Hazards and Monitoring of Volcanic Activity, Volume 2: Seismology, Deformation and Remote Sensing

321 Pages·2022·41.248 MB·English

by  Jean-François Lénat

Hazards and Monitoring of Volcanic Activity 2
SCIENCES
Geoscience, Field Director – Yves Lagabrielle
Lithosphere–Asthenosphere Interactions,
Subject Head – René Maury
Hazards and Monitoring of
Volcanic Activity 2
Seismology, Deformation
and Remote Sensing
Coordinated by
Jean-François Lénat
First published 2022 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
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Library of Congress Control Number: 2022934927

British Library Cataloguing-in-Publication Data
A CIP record for this book is available from the British Library
ISBN 978-1-78945-045-3
ERC code:
PE10 Earth System Science
PE10_5 Geology, tectonics, volcanology
PE10_7 Physics of earth’s interior, seismology, volcanology
Contents
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Claude JAUPART
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Jean-François LÉNAT
List of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Chapter 1. Seismic Monitoring of Volcanoes and Eruption
Forecasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Philippe LESAGE
1.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Instrumentation and seismic networks . . . . . . . . . . . . . . . . . . . . 2
1.2.1. Measurement systems . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.2. Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.3. Monitoring network . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Types of seismic-volcanic events . . . . . . . . . . . . . . . . . . . . . . . 10
1.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3.2. Volcano-tectonic earthquakes (VT, A-type,
high-frequency, HF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3.3. Long-period earthquakes (LP, B-type, low-frequency, LF) . . . . 12
1.3.4. Hybrid earthquakes (C-type, multiphase, MP) . . . . . . . . . . . . 14
1.3.5. Explosions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
vi Hazards and Monitoring of Volcanic Activity 2
1.3.6. Very-long-period (VLP or VLF) and ultra-long-period
(ULP) events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.3.7. Volcanic tremor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.3.8. Surficial phenomena . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.3.9. Distortions in seismic signals . . . . . . . . . . . . . . . . . . . . . . 20
1.4. Volcanic seismicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.4.1. Main characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.4.2. Pre-eruptive seismic activity, precursors . . . . . . . . . . . . . . . 24
1.4.3. Generic models of seismic-volcanic swarms and
pre-eruptive seismicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.5. Processing of seismic-volcanic signals . . . . . . . . . . . . . . . . . . . . 30
1.5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.5.2. Seismograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.5.3. Event detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.5.4. RSAM, RSEM, SSAM . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.5.5. Spectral analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.5.6. Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.5.7. Correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.5.8. Determination of the Base Level Noise Seismic Spectrum . . . . 37
1.5.9. Automatic classification . . . . . . . . . . . . . . . . . . . . . . . . . 37
1.6. Network data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
1.6.1. Determination of velocity models . . . . . . . . . . . . . . . . . . . 40
1.6.2. Location of seismic sources . . . . . . . . . . . . . . . . . . . . . . . 40
1.6.3. Seismic moment tensor inversion . . . . . . . . . . . . . . . . . . . 46
1.6.4. Array analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
1.6.5. Coda wave interferometry . . . . . . . . . . . . . . . . . . . . . . . . 49
1.7. Forecasting eruptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
1.7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
1.7.2. Probabilistic forecasting . . . . . . . . . . . . . . . . . . . . . . . . . 56
1.7.3. Short-term forecasting . . . . . . . . . . . . . . . . . . . . . . . . . . 57
1.8. The FFM method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
1.8.1. Alert systems and volcanic crisis management . . . . . . . . . . . 60
1.9. Case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
1.9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
1.9.2. Kelud volcano, Java, Indonesia . . . . . . . . . . . . . . . . . . . . . 63
1.9.3. The “centennial” eruption of Merapi volcano, 2010 . . . . . . . . 67
1.9.4. Piton de la Fournaise . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
1.9.5. Phreatic eruptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
1.9.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
1.10. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
1.11. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Contents vii
Chapter 2. Monitoring Volcano Deformation . . . . . . . . . . . . . . . . 95
Valérie CAYOL, Aline PELTIER, Jean-Luc FROGER and
François BEAUDUCEL
2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
2.2. Phenomena at the origin of deformation . . . . . . . . . . . . . . . . . . . 97
2.2.1. Deformation related to the inflation-deflation of magmatic
reservoirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
2.2.2. Deformation related to magma ascent inside the conduits . . . . . 101
2.2.3. Deformation of hydrothermal origin . . . . . . . . . . . . . . . . . . 104
2.2.4. Flank destabilization related to endogenous growth . . . . . . . . . 106
2.2.5. Other sources of deformation . . . . . . . . . . . . . . . . . . . . . . 107
2.3. Deformation measurement techniques . . . . . . . . . . . . . . . . . . . . 107
2.3.1. Leveling measurements . . . . . . . . . . . . . . . . . . . . . . . . . 108
2.3.2. Tilt measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
2.3.3. Extensometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
2.3.4. Electronic Distance Measurement, trilateration . . . . . . . . . . . 113
2.3.5. Volumetric strainmeters . . . . . . . . . . . . . . . . . . . . . . . . . 114
2.3.6. Satellite positioning system, GNSS . . . . . . . . . . . . . . . . . . 115
2.3.7. InSAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
2.3.8. Stereophotogrammetry . . . . . . . . . . . . . . . . . . . . . . . . . . 125
2.3.9. Measurements at sea . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
2.4. Adequacy between deformation measurements and monitoring . . . . . 126
2.5. Contributions and limitations of deformation modeling to the
study of volcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
2.5.1. Reservoir models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
2.5.2. Conduit models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
2.5.3. Models without a priori assumptions on source shape . . . . . . . 149
2.6. Perspectives: from operational monitoring to physical and
predictive models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
2.7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Chapter 3. Volcano Monitoring by Remote Sensing . . . . . . . . . . . 167
Mathieu GOUHIER
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
3.2. Basic concepts in remote sensing . . . . . . . . . . . . . . . . . . . . . . . 168
3.2.1. Passive and active sensors . . . . . . . . . . . . . . . . . . . . . . . . 169
3.2.2. Geostationary and Low Earth Orbit platforms . . . . . . . . . . . . 170
3.2.3. Electromagnetic spectrum . . . . . . . . . . . . . . . . . . . . . . . . 172
3.2.4. Terrestrial infrared radiation . . . . . . . . . . . . . . . . . . . . . . 175
viii Hazards and Monitoring of Volcanic Activity 2
3.2.5. Spectral resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
3.3. Main available operating systems . . . . . . . . . . . . . . . . . . . . . . . 177
3.4. Monitoring volcanic ash plumes . . . . . . . . . . . . . . . . . . . . . . . 181
3.4.1. Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
3.4.2. List of main available sensors . . . . . . . . . . . . . . . . . . . . . . 186
3.4.3. Case studies: Etna and Eyjafjallajökull . . . . . . . . . . . . . . . . 187
3.5. Monitoring volcanic SO plumes . . . . . . . . . . . . . . . . . . . . . . . 190
2
3.5.1. Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
3.5.2. Operational issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
3.5.3. Case studies: Holuhraun/Bárðarbunga . . . . . . . . . . . . . . . . . 195
3.6. Lava flow monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
3.6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
3.6.2. Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
3.6.3. Case studies: Piton de la Fournaise, 2015 . . . . . . . . . . . . . . . 204
3.7. Future developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
3.8. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Chapter 4. Volcano Remote Sensing with Ground-Based
Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Franck DONNADIEU, David JESSOP, Philipson BANI and
Séverine MOUNE
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
4.2. Basic concepts in ground-based remote sensing relying
on electromagnetic waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
4.2.1. Electromagnetic spectrum . . . . . . . . . . . . . . . . . . . . . . . . 212
4.2.2. Propagation of electromagnetic waves . . . . . . . . . . . . . . . . 213
4.2.3. Scattering and absorption . . . . . . . . . . . . . . . . . . . . . . . . 213
4.3. Ground remote sensing for the detection of volcanic gas . . . . . . . . . 215
4.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
4.3.2. Why become interested in volcanic degassing? . . . . . . . . . . . 216
4.3.3. Measurement methods . . . . . . . . . . . . . . . . . . . . . . . . . . 220
4.3.4. Future developments . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
4.3.5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
4.4. Ground-based IR remote sensing . . . . . . . . . . . . . . . . . . . . . . . 237
4.4.1. History and development of ground-based thermal
remote sensing instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
4.4.2. Examples of thermal cameras used in volcanology . . . . . . . . . 240
4.4.3. Physical principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
4.4.4. Characteristics and practical considerations for using
thermal imaging instruments . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Contents ix
4.5. Other volcano remote sensing methods with ground-based
techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
4.5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
4.5.2. The importance of monitoring ash plumes . . . . . . . . . . . . . . 253
4.5.3. Radars, operational tools . . . . . . . . . . . . . . . . . . . . . . . . . 254
4.5.4. Monitoring proximal ash fallout: disdrometers . . . . . . . . . . . 264
4.5.5. Monitoring of volcanic storms . . . . . . . . . . . . . . . . . . . . . 268
4.5.6. Atmospheric lidars to probe low concentration ash clouds . . . . . 274
4.5.7. Plume detection by GNSS networks . . . . . . . . . . . . . . . . . . 277
4.5.8. Monitoring topographic changes . . . . . . . . . . . . . . . . . . . . 278
4.5.9. Monitoring underwater volcanic activity by means of
acoustic methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
4.6. Future developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
4.7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
List of Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Foreword
Claude JAUPART
Institut de physique du globe de Paris, Université de Paris,
Académie des sciences, France
Volcanoes are fascinating because of the beautiful landscapes they form and
their superb eruptions. Many books have documented the most catastrophic
eruptions, the different eruptive regimes and the physical mechanisms involved.
Others have popularized tales of adventurers getting close to volcanic explosions
and flows at the risk of their lives. In comparison, the discreet and dedicated work of
volcanologists monitoring volcanoes has remained little known. The methods and
techniques they use have improved greatly in recent decades and now allow them to
predict eruptions with very few limitations. These advances are to be presented and
explained in the three volumes of this book.
Volcanoes are built on top of a vast network of underground plumbing, and it is
within this network that eruptions occur. Near the surface, the permeable rocks are
gorged with water that circulates, heats up at depth and vaporizes under widely
varying conditions. The result is a myriad of manifestations, including fumarole
fields with changing flows, small earthquakes and ground deformation. This high
background noise makes monitoring difficult. An eruption is preceded by the setting
in motion of magma from one or more reservoirs located several kilometers
underground. This onset is often very discrete and the associated signals are not
easily distinguished from the background noise. Once the magma is near the surface,
the signs are numerous and leave no room for doubt, but things can move very
quickly and it is often too late to evacuate the area. Simply recognizing that an
eruption is imminent is not enough: one must also assess its intensity and regime.
Sometimes an eruption can even occur without magma and take the form of phreatic
Hazards and Monitoring of Volcanic Activity 2,
coordinated by Jean-François LÉNAT. © ISTE Ltd 2022.