Old Dominion University ODU Digital Commons Physics Theses & Dissertations Physics Summer 2012 Modeling, Visualizing, and Understanding Complex Tectonic Structures on the Surface and in the Sub-Surface Steven Wild Old Dominion University Follow this and additional works at: https://digitalcommons.odu.edu/physics_etds Part of the Geophysics and Seismology Commons, and the Tectonics and Structure Commons Recommended Citation Wild, Steven. "Modeling, Visualizing, and Understanding Complex Tectonic Structures on the Surface and in the Sub-Surface" (2012). Doctor of Philosophy (PhD), dissertation, Physics, Old Dominion University, DOI: 10.25777/t010-ne93 https://digitalcommons.odu.edu/physics_etds/96 This Dissertation is brought to you for free and open access by the Physics at ODU Digital Commons. It has been accepted for inclusion in Physics Theses & Dissertations by an authorized administrator of ODU Digital Commons. For more information, please contact [email protected]. MODELING, VISUALIZING, AND UNDERSTANDING COMPLEX TECTONIC STRUCTURES ON THE SURFACE AND IN THE SUB-SURFACE by Steven Wild B.S. Physics June 1996, Baldwin-Wallace College M.S. Chemistry June 2000, Indiana University M.S. Physics June 2009, Old Dominion University A Dissertation Submitted to the Faculty of Old Dominion University in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY PHYSICS OLD DOMINION UNIVERSITY August 2012 Approved by; Declan De Paor (Co-Director) ABSTRACT MODELING, VISUALIZING, AND UNDERSTANDING COMPLEX TECTONIC STRUCTURES ON THE SURFACE AND IN THE SUB-SURFACE Steven Wild Old Dominion University, 2012 Co-Directors: Dr. Declan De Paor Dr. Jennifer Georgen Plate tectonics is a relatively new theory with many details of plate dynamics which remain to be worked out. Moving plates can interact by divergence, lateral sliding, convergence, or collision. At a convergent plate boundary, a lithospheric slab of oceanic crust and upper mantle is subducted at a trench and dips down under a magmatic arc - either oceanic or continental. Textbooks show a static view of conver­ gent boundaries but plate dynamics require that subduction zones and magmatic arcs must migrate with time. Therefore I develop animated models to help convey this motion. Also, convergent plate boundaries cannot continue along strike or down dip indefinitely without changing. Subduction zones change orientation and eventually terminate. They may bend and shear or tear and open a window for asthenospheric flow. Two different convergent plate boundaries are the primary focus of my studies: the Tonga subduction zone where the Pacific plate moving beneath an island arc is torn along the Samoan Island Archipelago, and the Andean subduction zone in central South America where the Nazca plate moves beneath a continental arc. I choose these zones because they exhibit tears or shears, where subduction stops, or changes dip suddenly. To examine these features I use several modeling and visual­ ization techniques. COLLADA (COLLabrative Design Activity) models in Google Earth and Google Earth Application Programming Interface (API) are used for vi­ sualizing and teaching of plate boundary systems. The testing of COLLADA models for geoscience concepts showed positive learning gains. Kinematic models are made to study strain rates and possible methods of plate evolution. Dynamic COMSOL numerical models are created to probe temperature and flow fields in the subduction zone. Animated COLLADA models are designed for different models of subduction initiation and development for the Tonga trench for both research and educational purposes. The development of these models led to a new hypothesis of this region's formation. Using these models and Google Earth materials studies in undergraduate classes tested the effectiveness of Google Earth based lab activities for enhancing student understanding of geoscience. In the central Andean subduction zone, emergent COLLADA models are made from mining GeoMapApp (http://www.geomapapp.org) and published contour data to demonstrate the unique geometry of the Nazca plate having adjacent subduction angles of 10° and 30°. This led to the research question, can the Nazca plate sup­ port this geometry by shearing without tearing? A literature review shows efforts to explore this topic by means of hypocenter, teleseismic, and thermal data to have no consensus on the topic. To this end a new approach is taken to examine this region by applying the methods of kinematic and dynamic modeling to further explore this question. These different models of the Andean system lead to the conclusion that no major magmatic window could have opened between the flat and steep subduction areas given the time and deformation mechanisms available. iv ACKNOWLEDGMENTS I would first like to thank my thesis committee members, especially Dr. Declan De Paor and Dr. Jennifer Georgen who gave many hours of their time to help me along in my graduate career. I also want to thank Dr. Georgen for allowing me to use her computer and software for the simulation work. I would also like to thank Dr. De Paor for allowing me to attend many conferences and events to enrich my graduate experience. I want to thank my wife, Alisha, for all her love and support. My research was supported in part by National Science Foundation (NSF) CCLI 0837040, NSF TUES 1022755, NSF GEO 1034643, and a Google Faculty Research Award. Any opinions, findings, and conclusions or recommendations expressed in this thesis are those of the author and do not necessarily reflect the views of the National Science Foundation or Google Inc. I benefited from collaborations with Steve Whitmeyer, John Bailey, and Richard Treves, and NSF independent assessor Janice Gobert. V TABLE OF CONTENTS Page LIST OF TABLES viii LIST OF FIGURES xviii Chapter 1. INTRODUCTION 1 1.1 KINEMATIC AND DYNAMIC MODELS 2 1.2 VISUALIZATIONS AND EDUCATIONAL STUDIES 3 2. EMERGENT AND ANIMATED COLLADA MODELS OF THE TONGA TRENCH AND SAMOA ARCHIPELAGO: IMPLICATIONS FOR GEO- SCIENCE MODELING, EDUCATION, AND RESEARCH 5 2.1 ABSTRACT 5 2.2 INTRODUCTION 6 2.3 GEOLOGICAL BACKGROUND 8 2.4 COLLADA MODELS IN THE GOOGLE EARTH DESKTOP APP . 16 2.5 THE GOOGLE EARTH API AND JAVASCRIPT CONTROLS ... 21 2.6 IMPLEMENTATION 23 2.7 ENHANCED VISUALIZATION USING GOOGLE MARS 23 2.8 TECTONIC MODELS OF THE TONGA REGION 29 2.9 DISCUSSION AND CONCLUSIONS 42 3. TESTING GEOSCIENCE LEARNING WITH GOOGLE EARTH 44 3.1 ABSTRACT 44 3.2 INTRODUCTION 45 3.3 RATIONALE 49 3.4 STUDY 1 50 3.5 STUDY 2 59 3.6 DISCUSSION 68 4. AVATARS AND MULTI-STUDENT INTERACTIONS IN GOOGLE EARTH - BASED VIRTUAL FIELD EXPERIENCES 75 4.1 ABSTRACT 75 4.2 INTRODUCTION 76 4.3 WEB-CHAT EXAMPLE USING AJAX AND PHP 77 4.4 PASSING OTHER DATA: AVATAR MOVEMENT 82 4.5 DATA TRAFFIC 85 4.6 DATA-LOGGING 86 4.7 CONCLUSIONS 87 vi 5. KINEMATIC AND STRAIN MODELING 89 5.1 ABSTRACT 89 5.2 INTRODUCTION 90 5.3 THE ANDEAN OROGEN 90 5.4 3D VISUALIZATION 96 5.5 TRANSITION ZONES - TORN OR SHEARED? 102 5.6 REFERENCE FRAMES 105 5.7 REGIONS 105 5.8 BASIC CALCULATIONS FOR TEAR 107 5.9 THE SHEAR ALTERNATIVE 110 5.10 DISPLACEMENT AND STRAIN MODELING Ill 5.11 SLAB THICKNESS IN A SIMPLE SHEAR ZONE 113 5.12 DUCTILE DEFORMATION MECHANISMS 118 5.13 DISCUSSION AND CONCLUSIONS 120 6. 2D NUMERICAL MODELING OF SUBDUCTION ZONES 121 6.1 ABSTRACT 121 6.2 INTRODUCTION 122 6.3 GEOGRAPHICAL AREA 123 6.4 NUMERICAL MODEL 126 6.5 PARAMETER SPACE 131 6.6 QUANTIFICATION OF MODEL RESULTS 133 6.7 RESULTS AND DISCUSSION 134 6.8 CONCLUSIONS 155 7. 3D NUMERICAL MODELS 156 7.1 ABSTRACT 156 7.2 INTRODUCTION 157 7.3 DESIGN OF 3D MODEL AND NUMERICAL METHODOLOGY . 157 7.4 BRITTLE-DUCTILE TRANSITION TEMPERATURE 159 7.5 RESULTS AND DISCUSSION 163 7.6 CONCLUSIONS 180 8. CONCLUSIONS 181 BIBLIOGRAPHY 183 APPENDICES A. STUDY 1 - ICELAND PRE- AND POST-TEST 208 B. STUDY 2 - TONGA PRE- AND POST-TEST 211 C. COMSOL QUANTIFICATION 216 VITA 226 vii LIST OF TABLES Table Page 1. Average scores on pre-test by total, gender, and prior coursework for the Iceland activity 54 2. Comparing overall scores for pre- and post-test for the Iceland activity 55 3. Average scores on pre-test and post-test for the Iceland activity by type of prior coursework 56 4. Average scores on pre-test and post-test for the Iceland activity by gender 57 5. Average scores on the Iceland lab activity by gender and prior coursework 57 6. Pearson correlation values between pre-test, post-test, and lab scores for the Iceland activity. *Significant at the p < 0.01 level 58 7. Average scores on pre-test by total, gender, and prior coursework for the Tonga activity 64 8. Overall scores for pre- and post-test for the Tonga activity. *Signifi- cant at the p < .001 level 65 9. Average scores on pre-test and post-test for the Tonga activity by type of prior coursework 66 10. Tonga activity results of average scores on pre-test and post-test by gender 66 11. Average scores on the Tonga lab activity by gender. *Significant at the p < 0.005 level 67 12. Pearson correlation values between pre-test, post-test, and lab scores for the Tonga activity. *Significant at the p < 0.01 level 68 13. Values from earthquake data and calculations. Length is travel dis­ tance from trench 117 14. General boundary conditions used for 2D subduction models in COM- SOL 131 15. Parameter Values for Diffusion Creep and Dislocation Creep in a Dry Upper Mantle from Karato and Wu [1993] 162 viii 16. Parameter Values for Dislocation Creep from Carminati et al. [2005]; Violay et al. [2012] 162 17. Homologous temperatures for linear slope profile at x = 300 km . 179 ix LIST OF FIGURES Figure Page 1.