<i>P</i>‐Wave Tomography for 3‐D Radial and Azimuthal Anisotropy Beneath Greenland and Surrounding Regions

Toyokuni, Genti; Zhao, Dapeng

doi:10.1029/2021ea001800

Cited by 5 publications

(4 citation statements)

References 65 publications

(156 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given the inconsistent coupling of instruments in the data set we used, attempting to use amplitude information to constrain density would likely be ill‐conceived, although future advances in instrumentation may someday make this a worthwhile pursuit (e.g., Yuan et al., 2015). Additionally, since CZ materials may exhibit significant seismic anisotropy (Eppinger et al., 2021; Novitsky et al., 2018), accounting for anisotropy may further improve FWT results, although this would likely require some prior information about the anisotropy of the study site or 3D, multi‐component data coverage (e.g., Toyokuni & Zhao, 2021).…”

Section: Discussionmentioning

confidence: 99%

2D Near‐Surface Full‐Waveform Tomography Reveals Bedrock Controls on Critical Zone Architecture

Eppinger,

Holbrook,

Liu

et al. 2024

Earth and Space Science

View full text Add to dashboard Cite

For decades, seismic imaging methods have been used to study the critical zone, Earth's thin, life‐supporting skin. The vast majority of critical zone seismic studies use traveltime tomography, which poorly resolves heterogeneity at many scales relevant to near‐surface processes, therefore limiting progress in critical zone science. Full‐waveform tomography can overcome this limitation by leveraging more seismic data and enhancing the resolution of geophysical imaging. In this study, we apply 2D full‐waveform tomography to match the phases of observed seismograms and elucidate previously undetected heterogeneity in the critical zone at a well‐studied catchment in the Laramie Range, Wyoming. In contrast to traveltime tomograms from the same data set, our results show variations in depth to bedrock ranging from 5 to 60 m over lateral scales of just tens of meters and image steep low‐velocity anomalies suggesting hydrologic pathways into the deep critical zone. Our results also show that areas with thick fractured bedrock layers correspond to zones of slightly lower velocities in the deep bedrock, while zones of high bedrock velocity correspond to sharp vertical transitions from bedrock to saprolite. By corroborating these findings with borehole imagery, we hypothesize that lateral changes in bedrock fracture density majorly impact critical zone architecture. Borehole data also show that our full‐waveform tomography results agree significantly better with velocity logs than previously published traveltime tomography models. Full‐waveform tomography thus appears unprecedentedly capable of imaging the spatially complex porosity structure crucial to critical zone hydrology and processes.

show abstract

Section: Discussionmentioning

confidence: 99%

2D Near‐Surface Full‐Waveform Tomography Reveals Bedrock Controls on Critical Zone Architecture

Eppinger,

Holbrook,

Liu

et al. 2024

Earth and Space Science

View full text Add to dashboard Cite

show abstract

“…During the past decade, the RAN tomographic method has been applied extensively to study the 3-D Vp structure and dynamics of the crust and upper mantle in many regions, including NE Japan (Wang and Zhao 2013;Ishise et al 2018), SW Japan (Wang and Zhao 2013), South Kuril (Niu et al 2016), Eastern China (Wang et al 2014;Jiang et al 2021;Liang et al 2022), Tibet (Zhang et al 2021), the Philippines (Fan and Zhao 2019), Alaska (Gou et al 2019a), Cascadia (Zhao and Hua 2021), Southern California (Yu and Zhao 2018;Yu et al 2020b), Alps (Hua et al 2017), Africa (Yu et al 2020a), Greenland (Toyokuni and Zhao 2021), and Antarctica (Zhang et al 2020).…”

Section: Radial Anisotropy Tomographymentioning

confidence: 99%

“…P-wave AAN tomography has been also applied to study the 3-D structure and dynamics beneath continental regions (Figs. 5, 6 and 7), including Mainland China (Tian and Zhao 2013;Huang et al 2014;Wei et al 2016;Jiang et al 2021;Jia et al 2022), the Tibetan Plateau (Wei et al 2013;Zhang et al 2017;Yang et al 2022a), western and central USA (Huang and Zhao 2013;Yu and Zhao 2018;Wang and Zhao 2019a;Wang et al 2022a;Yang et al 2022b), Africa (Yu et al 2020a), Turkey (Wang et al 2020), and Greenland (Toyokuni and Zhao 2021). Figure 5 shows Vp AAN tomography beneath China (Wei et al 2016), revealing that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet.…”

mentioning

confidence: 99%

Seismic Anisotropy Tomography and Mantle Dynamics

et al. 2023

Self Cite

View full text Add to dashboard Cite

Seismic anisotropy tomography is the updated geophysical imaging technology that can reveal 3-D variations of both structural heterogeneity and seismic anisotropy, providing unique constraints on geodynamic processes in the Earth’s crust and mantle. Here we introduce recent advances in the theory and application of seismic anisotropy tomography, thanks to abundant and high-quality data sets recorded by dense seismic networks deployed in many regions in the past decades. Applications of the novel techniques led to new discoveries in the 3-D structure and dynamics of subduction zones and continental regions. The most significant findings are constraints on seismic anisotropy in the subducting slabs. Fast-velocity directions (FVDs) of azimuthal anisotropy in the slabs are generally trench-parallel, reflecting fossil lattice-preferred orientation of aligned anisotropic minerals and/or shape-preferred orientation due to transform faults produced at the mid-ocean ridge and intraslab hydrated faults formed at the outer-rise area near the oceanic trench. The slab deformation may play an important role in both mantle flow and intraslab fabric. Trench-parallel anisotropy in the forearc has been widely observed by shear-wave splitting measurements, which may result, at least partly, from the intraslab deformation due to outer-rise yielding of the incoming oceanic plate. In the mantle wedge beneath the volcanic front and back-arc areas, FVDs are trench-normal, reflecting subduction-driven corner flows. Trench-normal FVDs are also revealed in the subslab mantle, which may reflect asthenospheric shear deformation caused by the overlying slab subduction. Toroidal mantle flow is observed in and around a slab edge or slab window. Significant azimuthal and radial anisotropies occur in the big mantle wedge beneath East Asia, reflecting hot and wet upwelling flows as well as horizontal flows associated with deep subduction of the western Pacific plate and its stagnation in the mantle transition zone. The geodynamic processes in the big mantle wedge have caused craton destruction, back-arc spreading, and intraplate seismic and volcanic activities. Ductile flow in the middle-lower crust is clearly revealed as prominent seismic anisotropy beneath the Tibetan Plateau, which affects the generation of large crustal earthquakes and mountain buildings.

show abstract

“…An increasing number of seismic tomography studies aimed at providing a detailed structure of the Greenland mantle and crust have been conducted in the past several years (e.g., Antonijevic & Lees, 2018; Mordret, 2018; Pourpoint et al., 2018; Toyokuni & Zhao, 2021; Toyokuni et al., 2020). The common feature revealed by most of these tomography studies is an elongated zone with lower‐velocity anomalies and a relatively thin lithosphere spanning from the west to the east coasts of central Greenland, even though its direction and spatial and depth extents are debated (Celli et al., 2021; Lebedev et al., 2018; Mordret, 2018; Rickers et al., 2013; Toyokuni & Zhao, 2021; Toyokuni et al., 2020). This elongated zone has been proposed to be associated with the trajectory of the Iceland hotspot as the Greenland continent drifted over a mantle plume (Lebedev et al., 2018; Mordret, 2018; Pourpoint et al., 2018; Rickers et al., 2013; Toyokuni et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

A Tilted Broad Plume Underneath the Greenland Cratonic Keels

Wang,

Gao,

Liao

et al. 2024

Geophysical Research Letters

View full text Add to dashboard Cite

To advance our comprehension of the complex geological history and mantle dynamics in the North Atlantic region, we employ all available broadband seismic data recorded in Greenland to reveal an abnormal mantle transition zone (MTZ) structure. Central and eastern Greenland exhibits depressed 410 and 660 km discontinuities (d410 and d660, respectively) bordering the MTZ, indicative of a substantial thermal anomaly associated with an underlying plume, surpassing the 1,800°C threshold for post‐garnet phase transitions at the d660. Variations in MTZ thickness across Greenland stem from differing temperature anomalies at the d410 and d660, possibly linked to a tilted plume within the MTZ. These findings corroborate geodynamic models, elucidating the interaction between post‐garnet phase transitions and upwelling plumes. The results shed light on the origin of the enigmatic Icelandic hotspot track and its influence on the thermal and lithospheric structures beneath Greenland.

show abstract

P‐Wave Tomography for 3‐D Radial and Azimuthal Anisotropy Beneath Greenland and Surrounding Regions

Cited by 5 publications

References 65 publications

2D Near‐Surface Full‐Waveform Tomography Reveals Bedrock Controls on Critical Zone Architecture

2D Near‐Surface Full‐Waveform Tomography Reveals Bedrock Controls on Critical Zone Architecture

Seismic Anisotropy Tomography and Mantle Dynamics

A Tilted Broad Plume Underneath the Greenland Cratonic Keels

Contact Info

Product

Resources

About