bfm-3A978-1-4020-4423-6-2F1

ENCYCLOPEDIAof GEOMAGNETISM

AND PALEOMAGNETISM

Encyclopedia ofEarth Sciences Series

ENCYCLOPEDIA OF GEOMAGNETISM AND PALEOMAGNETISM

Volume EditorsDavid Gubbins is Research Professor of Earth Sciences in the School of Earth and Environment, University of Leeds, UK. He did his PhD ongeomagnetic dynamos in Cambridge, supervised by Sir Edward Bullard and has worked in the USA, and in Cambridge before moving to Leedsin 1989. His work has included dynamo theory and its connection with the Earth's thermal history, modeling the Earth's magnetic field fromhistorical measurements, and recently the interpretation of paleomagnetic data. He is a fellow of the Royal Society and has been awarded the goldmedal of the Royal Astronomical Society and the John Adam Fleming Medal of the American Geophysical Union for original research andleadership in geomagnetism.

Emilio Herrero-Bervera is Research Professor of Geophysics at the School of Ocean and Earth Science and Technology (SOEST) within theHawaii Institute of Geophysics and Planetology (HIGP) of the University of Hawaii at Manoa, where he is the head of the Paleomagnetics andPetrofabrics Laboratory. During his career he has published over 90 papers in professional journals including Nature, JGR, EPSL, JVGR. He hasworked in such diverse fields as volcanology, sedimentology, plate tectonics, and has done field work on five continents.

Aim of the SeriesThe Encyclopedia of Earth Sciences Series provides comprehensive and authoritative coverage of all the main areas in the earth sciences. Eachvolume comprises a focused and carefully chosen collection of contributions from leading names in the subject, with copious illustrations andreference lists.

These books represent one of the world's leading resources for the Earth sciences community. Previous volumes are being updated and new workspublished so that the volumes will continue to be essential reading for all professional Earth scientists, geologists, geophysicists, climatologists,and oceanographers as well as for teachers and students.

See the back of this volume for a current list of titles in the Encyclopedia of Earth Sciences Series. Go to http://www.springerlink.com/reference-works/ to visit the “Earth Sciences Series” on-line.

About the EditorsProfessor Rhodes W. Fairbridge{ has edited 24 encyclopedias in the Earth Sciences Series. During his career he has worked as a petroleumgeologist in the Middle East, been a World War II intelligence officer in the SW Pacific, and led expeditions to the Sahara, Arctic Canada, ArcticScandinavia, Brazil, and New Guinea. He was Emeritus Professor of Geology at Columbia University and was affiliated with the GoddardInstitute for Space Studies.

Professor Michael Rampino has published more than 100 papers in professional journals including Science, Nature, and Scientific American.He has worked in such diverse fields as volcanology, planetary science, sedimentology, and climate studies, and has done field work on sixcontinents. He is currently Associate Professor of Earth and Environmental Sciences at New York University and a consultant at NASA'sGoddard Institute for Space Studies.

ENCYCLOPEDIA OF EARTH SCIENCES SERIES

ENCYCLOPEDIAof GEOMAGNETISM

AND PALEOMAGNETISM

edited by

DAVID GUBBINSUniversity of Leeds

and

EMILIO HERRERO-BERVERA

University of Hawaii at Manoa

A C.I.P. Catalogue record for this book is available from the Library of Congress.

ISBN-13: 978-1-4020-3992-8

This publication is available also asElectronic publication under ISBN 978-1-4020-4423-6 andPrint and electronic bundle under ISBN 978-1-4020-4866-1

Published by SpringerPO Box 17, 3300 AA Dordrecht, The Netherlands

Printed on acid‐free paper

Cover photo: Part of “A Digital Age Map of the Ocean Floor”, by Mueller, R.D., Roest, W.R., Royer, J.‐Y., Gahagan, L.M., and Sclater, J.G.,SIO Reference Series 93-30, Scripps Institution of Oceanography (map downloaded courtesy of NGDC).

Every effort has been made to contact the copyright holders of the figures and tables which have been reproduced from other sources. Anyonewho has not been properly credited is requested to contact the publishers, so that due acknowledgment may be made in subsequent editions.

All Rights Reserved© 2007 SpringerNo part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical,photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material suppliedspecifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work.

Dedication

Jack A. Jacobs (1916–2003)

This encyclopedia is dedicated to the memory of Jack Jacobs. He madecontributions across the whole spectrum of geomagnetism andpaleomagnetism throughout a long and productive career. His booksMicropulsations, Geonomy, The Earth’s Core and Geomagnetism,Reversals of the Earth’s Magnetic Field, and the four volumes of

Geomagnetism intended to replace Chapman & Bartels’ work ofthe same name, cover the field. For this encyclopedia he completedarticles for both editors, on disc dynamo and geomagnetic excursions,and was working on superchrons and changes in reversal frequency atthe end.

Contents

List of Contributors xv

Preface xxv

Aeromagnetic Surveying 1Mark Pilkington

Agricola, Georgius (1494–1555) 3Allan Chapman

Alfvén Waves 3Christopher Finlay

Alfvén, Hannes Olof Gösta (1908–1995) 6Carl-Gunne Fälthammar and David Gubbins

Alfvén's Theorem and the Frozen Flux Approximation 7Paul H. Roberts

Anelastic and Boussinesq Approximations 11Stanislav I. Braginsky and Paul H. Roberts

Anisotropy, Electrical 20Karsten Bahr

Antidynamo and Bounding Theorems 21Friedrich Busse and Michael Proctor

Archeology, Magnetic Methods 23Armin Schmidt

Archeomagnetism 31Donald D. Tarling

Auroral Oval 33Stephen Milan

Baked Contact Test 35Kenneth L. Buchan

Bangui Anomaly 39Patrick T. Taylor

Barlow, Peter (1776–1862) 40Emmanuel Dormy

Bartels, Julius (1899–1964) 42Karl-Heinz Glaßmeier and Manfred Siebert

Bauer, Louis Agricola (1865–1932) 42Gregory A. Good

Bemmelen, Willem van (1868–1941) 44Art R.T. Jonkers

Benton, E. R. 44David Loper

Bingham Statistics 45Jeffrey J. Love

Biomagnetism 48Michael D. Fuller and Jon Dobson

Blackett, Patrick Maynard Stuart, Baronof Chelsea (1887–1974) 53

Michael D. Fuller

Bullard, Edward Crisp (1907–1980) 54David Gubbins

Carnegie Institution of Washington, Department of TerrestrialMagnetism 56

Gregory A. Good

Carnegie, Research Vessel 58Gregory A. Good

Champ 59Stefan Maus

Chapman, Sydney (1888–1970) 61Stuart R.C. Malin

Coast Effect of Induced Currents 61Ted Lilley

Compass 66Art R.T. Jonkers

Conductivity Geothermometer 69Ted Lilley

Conductivity, Ocean Floor Measurements 71Steven Constable

Convection, Chemical 73David Loper

Convection, Nonmagnetic Rotating 74Andrew Soward

Core Composition 77William F. McDonough

viii CONTENTS

Core Convection 80Keke Zhang

Core Density 82Guy Masters

Core Motions 84Kathryn A. Whaler

Core Origin 89Francis Nimmo

Core Properties, Physical 91Frank D. Stacey

Core Properties, Theoretical Determination 94David Price

Core Temperature 98David Price

Core Turbulence 101Bruce Buffett and Hiroaki Matsui

Core Viscosity 104Lidunka Vočadlo

Core, Adiabatic Gradient 106Orson L. Anderson

Core, Boundary Layers 111Emmanuel Dormy, Paul H. Roberts, and Andrew Soward

Core, Electrical Conductivity 116Frank D. Stacey

Core, Magnetic Instabilities 117David R. Fearn

Core, Thermal Conduction 120Frank D. Stacey

Core-Based Inversions for the Main Geomagnetic Field 122David Gubbins

Core-Mantle Boundary Topography, Implications for Dynamics 124Andrew Soward

Core-Mantle Boundary Topography, Seismology 125Andrea Morelli

Core-Mantle Boundary, Heat Flow Across 127Stéphane Labrosse

Core-Mantle Coupling, Electromagnetic 130Richard Holme

Core-Mantle Coupling, Thermal 132Jeremy Bloxham

Core-Mantle Coupling, Topographic 135Dominique Jault

Cowling, Thomas George (1906–1990) 137Leon Mestel

Cowling's Theorem 138Friedrich Busse

Cox, Allan V. (1926–1987) 139Kenneth P. Kodama

Crustal Magnetic Field 140Dhananjay Ravat

D00 and F-Layers 145David Gubbins

D00 as a Boundary Layer 145David Loper

D00, Anisotropy 146Michael Kendall

D00, Composition 149Quentin Williams

D00, Seismic Properties 151Thorne Lay

Della Porta, Giambattista (1535–1615) 156Allan Chapman

Demagnetization 156Jaime Urrutia-Fucugauchi

Depth to Curie Temperature 157Mita Rajaram

Dipole Moment Variation 159Catherine Constable

Dynamo Waves 161Graeme R. Sarson

Dynamo, Backus 163Ashley P. Willis

Dynamo, Braginsky 164Graeme R. Sarson

Dynamo, Bullard-Gellman 166Graeme R. Sarson

Dynamo, Disk 167Jack A. Jacobs

Dynamo, Gailitis 169Agris Gailitis

Dynamo, Herzenberg 170Paul H. Roberts

Dynamo, Lowes-Wilkinson 173Frank Lowes

Dynamo, Model-Z 174Rainer Hollerbach

Dynamo, Ponomarenko 175Paul H. Roberts

Dynamo, Solar 178Eugene N. Parker

Dynamos, Experimental 183Andreas Tilgner

Dynamos, Fast 186Michael Proctor

Dynamos, Kinematic 188Philip W. Livermore

Dynamos, Mean-Field 192Karl-Heinz Raedler

Dynamos, Periodic 200David Gubbins

Dynamos, Planetary and Satellite 203David J. Stevenson

Earth Structure, Major Divisions 208Brian Kennett

CONTENTS ix

Elsasser, Walter M. (1904–1991) 214Eugene N. Parker

EM Modeling, Forward 215Dmitry B. Avdeev

EM Modeling, Inverse 219Gary D. Egbert

EM, Industrial Uses 223Graham Heinson

EM, Lake-Bottom Measurements 227Adam Schultz

EM, Land Uses 228Louise Pellerin

EM, Marine Controlled Source 231Nigel Edwards

EM, Regional Studies 242Oliver Ritter

EM, Tectonic Interpretations 245Malcolm Ingham

Environmental Magnetism 248Barbara A. Maher

Environmental Magnetism, Paleomagnetic Applications 256Andrew P. Roberts

Equilibration of Magnetic Field, Weak- and Strong-FieldDynamos 262

Keke Zhang

Euler Deconvolution 263Alan B. Reid

First-Order Reversal Curve (FORC) Diagrams 266Adrian R. Muxworthy and Andrew P. Roberts

Fisher Statistics 272Jeffrey J. Love

Fleming, John Adam (1877–1956) 273Shaun J. Hardy

Fluid Dynamics Experiments 274Jonathan M. Aurnou

Galvanic Distortion 277Karsten Bahr

Gauss’ Determination of Absolute Intensity 278Stuart R.C. Malin

Gauss, Carl Friedrich (1777–1855) 279Karl-Heinz Glaßmeier

Gellibrand, Henry (1597–1636) 280Stuart R.C. Malin

Geocentric Axial Dipole Hypothesis 281Michael W. McElhinny

Geodynamo 287Chris Jones

Geodynamo, Dimensional Analysis and Timescales 297David Gubbins

Geodynamo, Energy Sources 300Stéphane Labrosse

Geodynamo: Numerical Simulations 302Gary A. Glatzmaier

Geodynamo, Symmetry Properties 306David Gubbins

Geomagnetic Deep Sounding 307Roger Banks

Geomagnetic Dipole Field 310Frank Lowes

Geomagnetic Excursion 311Jack A. Jacobs

Geomagnetic Field, Asymmetries 313Phillip L. McFadden and Ronald T. Merrill

Geomagnetic Hazards 316Alan W.P. Thomson

Geomagnetic Jerks 319Susan Macmillan

Geomagnetic Polarity Reversals 320Alain Mazaud

Geomagnetic Polarity Reversals, Observations 324Bradford M. Clement

Geomagnetic Polarity Timescales 328William Lowrie

Geomagnetic Pulsations 333Karl-Heinz Glaßmeier

Geomagnetic Reversal Sequence, Statistical Structure 335Phillip L. McFadden

Geomagnetic Reversals, Archives 339Jean-Pierre Valet and Emilio Herrero-Bervera

Geomagnetic Secular Variation 346Ingo Wardinski

Geomagnetic Spectrum, Spatial 350Frank Lowes

Geomagnetic Spectrum, Temporal 353Catherine Constable

Geomagnetism, History of 355Art R.T. Jonkers

Gilbert, William (1544–1603) 360Allan Chapman

Gravitational Torque 362Jean-Louis Le Mouel

Gravity-Inertio Waves and Inertial Oscillations 364Keith Aldridge

Grüneisen's Parameter for Iron and Earth's Core 366Orson L. Anderson

Halley, Edmond (1656–1742) 375Sir Alan Cook

Hansteen, Christopher (1784–1873) 376Johannes M. Hansteen

Harmonics, Spherical 377Denis Winch

Harmonics, Spherical Cap 395G.V. Haines

Hartmann, Georg (1489–1564) 397Allan Chapman

x CONTENTS

Helioseismology 398Michael J. Thompson

Higgins-Kennedy Paradox 401Friedrich Busse

Humboldt, Alexander Von (1759–1859) 402Friedrich Busse

Humboldt, Alexander Von and Magnetic Storms 404G.S. Lakhina, B.T. Tsurutani, W.D. Gonzalez, and S. Alex

IAGA, International Association of Geomagnetismand Aeronomy 407

David Kerridge

Ideal Solution Theory 408Dario Alfè

IGRF, International Geomagnetic Reference Field 411Susan Macmillan

Induction Arrows 412Oliver Ritter

Induction from Satellite Data 413Steven Constable

Inhomogeneous Boundary Conditions and the Dynamo 416Keke Zhang

Inner Core Anisotropy 418Xiaodong Song

Inner Core Composition 420Lidunka Vočadlo

Inner Core Oscillation 422Keith Aldridge

Inner Core Rotation 423Paul G. Richards and Anyi Li

Inner Core Rotational Dynamics 425Michael G. Rochester

Inner Core Seismic Velocities 427Annie Souriau

Inner Core Tangent Cylinder 430Rainer Hollerbach and David Gubbins

Inner Core, PKJKP 433Hanneke Paulssen

Instrumentation, History of 434Gregory A. Good

Interiors of Planets and Satellites 439Gerald Schubert

Internal External Field Separation 448Denis Winch

Ionosphere 452Arthur D. Richmond

Iron Sulfides 454Leonardo Sagnotti

Jesuits, Role in Geomagnetism 460Agustín Udías

Kircher, Athanasius (1602–1680) 463Oriol Cardus

Langel, Robert A. (1937–2000) 465Michael E. Purucker

Laplace's Equation, Uniqueness of Solutions 466David Gubbins

Larmor, Joseph (1857–1942) 468David Gubbins

Lehmann, Inge (1888–1993) 468David Gubbins

Length of Day Variations, Decadal 469Richard Holme

Length of Day Variations, Long-Term 471L.V. Morrison and F.R. Stephenson

Lloyd, Humphrey (1808–1881) 472Deanis Weaire and J.M.D. Coey

Magnetic Anisotropy, Sedimentary Rocks and Strain Alteration 475Peter D. Weiler

Magnetic Anomalies for Geology and Resources 477Colin Reeves and Juha V. Korhonen

Magnetic Anomalies, Long Wavelength 481Michael E. Purucker

Magnetic Anomalies, Marine 483James R. Heirtzler

Magnetic Anomalies, Modeling 485Jafar Arkani-Hamed

Magnetic Domains 490Susan L. Halgedahl

Magnetic Field of Mars 502Jafar Arkani-Hamed

Magnetic Field of Sun 505Steven M. Tobias

Magnetic Indices 509Jeffrey J. Love and K.J. Remick

Magnetic Mineralogy, Changes due to Heating 512Bernard Henry

Magnetic Properties, Low-Temperature 515Andrei Kosterov

Magnetic Proxy Parameters 525Mark J. Dekkers

Magnetic Remanence, Anisotropy 535Ann M. Hirt

Magnetic Shielding 540Gary R. Scott

Magnetic Surveys, Marine 542Maurice A. Tivey

Magnetic Susceptibility, Anisotropy 546František Hrouda

Magnetic Susceptibility, Anisotropy, Effects of Heating 560Jaime Urrutia-Fucugauchi

Magnetic Susceptibility, Anisotropy, Rock Fabric 564Edgardo Cañón-Tapia

Magnetic Susceptibility (MS), Low-Field 566Brooks B. Ellwood

Magnetization, Anhysteretic Remanent 572Bruce M. Moskowitz

CONTENTS xi

Magnetization, Chemical Remanent (CRM) 580Shaul Levi

Magnetization, Depositional Remanent 588Jaime Urrutia-Fucugauchi

Magnetization, Isothermal Remanent 589Mike Jackson

Magnetization, Natural Remanent (NRM) 594Mimi J. Hill

Magnetization, Oceanic Crust 596Julie Carlut and Hélène Horen

Magnetization, Piezoremanence and Stress Demagnetization 599Stuart Alan Gilder

Magnetization, Remanent, Ambient Temperature and BurialDepth from Dyke Contact Zones 603

Kenneth L. Buchan

Magnetization, Remanent, Fold Test 607Jaime Urrutia-Fucugauchi

Magnetization, Thermoremanent 609Özden Özdemir

Magnetization, Thermoremanent, in Minerals 616Gunther Kletetschka

Magnetization, Viscous Remanent (VRM) 621David J. Dunlop

Magnetoconvection 630Keke Zhang and Xinhao Liao

Magnetohydrodynamic Waves 632Christopher Finlay

Magnetohydrodynamics 639Paul H. Roberts

Magnetometers, Laboratory 654Wyn Williams

Magnetosphere of the Earth 656Stanley W.H. Cowley

Magnetostratigraphy 664William Lowrie

Magnetotellurics 670Martyn Unsworth

Magsat 673Michael E. Purucker

Main Field Maps 674Mioara Mandea

Main Field Modeling 679Mioara Mandea

Main Field, Ellipticity Correction 683Stuart R.C. Malin

Mantle, Electrical Conductivity, Mineralogy 684Tomoo Katsura

Mantle, Thermal Conductivity 688Frank D. Stacey

Matuyama, Motonori (1884–1958) 689Masaru Kono

Melting Temperature of Iron in the Core, Experimental 689Guoyin Shen

Melting Temperature of Iron in the Core, Theory 692David Price

Microwave Paleomagnetic Technique 694John Shaw

Nagata, Takesi (1913–1991) 696Masaru Kono

Natural Sources for Electromagnetic Induction Studies 696Nils Olsen

Néel, Louis (1904–2000) 700Pierre Rochette

Nondipole Field 701Catherine Constable

Nondynamo Theories 704David J. Stevenson

Norman, Robert (flourished 1560–1585) 707Allan Chapman

Observatories, Overview 708Susan Macmillan

Observatories, Instrumentation 711Jean L. Rasson

Observatories, Automation 713Lawrence R. Newitt

Observatories, Intermagnet 715Jean L. Rasson

Observatories, Program in Australia 717Peter A. Hopgood

Observatories, Program in the British Isles 720David Kerridge

Observatory Program in France 721Mioara Mandea

Observatories, Program in USA 722Jeffrey J. Love and J.B. Townshend

Observatories in Antarctica 723Jean-Jacques Schott and Jean L. Rasson

Observatories in Benelux Countries 725Jean L. Rasson

Observatories in Canada 726Lawrence R. Newitt and Richard Coles

Observatories in China 727Dongmei Yang

Observatories in East and Central Europe 728Pavel Hejda

Observatories in Germany 729Hans-Joachim Linthe

Observatories in India 731Gurbax S. Lakhina and S. Alex

Observatories in Italy 733Massimo Chiappini

Observatories in Japan and Asia 733Toshihiko Iyemori and Heather McCreadie

Observatories in Latin America 734Luiz Muniz Barreto

xii CONTENTS

Observatories in New Zealand and the South Pacific 735Lester A. Tomlinson

Observatories in Nordic Countries 736Truls Lynne Hansen

Observatories in Russia 737Oleg Troshichev

Observatories in Southern Africa 739Pieter Kotzé

Observatories in Spain 739Miquel Torta and Josep Batlló

Ocean, Electromagnetic Effects 740Stefan Maus

Oldham, Richard Dixon (1858–1936) 742Johannes Schweitzer

Ørsted 743Nils Olsen

Oscillations, Torsional 746Mathieu Dumberry

Paleointensity: Absolute Determinations Using SinglePlagioclase Crystals 749

John A. Tarduno, Rory D. Cottrell, and Alexei V. Smirnov

Paleointensity, Absolute, Techniques 753Jean-Pierre Valet

Paleointensity, Relative, in Sediments 758Stefanie Brachfeld

Paleomagnetic Field Collection Methods 765Edgardo Cañón-Tapia

Paleomagnetic Secular Variation 766Steve P. Lund

Paleomagnetism 776Ronald T. Merrill and Phillip L. McFadden

Paleomagnetism, Deep-Sea Sediments 781James E.T. Channell

Paleomagnetism, Extraterrestrial 788Michael D. Fuller

Paleomagnetism, Orogenic Belts 801John D.A. Piper

Parkinson, Wilfred Dudley 807Ted Lilley

Peregrinus, Petrus (flourished 1269) 808Allan Chapman

Periodic External Fields 809Denis Winch

Plate Tectonics, China 816Xixi Zhao and Robert S. Coe

Pogo (OGO-2, -4 and -6 Spacecraft) 828Joseph C. Cain

Polarity Transition, Paleomagnetic Record 829Kenneth A. Hoffman

Polarity Transitions: Radioisotopic Dating 834Brad S. Singer

Pole, Key Paleomagnetic 839Kenneth L. Buchan

Potential Vorticity and Potential Magnetic Field Theorems 840Raymond Hide

Precession and Core Dynamics 842Philippe Cardin

Price, Albert Thomas (1903–1978) 844Bruce A. Hobbs

Principal Component Analysis in Paleomagnetism 845Jeffrey J. Love

Project Magnet 850David G. McMillan

Proudman-Taylor Theorem 852Raymond Hide

Radioactive Isotopes, Their Decay in Mantle and Core 854V. Rama Murthy

Reduction to Pole 856Dhananjay Ravat

Repeat Stations 858Susan Macmillan

Reversals, Theory 859Graeme R. Sarson

Rikitake, Tsuneji (1921–2004) 862Y. Honkura

Ring Current 863Thomas E. Moore

Robust Electromagnetic Transfer Functions Estimates 866Gary D. Egbert

Rock Magnetism 870Ronald T. Merrill

Rock Magnetism, Hysteresis Measurements 874David Krása and Karl Fabian

Rock Magnetometer, Superconducting 883William S. Goree

Runcorn, S. Keith (1922–1995) 886Neil Opdyke

Runcorn's Theorem 888Andrew Jackson

Sabine, Edward (1788–1883) 890David Gubbins

Seamount Magnetism 891James R. Heirtzler and K.A. Nazarova

Secular Variation Model 892Christopher G.A. Harrison

Sedi 902David Loper

Seismic Phases 903Brian Kennett

Seismo-Electromagnetic Effects 908Malcolm J.S. Johnston

Shaw and Microwave Methods, Absolute PaleointensityDetermination 910

John Shaw

Shock Wave Experiments 912Thomas J. Ahrens

CONTENTS xiii

Spinner Magnetometer 920Jiří Pokorný

Statistical Methods for Paleovector Analysis 922Jeffrey J. Love

Storms and Substorms, Magnetic 926Mark Lester

Superchrons, Changes in Reversal Frequency 928Jack A. Jacobs

Susceptibility 931Eduard Petrovsky

Susceptibility, Measurements of Solids 933Z.S. Teweldemedhin, R.L. Fuller, and M. Greenblatt

Susceptibility, Parameters, Anisotropy 937Edgardo Cañón-Tapia

Taylor's Condition 940Rainer Hollerbach

Thellier, Émile (1904–1987) 942David J. Dunlop

Thermal Wind 945Peter Olson

Time-Averaged Paleomagnetic Field 947David Gubbins

Time-Dependent Models of the Geomagnetic Field 948Andrew Jackson

Transfer Functions 953Martyn Unsworth

Transient Em Induction 954Maxwell A. Meju and Mark E. Everett

True Polar Wander 956Vincent Courtillot

ULVZ, Ultra-Low Velocity Zone 970Ed J. Garnero and M. Thorne

Units 973David Gubbins

Upward and Downward Continuation 974Dhananjay Ravat

Variable Field Translation Balance 977David Krása, Klaus Petersen, and Nikolai Petersen

Verhoogen, John (1912–1993) 979Peter Olson

Vine-Matthews-Morley Hypothesis 980Maurice A. Tivey

Volcano-Electromagnetic Effects 984Malcolm J.S. Johnston

Voyages Making Geomagnetic Measurements 987David R. Barraclough

Watkins, Norman David (1934–1977) 992Brooks B. Ellwood

Westward Drift 993Richard Holme

Color Plates 997

Subject Index 1013

Contributors

Thomas J. AhrensCALTECHMS 252-21Pasadena, CA 91125, USAemail: [email protected]

Keith AldridgeDepartment of Earth & Atmospheric SciencesYork University4700 Keele StreetToronto, ON M3J 1P3, Canadaemail: [email protected]

Sobhana AlexIndian Institute of GeomagnetismNew Panvel (W)Navi Mumbai-410 218, Indiaemail: [email protected]

Dario AlfèDepartment of Earth SciencesUniversity College LondonGower StreetLondon, WC1E 6BT, UKemail: [email protected]

Orson L. AndersonInstitute of Geophysics and Planetary PhysicsF83 Department of Earth and Space SciencesUniversity of California, Los Angeles, CA 90095, USAemail: [email protected]

Jafar Arkani-HamedEarth & Planetary SciencesMcGill University3450 University StMontreal, QC H3A 2A7, Canadaemail: [email protected]

Jonathan M. AurnouDepartment of Earth and Space SciencesUniversity of California, Los Angeles595 Charles Young Drive EastLos Angeles, CA 90095-1567, USAemail: [email protected]/[email protected]

Dmitry B. AvdeevSchool of Cosmic PhysicsDublin Institute for Advanced Studies5 Merrion SquareDublin 2, Irelandemail: [email protected]

Karsten BahrGeophysical InstituteUniversität GöttingenHerzberger Landstr. 18037075 Göttingen, Germanyemail: [email protected]

Roger BanksFernwood, RogergroundHawkshead, AmblesideCumbria, LA22 0QG, UKemail: [email protected]

David Barraclough49 Liberton DriveEdinburgh, EH16 6NL, UKemail: [email protected]

Luiz Muniz BarretoObservatorio NacionalRua general Jose Cristino, 77Rio de Janeiro, Brazilemail: [email protected]

Josep BatllóDepartment Matematica Aplicada 1Universitat Polytecnica de CatalunyaSpainemail: [email protected]

Jeremy BloxhamDepartment of Earth and Planetary SciencesHarvard University20 Oxford StreetCambridge, MA 02138, USAemail: [email protected]/[email protected]

Stefanie BrachfeldDepartment of Earth and Environmental StudiesMontclair State UniversityMontclair, NJ 07043, USAemail: [email protected]

Stanislav I. BraginskyInstitute of Geophysics and Planetary PhysicsUCLA405 Hilgard AvenueLos Angeles, CA 90024-1567, USAemail: [email protected]

Kenneth L. BuchanGeological Survey of CanadaNatural Resources Canada601 Booth StreetOttawa, Ontario, K1A 0E8, Canadaemail: [email protected]

xvi CONTRIBUTORS

Bruce BuffettDepartment of Geophysical SciencesUniversity of Chicago5734 S. Ellis AvenueChicago, IL 60637, USAemail: [email protected]

Friedrich BusseInstitute of PhysicsUniversity of Bayreuth95440 Bayreuth, Germanyemail: [email protected]

Joseph C. CainDepartment of GeologyFlorida State UniversityTallahassee, FL 32306-3026, USAemail: [email protected]

Edgardo Cañón-TapiaDepartment of GeologyCICESEP.O. Box 434843San Diego, CA 92143, USAemail: [email protected]

Philippe CardinUniversite Joseph Fourier de GrenobleLaboratoire de Geophysique interne et Tectonophysique1381 Rue de la Piscine, BP 53Grenoble Cedex 9, 38041, Franceemail: [email protected]

Oriol CardusObservatori de l'EbreRoquetesTarragona, 43520, Spainemail: [email protected]

Julie CarlutLaboratoire de GeologieEcole Normale Superieure24 rue LhomondParis, 75235, Franceemail: [email protected]

James E.T. ChannellUniversity of FloridaDepartment of Geological SciencesP.O. Box 112120Gainesville, FL 32611-2120, USAemail: [email protected]

Allan ChapmanModern History Faculty OfficeUniversity of OxfordBroad St.Oxford, OX1 3BD, UKemail: [email protected]

Massimo ChiappiniInstituto Nazionale di Geofisica e VulcanologiaVigna Murata 605Rome, 00143, Italyemail: [email protected]

Bradford M. ClementFlorida International UniversityDepartment of Earth ScienceSW 8th St & 107th AveMiami, FL 33199, USAemail: [email protected]

Robert S. CoeInstitute of Geophysics and Planetary PhysicsUniversity of California Santa Cruz1156 High StreetSanta Cruz, CA 95064, USAemail: [email protected]

J. Michael D. CoeyPhysics Dept.Trinity CollegeCollege GreenDublin 2, Irelandemail: [email protected]

Richard ColesGeomagnetism LaboratoryNatural Resources Canada7 Observatory CrescentOttawa, Ontario K1A0Y3, Canada

Catherine ConstableInstitute of Geophysics and Planetary PhysicsScripps Institution of OceanographyUniversity of California at San DiegoLa Jolla, CA 92093 0225, USAemail: [email protected]

Steven ConstableScripps Institution of OceanographyLa Jolla, CA 920930225, USAemail: [email protected]

Sir Alan Cook (deceased)

Rory D. CottrellDepartment of Earth and Environmental SciencesUniversity of RochesterHutchison Hall 227Rochester, NY 14627, USAemail: [email protected]

Vincent CourtillotInstitut de Physique du Globe de Paris4 place JussieuParis Cedex 05, 75252, Franceemail: [email protected]

Stanley W.H. CowleyDepartment of Physics & AstronomyUniversity of LeicesterLeicester, LE1 7RH, UKemail: [email protected]

Mark J. DekkersDepartment of Earth SciencesUtrecht UniversityBudapestlaan 17Utrecht, 3584 CD, The Netherlandsemail: [email protected]

Jon DobsonCentre for Science & Technology in MedicineKeele UniversityThornburrow DriveHartshill, Stoke-on-Trent ST4 7QB, UK

Emmanuel DormyC.N.R.S./I.P.G.P./E.N.S.Département de PhysiqueEcole Normale Supérieure24, rue Lhomond75231 Paris Cedex 05, Franceemail: [email protected]

Mathieu DumberrySchool of Earth and EnvironmentUniversity of LeedsLeeds, LS2 9JT, UKemail: [email protected]

David J. DunlopDepartment of PhysicsUniversity of TorontoMississauga, Ontario L5L 1C6, Canadaemail: [email protected]

CONTRIBUTORS xvii

Nigel EdwardsDepartment of PhysicsUniversity of Toronto60 St George StreetToronto, Ontario M5S 1A7, Canadaemail: [email protected]

Gary D. EgbertCollege OceanographyOregon State UniversityOceanography Admin Bldg 104Corvallis, OR 97331-5503, USAemail: [email protected]

Brooks B. EllwoodDepartment of Geology and GeophysicsLouisiana State UniversityBaton Rouge, LA 70803, USAemail: [email protected]

Mark E. EverettDepartment of Geology & GeophysicsTexas A & M UniversityCollege Station, TX 77843-3114, USAemail: [email protected]/[email protected]

Karl FabianDepartment of Earth and Environmental SciencesUniversity of MunichTheresienstr. 4180333 München, Germanyemail: [email protected]

Carl-Gunne FälthammarDept. of Plasma PhysicsRoyal Institute of TechnologyStockholm, SE-10044, Swedenemail: [email protected]

David R. FearnDepartment of MathematicsUniversity of GlasgowGlasgow G12 8QW, UKemail: [email protected]

Christopher FinlayETH-HönggerbergInstitute of GeophysicsSchaftmattstrasse 30CH-8093 Zürich, Switzerlandemail: [email protected]

Michael D. FullerPaleomagnetics and Petrofabrics Laboratory1680 East West RdHonolulu, Hawaii, 96822, USAemail: [email protected]

Robert L. Fuller909 River Rd.Colgate Palmolive co.Piscataway, NJ 08854, USA

Agris GailitisInstitute of PhysicsUniversity of LatviaMiera iela 32Salaspils, LV 2169, Latviaemail: [email protected]

Edward J. GarneroDept Geological SciencesArizona State UniversityBox 871404Tempe, AZ 85287-1404, USAemail: [email protected]

Stuart Alan GilderGeophysics SectionLudwig Maximillians UniversityTheresienstrasse 4180333 München, Germanyemail: [email protected]

Karl-Heinz GlaßmeierInstitute of Geophysics and Extraterrestrial PhysicsTechnical University of BraunschweigMendelssohnstr. 338106 Braunschweig, Germanyemail: [email protected]

Gary A. GlatzmaierDepartment of Earth SciencesUniversity of CaliforniaSanta Cruz, CA 95064, USAemail: [email protected]

Walter Demétrio GonzalezINPE-Caixa Postal 5152200 Sao Jose Dos CamposSao Paulo, Brazil

Gregory A. GoodHistory DepartmentWest Virginia UniversityMorgantown, WV 26506-6303, USAemail: [email protected]

William S. GoreeInc. and 2 G Enterprises2040 Sunset DrivePacific Grove, CA 93950, USAemail: [email protected]@2gsuper.com

Martha GreenblattDepartment of Chemistry and Chemical BiologyRutgers University610 Taylor RoadPiscataway, NJ 08854-8087, USAemail: [email protected]

David GubbinsSchool of Earth and EnvironmentUniversity of LeedsLeeds LS2 9JT, UKemail: [email protected]

G.V. Haines69 Amberwood CrOttawa, ON K2E 7C2, Canadaemail: [email protected]@ncf.ca

Susan L. HalgedahlDepartment of Geology and GeophysicsUniversity of UtahSalt Lake City, Utah 84112, USAemail: [email protected]

Truls Lynne HansenTromso Geophysical LaboratoryUniversity of TromsoTromso, N-9037, Norwayemail: [email protected]

Johannes M. Hansteen (deceased)

Shaun J. HardyCarnegie Institution of Washington5241 Broad Branch Rd., N.W.Washington, DC 20015, USAemail: [email protected]

Christopher G.A. HarrisonRosenstiel School of Marine and Atmospheric ScienceUniversity of Miami4600 Rickenbacker CausewayMiami, FL 33149, USAemail: [email protected]

xviii CONTRIBUTORS

Graham HeinsonDepartment of Geology and GeophysicsAdelaide UniversityAdelaide, SA 5005, Australiaemail: [email protected]@adelaide.edu.au

James R. HeirtzlerNASA, Goddard Space Flight CenterMC 920Greenbelt, MD 20771-0001, USAemail: [email protected]

Pavel HejdaGeophysical InstituteAcademy of Sciences of the Czech RepublicBocni II/1401Prague 4, 141 31, Czech Republicemail: [email protected]

Bernard HenryGéomagnétisme et PaléomagnétismeIPGP and CNRS4 avenue de NeptuneSaint-Maur Cedex, 94107, Franceemail: [email protected]

Emilio Herrero-BerveraPaleomagnetics and Petrofabrics LaboratoryUniversity of Hawaii at ManoaHonolulu, Hawaii 96822, USAemail: [email protected]

Raymond Hide17 Clinton AveEast Molesey, Surrey, KT8 0HS, UKemail: [email protected]

Mimi J. HillDepartment of Earth and Ocean SciencesUniversity of LiverpoolOxford StreetLiverpool, L69 7ZE, UKemail: [email protected]@liverpool.ac.uk

Ann M. HirtETH-HönggerbergInstitute of GeophysicsZürich, 8093, Switzerlandemail: [email protected]

Bruce A. HobbsDepartment of Geology and GeophysicsUniversity of EdinburghWest Main RoadEdinburgh, EH9 3JW, UKemail: [email protected]

Kenneth A. HoffmanPhysics DepartmentCalifornia Polytechnic State UniversitySan Luis Obispo, CA 93407, USAemail: [email protected]

Rainer HollerbachSchool of MathematicsUniversity of LeedsLeeds, LS2 9JT, UKemail: [email protected]

Richard HolmeDepartment of Earth and Ocean SciencesUniversity of Liverpool4 Brownlow StreetLiverpool, L69 3GP, UKemail: [email protected]

Yoshimori HonkuraTokyo Institute of TechnologyDepartment of Earth & Planetary Sciences2-12-1-I2-6 OokayamaMeguro-ku, Tokyo, 152-8551, Japanemail: [email protected]

Peter A. HopgoodGeoscience AustraliaGPO Box 378Canberra, ACT, 2601, Australiaemail: [email protected]

Hélène HorenLaboratoire de GeologieEcole Normale Superieure24 rue Lhomond, Paris75235, Franceemail: [email protected]

František HroudaAGICO, Inc.Advanced Geoscience Instruments CompanyJecna 29aBrno, CZ 621 00, Czech Republicemail: [email protected]

Malcolm InghamDepartment of PhysicsUniversity of VictoriaPO Box 600Wellington, New Zealandemail: [email protected]

Toshihiko IyemoriGraduate School ScienceKyoto UniversityData Analysis CenterKyoto, 606-8502, Japanemail: [email protected]

Andrew JacksonSchool of Earth and EnvironmentUniversity of LeedsLeeds LS2 9JT, UKemail: [email protected]

Mike JacksonDepartment of Geology and GeophysicsInstitute for Rock MagnetismUniversity of Minnesota100 Union Street SEMinneapolis, MN 55455, USAemail: [email protected]

Jack A. Jacobs (deceased)

Dominique JaultLGIT, CNRS and University Joseph-FourierBP 5338041Grenoble Cedex9, Franceemail: [email protected].

Malcolm J.S. JohnstonUSGS345 Middlefield Rd MS 977Menlo Park, CA 94025, USAemail: [email protected]

Chris JonesDepartment of Applied MathematicsUniversity of LeedsLeeds LS2 9JT, UKemail: [email protected]

Art R.T. JonkersDepartment of Earth and Ocean SciencesThe Jane Herdman LaboratoriesUniversity of Liverpool4 Brownlow StLiverpool, L69 3GP, UKemail: [email protected]

Tomoo KatsuraInstitute for Study of the Earth's InteriorOkayama UniversityMisasa, Tottori-ken, 682-0193, Japanemail: [email protected]

CONTRIBUTORS xix

Michael KendallDept of Earth SciencesUniversity of BristolQueen's Rd.Bristol, BS8 1RJ, UKemail: [email protected]

Brian KennettResearch School of Earth SciencesAustralian National UniversityGPO Box 4Canberra, ACT 0200, Australiaemail: [email protected]

David KerridgeGeomagnetism GroupBritish Geological Survey West Mains RoadEdinburgh, EH9 3LA, UKemail: [email protected]

Gunther KletetschkaNASA Goddard Space Flight CenterGreenbelt, Maryland, 20771, USAemail: [email protected]

Kenneth P. KodamaDepartment of Earth and Environmental SciencesLehigh University31 Williams Drive, Bethlehem, PA 18015-3188, USAemail: [email protected]

Masaru KonoInstitute for Study of the Earth's InteriorOkayama, University of MisasaYamada 827Misasa, Tottori Prefecture, 682 0193, Japanemail: [email protected]

Juha V. KorhonenGeological Survey of FinlandPOB 96Espo, 02151, Finlandemail: [email protected]

Andrei KosterovNikolaeva 5-56, Kiev, Ukraineemail: [email protected]/[email protected]

Pieter KotzéGeomagnetism GroupHermanus Magnetic ObservatoryPO Box 32, Hermanus, 7200, South Africaemail: [email protected]

David KrásaSchool of GeoSciencesUniversity of EdinburghKing's BuildingsEdinburgh, EH9 3JW, UKemail: [email protected]

Stéphane LabrosseDepartement des GeomateriauxInstitut de Physique du Globe de Paris4 place JussieuParis Cedex 05, 75252, Franceemail: [email protected]

Gurbax S. LakhinaIndian Institute of GeomagnetismNew Panvel, Navi Mumbai, 410218, Indiaemail: [email protected]

Thorne LayEarth Sciences Dept.University California Santa CruzSanta Cruz, CA 95064-1077, USAemail: [email protected]/[email protected]

Jean-Louis Le MouelInstitut de Physique du Globe de Paris4 place JussieuParis Cedex 05, 75252, Franceemail: [email protected]

Mark LesterDept. of Physics and AstronomyUniversity of LeicesterLeicester, LE1 7RH, UKemail: [email protected]

Shaul LeviCollege of Oceanic and Atmospheric SciencesOregon State UniversityCorvallis, OR 97331-5503, USAemail: [email protected]

Anyi LiLamont-Doherty Earth Observatoryand Department of Earth and Environmental SciencesColumbia UniversityPalisades, NY 10964, USAemail: [email protected]

Xinhao LiaoShanghai Astronomical Observatory80 Nandan RoadShanghai, 200030, China

Ted LilleyResearch School of Earth SciencesAustralian National UniversityGPO Box 4Canberra, ACT 0200, Australiaemail: [email protected]

Hans-Joachim LintheGeomagnetic Adolf Schmidt Observatory NiemegkGeoforschungszentrum PotsdamLindenstr. 714823 Niemegk, Germanyemail: [email protected]

Philip W. LivermoreSchool of MathematicsUniversity of LeedsLeeds, LS2 9JT, UKemail: [email protected]

David LoperFlorida State UniversityGFDI-4360Tallahassee, FL 32306-0000, USAemail: [email protected]

Jeffrey J. LoveUSGS GoldenBox 25045 MS966 DFCDenver, CO 80227, USAemail: [email protected]

Frank LowesDepartment of PhysicsThe University of Newcastle-upon-TyneNewcastle upon Tyne, NE1 7RU, UKemail: [email protected]

William LowrieInstitute of GeophysicsETH-HönggerbergCH-8093 Zürich, Switzerlandemail: [email protected]

Steve P. LundDepartment of Earth SciencesUniversity of Southern CaliforniaLos Angeles, CA 90089-0740, USAemail: [email protected]

xx CONTRIBUTORS

Susan MacmillanBritish Geological SurveyWest Mains RoadEdinburgh, EH9 3LA, UKemail: [email protected]

Barbara A. MaherCentre for Environmental Magnetism and PalaeomagnetismLancaster UniversityLancaster, LA1 4YB, UKemail: [email protected]

Stuart R.C. Malin30 Wemyss RoadBlackheathLondon, SE3 0TG, UKemail: [email protected]

Mioara MandeaGeoForschungZentrumTelegrafenberg14473 Potsdam, F269, Germanyemail: [email protected]

Guy MastersIGPP Scripps Institute of OceanographyUniversity of California, San Diego9500 Gilman DriveLa Jolla, CA 92093-0225, USAemail: [email protected]

Hiroaki MatsuiDept. Geophysical SciencesUniversity of Chicago5734 S. Ellis Ave.Chicago, IL 60637, USAemail: [email protected]

Stefan MausNational Geophysical Data CenterNOAA E/GC1325 BroadwayBoulder, CO 80305-3328, USAemail: [email protected]

Alain MazaudLaboratoire des Sciences du Climat et de l'Environnement (LSCE)CEA-CNRSAvenue de la TerrasseGif-sur-Yvette Cedex, 91198, Franceemail: [email protected]

Heather McCreadieWorld Data Centre for GeomagnetismKyoto UniversityKyoto, 606-8502, Japan

William F. McDonoughDepartment of GeologyUniversity of MarylandCollege Park, Maryland, 20742, USAemail: [email protected]

Michael W. McElhinnyGondwana Consultants31 Laguna PlacePort Macquarie, NSW 2444, Australiaemail: [email protected]@optusnet.com.au

Phillip L. McFaddenGeoscience AustraliaGPO Box 378Canberra, ACT 2601, Australiaemail: [email protected]

David G. McMillanDepartment of Earth & Space Science and EngineeringYork UniversityToronto, Ontario, Canadaemail: [email protected]

Maxwell A. MejuDept Environmental Sci.Lancaster UniversityUniversity Rd.Bailrigg, LA1 4YQ, UKemail: [email protected]

Ronald T. MerrillGeophysics Program, AK50University of WashingtonP.O. Box 433934Seattle, Washington 98195, USAemail: [email protected]

Leon MestelAstronomy CentreUniversity of SussexBrighton BN1 9QH, UKemail: [email protected]

Stephen MilanRadio and Space Plasma Physics GroupDepartment of Physics and AstronomyUniversity of LeicesterLeicester, LE1 7RH, UKemail: [email protected]

Thomas E. MooreLaboratory for Solar and Space PhysicsMail Code 612Greenbelt, MD 20771, USAemail: [email protected]

Andrea MorelliIstituto Nazionale di Geofisica e VulcanologiaVia Donato Creti 1240128 Bologna, Italyemail: [email protected]

Leslie V. Morrison28 Pevensley Park RoadWestham, PevensleyEast Sussex, BN24 5HW, UKemail: [email protected]

Bruce M. MoskowitzDepartment of Geology and GeophysicsUniversity of Minnesota310 Pillsbury Dr. SEMinneapolis, MN 55455, USAemail: [email protected]@bmosk.email.umn.edu

V. Rama MurthyDepartment of Geology and GeophysicsUniversity of Minnesota310 Pillsbury Drive SEMinneapolis, MN55455, USAemail: [email protected]

Adrian R. MuxworthyNational Oceanography CentreSchool of Ocean and Earth ScienceUniversity of SouthamptonSouthampton, SO14 3ZH, UKemail: [email protected]@soc.soton.ac.uk

Katherine A. NazarovaITSS/NASA Goddard Space Flight CenterGreenbelt, MD 20771, USAemail: [email protected]

Lawrence R. Newitt1 Observatory CrescentGeological Survey CanadaOttawa, ON K1A 0Y3, Canadaemail: [email protected]

CONTRIBUTORS xxi

Francis NimmoDept. Earth SciencesUniversity of CaliforniaSanta Cruz, CA 95064, USAemail: [email protected]

Nils OlsenDanish National Space CenterJuliane Maries VejCopenhagen, 2100, Denmarkemail: [email protected]

Peter OlsonEarth & Planetary SciencesThe Johns Hopkins UniversityBaltimore, MD 21218-2681, USAemail: [email protected]

Neil OpdykeDepartment of GeologyUniversity of Florida1112 Turlington HallGainsville, FL 32611, USAemail: [email protected]

Özden ÖzdemirDepartment of PhysicsUniversity of TorontoMississauga, Ontario L5L 1C6, Canadaemail: [email protected]

Eugene N. Parker1323 Evergreen RdHomewood, IL 60430, USAemail: [email protected]

Hanneke PaulssenUniversiteit UtrechtInstitute of Earth SciencesP O Box 80021Utrecht, 3508 TA, The Netherlandsemail: [email protected]

Louise PellerinGreen Engineering, Inc.6543 Brayton DriveAnchorage, AK 99507, USAemail: [email protected]

Klaus PetersenPetersen InstrumentsTorstr. 17310115 Berlin, Germanyemail: [email protected]

Nikolai PetersenDepartment of Earth and Environmental SciencesUniversity of MunichTheresienstr. 4180333 München, Germanyemail: [email protected]

Eduard PetrovskyGeophysical InstituteBocni II/1401Prague 4, 141 31, Czech Republicemail: [email protected]

Mark PilkingtonGeological Survey of Canada615 Booth StreetOttawa, ON, Canada, K1A 0E9email: [email protected]

John D.A. PiperDepartment of Earth SciencesGeomagnetism LaboratoryUniversity of LiverpoolLiverpool, L69 7ZEm, UKemail: [email protected]

Jiří PokornýAGICO, Inc.Advanced Geoscience Instruments CompanyJecna 29aBrno, CZ 621 00, Czech Republicemail: [email protected]

David PriceDepartment of Geological ScienceUniversity College LondonGower StreetLondon, WC1E 6BT, UKemail: [email protected]

Michael ProctorUniversity of CambridgeD.A.M.T.P, F1.07 CMSWilberforce Rd.Cambridge, CB3 0WA, UKemail: [email protected]@damtp.cam.ac.uk

Michael E. PuruckerGoddard Space Flight CentreGeodynamics BranchHughes-STXGreenbelt, MD 20771, USAemail: [email protected]

Karl-Heinz RaedlerAstrophysikalisches Institut PotsdamAndersternwarte 1614482 Potsdam, Germanyemail: [email protected]@arcor.de

Mita RajaramIndian Institute of GeomagnetismNew Panvel, Navi Mumbai, 410218, Indiaemail: [email protected]

Jean L. RassonCentre de Physique du GlobeInstitut Royal MétéorologiqueDourbes, 5670, Belgiumemail: [email protected]

Dhananjay RavatDepartment of Geology 4324Southern Illinois University CarbondaleCarbondale, IL 62901-4324, USAemail: [email protected]@siu.edu

Colin ReevesEarthworksAchterom 41aDelft, 2611PL, The Netherlandsemail: [email protected]

Alan B. Reid49 Carr Bridge DriveLeeds, LS16 7LB, UKemail: [email protected]

Karen J. RemickUSGS GoldenBox 25045 MS966 DFCDenver, CO 80227, USAemail: [email protected]

Paul G. RichardsLamont-Doherty Earth ObservatoryColumbia University61 Route 9WPalisades, NY 10964-1000, USAemail: [email protected]

xxii CONTRIBUTORS

Arthur D. RichmondNCARHigh Altitude ObservatoryPOB 3000Boulder, CO 80307-3000, USAemail: [email protected]

Oliver RitterGeoForschungsZentrumTelegrafenberg A4514473 Potsdam, Germanyemail: [email protected]

Andrew P. RobertsNational Oceanography CentreSchool of Ocean and Earth ScienceUniversity of SouthamptonSouthampton, SO14 3ZH, UKemail: [email protected]@soc.soton.ac.uk

Paul H. RobertsInstitute of Geophysics and Planetary PhysicsUCLA405 Hilgard AvenueLos Angeles, CA 90095, USAemail: [email protected]

Michael G. RochesterDept of Earth SciencesMemorial University of NewfoundlandSt. John's, N.L., A1B 3X5, Canadaemail: [email protected]

Pierre RochetteCNRS-Université d'Aix-Marseille 3CEREGE BP80 Europole de l'ArboisAix en Provence Cedex 4, 13545, Franceemail: [email protected]

Leonardo SagnottiIstituto Nazionale di Geofisica e VulcanologiaVia di Vigna Murata 605Roma, 00143, Italyemail: [email protected]

Graeme R. SarsonSchool of Mathematics and StatisticsUniversity of NewcastleNewcastle upon Tyne, NE1 7RU, UKemail: [email protected]

Armin SchmidtDepartment of Archaeological SciencesUniversity of BradfordBD7 1DP, UKemail: [email protected]

Jean-Jacques SchottEcole et Observatoire des Sciences de la Terre5, rue DescartesStrasbourg Cedex, 67084, Franceemail: [email protected]

Gerald SchubertDepartment of Earth & Space SciencesUniversity of California2707 Geology BuildingLos Angeles, CA 90024-1567, USAemail: [email protected]@ucla.edu

Adam SchultzCollege of Oceanic and Atmospheric SciencesOregon State UniversityCorvallis, OR 97331-5503, USAemail: [email protected]

Johannes SchweitzerNORSARInstituttveien 25POB 53Kjeller, 2027, Norwayemail: [email protected]

Gary R. ScottBerkeley Geochronology Center2455 Ridge RoadBerkeley, CA 95709, USAemail: [email protected]

John ShawDepartment of Earth SciencesUniversity of LiverpoolOxford Street, P.O. Box 147Liverpool, L69 3BX, UKemail: [email protected]

Guoyin ShenCenter for Advanced Radiation SourcesUniversity of ChicagoChicago, IL 60439, USAemail: [email protected]

Manfred SiebertInstitute of GeophysicsUniversity of GöttingenFriedrich-Hund-Platz 137077 Göttingen, Germany

Brad S. SingerDepartment of Geology and GeophysicsUniversity of Wisconsin-Madison1215 West Dayton StreetMadison, WI 53706, USAemail: [email protected]

Alexei V. SmirnovDepartment of Earth and Environmental SciencesUniversity of RochesterHutchison Hall 227Rochester, NY 14627, USAemail: [email protected]

Xiaodong SongDept. of GeologyUniversity of Illinois1301 W. Green St. 245NHBUrbana, IL 61801, USAemail: [email protected]

Annie SouriauCNRSObservatoire Midi-Pyrenees14 Ave. Edouard BelinToulouse, 31400, Franceemail: [email protected]

Andrew SowardSchool of Mathematical SciencesUniversity of ExeterExeter, EX4 4QE, UKemail: [email protected]

Frank D. StaceyCSIRO Exploration and MiningPO Box 883Kenmore, Queensland 4069, Australiaemail: [email protected]

F. Richard StephensonDept. of PhysicsUniversity of DurhamSouth RoadDurham, DH1 3LE, UKemail: [email protected]

CONTRIBUTORS xxiii

David J. StevensonCALTECHDiv Geology & Planetary Sci, 150-21Pasadena, CA 91125, USAemail: [email protected]

John A. TardunoDepartment of Earth and Environmental SciencesUniversity of RochesterHutchison Hall 227Rochester, NY 14627, USAemail: [email protected]@volterra.earth.rochester.edu

Donald D. TarlingDepartment of Geological SciencesPlymouth PolytechnicDrake CircusPlymouth, Devon, PL4 8AA, UKemail: [email protected]

Patrick T. TaylorLaboratory for Planetary GeodynamicsNASA/Goddard Space Flight CenterGreenbelt, MD 20771, USAemail: [email protected]

Z.S. Teweldemedhin (no address)

Michael J. ThompsonDept. of Applied MathematicsUniversity of SheffieldSheffield, S3 7RH, UKemail: [email protected]

Alan W.P. ThomsonBritish Geological SurveyWest Mains RoadEdinburgh, EH9 3LA, UKemail: [email protected]

Michael ThorneDepartment of Geological SciencesArizona State UniversityTempe, AZ 85287-1404, USA

Andreas TilgnerInstitute of GeophysicsUniversity of GottingenHerzberger Landstr. 18037075 Göttingen, Germanyemail: [email protected]

Maurice A. TiveyDept Geology & GeophysicsWHOI360 Woods Hole RdWoods Hole, MA 02543-1542, USAemail: [email protected]

Steven M. TobiasDepartment of Applied MathematicsUniversity of LeedsLeeds, LS2 9JT, UKemail: [email protected]

Lester A. TomlinsonGeoscience, Electronics & Data Services30 Kirner St.Christchurch, 8009, New Zealandemail: [email protected]

Miquel TortaObservatori de l'EbreRoquetes (Tarragona), 43520, Spainemail: [email protected]

John B. TownshendUSGSBox 25046 MS 966Golden, CO 80225, USA

Oleg TroshichevArctic and Antarctic Research Institute38 Bering St.St. Petersburg, 199397, RUSSIAemail: [email protected]

Bruce T. TsurutaniJet Propulsion LaboratoryCalifornia Institute of Technology4800 Oak Grove DrivePasadena, CA 91009, USAemail: [email protected]

Agustín UdíasFacultad de Ciencias FísicasDepartamento de GeofísicaUniversidad ComplutenseCiudad UniversitariaMadrid, 28040, Spainemail: [email protected]

Martyn UnsworthUniversity of AlbertaEdmonton, Alberta, T6G 2J1, Canadaemail: [email protected]

Jaime Urrutia-FucugauchiInstituto de Geofisica, Laboratorio de Paleomagnetismo yPaleoambientesUniversidad Nacional Autonoma de MexicoMexico D.F., 04510, Mexicoemail: [email protected]

Jean-Pierre ValetInstitut de Physique du Globe de Paris4 place JussieuParis Cedex 05, 75252, Franceemail: [email protected]

Lidunka VočadloDept. Earth SciencesUniversity College LondonGower St.London, WC1E 6BT, UKemail: [email protected]

Ingo WardinskiGeoForschungsZentrum PotsdamSektion 2.3 Geomagnetische FelderTelegrafenberg14473 Potsdam, Germanyemail: [email protected]

Deanis WeaireDepartment of PhysicsTrinity CollegeCollege GreenDublin 2, Irelandemail: [email protected]

Peter D. WeilerBaseline Environmental Consulting5900 Hollis StreetEmeryville, CA 94608, USAemail: [email protected]

Kathryn A. WhalerGrant Institute of Earth ScienceThe University of EdinburghWest Mains RoadEdinburgh, EH9 3JW, UKemail: [email protected]

Quentin WilliamsEarth SciencesUCSCSanta Cruz, CA 95064, USAemail: [email protected]

xxiv CONTRIBUTORS

Wyn WilliamsDepartment of Geology & GeophysicsUniversity of EdinburghWest Mains RoadEdinburgh, EH9 3JW, UKemail: [email protected]

Ashley P. WillisDept of MathematicsUniversity of BristolBristol, BS8 1TW, UKemail: [email protected]

Denis WinchSchool of Mathematics & Statistics F07University of SydneySydney, NSW 2006, Australiaemail: [email protected]@maths.usyd.edu.au

Dongmei YangInstitute of GeophysicsChina Earthquake Administration, No. 5MinzudaxuenanluHaidan District, Beijing, 100081, Chinaemail: [email protected]

Keke ZhangDepartment of Mathematical SciencesUniversity of ExeterExeter, EX4 4QE, UKemail: [email protected]

Xixi ZhaoInstitute of Geophysics and Planetary PhysicsUniversity of California Santa Cruz1156 High StreetSanta Cruz, CA 95064, USAemail: [email protected]@es.ucsc.edu

Preface

Geomagnetism is the study of the earth's magnetic field: itsmeasurement, variation in time and space, origins, and its use inhelping us to understand more about our Earth. Paleomagnetism is thestudy of the record left in the rocks; it has contributed much to ourunderstanding of the geomagnetic field's past behavior and many otheraspects of geology and earth history. Both have applications, pure andapplied: in navigation, in the search for minerals and hydrocarbons, indating rock sequences, and in unraveling past geologic movementssuch as plate motions. The entire subject is a small subdiscipline ofearth science, and our goal has been to cover it in fine detail at a levelaccessible to anyone with a general scientific education. We envisagethe encyclopedia to be of greatest use to those starting in the subjectand those needing to know something of the field for their ownapplication, but the topic is broad and demanding—as we have becomeincreasingly aware while editing the huge variety of contributions—and we also expect it to be of use to experts in geomagnetism orpaleomagnetism who need to stray outside their own area of expertise,for nobody is an expert in the whole field.The scope of the encyclopedia is defined by the “GP” section of the

American Geophysical Union: the magnetic field of internal origin.Over 25% of the membership of GP has contributed to this book.External sources of magnetic field are included insofar as they are usedin solid earth geomagnetism—for example periodic external fields,because they induce electric currents in the earth that are useful inmapping deep electrically conducting regions—and articles areincluded on the ionosphere, magnetosphere, Sun, and planets. Externalgeomagnetism as such is a separate discipline in most researchestablishments as well as the AGU, and is therefore not treated.Geomagnetism is the oldest earth science, having its origins in

simple human curiosity in the lodestone's ability to point north. Itclaims what most believe to be the first scientific treatise, WilliamGillbert's (q.v.) De Magnete published in 1601, the claim beingfounded on its use of deduction from experimental measurement.These innocent beginnings were soon to give way to the intenselypractical business of finding one's way at sea, and during the Europeanage of discovery understanding the geomagnetic field and using it fornavigation became a burning challenge for early scientists. A centuryafter the publication of De Magnete saw Edmond Halley (q.v.) incharge of a Royal Navy vessel making measurements throughoutthe Atlantic Ocean. Halley's plans to fix position more accurately byusing the departures of magnetic north from geographic north weredashed by the geomagnetic field's rapid changes in time, and thelongitude problem was of course finally solved by Harrison and hisaccurate clock, but the compass remains an essential aid to navigationto this day.Almost a century after Halley's voyages James Cook was making

even more accurate measurements throughout the oceans, and in the19th century, Alexander von Humboldt (q.v.) and Carl Friedrich Gauss(q.v.) set up a network of magnetic observatories, the first example ofinternational cooperation in a scientific endeavor. The data compilationcontinued throughout the 19th century, with typical Victorian tenacity,led by Edward Sabine (q.v.), and detailed magnetic measurements weremade by James Clark Ross’ expedition to the poles and the voyage ofHMS Challenger. Impressive though these data collections were, with

hindsight they yielded rather little in the way of pure scientificdiscovery or useful application. True, Sabine was to identify the sourceof magnetic storms with activity on the Sun and they left us awonderful record of the geomagnetic field in the 19th century, layingthe foundation for modern surveying, but the real prize of discoveringthe geomagnetic field's origin eluded them.

Developments in the early 20th century were to catapult geomagnet-ism into the limelight yet again, this time in the quest for minerals. Metalores, base and noble, are concentrated in rocks rich in magnetites thatare intensely magnetic. Geomagnetism provided a cheap and simpleprospecting tool for exploration, and magnetic surveys proliferatedon land as never before. Geomagnetism provides the cheapestgeophysical exploration tool, and while it may lack the precision ofseismic methods it continues to produce economic returns—a year'sprofit from one of the larger mines would probably pay for all themapping in the last century. The discovery of electromagnetic inductionprovided yet another technique for exploring the earth's interior andeven more significantly it changed prevailing views on the origin ofgeomagnetic fluctuations and the earth's main dipole field. The manytheories for the origin proposed around the turn of the 20th century arereviewed here by David Stevenson (see Nondynamo theories). The onlyone to survive the test of time was Joseph Larmor's (q.v.) self-excitingdynamo theory, but even this was to suffer a half-century setbackfrom Thomas Cowling's (q.v.) proof that no dynamo could sustain amagnetic field with symmetry about an axis, which the earth's dipolehas to a good approximation.

Spectacular progress was being made at about this time by Frenchphysicists such as Bernard Brunhes and Motonori Matuyama (q.v.)from Japan trying to understand the magnetic properties of rocks. Infounding the science of paleomagnetism they discovered they wereable to determine the direction of the earth's magnetic field at the timeof the rock's formation, and made the astonishing discovery that themagnetic field had reversed direction in the past. This discovery, likethe dynamo theory, suffered a setback when, in the late 1950s, SeiyaUyeda and Takesi Nagata from Japan found that some minerals reversespontaneously: this providing an alternative but rather mundaneexplanation that appealed to some in a skeptical scientific community.Evidence for polarity reversals mounted, thanks in great part to theefforts of Keith Runcorn (q.v.) and colleagues in England, but itrequired precise radiometric dating and access to a suite of rocksyounger than 5 million years to establish a complete chronology andput the question beyond any doubt: this was finally achieved by AllanCox (q.v.) and colleagues in the USA in 1960, on the eve of the platetectonic revolution.

It is hard to comprehend the rapidity of scientific developmentsin earth science in the 1960s and impossible to underestimate theimportance of the role played by paleomagnetism and geomagnetismin the development of plate tectonics. The establishment of polarityreversals came together with H. Hess’ ideas on seafloor spreading andthe discovery of magnetic stripes on the ocean floor to provide a meansto map the age of the oceans (see Vine-Matthews-Morley hypothesis)and confirm once and for all Wegener's ancient ideas of continentaldrift. Even today, almost all our quantitative knowledge of platemovements in the geological past comes from paleomagnetism and

xxvi PREFACE

geomagnetism and the development of a reversal timescale (q.v. seealso Bill Lowrie's article Geomagnetic polarity timescales). 1958 sawat last the removal of Cowling's objection to the dynamo theory(see Dynamo, Backus and Dynamo, Herzenberg) and work done inEastern Europe and the former Soviet Union provided the mathema-tical foundation and physical insight needed to understand howthe geomagnetic field could be generated in the earth's liquid ironcore (see Dynamos, mean-field and Dynamo, Braginsky). Improve-ments in instrumentation accelerated magnetic surveys: electromag-netic surveys became routine, proton magnetometers could be towedbehind ships, and Sputnik ushered in the satellite era with amagnetometer on board.So where does geomagnetism and paleomagnetism stand now? The

dynamo theory of the origin of the main field still presents one of themost difficult challenges to classical physics, but computers are nowfast enough to solve the equations of magnetohydrodynamics (q.v., seealso Geodynamo, numerical simulations) in sufficient complexity toreproduce many of the observed phenomena; we have just entered adecade of magnetic observation with two satellites operational at thetime of writing and two more launches planned in the near future; thereare more aircraft devoted to industrial magnetic surveying than everbefore; electromagnetic methods have found application in the searchfor hydrocarbon reserves and have moved into the marine environment(see EM, marine controlled source). Paleomagnetists have begun tomap details of the magnetic field during polarity transition (seeGeomagnetic polarity reversals), discover many examples of excur-sions (aborted reversals), are mapping systematic departures from thesimple dipole structure, and have automated laboratory techniques tothe point where, in a single day, they can make more measurements ofthe absolute paleointensity of magnetic materials such as ceramics andbasaltic rocks than pioneer Emile Thellier (q.v.) could do in a lifetime(see articles on Absolute paleointensity).The subject divides naturally into the studies of magnetic fields with

different origins—indeed these differences often make it difficult evenfor experts to understand other branches of their own subject! Thosestudying the permanent magnetization of the earth's crustal rocks deal

with magnetic fields that owe their origin to permanent magnetism atthe molecular or crystal grain level; those in electromagnetic inductionstudy magnetic fields caused by electric currents induced in solid rocksdeep inside the Earth; while dynamo theorists deal with induction by afluid, and have to deal with the additional complexity of advection by amoving conductor. Paleomagnetism naturally separates into studies ofthe magnetism of rocks, or rock magnetism (q.v.), laboratory methodsfor determining the ancient field, and the history of the ancient fielditself. This classification dictated our choice of topics. Special efforthas been made to represent the activities of the global network ofpermanent magnetic observatories. These rarely feature in scientificpapers and most practicing scientists are unaware of the meticulousnature of the work and the dedication of those unsung heroes chargedwith maintaining standards over decades—a persistence rarelyexperienced in modern science. The observatory section represents,to our knowledge, the first attempt to draw together into one place thisrather loosely connected international endeavor.

Our subject relates to many other disciplines, either because thegeomagnetic field is a vital part of our environment and provides asurprising range of useful techniques to others, from stratigraphythrough navigation to radio communication. Partly because of this, andpartly in an effort to provide a self-contained volume, we have strayedoutside the strict remit of GP. We have included articles on earthstructure, particularly those esoteric regions (see for example articleson D”) important for geomagnetism, and have covered the fascinatingmagnetic fields of other planets and satellites.

Our main thanks must go to our contributors, who have so willinglyand energetically contributed to make this a truly community effort: wehave received very few refusals to our requests to contribute. AlanJones and Kathryn Whaler advised on electromagnetic induction, adifficult subject for both editors. Thanks go to Stella Gubbins for herunstinting work in organizing the geomagnetism articles and present-ing them to the publishers in good order.

March 2007David Gubbins and Emilio Herrero-Bervera