Robert N. Harris Robert A. Sohn Shaul Hurwitz Karen Luttrell Julia E. Favorito 2021 <p><span>We report results from 149 heat flux measurements made over n ∼2-year interval at sites in and around a vapor-dominated geothermal field located at water depths of ∼100–120&nbsp;m in Yellowstone Lake, Wyoming. Measurements of both in situ temperature and thermal conductivity as a function of depth were made with a 1 m probe via a remotely operated vehicle, and are combined to compute the vertical conductive heat flux. Inside the ∼55.5&nbsp;×&nbsp;10</span>³<span>&nbsp;m</span>²<span>&nbsp;bathymetric depression demarcating the vapor-dominated field, the median conductive flux is 13&nbsp;W&nbsp;m</span>⁻²<span>, with a conductive output of 0.72&nbsp;MW. Outside the thermal field, the median conductive flux is 3.5&nbsp;W&nbsp;m</span>⁻²<span>. We observed 49 active vents inside the thermal field, with an estimated mass discharge rate of 56&nbsp;kg&nbsp;s</span>⁻¹<span>, a median exit-fluid temperature of 132°C, and a total heat output of 29&nbsp;MW. We find evidence for relatively weak secondary convection with a total output of 0.09&nbsp;MW in thermal area lake floor sediments. Our data indicate that vapor beneath the thermal field is trapped by a low-permeability cap at a temperature of ∼189°C and a depth of ∼15&nbsp;m below the lake floor. The thermal output of the Deep Hole is among the highest of any vapor-dominated field in Yellowstone, due in part to the high boiling temperatures associated with the elevated lake floor pressures.</span></p> application/pdf 10.1029/2020JB021098 en American Geophysical Union Heat flux from a vapor-dominated hydrothermal field beneath Yellowstone Lake article