiabatic decompression of dry peridotite with asthenospheric potential temperatures of 1340 ± 20 °C. Potential temperatures as high as 1365 °C were obtained for the Snake River Plain. For the youngest (i.e., <5 Ma) basalts with a subplate geochemical signature, there is a positive correlation between shear wave velocities and trace element ratios such as La/Yb. The significance of this correlation is explored by converting shear wave velocity into temperature using a global empirical parameterization. Calculated temperatures agree with those determined by inverse modeling of rare earth elements. We propose that regional epeirogenic uplift of western North America is principally maintained by widespread asthenospheric temperature anomalies lying beneath a lithospheric plate, which is considerably thinner than it was in Late Cretaceous times. Our proposal accounts for the distribution and composition of basaltic magmatism and is consistent with regional heat flow anomalies.

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“…Alternatively, long period surface waves can be extracted from large teleseismic earthquakes, which usually excite long period surface waves that propagate over thousands of kilometers. New array-based tomography methods such as those developed by Yang and Forsyth (2006a, b), Pollitz (2008), and others produce dispersion maps with resolutions similar to ambient noise tomography. Our method is built on the method of Yang and Forsyth (2006a), called two-plane-wave tomography (TPWT), which uses the interference of two plane-waves to model each incoming teleseismic wavefield.…”

Section: Introductionmentioning

confidence: 96%

Surface wave tomography on a large-scale seismic array combining ambient noise and teleseismic earthquake data

2011

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We discuss two array-based tomography methods, ambient noise tomography (ANT) and two-planewave earthquake tomography (TPWT), which are capable of taking advantage of emerging large-scale broadband seismic arrays to generate high resolution phase velocity maps, but in complementary period band: ANT at 8-40 s and TPWT at 25-100 s period. Combining these two methods generates surface wave dispersion maps from 8 to 100 s periods, which can be used to construct a 3D vS model from the surface to ∼200 km depth. As an illustration, we apply the two methods to the USArray/Transportable Array. We process seismic noise data from over 1 500 stations obtained from 2005 through 2009 to produce Rayleigh wave phase velocity maps from 8 to 40 s period, and also perform TPWT using ∼450 teleseismic earthquakes to obtain phase velocity maps between 25 and 100 s period. Combining dispersion maps from ANT and TPWT, we construct a 3D vS model from the surface to a depth of 160 km in the western and central USA. These surface wave tomography methods can also be applied to other rapidly growing seismic networks such as those in China.

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Observations and interpretation of fundamental mode Rayleigh wavefields recorded by the Transportable Array (USArray)

Cited by 34 publications

References 62 publications

Mantle structure beneath the western United States and its implications for convection processes

Mantle structure beneath the western United States and its implications for convection processes

Quantitative Relationships Between Basalt Geochemistry, Shear Wave Velocity, and Asthenospheric Temperature Beneath Western North America

Surface wave tomography on a large-scale seismic array combining ambient noise and teleseismic earthquake data

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