INFRASOUND FROM HAWAIIAN TO PLINIAN ERUPTIONS: CONSTRAINING VOLCANIC SOURCE PARAMETERS A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I AT MĀNOA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN GEOLOGY AND GEOPHYSICS AUGUST 2010 By David E. Fee Dissertation Committee: Milton Garces, Chairperson Matthew Patrick Fred Duennebier Roy Wilkens Mark Merrifield ACKNOWLEDGEMENTS This body of work and degree would not be possible without the extensive help and support from many people. For the past six years Milton Garces has been my advisor, employer, and friend. I started with him and the University of Hawaii Infrasound Lab fresh out of graduate school. The next three years I was traveling around the world deploying infrasound arrays and going to conferences. It was through this experience that my interest in research and becoming a Ph.D. was reinvigorated. Milton has taught me much about infrasound and gave me the opportunity to study volcanoes, something that I have always wanted. I will always look back on my time at ISLA fondly. Also, I am not sure I would have made it through all of this sanely without lunchtime kiteboarding and surf breaks. Numerous colleagues kept me interested and on the right track along the way. Roger Waxler has been a great resource on acoustics and infrasound propagation. Curt Szuberla has answered many questions and kept things fun and interesting, and I look forward to working with him in the future at the University of Alaska Fairbanks. Darren Hart, David Green, Laslo Evers, Michael Hedlin, Kris Walker, and many others have been helpful resources and were always available for post conference beers. Doug Drob provided the G2S files and is another great source of information. Darcy Ogden has also been a great resource on volcanic jetting. Claus Hetzer has at all times been an invaluable resource on all things. The Acoustic Surveillance for Hazardous Eruptions (ASHE) project provided the impetus (and funding) for much of this work. Hugo Yepes, Patricio Ramon, and the rest of the Instituto Geofisco in Ecuador made our Tungurahua Volcano work possible, as well as being gracious hosts to our two memorable visits to Ecuador. Hank Bass and David McCormack provided some of the funding and vision for the project. Jack Seiner and Hank Bass gave me and Robin Matoza a great week-long introduction to jet noise at the University of Mississippi. Members of the Hawaiian Volcano Observatory have also been very helpful. In particular, Tim Orr, David Wilson, Paul Okubo, Rick Hobblitt, Mike Poland, Don Swanson, Jim Kauahikaua, and Matt Patrick. Matt has been a great resource, collaborator, i and friend, and I feel lucky to have worked with and have him on my committee. Frank Trusdell and Zoe Thorne have also been very gracious in hosting our array. Bernard Chouet and Phil Dawson were extremely helpful in our understanding of Kilauea. Bernard has also served as an invaluable mentor. The various employees at ISLA have made my work both enjoyable and worthwhile. James Robertson has always been there to listen when I needed to talk, and was a great travel partner. Joe Park has an immense knowledge of acoustics and science in general, and was more than glad to share it. Grace Furuya has any answer to any question, and has made my life as a student and employee much easier. Eric Pilger provided invaluable networking expertise and took quite a lot of stress off me. A big thanks to the rest of my committee, Fred Duennebier, Roy Wilkens, and Mark Merrifield, for helping me along the way and being great resources on academia and science in general. Andy Harris briefly served on my committee and pointed me the right way on a number of topics. Chapter 2 will soon be submitted to Geophysical Research Letters. Chapter 3 is currently in review as: Fee, D., M. Garces, M. Patrick, B. Chouet, P. Dawson, and D. Swanson (in review), Infrasonic Harmonic Tremor and Degassing Bursts from Halema`uma`u Crater, Kilauea, Journal of Geophysical Research-Solid Earth. Chapter 4 is published in full as: Fee, D., M. Garces, and A. Steffke (2010), Infrasound from Tungurahua Volcano 2006–2008: Strombolian to Plinian eruptive activity, Journal of Volcanology and Geothermal Research, 193, 67-81. Chapter 5 is currently being published in full as: Fee, D., A. Steffke, and M. Garces (in press), Characterization of the 2008 Kasatochi and Okmok eruptions using remote infrasound arrays Journal of Geophysical Research-Atmospheres. Financial support was provided by NSF grant EAR- 0609669 and NOAA via University of Mississippi subcontract 09-09-022. Other co- authored papers of mine are mentioned in the subsequent chapters. A huge thanks to all coauthors on all papers, none of it would have been possible without their help. Robin Matoza and Andrea Steffke have both been more than just great collaborators. Due to my unique graduate student situation away from the UH campus, Andrea gave me a great deal of insight on what is required of students. I would not have been able to graduate without her. She also taught me a lot about remote sensing, quite a ii feat considering I started from not knowing anything. I met Robin when he was just beginning as a graduate student, and we hit it off right away. As he (and I) progressed along our academic paths, our mutual interest for science, infrasound, and volcanoes kept us in touch often. His knowledge, collaboration, and encouragement has made anything I have been involved with that much better. Further, many of my life’s concerns have been dealt with over a beer (or email) with Robin. Above all I feel that I have made two lasting friends. Lastly, I want to thank my family. As long as I can remember, my parents and sister have been supportive of my endeavors, and this is time is no different. Whenever I was feeling stressed or overworked my family knew just the right thing to say to help me get through it. I feel blessed to have such an amazing family. Finally, I am extraordinarily grateful to my wonderful wife Elizabeth. We started our journey together roughly the same time as I started my Ph.D., and she has put up with all my late nights and often hectic schedule without a complaint. Her unwavering support, interest, and love have made this all possible. iii ABSTRACT Volcanoes produce a diversity of acoustic signals that may propagate thousands of kilometers through the atmosphere. These signals are indicative of the volcano’s eruption style and dynamics. This dissertation details the diverse infrasound from four volcanoes: Kilauea, Hawaii; Tungurahua, Ecuador; and Okmok and Kasatochi, Alaska. I demonstrate the ability to constrain eruption source parameters, such as location, onset, duration, intensity, and escalation, by combining infrasound and other geophysical techniques. Kilauea Volcano produced two unexpected fissure eruptions in 2007 that varied spatially and temporally. Infrasound was the first technology to detect the 19 June fissure eruption. Changes in the infrasonic source azimuth from the 21 July fissure eruption are used to infer rupture timing of individual fissure segments. In 2008 activity returned to Halema’uma’u Crater, Kilauea after a 25 year hiatus. Numerous degassing bursts produced infrasound, including the initial vent-clearing event. Near-continuous harmonic tremor followed the initial burst. The harmonic tremor and degassing burst signatures are consistent with a process which excites a steam-filled cavity overlying the magma surface into Helmholtz and acoustic resonance. Between 2006-2008, Tungurahua Volcano produced over 20,000 transient explosions and numerous sustained explosive eruptions. The spectrum of the sustained eruptions is recurrent, readily recognizable, and indicative of volcanic jetting and significant atmospheric ash injection. Broadband, sustained low-frequency (<0.5 Hz) infrasound appears to be indicative of stratospheric emissions. This work has direct civil defense application in providing notifications of ash injection into the atmosphere. Using iv previous eruptions as case studies, an automatic detection system was designed and successfully notified aviation authorities of the onset, escalation, and cessation of a hazardous February 2008 eruption within 6 minutes. The 2008 Plinian eruptions of Okmok and Kasatochi produced stratospheric ash clouds and infrasound focused below 0.5 Hz that was detected thousands of kilometers away. Ray tracing and parabolic equation modeling are performed to determine the propagation path, travel time, and attenuation for the eruptions. The long-range infrasound from Kasatochi displays a characteristic jet noise-like spectrum regardless of ash content. Future detailed volcano infrasound studies will assist in hazard mitigation, and could advance the understanding of volcanic processes and acoustic propagation considerably. v TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................................................................................. i ABSTRACT ....................................................................................................................... iv LIST OF TABLES ............................................................................................................. ix LIST OF FIGURES ............................................................................................................ x CHAPTER 1: INTRODUCTION .................................................................................... 1 1.1 Infrasound Background ................................................................................................