Meso-scale shear physics in earthquake and landslide mechanics

280 Pages·2010·16.192 MB·vii, 285 p. : ill. ; 25 cm\280

by  Yossef H Hatzor, J Sulem, I Vardoulakis

MESO-SCALESHEARPHYSICSINEARTHQUAKEANDLANDSLIDEMECHANICS
© 2010 by Taylor and Francis Group, LLC
Meso-Scale Shear Physics in
Earthquake and Landslide Mechanics
Editors
Yossef H. Hatzor
DepartmentofGeologicalandEnvironmentalSciences,
Ben-GurionUniversityoftheNegev,Beer-Sheva,Israel
Jean Sulem
UniversitéParis-Est,EcoledesPontsParisTech,
URNavier,CERMES,ChampssurMarne,France
Ioannis Vardoulakis
FacultyofAppliedMathematicsandPhysics,DepartmentofMechanics,
NationalTechnicalUniversityofAthens,Athens,Greece

© 2010 by Taylor and Francis Group, LLC
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LibraryofCongressCataloging-in-PublicationData
Meso-scaleshearphysicsinearthquakeandlandslidemechanics/editors,YossefH.Hatzor,Jean
Sulem,IoannisVardoulakis.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN 978-0-415-47558-7 (hardcover : alk. paper) -- ISBN 978-0-203-86290-2 (e-book)
1. Deformations (Mechanics) 2. Shear (Mechanics) 3. Faults (Geology) 4. Earthquakes.
5.Landslides.I.Hatzor,YossefH.II.Sulem,J.(Jean)III.Vardoulakis,I.(Ioannis)IV.Title.
QE604.M472010
551.22--dc22
2009028817
ISBN:978-0-415-47558-7(Hbk)
ISBN:978-0-203-86290-2(Ebook)
© 2010 by Taylor and Francis Group, LLC
Table of contents
Preface vii
I. Dynamicsoffrictionalslip
1. Thermo-andhydro-mechanicalprocessesalongfaultsduringrapidslip 3
J.R.Rice,E.M.Dunham&H.Noda
2. Slipsequencesinlaboratoryexperimentsasanaloguestoearthquakes
associatedwithafaultedge 17
S.M.Rubinstein,G.Cohen,J.Fineberg&Z.Reches
3. Onthemechanismofjunctiongrowthinpre-sliding 25
A.Ovcharenko,G.Halperin&I.Etsion
4. Nanoseismicmeasurementofthelocalizedinitiationofslidingfriction 31
G.McLaskey&S.D.Glaser
5. Weaklynonlinearfracturemechanics:Experimentsandtheory 43
E.Bouchbinder,A.Livne&J.Fineberg
II. Faultgaugemechanics
6. Theeffectofmineraldecompositionasamechanismoffaultweakening
duringseismicslip 57
J.Sulem&V.Famin
7. Thermalmechanismsandfrictionlawsdeterminingthestability
andlocalizationduringslipweakeningofshallowfaults 69
E.Veveakis,S.Alevizos&I.Vardoulakis
8. Cataclasticandultra-cataclasticshearusingbreakagemechanics 77
I.Einav&G.D.Nguyen
III. Experimentalfaultzonemechanics
9. Strainlocalizationingranularfaultzonesatlaboratoryandtectonicscales 91
C.J.Marone&A.Rathbun
10. Somenewexperimentalobservationsonfractureroughnessanisotropy 105
G.Grasselli
11. Constraintsonfaultingmechanismsusing3Dmeasurementsofnaturalfaults 117
A.Sagy&E.E.Brodsky
12. Nonlinearelasticityandscalardamagerheologymodelforfracturedrocks 123
V.Lyakhovsky&Y.Hamiel
13. Damagerheologyandstableversusunstablefracturingofrocks 133
Y.Hamiel,V.Lyakhovsky,O.Katz,Y.Fialko&Z.Reches
V
© 2010 by Taylor and Francis Group, LLC
VI Tableofcontents
14. Micro-scaleroughnesseffectsonthefrictioncoefficientofgranite
surfacesundervaryinglevelsofnormalstress 145
O.Biran,Y.H.Hatzor&A.Ziv
IV. Granularshearandliquefaction
15. Frictioningranularmedia 159
J.C.Santamarina&H.Shin
16. Whatcontrolstheeffectivefrictionofshearinggranularmedia? 191
M.Nataliya,L.Goren,D.Sparks&E.Aharonov
17. Porepressuredevelopmentandliquefactioninsaturatedsand 205
S.Frydman,M.Talesnick,A.Mehr&M.Tsesarsky
18. Characterizinglocalizationprocessesduringliquefactionusing
inverseanalysesofinstrumentationarrays 219
R.Kamai&R.Boulanger
19. OnseismicP-andS-wavevelocitiesinunconsolidatedsediments:Accounting
fornon-uniformcontactsandheterogeneousstressfieldsintheeffective
mediaapproximation 239
R.Bachrach&P.Avseth
V. Dynamicsoflandslides
20. Thermo-poro-mechanicaleffectsinlandslidedynamics 255
L.Goren,E.Aharonov&M.Anders
21. Mechanismsoffluidoverpressurizationrelatedtoinstabilityof
slopesonactivevolcanoes 275
D.Elsworth,B.Voight&J.Taron
Authorindex 285

© 2010 by Taylor and Francis Group, LLC
Preface
This book brings together a collection of invited articles on meso-scale mechanics, as a means
to develop an understanding of the underlying physics dominating shear at material interfaces
andwithinparticulatesystemsduringconditionsofrapidshearing.Thiseditedvolumeemanated
from the ‘‘Batsheva Seminar on Shear Physics at the Meso-scale in Earthquake and Landslide
Mechanics’’,sponsoredbytheBatshevadeRothschildfundoftheIsraelAcademyofSciencesand
Humanitiesandco-sponsoredjointlybytheUSAirForceResearchLaboratoryandtheBen-Gurion
UniversityoftheNegev.
Identificationofmeso-scalephenomenaoccurringbetweenmicroscopicandcontinuumlength
scaleshasbeenoneofthemostexcitingdevelopmentsinthelastdecadesinunderstandingshear
betweenmaterialinterfacesandinparticulatesystems,andisconsideredasthebridgebetweenthe
twolengthscalesforstudyingmaterialresponse.Atthemeso-scalecomplexitiesariseduetothe
presenceofstructuralelementslikesurfaceroughness,grains,internalboundariesbetweenthem,
physical phenomena occurring at surfaces, formation of sub-grain elements during loading, the
presenceoffluids,interactionbetweendifferentmaterials,andtheircombinedeffectontheresponse
ofthesystem.ThisresearchareahasbroadapplicationsinGeosciencesandGeoengineering.For
example, the initiation of seismic slip along fault planes at great depths at rates nearing shock
conditionsandtheinitiationofdeepseatedlandslidesneartheearth’ssurface.Additionally,thebasic
physicsofthermo-poro-mechanicalcouplingcanbeelucidatedthroughameso-scalemechanics
approach as a means of understanding the loss of shearing resistance when water and heat are
trappedinsidealmostimperviousshearlayersundergreatpressures. Inthecaseofseismicslip,
tremendousamountofmaterialslipsatveryhighvelocities(severalmeterspersecond)onultra
localizedshearzones.Shearheatingandfluidpressurizationcanbeassociatedtophenomenasuch
asphasetransitionandmineraldecompositionandthusplayakeyroleintheunderstandingofthe
energeticsofearthquakes.Inthecaseofdeepseatedlandslides,thermo-poro-mechanicalprocesses
withinlocalizedshearzonescontroltheirtriggering,theirslidingvelocityandconsequentlytheir
runout.
The21,peer-reviewedarticlesaregroupedintofivechaptersthataddresstheoretical,compu-
tationalandexperimentalaspectsofmeso-scalemechanicsofmaterialinterfacesandparticulate
systemsasfollows:1)Dynamicsoffrictionalslip,2)Faultgaugemechanics,3)Experimentalfault
zonemechanics,4)Granularshearandliquefaction,and5)Dynamicsoflandslides.
WewishtoexpressourdeepgratitudetoDr.YossiSegal,SecretaryofNaturalSciences,Israel
AcademyofSciences;Dr.MajorWynnS.Sanders,ChiefofMaterialsandNanotechnology,Euro-
pean Office of Aerospace Research and Development—USAF, Professor Rivka Carmi (M.D.),
President, Ben-Gurion University of the Negev, Professor Jimmy Weinblatt, Rector, BGU, and
ProfessorAmirSagi,Dean,FacultyofNaturalSciences,BGU,fortheirfinancialsupport.Finally,
wealsowishtothankDr.ConradFeliceofWashingtonStateUniversityforcochairingtheBatsheva
seminarandforhisresourcefulassistancethroughouttheproductionoftheseminar.
YossefH.Hatzor
JeanSulem
IoannisVardoulakis
Editors
VII
© 2010 by Taylor and Francis Group, LLC
I. Dynamics of frictional slip
© 2010 by Taylor and Francis Group, LLC
Thermo- and hydro-mechanical processes along faults during rapid slip
JamesR.Rice
DepartmentofEarthandPlanetarySciencesandSchoolofEngineeringandAppliedSciences,
HarvardUniversity-SEAS,Cambridge,MA,USA
EricM.Dunham
DepartmentofGeophysics,StanfordUniversity,Stanford,CA,USA
HiroyukiNoda
DivisionofGeologicalandPlanetarySciences,
CaliforniaInstituteofTechnology,Pasadena,CA,USA
ABSTRACT: Field observations of maturely slipped faults show a generally broad zone of
damage by cracking and granulation. Nevertheless, large shear deformation, and therefore heat
generation, inindividualearthquakestakesplacewithextremelocalizationtoazone <1–5mm
widewithinafinelygranulatedfaultcore.Relevantfaultweakeningprocessesduringlargecrustal
eventsarethereforelikelytobethermal.Further,giventheporosityofthedamagezones,itseems
reasonabletoassumegroundwaterpresence.Itissuggestedthatthetwoprimarydynamicweak-
eningmechanismsduringseismicslip,bothofwhichareexpectedtobeactiveinatleasttheearly
phasesofnearlyallcrustalevents,arethenasfollows:(1)Flashheatingathighlystressedfrictional
micro-contacts,and(2)Thermalpressurizationoffault-zoneporefluid.Bothhavecharacteristics
whichpromoteextremelocalizationofshear.Macroscopicfaultmeltingwilloccuronlyincasesfor
whichthoseprocesses,orotherswhichmaysometimesbecomeactiveatlargeenoughslip(e.g.,
thermal decomposition, silica gelation), have not sufficiently reduced heat generation and thus
limitedtemperaturerise.Spontaneousdynamicrupturemodeling,usingproceduresthatembody
mechanisms(1)and(2),showshowfaultscanbestaticallystrongyetdynamicallyweak,andoper-
ateunderlowoveralldrivingstress, inamannerthatgeneratesnegligibleheatandmeetsmajor
seismicconstraintsonslip,stressdrop,andself-healingrupturemode.
1 INTRODUCTION
Therehasbeenasurgeofactivityinrecentyearstowardsincreasedphysicalrealismindescription
oftheearthquakeprocess.Thatincludesinsightfulgeologicalcharacterizationofthefinestructure
offaultzones, newlaboratoryexperimentsthatrevealresponsepropertiesinrapidorlargeslip,
andnewtheoreticalconceptsformodelingdynamicrupture.Thepurposehereistoreviewsome
ofthosenewperspectivesandtheirimpactonhowwethinkaboutearthquakerupturedynamics.
1.1 Faultzonestructure,frictionandaquandaryinseismology
Fieldobservationsofmaturelyslippedfaultsshowagenerallybroadzoneofdamagebycrackingand
granulation(Chesteretal.,1993),butneverthelesssuggestthatshearinindividualearthquakestakes
placewithextremelocalizationtoalong-persistentslipzone,<1–5mmwide,withinordirectly
borderingafinelygranulated,ultracataclasticfaultcore(ChesterandChester,1998;Chesteretal.,
2003,2004;Heermanceetal.,2003;WibberleyandShimamoto,2003).
Ontheotherhand,theshearstrengthalongafaultmayberepresentedby
τ =fσ where σ =σ −p (1)
n f
Heref isthefrictioncoefficient,σ istheeffectivenormalstress,σ isthetotalnormalstress
n
clampingthefaultshut,andp istheporepressurealongit.Itiswellknownthatlabestimatesoff
f
3
© 2010 by Taylor and Francis Group, LLC
4 JamesR.Rice,etal.
forrocks(underslidingratesof,say,μm/stomm/s)areusuallyhigh,f ∼0.60–0.85(e.g.,Byerlee
(1978)).
Giventhatfaultslipzonesseemtobesoextremelythin,onemustconcludethatifthosef prevail
duringseismicslip,withp thatismuchclosertohydrostaticthanlithostatic,weshouldfindthe
f
following: (a)measurableheatoutflownearmajorfaults, and(b)evidenceofextensivemelting
alongexhumedfaults.However,neithereffect(a)or(b)isgenerallyfound.
1.2 Weakfaults,vs.staticallystrongfaultsthatdynamicallyweaken
Therearetwogenerallinesofexplanationthathavebeenexploredtoresolvethisquandary.One
lineofexplanationsimplypostulatesthatmajorfaultsareweak.Thatcouldbebecausefaultcore
materialsaresimplydifferentfrommostrocksandhaveverylowf,e.g.,likedocumentedforsome
claysandtalc.Alternatively,itcouldbebecausef isnotnecessarilylow,butporepressurep is
f
highandnearlylithostaticovermuchofthefault,especiallydown-dipwhereσ islarge.
n
It is not the purpose here to argue against such weak-fault lines of explanation, but rather to
explore an alternative which we are led to by recent observations. That is that major faults are
staticallystrongbutdynamicallyweakenduringseismicslip.Owingtotheextremethinnessofslip
zones,therelevantfaultweakeningprocessesduringlargecrustaleventsarelikelytobethermal
and, given the damage zones and geologic evidence of water-rock interactions within them, it
seemsreasonabletoassumefluidpresence.Ofthevariousdynamicweakeningprocessesthusfar
identified,ithasbeenarguedthattwoshouldbesingledoutasbeingessentiallyuniversal,inthat
theyareexpectedtobeactiveandimportantfromthestartofseismicslipincrustalevents(Rice,
2006;RiceandCocco,2007).Theseareasfollows:
1. Flashheatingandhenceshearweakeningoffrictionalmicro-asperitycontacts,aprocesswhich
reducesf inrapidslip,and
2. Thermalpressurizationofporefluid,whichreducestheeffectivestress;p increases,because
f
thehighlygranulatedfaultgougeisoflowpermeabilityandthethermalexpansioncoefficient
ofwaterismuchgreaterthanthatoftherockparticles.
Other thermal weakening processes may set in at large enough slip or large enough rise in
temperatureT alongthefault.Theseincludethefollowing:
f
3. ThermaldecompositionatlargeriseinT inlithologiessuchascarbonates, thusliberatinga
f
fluidproductphaseathighporepressure,
4. Formationofagel-likelayeratlargeslipinwetsilica-richfaultzones,orsomerelatedprocess
relyingonthepresenceofsilicaandwater,and
5. Theultimatethermalweakeningmechanism,formationofamacroscopicmeltlayeralongthe
faultatlargeenoughslipandriseofT ,if theabovesethasnotlimitedtheactualincreaseof
f
T tolevelslowerthatthatforsuchbulkmelting.
f
While we focus on processes (1) and (2), it is very important to understand (3), (4), and (5)
and others not yet identified. Still, in a sense the latter are secondary, because one expects that
some significant earthquake slip, and fault weakening, will already have occurred before they
can become activated. Preliminary estimates (Rempel and Rice, 2006) of when (5) would set-
insuggestthatwithhydrostaticp andrepresentativematerialparameterranges, (1)and(2)are
f
sufficiently effective at shallow fault depths that slip in significant earthquakes could often be
accommodated without an onset of macroscopic melting, but that deeper in a fault zone, where
theinitialσ −p (whichscalestherateofheatinput), andtheinitialT , arehigher, meltonset
n f f
shouldoccurduringincreasingslipoftypicalsurface-breakingearthquakes.Forquantificationof
theslipsandparameterrangesinvolved,seeRempelandRice(2006).
Flashheating, weakeningprocess(1), isamechanismthathasbeenadvancedtoexplainhigh
speedfrictionalweakeninginmetals(BowdenandThomas,1954;Archard,1958/59;Ettles,1986;
LimandAshby, 1987; Limetal., 1989; Molinarietal., 1999). Itisonlyrelativelyrecentlythat
ithasbeenconsideredasaprocessactiveduringearthquakeslip(Rice, 1999, 2006; Beelerand
Tullis, 2003; Beeler et al., 2008; Tullis and Goldsby, 2003a,b; Hirose and Shimamoto, 2005;
© 2010 by Taylor and Francis Group, LLC
Thermo-andhydro-mechanicalprocessesalongfaultsduringrapidslip 5
Nodaetal.,2006;Noda,2008).Becauseoftherelativelylowthermalconductivityofmostrocks,
andtherelativelyhighshearstresseswhichtheysupportatfrictionalmicro-contacts, theyarein
fact susceptible to weakening by flash heating starting at sliding rates as low as 0.1 to 0.3 m/s,
which is well less than the average slip rate of ∼1 m/s (Heaton, 1991) inferred from seismic
inversions for large earthquakes. Thermal pressurization, process (2), has independent roots in
the literature on large landslides (Habib, 1967, 1975; Anderson, 1980; Voigt and Faust, 1982;
Vardoulakis, 2002; Veveakis et al., 2007; Goren and Aharonov, 2009) and that on earthquakes
(Sibson,1973;Lachenbruch,1980;MaseandSmith,1985,1987;LeeandDelaney,1987;Andrews,
2002;Wibberley,2002;NodaandShimamoto,2005;Sulemetal.,2005;Rice,2006;Rempeland
Rice,2006;GhabezlooandSulem,2008;Nodaetal.,2009).
Process(3),thermaldecompositionwithgenerationofahigh-pressurefluidphase(O’Haraetal.,
2006; Hanetal., 2007; SulemandFamin, 2009)is, ofcourse, atypeofthermalpressurization.
Inconsideringprocess(2),thefluidphaseispresumedtopre-existinporespaceswithinthefault
gouge so that the pressurization begins as soon as slip and consequent frictional heating begin,
whereasin(3)thefluidphasecomesintoexistenceonlyonceenoughslip,frictionalheating,and
temperaturerisehaveaccumulatedtoinitiatethedecomposition.Process(4)isbasedonfindings
fromexperimentsatlargebutsub-seismic(inresultsreportedthusfar)slipthat,inpresenceofwater,
frictionalweakeningatlargeslipisgreatestforrocksofgreatestsilicacontent(GoldsbyandTullis,
2002;DiToroetal.,2004;RoigSilvaetal.,2004).Theweakeningisarguedtobeduetoformation
ofaninitiallyweaksilica-gellayerthroughreactionofwaterwithfinesilicaparticlesfromfresh
comminutionalongtheshearzone. Therearemanystudiesofprocess(5), macroscopicmelting
infaultzones,ofwhichthelong-livedsignatureisnoncrystallinepseudotachylyteveinsalongthe
faultsurfaceandinside-wallinjections.RecentcontributionsincludeSpray(1995),Tsutsumiand
Shimamoto(1997),FialkoandKhazan(2004),HiroseandShimamoto(2005),Sironoetal.(2006),
andNielsenetal.(2008).
2 DYNAMICRUPTUREFORMULATION
2.1 Elastodynamicmethodology
Nodaetal. (2006, 2009)andDunhametal. (2008)havebeguntointegrateweakeningbyflash
heating and thermal pressurization into elastodynamic numerical methodology for spontaneous
rupture development. The problems thus far addressed are of rupture along a planar fault zone
within an effectively unbounded and homogeneous solid. For those, the implementation of an
elastodynamicboundaryintegralequation(BIE),withaspectralbasissetfortheslipandstress
distributions (Perrin et al., 1995; Geubelle and Rice, 1995) is extremely efficient and accurate.
Resultshavebeenobtainedfor2Danti-planeorin-planestrain.Intheformulation,withthexaxis
passingalongthefaultplane,theshearstressτ(x,t)alongthefaultandtheslipδ(x,t)arerelatedby
τ(x,t)=τ (x,t)−(μ/2c )V(x,t)+φ(x,t) (2)
0 s
whereV(x,t)≡∂δ(x,t)/∂tissliprate,μistheshearmodulus,c istheshearwavespeed,andthe
s
functionalφ(x,t)isgivenasalinearspace-timeconvolutionofanelastodynamickernel,dependent
onx−x(cid:4)andt−t(cid:4),withtheslipδ(x(cid:4),t(cid:4))forallx(cid:4),t(cid:4)withinthewaveconewithvertexatx,t.Here
τ (x,t)issomespecifiedloadingstressonthefault;itisthestressthatwouldhavebeeninduced
0
bytheappliedloadingsifthefaulthadbeenconstrainedagainstanyslip.Weprescribeτ (x,t)asa
0
uniformbackgroundstressτbforalltime,plussomelocalizedoverstressappliedatt =0tonucleate
rupture.δ(x,t)andφ(x,t)areexpandedinaFourierbasisset,sotheconvolutionisexpressedby
(cid:2) (cid:3) (cid:4)N/2 (cid:2) (cid:3) (cid:5)t
δ(x,t) = Dn(t) exp(inkˆx) with(cid:7) (t)= C (t−t(cid:4))D (t(cid:4))dt(cid:4) (3)
φ(x,t) (cid:7) (t) n n n
n
n=−N/2 0
© 2010 by Taylor and Francis Group, LLC