Geoscientific Research and the Global Positioning System Recent Developments and Future Prospects A Report of the University Navstar Consortium Summer, 1994 ii Contents 1 Overview . 1 1.1 State of the Art . 2 1.1.1 Complex Deformation in Plate Boundary Zones. 2 1.1.2 Capturing Earthquakes . 2 1.1.3 Continuously Operating GPS Networks . 4 1.1.4 Volcano Monitoring. 4 1.1.5 Post-Glacial Rebound . 5 1.1.6 Global Climate Change . 5 1.1.7 Ocean Circulation . 6 1.1.8 Atmospheric Sensing . 6 1.1.9 Space-Based GPS Meteorology . 7 1.1.10 Probing the Ionosphere . 7 1.2 The Future . 7 1.2.1 Permanently Operating Networks . 7 1.2.2 Multipurpose National Network . 8 1.2.3 Global Change Research . 8 1.2.4 Space-Based Meteorology . 9 2 Contributors to This Report . 9 3 UNAVCO. 9 4 Scientific Opportunities . 11 4.1 Deformation of the Earth’s Lithosphere . 11 4.1.1 Plate Boundary Processes . 12 4.1.1.1 Mantle Dynamics and Tibet . 14 4.1.1.2 The Pacific-North American Transform Boundary . 14 4.1.1.3 Complexity of Continental Convergence in the Eastern Mediterranean . 14 4.1.1.4 Southeast Asia and Indonesia Tectonics . 17 4.1.1.5 The Interior Western U.S. and the Transition to the Stable Plate Interior . 18 4.1.2 Volcanic Processes . 20 4.1.2.1 Kilauea . 22 4.1.2.2 The Yellowstone Caldera . 23 4.2 The Earthquake Cycle . 24 4.2.1 Loma Prieta . 26 4.3 Deep Earth and Whole Earth Applications . 27 4.3.1 Earth Rotation . 27 4.4 Interaction of Mantle Convection and Tectonics. 29 4.4.1 Vertical Motions. 29 4.4.2 Horizontal Motions . 30 4.4.3 Post-Glacial Rebound . 31 4.5 Ice Dynamics and Sea Level . 33 4.5.1 Ice Dynamics . 33 iii 4.5.1.1 Mass Balance . 33 4.5.1.2 Ice Sheet Dynamics . 34 4.5.2 Sea Level: The Link Between Ice Dynamics and Tectonics. 34 4.6 Precise Mapping and Navigation in Oceanography . 35 4.6.1 Mapping of Global Sea Height . 36 4.6.2 Acoustic Doppler Current Profiling . 37 4.6.3 Ocean Warming . 37 4.6.4 Seafloor Mapping. 39 4.6.5 Other Shipboard Applications . 39 4.7 Atmospheric Sensing . 40 4.7.1 Ground-Based GPS Meteorology . 41 4.7.2 Future Opportunities in Ground-Based GPS Meteorology. 42 4.7.3 Space-Based Meteorology with GPS . 44 4.7.4 Probing the Ionosphere . 45 4.8 Instrument Arrays and Data Networks . 45 5 Accomplishments and Ideas . 46 5.1 Subsurface Geodesy. 46 5.2 Measurement of Local Geoid Slope. 47 5.3 Precise Airborne Surface Altimetry Based on GPS Positioning . 47 5.4 Airborne Geophysical Observations of Long Valley Caldera . 48 5.5 GPS Measurement of Relative Motion of the Cocos and Caribbean Plates and Strain Accumulation Across the Middle America Trench . 49 5.6 Constraints on Deformation of the Resurgent Dome, Long Valley Caldera, California from Space Geodesy . 49 5.7 GPS Monitoring of Crustal Strain in Southwest British Columbia with the Western Canada Deformation Array.. 50 5.8 GPS Used to Monitor Ground Movements at Augustine Volcano, Alaska . 50 5.9 Use of Airborne Kinematic GPS and Laser Altimetry for Determining Volume Changes of Mountain Glaciers . 51 5.10 Use of GPS Technology in Glaciology . 52 5.11 Solar Hygrometer for GPS Field Use . 53 5.12 Non-Equilibrium Forces on GPS Satellites . 54 5.13 Sub-Daily Earth Rotation During Epoch’92 from GPS . 54 5.14 Atmospheric Excitation of Rapid Polar Motions Measured by GPS. 55 5.15 Large Scale Combination of GPS and VLBI Data. 55 5.16 Antarctic Search for Meteorites (ANSMET) Project . 56 5.17 Landslide Hazard and GPS . 57 5.18 Crustal Deformation at Convergent Plate Boundaries . 58 5.19 The GPS Flight Experiment on Topex/Poseidon . 59 5.20 Use of GPS for Tethered Satellite Position Determination . 60 5.21 Status of GPS/Acoustic Measurements of Seafloor Strain Accumulation Across the Cascadia Subduction Zone . ..