United States Department of the Interior Geological Survey Proceedings of Workshop Xix Active Tectonic and Magmatic Processes Be
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UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY PROCEEDINGS OF WORKSHOP XIX ACTIVE TECTONIC AND MAGMATIC PROCESSES BENEATH LONG VALLEY CALDERA, EASTERN CALIFORNIA VOLUME I 24 - 27 January 1984 Sponsored by U.S. GEOLOGICAL SURVEY VOLCANO HAZARDS PROGRAM Editors and Convenors David P. Hill U.S. Geological Survey Menlo Park, California 94025 Roy A. Bailey U.S. Geological Survey Menlo Park, California 94025 Allan S. Ryall University of Nevada Reno, Nevada 89557-0018 OPEN-FILE REPORT 84-939 Compiled by Muriel Jacobson This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Any use of trade names is for descriptive purposes only and does not imply endorsement by the USGS. MENLO PARK, CALIFORNIA 1984 CONFERENCES TO DATE Conference I Abnormal Animal Behavior Prior to Earthquakes, I Not Open-Filed Conference II Experimental Studies of Rock Friction with Application to Earthquake Prediction Not Open-Filed Conference III Fault Mechanics and Its Relation to Earthquake Prediction Open-File No. 78-380 Conference IV Use of Volunteers in the Earthquake Hazards Reduction Program Open-File No. 78-336 Conference V Communicating Earthquake Hazard Reduction Information Open-File No. 78-933 Conference VI Methodology for Identifying Seismic Gaps and Soon-to-Break Gaps Open-File No. 78-943 Conference VII Stress and Strain Measurements Related to Earthquake Prediction Open-File No. 79-370 Conference VIII Analysis of Actual Fault Zones in Bedrock Open-File No. 79-1239 Conference IX Magnitude of Deviatoric Stresses in the Earth's Crust and Upper Mantle Open-File No. 80-625 Conference X Earthquake Hazards Along the Wasatch and Sierra-Nevada Frontal Fault Zones Open-File No. 80-801 Conference XI Abnormal Animal Behavior Prior to Earthquakes, II Open-File No. 80-453 Conference XII Earthquake Prediction Information Open-File No. 80-843 Conference XIII Evaluation of Regional Seismic Hazards and Risk Open-File No. 81-437 Open-File Service Section Branch of Distribution U.S. Geological Survey Box 25425, Federal Center Denver, Colorado 80225 CONFERENCES TO DATE Workshop XV Preparing for and Responding to a Damaging Earthquake in the Eastern United States Open-File No. 82-220 Workshop XVI The Dynamic Characteristics of Faulting Inferred from Recordings of Strong Ground Motion Open-File No. 82-591 Workshop XVII Hydraulic Fracturing Stress Measurements Open-File No. 82-1075 Workshop XVIII Continuing Actions to Reduce Losses from Earthquakes in the Mississippi Valley Area Open-File No. 83-157 Workshop XIX Active Tectonic and Magmatic Processes Beneath Long Valley Caldera, Eastern California Open-File No. 84-939 Workshop XX The 1886 Charleston, South Carolina, Earthquake and its Implications for Today Open-File No. 83-843 Workshop XXI A Workshop on "Continuing Actions To Reduce Potential Losses from Future Earthquakes in the Northeastern United States" Open-File No. 83-844 Workshop XXII A Workshop on "Site-Specific Effects of Soil and Rock on Ground Motion and the Implications for Earthquake-Resistant Design" Open-File No. 83-845 Workshop XXIII A Workshop on "Continuing Actions to Reduce Potential Losses from Future Earthquakes in Arkansas and Nearby States" Open-File No. 83-846 Workshop XXIV A Workshop on "Geologic Hazards in Puerto Rico" Open-File No. 84-761 Workshop XXV A Workshop on "Earthquakes Hazards in the Virgin Island Region" Open-File No. 84-762 Workshop XXVI A Workshop on "Evaluating the Regional and Urban Earthquakes Hazards in Utah" Open-File No. 84-763 Open-File Service Section Branch of Distribution U.S. Geological Survey Box 25425, Federal Center Denver, Colorado 80225 TABLE OF CONTENTS VOLUME I Acknowledgements........................................................... 1 List of Participants....................................................... 2 Summary Active Tectonic and Magmatic Processes Beneath Long Valley Caldera, Easthern California David P. Hill, Alan S. Ryall, and Roy A. Bailey.................. 4 GEOLOGY Chemical Evolution and Current State of the Long Valley Magma Chamber Roy A. Bailey.................................................... 24 Eruptive History of Glass Mountain, Long Valley California: Precursors to a Large Explosive Eruption Jenny Metz and Gail Mahood....................................... 41 Holocene Eruptions at the Inyo Volcanic Chain, California Implications for Possible Eruptions in Long Valley Caldera C. Dan Miller.................................................... 76 Most Recent Eruptions of the Mono Craters, Eastern Central California Kerry E. Sieh.................................................... 96 Igneous Dikes at Long Valley, CA: Emplacement Mechanisms and Associated Geologic Structures David D. Pollard, Johnathan H. Fink, and Paul T. Delaney......... 130 Degassing of Magma in an Obsidian Flow and Inferred Degassing Behavior at Depth J. C. Eichelberger and H. R. Westrich............................ 147 GEOPHYSICS Constraints on the Upper Crustral Structure of the Long Valley - Mono Craters Volcanic Complex, Eastern California from Seismic Refraction Measurements David P. Hill, Edy Kissling, James H. Luetgert, and Urs Kradolfer.................................................... 151 Three-Dimensional Structure of the Long Valley Caldera, California, Region by Geotomography Edy Kissling, William L. Ellsworth, and R. S. Cockerham.......... 188 Location and Configuration of Magma Bodies Beneath Long Valley, California, Determined from Anomalous Earthquake Signals Chris 0. Sanders................................................. 221 Gravity Investigations at Long Valley Caldera, California Robert C. Jachens and Carter W. Roberts.......................... 248 Gravity Variations in the Mammoth Lakes, Mono Lake and Owens Valley, California Regions J. H. Whitcomb and J. B. Rundle.................................. 280 The Long Valley / Mono Craters Volcanic Complex; a Preliminary Interpretation Based on Telluric Field Patterns John F. Hermance, Warren Slocum, and Gregory A. Neumann.......... 281 Earthquake Processes in the Long Valley Area, California Bruce R. Julian and Stuart Sipkin................................ 319 Dynamics of an Expanding Fluid-filled Crack Bernard Chouet and Bruce R. Julian............................... 367 A Re-examination of the Moment Tensor solution of the 1980 Mammoth Lake Earthquakes Terry C. Wallace................................................. 409 Relationship Between Aftershock Locations and Mechamisms of the May, 1980, Mammoth Lakes Earthquakes Chester S. Lide and Alan S. Ryall................................ 440 Focal Mechamisms and Crustral Stress Patterns in the Mammoth Lakes Area Uta R. Vetter.................................................... 453 Three Different Mechamisms for Elongate Distribution of Shallow Earthquake Epicenters Kazuaki Nakamura................................................. 482 RECENT ACTIVITY VOLUME II Seismic Activity in Long Valley Caldera Area, California: June 1982 Through July 1984 R. S. Cockerham and A. M. Pitt................................... 493 High-Resolution Microseismicity Study of Possible Magmatic Intrusion in the Long Valley Caldera Albert T. Smith.................................................. 527 Earthquake Swarm in Long Valley Caldera, California, January 1983: Evidence for Dike Injection J. C. Savage and R. S. Cockerham................................. 541 ii A Model for Deformation in Long Valley, California, 1980-1983 John B. Rundle and James A. Whitcomb............................. 584 THE GEOTHERMAL SYSTEM Evolution and Present State of the Hydrothermal System in Long Valley Caldera Micheal L. Sorey................................................. 617 A Transient Model of the Geothermal System of the Long Valley Caldera, California David D. Blackwell............................................... 659 Soil Hg and Rn Distribution Pattern at Long Valley Caldera, Eastern California Stanley N. Williams and Kenneth W. Hudnut........................ 708 RELATED MAGMATIC SYSTEMS Historical Unrest at Large Quaternary Calderas of the World C. G. Newhall, D. Dzurisin, and L. S. Mullineaux................. 714 Postcaldera Evolution and Current Activity of the Yellowstone Caldera Robert L. Christiansen........................................... 743 Recent Ground Deformation and Seismicity at Long Valley (California), Yellowstone (Wyoming), the Phlegrean Fields (Italy), and Rabaul (Papua New Guinea) D. Dzurisin and C. G. Newhall.................................... 784 Implications of Silicic Vent Patterns for the Presence of Large Crustral Magma Chambers Charles R. Bacon................................................. 830 Structure of the Tertiary Questa Caldera, New Mexico an Eroded Analog for Current Activity at Long Valley Peter W. Lipman.................................................. 851 A Note on Links Between Magma-Tectonic Rate-Balances, Plutonism and Volcanism Herbert R. Shaw.................................................. 886 ni ACKNOWLEDGEMENTS This conference was sponsored by the U.S. Geological Survey under the Volcano Hazards Program. The initial suggestion for holding a "Redbook" conference on current activity in Long Valley caldera came from Bill Ellsworth. Both he and Patrick Muffler provided unfailing encouragement and support for this endeavor from start to finish. Wanda Seiders arranged the transportation and accomodations for the conference as well as the many logistical details that permitted the participants