A steady flow of heat flow rises from the hot interior of the earth to the earth's surface. Measuring the heat flow density (unit: W/m²) at a location allows conclusions about the structural composition or dynamic processes in the subsurface. The heat flow density is calculated from the product of the vertical temperature gradient and the specific thermal conductivity of the subsurface.
The heat flow density in seafloor sediments is measured using a heat flow probe. The probe consists of a several meters long steel rod equipped with temperature sensors which gets pressed into the seafloor measuring the vertical temperature gradient. After the frictional heat from the penetration has subsided, a wire is used to heat up the rod. The thermal conductivity is then derived from the generated heat rate transferred to the surrounding sediments.
BGR has developed a unique so-called “hard ground” heat flow probe in order to carry out measurements even in solidified sediments with low sediment cover. The hard-ground probe is also equipped with a camera and light to transmit image data next to the temperature data via the ship's deep-sea cable. This ensures measurement in a controlled manner at suitable drop-off points.
