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TSUNAMI IMPACTS IN THE REPUBLIC OF SEYCHELLES, WESTERN INDIAN OCEAN

BY

ANNELISEB.HAGAN,1THOMASSPENCER,1DAVIDR.STODDART,2MAURICELOUSTAU-LALANNE,3andRONNYRENAUD3

ABSTRACT

TemporalandspatialcharacteristicsoftheDecember2004tsunamiintheRepublicofSeychelles,WesternIndianOceanaredescribed,withparticularreferencetothedetailedwaterlevelrecordfromthePointeLaRuetide-gauge,Mahé,andtsunamirun-upcharacteristicsonMahéandPraslin.AssessmentsoftsunamiimpactsoncoastalandshallowmarineenvironmentsinthegraniticislandsoftheNorthernSeychelles,andonthecoralislandsofselectedlocationsintheSouthernSeychelles,arereported.Thelackofnoticeableimpactswithinthesouthernislandscomparedtothosefurthernorthappearstoberelatedtobothreducedtsunamiwaveheightstothesouthandtodifferencesinregionalbathymetry,thetsunamibeingaccentuatedbytheshelfseasoftheSeychellesBankinthenorthandnotamplifiedaroundthesouthernislandssurroundedbydeepwater.

INTRODUCTION

Atsome5000kmfromSumatra,the115islandsoftheRepublicoftheSeychelleswerenotinthefrontlineoftsunamiimpacts.Onlytwotsunami-relatedfatalitieswerereported.Nevertheless,thetsunamididhaveaconsiderableinfrastructuralandeconomicimpact,notablyonthenortherngraniticislands.Therewasprolongedfloodingofthecapital,Victoria,asaresultoftheblockingofthestormdrainagesystembysedimentsmobilizedbythetsunami,fissuringandfailureofdockwallsatPortVictoriafromrepeatedinundationanddrawdowncyclesonunconsolidatedfills(Plates1,2),washoutsofkeytransportroutesbythedrainageoftsunamiwatersfromcoastallagoons(Plates3,4),disruptionstowatersupplyandseweragenetworks(withinthecaseofthelatterattendantpollutionproblems)andextensivestructuraldamagetohouses,hotels,restaurantsandotherbeach-frontinfrastructure.TotalestimatesofdamagehavebeenassessedatUS$30million(UNEP,2005)duetobothstructuraldamageandlossofearningsfollowingtheevent.Thetsunamiwassaidtohavedamaged94fishingboats,athirdoftheentirefishingfleet,aroundMahéandfishcatchesforJanuary2005dropped1CambridgeCoastalResearchUnit,DepartmentofGeography,UniversityofCambridge,DowningPlace,Cambridge,CB23EN,UK.2DepartmentofGeography,501McConeHall#4740,UniversityofCaliforniaBerkeley,CA94720,USA.3SeychellesIslandFoundation,POBox853,Victoria,Mahé,Seychelles.

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by30%comparedtopreviouscatchesforthismonth(Payet,2005,pers.comm.).HerewedocumentthetemporalandspatialcharacteristicsofthetsunamiintheSeychellesandreviewitsimpactongeomorphologyandshallowmarineecosystems.WedrawheavilyontheCanadianUnitedNationsEducational,ScientificandCulturalOrganization(UNESCO)missiontotheSeychelles(Jacksonetal.,2005)andontheInternationalUnionfortheConservationforNatureandNaturalResources(IUCN)report(OburaandAbdulla,2005),supplementedbyourownobservationsinMahé(StoddartandHagan,1and4/2005)andtheremotesouthernislandsoftheAmirantes,Alphonse/St.FrançoisandProvidenceBank(Hagan,1/2005),AldabraandAssumption(Stoddart4/2005).

CHARACTERISTICS OF THE 26 DECEMBER 2004 TSUNAMI IN THE SEYCHELLES

TemporalCharacteristics:GraniticIslandsoftheNorthernSeychelles

TsunamiwavesreachedtheSeychellesataboutthesametimetheyimpactedMauritiusandSalalah,Oman,ca.7hoursaftertheearthquake(Fig.2;Merrifieldetal.,2005).

Figure 1.IslandsoftheSeychelles,westernIndianOcean(afterStoddart,1970).

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Figure 2.WaterlevelrecordsforIndianOceanstations,showingthetimingandmagnitudeofthe26December,2004tsunami.Top-to-bottom:Salalah,Oman;PortLouis,Mauritius;PointeLaRue,Seychelles;Lamu,Kenya.(CourtesyofJ.Huthnance;availableathttp://www.pmel.noaa.gov/tsunami/indo20041226/tsunami2.pdf).

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Tsunamiamplitudesaregreatestperpendiculartogeneratingstructures;thustheNNW–SSEorientationoftheearthquakefaultlinebetweenNWSumatraandtheAndamanIslandsputtheSeychellesBankdirectlyinlinewiththetsunamiwavefrontasasimulationofwaveheights15hoursaftertheearthquakemakesclear(Fig.3;Yalcineretal.,2005).

Waveapproachwas,however,complicatedbythelarge-scalerefractionofthewavearoundsoutheasternSriLankaandsouthernIndiaandbysmaller-scalerefractioneffectsacrosstheMaldiveschainandtheChagosArchipelago(NOAA2005b)whichwerecrossedbythetsunamica.4hoursand2.5hoursearlier(Fig.4;Merrifieldetal.,2005).

AlllocationsintheIndianOceantothewestoftheearthquakeepicenterfirstexperiencedawavecrest(Merrifieldetal.,2005).ThisfirstarrivalwasseeninthetidegaugeatPointeLaRueonMahéat08:08–08:12CoordinatedUniversalTime(UTC)(12:08–12:12localtime)(Fig.5).Thelevelreachedwas0.59mabovemeansealeveldatum(MSLD)(Fig.6).Thefirstarrivalwasonarisingtide,thepredictedlowtidehavingbeenat07:26UTC(11:26localtime);waterlevelswereraisedbutonlytotypicalhighspringtidelevelsandnotashighastheprecedinghightide(whichhadpeakedat0.74mMSLD).Thefirstlargewavearrivedat09:12UTC(13:12localtime),registeringapeakof1.16mMSLD.Boththefirstarrivalandthefirstlargewavewerefollowedbysignificantdrawdowneventsof–1.53mMSLDat08:56and09:36–09:40respectively.However,theselevelsrelatetothebaseofthetide-gaugestillingwelland,therefore,mostprobablydonotrecordthecompletefallinwaterlevel.Fromeyewitnessreports,Jacksonetal.(2005)estimatethatthetruefallinwaterlevelmayhavebeenaslowas–4.0mbelowmeansealevel.Thereafterasequenceof8waveswasrecordedbythetide-gaugeincoupletsofalargerwaveofamagnitudesimilartothefirstarrivalfollowedbyasmallerwave;superimposedonarisingtidallevelthetrendwasforanincreaseintsunamiwaveheightpeakingat1.24mat12:52UTC(16.52localtime)(Fig.6).Thiswavewasfollowedbyafurthernoticeabledrawdowneventbutafterthenexthighwave,therewasalesseningofactivityafterca.14:30UTC(18:30localtime).

Figure 3.Computermodellingofthe26December,2004tsunamiafter900minutes(courtesyofA.Yalciner,U.Kuran,T.Taymaz)(availableat:http://yalciner.ce.metu.edu.tr/sumatra/max-elev-sim-1.jpg).

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Figure 4. Water-levelrecordsforIndianOceanstations,showingthetimingandmagnitudeofthe26December,2004tsunami.Top-to-bottom:Hanimaadoo,Maldives;Male,Maldives;Gan,Maldives;DiegoGarcia,BIOT.(CourtesyofJ.Huthnance;availableathttp://www.pmel.noaa.gov/tsunami/indo20041226/tsunami1.pdf).

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However,activitycontinuedintothenexthigh-tidecycle.Thepredictedhigh-tidelevel(peakstage=75cm)wasconsiderablyhigherthantheprevioushigh-tidelevel(12cm)andwhenthetsunamiactivitywassuperimposedonthishightideitresultedinawaterlevelof1.41mat00:56UTC(04:56localtime)on27December,almostexactly24hoursaftertheearthquakeand17hoursafterthefirstarrivalintheSeychelles(Figs.5and6).

EyewitnessaccountsoftsunamiimpactontheeastcoastofMahébroadlycorrespondtothetimingsextractedfromthetide-gaugerecord.However,thereareobservationsofsignificantdrawdowneventsat07:45–08:00and08:00UTC(11:45–12:00and12:00localtime)atAnseRoyale/AnseForbansandPointeauxSelrespectivelywhichappeartoleadthetide-gaugerecord(situated14kmtothenorthofAnseForbansand7kmnorthofPointeauxSel)byalmostonehour.However,thetimingsofthefirstlargewavearebroadlycomparabletothetide-gaugerecordatthesesites.AtAnsealaMouche,onthesouthwestcoast,drawdownagainappearstohaveoccurredpriortothatrecordedinthetide-gaugerecord.Thefirstlargewave,however,appearstohavebeenalaterimpactthanontheeastcoast,timedat09:25UTC(13:25localtime),presumablyreflectingtheslowingofthetsunamiwavefrontonrefractionaroundtheisland.Victoria,AnseRoyaleandAnseForbansontheeastcoastallexperiencedasecondphaseoffloodingbetween12:30and13:00UTC(16:30–17:00localtime),asdidAnsealaMoucheonthewestcoasthalfanhourlater,apatternconsistentwiththelaterarrivalofthefirstlargewaveearlierintheday.InVictoria,itisclearthattherewassignificantfurtherfloodingduringthenightof26–27Decemberclearlyassociatedwiththewavepeaktimedat01:00UTC(05:00localtime)(Jacksonetal.,2005).ThetsunamistruckPraslin,40kmtothenortheastofMahé,intwoseparatesurges,thefirstbeginningat08:10UTC(12:10localtime).ThiswasonehourbeforethefirstlargewavewasregisteredbytheMahétide-gauge.Therewasamajordrawdowneventbetweenthiswaveandthesecondlargerwavewhichoccurredat08:24(12:24localtime).Somelocationsregisteredlargewavesatca.09:30and10:00–11:00UTC(13:30and14.30–15:00localtime)andthelateafternoonwaveof26Decemberwasseenatthenorthwesternendoftheislandat12:45UTC(16:45localtime)(Jacksonetal.,2005).

ThePointeLaRuetide-gaugeshowedthatactivitycontinuedthroughout27December(Fig.5),withanenvelopeofresidualsaroundpredictedtidallevelsdecliningovera24-hourperiod(Fig.7).On28Decemberresidualswerestillpresentbutoftheorderof10cmorless;by30Decembertheeventwasover(Fig.7).

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Figure 5. Predicted tidal-curve and water-level records, Pointe La Rue tide-gauge, Mahé, Seychelles, 26–30 December 2004. Heights in cm relative to Mean Sea Level Datum. (National Meteorological Service Seychelles / University of Hawaii Sea Level Center; available at: http://ilikai.soest.hawaii.edu/uhslc/iotd/plar1.html).

Figure 6. Detail of Figure 5 showing predicted tidal level and individual tsunami peaks and water-level drawdowns, 26 December, 2004. (National Meteorological Service Seychelles / University of Hawaii Sea Level Center; available at: http://ilikai.soest.hawaii.edu/uhslc/iotd/plar5.gif).

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OneofthestrikingfeaturesofthetsunamiatanIndianOceanbasinscalewasthedifferentiationbetweenstations,associatedwithshelfareas,whichshowedasustainedtide-gaugesignaloverseveraldaysandthosestations,predominantlyinmid-oceanlocations,whichexhibitedastronginitialsignalbutlittlesubsequent“ringing”(Merrifieldetal.,2005).TheSeychellesclearlybelongedtothefirstcategory.TheimplicationisthatthetsunamiexcitedsomeformofseicheontheSeychellesBankthatbothamplifiedandprolongedthetsunamisignal;disentanglingthetwoeffectsremainsamajoranalyticalchallenge.

SpatialCharacteristics:GraniticIslandsoftheNorthernSeychelles

Statisticsontsunamiwaveheightsattheshoreline,tsunamirun-up(thetsunami’sheightabovemeansealevelatitslimitofpenetrationinland)andinundationdistancearereportedinTable1.Theyshowtheconsiderablesite-to-sitevariabilityoverdistancesoftenoflessthan10km.Thus,forexample,AnseBoileauonthewestcoastofMahérecordedarun-upof2.5mwhereasGrandeAnse5kmtothenorthexperiencedinundationto4.3m.Whileimpactsingeneralweregreatestoneasternshoresfacingthedirectionofwavearrival,thesignificanttsunamisignalspresentontheleewardcoastsofMahéandPraslinarenoteworthyandsuggesttheoperationofaseriesofcontrolsatanumberofdifferentspatialscales.

Figure 7.Waterlevelresiduals,PointeLaRuetide-gauge,Mahé,Seychelles,26–30December,2004.(NationalMeteorologicalServiceSeychelles/UniversityofHawaiiSeaLevelCenter;availableat:http://ilikai.soest.hawaii.edu/uhslc/iotd/plarbr.html).

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Atthelargestscale,ocean-basinscalemodellingoftheDecemberevent(e.g.,NOAA,2005b)showsdivergenceofthetsunamiaroundtheshallowshelfareasoftheMascarenePlateau,thestreamingofthewave-frontaroundbankmarginsandtheconvergenceofthewaveintheleeofthePlateauatseverallocations,includingontheSeychellesBank(NOAA,2005b).RefractionattheBankscaleissupportedbytheobservationfromthenorthwestpointofPraslinthatthewavecamefromthenortheast(Jacksonetal.,2005).ItcanbeimaginedthatontheSeychellesBanktherewerefurtherrefractioneffectsaroundthelargerindividualislands.Thus,forexample,eyewitnessaccountsoftsunamiwavearrivalatAnsealaMoucheontheleewardsouthwestcoastofMahéreportedthatwavetrainsapproachedthebayfromboththenorthandsouth(Jacksonetal.,2005).Similarly,maximumwaveheightsonPraslinwereexperiencedontheleeshore(Table1).

Table 1. Maximum water levels at the coast and wave run-up, relative to mean sea level, of the 26 December, 2004 tsunami in the Seychelles (from Jackson et al., 2005).

Location Maximum Water Level Near Shoreline

(m)

WaveRun-up

(m)

InundationDistance (m)

North East Point Mahé 2.2 100 Victoria Mahé >1.7 >1.4 >200 SeychellesInternational Airport

Mahé3.0 200

Anse aux Pins Mahé >1.9 >50 Pointe au Sel Mahé 2.8 2.3 >35 Anse Royale (N) Mahé >3.8 3 >100 Anse Royale (S) Mahé >4.4 >45 Anse Forbans Mahé 2.8 20 Baie Lazare Mahé 1.6 20 Anse a la Mouche Mahé 3.0 (3.5)* 2.5 250 Anse Boileau Mahé 2.5 53 Grand Anse Mahé 4.3 nil Beau Vallon Mahé 1.7 10 Chevalier Bay Praslin 3.1 140 Anse Possession Praslin 3.0 35 Anse Petit Cour Praslin 2.5 225 Anse Volbert (1) Praslin 1.9 100 Anse Volbert (2) Praslin 2.0 >100 Grande Anse Praslin 3.6 >50 Baie Ste Anne Praslin 1.8 nil

*Figureof3.5matAnsealaMoucherecordsheightofwavesurgedamage.

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Withintheseisland-widepatternsofincidence,tsunamiimpactsweresensitivetochangesinshorelineorientation.Thus,forexample,atBeauVallon,Mahé,whichfacesnorth,themaximumrun-uplevelwasonly1.7m,slightlyaboveanormalhigh-tide.Similarly,thesoutheast-facingBaieSteAnneonPraslinonlysufferedinundationtotypicalhigh-tidelevel(Jacksonetal.,2005).Inaddition,waveswerefunnelledbetweenrockyheadlandsintoembaymentsandinfluencedbyoffshorefringingreeftopography,particularlythepresenceorabsenceofdeep-waterpassagesthroughthereefsystem.Inreef-frontedlocationsitappearsthatthetsunamiwavesbrokeonthereefandthenpropagatedacrossthereefasabore.Thesewaterflowswereinfluencedbywaveinteractions(includingwaverefractionandreflection)andinteractionswithbottomtopography.Inparticular,itappearsthattsunamirun-upwasoftengreatestattheheadofdeepchannelsthroughfringingreefs.Finally,attheverylocallevelitisclearthattouristdevelopmentverycloseto,orevenon,thebeachmademanybuildingshighlyvulnerabletowaterlevelsevenonlyslightlyabovenormalhigh-tidelevelsandtosurgevelocitiesof3.3–4.4ms-1,particularlywherethenaturalenergydissipationaffordedbythepresenceofupperbeachbermsand/orcoastalvegetationhadbeenremovedtoenhancebeachaccess(Jacksonetal.,2005).

ImpactsontheMarineEnvironment:GraniticIslandsoftheNorthernSeychelles

Aseriesofrapidassessmentsofmarineenvironmentsinthegraniticislandsbetween30December,2004and13February,2005(OburaandAbdulla,2005)identifiedtwomajorpatternsofcoral-reefdamagerelatedtolocationandsubstratetype.ThemostheavilyimpactedareaswerecarbonatereefsubstratesinthenorthernislandsaroundPraslin(includingCurieuse,LaDigue,Felicite,IsleCocoandSte.Pierre).Herelevelsofsubstratedamage(movementofrubble,erosiongullieswithinrubbledeposits)exceeded50%,andlevelsofdirectcoraldamage(coraltopplingandoverturning)exceeded25%.Bycomparison,aroundMahédamagelevelsoncarbonatesubstrateswerelessthan10%.ThroughoutthegraniticislandsoftheSeychelles,levelsofdamageongraniticsubstrateswerelessthan1%(OburaandAbdulla,2005).Cementedreefsubstratesshowedlittleevidenceofcoralbreakageoroverturning;wheredamagewaspresentitwasrestrictedtowaterdepthsoflessthan50cm.However,manyreefsurfacesinthegraniticSeychellesarecurrentlycharacterizedbypoorlyconsolidatedsurfacesresultingfromreef-frameworkdegradation,followingthecoral-bleachingandmass-mortalityeventassociatedwiththeIndianOceanwarmingof1998(e.g.,Spenceretal.,2000).Therewasconsiderablemovementofreefrubbleinsuchsettingsundertsunamisurgeconditions,andthedislocationanddamageoflivecoralcoloniesestablishedonsuchsurfaces(OburaandAbdulla,2005).

ItisimportanttorealisethatasubstantialsectoroftheeastcoastreefshasbeenprofoundlymodifiedsincetheclassicaldescriptionsofthembyLewis(1968,1969),Taylor(1968)andthesummariesbyBraithwaite(1984)andStoddart(1984).Startingwiththeconstructionoftheairstripin1971,large-scalereclamationnowextendsfor11kmfromnorthofVictoriatoPointeLaRue.Thereclamation,usedforhousing,light

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industry,andrapidroadaccesstotheairport,typicallyisseparatedfromtheoldislandshorelinebyopenwater.Surgesinsea-levelcanthusbepondedbehindthemandcanonlydrainbacktoseaviaegresschannels.ThisaccountsforthedestructionofthebridgeshowninPlate3.Drawdownandupsurgewerealsoseverelydampedintheleeofthereclamations.

Thetsunamiresultedinbeachcliffingof2.5matAnseKerlan,northwestPraslinandacalculatedlossof200x103m3ofbeachsandoffshore(UNEP,2005).Thewavesalsomobilizedmarinesediments,bothstrippingsedimentsfromcoral-reefrubblebedsanddepositingsedimentsinnewlocations;back-drainagefromrun-upmayhavealsodepositedterrestrialsedimentsonfringingreefs.Theseprocesseswereexacerbatedbystormyweatherinthedaysimmediatelyfollowingthetsunamiwhichgeneratedroughseas.Rainfalltotalsinexcessof250mmtriggeredlandslidesonMahéandledtohighterrestrialrunoffbutitisnotcleariffluvialsedimentsreachedreefenvironments.Fringingreefswereexposedbythesignificantdrawdownevents(e.g.,reportedforAnseRoyale,AnseForbansandAnsealaMouche,Mahé;exposureofmassivecoralsatAnsePetitCour,Praslinat08:00UTC,26December;Jacksonetal.,2005)butitisunlikelythattheseeventswereofsufficientdurationtocausecoraldeath.SeagrassesatBaieTernai,Maheweresmotheredbycarbonatesedimentsbutgeneraldamagelevelsinseagrassbedswerelow.ThecausewayenclosingthemangroveparklandatCurieusewastoppledinwardsbytsunamiwavesbutnodamagetothemangroveswasnoted(OburaandAbdulla,2005).

TsunamiImpactsintheSouthernSeychelles

AcollaborativeexpeditionbetweentheKhaledbinSultanLivingOceansFoundation,CambridgeCoastalResearchUnitandSCMRT-MPAtothesouthernSeychelleswasconductedonboardM.Y.GoldenShadow,10–28January2005.Althoughtheprimaryfocusofthisexpeditionwasairbornemappingoftheouterislands,duetothetimelynatureofthisexpedition,itwasexpectedthatimpactsofthetsunamiontheremotesouthernislandsoftheSeychellescouldalsobereported.TheexpeditionvisitedtheislandsofProvidence,St.Pierre,AlphonseandSt.FrançoisandthesouthernislandsoftheAmirantesgroup(D’Arros,Desroches,Desnoeufs,Marie-Louise,Boudeuse,EtoileandPoivre)somepreviouslydescribedbyStoddart(1970).StoddartalsovisitedAldabraandAssumptioninApril2005.

OnallthesouthernSeychellesislandsvisitednophysicaldamagetoeithertheterrestrialormarineenvironmentswasobserved.Thelittoralhedgewasintactinallcasesandtherewasnoevidenceofbeachsedimentmovementorwaterinundationinthelittoralarea.Underwatertherewasnoevidenceofreefdamage;thus,forexample,therewasnophysicaldamagetothebranchingcorals(principallyPocilloporaspp.)thatdominatethesereefsandnocoraltoppling.TheislandsofProvidence,Alphonse,D’Arros,Desroches,Marie-LouiseandPoivreareinhabited.Inallcases,islandpersonnelsaidthattherehadnotbeenanyimpactcausedbythetsunamiandtheyhardlynoticedtheevent.OnProvidenceIsland,theislandmanagerwasradioedfromMahéandwarnedofthetsunamiwavesapproaching.TheI.D.C.(IslandDevelopmentCompany)manager

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onAssumptionandthemanageroftheS.I.F.(SeychellesIslandFoundation)ResearchStationonAldabrabothstatethatinspiteofradiowarningstheydidnotdetectanytsunamisurges.Itisfairtoaddthatiftherehadbeenasubstantialsurgeitwouldhaveimpactedrockycoastlinesintheeastofeachisland,andthatinbothcasesthesettlementsareinprotectedwesternlocations.ProvidenceIslandisatthenortherntipofthelarge(approximately400km2)ProvidenceBank,andherethetsunamiwasobservedasasuddeninfluxofwaterapproximately10cmhigherthannormalthatremainedforafewminutesbeforedroppingtoanormallevel.Noaccuratetimecouldbegivenforthisobservation,butitwassaidtobe“aboutlunch-time”.UnfortunatelytherearenoreportsoftsunamieffectsonCoetivy.

ComputermodellingofthepassageofthetsunamiwavefrontindicatesaregionalscalerefractionofthewavefronttowardsthesouthwesternIndianOcean(NOAA,2005b).Thiswouldhaveledtoanincreaseinthelengthofwavecrestandhencelowerwaveheightstothesouth.Inaddition,thereareconsiderablecontrastsinbathymetricsettingbetweenthetwoareas.Incontrasttothenorthern,graniticislandsoftheSeychelles,thesouthernislandsaretypicallylow-lyingsandcays(islandsoftheAmirantes)andatolls(Alphonse,St.François;Desrochesisadrownedatoll)withtheexceptionofSt.Pierrewhichisaraisedplatformreefisland.ThegraniticislandsprotrudefromtheshallowSeychellesBank(meanwater-depth44-65m;Braithwaite,1984),butthesouthernislandsaresituatedinopenoceanandexhibitsteeplyshelvingfore-reefslopesorverticalreefwalldrop-offs,surroundedbydeepwater(>5,000m).Thuswhenthetsunamiapproachedtheregionofthesouthernislands,thewavespassedthroughthegapsbetweentheislandsandtherewasnoincreaseinwaveamplitudeduetothecontinuityofdeepwaterandlackofashallowbarrierintheflowpath.ThiswouldexplainthecontrastbetweenthelackoftsunamiimpactsobservedonthesouthernSeychellesislandscomparedtothesignificantimpactsobservedonthegraniticislandsoftheSeychellesBank.

ACKNOWLEDGEMENTS

ObservationsintheRepublicofSeychellesweresupportedthroughacollaborativeexpeditionbetweentheKhaledbinSultanLivingOceansFoundation,CambridgeCoastalResearchUnit,UniversityofCambridgeandSeychellesCentreforMarineResearchandTechnology–MarineParksAuthority(SCMRT–MPA).FieldworkinthesouthernSeychelleswasconductedonboardtheKhaledbinSultanLivingOceansFoundationvessel,theM.Y.GoldenShadow,10–28January2005.WearegratefultoCapt.P.Renaud,ExecutiveDirector,KhaledbinSultanLivingOceansFoundationforextensivelogisticalsupportandtotheSeychellesIslandDevelopmentCompanyforpermissiontovisitislandsintheSouthernSeychelles.

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te 1

Plate 1 Plate 2

Plate1.Internalfissuringandcollapseofdockquay,PortVictoria,Mahé.

Plate2.Failureofquayside,PortVictoria,Mahé.

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Plate 3. Road bridge washout from seaward drainage of tsunami waters from coastal lagoon, west coast of Mahé.

Plate 4. Road bridge washout following drainage of tsunami waters, southwest Mahé.