GLOBAL POSITIONING SYSTEM MEASUREMENT OF CRUSTAL DEFORMATION IN CENTRAL CALIFORNIA by MARK HUNTER MURRAY B.S., Geophysics Massachusetts Institute of Technology (1982) SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY and the WOODS HOLE OCEANOGRAPHIC INSTITUTION June 1991 © Massachusetts Institute of Technology, 1991 Signature of Author I / - in Oceanography Massachusetts Institute of Tec OceanographicpologyJ-ecds'ýole Institution Certified by Thomas H. Jordan Thesis Supervisor Accepted by A George P. Lohmann Chairman, Joint Committee for Marine Geology and Geophysics, Massachusetts Institute of Technology/Woods Hole Oceanographic Institution ARCHIVES GLOBAL POSITIONING SYSTEM MEASUREMENT OF CRUSTAL DEFORMATION IN CENTRAL CALIFORNIA by MARK HUNTER MURRAY Submitted to the Department of Earth, Atmospheric, and Planetary Sciences on July 24, 1991 in partial fulfillment of the requirements for the Degree of Doctor of Philosophy ABSTRACT In Chapter 2, we develop a conventional terrestrial reference frame-designated SV6--for the analysis of Global Positioning System (GPS) observations. The reference frame adopts the geocentric origin and scale defined by eleven years of satellite laser ranging (SLR) observations. The precise relative locations of 80 sites that primarily realize the SV6 frame are derived from very-long-baseline interferometry (VLBI) observations. The orientation is consistent with the International Earth Rotation Service terrestrial reference system. The coordinates of sixteen sites with well-determined local vector ties between collocated VLBI and SLR reference points are used to make the VLBI coordinate system commensurate with the SLR system; the sites are globally distributed, including nine in North America, three in Europe, and one each in China, Australia, Hawaii, and Kwajalein. A scales of the VLBI and SLR systems differ by 4±1 parts in 109. SV6 includes estimates of the temporal evolution and uncertainties of the coordinates from VLBI and geophysical observations and we develop a methodology for systematically combining temporally heterogeneous space-geodetic observations with geophysical and geological information, such as global plate tectonic motion models. In Chapter 3, we present estimates of crustal deformation in central California from thirteen GPS campaigns, conducted primarily by a consortium of four universities from December 1986 to February 1991. Each major campaign occupied a network of seven to twenty sites in California repeatedly for four to five days, with additional fiduciary control provided by sites distributed across North America, and in Hawaii and Europe. The precision of the estimated baseline vectors, based on the day-to-day scatter over each campaign, is 3-5 mm in the horizontal components with 1-3x10-8 dependence on baseline length for well-designed experiments. The precision in the vertical is 15-25 mm. Precision is most strongly affected by changes to the fiducial network and ionospheric conditions. Systematic constant error sources may be responsible for a slight increase in long-term scatter over short-term scatter. We then estimate relative motion between twelve sites in California that have observations spanning 1.5-4.2 years. with uncertainties at the 1-1.5 mm/yr level. Confidence in some of the estimated rates is limited by apparent inconsistencies between experiments with poor fiducial control. The estimated relative motions of Owens Valley and Palos Verdes with respect to Vandenberg are consistent with VLBI-derived rates. We estimate north-south convergence across the eastern Santa Barbara channel at 5.2 mm/yr, and our results are consistent with a change to left-lateral shear in the central Santa Barbara channel. The estimated deformation across the Santa Maria fold and thrust belt has less convergence and more right-lateral shear than had been previously estimated from triangulation and trilateration measurements. The relative motion of six sites along the western margin in the vicinity of Vandenberg are consistent with 2-4 mm/yr motion on the Hosgri fault. Relative motion east of the San Andreas suggests that an additional 2-4 mm/yr motion may be accommodated within a shear zone located in Owens Valley and the Mojave Desert. Thesis supervisor: Thomas H. Jordan, Professor of Geophysics ACKNOWLEDGMENTS My early attempts to become a physicist at M.I.T. many years ago required a great deal of consoling, late-night pool games, and trips to Steve's Ice Cream. I would like to thank, in particular, Aaron and Denise Bobick, Kevin Damon, Christopher Dorn, and Ray Sepe for somehow keeping me sane. The highlight of my undergraduate career was the time I spent in the California desert and pool halls and saloons of Las Vegas with Peter Molnar, Dave Olgaard, and my fellow Field Geophysics classmates-especially Joann Stock, Andy Michael, Isabel Brome, and Tanner Wray. Sean Solomon introduced me to the joys of geophysics and was gracious enough to keep me employed when I had no idea what I wanted to do. I am in the Joint Program today because of the cruise we took on the R/V Knorr, where I shared some memorable times with Mike Purdy, Bob Dietrich, Peter Roberts, and Doug Toomey. My ocean-going career was scuttled, however, when Tom Jordan convinced me that space-geodetic techniques could be really fundamental. His great intuition into scientific problems and cogent advice continue to be an inspiration. A special thanks to Robin Jordan for her dear friendship and consideration over the years and to Alexandra for teaching me a thing or two about dancing. My knowledge of space-based geodesy would be considerably poorer without the kind and patient guidance of Bob King. I have also profited from many useful discussions with Bernard Minster, Jim Davis, Yehuda Bock, Peter Morgan, Jim Ray, Irwin Shapiro, and Tom Herring. It has been my great pleasure and fortune to work with Kurt Feigl and Da-nan Dong, who kept everything running smoothly while I supposedly worked on my thesis. The large amount of data considered in this thesis would not have been possible without the dedicated efforts of the other members of the SCUM Consortium, for which I thank Duncan Agnew, Brad Hager, Dave Jackson, and especially those who did all the work, Frank Webb, Kristine Larson, Andrea Donnellan, and Shawn Larsen, among others. I am grateful for the support provided by a NASA Graduate Student Researchers Program fellowship. The work in this thesis vas partially funded by NASA giants NAG5-459 and NAG5-737, and NSF grant EAR-8618513. I will miss most the camaraderie and esprit de corps of the many other graduate students I have known during my long tenure here. Roger Buck, Sharon Quayle, Scott Phillips, and Darby Dyar made living on Magnolia Avenue an immense and unrepeatable pleasure. Lynn Hall and Rick Buxton provided many a fine meal and shared their love of movies. Other elder graduate students who provided much inspiration and laughs include Kaye Shedlock, Steve Bratt, Steve Park, Craig Jones, Mike Nelson, Kiyoshi Yomagida, Paul Okubo, and Paul Huang. To my penecontemporaneous colleagues-some long since departed, some soon to follow-a hearty salute! These include Beth Robinson, Karen Fischer, Jeanne Sauber, Steve Hickman, Sarah Kruse, Anne Sheehan, Will Wilcock, Matt Cordery, Paul Filmer, and Mike Bergman. Living next to Mass Ave. was made bearable by the inimitable Eugene Lavely and Richard Holme, to whom I shall always wish a nice day. I deeply regret not being able to enjoy further the company of those that follow me, including Peter Puster, Noriyuki Namiki, Pat McGovern, Paolo Harabaglia, Pierre Ihmle, Mark Simons, Steve Shapiro, Jim Gaherty, Deb Zervas, Dawn Sumner, Paula Waschbusch, Peter Kaufman, and Garrett Ito. My fondest regards are reserved for those with whom I have shared the most: to Bob Grimm for being Bobhead, to Justin Revenaugh for his irreverant humor and remarkable keyboard magic, to Greg Beroza for his irrepressible humor and scientific 61an and to Eva Huala for somehow putting up with it all. A special thanks to Lind Gee for cookies, rubber band practice, and an affectionate friendship that helped me through the difficult times. Lastly, I would like to thank my mother and father and sisters for their patience, understanding, and love throughout this long journey: it's time I came back to the West Coast. TABLE OF CONTENTS Abstract ................................................. 3 Acknowledgments .................................................................................................................. 5 Table of Contents .................................................................................................................. 7 Chapter 1. Introduction ........................................................................................................ 11 Terrestrial Geodesy and the San Andreas Fault ........................................................ 11 Satellite Geodesy and Plate Tectonics ...................................................................... 17 Space Geodesy and the San Andreas Discrepancy ................................................... 25 The Global Positioning System and Deformation in California ..................... 32 Thesis Plan ................................................................................................................ 37 Chapter 2. SV6: A Terrestrial Reference Frame for the Global Positioning Sysiemrn........... 41 Introduction