b'Education matters known lithological domains. Both theis found for zonal comparisons withbehaviours which suggest geological Mount Isa Fault and the Wonomo Faultsurface-wave anisotropy. We suggest thatinterference with anisotropic signare defined as steeply west dippingmore careful investigation of anisotropyJames Sweetman, Australian National structures with a protracted history ofbelow old seafloor is necessary in orderUniversity: Energetics of internal wavesearly normal movement and reverseto determine the presence of small-reactivation. The Rufus Fault wasscale convective patterns and layeredInternal waves are ubiquitous throughout interpreted as a steeply west-dippinganisotropy. the interior of stratified fluids. These structure with a protracted history ofwaves possess the unique quality of normal movement and reverse/dextralClaire Flashman, Australian Nationalanisotropic dispersion that enables for reactivation. A rose diagram structuralUniversity: Investigating seismicboth horizontal and vertical propagation. analysis was conducted on segmentsanisotropy across the Australian continentProminent in the global oceans, their of the Mount Isa, Rufus and Wonomothrough SKS splitting from the BILBY array generation is primarily caused by Faults and it was determined that thevertically disturbing isopycnals (surfaces Wonomo Fault Zone had more similarMost regions on Earth display apparentof constant fluid density) via bottom surrounding structural architectureanisotropy in the upper mantle, andflows interacting with topography. compared to that of the Rufus Faultsurface waves studies indicate thatInternal waves are of critical interest in Zone. This study recognised that theAustralia is no exception. Anisotropythe context of climate because they can Wonomo Fault is the likely southernhas been recorded down to 250 kmenhance deep-ocean mixing, thereby extension of the Mount Isa Fault duedepth beneath Australia, withinfluencing the Meridional Overturning them sharing: more similar surroundinganisotropic fast direction correlatedCirculation, the leading-order process by structural architecture, similar domainto Australias absolute plate motion.which the ocean impacts Earths climate bounding characteristics, protractedYet, previous shear wave splittingon centennial timescales.movement histories and the sameanalysis using SKS and SKKS waves have produced results which suggestIn this study, by way of idealised steeply west-dipping, north-southlaboratory experiments the energetics orientation. The Rufus Fault Zone isapparent isotropy potentially due to multiple layers of anisotropy beneathand dynamics of internal waves interpreted to be the same structuregenerated simultaneously from two as the Fountain Range Fault, linkedAustralia. There is however a lack of knowledge on how local geologydistinct topographic generation sites through a regional scale contractionalare investigated. This work extends strike-slip duplex and overprints theand frozen-in anisotropy contributes to lateral heterogeneities in seismicon previous work pertaining to the Mount Isa/Wonomo Fault Zones. energetics of internal waves generated anisotropy across the continent. This Leon Bilton, Australian Nationalthesis therefore further investigates thefrom a single topographic generation University: Oceanic anisotropy from PSstructures governing seismic anisotropysite. The primary focus here is splitting: Towards global models of upperbeneath Australia and attempts toexploratory, chiefly motivated towards mantle convection validate existing models of Australiandetermining which of the dimensionless anisotropy based on newer collectionsparameters that characterise internal Observations of seismic anisotropy (e.g.of seismic data. The present researchwave dynamics support conditions shear wave splitting) can provide directindicates that although local geologynecessary for the breaking of waves insights into the relationship betweencan impact anisotropy in local regions,through the non-linear interactions mantle convection in the Earths interiorthese results are consistent with twoof colliding wave beams and the and plate motions at the Earths surface.layers of anisotropy, with absolutesubsequent production of turbulence.Receiver based seismic observations overplate motion (APM)aligned flow in theThe experiments presented here oceanic plates are however currentlyasthenosphere and likely contributionspan a multi-dimensional parameter restricted due to the concentration offrom frozen-in anisotropy in thespace representing the geometry of seismic receivers on land. This projectcontinental lithosphere. We proposethe topography, and the tidal forcing suggests a method to overcome thisthat anisotropy beneath Australiafrequency and amplitude. The results limitation by utilising the distribution ofmaybe appropriately modelled using ainclude, (i) identifying that existing surface reflected seismic phases, suchtwo-layer model, with the lower layerlinear theory is applicable at low forcing as PS, which bounce once between thealigned with the APM and an upperamplitudes, and that (ii) some non-linear source and the receiver. From these in- layer orientated non-perpendicular toeffects may be represented by including formation is extracted about the seismicthis, possibly with a counter-clockwisean enhanced viscous dissipation, and anisotropy beneath oceanic bounce- rotation. Although the present work(iii) the identification of the parameter points, which is used to construct ancannot adequately constrain the fastregimes in which a recently discovered observational dataset of hundreds ofdirection for the upper layer in a two- non-linear wave interaction occurs.manually analysed shear-wave splittinglayer anisotropic model for Australia,Christopher Alfonso, University results with direct implications forthese results suggest that the previouslyof Sydney: The influence of dynamic mantle convective patterns beneathassumed perpendicular upper layertopography, climate, and tectonics on the oceanic plates. We observe bi-modal fastfor the two-layer anisotropic modelNile River source-to-sink systemdirections, however are unable to ruleshould be revisited. Local geology also out systematic errors. Delay times areappears to have a significant impact onAt a length of over 6000 km, the Nile comparable with previous shear-waveanisotropy; fast directions from splittingis the longest river in the world, and splitting studies (2 s). Results suggestresults in central Australia appear tohas long been of crucial importance to potential deviations of the anisotropiccorrelate well with gravity anomalieshuman civilisation in northern Africa, fabric from absolute plate motions,in the region, and regions in southernthanks both to the rivers fresh water and however more favourable agreementAustralia and near Mt Isa exhibitto the Nile Deltas hydrocarbon reserves. 37 PREVIEW DECEMBER 2020'