THE 

GEOTHERMAL RESEARCH PROGRAM 

OF THE U.S. GEOLOGICAL SURVEY 

GEOLOGICAL SURVEY CIRCULAR 862 
COVER 

These photographs ill ustrate the sequence of activi ties leading to the production of electricity 

from geothermal energy. In practice, the number and scope of studies undertaken during 

exploration differ from area to area. In general, knowledge gained from a combination of 

geologic. geochemicaL hydrologic, and geophysical studies leads to recommendations for drill 

sites: and if a productive reservoir of hot water or steam is found during drilling, the geothermal 

energy may be used to generate electricity. 

2 

1 

3 

5 4 

1. Geologist examining rock at outcrop during field mapping. 

2. Geochemist collecting sample of thermal water for subsequent laboratory analysis. 

3, Geophysicist reading gravimeter at outcrop during field survey. 

4, Drill rig in operation over target defined by results of foregoing field and laboratory studies. 

5, An electrical generating plant powered by geothermal steam. Condensate from cooling towers 

is visible. 
The Geothermal Research 

Program of the U.S. 

Geological Survey 

By Wendell A. Duffield and Marianne Guffanti 

GEOLOGICAL SURVEY CIRCULAR 862 

1982 
United States Department of the Interior 

JAMES G. WAIT, Secretory 

Geological Survey 

Dallas L. Peck, Director 

Library of Congress Cataloging in Publication Data 

Duffield, Wendell Arthur, 1941-

The Geothermal Research Program of the U.S. Geological Survey 

(Geological Survey Circular ; 862) 

Bibliography: p. 13-15 

Supt. of Docs. no.: 119.4/2:862 

1. Geothermal Research Program (U.S.). I. Guffanti, Marianne. II. Title. Ill. 

Series: United States. Geological Survey. Circular 862 

QE75.C5 no. 862 557.3s 82-600219 

[TJ280.7) [621.44) 

Free on application to Branch of Distribution, U.S. Geological Survey 

604 South Pickett Street, Alexandria, VA 22304 
CONTENTS 

Page 

Introduction --------------------------------------------------------------------------------------------------------------------------------------·----------------- 1 

Birth of the Geothermal Research Program---------------------------------------------------------------------------------------------- 1 

Organization ___________________________________________________________________________________________________________________________ ··---------------------------- 2 

Objectives ----------------------------------------------------------------------------------------------------------------------- ____________________________ 3 

Fiscal history --------·----------------------------------------------------------------------------------------------------------------------------------- 12 

Accomplishments ----------------------·----------------------------------------------------------------------------------·-------------------------- 14 

Present emphasis ---------------------------------------------------------------------------------··-------------------------------------------------- 23 

Geothermal development ------------------------------------------------------------------------------------------------------------------------------ 25 

References cited ----------·---------------------------------------------·------------------------------------------------------------------------------------- 28 

ILLUSTRATIONS 

Page 

FIGURE 1. Graph showing funding of Geothermal Research Program since 1972 ----------------------·----------------------------------------------- 3 

2. Circle diagrams showing allocation of 1980 budget of Geothermal Research Program___________________________ ____________ 5 

3. Photograph of geochemist sampling gas dissolved in thermal water from a research well in Yellowstone 

National Park-------------·-------------------------------------------------------------------------------------------------------------------------------------------··------------ 5 

4. Schematic diagrams illustrating generation of electricity from geothermal systems ------------------------------------------ 6 

5. Photograph of geologist mapping dike at Ship Rock, northwestern New Mexico--·----------------------------------------------- 7 

6. Photograph showing drilling of test well at Coso geothermal field, California___________________________________________ ____________ 7 

7. Photograph showing insertion of acoustic televiewer into geothermal well at Roosevelt, Utah_________________________ 7 

8. Plot of temperature against depth in research borehole, Newberry caldera, Oregon____________________________________________ 11 

9. Map of United States, showing locations of field-oriented research projects of Geothermal Research 

Program for 1980 ------------------------------------------------------------------------------------------------------------------------------------------------- ____________ 12 

10. Graph showing worldwide installed geothermal electrical capacity as a function of time_________________________________ 13 

11. Graph showing installed and expected electrical generating capacity at The Geysers, California, as a 

function of time --------------------·--------------------------------------------------------------------------------------------------------------------------------------------- 13 

TABLE 

Page 

TABLE 1. Summary of fund distribution of the Geothermal Research Program for 1980 --------------------------------------------------·- 4 

Length: 

Area: 

Temperature: 

Temperature gradient: 

Energy: 

Power: 

CONVERSION FACTORS 

1 kilometer (km) = 0.6214 mile (mi) 

1 km2 = 0.3861 mi 2 

Degrees Celsius (°C) = 5/9(degrees Fahrenheit-32) 

1 °C/km = 2.90°F /mi 

1 joule (J) = 0.239 calories (cal) 

= 9.480x10· 4 British thermal unit (Btu) 

10u; J = 1015 Btu= 1 quad= 6x109 barrels of oil 

1 megawatt (MW) = 106 J/s 

III 

The Geothermal Research Program of the 

U.S. Geological Survey 

By Wendell A. Duffield and Marianne Guffanti 

INTRODUCTION 

Geothermal energy is naturally occurring 

thermal energy (heat) within the Earth. Measurements in boreholes indicate that temperature 

increases downward within the Earth's crust at 

an average rate of about 30°C/km, and from this 

average geothermal gradient it has been calculated that about 4xl026 J of thermal energy, 

assuming a surface temperature of l5°C, is stored 

within the outer 10 km of the crust (White, 1965). 

However, only a very small fraction of this vast 

storehouse of energy can be extracted and used at 

the Earth's surface. Like other natural resources, 

such as ore minerals and solid or liquid fuels, 

geothermal energy is exploitable only where it 

occurs in accessible, anomalously high concentrations. The process of mining so intangible a 

commodity as thermal energy places another 

constraint on the exploitation of geothermal systems. Although most of the energy is stored in 

rocks, water and (or) steam that are contained in 

fractures and pore spaces of the rocks are the only 

naturally occurring media available for transferring this energy to the Earth's surface. Thus, 

both high temperature at relatively shallow 

(drillable) depth and sufficient water or steam to 

transfer thermal energy to the surface are needed 

to exploit geothermal systems. 

Naturally occurring systems of this sort, known 

as hydrothermal systems, are being increasingly 

developed and utilized as the cost of traditional 

forms of energy escalates. Moreover, considerable 

research within the geothermal community is 

presently aimed at forcing circulation of water 

through hot rocks that are dry and impermeable 

in their natural state in order to increase the 

amount of thermal energy that may be mined and 

used at the surface. Future technologic and economic developments will dictate what proportion 

of the overall content of thermal energy in the 

Earth's crust may actually be exploitable. 

Although prediction of such developments is difficult, it is noteworthy that the worldwide rate of 

1 

growth in electrical generating capacit~' from 

geothermal energy has been 7 percent per year 

since about 1945, whereas the projected rate of 

growth in the near future ranges as high as 19 

percent per year (Muffler and Guffanti, 1979). 

Geothermal energy is also being increasingly 

developed for nonelectrical applications. It seems 

likely that the economic climate responsible for 

such growth in the recent past will prevail for 

some time to come and that advances in technology will continue to accrue, thus promoting 

increased development of geothermal resources. 

BIRTH OF THE GEOTHERMAL 

RESEARCH PROGRAM 

Geothermal energy was first developed to generate electricity in 1904 at Larderello, Italy; yet as 

recently as 15 years ago such energy was considered little more than a curiosity in the United 

States. Such natural manifestations of g~othermal energy as geysers, boiling mudpots, and hot 

springs provided a basis for establishing national 

parks (for example, Yellowstone) and spas. and in 

a few places geothermal water was used for space 

heating (for example, Boise, Idaho, and Klamath 

Falls, Oregon); but no large-scale, systematic 

efforts were undertaken to assess and cevelop 

geothermal energy as a national resource. 

By the late 1960's, it was clear worldwide that a 

continuously growing demand for energ;r could 

not long be satisfied by available supplies of petroleum, the chief fuel being used to meet increased 

demand. This generally deteriorating relation 

between supply and demand was dramatized in 

1973, when an em bar go on petroleum export from 

the Middle East severly disrupted supplies of 

petroleum-derived fuel in the United States. 

Most U.S. citizens first became acutely aware of a 

growing energy problem while waiting in lines 

for hours to purchase gasoline for their automobiles. 

As part of a national effort to decrease dependence on petroleum through the developnent of 

alternative domestic energy resources, a Federal 
Geothermal Program was established in the early 

1970's. The U.S. Geological Survey played a major 

role in planning and implementing this program, 

and in 1971 the Survey's own Geothermal Research 

Program was formally established. 

The Geological Survey was well prepared to 

play a key role in the newly formed Federal 

Geothermal Program because years of ongoing 

field and laboratory research in several disciplines had accumulated a readily available base 

of know ledge and expertise with regard to geothermal fluids, volcanoes, and the thermal structure of the Earth's crust. For example, by 1970, 

studies of geothermal systems in Yellowstone 

National Park, probably the most abundantly 

endowed natural laboratory in the world for such 

research, had already yielded clues to the recognition of some fundamental differences between 

types of geothermal systems (White and others. 

1971) and to the determination of their temperatures at depth (Fournier and Rowe, 1966) from 

analysis of water collected at surface hot springs. 

Similarly, studies of the generation and flow of 

heat within the Earth provided a scientific framework critical to a regional resource assessment of 

geothermalenergy(Lachenbruch,1970;Sassand 

others, 1971), and studies of volcanoes (for example, Smith and Bailey, 1968) provided an understanding of the formation and accumulation of 

magma, the inferred source of thermal energy 

that underlies and drives high-temperature 

hydrothermal systems in the Earth's crust. 

Accordingly, by the early 1970's, when the 

Nation embarked on a major effort to develop 

domestic energy resources, the U.S. Geological 

Survey was well equipped with a team of talented 

researchers and an advanced understanding of 

geothermal energy, and thus assumed a key role 

in characterizing and assessing geothermal resources in support of the Federal Geothermal 

Program. 

ORGANIZATION 

The research of the Geothermal Research Program is carried out by the Water Resources and 

Geologic Divisions of the Survey, and is administered by the Geologic Division. The overall direction of the program is handled by a program 

coordinator (presently Wendell A. Duffield, Menlo 

Park, California), who operates under the authority of the chief of the Office of Geochemistry and 

2 

Geophysics (presently Benjamin A. Morgan, Reston, Virginia). Donald E. White (Menlo Park, 

California), in his capacity as senior scientist in 

geothermal research, serves as advisor to the 

program. Franklin H. Olmsted (Menlo Park, 

California) coordinates the part of the program 

carried out by the Water Resources Division, and 

Donald W. Klick (Reston, Virginia) manages a 

component of the program devote'i to research 

through grants and contracts to non-Survey 

organizations. 

The program's inhouse research consists of a 

host of geologic, geochemical, geonhysical, and 

hydrologic projects, nearly 90 of which have been 

active each year since 1975. The component of 

research supported by grants to and contracts 

with organizations outside the SurYey was established in 1975, and since then appr0ximately 15 

percent of the program's budget has been allocated each year to such outside investigations, 

which supplement and complemert the inhouse 

studies. 

The Geothermal Research Program is organized and administered separately from the classification, evaluation, and leasing of Federal lands 

for geothermal development, activities that are 

carried out by the Conservation Division of the 

Geological Survey. However, mucl' of the information generated by the program h~ars directly 

on the Conservation Division's geothermal projects, and timely exchange of this information is 

accomplished through regular contacts between 

the program coordinator, other scientists, and the 

Conservation Division's geothermal staff. which 

is headquartered in Menlo Park, California. 

The U.S. Department of Energy's Division of 

Geothermal Energy is the lead ager cy in the Federal Geothermal Program, a role that is reflected 

in a budget which has remained about 15 to 20 

times larger than that of the Geological Survey's 

Geothermal Research Program. The Department 

of Energy emphasizes site-specific studies of 

reservoir confirmation and evaluation, the development of advanced technology related to geothermal exploration and exploitation, and investigation of the institutional and legal barriers to 

geothermal development. This emphasis seeks to 

promote development of geothermal resources by 

private industry. The Geothermal Pesearch Program has a legislated mandate to assess the 

Nation's geothermal resources and thus concentrates its efforts on more generic and regional 
studies, aimed at the characterization and fundamental understanding of all types of geothermal systems and at an overall national 

assessment of the distribution and magnitude of 

geothermal resources. The programs of the two 

agencies are complementary and closely coordinated. The Survey maintains a scientist (presently Charles G. Bufe, Reston, Virginia) on 

assignment to the Department of Energy in 

Washington. D.C.; Morgan and Klick, the other 

key staff members headquartered in the Washington, D.C., area, supplement Bufe's day-to-day 

liaison activities and coordinate activiti~s of 

common interest with other Federal agencies. 

OBJECTIVES 

The principal objectives of the Geothermal 

Research Program are to characterize all types of 

geothermal systems, to map their distribution, 

and to assess their potential as sources of thermal 

energy. These objectives are designed to provide 

information on the geothermal component in 

planning national energy policy. Important 

derivative objectives are to develop and improve 

methods of exploration for geothermal resources 

and to examine environmental problems. such as 

grou d subsidence, seismicity, and hydrologic 

chan es, that may be induced by exploitation of 

geot ermal fields. 

FISCAL HISTORY 

ding for the Geothermal Research Progra since 1972 has varied considerably (fig. 1). 

Afte a 3-year period of initial growth, funding 

rem ined near the $9 million to $10 million level 

thro gh 1978. In 1979 the budget was supplemen ed by $2 million earmarked primarily for 

rese rch contracted outside the Geological Survey. his increase was for 1979 only and so was 

drop ed from the 1980 budget; during 1981, 

furt er reduction of the program's budget by 

abou $2.3 million reflects a relatively higher 

prio ity for studies of other kinds of energy 

reso rces. When this reduced budget is adjusted 

for i flation, buying power is seen to be considerably ess. The 1981 budget of about $7.7 million is 

equi alent to about $2.5 million (1972 dollars) 

whe adjusted for the Consumer Price Index 

(CPI inflation rates published annually by the 

U.S Department of Commerce. or to about $4.5 

3 

million (1972 dollars) when adjusted for ar annual 

inflation rate of 6 percent (fig. 1). The 8,1rvey's 

program has maintained a high level of productivity in spite of such great erosion of the real 

buying power of its research funds. However, the 

rate at which the Survey can accomplish its mandated mission necessarily diminishes in r~sponse 

to budget reductions. 

The allocation of funds in 1980 illustrates a 

typical year in the history of the program. The 

multidisciplinary character of the research is 

evident from the list of the Geological Survey's 

organizational units that have participated in the 

program (table 1); this broad character reflects 

the need to study both water and rocks and the 

host of complex interactions between the two. The 

$1,014,723 in support of research outside the 

Survey in 1980 was nearly 50 percent less than 

the average amount spent in each of the previous 

5 years. The $2.3 million budget reduction for 

1981 is partly accommodated by decreasing this 

level further as current contracts terminate, and 

the balance by a general reduction in inhouse 

projects. 

en 

a: 

s 

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8 

u... 

0 

en 

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YEAR 

FIGURE 1.- Funding of Geothermal Research Program 

since 1972. CPI, Consumer Price Index. 
The 1980 budget may also be viewed in terms of 

general topics of research or of the three principal categories of expenditure that constitute an 

individual project (fig. 2). The preponderance of 

funds spent on resource characterization and 

inventory reflects the primary mission of the 

Survey's Geothermal Research Program within 

the overall Federal Geothermal Program. 

ACCOMPLISHMENTS 

Major accomplishments of the Geological Survey's Geothermal Research Program are documented in the nearly 800 reports and maps published since its inception. A current listing of 

these publications is maintained in the program 

coordinator's office, Menlo Park, California, and 

in the Office of Geochemistry and Geophysics, 

Reston, Virginia, and is available on request (see 

addresses on inside back cover). Cor ies of reports 

and maps generally may be found at one or more 

of the Geological Survey libraries (Menlo Park, 

California; Denver, Colorado; Reston, Virginia), 

and some may be obtained directly from the 

authors. 

Space does not permit a summanr of the many 

scientific accomplishments of the program to 

date, but a few highlights are indicative of its 

overall productivity. Fundamental progress has 

resulted from studies of the chemical and physiTABLE 1.-Summary of fund distribution of the Geothermal Research Program for 1980. 

Geologic Division 

Office of Energy Resources 

Branch of Oil and Gas Resources······················------------------------·-----------------------·--------------------- $148,950 

Total --·------------------------------------------------------------------------------------------------------------------------------------------- 148,950 

Office of Mineral Resources 

Branch of Alaskan Geology---------------------------------------------------------------------------------------------------------- 47,510 

Branch of Western Mineral Resources ----------------·--------·------------------------------------------------------------ 19,428 Branch of Resource Analysis ______________________________________________________________________________________________________ 137,036 

Total ---------------------------------------------------------------------------------------------------------------------------------------------- 203,974 

Office of Regional Geology 

Branch of Engineering Geology-------------------------------------------------------------------------------------------------- 20,000 

Branch of Central Regional Geology----------------·---------------------------------------------------------------------·- 308,535 

Branch of Western Regional Geology --------------------------------------·----------·----------------------------------·--- 61,883 

Total ------------------------· ___________ -------------------------------------------------------------------------------------------------------- 390,418 

Office of Geochemistry and Geophysics 

Branch of Experimental Geochemistry and Mineralogy -------------------------------------------------- 546,024 

Branch of Field Geochemistry and Petrology ----------------------------------------------------------------------1.354,213 

Branch of Isotope Geology _ --------------------··---------------------------------------------------------------------------------- 351,409 Branch of Regional Geophysics __________________________________________________________________________________________________ 540,517 

Branch of Electromagnetism and Geomagnetism -------------------------------------------------------------- 528,813 

Branch of Petrophysics and Remote Sensing ------------------------------------------------------------------------ 263,959 

Total --------------------------------------------------------------------------------------------------------------------------------------------3,584,935 

Office of Earthquake Studies 

Branch of Seismology ________________________________________________________________________________________________________________ 1,123,4~2 

Branch of Ground Motion and Faulting---------------------------------------------------------------------------------- 127,3<18 

Branch of Tectonophysics------------------------------------------------------------------------------------------------------------ 723,054 

Total --·---------------------------------------------·---------------------·---------------------------------------------·-----------------------1,973,824 

Office of Geochemistry and Geophysics program functions 

Geothermal Research Program coordination and support------------------------------------------------ 160,8<11 

Extramural grants and contracts ---------·--------------------------------------------------------------------------------1.014,723 

Total -----------------------------------------------------------·--------------------------------------------------------------------------------1.175,564 

Geologic Division total ________________________________________________________________________________________________________ 7,4 77,665 

Water Resources Division total --------------------------------------------------------------------------------------------------------2,398,335 

Grand total ------------------------------------·-----------------------------------------------------------------------------------------$9,876,000 

4 
Resource 

characterization 

Rock porosity/permeability 

A 

B 

Resource 

inventory 

Exploration 

technology 

Other expenses 

FIGURE 2.- Allocation of 1980 budget of Geothermal Research 

Program by general research topics (A) and the three 

principal categories of a typical project (B). "Assessments" designates non salary, overhead costs of operating 

the U.S. Geological Survey; "Other Expenses" designates 

direct research costs, such as field and laboratory 

expenses. 

5 

cal properties of geothermal fluids (fig. 3). 

Research carried out before formal establishment of the Geological Survey's Geothermal 

Research Program led to a distinction between 

vapor-dominated (dry steam) and hot-water convective hydrothermal systems, on the basis of the 

chemistry of the fluids that leak to the surface 

from such systems (White and others, 1971). 

Vapor-dominated systems are developed to produce electricity at Larderello, Italy; Matsukawa, 

Japan; and The Geysers, California. Such systems are attractive for development because 

wells drilled into them produce superheated 

steam that can be routed directly through a turbine without the need to separate steam from 

water or to dispose of large volumes of waste 

water-relatively costly procedures that attend 

the exploitation of hot-water systems (figs. 4A, 

4B). Thus, recognition of vapor-dominated systems from the study of geothermal fluids collected at the surface is clearly of great economic 

value. 

Simultaneously with the recognition of these 

two types of convective hydrothermal systems 

and as a continuing research effort, several techniques have been developed to estimate the temperature in an underlying geothermal reservoir 

FIGURE 3.- Geochemist sampling gas dissolved in thermal 

water from a research well in Yellowstone National Park. 

Geochemical studies of fluids from such wells and from 

hot springs allow scientists to distinguish vapor-dominated from hot-water geothermal systems and to estimate 

subsurface temperatures. 
c. 

E 

0.. " 

f 

~ . tk 

?u~ 

EXPUNATION 

Dwater 

[ill] Steam 

A 

EXPUNATION 

Dwater 

~Steam 

B 

EXPUNATION 

Dwater 

~ Freon vapor 

~ FnK>n liquid 

c 

c: 

0 

·~ 

.!; 

6 

from the chemistry of the thermal water that 

leaks to the Earth's surface (for example, Fournier and Truesdell, 1973; Truesdell and Fournier, 

1976, 1977; Fournier, 1977, 1979, 1981; Fournier and 

Potter, 1979). The successful development and 

widespread use of these chemical geothermometers has resulted in economic benefits that already 

exceed the total cost of the Survey's Geothermal 

Research Program, by greatly increasing the 

chances of finding a high-temperature hydrothermal system during drilling. In broad recognition of their value, such geochemical studies, 

pioneered by the Survey, are now applied as 

standard exploration tools worldwide. 

Because most high-temperature geothermal 

systems are within or adjacent to volcanic fields 

that are less than 2 million years old, early program emphasis was on understanding the formation and evolution of crustal magmatic systems 

that constitute the roots of such fields. Building 

on the results of their earlier Survey research in 

volcanology, Smith and Shaw (1975, 1979) developed a method for calculating the thermal energy 

contained within a magmatic system on the basis 

of the age and volume of volcanic rocks erupted 

from that system. Other studies examined how 

the state of stress in the Earth determines the 

size, shape, orientation, and growth of magmatic 

conduits (Pollard and Muller, 1976), and how 

magma solidifies in such conduits during flow to 

the surface (fig. 5; Delaney and Pollard, 1982). In 

addition, several volcanic fields of the Western 

United States were targeted for intensive study 

to provide the information needed to evaluate the 

geothermal potential of each field. As a result, 

major progress has been made in understanding 

the histories of volcanism in the Geysers-Clear 

Lake area (Donnelly-Nolan and others, 1981; 

FIGURE 4 .- Schematic diagrams illustrating the generation of electricity from 

geothermal systems (from Muffler, 

1977). A , Vapor-dominated system; dry 

steam goes directly from wellhead to 

turbine. B. Hot-water system; waste 

water leaving separator and condenser 

is much more abundant than for a 

vapor-dominated system. C. Low-temperature hot-water system; geothermal 

fluids are used to heat a second fluid 

with a lower boiling temperature that 

is routed through a turbine. 
FIG URE 5.- Geologist mapping dike at Ship Rock, northwestern New Mexico. Such studies help explain how 

fractures form in the Earth's crust and how magma 

moves within the crust. 

FIGURE 6.- Drilling of a 1,477-m-deep test hole at Coso 

geothermal field, California. Study of rhyolite dome in 

background and other nearby rhyolite domes in the area 

suggests that partially molten rock may be present at 

several kilometers depth and may serve as a source of 

heat for hydrothermal system penetrated by this drill 

hole. 

7 

Hearn and others, 1981), Long Valley (Bailey and 

others, 1976) and Coso (fig. 6; Duffield and others, 

1980), California; at Newberry Volcano, Oregon 

(MacLeod, 1978); in the San Francisco Mountains, Arizona (Moore and Wolfe, 1976; Ulrich 

and others, 1979); at Ship Rock, New Mexico 

(Delaney and Pollard, 1981); and at Yellowstone 

National Park (Christiansen, 1982). Research 

continues on these and other volcanic regions, 

such as the Cascade Range of Washington, 

Oregon, and northern California, and the Snake 

River Plain of southern Idaho. In general, these 

studies of volcanic fields and magmatic systems 

have greatly increased our know ledge of the processes by and rates at which material and thermal energy move within magmatic and associated hydrothermal systems-knowledge that is 

critical to understanding the creation, functioning, and longevity of exploitable geothermal 

resources. 

To characterize the magmatic roots of volcanic 

systems further, a seismic technique has been 

developed to map zones of relatively low seismic 

velocity that may represent molten or partially 

molten rock within the Earth's crust and upper 

mantle. These seismic studies have demonstrated 

that such low-velocity material underlies volcanic fields at Long Valley, California (Steeples 

and Iyer, 1976); at Yellowstone National Park 

(lyer, 1979); in the Geysers-Clear Lake area, California (lyer and others, _1979); at Coso, California 

(Reasenberg and others, 1980); at Roosevelt Hot 

Springs, Utah (Robinson and Iyer, 1979); and in 

the San Francisco Mountains, Arizona (Stauber, 

1980). In each of these volcanic fields, the existence of magma at depth has been independently 

inferred from the history of volcanism reconstructed through geologic studies. Thus, the geologic and seismic data together provide important constraints on any understanding of magmarelated geothermal systems, and in specific areas 

they confirm that magma exists today as the 

source of heat for such systems. Geophysicists can 

also detect the flow of magma within the Earth's 

crust from precise measurements of ground deformation at the surface (Swanson and others, 

1976). Theoretical models (Pollard and Holzhausen, 1979) of the interaction between magmafilled fractures and the surface allow an estimate 

of fracture location, size, and heat content from 

such measurements. 
By mapping the paths of seismic waves gener~ 

ated by controlled explosions, the seismic structure of the Earth's crust beneath the Imperial 

Valley, California, one of the most richly endowed 

geothermal areas in the United States, has 

recently been delineated; geothermal systems 

were found to be associated with zones of relatively high seismic velocity in the sediment that 

fills the valley (Fuis and others, 1982). These 

velocity anomalies are inferred to arise from concentrations of minerals that were deposited in 

pore spaces of the valley-filling sediment by convective hydrothermal fluids. Thus, this seismic 

technique provides a tool for exploring sedimentfilled valleys and may be especially valuable in 

such geologic settings to help locate convective 

hydrothermal systems that have no such surface 

manifestations as hot springs and fumaroles. 

Geothermal systems with temperatures between about 90° and 150°C are dominated by hot 

water and commonly result from deep circulation 

of water of surface origin along faults and fractures in areas of relatively high geothermal 

gradient. Such a system exists at the Raft River, 

Idaho, where Geological Survey studies guided 

exploration for wells to support a recently completed experimental binary-cycle electric powerplant (fig. 4C; Williams and others, 1976; Mabey 

and others, 1978; Mabey, 1980). 

Measurements of the temperature gradient in 

the Earth's crust have led to the recognition of 

several large regions of differing heat flow and 

have defined local areas of higher than average 

heat flow that provide targets for further study. A 

recently updated map of heat flow for the conterminous United States (Sass and others, 1981a) 

is widely used by researchers interested in heat 

flow and the thermal regime of the Earth's crust. 

Considerable effort has been focused on the Western United States, especially the Basin and Range 

province in Nevada and Utah, where heat flow is 

generally high but varies. Theoretical analysis 

indicates that such elevated heat flow may result 

from the intrusion of mantle-derived magma into 

the crust in response to ongoing crustal extension 

(Lachenbruch and Sass, 1978), an interpretation 

consistent with the tectonic regime indicated by 

other geologic and seismic data. Additional measurements have enlarged the known area of high 

heat flow in the Basin and Range from an originally rather restricted part of Nevada (the socalled Battle Mountain high) to a broader region 

8 

that includes southern Idaho, southeastern 

Oregon, and possibly the Cascade Range in 

Oregon and northern California. 

To reduce the traditionally high costs incurred 

in measuring heat flow, the Geothermal Research 

Program's heat-flow project has successfully 

developed a probe that saves time and money in 

determining heat flow in unconsolidated sediment by eliminating the need to case the borehole 

and reenter it for temperature measurements 

after thermal equilibrium has been attained 

(Sass and others, 1979, 1981b). 

Because most geothermal systems are more 

electrically conductive than the surrounding 

cooler rocks, geoelectrical techniques can be used 

to map the lateral and vertical extent of a geothermal system during surface exploration. The 

Geothermal Research Program has contributed 

to development of the versatility and variety of 

such methods. The standard exploration technique of direct-current (d-e) soundings is now 

augmented by self-potential (SP), audiomagnetotelluric (AMT), and magnetotelluric (MT) techniques, each differing in terms of the source of 

energy for the survey and in the range of frequencies and, thus, the effective depths examined. 

Using a combination of these techniques, the electrical structure of the Earth's crust and upper 

mantle can now be examined to depths of several 

tens of kilometers. Such relatively shallow probing techniques as d-e soundings and SP and AMT 

have been used to locate drilling targets by outlining the apparent extent of geothermal reservoirs 

within the upper 2 to 3 km of the crust (Zohdy and 

others, 1973; Hoover and Long, 1976; Zohdy, 

1978). At Kilauea Volcano in Hawaii, a hightemperature (365°C) well, the first such well to 

confirm the existence of an exploitable convective 

hydrothermal system at Kilauea, was sited principally on the basis of SP mapping (Zablocki, 

1977). Deeper probing techniques, chiefly MT, 

can provide information on the positions of bodies 

of magma and other heat sources, and thus complement the geologic and seismic studies. 

Interpretation of the data gathered during 

geoelectrical and seismic surveys is limited by 

incomplete knowledge of the behavior of rocks at 

the temperatures and pressures characteristic of 

geothermal environments. To address this limitation, the Geothermal Research Program has 

helped establish a laboratory to determine various rock properties under simulated geothermal 
conditions. Research in this laboratory, one of the 

best equipped in the world, yields information 

that is invaluable in improving the interpretation 

of geophysical data collected during field surveys 

(Hunt and others, 1979). 

To obtain reliable geophysical data directly 

from high-temperature geothermal wells, a varietyofwell-loggingequipment has been developed 

within the Geothermal Research Program. One 

especially useful innovation is the acoustic televiewer (fig. 7), which provides information on the 

size, orientation, and position of fractures that 

provide permeable pathways and allow hot fluids 

to be extracted from many geothermal systems 

(Keys and Sullivan, 1979). 

The component of the Geothermal Research 

Program that supports non-Survey organizations 

has resulted in considerable progress in geothermal research. This component of the program both supplements and complements inhouse 

projects, and promotes contacts that further collaboration among university, industry, and 

Government scientists. 

Two key publications of the Geothermal 

Research Program have synthesized the results 

of a myriad of individual projects to address one 

of the principal objectives of the ·program: a 

quantitative assessment of the Nation's geothermal resources. Publication of Geological Survey 

Circular 726, "Assessment of Geothermal Resources of the United States- 1975" (White and 

Williams, 1975), represented the first such national assessment based on a consistent, welldocumented methodology and constrained by 

tabulated data on the physics and chemistry of 

known geothermal systems. Geothermal resources were calculated as that fraction of thermal energy stored in the crust that might be 

recoverable at the surface, with reasonable 

assumptions of future technology and economics. 

Three years later, after the Geothermal 

Research Program had existed long enough to 

have completed studies of several of theN ation's 

principal geothermal systems, an updated assessment was published as Geological Survey 

Circular 790, "Assessment of Geothermal 

Resources of the United States- 1978" (Muffler, 

1979). Though differing in some details because 

of the large body of new data amassed between 

1975 and 1978, both assessments estimate that 

theN ation's geothermal resources are many times 

greater than the amount that is being used today. 

9 

For example, identified geothermal resources in 

215 hydrothermal-convection systems with subsurface temperatures greater than 90°C to a depth 

of 3 km were estimated in Circular 790 to be 

400x1018 J, equivalent to 23,000 MW-electric 

annual yield for 30 years (assuming that only 

about 10 percent of the thermal energy extracted 

at the surface is convertible to electricity). Such 

information contained in these assessments is the 

principal basis for planning the geothermal component of national energy policy and provides 

guidelines for establishing goals of electrical 

production within the overall Federal Geothermal Program. 

The Geothermal Research Program maintains 

a computerized data file on geothermal resources 

(GEOTHERM), so that the large number of 

accumulated data is readily available to Geological Survey researchers, State and other GovernFIGURE 7.- Acoustic televiewer being inserted into a geothermal well at Roosevelt, Utah, to map fractures in walls 

of borehole. 
ment agencies, and the general public. GEOTHERM contains information on the physical 

characteristics, fluid geochemistry, geology, and 

hydrology of hydrothermal-convection systems 

and thermal springs and wells (Teshin and others, 1979). GEOTHERM was used extensively to 

support the 1978 assessment of geothermal 

resources and is currently being used in the 

assessment of geothermal resources with subsurface temperatures less than 90°C. The retrieval of 

data from the file may be requested in writing 

(see address on inside back cover). Data in the 

GEOTHERM file on thermal wells and springs 

are also available through the General Electric 

Information Services Network. 

PRESENT EMPHASIS 

At the present time, a considerable part of the 

Geological Survey's Geothermal Research Program is devoted to multidisciplinary study of the 

Cascade Range of Washington, Oregon, and northern California. Geologic, geophysical, geochemical, and hydrologic projects will contribute the 

information needed to assess the geothermal 

potential of this volcanic region. In February 

1980, the Geothermal Research Program sponsored a conference at which more than 150 participants, representing private enterprise, academia, and State and Federal agencies, reported 

progress of their studies in the Cascade Range 

(Bacon, 1980). 

The Cascade Range is somewhat enigmatic to 

geothermal researchers; in spite of abundant 

active volcanoes that suggest the presence of 

underlying magma bodies as heat sources for 

convective hydrothermal systems, there are only 

a few, widely scattered surface manifestations of 

such systems. Many researchers hypothesize that 

this absence reflects drowning of geothermal systems at shallow depths by percolating snowmelt 

and cool rainwater. Brook and others (1979) estimated that at least 1,140x1018 J (the U.S.A. presently consumes energy at the rate of about 

100x1018 J per year) of geothermal energy lie hidden beneath such a blanket of cold ground water 

in the Cascade Range. Recent results of research 

drilling by the Geological Survey at Newberry 

Volcano on the east side of the Cascade Range in 

Oregon indicate that considerable geothermal 

energy is, indeed, present beneath a cooler shal10 

low zone. Temperatures in the upper 631 m of this 

borehole never exceeded 99°C, and the temperature profile to this depth clearly was perturbed 

by shallow groundwater. However, temperatures 

in the bottom part of the hole increased at a rapid 

rate to a maximum of 265°C at 932 m (fig. 8), 

where geothermal fluids were encountered in 

permeable rock (Sammel, 1981). One important 

objective of the Geological Survey's studies of the 

Cascade Range is to identify parts of this 1,000-

km-long chain of volcanoes where similarly 

promising drilling results may be expected. 

Additional thrusts of the Geological Survey's 

present program include a continuing attempt to 

calculate the recoverable energy contained in 

geopressured geothermal systems of the Gulf 

Coast region and a thorough review of the state of 

knowledge of geothermal resources in the northern Great Basin. Geopressured systems are characterized by hot water and dissolved methane 

trapped in deeply buried porous sedimentary 

rocks, and assessment of their energy potential 

depends critically on data that can be obtained 

only during closely monitored long- and shortterm flow of wells. Accordingly, the Survey's 

research is coordinated with a program of well 

testing sponsored by the Division of Geothermal 

Energy of the U.S. Department of Energy. Review 

of the information available on the Great Basin 

will lead to recommendations of additional studies needed to upgrade existing assessment of 

resources within this region of anomalously high 

heat flow. 

As a followup to Circulars 726 and 790, the first 

quantitative assessment of geothermal resources 

with subsurface temperatures less than 90°C is 

underway. Low-temperature geothermal fluids 

are appropriate for such nonelectrical uses as 

space heating, industrial drying, and agricultural applications. Future assessment needs include 

consideration of the geothermal energy that may 

be recoverable through hot-dry-rock technology 

(that is, a manmade geothermal reservoir created 

by forced circulation of water through rocks that 

are hot but essentially dry and impermeable in 

their natural state). Initial experiments by researchers at Los Alamos National Laboratory in 

New Mexico have yielded results that hold promise for further evaluation of the technology and 

economics of such systems. A need for periodic 

updating of the assessments of all types of geothermal systems will persist as more of their 
physical and chemical characteristics are determined, as new techniques for exploiting them are 

developed, and as the demand for energy grows. 

Many other facets of the Geological Survey's 

Geothermal Research Program, too numerous to 

detail here, address the general goals of understanding the nature, distribution, and magnitude 

of theN ation's geothermal resources. A listing of 

current projects is available from the program 

coordinator (see address on inside back cover). 

Figure 9 shows the locations of field-oriented 

research projects for 1980. 

GEOTHERMAL DEVELOPMENT 

The impetus to develop alternative sources of 

energy is reflected in the recent trend of installed 

geothermal electrical capacity. Present installed 

capacity is about 2,500 MW worldwide, and 

announced development plans suggest that the 

rate of growth of this capacity may more than 

double during the 1980's from its previous rate of 

7 percent per year (fig. 10; DiPippo, 1980). In the 

United States, considerable growth in generating capacity is underway at The Geysers in California, the site of most of the geothermal electri-

(/) 

a: 

200 

~ 400 w 

~ 

~ 

0... 

~ 

~ 600 

800 

• • 

50 

EXPLANATION 

• Measurements on June 11, 1981, 

before 1981 drilling 

• MeasurementsonJuly11, 1981, 

two hours after drill-rod pull 

• Bottom-hole temperatures before 

• daily drilling 

• • • • • • • • • • • • • • • • • 

• l. ... • 

100 150 200 250 

TEMPERATURE, IN DEGREE CELSIUS 

FIGURE 8.- Temperature against depth in research borehole, 

Newberry caldera, Oregon (after Sammel, 1981). 

11 

cal power production in the United Stat€s at this 

time (fig. 11). The present 908-MW capacity at 

The Geysers is roughly equivalent to that of a 

modern nuclear-powered generating plant and is 

sufficient for a city of about 1 million people; 

about 500 MW of additional capacity is expected 

to be installed in the next few years (Reed, 1981). 

Recently, 20 MW of geothermal electricf.l power 

from a high-temperature hot-water system (fig. 

4B) and a low-temperature, hot-water system 

(fig. 4C) came on line at Brawley and East Mesa, 

respectively, in the Imperial Valley of California. 

These developments represent the first production of electricity from hot-water geothermal systems in the United States. Additional electrical 

generation is anticipated from other hot-water 

fields in the Imperial Valley and in the Valles 

caldera, New Mexico; and at Roosevelt Hot 

Springs, Utah; Raft River, Idaho; and Puna, 

Hawaii, within the next few years. 

Worldwide installed capacity for nonelectrical 

uses of geothermal energy is about 8,010 MW 

(Gudmundsson and Palmason, 1981), and about 

115 MW of this capacity is in the United States. 

Japan, Hungary, and Iceland together account 

for 85 percent of the worldwide capacity. Iceland, 

where nearly 80 percent of all buildings are 

heated with geothermal water, is the world leader 

in this particular nonelectrical application of 

geothermal energy. Data generally are not available to chart the rate of growth of nonelectrical 

installed capacity, buf active development programs in several countries suggest considerable 

growth, similar to installed geothermal electrical 

capacity. 

Geothermal electrical power is included among 

the so-called alternative sources of enerTI' and 

thus commonly appears in lists with solar, wind, 

biomass, tidal, and ocean thermal-energy conversion, among others. Such grouping, however, is 

misleading, because within this group, geothermal is the only source of energy that is producing 

considerable electricity now and developing 

rapidly. Similarly, the technology for non~lectrical uses of geothermal fluids is well established, 

and exploitation has already resulted in a growing contribution to national and world energy 

needs. In a world troubled by foreseeable limitations on conventional sources of energy, an aggressive program of research supporting the exploration and exploitation of geothermal systems is 

highly desirable. 
"" 

)> 

() 

4Q_ - ) 8 

~~-~ ( 0 77 () 

~r 

'? 0 \ 

() I 

G 

100 

or 

u '-- r 

100 200 300 400MILES 

200 400 600 KILOMETERS 

I 

90' 

FIGURE 9.- Locations of field-oriented projects of the Geological Survey's Geothermal Research Program for 1980. 1, Cascade 

Range-hydrothermal alteration, hydrology, geology, fluid geochemistry, paleomagnetism, heat flow, aeromagnetic 

survey, geoelectric studies, seismicity, resource assessment, gravity; 2, Mount St. Helens-seismic studies; 3, Mount 

Hood-gravity, magnetics, geology, hydrology, fluid geochemistry, hydrothermal alteration, seismicity, thermal infrared 

sensing; 4, Newberry /Three Sisters Volcanoes-geology, hydrology, geoelectric studies; 5, Mount Mazama (Crater Lake)-

geology, petrology, geochronology, geophysics; 6, Klamath Falls-hydrology, hydrologic modeling; 7, Medicine Lake 

Volcano-geology, petrology, geochronology, geochemistry; 8, Mount Shasta-geology, petrology, geochronology; 9, Lassen 

Peak-geology, hydrothermal alteration, fluid geochemistry, geochronology, geoelectric studies. 10, Northeastern 

California Cascades-geology; 11, Geysers-Clear Lake area-geology, geochronology, seismicity, subsidence, fluid 

geochemistry, precision gravimetry; 12, Black Rock Desert-hydrology, geophysics, geochemistry, hydrologic modeling; 

13, Leach Hot Springs-heat flow, hydrologic modeling; 14. Dixie Valley-subsidence; 15, 16, Mono basin-Long Valleygeology, petrology, fluid geochemistry, geochronology, temperature logging, heat flow, seismicity, hydrology; 17, Coso 

area-geology, geochronology, geoelectric studies, seismicity, fluid geochemistry, gravity, aeromagnetics; 18, Imperial 

Valley-subsidence, seismicity, fluid geochemistry; 19, East Mesa-hydrologic modeling, temperature log?:ing, seismicity, 

self-potential; 20, San Francisco Mountains-geology, geoelectric studies, seismicity, geochronology, gravity, paleomagnetism; 21, Springerville volcanic field-geology; 22, Rio Grande rift and southwestern New Mexico-geoelectric 

studies, geology; 23, Ship Rock-geology; 24, Valles caldera-isotopic studies. hydrology; 25. Cuesta-geology, petrology, 

geochronology; 26, Creede-geology, geochronology, fluid-inclusion studies; 27, Utah-heat flow, fluid geochemistry, 

geology; 28, Roosevelt Hot Springs-seismicity, subsidence, borehole logging, fluid geochemistry; 29, Northern Nevadahydrology of hydrothermal systems, heat flow, regional geophysics, fluid geochemistry, geoelectric E'tudies: 30, Raft 

River-geology, borehole logging, subsidence, hydrologic modeling, heat flow, seismic reflection, geoelectrical studies. 

fluid geochemistry; 31, Snake River Plain-geology, heat flow. seismicity, geoelectric studies, gravity, raleomagnetism, 

geochronology, hydrology, fluid geochemistry; 32, Idaho batholith-fluid geochemistry; 33, Yellowstone National Parkhydrothermal mineralogy and geology, fluid geochemistry, isotope studies, heat flow, seismicity, seismic refraction, 

hydrology, geoelectric studies, volcanic geology and petrology, ground deformation; 34, Southwestern Mo"tana-regional 

hydrology; 35, Gulf Coast geopressured zone-hydrology, fluid geochemistry, stratigraphy and sedimentation; 36, Atlantic 

Coastal Plain-heat flow, subsurface geology; 37, Wrangell Mountains-geology, geochronology; r8. Aleutian-arc 

volcanoes-geology, eochronology, fluid geochemistry; 39, Hawaiian volcanoes-seismicity, ground deformation, fluid 

geochemistry, paleomagnetism, magma reservoirs, geophysics, geology. 

12 
en 

I= 100,000 <( 

3: 

<( 

(!) 

w 

~ 

~ 10,000 19 percent per year : .. ~ u 

<( 

a. 7 percent per year <( 

u 

...J 1000 <( 

u 

a: 

fu 

w 

...J 

w 100 ...J 

<( 

~ 

a: 

w 

:I: 

f0 

w 10 (!) 1920 1940 1960 1980 2000 2020 

YEAR 

FIGURE 10.- Worldwide installed geothermal electrical 

capacity as a function of time (from Muffler and Guffanti, 

1979). Dashed line indicates plants under construction or 

committed up to 1983. Dotted extrapolations can be 

interpreted as upper and lower limits of expected growth. 

1500 

en 

I= 

<( 

3: 

<( 

(!) 

w 

~ 

~ 

~ u 

<( 1000 a. 

<( 

u 

...J 

<( 

u 

a: 

fu 

w 

...J 

w 

;t 

~ 

a: 

w 

:I: 

f0 500 w 

(!) 

REFERENCES CITED 

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____ 1982, Solidification ofmagmaduringflow in a dike: 

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o~~~~=c~~~~~~~~~SL~~~~~~~~ 

1960 1965 1970 1975 1980 1985 

FIGURE 11.-Installed and expected generating capacity at The Geysers, California, as a function of time. Data collate -:I by L. J. 

P. Muffler (written commun., 1980). 

13 
DiPippo, Ronald, 1980, Geothermal energy as a source of 

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14 

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15 
GPO 587-041/54 
U.S. GEOLOGICAL SURVEY ORGANIZATIONAL PERSONNEL 

IN CHARGE OF THE GEOTHERMAL RESEARCH PROGRAM 

Wendell A. Duffield, Geothermal Program Coordinator 

U.S. Geological Survey 

345 Middlefield Road. MS 90-C 

Menlo Park, CA 94025 

Benjamin A. Morgan, Chief 

Office of Geochemistry and Geophysics 

U.S. Geological Survey 

National Center. MS 906 

Reston, VA 22092 

Donald W. Klick 

U.S. Geological Survey 

National Center, MS 906 

Reston, VA 22092 

Franklin H. Olmsted 

U.S. Geological Survey 

345 Middlefield Road, MS 67 

Menlo Park, CA 94025 

Charles G. Bufe 

DOE, Division of Geothermal Energy, RA-233 

Federal Bldg., MS 3344 

12th & Pennsylvania Avenue NW. 

Washington, DC 20461 

Project GEOTHERM 

U.S. Geological Survey 

345 Middlefield Road, MS 84 

Menlo Park, CA 94025