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The difference between Geothermal Temperature Gradient (GradT) and Unbiased Geothermal Temperature Gradient (GT) is that the former accounts for the effects of the seasonal/daily temperature variations ( , which are mostly noticeable only significant above Neutral Temperature Layer ).
The most common value of Geothermal Temperature Gradient away from tectonic plate boundaries is: GT = 0.025 ÷ 0.035 °C/m.
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