THE USGS GEOTHERMAL PROGRAM

Patrick Muffler

Photo of USGS Menlo Park Geothermal Team.

USGS Geothermal project, 1994. (left photo l-r: Patrick Muffler, John Sass, Bob Tilling, Sara Boore, Susan Mayfield, Carolyn Donlin, and Mike Sorey).

The roots of the USGS Geothermal Research Program go back to 1945, when Don White began his career-long study of hot springs, initially focusing on a comprehensive three-dimensional study at Steamboat Springs, Nevada, and on the nature of geyser mechanisms at Steamboat Springs and Yellowstone. In 1963, White was joined by Patrick Muffler for investigations of the Salton Sea geothermal system (at a time when the temperatures, salinities, and rock-water interactions in that hydrothermal system were considered as almost fantasy). In 1965, White and Muffler joined forces with geochemists Bob Fournier (who had carried out experimental work on silica solubility with George Morey) and Al Truesdell for a comprehensive study of Yellowstone hydrothermal systems (partly funded by NASA), producing a unique three-dimensional data set documenting the temperature, pressure, fluid geochemistry, and hydrothermal minerals in the upper few hundred meters of these hydrothermal systems that are nearly everywhere at the boiling point. In 1970, White, Muffler, and Truesdell also elucidated the fundamental distinction between hot-water and dry-steam geothermal systems.

Other USGS research activities in the 1950’s and 1960’s also laid a foundation for the Geothermal Research Program. Notable were the investigations of conductive heat flow led by Art Lachenbruch, the recognition by Robert L. Smith of ash-flow tuffs and associated calderas, and the development of potential-field geophysics.

In the late 1960’s, Geologic Division under the guidance of Dallas Peck, recognized the opportunity for a research program aimed at the understanding and quantification of geothermal resources. Muffler led the production of several generations of Bureau and Department Issue Papers, which resulted in August 1971 in the formal inception of the USGS Geothermal Research Program. From a beginning of about $500,000 per year, the program quickly grew to a level of about $12,000,000 per year in the late 1970’s. 1975 was a banner year, with the hosting (under Bob Fournier’s leadership) of a two-week-long United Nations Geothermal Symposium in San Francisco and the publication of the first USGS assessment of geothermal resources of the United States. This assessment was updated and expanded in 1978, and still serves as the definitive geothermal resource assessment of the United States.

Most geothermal resources of the United States occur in the western states, and consequently activities of the Geothermal Research Program were carried out primarily from Menlo Park, but with important potential-field geophysics from Denver (under the leadership of Don Mabey) and Reston (experimental geochemistry and volcanic geology). The Program quickly expanded into Water Resources Division, with a focus on water geochemistry (led by Ivan Barnes), hydrologic modeling (led by Mike Sorey), and ground subsidence (Bern Lofgren).

Leadership of the Geothermal Research Program was vested in a Program Coordinator (in 1974, a position new to the USGS). Throughout the 22-year life of the Program, the Program Coordinator was located in Menlo Park, providing close communication and understanding of the scientific activities. Program Coordinators were Patrick Muffler (twice), Bob Christiansen (twice), Wendell Duffield, Peter Lipman, and Manny Nathenson. The Program received strong support from Washington and Reston managers, in particular Dick Fiske, Dallas Peck, Vince McKelvey, Bob Tilling, and John Filson. Leaders from Water Resources Division included Al Clebsch, John Bredehoeft, Frank Olmsted, Frank Trainer, and Mike Sorey.

Since inception, the Geothermal Research Progam emphasized the understanding of not only the hydrothermal systems, but also the underlying igneous activity that drives most of them. To this end, the Progam supported extensive studies of young volcanic systems, beginning initially with The Geysers/Clear Lake (Carter Hearn, Julie Donnelly-Nolan, and Bob McLaughlin) and Long Valley (Roy Bailey). Subsequent volcanic efforts included the Aleutians (led by Tom Miller), Coso (Wendell Duffield and Charlie Bacon), Lassen Peak (Mike Clynne and Patrick Muffler), Newberry (Norm McCloud), Medicine Lake (Julie Donnelly-Nolan), Crater Lake (Charlie Bacon), Mt. Shasta (Bob Christiansen), Yellowstone (Bob Christiansen and Wes Hildreth), Questa (Peter Lipman), and Kilauea Volcano. These studies provided a firm foundation for the Volcano Hazards Program, which began formally in 1981 after the eruption of Mount St. Helens.

The Geothermal Research Program also carried out extensive geophysical studies of magmatic-geothermal systems. Studies under the leadership of John Sass, Art Lachenbruch, Mike Sorey, Steve Ingebritsen, and Manny Nathenson contributed extensively to the understanding of both conductive and convective heat transfer in the Earth’s crust. Extensive seismic studies were carried out, led primarily by H. M. Iyer and Dave Hill. Electrical studies were led by Adel Zohdy, magnetotelluric studies by Dal Stanley and Don Hoover, and gravity and magnetic studies by Don Mabey, Rick Blakely, and Bob Jachens. The Geothermal Research Program provided extensive support to Conservation Division and its geothermal leasing program, primarily through gravity studies (led by Don Mabey) and geochemical sampling (led by Bob Mariner).

Under the leadership of Bob Fournier and Al Truesdell, the Geothermal Research Program was the leader worldwide in the development of chemical geothermometers that used chemical and isotopic analyses of hot springs to deduce the temperatures of underlying geothermal reservoirs. The techniques developed by the USGS are universally recognized as essential components of any geothermal-exploration program. Hydrothermal alteration studies (Terry Keith and Keith Bargar) were also carried out on core and cuttings from Yellowstone and Mt. Hood, as well as fumarole samples from Katmai.

Beginning with the Salton Sea work in the early 1960’s, the geothermal activities of the USGS have provided much of the scientific underpinning to commercial geothermal development, both in the United States and internationally. USGS personnel have been active as directors of the Geothermal Resources Council and the International Geothermal Association since their inceptions, have served as Associate Editor of Geothermics, and have contributed (primarily through USAID and the United Nations) to geothermal investigations in countries including Mexico, Indonesia, Eritria, New Zealand, Italy, the Philippines, Iceland, Japan, South Korea, Israel, Jordan, Guatemala, Costa Rica, Panama, and El Salvador.

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