Masaki Yoshida

Ritsumeikan University

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Claudia Adam

Kansas State University

Satoru Honda

The University of Tokyo

Fumiko Tajima

University of California, Irvine

Pedro Madureira

Estrutura de Missão para a Extensão da Plataforma Continental

M. Santosh

University of Adelaide

Yoshio Fukao

Japan Agency for Marine-Earth Science and Technology

Daisuke Suetsugu

Japan Agency for Marine-Earth Science and Technology

Tomoeki Nakakuki

Hiroshima University

Ken‐ichi Hirauchi

Shizuoka University

J. M. Miranda

Instituto Dom Luiz

Cooperative Institutions

Japan Agency for Marine-Earth Science and Technology

The University of Tokyo

Association for the Development of Earthquake Prediction

Hiroshima University

Earthquake Engineering Research Institute

Centre National de la Recherche Scientifique

Tokyo Institute of Technology

Kyoto University

Tohoku University

Planetary Science Institute

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Large-scale structures in the Earth’s interior: Top-down hemispherical dynamics constrained by geochemical and geophysical approaches

Frontiers in Earth Science (2022)

Hikaru Iwamori Masaki Yoshida Hitomi Nakamura

Geochemical and geophysical observations for large-scale structures in the Earth’s interior, particularly horizontal variations of long wavelengths such as degree-1 and degree-2 structures, are reviewed with special attention to the cause of hemispherical mantle structure. Seismic velocity, electrical conductivity, and basalt geochemistry are used for mapping the large-scale structures to discuss thermal and compositional heterogeneities and their relations to dynamics of the Earth’s interior. Seismic velocity structure is the major source of information on the Earth’s interior and provides the best spatial resolution, while electrical conductivity is sensitive to water/hydrogen contents. The composition of young basalts reflects the mantle composition, and the formation age of large-scale structures can be inferred based on the radiogenic isotopes. Thus, these different research disciplines and methods complement each other and can be combined to more concretely constrain the structures and their origins. This paper aims to integrate observations from these different approaches to obtain a better understanding of geodynamics. Together with numerical modeling results of convection in the mantle and the core, “top-down hemispherical dynamics” model of the crust-mantle-core system is examined. The results suggest that a top-down link between the supercontinents, mantle geochemical hemisphere, and inner core seismic velocity hemisphere played an essential role in formation of the large-scale structures and dynamics of the Earth’s interior.

geodynamics

Core–mantle boundary

Radiogenic nuclide

10.3389/feart.2022.1033378

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Citations (1)

Core‐mantle boundary topography estimated from numerical simulations of instantaneous mantle flow

Geochemistry Geophysics Geosystems (2008)

Masaki Yoshida

Core‐mantle boundary (CMB) topography is estimated from numerical simulations of instantaneous mantle flow in a three‐dimensional spherical shell geometry. Density anomaly models of the Earth's mantle are derived from geodynamic models constrained principally by seismic tomography results. To account for the small (±∼1.5 km) CMB topographic relief inferred from recent seismological results, lateral viscosity variations in the mantle, compositionally dense piles in the deep mantle, and a low‐viscosity D″ layer are all required for the numerical models. Low‐viscosity subducting slabs in the lower mantle serve to reduce the topographic amplitude below high‐velocity regions (i.e., the circum‐Pacific belt). The existence of dense piles may cause the local topographic depressions even below low‐velocity regions (i.e., the South Pacific and Atlantic Africa regions).

Core–mantle boundary

Seismic Tomography

Hotspot (geology)

10.1029/2008gc002008

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Citations (47)

Where and why do large shallow intraslab earthquakes occur?

Physics of The Earth and Planetary Interiors (2004)

Tetsuzo Seno Masaki Yoshida

Slab

Focal mechanism

Clockwise

10.1016/j.pepi.2003.11.002

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Citations (28)

Corrigendum to “Mantle dynamics and characteristics of the Azores plateau” [Earth Planet. Sci. Lett. 362 (2013) 258—271]

Earth and Planetary Science Letters (2015)

Claudia Adam Pedro Madureira J. M. Miranda N. Lourenço Masaki Yoshida

10.1016/j.epsl.2015.07.045

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Citations (0)

Dynamic conditions for large shallow intraslab earthquakes: four categories of subduction zones

Geoscience Letters (2024)

Masaki Yoshida

Abstract Large shallow intraslab earthquakes (LSIEs) of over magnitude-7 rarely occur at shallower depths (≤ 60 km) in the subducting plates of the circum-Pacific and northern margin of the Australian Plate off Indonesia. Previous studies have suggested that most LSIEs occur under surface tectonic conditions with a lateral stress gradient across the back-arc to the fore-arc on the overriding plate based on seismological and geological evidence. In this study, dynamic conditions for the occurrence of LSIEs were studied using the intraslab stress state, stress state of the overriding plate, motion speed of overriding and subducting plates, and trench migration speed determined by plate motion models. LSIEs prefer tectonic conditions under (1) an extensional-to-neutral stress state in the back-arc, (2) a compressional stress state in the fore-arc, and (3) down-dip tension in the shallower part of the subducting plate. The results suggest that the Earth’s subduction zones can be classified into four categories. This categorization is informed by the behavior of underlying mantle flow, i.e., the magnitude of slab suction flow in the mantle under the subducting plates, which is related to the degree of plate-slab coupling, and the scale of return flow in the mantle wedge under the overriding plates, which varies the combination of stress states in the fore-arc and back-arc.

10.1186/s40562-024-00361-7

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Seafloor subsidence and mantle dynamics

Japan Geoscience Union (2016)

Claudia Adam Scott D. King M. Rabinowicz Valérie Vidal A. Jalobeanu

Seafloor Spreading

Hotspot (geology)

Source

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On mantle drag force for the formation of a next supercontinent as estimated from a numerical simulation model of global mantle convection

Terra Nova (2019)

Masaki Yoshida

Abstract Three‐dimensional spherical mantle convection was simulated to predict future continental motion and investigate the driving force of continental motion. Results show that both the time required (≥300 Ma from the present) and the process for the next supercontinent formation are sensitive to the choice of critical rheological parameters for mantle dynamics, such as a viscosity contrast between the upper and lower mantles and a yield strength of the lithosphere. From all the numerical models studied herein, mantle drag force by horizontal mantle flow beneath the continents may mostly act as a resistance force for the continental motion in the process of forming a new supercontinent. The maximum absolute magnitude of the tensional and compressional stress acting at the base of the moving continents is in the order of 100 MPa, which is comparable to a typical value of the slab pull force.

Supercontinent

Slab

10.1111/ter.12380

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Citations (6)

Effect of the supercontinent cycle on the longest-term sea-level change from a simple conceptual and theoretical model

Gondwana Research (2023)

Masaki Yoshida

Supercontinent

Continental drift

10.1016/j.gr.2023.06.015

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