multistep modelling of receiver based seismic and ambient noise data from wombat array crustal structure beneath southeast australia summary a limitation of most forms of passive seismic tomography using distant earthquakes lies in the fact that crustal structure is poorly resolved an attempt is made here to address this issue by modelling teleseismic receiver functions rfs and dispersion curves derived from ambient noise through a multistep approach the seal3 experiment in central and southern new south wales nsw used here represents one of 13 array deployments that so far comprise the large wombat project which aims to cover a significant portion of the australian continent with a rolling array of seismometers an interactive forward modelling software package irffm2 is introduced and applied to the observed rfs and surface wave dispersion curves to define a prior physically acceptable range of elastic parameters in the lithosphere which is combined with a grid search and a linearized inversion our results emphasize the importance of a joint treatment of rfs and dispersion data as the predictions from 1 d velocity models at individual stations derived from only rfs display large departures from the observed ambient noise dispersion curves in total 27 jointly constrained 1 d shear wave models are produced which provide sufficient sampling of the crust beneath seal3 to permit detailed inferences about lateral variations in structure to be made of particular note is the observation that the moho deepens towards the mountainous southeast where it exceeds 50 km in depth beneath the southern highlands of nsw thus marking out some of the thickest crust in australia the complex lateral variations in mid lower crustal velocity that we observe probably reflect the manifold interactions of a thinning lithosphere associated igneous underplating recent hot spot related volcanism and uplift our results image an important part of the lithosphere that is poorly constrained by regional and teleseismic tomography and contribute to the understanding of the formation of the southern highlands and the palaeozoic lachlan orogen

crustal structure of the east gondwana margin in southeast australia revealed by transdimensional ambient seismic noise tomography 1 ambient seismic noise data from the ongoing wombat transportable seismic array in southeast australia the largest deployment of its kind in the southern hemisphere are used to produce a high resolution 3 d shear wave velocity model of the region we apply a two stage transdimensional hierarchical bayesian inversion approach to recover phase velocity maps at periods of 1 20 s and then invert phase velocity dispersion for 3 d shear wave velocity structure to the base of the crust data uncertainty is propagated through the sequence of inversions ensuring that model complexity is justified by the quality and quantity of the measurements the pattern of 3 d velocity variations helps elucidate the geometry and position of key crustal features such as the torrens hinge zone associated with the transition from paleozoic eastern australia to precambrian central and western australia that formed along the proto pacific margin of east gondwana

dynamic processes acting on a longitudinal seif sand dune abstract field measurements were made on a longitudinal dune in the sinai desert in order to understand its morphology and dynamics the field measurements contradicted the wind structure indicated by the helicoidal flow theory rather it was found that winds coming from two basically different directions at different times and striking the dune obliquely were responsible for sand transport and erosion or deposition along the lee flank the essence of this mechanism is the deflection of the wind airflow on the lee flank of the dune to a direction parallel to the crest line the occurrence of erosion or deposition depends upon the angle of incidence between the wind and the crest line when this angle is 40 the velocity of the deflected wind drops and deposition takes place on the lee flank the angle of incidence in each wind storm is changed intermittently between 30 and 100 along the dune because the dune meanders and because of the sinuous outline of the crest line in this manner sand transport and erosion or deposition occurs along the lee flank depending on the angle of incidence between the wind and the crest line as a result of the deflection of the wind the dune elongates at an average rate of more than 1 m per month peaks and saddles along the crest line advance at an average rate of 0 7 m per month the lack of uniformity in the effects of the wind on both sides of the dune creates a lack of uniformity in the rate of erosion and deposition this can explain the formation of peaks along the crest line of the dune

seismic interferometry turning noise into signal turning noise into useful data every geophysicist s dream and now it seems possible the field of seismic interferometry has at its foundation a shift in the way we think about the parts of the signal that are currently filtered out of most analyses complicated seismic codas the multiply scattered parts of seismic waveforms and background noise whatever is recorded when no identifiable active source is emitting and which is superimposed on all recorded data those parts of seismograms consist of waves that reflect and refract around exactly the same subsurface heterogeneities as waves excited by active sources the key to the rapid emergence of this field of research is our new understanding of how to unravel that subsurface information from these relatively complex looking waveforms and the answer turned out to be rather simple this article explains the operation of seismic interferometry and provides a few examples of its application

group velocity tomography of the upper crust in the eastern tennessee seismic zone from ambient noise data abstract the eastern tennessee seismic zone etsz is the second most seismically active area in the central and eastern united states after the new madrid seismic zone but the relatively weak seismicity and the absence of correlation between the seismicity distribution and the surface geology make its seismogenic potential controversial in this work we investigate the structure of the upper crust in the etsz by means of group velocity tomography maps from seismic noise data results show that the seismic activity is associated with a relatively low velocity anomaly mainly located in one or more basement blocks these blocks bounded to the nw by the ny al lineament and to the se by the clingman lineaments are buried beneath low velocity strata consistent with the presence of a relatively thick sedimentary cover the imaged low velocity anomaly migrates towards the se at increasing periods suggesting a possible se dipping weak structure where most of the seismic activity takes place the correlation between the ny al magnetic signature and the position of the seismic velocity anomalies supports the interpretation of the low velocity zone as a major basement fault projected to the surface as the ny al magnetic lineaments the fault juxtaposes granite rhyolite basement to the nw with grenville southern appalachian basement to the se

a sheetflow sediment transport model for skewed asymmetric waves combined with strong opposite currents abstract prototype scale physical model tests were conducted to investigate the sheetflow sediment transport of uniform sand under different skewed asymmetric oscillatory flows with and without the presence of relatively strong currents in the opposite direction against wave propagation experiments show that in most cases with fine sands the cancelling effect which balances the on off shore net transport under pure asymmetric skewed oscillatory flows and results a moderate net transport was developed for combined skewed asymmetric shaped oscillations however under certain conditions t 5 s with coarse sands the onshore sediment transport was enhanced for combined skewed asymmetric flows additionally the new experimental data under collinear oscillatory flows and strong currents show that offshore net transport rates increase with decreasing velocity skewness and acceleration skewness sediment movement behaviors were investigated through analysis of experimental data obtained from the image analysis technique and attempts were made to estimate and formulate the sheetflow layer thickness accordingly sediment transport under oscillatory sheetflow conditions was studied and successfully explained by comparing the bed shear stress and the phase lag parameter at each half cycle consequently these parameters were incorporated in an improved dibajinia and watanabe s type sediment transport model the formula is calibrated against a comprehensive experimental data 331 in total good agreement obtained between predictions and measurements shows that the new formula is fulfilled for practical purposes

efficient regional scale 3d potential field geophysical modelling to redefine the geometry of granite bodies beneath prospective geologically complex northwest tasmania in this study a regional model that defines the three dimensional geometry of the subsurface geology beneath the complex prospective northwestern tasmania has been developed this has been achieved using a series of potential field inversions constrained by surface geology geological sections seismic interpretations and a newly extended petrophysical dataset three major episodes of granitic magmatism are preserved in tasmania in the neoproterozoic cambrian and devonian granite bodies are hence considered important indicators of mineralization for explorers in an area of challenging vegetation topography and cover sequences forward modelling and property based inversions of the pre existing geological model show that the previously interpreted subsurface geometry is not compatible with potential field data four sub regions displayed a large discrepancy between calculated and observed data this study redefines the subsurface geometries of these sub regions through individual geometry inversions the density and magnetic susceptibility ranges of units are further refined through property inversions the modified geometry of the devonian granites in the four sub regions may be summarized as follows 1 the housetop granite is relatively thin 5 km thickness whereas 2 the heemskirk and meredith granites are very thick and granite extends to a shallower depth between these bodies than previously interpreted this region between plutons is thus a more prospective region than previously thought 3 for the first time an intrusive body underlying the eastern part of the rocky cape group has been identified its petrophysical properties are similar to that of a granite and its top is interpreted at a depth of 3 km this interpreted low density granitic unit may be either neoproterozoic or devonian 4 a new non magnetic low density cambrian granite with a minimum burial depth of 1 km is also modelled in 3d within the mount read volcanics in the south of the study area our approach whereby sub regions are identified for more detailed modelling enables new constraints to be introduced in a computationally efficient way and has general application to refining the geometry of key structures in prospective regions

new insight into cainozoic sedimentary basins and palaeozoic suture zones in southeast australia from ambient noise surface wave tomography 1 detailed images of rayleigh wave group velocity are derived from ambient seismic noise recorded by wombat a large rolling seismic array project in southeast australia group velocity maps sensitive to crustal structure exhibit low velocity anomalies in the presence of sedimentary basins and recent hot spot volcanism and high velocities in regions of out cropping metamorphic and igneous rocks distinct and well constrained patches of low velocity within the murray basin provide new insight into the spatial extent and possible composition of pre tertiary infra basins in a broader tectonic context our results show little evidence for the palaeozoic building blocks of the southeast australian continent that have been inferred from geological mapping and potential field data this may mean that apparent changes in basement terrane near the surface are not associated with major changes in composition at depth

surface wave array tomography in se tibet from ambient seismic noise and two station analysis i phase velocity maps summary empirical green s functions egfs between pairs of seismographs can be estimated from the time derivative of the long time cross correlation of ambient seismic noise these egfs reveal velocity dispersion at relatively short periods which can be used to resolve structures in the crust and uppermost mantle better than with traditional surface wave tomography we combine rayleigh wave dispersion estimates from egfs and from traditional two station ts analysis into a new approach to surface wave array tomography with data from dense receiver arrays we illustrate the methodology with continuous broad band recordings from a temporary seismographic network on the southeastern part of the tibetan plateau in sichuan and yunnan provinces sw china the egfs are robust under temporal changes in regional seismicity and the use of either ambient noise approximated by records without signal from events with magnitude mb 5 or 4 or surface wave coda produces similar results the egfs do not strongly depend on the presence of large earthquakes but they are not reciprocal for stations aligned in the n s direction this directionality reflects the paucity of seismicity to the north of the array using a far field representation of the surface wave green s function and an image transformation technique we infer from the egfs the rayleigh wave phase velocity dispersion in the period band from 10 30 s a classical ts approach is used to determine rayleigh wave phase velocity dispersion between 20 120 s together they constrain phase velocity variations for t 10 120 s which can be used to study the structure from the crust to the upper mantle beneath se tibet short and intermediate period 10 80 s phase velocities are prominently low suggesting that the crust and upper mantle beneath se tibet is characterized by slow shear wave propagation

automated detection extraction and measurement of regional surface waves our goal is to develop and test an effective method to detect identify extract and quantify surface wave signals for weak events observed at regional stations we describe an automated surface wave detector and extractor designed to work on weak surface wave signals across eurasia at intermediate periods 8 s 40 s the method is based on phase matched filters defined by the rayleigh wave group travel time predictions from the broadband group velocity maps presented by ritzwoller and levshin 1998 and ritzwoller et al 1998 and proceeds in three steps signal compression signal extraction or cleaning and measurement first the dispersed surface wave signals are compressed in time by applying an anti dispersion or phase matched filter defined from the group velocity maps we refer to this as the compressed signal second the surface wave is then extracted by filtering noise temporally isolated from the time compressed signal this filtered signal is then redispersed by applying the inverse of the phase matched filter finally we adaptively estimate spectral amplitude as well as group and phase velocity on the filtered signal the method is naturally used as a detector by allowing origin time to slide along the time axis we describe preliminary results of the application of this method to a set of nuclear explosions and earthquakes that occurred on or near the chinese lop nor test site from 1992 through 1996 and one explosion on the indian rajasthan test site that occurred in may of 1998

fossil seaward dipping reflector sequences preserved in southeastern australia a 600 ma volcanic passive margin in eastern gondwanaland evidence for a c 600 ma rifted passive margin in eastern australia exists in the form of multiple belts of mafic volcanic rocks preserved along the western margin of the tasman fold belt system and giving rise to elongate magnetic anomalies outcrop drillhole and geophysical evidence points to piles of lavas volcaniclastic and intrusive rocks up to 6 km thick extending for strike lengths of hundreds of kilometres in individual segments the distinctive unifying characteristics of these piles are apparent common formation ages 600 580 ma presence of early more landward transitional alkaline basalts and more seaward abundant rift tholeiites with high temperature picrites and olivine rich basalts at most localities despite later structural reorganization these belts have close geochemical geometric and lithological affinities with mesozoic seaward dipping reflector sequences along the north atlantic and northwestern australian volcanic passive margins and strongly imply the formation of a volcanic passive margin in eastern gondwanaland at the close of the neoproterozoic recognition of this event has implications for the position of an implied earlier rifted margin related to the break up of rodinia around 780 ma a rifting event at 600 ma in eastern gondwanaland helps explain both the lack of evidence for volcanism from rodinia break up and a widespread 600 ma population of inherited zircons within rocks of the lachlan orogen which developed outboard of the passive margin in earliest palaeozoic time

transdimensional inversion of ambient seismic noise for 3d shear velocity structure of the tasmanian crust abstractambient seismic noise tomography has proven to be a valuable tool for imaging 3d crustal shear velocity using surface waves however conventional two stage inversion schemes are severely limited in their ability to properly quantify solution uncertainty and account for inhomogeneous data coverage in response to these challenges we developed a two stage hierarchical transdimensional bayesian scheme for inverting surface wave dispersion information for a 3d shear velocity structure and apply it to ambient seismic noise data recorded in tasmania southeast australia the key advantages of our bayesian approach are that the number and distribution of model parameters are implicitly controlled by the data and that the standard deviation of the data noise is treated as an unknown in the inversion furthermore the use of bayesian inference which combines prior model information and observed data to quantify the a posteriori probability distribution means that model uncertainty information can b

broadband ambient noise surface wave tomography across the united states 1 this study presents surface wave dispersion maps across the contiguous united states determined using seismic ambient noise two years of ambient noise data are used from march 2003 through february 2005 observed at 203 broadband seismic stations in the us southern canada and northern mexico cross correlations are computed between all station pairs to produce empirical green functions at most azimuths across the us coherent rayleigh wave signals exist in the empirical green functions implying that ambient noise in the frequency band of this study 5 100 s period is sufficiently isotropically distributed in azimuth to yield largely unbiased dispersion measurements rayleigh and love wave group and phase velocity curves are measured together with associated uncertainties determined from the temporal variability of the measurements a sufficient number of measurements 2000 is obtained between 8 and 25 s period for love waves and 8 and 70 s period for rayleigh waves to produce tomographic dispersion maps both phase and group velocity maps are presented in these period bands resolution is estimated to be better than 100 km across much of the us from 8 40 s period for rayleigh waves and 8 20 s period for love waves which is unprecedented in a study at this spatial scale at longer and shorter periods resolution degrades as the number of coherent signals diminishes the dispersion maps agree well with each other and with known geological and tectonic features and in addition provide new information about structures in the crust and uppermost mantle beneath much of the us

extensive seismic anisotropy in the lower crust of archean metamorphic terrain south india inferred from ambient noise tomography abstract we use rayleigh and love wave empirical green s function egf recovered from the cross correlation of seismic ambient noise to study the spatial distribution of radial anisotropy in the southern india crust the corresponding dispersion curves in the period 2 to 32 s are measured from ambient noise data recorded at 57 sites and the strength of anisotropy computed from the discrepancy between shear velocities obtained from rayleigh v sv and love v sh at various depths down to 40 km in upper crust up to a depth of 20 km the region is characterized by anisotropy coefficients of 2 to 2 that could be explained due to a combination of fluid filled open cracks and foliated metamorphic rocks at deeper levels beyond 20 km except for the archean metamorphic terrain most part of south india has anisotropies of up to 5 this may be due to rocks with varying degree of metamorphism beneath the archean metamorphic terrain the anisotropy is recorded up to 9 in the depth range of 20 40 km this high anisotropy is unlikely to be the manifestation of any recent geodynamic process considering that the region has low surface heat flow 30 mw m 2 we propose that the observed strong anisotropy in the metamorphic belt of southern india crust could best be explained as due to the presence of micaceous minerals or amphiboles in the deep crust that are formed possibly during the evolution of granulite terrain at 2 5 ga

uppermost mantle structure of the australian continent from pn traveltime tomography past studies of the seismic structure of the australian continent have dominantly exploited surface wave tomography for the mantle with seismic refraction receiver functions and ambient noise used for crustal structure the 3 d structure has been summarized in the australian seismological reference model ausrem for which the zone immediately below the crust is the least well characterized pn traveltime tomography provides a way of improving structural information on the uppermost mantle across the continent we have exploited waveforms from larger events across australia recorded at both permanent and portable stations since 1993 supplemented by bulletin arrival times to compensate for the large velocity contrasts with much faster mantle wave speeds in the center and west all events were relocated using the ausrem model after relocation consistent patterns of traveltime residuals are obtained we extract pn as the first arrival in the distance range 1 8 to 15 we use the fmtomo approach to invert the travel time residuals to generate a p wave speed structure with a resolution of 3 3 there is strong heterogeneity in pn wave speed in the uppermost mantle across the continent the fastest pn wave speed of 8 36 km s beneath the precambrian cratons of western and central australia is 3 99 faster than the global ak135 model and the slowest pn wave speed 7 66 km s on the eastern margin is 4 74 slower the slowest velocities in the uppermost mantle are found along the eastern margin of the australian continent beneath the phanerozoic orogenic belts with links to neogene volcanism

the structure of the upper mantle beneath the delamerian and lachlan orogens from simultaneous inversion of multiple teleseismic datasets abstract distant earthquake data recorded by seven sub arrays of the ongoing wombat rolling seismic array deployment in southeast australia are combined for the first time to constrain 3 d variations in upper mantle p wavespeed via teleseismic tomography the seven arrays comprise a total of 276 short period recorders spaced at intervals of approximately 50 km thus allowing unprecedented resolution of the upper mantle over a large region in the mantle lithosphere immediately below the crust 50 km depth dominant variations in velocity tend to strike east west and share little resemblance to palaeozoic boundaries in the shallow crust inferred from surface geology and potential field data a broad region of elevated wavespeed beneath northern victoria may represent the signature of underplated igneous rocks associated with detachment faulting during the break up of australia and antarctica a distinct low velocity anomaly in southern victoria appears to correlate well with the quaternary newer volcanic provinces towards the base of the mantle lithosphere the dominant structural trend becomes north south and five distinct velocity zones become apparent of particular note is a transition from higher wavespeed in the west to lower wavespeed in the east beneath the stawell zone implying that the proterozoic lithosphere of the delamerian orogen protrudes eastward beneath the western subprovince of the lachlan orogen this transition zone extends northwards from southern victoria into central new south wales the northward limit of the arrays and is one of the dominant features of the model further east there is a transition from lower to higher wavespeeds in the vicinity of the boundary between the western and central subprovinces of the lachlan orogen which has several plausible explanations including the existence of a proterozoic continental fragment beneath the wagga omeo zone the presence of elevated wavespeeds beneath the melbourne zone in victoria although not well constrained due to limited data coverage provides some support to the selwyn block model which proposes a northward extension beneath bass strait of the proterozoic core of tasmania

structure of magma reservoirs beneath merapi and surrounding volcanic centers of central java modeled from ambient noise tomography we present a three dimensional model of the distribution of s wave velocity in the upper crust to a depth of 20 km beneath central java based on the analysis of seismic ambient noise data recorded by more than 100 seismic stations in 2004 associated with the meramex project to invert the rayleigh wave dispersion curves to construct 2d group velocity maps and 3d distributions of s wave velocity we have used a new tomographic algorithm based on iterative linearized inversion we have performed a series of synthetic tests that demonstrate significantly higher resolution in the upper crust with this model compared to the local earthquake travel time tomography let model previously applied for the same station network beneath the southern flank of merapi we identify a large low velocity anomaly that can be split into two layers the upper layer reflects the 1 km thick sedimentary cover of volcanoclastic deposits the deeper anomaly at depths of 4 8 km may represent a magma reservoir with partially molten rock that feeds several volcanoes in central java beneath the merapi summit we observe another low velocity anomaly as deep as 8 km that may be associated with the active magma reservoir that feeds the eruptive activity of merapi in the southern portion of the study area in the lower crust we identify a low velocity anomaly that may represent the top of the pathways of volatiles and melts ascending from the slab that was previously inferred from the let model results we observe that this anomaly is clearly separate from the felsic magma reservoirs in the upper crust this article is protected by copyright all rights reserved

high frequency ambient noise tomography of southeast australia new constraints on tasmania s tectonic past 1 the island of tasmania at the southeast tip of australia is an ideal natural laboratory for ambient noise tomography as the surrounding oceans provide an energetic and relatively even distribution of noise sources we extract rayleigh wave dispersion curves from the continuous records of 104 stations with 15 km separation unlike most passive experiments of this type which observe very little coherent noise below a 5 s period we clearly detect energy at periods as short as 1 s thanks largely to the close proximity of oceanic microseisms on all sides the main structural elements of the eastern and northern tasmanian crust are revealed by inverting the dispersion curves between 1 and 12 s period for both group and phase velocity maps of particular significance is a pronounced band of low velocity observed across all periods that underlies the tamar river valley and continues south until dissipating in southeast tasmania together with evidence from combined active source and teleseismic tomography and heat flow data we interpret this region as a diffuse zone of strong deformation associated with the mid paleozoic accretion of oceanic crust along the eastern margin of proterozoic tasmania which has important implications for the evolution of the tasman orogen of eastern australia in the northwest a narrower low velocity anomaly is seen in the vicinity of the arthur lineament which may be attributed to local sediments and strong deformation and folding associated with the final phases of the tyennan orogeny

the southern zagros collisional orogen new insights from transdimensional trees inversion of seismic noise the natural environmental research council nerc grant ne r013500 1 and from the european union s horizon 2020 research and innovation program under marie sklodowska curie grant agreement 790203

the role of streamline curvature in sand dune dynamics evidence from field and wind tunnel measurements abstract field measurements on an unvegetated 10 m high barchan dune in oman are compared with measurements over a 1 200 scale fixed model in a wind tunnel both the field and wind tunnel data demonstrate similar patterns of wind and shear velocity over the dune confirming significant flow deceleration upwind of and at the toe of the dune acceleration of flow up the windward slope and deceleration between the crest and brink this pattern including the widely reported upwind reduction in shear velocity reflects observations of previous studies such a reduction in shear velocity upwind of the dune should result in a reduction in sand transport and subsequent sand deposition this is not observed in the field wind tunnel modelling using a near surface pulse wire probe suggests that the field method of shear velocity derivation is inadequate the wind tunnel results exhibit no reduction in shear velocity upwind of or at the toe of the dune evidence provided by reynolds stress profiles and turbulence intensities measured in the wind tunnel suggest that this maintenance of upwind shear stress may be a result of concave unstable streamline curvature these additional surface stresses are not recorded by the techniques used in the field measurements using the occurrence of streamline curvature as a starting point a new 2 d model of dune dynamics is deduced this model relies on the establishment of an equilibrium between windward slope morphology surface stresses induced by streamline curvature and streamwise acceleration adopting the criteria that concave streamline curvature and streamwise acceleration both increase surface shear stress whereas convex streamline curvature and deceleration have the opposite effect the relationships between form and process are investigated in each of three morphologically distinct zones the upwind interdune and concave toe region of the dune the convex portion of the windward slope and the crest brink region the applicability of the model is supported by measurements of the rate of sand transport and the change of the dune surface in the field

redefining dharwar craton southern granulite terrain boundary in south india from new seismological constraints abstract the southern part of the dharwar craton is an archean granulite terrain that continues further south and joins with the proterozoic southern granulite terrain sgt the linkage and the boundary between the dharwar craton and the sgt has been a subject of debate over the last 75 years based on adequate coverage of broadband seismological stations 80 over south india we generated3 d shear velocity image of the crust through joint inversion of the p receiver function and rayleigh wave group velocity dispersions derived from the cross correlation of ambient noise time series analysis the most significant finding is an unusually thick 15 28 km high velocity layer hvl with vs 4 0 km sin the lowermost crust beneath the south dharwar craton that continues southward in a most coherent fashion well beyond the southern limb of palghat cauvery shear zone pcsz widely considered to be the contact zone of the dharwar and sgt elsewhere in south india the high velocity layer is about 4 8 km thick similar to the global average we interpret this hvl as a mafic magmatic underplate of archean ancestry formed during granulite metamorphism the study suggests that the dharwar craton continues further south of the mapped orthopyroxene boundary to the palghat shear zone in a continuous manner

crust and upper mantle structure beneath southeast australia from ambient noise and teleseismic tomography abstract in the last decade the lithospheric structure beneath southeast australia has been intensively studied using passive seismic data from wombat the largest transportable seismic array in the southern hemisphere the two primary imaging methods that have been applied are ambient noise tomography for the crust and teleseismic tomography for the upper mantle despite these recent studies no attempt has yet been made to provide an integrated view of the crust mantle system here we perform teleseismic tomography using wombat data that includes a detailed crustal model from ambient noise tomography in the starting model a moho surface from the australian seismological reference earth model ausrem is also included this has the dual benefit of accounting for the unresolved crustal component of the teleseismic arrival time residuals and producing a model that reveals a high level of detail in both the crust and upper mantle our new integrated p wave model contains a number of noteworthy features including i low velocity anomalies in the lower crust and high velocity anomalies in the lithospheric mantle beneath the gawler craton and curnamona province which are of paleoproterozoic archean origin ii a marked velocity transition in the crust and lithospheric mantle near the moyston fault which we interpret as the boundary between the lachlan and delamerian orogens iii a rapid eastward decrease in upper mantle velocity 200 km inboard of the east coast of australia which is consistent with a marked thinning of the lithosphere iv an increase in upper mantle velocity north of the gawler craton and curnamona province which points to the presence of thicker lithosphere associated with the precambrian shield region of the australian continent v cenozoic intraplate basaltic volcanic centres distributed exclusively above the zone of thinner lithosphere inboard of the east coast with the exception of low volume leucitite volcanics

crustal radial anisotropy beneath the dabie orogenic belt from ambient noise tomography summary in this study we continue our previous work of imaging isotropic shear velocity to study the crustal radial anisotropy beneath the dabie orogen and surrounding regions by jointly analysing rayleigh wave and love wave dispersion curves in addition to processing the vertical component data to retrieve rayleigh waves we collect horizontal component continuous ambient noise data and retrieve love waves from cross correlations of horizontal component noise data between station pairs then we measure love phase velocity dispersion curves at periods from 8 to 35 s using a spectral method and perform surface wave tomography to obtain high resolution phase velocity maps finally we determine crustal radial anisotropy by inverting the local phase velocity dispersion curves of rayleigh and love waves our model of crustal radial anisotropy reveals complex anisotropic patterns associated with the dynamic processes of continent continent collisions and post collision reworking between the north china craton and the yangtze craton in the huabei basin the radial anisotropy is positive throughout the entire crust corresponding to areas with extensional tectonics developed since the middle mesozoic in the jianghan basin strong positive radial anisotropy in the middle and lower crust is observed most likely resulting from subhorizontal alignment of seismic anisotropic materials under the crustal extensional deformation in the eastern dabie orogenic belt the radial anisotropy beneath northern dabie complex ndc appears positive in the upper and lower crust and negative in the middle crust the positive radial anisotropy in the upper crust is probably because of the presence of igneous rocks with anisotropic minerals aligned subhorizontally under the action of the extensional tectonics during igneous extrusion and emplacement whereas the positive radial anisotropy in the lower crust is probably because that subhorizontal alignment of anisotropic materials induced by magmatic underplating formed after the delamination of the orogeny in the middle crust finite strains associated with the vertical intrusion of deep magma might cause crystalline anisotropic minerals aligned vertically resulting in observed negative radial anisotropy in the western dabie orogenic belt positive radial anisotropy is present in the whole crust except beneath the hong an ultrahigh pressure uhp area where radial anisotropy is negative in the middle crust similar to ndc the hong an uhp probably experienced similar thermal geodynamic processes as the eastern dabie and the negative radial anisotropy might be also the result of vertical alignment of anisotropic minerals caused by the vertical intrusion of deep magma strong localized negative radial anisotropy in the middle crust beneath the xinyang area is imaged most likely caused by the vertical alignment of anisotropic minerals crystallized from the vertically intruding mafic magma originated from the upper mantle during the volcanism

the tamar conductivity anomaly magneto variational measurements in eastern tasmania have shown the presence of a conductivity anomaly coinciding with the tamar lineament magneto telluric observations indicate a shallow body 2 5 km deep with a high conductivity 0 2 1 s m 1 analogue model measurements made at the university of victoria have been used to correct for the effect of the oceans surrounding tasmania rather than model the form of the conducting body the results have been interpreted in terms of current flowing in a nnw sse direction in a channel 40 km wide with a sharp eastern edge and a more gradual tapering to the west the most likely explanation of the high conductivity is fractured rock saturated with conducting pore fluids