Direct Inversion for Three‐Dimensional Shear Wave Speed Azimuthal Anisotropy Based on Surface Wave Ray Tracing: Methodology and Application to Yunnan, Southwest China

2019 ◽  
Vol 124 (11) ◽  
pp. 11394-11413 ◽  
Author(s):  
Chuanming Liu ◽  
Huajian Yao ◽  
Hsin‐Ying Yang ◽  
Weisen Shen ◽  
Hongjian Fang ◽  
...  
Keyword(s):  
Surface Wave ◽  
Ray Tracing ◽  
Shear Wave ◽  
Wave Speed ◽  
Southwest China ◽  
Three Dimensional ◽  
Azimuthal Anisotropy ◽  
Shear Wave Speed ◽  
Direct Inversion ◽  
Wave Ray

Direct inversion of 3-D shear wave speed azimuthal and radial anisotropy from surface-wave traveltime data: methodology and applications

2020 ◽  
Author(s):  
Yao Huajian ◽  
Liu Chuanming ◽  
Hu Shaoqian
Keyword(s):  
Surface Wave ◽  
Shear Wave ◽  
Wave Speed ◽  
Joint Inversion ◽  
Azimuthal Anisotropy ◽  
Crust And Upper Mantle ◽  
Shear Wave Speed ◽  
Dispersion Data ◽  
Radial Anisotropy ◽  
Deformation Patterns

<p>Seismic anisotropy plays a key role in understanding deformation patterns of Earth’s material.  Surface wave dispersion data have been widely used to invert for azimuthal and radial anisotropy of shear wave speeds in the crust and upper mantle typically based on a 1-D pointwise inversion scheme. Here we present new methods of inverting for 3-D shear wave speed azimuthal and radial anisotropy directly from surface-wave traveltime data with the consideration of period-dependent surface wave raytracing. For the inversion of 3-D azimuthal anisotropy, our new method includes two steps: (1) inversion for the 3-D isotropic Vsv model directly from Rayleigh wave traveltime data (DSurfTomo; Fang et al., 2015, GJI); (2) joint inversion for both 3-D Vsv azimuthal anisotropy and additional 3-D isotropic Vsv perturbation. The joint inversion can significantly mitigatethe trade-off between the strong heterogeneity and azimuthal anisotropy. We apply the new method (DAzimSurfTomo) (Liu et al., 2019, JGR)to a regional array in Yunnan, southwestern China using the Rayleigh-wave phase velocity dispersion data in the period band of 5-40 s extracted from ambient noise interferometry. The obtained 3-D model of shear wave speed and azimuthal anisotropy indicates differentdeformation styles between the crust and upper mantle insouthern Yunnan. For the inversion of 3-D radial anisotropy, we presented a new inversion matrix that directly inverts Rayleigh and Love wave traveltime data jointly for 3-D Vsv and radial anisotropy parameters (Vsh/Vsv) simultaneously without intermediate steps (Hu et al., submitted to JGR).  The new approach allows for adding the smoothing or model regularization terms directly on the radial anisotropy parameters, which helps to obtain more reliable radial anisotropy structures compared to the previous division approach (Vsh/Vsv) from separate inversion of Vsv and Vsh structures. We apply this new approach (DRadiSurfTomo) to the region around the eastern Himalayan syntaxis using ambient noise dispersion data (5-40s). The obtained 3-D Vs and radial anisotropy models reveals complex distribution of crustal low velocity zones and spatial variation of deformation patterns around the eastern syntaxis region.</p>

scholarly journals Direct inversion of surface wave dispersion for three-dimensional shallow crustal structure based on ray tracing: methodology and application

2015 ◽  
Vol 201 (3) ◽  
pp. 1251-1263 ◽  
Author(s):  
Hongjian Fang ◽  
Huajian Yao ◽  
Haijiang Zhang ◽  
Yu-Chih Huang ◽  
Robert D. van der Hilst
Keyword(s):  
Surface Wave ◽  
Ray Tracing ◽  
Crustal Structure ◽  
Three Dimensional ◽  
Wave Dispersion ◽  
Surface Wave Dispersion ◽  
Direct Inversion

scholarly journals The anatomy of uppermost mantle shear-wave speed anomalies in the western U.S. from surface-wave amplification

2019 ◽  
Vol 528 ◽  
pp. 115822
Author(s):  
Lewis Schardong ◽  
Ana M.G. Ferreira ◽  
Andrea Berbellini ◽  
William Sturgeon
Keyword(s):  
Surface Wave ◽  
Shear Wave ◽  
Wave Speed ◽  
Uppermost Mantle ◽  
Wave Amplification ◽  
Shear Wave Speed

scholarly journals Spatial variations in Achilles tendon shear wave speed

2014 ◽  
Vol 47 (11) ◽  
pp. 2685-2692 ◽  
Author(s):  
Ryan J. DeWall ◽  
Laura C. Slane ◽  
Kenneth S. Lee ◽  
Darryl G. Thelen
Keyword(s):  
Achilles Tendon ◽  
Shear Wave ◽  
Wave Speed ◽  
Spatial Variations ◽  
Shear Wave Speed

scholarly journals The Relationship between Kidney Shear Wave Speed Measured Using the Elastpq Technique and Different Biomarkers of Chronic Kidney Disease

2017 ◽  
Vol 43 ◽  
pp. S210
Author(s):  
Flaviu Bob ◽  
Iulia Grosu ◽  
Ioan Sporea ◽  
Romulus Timar ◽  
Alina Popescu ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Shear Wave ◽  
Wave Speed ◽  
Shear Wave Speed ◽  
The Relationship

Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane–ethane hydrate

2003 ◽  
Vol 81 (1-2) ◽  
pp. 47-53 ◽  
Author(s):  
M B Helgerud ◽  
W F Waite ◽  
S H Kirby ◽  
A Nur
Keyword(s):  
High Pressure ◽  
Shear Wave ◽  
Pressure Dependence ◽  
Gas Hydrate ◽  
Pressure Vessel ◽  
Wave Speed ◽  
Measured Temperature ◽  
Shear Wave Speed ◽  
Temperature And Pressure ◽  
Fixed End

We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane–ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17°C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between –20 and 15°C and 0 to 105 MPa applied piston pressure. PACS No.: 61.60Lj

Diagnosis of liver fibrosis based on quantification of factors associated with shear wave speed

Choonpa Igaku ◽  
2021 ◽  
Author(s):  
Hiroko IIJIMA ◽  
Toshifumi TADA ◽  
Hiroyuki HACHIYA ◽  
Takashi NISHIMURA ◽  
Junko NISHIMURA ◽  
...  
Keyword(s):  
Liver Fibrosis ◽  
Shear Wave ◽  
Wave Speed ◽  
Shear Wave Speed ◽  
Factors Associated

scholarly journals A soft cervix, categorized by shear-wave elastography, in women with short or with normal cervical length at 18–24 weeks is associated with a higher prevalence of spontaneous preterm delivery

2018 ◽  
Vol 46 (5) ◽  
pp. 489-501 ◽  
Author(s):  
Edgar Hernandez-Andrade ◽  
Eli Maymon ◽  
Suchaya Luewan ◽  
Gaurav Bhatti ◽  
Mohammad Mehrmohammadi ◽  
...  
Keyword(s):  
Cohort Study ◽  
Preterm Delivery ◽  
Shear Wave ◽  
Wave Speed ◽  
Shear Wave Elastography ◽  
Cervical Length ◽  
Singleton Pregnancy ◽  
Short Cervix ◽  
Shear Wave Speed ◽  
Spontaneous Preterm Delivery

AbstractObjective:To determine whether a soft cervix identified by shear-wave elastography between 18 and 24 weeks of gestation is associated with increased frequency of spontaneous preterm delivery (sPTD).Materials and methods:This prospective cohort study included 628 consecutive women with a singleton pregnancy. Cervical length (mm) and softness [shear-wave speed: (SWS) meters per second (m/s)] of the internal cervical os were measured at 18–24 weeks of gestation. Frequency of sPTD <37 (sPTD<37) and <34 (sPTD<34) weeks of gestation was compared among women with and without a short (≤25 mm) and/or a soft cervix (SWS <25thpercentile).Results:There were 31/628 (4.9%) sPTD<37 and 12/628 (1.9%) sPTD<34 deliveries. The combination of a soft and a short cervix increased the risk of sPTD<37 by 18-fold [relative risk (RR) 18.0 (95% confidence interval [CI], 7.7–43.9); P<0.0001] and the risk of sPTD<34 by 120-fold [RR 120.0 (95% CI 12.3–1009.9); P<0.0001] compared to women with normal cervical length. A soft-only cervix increased the risk of sPTD<37 by 4.5-fold [RR 4.5 (95% CI 2.1–9.8); P=0.0002] and of sPTD<34 by 21-fold [RR 21.0 (95% CI 2.6–169.3); P=0.0003] compared to a non-soft cervix.Conclusions:A soft cervix at 18–24 weeks of gestation increases the risk of sPTD <37 and <34 weeks of gestation independently of cervical length.

Sensitivity of the Shear Wave Speed-Stress Relationship to Soft Tissue Material Properties and Fiber Alignment

2021 ◽  
Author(s):  
Jonathon Blank ◽  
Darryl Thelen ◽  
Matthew S. Allen ◽  
Joshua Roth
Keyword(s):  
Wave Propagation ◽  
Shear Modulus ◽  
Shear Wave ◽  
Wave Speed ◽  
Axial Stress ◽  
Beam Model ◽  
Fiber Alignment ◽  
Wave Speeds ◽  
Shear Wave Speed ◽  
Constitutive Properties

The use of shear wave propagation to noninvasively gauge material properties and loading in tendons and ligaments is a growing area of interest in biomechanics. Prior models and experiments suggest that shear wave speed primarily depends on the apparent shear modulus (i.e., shear modulus accounting for contributions from all constituents) at low loads, and then increases with axial stress when axially loaded. However, differences in the magnitudes of shear wave speeds between ligaments and tendons, which have different substructures, suggest that the tissue’s composition and fiber alignment may also affect shear wave propagation. Accordingly, the objectives of this study were to (1) characterize changes in the apparent shear modulus induced by variations in constitutive properties and fiber alignment, and (2) determine the sensitivity of the shear wave speed-stress relationship to variations in constitutive properties and fiber alignment. To enable systematic variations of both constitutive properties and fiber alignment, we developed a finite element model that represented an isotropic ground matrix with an embedded fiber distribution. Using this model, we performed dynamic simulations of shear wave propagation at axial strains from 0% to 10%. We characterized the shear wave speed-stress relationship using a simple linear regression between shear wave speed squared and axial stress, which is based on an analytical relationship derived from a tensioned beam model. We found that predicted shear wave speeds were both in-range with shear wave speeds in previous in vivo and ex vivo studies, and strongly correlated with the axial stress (R2 = 0.99). The slope of the squared shear wave speed-axial stress relationship was highly sensitive to changes in tissue density. Both the intercept of this relationship and the apparent shear modulus were sensitive to both the shear modulus of the ground matrix and the stiffness of the fibers’ toe-region when the fibers were less well-aligned to the loading direction. We also determined that the tensioned beam model overpredicted the axial tissue stress with increasing load when the model had less well-aligned fibers. This indicates that the shear wave speed increases likely in response to a load-dependent increase in the apparent shear modulus. Our findings suggest that researchers may need to consider both the material and structural properties (i.e., fiber alignment) of tendon and ligament when measuring shear wave speeds in pathological tissues or tissues with less well-aligned fibers.

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