A shear failure strength law of rock in the brittle‐plastic transition regime

Ohnaka, Mitiyasu

doi:10.1029/94gl02791

Cited by 99 publications

(70 citation statements)

References 22 publications

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“…From laboratory experiments, we have γ = 0.01-0.02, c 0 = 100-140 MPa, and c 1 = 0.7-0.75 for the shear fracture of intact granite (Masuda et al, 1987;Kato et al, 2003a, b;Ohnaka, 1995). We thus find that the rate effect expressed by Eq.…”

Section: Constitutive Formulation For Earthquake Rupturesmentioning

confidence: 73%

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Earthquake cycles and physical modeling of the process leading up to a large earthquake

Ohnaka

2014

Earth Planet Sp

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A thorough discussion is made on what the rational constitutive law for earthquake ruptures ought to be from the standpoint of the physics of rock friction and fracture on the basis of solid facts observed in the laboratory. From this standpoint, it is concluded that the constitutive law should be a slip-dependent law with parameters that may depend on slip rate or time. With the long-term goal of establishing a rational methodology of forecasting large earthquakes, the entire process of one cycle for a typical, large earthquake is modeled, and a comprehensive scenario that unifies individual models for intermediate-and short-term (immediate) forecasts is presented within the framework based on the slip-dependent constitutive law and the earthquake cycle model. The earthquake cycle includes the phase of accumulation of elastic strain energy with tectonic loading (phase II), and the phase of rupture nucleation at the critical stage where an adequate amount of the elastic strain energy has been stored (phase III). Phase II plays a critical role in physical modeling of intermediate-term forecasting, and phase III in physical modeling of short-term (immediate) forecasting. The seismogenic layer and individual faults therein are inhomogeneous, and some of the physical quantities inherent in earthquake ruptures exhibit scale-dependence. It is therefore critically important to incorporate the properties of inhomogeneity and physical scaling, in order to construct realistic, unified scenarios with predictive capability. The scenario presented may be significant and useful as a necessary first step for establishing the methodology for forecasting large earthquakes.

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Section: Constitutive Formulation For Earthquake Rupturesmentioning

confidence: 73%

“…The functional form g(σ eff n ) is expressed as a linear function of σ eff n as follows (see Ohnaka, 1995):…”

Section: Constitutive Formulation For Earthquake Rupturesmentioning

confidence: 99%

Earthquake cycles and physical modeling of the process leading up to a large earthquake

Ohnaka

2014

Earth Planet Sp

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“…Here we assumed K ref = 3.05 W m −1 K −1 is the thermal conductivity of the Putulsk meteorite for a temperature T ref = 300 K. The tensile strength value, for which we did not find a direct temperature-dependence measurements, was approximated with the temperature dependence for the shear strength (Rocchi et al 2004;Ohnaka 1995) …”

Section: Ordinary Chondrite (Group I) Materialsmentioning

confidence: 99%

“…We adopt Q/R g = 1100 K and T 1 = 2500 K given by Ohnaka (1995). The constant σ t0 was assumed to correspond to the measured value of the Putulsk meteorite, namely σ t0 = −32 MPa.…”

Section: Ordinary Chondrite (Group I) Materialsmentioning

confidence: 99%

Thermal stresses in small meteoroids

Čapek

Vokrouhlický

2010

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Aims. We evaluate thermal stresses in small, spherical, and homogeneous meteoroids with elastic rheology and regular rotation. The temperature variations are caused by the absorbed sunlight energy being conducted into the interior layers of the body. Our model assumes arbitrary thermal conductivity value, but restricts itself to a linearized treatment of the boundary conditions of the heat diffusion problem. We consider the diurnal insolation cycle only as if the body were in a fixed position along its heliocentric orbit. This constrains the upper limit to the object size to which our modeling is applicable. Methods. We derive analytical expressions for the components of the thermal stress tensor throughout the body. Using two sets of material properties (ordinary and carbonaceous chondrites), we study the conditions required for material failure caused by thermal stress leading to fission. Results. Our results indicate that the onset of thermal failure in the meteoroid depends on a number of parameters including the heliocentric distance, the size, the rotation frequency, and the orientation of the spin axis with respect to the solar direction. In our case, we find large, centimeter-to meter-size, slowly rotating meteoroids or those with a spin axis pointing towards the Sun or both, are the most susceptible to the thermal bursting. This may have implications for the (i) size distribution of meteoroids in various streams depending on their heliocentric orbit and the physical characteristics of their parent bodies; (ii) orbital distribution of sporadic complexes of meteoroids in the planet-crossing zone; and/or (iii) fate of fragments released during comet disintegration events, especially those with low perihelia (e.g., Kreutz class).

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“…This relation is often called "Byerlee's law" and holds over a wide range of pressures, temperatures and compositions (Byerlee 1978), so long as the rock is actually solid. At high temperatures this coefficient declines as the rock softens (Stesky et al 1974, Ohnaka 1995.…”

Section: Frictional Heating Of Rocksmentioning

confidence: 99%

The Mechanics of Pseudotachylite Formation in Impact Events

Melosh

Impact Studies

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This paper presents a discussion of the basic constraints controlling the formation of pseudotachylites in the rapidly sheared rocks in the vicinity of a large meteorite impact. The prevailing opinion among many geologists is that pseudotachylites are formed by friction melting of rock. The principal mystery of pseudotachylite formation is not that friction can cause melting, but that it seems to form thick masses of it. Yet such thick masses ought to preclude melting by reducing the friction between sliding rock masses. I propose that one possible solution to this conundrum is that the melt produced by sliding on narrow shear zones is extruded into the adjacent country rock, thus keeping the sliding surfaces narrow.3

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A shear failure strength law of rock in the brittle‐plastic transition regime

Cited by 99 publications

References 22 publications

Earthquake cycles and physical modeling of the process leading up to a large earthquake

Earthquake cycles and physical modeling of the process leading up to a large earthquake

Thermal stresses in small meteoroids

The Mechanics of Pseudotachylite Formation in Impact Events

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