geothermal gradient

geology

Also known as: thermal gradient

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June 29, 2026

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The geothermal gradient refers to the rate at which Earth's temperature increases with depth. On average, this is about a 1°F rise for every 70 feet downward from the surface. This temperature increase is influenced by heat flow from the Earth's mantle, radioactive decay within the crust, and heat transported by molten rock.12

The geothermal gradient varies significantly across different regions. Areas with active volcanism or upwelling mantle may experience gradients of 40 to 100 °C per kilometer, while stable continental interiors typically have gradients of 25 to 35 °C per kilometer. These variations create different temperature conditions within the Earth's crust, impacting geological processes like metamorphism. Geothermal methods in exploration often involve measuring temperature gradients to identify heat flow anomalies and locate geothermal resources.23

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metamorphic rock
Temperature
…in Earth, known as the geothermal gradient, is the increase in temperature per unit distance of depth; it is given by the tangent to the local geotherm. The magnitude of the geothermal gradient thus varies with the shape of the geotherm. In regions with high surface heat flow, such as…
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…in Earth, known as the geothermal gradient, is the increase in temperature per unit distance of depth; it is given by the tangent to the local geotherm. The magnitude of the geothermal gradient thus varies with the shape of the geotherm. In regions with high surface heat flow, such as…
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igneous rock
Origin of magmas
…depth, given by the estimated geothermal gradient, and the experimentally based melting curve (solidus) of the peridotite are illustrated in Figure 2. At depth D, the geothermal gradient curve and the solidus of the peridotite have their closest approach, but the peridotite is still solid. Diverse mechanisms have been proposed…
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…depth, given by the estimated geothermal gradient, and the experimentally based melting curve (solidus) of the peridotite are illustrated in Figure 2. At depth D, the geothermal gradient curve and the solidus of the peridotite have their closest approach, but the peridotite is still solid. Diverse mechanisms have been proposed…
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permafrost
Air temperature and ground temperature
…annual air temperature and the geothermal gradient. The average geothermal gradient is an increase of 1 °C (1.8 °F) for every 30 to 60 metres (roughly 100 to 200 feet) of depth. Eventually the thickening permafrost layer reaches an equilibrium depth at which the amount of geothermal heat reaching the…
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…annual air temperature and the geothermal gradient. The average geothermal gradient is an increase of 1 °C (1.8 °F) for every 30 to 60 metres (roughly 100 to 200 feet) of depth. Eventually the thickening permafrost layer reaches an equilibrium depth at which the amount of geothermal heat reaching the…
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