Volcano Deformation (eBook)

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 Eruptive history and recent unrest.- 7.4.2 Leveling results: tracking caldera inflation in space and time.- 7.4.3 Regional and intracaldera trilateration surveys.- 7.4.4 Repeated and continuous GPS measurements.- 7.4.5 Temporal gravity changes.- 7.4.6 Borehole strainmeter and long-base tiltmeter results: implications of triggered seismicity.- 7.4.7 Water-level changes induced by distant earthquakes: evidence for stimulated upward movement of magma or hydrothermal fluid.- 7.4.8 Long Valley summary.- 8 Analytical volcano deformation source models.- 8.1 Introduction.- 8.2 The elastic half-space: a first approximation of the Earth.- 8.2.1 Properties of an isotropic linearly elastic solid.- 8.2.2 Elastic constants.- 8.3 Notation.- 8.3.1 Coordinate system and displacements.- 8.3.2 Stress and strain.- 8.3.3 Tilt.- 8.4 Surface loads.- 8.4.1 Deformation from point, uniform disk, and uniform rectangular surface loads.- 8.5 Point forces, pipes, and spheroidal pressure sources.- 8.5.1 Spheroidal cavities and pipes: model elements for inflating and deflating magma chambers and vertical conduits.- 8.5.2 Point pressure source.- 8.5.3 Finite spherical pressure source.- 8.5.4 Closed pipe: a model for a plugged conduit or a cigar-shaped magma chamber.- 8.5.5 Closed pipe tilt and strain components.- 8.5.6 Open pipe: a composite model for the filling of an open conduit.- 8.5.7 Sill-like magma chambers.- 8.6 Dipping point and finite rectangular tension cracks.- 8.7 Gravity change.- 8.8 Relationship between subsurface and surface volume changes.- 8.9 Topographic corrections to modeled deformation.- 8.9.1 Reference elevation model.- 8.9.2 Varying depth model.- 8.9.3 Topographically corrected model.- 8.10 Inversion of source parameters from deformation data.- 8.10.1 Non-linear inversion and model parameter error estimates.- 8.10.2 Choosing the best source model.- 9 Borehole observations of continuous strain and fluid pressure.- 9.1 Borehole strainmeter design and capabilities.- 9.2 Groundwater level as a volumetric strain indicator.- 9.2.1 Water levels and crustal strain.- 9.2.2 Effects of groundwater flow.- 9.2.3 Thermal pressurization.- 9.2.4 Data collection requirements.- 9.3 Processing and analyzing continuous strain and water level data.- 9.4 Volumetric strain fields of idealized volcanic sources.- 9.4.1 Center of dilatation.- 9.4.2 Vertical conduit models.- 9.4.3 Dike intrusion.- 9.5 Examples.- 9.5.1 Izu Peninsula, Japan.- 9.5.2 Long Valley Caldera, California: stimulation by distant earthquakes.- 9.5.3 Eruptions of Hekla, Iceland, in 1991 and 2000.- 9.5.4 Eruption of Usu Volcano, Japan, March 2000.- 9.5.5 Spreading of the western Pacific sea floor on the Juan de Fuca Ridge.- 9.6 Summary.- 10 Hydrothermal systems and volcano geochemistry.- 10.1 The hydrologic importance of brittle-plastic phenomena.- 10.2 The brittle-plastic transition.- 10.2.1 General considerations.- 10.2.2 Brittle-plastic transition in an active volcanic environment.- 10.2.3 Brittle behavior of normally plastic rock at high strain rates.- 10.3 Development of plastic rock around shallow intrusive bodies.- 10.4 Storage of hydrothermal fluid in and movement through plastic rock.- 10.4.1 Accumulation in horizontal lenses in plastic rock when and where ?3 = Sv.- 10.4.2 Significance of accumulation of fluid in plastic rock at near lithostatic Pf.- 10.4.3 Rapid upward movement of fluid through plastic rock when ?3 400°C fluid into cooler rock.- 10.7 Chemical characteristics of fluids in a sub-volcanic environment.- 10.7.1 Salinity variations and phase relations of aqueous fluids at >400°C.- 10.7.2 Generation and behavior of HCl at high temperature and low Pf.- 10.7.3 Behavior of H2S and SO2 in sub-volcanic hydrothermal systems.- 10.7.4 Decompression of the ‘steam’ phase.- 10.8 A general model of hydrothermal activity in a sub-volcanic environment.- 10.9 Uplift and subsidence of large silicic calderas.- 10.10 Conclusions.- 11 Challenges and opportunities for the 21st century.- 11.1 The intrusion process: a complicated business.- 11.2 Strengths and weaknesses of geodetic monitoring.- 11.3 Why is volcano deformation such an elusive target?.- 11.3.1 This should be easy!.- 11.3.2 Lessons from Mount St. Helens I: 1980.- 11.3.3 Lessons from Yellowstone.- 11.3.4 Lessons from Mount St. Helens II: 2004–2006 (continuing education).- 11.4 Capturing volcano deformation in space and time.- 11.4.1 Real-time, global surveillance: an achievable goal.- 11.4.2 On-the-fly volcano modeling.- 11.4.3 Implications for eruption forecasting and hazards mitigation.- 11.5 Pie-in-the-sky volcanology.- 11.6 A bright and challenging future.- References.- DVD with figures and supplementary material.