Abstract Joyner, Catelyn Nichole
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ABSTRACT JOYNER, CATELYN NICHOLE. Lacustrine Megaturbidites and Displacement Waves: The Holocene Earthquake History of the Lake Creek-Boundary Creek Fault at Lake Crescent, Washington, USA. (Under the direction of Dr. Karl Wegmann and Dr. Elana Leithold). Lake Crescent is a deep, glacially carved lake located on the northern Olympic Peninsula within Olympic National Park. Its location in the forearc of the Cascadia subduction zone and proximity to seismically-active regional crustal faults allow for its high resolution sedimentary record to function as an extension of the local paleoseismic record. This study uses airborne lidar topography, multibeam bathymetry, seismic reflection profiles, and sediment cores to characterize four megaturbidites attributed to Holocene ruptures along the Lake Creek-Boundary Creek fault. The megaturbidites each consist of an erosively based normally graded basaltic sand layer overlain in turn by massive, homogenous silt with plant debris, a clay cap, and interstratified chloritic clay and basaltic sand laminae. The deposits can be traced across the deep basins of the 20 km2 lake and exceed 1.3 m in thickness in cores recovered from the deepest part of the lake. The youngest megaturbidite is estimated to have a minimum volume of ~4.8 x 106 m3. Petrologic analysis of megaturbidite basal sands indicates that they are sourced from the entire lake margin and likely were remobilized from shallow subaqueous environments. Newly acquired bathymetric data reveal that several large rockslides that surround Lake Crescent deposited debris into the lake. Previous research indicates that subaerial rockslides entering lakes can generate displacement (tsunami) waves and seiches that result in megaturbidite deposits. Radiocarbon analysis of the megaturbidites indicate that four rockslide-displacement waves occurred at 2,859 (2,785-2,943), 4,015 (3,921-4,088), 5,736 (5,656-5,889), and 7,097 (7,006-7,242) cal yr BP. The most recent event deposited ~7 x 106 m3 of debris into the lake, which likely generated a displacement wave with an opposite- shore run up height of 86 ± 20 m. Offset of the megaturbidite layers visible in seismic reflection profiles where the Lake Creek-Boundary Creek fault traverses the northern lake basin shows that rupture along the fault and the deposition of megaturbidites are related. The mean inter-event recurrence interval for the four Lake Crescent megaturbidites is 1412 ± 234 years with the mean age of the most recent event 2,859 cal yr BP. As a result, based upon a lognormal probability distribution there is a 28% chance that an earthquake will occur along the Lake Crescent portion of the Lake Creek-Boundary Creek fault zone in the next 50 years. This result highlights the regional seismic hazard to the north Olympic Peninsula posed by this fault. © Copyright 2016 by Catelyn Nichole Joyner All Rights Reserved Lacustrine Megaturbidites and Displacement Waves: The Holocene Earthquake History of the Lake Creek-Boundary Creek Fault at Lake Crescent, Washington, USA by Catelyn Nichole Joyner A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Science Marine, Earth, and Atmospheric Sciences Raleigh, North Carolina 2016 APPROVED BY: _______________________________ _______________________________ Dr. Karl Wegmann Dr. Elana Leithold Co-Chair of Advisory Committee Co-Chair of Advisory Committee _______________________________ Dr. DelWayne Bohnenstiehl DEDICATION For Mom and Dad- You always told me I could achieve my dreams. Thank you for the eternal support that allowed me to chase them. Dad, I hope this gets me a job. Mom, thanks for being my best friend through it all. For Vanessa- I am ever grateful for the patience and support you have provided over the years. You never once complained all the time I talked about rocks. This wouldn’t have been possible without you. For Granny- I miss you and I hope you are proud of me. For Alex (Alchy) and Wesley (Bubs)- Alchy, you are my rock. For Aunt Rhonda, Uncle Tom, and Jordan- Aunt Rhonda, you always have had my back and encouraged my rock collecting at a young age. You are such a bright part of my life; much like your favorite mineral, mica. I would not have made it without football chili Sundays and complaining about the Washington Redskins with you Uncle Tom. For Nanny and Papa- You are the best grandparents anyone could ask for. The great talks and even better food (thanks Nanny) I enjoyed while visiting home were a much appreciated break from school. For Aunt Linda, Uncle Eddie, and Slim- Aunt Linda, no matter the situation, you always make me laugh- something that I truly valued on the hard days. Uncle Eddie and Slim, our fishing days on the river provided much relief from school and I will always remember them. Also, thank you to my dogs Portia and Ellen for your endless love and attention on the good and bad days. Thank you to everyone who stepped up and helped Mom when she was sick when I couldn’t while I was in Raleigh working on this thesis. I love you all! ii BIOGRAPHY I was born on November 6, 1991, to Chip and Janine Joyner of Suffolk, Virginia. During high school, I pursued an Associate degree in science where I was the youngest student to attend Paul D. Camp Community College at age 15. It was during this time that I discovered my love for math and science related courses which landed me at North Carolina State University in 2010 as a freshman with a degree already in hand. Initially, I had an incredibly hard time figuring out what major I wanted to pursue but my love of math, science, and the outdoors pushed me into the world of geology. In 2011, I became the research assistant in the geology labs at the North Carolina State Museum of Natural Science. This opportunity provided research and professional development opportunities that allowed me to excel as a student leading to my graduation in 2013. My amazing experience as an undergraduate in the Marine, Earth, and Atmospheric Science Department as well as undying love for the Wolfpack brought me back to NCSU for my graduate studies in 2014. iii ACKNOWLEDGMENTS First and foremost, thank you to all of my committee members. Dr. Karl Wegmann, thank you for the support and encouragement as well as letting me work on such an exciting project. Dr. Elana Leithold, thank you for infectious enthusiasm about sedimentology and inspiring me to want to work with sediments when I was an undergraduate. Dr. DelWayne Bohnenstiehl, thank you for your patience and support while I learned about data analysis and the complex language of Matlab. Thank you all for trusting me to work with you. My relationships with you all have encouraged me become a better student, collaborator, and geologist. Thank you to the Earth Surface Processes Research Group: Rachel Atkins, Gantulga Bayasgalan, Adam Lee, Audrianna Pollen, John Wall, Steve Smith, and Julian (Nuttman) Chesnutt for their academic feedback and great friendship. Thank you to undergraduates Austin Jacobs, Nicholas Lavoie, and Hallie Nunamaker for their diligence and help with the Lake Crescent sand petrology project. Thank you to Nicholas Lavoie, Bryce Finch, and Alex Ruley for their help with the particle size analysis. Thanks also go to Dr. Ronald Fodor for helping me understand the world of petrology again after a 5-year hiatus. A very special thank you goes to Dr. Christopher Tacker, who took a chance and hired me while I was an undergraduate. Thank you for letting me work in your lab for my thesis research- what a great mentor and friend you have been. iv Thank you so much to the team from LacCore- Kristina Brady, Anders Noren, Mark Shapley, and Ryan O’Grady. Learning from you all in the field and lab was an amazing experience! Last but not least, thank you to all other friends in the MEAS Department for all the good times and memories! This research was made possible by a U.S. Geological Survey – National Earthquake Hazards Reduction Program Grant (Award #G15AP00091). Research within Olympic National Park was conducted under Special Use Permit #OLYM-366. v TABLE OF CONTENTS LIST OF TABLES ........................................................................................................... ix LIST OF FIGURES ...........................................................................................................x LIST OF APPENDICES ................................................................................................. xi 1.0 INTRODUCTION........................................................................................................1 1.1 Geologic Setting...............................................................................................4 1.2 Tectonic Setting and Earthquake History ........................................................5 1.3 Lake Crescent Catchment ..............................................................................10 2.0 METHODS .................................................................................................................12 2.1 Seismic Reflection Survey ...............................................................................12 2.2 Sediment Coring ..............................................................................................12 2.3 Multibeam Bathymetric Survey .......................................................................13 2.4 Core Sampling .................................................................................................13