Heat flow from the earth’s interior depending on inner parameters variations

The approximate equality of heat flows on the land and the ocean; high heat flow values on the middle oceanic ridges; a relationship of heat flow with age of tectogenesis; the extremely low heat flow values are considered as main evidence for any theoretical explanation. The deviation of surface heat flow from its equilibrium value is considered. Computing analysis of high temperature heat transfer coefficients is given. Some aspects of numerical techniques of the thermal history of the Earth are discussed. The influence of sudden and gradual formation of the Earth Crust on the surface heat flow is considered.     

Groundwater flow and storage processes in an inactive rock glacier

Groundwater flow through coarse blocky landforms contributes to streamflow in mountain watersheds, yet its role in the alpine hydrologic cycle has received relatively little attention. This study examines the internal structure and hydrogeological characteristics of an inactive rock glacier in the Canadian Rockies using geophysical imaging techniques, analysis of the discharge hydrograph of the spring draining the rock glacier, and chemical and stable isotopic compositions of source waters. The results show that the coarse blocky sediments forming the rock glacier allow the rapid infiltration of snowmelt and rain water to an unconfined aquifer above the bedrock surface. The water flowing through the aquifer is eventually routed via an internal channel parallel to the front of the rock glacier to a spring, which provides baseflow to a headwater stream designated as a critical habitat for an at‐risk cold‐water fish species. Discharge from the rock glacier spring contributes up to 50% of basin streamflow during summer baseflow periods and up to 100% of basin streamflow over winter, despite draining less than 20% of the watershed area. The rock glacier contains patches of ground ice even though it may have been inactive for thousands of years, suggesting the resiliency of the ground thermal regime under a warming climate.     

Wave trapping and flow around an irregular near circular island in a stratified sea

Wave trapping and induced flow around an island is examined. The exactly circular island solutions are reprised and the solutions extended, and shown to apply to a stratified sea. The homogeneous solutions are then used to deduce the wave trapping and flow around a near circular island. It turns out that the cotidal pattern for a perfectly circular island is relatively immune to variations in geometry and radially dependent depth variations. This helps explain the similarity in the behaviour of the tides around various islands (the Pribilof Islands near Alaska, Oahu in Hawaii, Cook Island off north west Australia, Bermuda off the eastern coast of the USA, and Bear Island in the Norwegian Sea). The dominant steady drift and its rate of decay off-shore is also calculated.     

TheQ value variations in the preparing process of rock rupture

In this paper, the "spectral amplitude ratio method" (SAR), "energy method" (EN) and "coda wave method" (CW) are used to calculate theQ value variations of gneiss in the preparing rupture process. The obtained results show that the variation state ofQ values by SAR features the shape of relative stability—gradual increment to the maximum—then decrement and final rupture. The variation state ofQ values by EN is just contrary to that by SAR, i. e. with the shape of stability—decrement—increment—and final rupture. The varation state ofQ values by CW is similar to that by EN, its main frequency features the shape of relatively high value—decrement to the minimum—increment—and final rupture. But to the high frequency (higher than the main frequency), the variation state ofQ values features the shape of the stable value-increment to the maximum-decrement-and final rupture. At the same time, the results by coda wave amplitude spectrum show that, when stress reaches 70% of rupture stress, the high frequency component of S wave rapidly reduces (Q _c increasing); at the time of impending the main rupture, the main frequency component reduces with a large scale (Q _c increasing again), this may be the reason which causes the different variation states of two codaQ values. The result of amplitude spectra of P, S (initial wave) waves also show that with the appearance of microcracks the frequency band of S wave turn to be narrow, the high frequency component is reduced quickly, i. e. the S wave spectra have different variation states with different frequency components. That is why theQ _s obtained by different methods have different variation characteristics.     

Heat transfer between a thermochemical plume channel and the surrounding mantle in the presence of horizontal mantle flow

Heat and mass transfer processes in the conduit of a thermochemical plume located beneath an oceanic plate far from a mid-ocean ridge (MOR) proceed under conditions of horizontal convective flows penetrating the plume conduit. In the region of a mantle flow approaching the plume conduit (in the frontal part of the conduit), the mantle material heats and melts. The melt moves through the plume conduit at the average velocity of flow v and is crystallized on the opposite side of the conduit (in the frontal part of the conduit). The heat and the chemical dope transferred by the conduit to the mantle flow are carried away by crystallized mantle material at the velocity v.The local coefficients of heat transfer at the boundary of the plume conduit are theoretically determined and the balance of heat fluxes through the side of the plume conduit per linear meter of the conduit height. The total heat generation rate, transmitted by the Hawaiian plume into the upper and lower mantle, is evaluated. With the use of regular patterns of heat transfer in the lower mantle, which is modeled on the horizontal layer, heated from below and cooled from above, the diameter of the plume source, the kinematic viscosity of the melt in the plume conduit, and the velocity of horizontal lower-mantle flows are evaluated and the dependences of the temperature drop, viscosity and Rayleigh number for the lower mantle on the diameter of the plume source are presented.     

The Q value variations in the preparing pro－cess of rock rupture

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Heat flow in Italy

More than fifty heat flow measurements in Italy are examined. The values, corrected only for local influences (when present), are related to the main geological features with the following results: foreland areas, 55±19 mW m^–2, foredeep areas, 45±21 mW m^–2; folded regions and intermountain depressions, 76±29 mW m^–2. In volcanic areas the heat flow rises to in excess of 600 mW m^–2. From a tectonic point of view, these values are consistent with the hypothesis that the Apennine chain is intersected by two arcuate structures: the first from Liguria to Latium is very probably a continental arc, that is an are which occurs within a continent, and the second from Campania to Calabria is very similar from geophysical evidence to the classic island arcs.     

On geophysical explanation of some irregular variations of the mean latitudes of latitude stations

Mean latitude variations computed by Orlovs or other filters have some irregular variations in addition to secular ones. These are of the order of ±0.05 to ±0.1, they can last several years and sometimes show regional similarities. In looking for an explanation of such latitude variations several physical mechanisms have been investigated. The most probable one is the mechanism of stress propagation in the lithosphere and asthenosphere. The consequent gravitational and deformational effects could explain both the magnitude and the time dependance of the irregular latitude variations.     

Waves in an elastic plate with an irregular boundary

Summary Green's function corresponding to the displacements for anSH-line source inside a wedge shaped medium finite or infinite in which the density and the elastic parameter are not constant throughout but some class of function ofr, the radial distance (i.e. and satisfy some differential equation) has been obtained. The paths of propagation of the cylindrical waves, their reflections on different boundaries and their continuous refractions within the medium has been clearly established. The scattered field from the different parts of the body have been pointed out with prescribed distribution of and in this inhomogeneous wedge. It is shown that for some distribution of and the rays are curved and the reflections at the two plane boundaries occur in such a way that no ray will go to infinity by reflection, rather they are coming back towards the apex after suitable number of reflections with variable intensity. Also there are some distributions of and in the same class as mentioned earlier, such that the behaviour of the waves is similar to that in a homogeneous wedge, i.e. these waves will go to infinity by a suitable number of reflections and ultimately die out. The first case is quite unlike the usual homogeneous medium with non parallel boundaries and so care must be taken in computing the field within the nonhomogeneous medium within the non-parallel boundaries.     

Heat flow in the southwestern Okinawa Trough

Lying to the southeast of the East China Sea continental shelf, the Okinawa Trough is believed to have been formed by crustal spreading behind the Ryukyu island arc. It has the highest mean heat flow among the Pacific marginal basins. The mean of 18 reliable measurements is3.34±2.75HFU. The next highest mean heat flow for a marginal basin is2.53±1.60HFU for the Fiji Plateau. The high mean value for the Okinawa Trough may be partially attributable to a sampling bias because most measurements were made in or near the well-sedimented central “rift” or graben. The reported values range from 0.36 to 10.49 HFU, with low values probably resulting from hydrothermal circulation in an area of large relief. The high heat flow suggests that the age of the Okinawa Trough may be as young as 2 Ma. Such an estimate is in gross agreement with the inferred Plio-Pleistocene age for the drifting in the Okinawa Trough. The opening of the Okinawa Trough may continue onto Taiwan but the relation between the opening of the trough and the occurrence of a nearby, onshore geothermal resource area remains unsolved.     

The Q value variations in the preparing process of rock rupture

In this paper, the "spectral amplitude ratio method" (SAR), "energy method" (EN) and "coda wave method" (CW) are used to calculate theQ value variations of gneiss in the preparing rupture process. The obtained results show that the variation state ofQ values by SAR features the shape of relative stability—gradual increment to the maximum—then decrement and final rupture. The variation state ofQ values by EN is just contrary to that by SAR, i. e. with the shape of stability—decrement—increment—and final rupture. The varation state ofQ values by CW is similar to that by EN, its main frequency features the shape of relatively high value—decrement to the minimum—increment—and final rupture. But to the high frequency (higher than the main frequency), the variation state ofQ values features the shape of the stable value-increment to the maximum-decrement-and final rupture. At the same time, the results by coda wave amplitude spectrum show that, when stress reaches 70% of rupture stress, the high frequency component of S wave rapidly reduces (Q _c increasing); at the time of impending the main rupture, the main frequency component reduces with a large scale (Q _c increasing again), this may be the reason which causes the different variation states of two codaQ values. The result of amplitude spectra of P, S (initial wave) waves also show that with the appearance of microcracks the frequency band of S wave turn to be narrow, the high frequency component is reduced quickly, i. e. the S wave spectra have different variation states with different frequency components. That is why theQ _s obtained by different methods have different variation characteristics.     

Heat flow on the Pacific-Antarctic Ridge

Twenty-four heat flow measurements are clustered in 5–20 m.y. and 60–80 m.y. old seafloor on the crest and northern flank of the Pacific-Antarctic Ridge. The crestal heat flow stations are characterized by (1) low mean heat flow relative to that predicted by theoretical models, (2) thin sediment cover, and (3) high ratio of standard deviation to mean heat flow, all of which indicate a system dominated by convective heat transfer. The measurements made on older seafloor of the northern flank have (1) mean heat flow equal to the theoretical predictions of conductively-cooling lithospheric plate models, (2) thick sediment cover, and (3) low ratio of standard deviation to mean heat flow. Thus convective loss associated with hydrothermal circulation is not considered to be important in 60–80 m.y. old seafloor on the Pacific-Antarctic Ridge. The pattern of heat flow on this ridge is thus similar to that in the Atlantic, Indian and Pacific Oceans: hydrothermal circulation is dominant on the ridge crest but is suppressed on the flanks, possibly due to a difference in the hydraulic admittance of the sediment between the two regions.     

Heat flow in the Upper Silesian coal basin

Summary The paper presents results of heat flow measurements made in 6 deep bores in the Czechoslovakian part of the Upper Silesian coal basin. The heat flow measured was in the range from 1.74 to 1.87 cal/cm²s. The undisturbed period before the temperature measurement in the bore is discussed and results of repeated temperature measurements carried out 0.1, 1,5 and 36 days after cessation of drilling in one of the bores NP-522, are also given. Although the temperature in the bore still differs considerably from equilibrium, it is possible to determine the temperature gradient with an accuracy better than 5% as soon as 5 days after drilling was finished.     

Heat flow and ground water flow in the Great Plains of the United States

Regional groundwater flow in deep aquifers adds advective components to the surface heat flow over extensive areas within the Great Plains province. The regional groundwater flow is driven by topographically controlled piezometric surfaces for confined aquifers that recharge either at high elevations on the western edge of the province or from subcrop contacts. The aquifers discharge at lower elevations to the east. The assymetrical geometry for the Denver and Kennedy Basins is such that the surface areas of aquifer recharge are small compared to the areas of discharge. Consequently, positive advective heat flow occurs over most of the province. The advective component of heat flow in the Denver Basin is on the order of 15 mW m⁻² along a zone about 50 km wide that parallels the structure contours of the Dakota aquifer on the eastern margin of the Basin. The advective component of heat flow in the Kennedy Basin is on the order of 20 mW m⁻² and occurs over an extensive area that coincides with the discharge areas of the Madison (Mississippian) and Dakota (Cretaceous) aquifers. Groundwater flow in Paleozoic and Mesozoic aquifers in the Williston Basin causes thermal anomalies that are seen in geothermal gradient data and in oil well temperature data. The pervasive nature of advective heat flow components in the Great Plains tends to mask the heat flow structure of the crust, and only heat flow data from holes drilled into the crystalline basement can be used for tectonic heat flow studies.     

Optimal design of supplemental viscous dampers for irregular shear‐frames in the presence of yielding

A methodology for the optimal design of supplemental viscous dampers for regular as well as irregular yielding shear‐frames is presented. It addresses the problem of minimizing the added damping subject to a constraint on an energy‐based global damage index (GDI) for an ensemble of realistic ground motion records. The applicability of the methodology for irregular structures is achieved by choosing an appropriate GDI. For a particular choice of the parameters comprising the GDI, a design for the elastic behavior of the frame or equal damage for all stories is achieved. The use of a gradient‐based optimization algorithm for the solution of the optimization problem is enabled by first deriving an expression for the gradient of the constraint. The optimization process is started for one ‘active’ ground motion record which is efficiently selected from the given ensemble. If the resulting optimal design fails to satisfy the constraints for other records from the original ensemble, additional ground motions (loading conditions) are added one by one to the ‘active’ set until the optimum is reached. Two examples for the optimal designs of supplemental dampers are given: a 2‐story shear frame with varying strength distribution and a 10‐story shear frame. The 2‐story shear frame is designed for one given ground motion whereas the 10‐story frame is designed for an ensemble of twenty ground motions. Copyright © 2005 John Wiley & Sons, Ltd.     

Heat flow and gravity in Czechoslovakia

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Damage evolution and fluid flow in poroelastic rock

We present a formulation for mechanical modeling of the interaction between fracture and fluid flow. Our model combines the classic Biot poroelastic theory and a damage rheology model. The model provides an internally consistent framework for simulating coupled evolution of fractures and fluid flow together with gradual transition from brittle fracture to cataclastic flow in high-porosity rocks. The theoretical analysis, based on thermodynamic principles, leads to a system of coupled kinetic equations for the evolution of damage and porosity. A significant advantage of the model is the ability to reproduce the entire yield curve, including positive and negative slopes, in high-porosity rocks by a unified formulation. A transition from positive to negative values in the yield curve, referred to as a yield cap, is determined by the competition between the two thermodynamic forces associated with damage and porosity evolution. Numerical simulations of triaxial compression tests reproduce the gradual transition from localized brittle failure to distributed cataclastic flow with increasing pressure in high-porosity rocks and fit well experimentally measured yield stress for Berea sandstone samples. We modified a widely used permeability porosity relation by accounting for the effect of damage intensity on the connectivity. The new damage-permeability relation, together with the coupled kinetics of damage and porosity evolution, reproduces a wide range of realistic features of rock behavior. We constrain the model variables by comparisons of the theoretical predictions with laboratory results reporting porosity and permeability variation in rock samples during isotropic and anisotropic loading. The new damage-porosity-permeability relation enables simulation of coupled evolution of fractures and fluid flow and provides a possible explanation for permeability measurements in high-porosity rocks, referred to as the “apparent permeability paradox.” The text was submitted by the authors in English.     

完整岩石在不同尺度上的屈服

对完整岩石力学机制的研究有助于更好地理解与屈服有关的应力-应变关系。屈服准则研究方法包括基于实验数据分析和基于微观力学的研究。屈服数学理论的研究目标是对应力和应变关系的理论描述和对弹塑性界限的识别。本文主要研究完整岩石在不同尺度上的屈服。从Weibull理论可知,岩石强度随尺度增大而减少,这已经通过单轴压缩强度（UCS）的Hoek-Brown方程得到证实。然而,围压能改变岩石强度及屈服。因此,本文利用直径为50mm和96mm的圆柱形砂岩样品在不同围压作用下的压缩实验来研究不同尺度下的岩石屈服,从实验中提取不同尺度下的屈服初始点并描述屈服面,最终给出简单数学形式的屈服准则。     

自适应横向变速参考速度选择方法

基于扰动理论的混合域波动方程波场外推算子,具有一定介质横向速度变化适应能力,是反射地震学中研究较多的成像方法。此类波场外推算子沿深度层进行波场外推,都存在参考速度选择问题。单参考速度波场外推算子,适应地下介质弱横向变速,而多参考速度波场外推算子可以提高横向变速的适应能力和成像精度,但要以大量计算为代价。本文提出的自适应多参考速度选择策略,根据外推层地质构造的复杂度和给定的速度门槛值自动选择参考速度个数,利用该策略构造混合域SSF、FFD、WXFD和GSP等多参考速度波场外推成像算法。盐丘模型理论数据测试结果表明,自适应多参考速度波场外推算法具有强横向变速适应能力和较高成像精度。     

A self-adaptive algorithm for choosing reference velocities in the presence of lateral velocity variations

Based on perturbation theory, the wave equation extrapolation operator with mixed domains has the ability to deal with lateral velocity variations. It is the image method that has undergone much research in seismology. All extrapolation operators face the problem of choosing the reference velocity due to continuation in depth. The wavefield extrapolation operator with a single reference velocity is suitable for media with weak lateral variation. The multi-reference velocity extrapolation operator can cope with severe lateral velocity variations and improve image accuracy. However, the calculation cost is large. We present a self-adaptive approach to automatically determine the number of selected reference velocities according to the complexity of structure and the given velocity threshold value. The approach can be used to construct the SSF, FFD, WXFD, and GSP multi-reference velocity wavefield extrapolation image algorithms. The result of a salt-dome model data test demonstrates that the self-adoptive multi-reference wavefield extrapolation algorithm has the ability to deal with severe lateral velocity variations and can also be used for structure edge detection. The method is flexible and computationally cost-effective.