Shear Velocity Inversion Guided by Resistivity Structure From the PI‐LAB Experiment for Integrated Estimates of Partial Melt in the Mantle

Harmon, Nicholas; Wang, Shunguo; Rychert, C.; Constable, Steven; Kendall, J.‐M.

doi:10.1029/2021jb022202

Cited by 15 publications

(8 citation statements)

References 96 publications

(238 reference statements)

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“…Although most seismic velocity-resistivity relationships are generally not linear as shown in Carcione et al (2007), we start the joint inversion tests with the most simple scenario of correspondence map, that is a linear relationship. Linear relationships were observed previously in field data: for example, Harmon et al (2021) recovered linear relationships in the mantle for shear velocity and log resistivity near the Mid-Atlantic Ridge. The cross-plots of these properties, although not true everywhere, show an overall linear trend.…”

Section: Linear Relationship: Synthetic Testsupporting

confidence: 77%

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Joint one‐dimensional inversion of magnetotelluric data and surface‐wave dispersion curves using correspondence maps

Aquino

Marquis

Vergne

2022

Geophysical Prospecting

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We use a correspondence map to jointly invert surface‐wave dispersion curves and magnetotelluric data for subsurface shear velocity and resistivity but also for a possible relationship between them. Our first experiments consist of inversions of synthetic data computed from models linked by first‐ and second‐order polynomial relationships. Our methodology produces joint inversion model pairs from which 100% fit the ‘observed’ parameter relationship within a 5% error vs only 15% of the separate inversion pairs for the degree 1 relationship experiment. For the degree 2 relationship synthetic test, 80% of the joint inversion model pairs fit the ‘observed’ relationship within a 5% error while 45% of the separate inversion pairs. This reduces the number of acceptable models without compromising the data fit (‘reduction of non‐uniqueness'). The next experiment involves synthetic data from models of known physical properties, taken from well logs, but without a known relationship. We show how to select an appropriate polynomial degree for joint inversion when the relationship is unknown. Having validated the approach with synthetic cases, we apply our methodology to field data. We compare separate and joint inversions, and we find that the one‐dimensional subsurface models retrieved from joint inversions are more similar to previous models documented in the area than the separate inversion models.

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Section: Linear Relationship: Synthetic Testsupporting

confidence: 77%

“…Linear relationships were observed previously in field data: for example, Harmon et al. (2021) recovered linear relationships in the mantle for shear velocity and log resistivity near the Mid‐Atlantic Ridge. The cross‐plots of these properties, although not true everywhere, show an overall linear trend.…”

Section: Synthetic Testssupporting

confidence: 74%

Joint one‐dimensional inversion of magnetotelluric data and surface‐wave dispersion curves using correspondence maps

Aquino

Marquis

Vergne

2022

Geophysical Prospecting

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“…One possible explanation is that melt is only present in the asthenosphere over some sections of our study area. This has been suggested based on observations of punctuated anomalies in both shear wave velocities from surface waves (Harmon et al, 2020), magnetotelluric imaging (Wang et al, 2020), seismic imaging guided by magnetotelluric imaging (Harmon, Wang, et al, 2021), and intermittent imaging of sharp discontinuities from receiver functions (Rychert et al, 2021). Overall, the trends from the other studies suggest that no large difference in Q μ −1 in the lithosphere in comparison to the asthenosphere is predicted at the long periods of our study (Figure 7).…”

Section: The Comparisons Ofsupporting

confidence: 76%

Seismic Attenuation at the Equatorial Mid‐Atlantic Ridge Constrained by Local Rayleigh Wave Analysis From the PI‐LAB Experiment

Saikia

Rychert

Harmon

et al. 2021

Geochem Geophys Geosyst

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Determining the physical and chemical properties of the lithosphere and the asthenosphere is crucial for a better understanding of plate tectonics. Most of the Earth's tectonic plates are comprised of oceanic lithosphere, which is thought to have a relatively simple tectonic history and composition. The relative simplicity of the oceanic upper mantle makes it the ideal place for studying the lithosphere-asthenosphere system. Simple thermal models such as half space cooling or plate cooling are effective at explaining a substantial amount of the geophysical observations in the oceans (Dalton et al., 2014;Parsons & Sclater, 1977;Stein & Stein, 1992) and the composition of the mantle is well constrained from the volcanic outputs at mid-ocean ridges (Klein & Langmuir, 1987). Mid-ocean ridges are also particularly important for our understanding of the plate given that this is where the plate is formed from the upwelling of asthenospheric mantle (

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“…These kernels assume a homogeneous Earth, and therefore do not include the effects of structural heterogeneity like the previously described approaches. Although the kernels could easily be extended to 3‐D, we investigate the 2‐D case here, as a first step and for the sake of simplicity and also given that many tectonic environments, for instance rifts (e.g., Armitage et al., 2015; Chambers et al., 2021, 2019; Lavayssiere et al., 2018; Rychert et al., 2012), ridges (e.g., Harmon et al., 2020, Harmon, Wang et al., 2021, 2018; Agius et al., 2021, 2018; Eakin et al., 2018; Rychert et al., 2021, 2018; Rychert et al., 2020; Saikia et al., 2021b, 2021a; Wang et al., 2020), or subduction zone trenches (e.g., Harmon et al., 2013, Harmon, Rychert et al., 2021, 2008; Chichester et al., 2020; Cooper et al., 2020; Harmon & Rychert, 2015; Rychert et al., 2008; Schlaphorst et al., 2021; Syracuse et al., 2008) are often characterized by at least some structures that are expected to be relatively 2‐D. The idea is to determine the utility of using the simplest and computationally efficient way to implement a kernel and also recover the magnitude of velocity discontinuities.…”

Section: Introductionmentioning

confidence: 99%

2‐D Analytical P‐to‐S and S‐to‐P Scattered Wave Finite Frequency Kernels

Harmon

Rychert

Xie

et al. 2022

Geochem Geophys Geosyst

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Scattered wave imaging provides a powerful tool for understanding Earth's structure. The development of finite frequency kernels for scattered waves has the potential for improving the resolution of both the structure and magnitude of discontinuities in S‐wave velocity. Here we present a 2‐D analytical expression for teleseismic P‐to‐S and S‐to‐P scattered wave finite‐frequency kernels for a homogeneous medium. We verify the accuracy of the kernels by comparing to a spectral element method kernel calculated using SPECFEM2D. Finally, we demonstrate the ability of the kernels to recover seismic velocity discontinuities with a variety of shapes including a flat discontinuity, a discontinuity with a sharp step, a discontinuity with a smooth bump, and an undulating discontinuity. We compare the recovery using the kernel approach to expected recovery assuming the classical common conversion point (CCP) stacking approach. We find that the P‐to‐S kernel increases recovery of all discontinuity structures in comparison to CCP stacking especially for the shallowest discontinuity in the model. The S‐to‐P kernel is less successful but can be useful for recovering the curvature of shallow discontinuity undulations. Finally, although we observe some variability in the amplitude of the kernels along the discontinuities, the kernels show some potential for recovering the magnitude of the velocity contrast across a discontinuity.

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Shear Velocity Inversion Guided by Resistivity Structure From the PI‐LAB Experiment for Integrated Estimates of Partial Melt in the Mantle

Cited by 15 publications

References 96 publications

Joint one‐dimensional inversion of magnetotelluric data and surface‐wave dispersion curves using correspondence maps

Joint one‐dimensional inversion of magnetotelluric data and surface‐wave dispersion curves using correspondence maps

Seismic Attenuation at the Equatorial Mid‐Atlantic Ridge Constrained by Local Rayleigh Wave Analysis From the PI‐LAB Experiment

2‐D Analytical P‐to‐S and S‐to‐P Scattered Wave Finite Frequency Kernels

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