New survey plumbs Mono Lake's depths for hydrothermal heat

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It is very hot below the cold waters of Mono Lake, which hosts one of the youngest volcano complexes in the United States.

Two researchers deploy a floating temperature instrument in a calm, smooth blue-green lake surrounded by mountains.

Deployment of a float that collects real-time lake and lakefloor temperature data.  Changes in subsurface temperature with time will be used to assess variations in heat flow, properties of lake sediment, and long term changes in lake temperature.

(Public domain.)

During the past 2,000 years, volcanism in the Mono Lake Volcanic Field has given rise to lava domes, flows, and uplifted lake sediments that protrude above the lake surface as islands. Volcanic eruptions in water-saturated environments like Mono Lake can sometimes result in explosive phreatomagmatic activity, making them especially hazardous. Despite evidence for recent eruptions in Mono Lake and along the Mono Craters to the south of the lake, relatively little is known about the geologic structure and possible position of magma underlying the lake, complicating hazard assessments.

To understand the source of heat and the potential for shallow magma below Mono Lake, in March of 2021, researchers from Southern Methodist University and the University of California at Berkeley collaborated with the California Volcano Observatory to a series of instruments that measure the real-time temperature of the lake’s water at multiple depths, and of the sediments underlying the lake floor. These measurements will help reveal subsurface geological structures, locate conduits through which fluids transport heat from underlying magma into the lake, and estimate the amount of heat that is transported from magma to the lake. Preliminary findings already suggest that a significant amount of heat is transported through the sediments into the lake, since some of the highest temperatures were measured in the sediments just to the east and to the south of Paoha Island.  To build on these results, the research team is planning additional instrument deployments in the Fall of 2021.