KAMEYAMA Masanori

A series of our linear analysis on the onset of thermal convection was applied to that of highly compressible fluids in a planar layer whose thermal conductivity and viscosity vary in space, in order to study the influences of spatial variations i...

Numerical models of bottom-heated thermal convection of highly compressible fluid with strongly temperature-dependent viscosity are presented to understand how the Rayleigh number Ra and the temperature dependence of viscosity exert control over t...

The influence of MgSiO<inf>3</inf> majorite on mantle convection has been investigated via 2-D numerical simulations that incorporate the stability field of majorite. According to a recent first principles study, wadsleyite decomposes into an asse...

To understand how adiabatic compression influences mantle convection in super-Earths, we carried out linear stability analysis and non-linear numerical simulation of thermal convection for constant viscosity infinite Prandtl number fluid with both...

Numerical models are presented to clarify how adiabatic compression affects thermal convection in the mantle of super-Earths ten times the Earth's mass. The viscosity strongly depends on temperature, and the Rayleigh number is much higher than tha...

A series of linear stability analysis is carried out on the onset of thermal convection in the presence of spatial variations of viscosity, thermal conductivity and expansivity. We consider the temporal evolution of an infinitesimal perturbation s...

We examined in an analytical manner the stability of thermal stratification of highly compressible fluids with depth-dependent physical properties, to obtain the fundamental insights into the convective motion in the mantles of 'super-Earths'. We ...

Geological studies have suggested that a significant amount of crustal material has been lost from the surface due to delamination, continental collision, and subduction at oceanic-continental convergent margins. If so, then the subducted crustal ...

In this paper we carried out numerical experiments of a time-dependent thermal convection in a two-dimensional Cartesian box of aspect ratio (width/height) of 6, in order to study the influences on the convecting flow patterns of the spatial varia...

Geological studies have revealed that continental materials subduct from the Earth's surface via the following three mechanisms: tectonic erosion, sediment subduction, and direct subduction of immature oceanic arcs. Then, the continental materials...

A linear stability analysis was performed in order to study the onset of thermal convection in the presence of a strong viscosity variation, with a special emphasis on the condition for the stagnant-lid (ST) convection where a convection takes pla...

We conducted two-dimensional numerical experiments of mantle convection with imposed kinematic motions of cold slabs, in order to study the mechanism for the generation of ascending flows in the "Big Mantle Wedge" (BMW), which has been recently pr...

During an earthquake, fault strength decreases with slip over the slip-weakening distance, Dc, to a residual strength. The estimation of Dc is crucial for the evaluation of fault instability during earthquakes; however, it has been difficult to de...

Benchmark comparisons are an essential tool to verify the accuracy and validity of computational approaches to mantle convection. Six 2-D Cartesian compressible convection codes are compared for steady-state constant and temperature-dependent visc...

In this study, we propose a so-called fluid rope coiling to use as a validity test of our simulation scheme designed to solve the plate-mantle problem in the Eulerian frame of reference. In a plate-mantle unified system, a subducting plate is know...

A new simulation code of mantle convection in a three-dimensional spherical shell is presented. Major innovation of the code comes from an combination of two numerical techniques, namely Yin-Yang grid and ACuTE algorithm, which we had developed fo...

We have developed a new strategy and espouse a novel paradigm for large-scale computing and real-time interactive visualization. This philosophy calls for intense interactive sessions for a couple of hours at a time at the expense of storing data ...

Toward the unified simulation of the large deformation of a rigid viscoelastic material (plate) and the convection of a viscous fluid (mantle), an Eulerian scheme with a semi-Lagrangian method is developed. The scheme adopts the CIP-CSLR method fo...

The current availability of thousands of processors at many high performance computing centers has made it feasible to carry out, in near real time, interactive visualization of 3D mantle convection temperature fields, using grid configurations ha...

Superplumes in the lower mantle have been inferred for a long time by the presence of two very large provinces with slow seismic wave velocities. These extensive structures are not expected from numerical and laboratory experiments nor are they fo...

Burial depth, cumulative displacement, and peak temperature of frictional heat of a fault system are estimated by thermal analysis in the fold-thrust belt of the Western Foothills complex, western Taiwan based on the vitrinite reflectance techniqu...

We have developed a two-dimensional dynamical model of asymmetric subduction integrated into the mantle convection without imposed plate velocities. In this model we consider that weak oceanic crust behaves as a lubricator on the thrust fault at t...

The discovery of post-perovskite phase transition near the core-mantle boundary(CMB) has turned our heads to the potentially important role played by the increasing complexity of the physical properties in the lower-mantle models. In this study we...

The influences of the post-perovskite (PPV) phase transition on the thermal state in the lower mantle are studied with a three-dimensional model of mantle convection in a Cartesian domain under the extended Boussinesq approximation with variable v...

A numerical algorithm for solving mantle convection problems with strongly variable viscosity is presented. Equations for conservation of mass and momentum for highly viscous and incompressible fluids are solved iteratively by a multigrid method i...

For realistic geodynamo simulations, one must solve the magnetohydrodynamic equations to follow time development of thermal convection motion of electrically conducting fluid in a rotating spherical shell. We have developed a new geodynamo simulat...

We investigated the similarity between thermal-viscous coupling (TVC) and frictional sliding, proposed by Kameyama and Kaneda [Pure Appl. Geophys. 159 (2002) 2011]. We consider a one-dimensional layer composed of viscous material, which is sandwic...

We propose a thermal-mechanical model of shear deformation of a viscoelastic material to describe the temperature-dependence of friction law. We consider shear deformation of one-dimensional layer composed of a Maxwell linear viscoelastic material...

We develop a thermal-mechanical model for describing the formation of shear zones. We consider shear deformation of a two-dimensional rectangular region composed of a viscous fluid under a constant velocity at the boundary. Viscosity of the materi...

We studied for the first time the effects of low-temperature plasticity on the formation of shear zones. A thermal-mechanical model has been developed for describing the shear deformation of Maxwell viscoelastic material with a rheology close to d...

The formation of localized shear zones is important for understanding many local and global processes in geodynamics. We have developed a self-consistent thermal-mechanical model together with a rheology which depends on temperature, strain-rate a...

A numerical model of mantle magmatism in a convecting upper mantle has been developed to study the thermo-chemical evolution of the upper mantle of the early Earth. The solid-state convection in the upper mantle is modeled by a convection of a bin...