I am a volunteer Scientist Emeritus with the California Volcano Observatory, a unit of the USGS Volcano Science Center. My two decades of emeritus research has focused on the volcanic geology of northeastern California, in particular Lassen Volcanic National Park and the Cascades Volcanic Arc extending north towards Mount Shasta and Medicine Lake volcano.
Prior to formal retirement from the USGS in 2001, most of my scientific research was on hot springs and geothermal energy, including studies of volcanic geology and geothermal phenomena in the Lassen region of northeastern California, the geologic mapping of the southernmost Cascade Range of the western United States, studies of active hydrothermal metamorphism in the Salton Sea geothermal system in southern California, research drilling and mapping of geyser basins in Yellowstone National Park, investigation of the Larderello geothermal region of Italy, and studies of geothermal areas in the Taupo volcanic belt of New Zealand. Much of my scientific contribution involved estimation of geothermal resources, including developing a uniform methodology subsequently applied world-wide. I participated in the 1976 geothermal resource assessment of central and southern Tuscany in Italy, and I led the 1968 geothermal resource assessment of the United States.
I also served in various USGS managerial roles, including Coordinator of the USGS Geothermal Research Program (1971–1976 and 1983–1987), Coordinator of the USGS Volcano Hazards Program (1983–1987), Chief, Branch of Igneous and Geothermal Processes, 1982–1987 and Western Regional Geologist (1997–2000; a position in the Senior Executive Service responsible for all Geologic Division activities west of the Rocky Mountains).
1954–1956: Employed by USGS on Purchase Order (Form 44) and then as GS-1 to collect vertebrate fossils in Mojave Desert on weekends from college.
1956–1958: Summer field assistant for USGS in Montana., Idaho and Nevada.
1959–1961: Summer employment as USGS geologist, mapping Frenchie Creek quadrangle, Nevada.
1962–1963: Full-time USGS employment as geologist mapping on Baranof Island and Keku Straits in SE Alaska.
1964–1969: Studies of active hydrothermal metamorphism in the Salton Sea geothermal field of Southern California; geologic mapping and research drilling in geyser basins of Yellowstone National Park.
1970: Detail to Geophysics Division, New Zealand Department of Scientific and Industrial Research to study geophysical techniques for geothermal exploration
1971–1976: Coordinator, USGS Geothermal Research Program.
1976–2022: Geothermal and volcanic studies in Lassen segment of the Cascades Volcanic Arc.
1976–1977: Developed techniques of geothermal resource assessment at the National Electrical Agency of Italy (ENEL), under a cooperative agreement between the USGS Energy Research and Development Administration (ERDA) and ENEL.
1977–1978: Leadership of revised geothermal resource assessment of the United States.
1983–1987: Chief, Branch of Igneous and Geothermal Processes and Coordinator of USGS Geothermal Research and Volcano Hazards Programs.
1997–2000: Western Regional Geologist, responsible for Geologic Division activities west of the Rocky Mountains.
2001–2022: Volunteer Scientist Emeritus, Volcano Science Center, focusing on studies in the Lassen segment of the Cascades Volcanic Arc
Education and Certifications
1954: Graduate, Webb School of California (valedictorian)
1958: B.A. in geology, Pomona College (Magna Cum Laude)
1962: Ph.D. in geology, Princeton University
1997: Federal Executive Institute, Charlottesville VA
Affiliations and Memberships*
Geothermal Resources Council
Board of Directors, 1978–1983, 1992–1997
Second Vice-President, 1982
Education Committee Chair, 1980–1981
Publications Committee, 1992–present; responsible for GRC on-line library
Honors and Awards Committee, 1992–1995; Chair 1994–1995
Annual Meeting Advisory Committee, 1992–1993
Inspectors Committee, 1994
Technical Standards Committee, 1997
International Geothermal Association
Organizational Working Group, 1987–1989
Board of Directors, 1989–1995
Audit Committee Chair, 1989–1990
Information Committee, 1990–1997; Chair 1990–1992
Bylaws Committee, 1990
Program Committee, 1989–1994
Editor, IGA News, 1992–1993
American Geophysical Union
Chair of the Board of Associate Editors of the Geophysical Monograph Series, 1985–1986
Macelwane Medal Subcommittee 1989–1992; Chair 1990–1992
Meetings Committee, 1992–1996; Acting Chair 1993; Chair 1994–1996
Planning Committee, 1994–1996
Information Technology Committee, 1996-present
Geological Society of America, Fellow
Committee on Promotion of the Science of Geology, 1968
Society of Economic Geologists
Committee on Committees, 1983
Admissions Committee, 1984–1986
Phi Beta Kappa
Honors and Awards
Phi Beta Kappa scholar, Pomona College, 1958
Woodrow Wilson Fellowship for study at Princeton University 1958–1959
National Science Foundation Fellowships for study at Princeton University, 1959–1961
Meritorious Service Award, Department of the Interior
Distinguished Service Award, Department of the Interior, 1990
Joseph Aidlin Award, Geothermal Resources Council, 1988
Best Guidebook Award for Lassen guidebook, Geoscience Information Society, 2016
Dallas Peck award for Emeritus service, 2021
Abstracts and Presentations
Muffler, L.J.P., 1963, Forcible emplacement of epizonal plutons in the Cortez Mountains, north-central Nevada (abs.): Geological Society of America, Special Paper 73, p. 208.
Muffler, L.J.P., and White, D.E., 1965, Recent metamorphism of Pliocene and Quaternary sediments of the Salton Sea geothermal field, California, USA (abs.): Abstracts of the International Symposium on Volcanology, New Zealand, p. 119–120.
Muffler, L.J.P., White, D.E., Truesdell, A.H., and Fournier, R.O., 1967, Violent late Pleistocene hydrothermal explosions in Yellowstone National Park (abs.): Geological Society of America Annual Meeting, New Orleans, p. 158.
Muffler, L.J.P., and White, D.E., 1968, Origin of CO2 in the Salton Sea geothermal system, southeastern California, U.S.A. (abs.): International Geological Congress, 23d Session, Prague, Czechoslovakia, p. 385.
White, D.E., Muffler, L.J.P., Truesdell, A.H., and Fournier, R.O., 1968, Preliminary results of research drilling in Yellowstone thermal areas (abs.): American Geophysical Union Transactions, v. 49, no. 1, p. 358.
Honda, Sakuro, and Muffler, L.J.P., 1969, Hydrothermal alteration in Yellowstone drill hole Y-1, Upper Geyser Basin (abs.): American Geophysical Union, Transactions, v. 50, no. 4, p. 348.
White, D.E., Truesdell, A.H., and Muffler, L.J.P., 1970, Vapor-dominated hydrothermal systems (abs.): American Geophysical Union, Transactions, v. 51, p. 453.
Griscom, A., and Muffler, L.J.P., 1971, Aeromagnetic survey of the Salton Sea geothermal field, southeastern California (abs.): Geological Society of America, Abstracts with Programs, v. 3, no. 2, p. 129.
Hamilton, R.M., and Muffler, L.J.P., 1971, Microearthquakes at The Geysers, California, geothermal area (abs.): American Geophysical Union, Transactions, v. 52, p. 862.
Zohdy, A.A.R., Anderson, L.A., and Muffler, L.J.P., 1972, Resistivity, induced polarization and self-potential surveys of a vapor-dominated geothermal system (abs.): Symposium on the Electrical Parameters of Rocks, Salt Lake City, March 15–16, 1972.
Muffler, L.J.P., 1973, Current world-wide utilization and ultimate potential of geothermal energy systems (abs.): Symposium on Energy Delta--Supply vs. Demand, Science, and Technology, American Association for the Advancement of Science Meeting, San Francisco, Feb., 1974.
Muffler, L.J.P., and Bargar, K.E., 1973, Hydrothermal alteration of rhyolitic ash-flow tuff in the vapor-dominated geothermal system at Mud Volcano, Yellowstone National Park, USA (abs.): International Symposium on Water-Rock Interaction, Prague, Czechoslovakia, Abstract Vol., p. 52.
Muffler, L.J.P., 1975, Tectonic and hydrologic control of the nature and distribution of geothermal resources (abs.): Second United Nations Symposium on the Development and Use of Geothermal Resources, San Francisco, May 20–29, 1975, Abstract II-33.
Muffler, L.J.P., 1983, Scientific drilling to study the roots of active hydrothermal systems related to young magmatic intrusions (abs.): Geological Society of America, Abstracts with Programs, v. 15, no. 5, p. 434.
Muffler, L.J.P., 1986, Volcanic processes influencing development of geothermal resources (abs.): American Association of Petroleum Geologists Bulletin, v. 70, no. 7, p. 931-932 [Fourth Circum-Pacific Energy and Mineral Resources Conference, Singapore, 18–22 August, 1986].
Muffler, L.J.P., and Clynne, M.A., 1989, Geologic map of the Lassen region, Cascade Range, USA (abs.): Continental Magmatism, Abstracts, General Assembly of the International Association of Volcanology and Chemistry of the Earth's Interior, Santa Fe, New Mexico, 25 June to 01 July, 1989: New Mexico Bureau of Mines and Mineral Resources, Bulletin 131, p. 199.
Muffler, L.J.P., Clynne, M.A., and Holcomb, R.T., 1989, Late Quaternary faulting of the Hat Creek Basalt (abs.): Eos (Transactions of the American Geophysical Union), v. 70, no. 43, p. 1310.
Muffler, L.J.P., Hedenquist, J.W., Kesler, S.E., and Izawa, E., 1992, Japan-U.S. Seminar on Magmatic Contributions to Hydrothermal Systems (abs.): Eos (Transactions of the American Geophysical Union), v. 73, no. 14, Spring Meeting Supplement, p. 353.
Muffler, L.J.P., and Nathenson, Manuel, 1992, The importance of careful attention to terminology, uncertainties, and assumptions in the assessment of geothermal resources (abs.): 29th International Geological Congress, Abstracts, v. 3, p. 843.
Clynne, M.A., Muffler, L.J.P., and Christiansen, R.L., 2004, Late Quaternary volcanic units in the Lassen region of the Cascade Range: recurrence intervals and intercalation with glacial deposits (abs.): IAVCEI General Assembly, Pucón, Chile, Symposium 12b, abstract 12b_o_04.
Muffler, L.J.P., and Clynne, M.A., 2005, Overlapping calc-alkaline and tholeiitic magmatism in the southernmost Cascade Range (abs.): Geochemical Society, 15th Goldschmidt Conference, Moscow, ID, Symposium S30, Geochemistry and geochronology of the Cascade Volcanic Arc, p. A268.
Muffler, L.J.P., Clynne, M.A., Calvert, A.T., and Champion, D.E., 2008, Eruption of discrete magma batches along a normal fault zone: The Poison Lake chain, Caribou Volcanic Field, southernmost Cascades (abs.): Abstracts of Goldschmidt 2008, in Geochimica et Cosmochemica Acta, v. 72, no. 12S, p. A660.
Muffler, L.J.P., Blakely, R.J., and Clynne, M.A., 2008, Interaction of the Walker Lane and the Cascade Volcanic Arc, Northern California (abs.): American Geophysical Union, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract T23B-2032.
Muffler, L.J.P., Blakely, R.J., and Clynne, M.A., 2009, Cascade Arc and Walker Lane interaction in the Lassen volcanic region, California (abs.): Geological Society of America, Abstracts with Programs, v. 41, no. 7, p. 64.6
Muffler, L.J.P., and M.A. Clynne, 2010, Derivative products based on the Geologic Map of Lassen Volcanic National Park and Vicinity, northern California (abs.): Abstract V11C-2298 presented at 2010 Fall Meeting, AGU, San Francisco, Calif., 13–17 Dec.
Muffler, L.J.P., Champion, D.E., Calvert, A.T., and Clynne, M.A., 2012, Paleomagnetic, geochronologic, and petrologic data discriminate tholeiitic basalts of the northern Hat Creek graben, northeastern California (abs): Abstract V33B-2868 presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 03–07 Dec.
Muffler, L.J.P., Calvert, A.T., Champion, D.E., Clynne, M.A., Downs, D.T., and Christiansen, R.L., 2017. The Cascades volcanic arc between the Lassen Volcanic Center and Mount Shasta, northern California (abs.): Proceedings of IAVCEI International Scientific Assembly, Portland, Oregon, August 14–18, 2017, abstract VH13B-190, p. 731.
Champion, D.E., Downs, D.T., Muffler, L.J.P., Clynne, M.A., and Calvert, A.T., 2017, Geologic mapping of the Burney-Pit River area, California, using a multidisciplinary approach (abs): Proceedings of IAVCEI International Scientific Assembly, Portland, Oregon, August 14–18, 2017, abstract VH13B-189, p. 187.
Muffler, L.J.P., Clynne, M.A., Champion, D.E., Downs, D.T., and Calvert, A.T., 2021, Volcanic and tectonic gap between the Lassen and Shasta segments of the Cascades Volcanic Arc (abs.), Geological Society of America Abstracts with Programs. Vol. 53, No. 4, doi: 10.1130/abs/2021CD-363084
Science and Products
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government