Geothermal Gradient


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geothermal gradient

[¦jē·ō¦thər·məl ′grād·ē·ənt]
(geophysics)
The change in temperature with depth of the earth.

Geothermal Gradient

 

the amount by which the temperature of rock rises per 100 meters’ increase in the depth of the deposits. The average gradient for crust depths that are accessible to direct temperature measurement is taken to be approximately 3° C. It varies from place to place as a function of the shape of the earth’s surface, thermal conductivity of the rock, subterranean water circulation, the proximity of volcanic foci, and the various chemical reactions taking place in the earth’s crust. The regular rise in temperature with increasing depth shows the existence of heat flow from the interior of the earth to its surface. The amount of this flow is equal to the product of the geothermal gradient and coefficient of thermal conductivity.

References in periodicals archive ?
The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface.
The major energy source for planetary decompression and for heat emplacement at the base of the crust, source of the geothermal gradient, is the stored energy of protoplanetary compression.
Fletcher said : 'Available information suggests that the geothermal gradient beneath Saipan may be sufficiently steep to provide geothermal energy to generate electricity.
Further analysis was conducted with a numerical model to ac count for subsurface heterogeneity, the site geothermal gradient and the varying surface temperature.
Specific topics include the mechanics of fault distribution and localization in high-porosity sands of Provence, France; strain localization in geomaterials; the progression from damage to localization of displacement observed in laboratory testing of porous rocks; microscale damage evolution in compacting sandstone; influence of grain size and geothermal gradient on the ductile-to-brittle transition in arenaceous sedimentary rocks; fracture aperture, length, and pattern geometry development under biaxial loading; and improved seismic identification of inter-fault damage via a linked geomechanics-seismic approach.
The borehole is sufficiently deep that the lower section of the temperature-depth profile allows a reliable determination of the geothermal gradient, presumably free of the effects of recent climate changes.
Arcs under extension have a steep geothermal gradient and underplating of the crust by mafic magma may transfer sufficient heat to induce anatexis.
Several parts of the Indonesian archipelago, especially in Central Sumatra, are areas of high geothermal gradient.
A 2005 work program costing in excess of US$800,000 was carried out and included a detailed E-Scan Survey, a gravity survey, and the drilling of four geothermal gradient wells.
Through the combination of the DTS data and geothermal gradient, a deep insight into the well behavior is generated, which allows operators to analyze the flow volume and changes per section.

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