We identify two interrelated but independent species of microcracks with differentorigins and different distributions. One species is the classic high-stress microcracksidentified in laboratory stress-cells associated...We identify two interrelated but independent species of microcracks with differentorigins and different distributions. One species is the classic high-stress microcracksidentified in laboratory stress-cells associated with acoustic emissions as microcracks openwith increasing stress. The other species is the low-stress distributions of closely-spacedstress-aligned fluid-saturated microcracks that observations of shear-wave splitting （SWS）demonstrate pervade almost all in situ rocks in the upper crust, the lower crust, and theuppermost 400 km of the mantle. On some occasions these two sets of microcracks may beinterrelated and similar （hence ＇species＇） but they typically have fundamentally-differentproperties, different distributions, and different implications. The importance for hydrocarbonexploration and recovery is that SWS in hydrocarbon reservoirs monitors crack alignmentsand preferred directions of fluid-flow. The importance for earthquake seismology is that SWSabove small earthquakes monitors the effects of increasing stress on the pervasive low-stressmicrocrack distributions so that stress-accumulation before, possibly distant, earthquakes canbe recognised and impendin~ earthquakes stress-forecast.展开更多
In the last decade a New Geophysics has been proposed,whereby the crust and uppermost ~400 km of the mantle of the Earth are so pervaded by closely-spaced stress-aligned microcracks(intergranular films of hydrated mel...In the last decade a New Geophysics has been proposed,whereby the crust and uppermost ~400 km of the mantle of the Earth are so pervaded by closely-spaced stress-aligned microcracks(intergranular films of hydrated melt in the mantle) that in situ rocks verge on failure by fracturing,and hence are critical-systems that impose a range of fundamentally-new properties on conventional sub-critical geophysics.Enough of these new properties have been observed to confirm that New Geophysics is a new understanding of fluid/rock deformation with important implications and applications.Evidence supporting New Geophysics has been published in a wide variety of publications.Here,for clarification,we summarise in one document the evidence supporting New Geophysics.展开更多
This paper reviews a new understanding of shear-wave splitting （seismic-birefringence） that is a fundamental revision of conventional fluid-rock deformation. It is a New Geophysics with implications for almost all s...This paper reviews a new understanding of shear-wave splitting （seismic-birefringence） that is a fundamental revision of conventional fluid-rock deformation. It is a New Geophysics with implications for almost all solid-earth geosciences, including hydrocarbon exploration and production, and earthquake forecasting. Widespread observations of shear-wave splitting show that deformation in in situ rocks is controlled by stress-aligned fluid-saturated grain-boundary cracks and preferentially orientated pores and pore-throats pervasive in almost all igneous, metamorphic, and sedimentary rocks in the Earth＇s crust. These fluid-saturated microcracks are the most compliant elements of the rock-mass and control rock deformation. The degree of splitting shows that the microcracks in almost all rocks are so closely spaced that they verge on fracture-criticality and failure by fracturing, and are critical systems with the “butterfly wing＇s” sensitivity of all critical systems. As a result of this crack-criticality, evolution of fluid-saturated stress-aligned microcracked rock under changing conditions can be modelled with anisotropic poroelasticity （APE）. Consequently, low-level deformation can be： monitored with shear-wave splitting; future behaviour calculated with APE; future behaviour predicted with APE, if the change in conditions can be quantified; and in principle, future behaviour controlled by feed-back. This paper reviews our current understanding of the New Geophysics of low-level pre-fracturing deformation.展开更多
The linear Gutenberg-Richter relationship is well-established. In any region of the Earth, the logarithm of the number of earthquakes, greater than any magnitude, is proportional to magnitude. This means that the unde...The linear Gutenberg-Richter relationship is well-established. In any region of the Earth, the logarithm of the number of earthquakes, greater than any magnitude, is proportional to magnitude. This means that the underlying physics is non-linear and not purely elastic. This nonlinear physics has not been resolved. Here we suggest that a new understanding of fluid-rock deformation provides the physics underlying Gutenberg-Richter： where the fluid-saturated microcracks in almost all in situ rocks are so closely-spaced that they verge on failure and fracture, and hence are critical-systems which impose fundamentally-new properties on conventional sub-critical geophysics. The observation of linear Gutenberg-Richter relationship in moonquakes suggests that residual fluids exist at depth in the Moon.展开更多
基金This study was partially supported by the National Natural Science Foundation of China （No. 41174042）.
文摘We identify two interrelated but independent species of microcracks with differentorigins and different distributions. One species is the classic high-stress microcracksidentified in laboratory stress-cells associated with acoustic emissions as microcracks openwith increasing stress. The other species is the low-stress distributions of closely-spacedstress-aligned fluid-saturated microcracks that observations of shear-wave splitting （SWS）demonstrate pervade almost all in situ rocks in the upper crust, the lower crust, and theuppermost 400 km of the mantle. On some occasions these two sets of microcracks may beinterrelated and similar （hence ＇species＇） but they typically have fundamentally-differentproperties, different distributions, and different implications. The importance for hydrocarbonexploration and recovery is that SWS in hydrocarbon reservoirs monitors crack alignmentsand preferred directions of fluid-flow. The importance for earthquake seismology is that SWSabove small earthquakes monitors the effects of increasing stress on the pervasive low-stressmicrocrack distributions so that stress-accumulation before, possibly distant, earthquakes canbe recognised and impendin~ earthquakes stress-forecast.
文摘In the last decade a New Geophysics has been proposed,whereby the crust and uppermost ~400 km of the mantle of the Earth are so pervaded by closely-spaced stress-aligned microcracks(intergranular films of hydrated melt in the mantle) that in situ rocks verge on failure by fracturing,and hence are critical-systems that impose a range of fundamentally-new properties on conventional sub-critical geophysics.Enough of these new properties have been observed to confirm that New Geophysics is a new understanding of fluid/rock deformation with important implications and applications.Evidence supporting New Geophysics has been published in a wide variety of publications.Here,for clarification,we summarise in one document the evidence supporting New Geophysics.
文摘This paper reviews a new understanding of shear-wave splitting （seismic-birefringence） that is a fundamental revision of conventional fluid-rock deformation. It is a New Geophysics with implications for almost all solid-earth geosciences, including hydrocarbon exploration and production, and earthquake forecasting. Widespread observations of shear-wave splitting show that deformation in in situ rocks is controlled by stress-aligned fluid-saturated grain-boundary cracks and preferentially orientated pores and pore-throats pervasive in almost all igneous, metamorphic, and sedimentary rocks in the Earth＇s crust. These fluid-saturated microcracks are the most compliant elements of the rock-mass and control rock deformation. The degree of splitting shows that the microcracks in almost all rocks are so closely spaced that they verge on fracture-criticality and failure by fracturing, and are critical systems with the “butterfly wing＇s” sensitivity of all critical systems. As a result of this crack-criticality, evolution of fluid-saturated stress-aligned microcracked rock under changing conditions can be modelled with anisotropic poroelasticity （APE）. Consequently, low-level deformation can be： monitored with shear-wave splitting; future behaviour calculated with APE; future behaviour predicted with APE, if the change in conditions can be quantified; and in principle, future behaviour controlled by feed-back. This paper reviews our current understanding of the New Geophysics of low-level pre-fracturing deformation.
文摘The linear Gutenberg-Richter relationship is well-established. In any region of the Earth, the logarithm of the number of earthquakes, greater than any magnitude, is proportional to magnitude. This means that the underlying physics is non-linear and not purely elastic. This nonlinear physics has not been resolved. Here we suggest that a new understanding of fluid-rock deformation provides the physics underlying Gutenberg-Richter： where the fluid-saturated microcracks in almost all in situ rocks are so closely-spaced that they verge on failure and fracture, and hence are critical-systems which impose fundamentally-new properties on conventional sub-critical geophysics. The observation of linear Gutenberg-Richter relationship in moonquakes suggests that residual fluids exist at depth in the Moon.
