Model Update May 2016: Upper‐Mantle Heterogeneity beneath North America from Travel‐Time Tomography with Global and USArray Data

Abstract

P-wave travel-time residuals from USArray helped improve the scale and consistency with which the mantle beneath North America is resolved. Beginning in 2008, we published a series of P-wave velocity models based on a global ray theoretical inversion of USArray and global catalog data. Here, we present the final model update, MITP_2016MAY, which includes the complete set of travel-time residuals from USArray Transportable Array (TA) in the contiguous United States. In this model, the area of high resolution extends to the eastern margin of the continent, allowing us to better estimate the location and extent of slow features in Central Virginia and New England. An increasing number of data from the TA in Alaska also allows us to recover the structure of subducting Pacific plate and Yakutat terrane. In addition to highlighting new features in the final model, we visualize and discuss the improvements to the model due to the addition of USArray data through time. Electronic Supplement: MATLAB MITP_2016MAY model and plotting scripts, figures of checkerboard tests, and animations of model evolution.

Topography of the Mantle Transition Zone Discontinuities Beneath Alaska and Its Geodynamic Implications: Constraints From Receiver Function Stacking

“…One of the most significant features in many of the tomographic images in central Alaska and along the Aleutians is a high‐velocity zone striking NE‐SW in the upper mantle (Figure ). While some earlier studies (e.g., Qi et al, ) limited this high‐velocity zone to the upper mantle, the most recent work (Burdick et al, ; Martin‐Short et al, ) found it extending to the upper mantle transition zone (MTZ) (Figure ), which is similar to findings from some of the global‐scale tomography studies (e.g., Li et al, ). Whether it also exists in the lower MTZ is unclear, due to limited vertical resolution of the tomographic inversion techniques (Martin‐Short et al, ).…”

“…Additionally, some continental‐scale tomography studies (e.g., Schaeffer & Lebedev, ) show low velocities down to about 400 km beneath western Canada. The considerable uncertainty about the depth extent of this LVZ is also reflected in the recent tomographic studies shown in Figure (Burdick et al, ; Martin‐Short et al, ).…”

“…The geometry and depth extent of the aseismic section of the subducted Pacific‐Yakutat Plates have been investigated by numerous seismic tomographic studies (Burdick et al, ; Martin‐Short et al, ; Qi et al, ; Wang & Tape, ; Zhao et al, ). One of the most significant features in many of the tomographic images in central Alaska and along the Aleutians is a high‐velocity zone striking NE‐SW in the upper mantle (Figure ).…”

“…(a–c) Vertically averaged upper mantle, upper MTZ, and lower MTZ P wave velocity anomalies from Burdick et al (). (d–f) Same as Figures a–c but from Martin‐Short et al (), which has data only in the area confined by the purple frame.…”

Evaluating the Resolution of Deep Mantle Plumes in Teleseismic Traveltime Tomography

“…Recent tomographic images using data from USArray (e.g., Burdick et al, 2017;Porritt et al, 2014;Schmandt et al, 2012) have been used to test the hypothesis that the Yellowstone hot spot has a deep mantle plume origin. Recent tomographic images using data from USArray (e.g., Burdick et al, 2017;Porritt et al, 2014;Schmandt et al, 2012) have been used to test the hypothesis that the Yellowstone hot spot has a deep mantle plume origin.…”