Heat flow measurements, continental

Abstract

Heat flowing from the surface of the continents cannot be measured directly. It is calculated as the product of the temperature gradient (most often measured in boreholes) and the thermal conductivity of the formation within which the temperature gradient was measured. Thermal conductivity can be measured in situ, but by far the majority of measurements are made on rock samples from the borehole, or from nearby outcrops of the relevant formations. Temperatures are usually measured by electronic transducers deployed on multi-conductor electrical cables or incorporated into “memory tools,” which are lowered into the borehole on steel or alloy wires. Fiber-optic cables can also be inserted into..