Volcano Deformation New Geodetic Monitoring Techniques

Volcanoes and eruptions are dramatic surface man­ telemetry and processing, and volcano-deformation ifestations of dynamic processes within the Earth, source models over the past three decades. There has mostly but not exclusively localized along the been a virtual explosion of volcano-geodesy studies boundaries of Earth's relentlessly shifting tectonic and in the modeling and interpretation of ground­ plates. Anyone who has witnessed volcanic activity deformation data. Nonetheless, other than selective, has to be impressed by the variety and complexity of brief summaries in journal articles and general visible eruptive phenomena. Equally complex, works on volcano-monitoring and hazards mitiga­ however, if not even more so, are the geophysical, tion (e. g. , UNESCO, 1972; Agnew, 1986; Scarpa geochemical, and hydrothermal processes that occur and Tilling, 1996), a modern, comprehensive treat­ underground - commonly undetectable by the ment of volcano geodesy and its applications was human senses - before, during, and after eruptions. non-existent, until now. Experience at volcanoes worldwide has shown that, In the mid-1990s, when Daniel Dzurisin (DZ to at volcanoes with adequate instrumental monitor­ friends and colleagues) was serving as the Scientist­ ing, nearly all eruptions are preceded and accom­ in-Charge of the USGS Cascades Volcano Observa­ panied by measurable changes in the physical and tory (CVO), I first learned of his dream to write a (or) chemical state of the volcanic system. While book on volcano geodesy.

1 The modern volcanologist’s tool kit.- 1.1 Volcanoes in motion — when deformation gets extreme.- 1.1.1 The ups and downs of a Roman market — Phlegraean Fields Caldera, Italy.- 1.1.2 Remarkable uplifts in the Galápagos Islands — Fernandina and Alcedo Volcanoes.- 1.1.3 Rabaul Caldera, Papua New Guinea, 1994.- 1.1.4 The bulge at Mount St. Helens, 1980.- 1.2 Volcanology in the information age.- 1.2.1 Volcano hazards mitigation — a complicated business.- 1.2.2 Lessons from Armero, Colombia.- 1.2.3 Communication — a key to effective hazards mitigation.- 1.3 A brief survey of volcano-monitoring techniques.- 1.3.1 Seismology ~ cornerstone of volcano monitoring.- 1.3.2 Volcano geochemistry.- 1.3.3 Volcano geophysics.- 1.3.4 Hydrologic responses to stress and strain.- 1.3.5 Remote-sensing techniques.- 1.3.6 Volcano hazards and risk assessment techniques.- 1.3.7 A mobile volcano-monitoring system.- 1.4 An introduction to geodetic sensors and techniques.- 1.4.1 The emergence of volcano geodesy.- 1.4.2 Continuous sensors and repeat surveys.- 1.4.3 Tiltmeters, strainmeters, and continuous GPS.- 1.4.4 Repeated surveys — leveling, FDM, and GPS.- 1.4.5 Photography, photogrammetry, and water-level gauging.- 2 Classical surveying techniques.- 2.1 Early geodetic surveys.- 2.2 Reference systems and datums.- 2.3 Geodetic networks.- 2.4 Trilateration and triangulation.- 2.4.1 FDM and theodolite surveys, with examples from Mount St. Helens and Long Valley Caldera.- 2.4.2 Triangulation and total-station surveys.- 2.5 Leveling and tilt-leveling surveys.- 2.5.1 Field procedures and accuracy.- 2.5.2 Single-setup leveling.- 2.5.3 Geodetic leveling.- 2.5.4 Tilt-leveling results at South Sister Volcano, Oregon.- 2.5.5 Repeated leveling surveys at Medicine Lake Volcano, California.- 2.6 Photogrammetry.- 2.6.1 Mapping the 1980 north flank ‘bulge’ at Mount St. Helens.- 2.6.2 Oblique-angle and fixed-camera photogrammetry.- 2.7 Microgravity surveys.- 2.7.1 Physical principles.- 2.7.2 Results from Kflauea Volcano, Hawai’i.- 2.7.3 Results from Miyakejima Volcano, Japan.- 2.8 Magnetic field measurements.- 2.8.1 Physical mechanisms.- 2.8.2 Changes associated with eruptions at Mount St. Helens.- 2.8.3 Results from Long Valley Caldera.- 3 Continuous monitoring with in situ sensors.- 3.1 Seismometers.- 3.1.1 A brief history of seismology.- 3.1.2 An introduction to seismic waves and earthquake types.- 3.1.3 Basic principles of seismometers.- 3.1.4 Current research topics in volcano seismology.- 3.2 Tiltmeters.- 3.2.1 Short-base bubble tiltmeters.- 3.2.2 The Ideal-Aero smith mercury capacitance tiltmeter.- 3.2.3 Long-base fluid tiltmeters.- 3.3 Strainmeters.- 3.3.1 Linear strainmeters (extensometers).- 3.3.2 The Sacks-Evertson volumetric strainmeter.- 3.3.3 The Gladwin tensor strainmeter.- 3.4 Continuous GPS.- 3.5 Some cautions about near-surface deformation sensors.- 3.6 Continuous gravimeters.- 3.6.1 Absolute gravimeters.- 3.6.2 Relative gravimeters — the magic of zero-length springs and superconductivity.- 3.6.3 Gravity results from selected volcanoes.- 3.7 Differential lake gauging.- 3.7.1 Monitoring active deformation at Lake Taupo, New Zealand.- 3.7.2 Lake terraces as paleo-tiltmeters.- 3.8 Concluding remarks.- 4 The Global Positioning System: A multipurpose tool.- 4.1 Global positioning principles.- 4.1.1 Reference surfaces and coordinate systems: the geoid and ellipsoid.- 4.1.2 Point positioning and relative positioning.- 4.2 An overview of GPS, GLONASS, and Galileo.- 4.2.1 Who controls GPS?.- 4.2.2 NAVSTAR satellite constellation.- 4.2.3 GLONASS satellite constellation.- 4.2.4 Galileo Global Navigation Satellite System.- 4.3 GPS signal structure: what do the satellites broadcast?.- 4.3.1 L1 and L2 carrier signals, C/A-code, P-code, and Y-code.- 4.3.2 Selective availability and anti-spoofing.- 4.3.3 Navigation message.- 4.4 Observables: what do GPS receivers measure?.- 4.4.1 Code pseudoranges.- 4.4.2 Carrier phase and carrier-beat phase.- 4.5 Data combinations and differences.- 4.5.1 Wide-lane and narrow-lane combinations.- 4.5.2 The L3 combination.- 4.5.3 Single differences.- 4.5.4 Double differences.- 4.5.5 Triple differences.- 4.6 Doing the math: turning data into positions.- 4.6.1 Point positioning with code pseudoranges.- 4.6.2 Point positioning with carrier-beat phases.- 4.6.3 Static relative positioning.- 4.6.4 Kinematic relative positioning.- 4.6.5 Ambiguity resolution.- 4.7 Relative positioning techniques.- 4.7.1 Static GPS.- 4.7.2 Stop-and-go kinematic GPS.- 4.7.3 Kinematic GPS.- 4.7.4 Pseudokinematic GPS.- 4.7.5 Rapid static GPS.- 4.7.6 Real time kinematic OTF GPS.- 4.7.7 Which type of GPS receiver and field procedures are right for the job?.- 4.8 CGPS networks.- 4.8.1 GEONET The national GPS network of Japan.- 4.8.2 The US Continuously Operating Reference Station (CORS) network.- 4.8.3 SCIGN The Southern California Integrated GPS Network.- 4.8.4 PANGA — The Pacific Northwest Geodetic Array.- 4.8.5 The discovery of slow earthquakes in the Pacific Northwest.- 4.8.6 Tracking deformation events at K?lauea Volcano, Hawai’i, with CGPS.- 4.8.7 Continuous, real time GPS network at the Long Valley Caldera.- 4.9 Data processing.- 4.9.1 GPS software packages.- 4.9.2 Precise point positioning.- 4.10 Looking to the future.- 4.10.1 Lightweight, low-power GPS receivers.- 4.10.2 Automated GPS data processing.- 4.10.3 EarthScope and the PBO.- 5 Interferometric synthetic-aperture radar (InSAR).- 5.1 Radar principles and techniques.- 5.1.1 Real-aperture imaging radar systems.- 5.1.2 Ground resolution of real-aperture imaging radars.- 5.1.3 Synthetic-aperture radar.- 5.1.4 Characteristics of SAR images.- 5.2 Principles of SAR interferometry.- 5.2.1 Co-registration of overlapping radar images.- 5.2.2 Creating the interferogram.- 5.2.3 Removing the effects of viewing geometry and topography.- 5.2.4 Two-pass, three-pass, and four-pass interferometry 17.- 5.2.5 DEMs derived from InSAR.- 5.2.6 Lidar, InSAR, and photo gramme try — a potent remote-sensing triad.- 5.2.7 Range-change resolution of InSAR.- 5.2.8 Coping with decorrelation and atmospheric-delay anomalies.- 5.2.9 Volcano InSAR studies: a growing list of success stories.- 5.3 Examples of interferometric SAR applied to volcanoes.- 5.3.1 Mount Etna.- 5.3.2 Long Valley Caldera, California.- 5.3.3 Yellowstone Caldera, Wyoming.- 5.3.4 Akutan Volcano, Alaska.- 5.3.5 Westdahl Volcano, Alaska.- 5.3.6 Three Sisters volcanic center, Oregon.- 5.3.7 The future of volcano InSAR.- 6 Photogrammetry.- 6.1 Introduction.- 6.2 Historical perspective.- 6.3 Photogrammetry fundamentals.- 6.3.1 Introduction.- 6.3.2 Aerial cameras.- 6.3.3 Format, focal length, and field of view.- 6.3.4 Photo collection and scale.- 6.3.5 Relief displacemen t.- 6.3.6 Orientation.- 6.3.7 Photogrammetric accuracy.- 6.4 Instrumentation and data types.- 6.4.1 Analog stereoplotters.- 6.4.2 Analytical stereoplotters.- 6.4.3 Softcopy stereoplotters.- 6.4.4 Display systems.- 6.4.5 Computer-assisted orientation.- 6.4.6 Digital elevation models.- 6.4.7 Orthophotos.- 6.4.8 Satellite imagery.- 6.5 Aerotriangulation.- 6.6 Terrestrial photogrammetry.- 6.7 Application to Mount St. Helens.- 7 Lessons from deforming volcanoes.- 7.1 Mount St. Helens — edifice instability and dome growth.- 7.1.1 Precursory activity: the north flank ‘bulge’.- 7.1.2 Monitoring and predicting the growth of a lava dome.- 7.2 K?lauea volcano, Hawai’i — flank instability and gigantic landslides.- 7.2.1 The volcano’s mobile south flank: historical activity.- 7.2.2 Colossal prehistoric landslides and sea waves.- 7.3 Yellowstone — the ups and downs of a restless caldera.- 7.3.1 Tectonic setting and eruptive history.- 7.3.2 Results of repeated leveling surveys.- 7.3.3 What happened between leveling surveys?.- 7.3.4 Causes of uplift and subsidence.- 7.3.5 Spatiotemporal changes in deformation revealed by InSAR.- 7.4 Long Valley Caldera and the Mono-Inyo volcanic chain: two decades of unrest (and still counting?).- 7.4.1 Erupti