Geothermal Gradient

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geothermal gradient

[¦jē·ō¦thər·məl ′grād·ē·ənt]
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 geothermal gradient of indicated prospective regions is above 58[degrees]C/km and the average in Slovakia is about 38[degrees]C/km.
With so much magma lying close to the surface, Iceland's geothermal gradient is unusually high.
The one big question in Kettler's mind is whether a high enough geothermal gradient exists underground to power massive electric generators.
Fletcher said : 'Available information suggests that the geothermal gradient beneath Saipan may be sufficiently steep to provide geothermal energy to generate electricity.
It was contributed by the thinned out Earth crust (33 km in average), the geothermal heat flow density (83-111 mW/m2), and the high geothermal gradient (which is the highest in Vojvodina, 5.
A calculated P-T path for this kyanite-grade event in the Baltoro indicates that primitive garnet growth occurred on an initially high geothermal gradient (~30degC) followed by a near-isothermal rapid increase in pressure.
Further analysis was conducted with a numerical model to ac count for subsurface heterogeneity, the site geothermal gradient and the varying surface temperature.
It is interesting to note that the geothermal gradient found in areas being drilled for oil wells in Pakistan in the south reveals higher than normal thermal gradient of 40'C for every kilometer.
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.
g] geothermal gradient of the rock mass (m/[degrees]C)

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