Volcanism on Io : a comparison with Earth

390 Pages·2007·8.152 MB·English

by  Ashley Gerard Davies.

VOLCANISM ON IO
AComparisonwithEarth
ThemostpowerfulvolcanoesintheSolarSystemarefoundnotonEarthbutonIo,
a tiny moon of Jupiter. Earth and Io are the only bodies in the Solar System with
active,high-temperaturevolcanoes,butvolcanoesonIoarelargerandhotter–as
wellasmoreviolent.
Thisbook,thefirstdedicatedtovolcanismonIo,containsthelatestresultsfrom
the Galileo mission. In addition to investigating the different styles and scales of
volcanic activity on Io, it compares those volcanoes to their contemporaries on
Earth. The book also provides background on how volcanoes form and how they
erupt, and explains quantitatively how remote-sensing data from spacecraft and
telescopesareanalyzedtorevealunderlyingvolcanicprocesses.
Thisrichlyillustratedbookwillbeafascinatingreferenceforadvancedunder-
graduate and graduate students, as well as researchers in planetary sciences, vol-
canology,remotesensing,andgeology.
A D isavolcanologistattheJetPropulsionLaboratory–California
Institute of Technology in Pasadena, California. He was a member of the Galileo
Near-Infrared Mapping Spectrometer Team, is Principal Investigator on several
studies investigating volcanic activity on Io and Earth, and was a recipient of the
2005NASASoftwareoftheYearAwardforhisworkonspacecraftautonomy.

VOLCANISM ON IO
A Comparison with Earth
ASHLEY GERARD DAVIES
JetPropulsionLaboratory–CaliforniaInstituteofTechnology

Cambridge,NewYork,Melbourne,Madrid,CapeTown,Singapore,Sa˜oPaulo
CambridgeUniversityPress
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(cid:1) A.G.Davies2007
Thispublicationisincopyright.Subjecttostatutoryexception
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noreproductionofanypartmaytakeplacewithout
thewrittenpermissionofCambridgeUniversityPress.
Firstpublished2007
PrintedintheUnitedKingdomattheUniversityPress,Cambridge
AcataloguerecordforthispublicationisavailablefromtheBritishLibrary
LibraryofCongressCataloginginPublicationdata
Davies,AshleyGerard,1961–
VolcanismonIo:acomparisonwithEarth/byAshleyGerardDavies.
p. cm.
Includesbibliographicalreferencesandindex.
ISBN-13:978-0-521-85003-2
ISBN-10:0-521-85003-7
1.Io(Satellite)–Volcanism. 2.Io(Satellite)–Volcanoes. 3.Planetaryvolcanism–Remotesensing.
4.Volcanism. I.Title.
QB404.D38 2007
551.210999(cid:2)25–dc22 2006037426
ISBN-13 978-0-521-85003-2hardback
CambridgeUniversityPresshasnoresponsibilityforthepersistenceoraccuracyofURLsforexternalor
third-partyInternetWebsitesreferredtointhispublication,anddoesnotguaranteethatanycontent
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Contents
Preface page xi
ListofAbbreviations xiii
ReproductionPermissions xv
Introduction 1
Section1 Io,1610to1995:GalileotoGalileo
1 Io,1610–1979 7
1.1 IobeforeVoyager 7
1.2 Predictionofvolcanicactivity 9
1.3 VoyagertoJupiter 9
1.4 Discoveryofactivevolcanism 12
1.5 IRISandvolcanicthermalemission 18
1.6 Io:theviewafterVoyager 19
1.7 Summary 24
2 BetweenVoyagerandGalileo:1979–1995 27
2.1 SilicatevolcanismonIo? 27
2.2 Ground-basedobservations 29
2.3 ObservationsofIofromEarthorbit 33
2.4 ThePeleplume 33
2.5 Outbursteruptions 34
2.6 Stealthplumes 37
2.7 IoontheeveofGalileo 38
3 GalileoatIo 39
3.1 Instrumentation 41
3.2 GalileoobservationsofIo 46
Section2 Planetaryvolcanism:evolutionandcomposition
4 IoandEarth:formation,evolution,andinteriorstructure 53
4.1 Globalheatflow 53
4.2 Planetaryformation 55
v
vi Contents
4.3 Post-formationheating 58
4.4 Interiorstructure 63
4.5 Volcanismovertime 70
4.6 Implications 72
5 Magmasandvolatiles 73
5.1 Basalt 73
5.2 Ultramaficmagma 74
5.3 Lavarheology 76
5.4 Sulphur 78
5.5 Sulphurdioxide(SO ) 86
2
Section3 Observingandmodelingvolcanicactivity
6 Observations:thermalremotesensingofvolcanicactivity 93
6.1 RemotesensingofvolcanicactivityonEarth 93
6.2 RemotesensingofvolcanicactivityonIo 95
6.3 Remotesensingofthermalemission 96
6.4 Blackbodythermalemission 97
6.5 Multi-spectralobservations 98
6.6 The“dual-band”technique 99
6.7 Surfacetemperaturedistributionsandeffectonthermal
emission 102
6.8 Hyperspectralobservations 102
6.9 Analysisofhyperspectralthermalemissiondata 102
6.10 AnalysisofSSIthermalemissiondata 107
7 Modelsofeffusiveeruptionprocesses 108
7.1 CoolingoflavaonEarthandIo 109
7.2 Modelinglavasolidificationandcooling 114
7.3 Volumetricrates(Q andQ ) 127
F E
7.4 Modelsoflavaemplacement 132
7.5 Supplytothesurface:conduitgeometry 134
7.6 CrustalstructurecontrolsonascentofmagmaonIo 137
8 Thermalevolutionofvolcaniceruptions 142
8.1 Effusiveactivity:landformsandthermalemission
evolution 143
8.2 Fluxdensityasafunctionoferuptionstyle 150
8.3 Summary 152
Section4 GalileoatIo:thevolcanicbestiary
9 TheviewfromGalileo 155
9.1 Surfacechanges:VoyagertoGalileo 156
9.2 Colorandcomposition 159
Contents vii
9.3 Discoveryofwidespreadsilicatevolcanism 165
9.4 Therise(andfall?)ofultra-high-temperaturevolcanism 169
9.5 PPRobservations 175
9.6 CassiniandGalileoobserveIo 176
9.7 AdaptiveopticsandHubbleobservations 176
9.8 Otherdiscoveries 177
9.9 Summary 177
10 ThelavalakeatPele 178
10.1 Setting 178
10.2 Observationsofthermalemission 179
10.3 AlavalakeatPele 182
10.4 Importanceoftemporalandspectralcoverage 183
10.5 Lavalakes 184
10.6 Implicationsformagmasupplyandinteriorstructure 185
10.7 Plumecompositionandimplicationsforvolatilesupply 185
10.8 Calculationofmassfluxandfluxdensities 186
10.9 FurthercomparisonwithlavalakesonEarth 187
10.10 Summary 190
11 PillanandTvashtarPaterae:lavafountainsandflows 192
11.1 Lavafountains:outburstsexplained? 192
11.2 Pillan1997:floodlavasandtheemplacementoflong
flows 194
11.3 TvashtarPaterae 200
11.4 LavafountainsonIo 201
11.5 Terrestrialanalogues:floodbasaltsandfissureeruptions 202
11.6 Pillancomparisonswithterrestrialeruptions 204
11.7 Summary:activityatPillanin1997andatTvashtar
Pateraein2000 205
12 PrometheusandAmirani:effusiveactivityandinsulatedflows 208
12.1 VolcanicactivityatPrometheus 208
12.2 ComparisonwithPu’u’O’o-Kupaianaha,Hawai’i 213
12.3 Amiraniflowfield 215
12.4 Discussionandsummary 216
13 LokiPatera:Io’spowerhouse 217
13.1 VoyagertoGalileo 218
13.2 Styleofactivity 219
13.3 Temporalbehavior 220
13.4 ResurfacingofLokiPatera 222
13.5 Modelingtheresurfacingprocess 225
viii Contents
13.6 MagmavolumeatLokiPatera 227
13.7 Summary:aclassofitsown 228
14 Othervolcanoesanderuptions 229
14.1 TupanPatera 229
14.2 CulannPateraandenvirons 230
14.3 Zamama 230
14.4 GishBarPatera 232
14.5 EmakongPatera:sulphurvolcanism? 232
14.6 BalderandAbabiniliPaterae:SO flows? 234
2
14.7 TheplumesofSurtandThor 234
Section5 VolcanismonIo:theglobalview
15 Geomorphology:paterae,shields,flows,andmountains 239
15.1 PateraeonIoandcalderasonEarth 239
15.2 Shieldvolcanoes 245
15.3 Lavaflowmorphology 249
15.4 Lavachannels 250
15.5 Mountainsandformationmechanisms 251
15.6 Conclusions 252
16 Volcanicplumes 253
16.1 ExplosiveactivityonIoandEarth 253
16.2 Ioobservations 256
16.3 Plumetypes 257
16.4 Plumemodels 267
16.5 Summary 268
17 Hotspots 269
17.1 Variabilityandstyleofactivity 270
17.2 Thermalemissioncomparisons 276
17.3 Effusionrates 277
17.4 Distributionofhotspots 278
17.5 Heattransportbyeruptionclass 280
Section6 IoafterGalileo
18 VolcanismonIo:apost-Galileoview 287
18.1 Volcanismandcrustalstructure 287
18.2 Magmacomposition 288
18.3 Crustvolatilecontent 289
18.4 Hot-spotvariability 290
18.5 Eruptionstyles 290
18.6 Plumes 291
18.7 VolcanismonIoandEarth 292
18.8 Questions 292