litho1 0 an updated crust and lithospheric model of the earth we present the litho1 0 model which is a 1 tessellated model of the crust and uppermost mantle of the earth extending into the upper mantle to include the lithospheric lid and underlying asthenosphere the model is parameterized laterally by tessellated nodes and vertically as a series of geophysically identified layers such as water ice sediments crystalline crust lithospheric lid and asthenosphere litho1 0 is created by constructing an appropriate starting model and perturbing it to fit high resolution surface wave dispersion maps love and rayleigh group and phase over a wide frequency band 5 40 mhz we examine and discuss the model with respect to key lithospheric parameters such as average crustal velocity crustal thickness upper mantle velocity and lithospheric thickness we then compare the constructed model to those from a number of select studies at regional and global scales and find general consistency it appears that litho1 0 represents a reasonable starting model of the earth s shallow structure crust and uppermost mantle for the purposes in which these models are used such as traveltime tomography or in efforts to create a 3 d reference earth model the model matches surface wave dispersion over a frequency band wider than the band used in the inversion there are several avenues for improving the model in the future by including attenuation and anisotropy as well as making use of surface waves at higher frequency

shear wave structure of the south indian lithosphere from rayleigh wave phase velocity measurements we investigate the upper mantle shear wave speed structure beneath the south indian shield by measuring and modeling fundamental mode rayleigh wave phase velocity dispersion observed phase velocities for the south indian shield closely match those observed for the canadian shield we constrain the south indian crust using published receiver function results and invert the dispersion data for upper mantle shear wave structure the 155 km thick seismic lithosphere of the south indian shield is composed of a 35 km thick two layer crust and a 120 km thick high velocity upper mantle lid beneath the moho the average sn wave speed is 4 7 km sec 1 both sn travel times data and the dispersion data suggest a positive sub moho shear wave speed gradient beneath the seismic lithosphere there is a low velocity layer where the shear wave speed drops to 4 4 km sec 1

on crustal corrections in surface wave tomography summary mantle models from surface waves rely on good crustal corrections we investigated how far ray theoretical and finite frequency approximations can predict crustal corrections for fundamental mode surface waves using a spectral element method we calculated synthetic seismograms in transversely isotropic prem and in the 3 d crustal model crust2 0 on top of prem and measured the corresponding time shifts as a function of period we then applied phase corrections to the prem seismograms using ray theory and finite frequency theory with exact local phase velocity perturbations from crust2 0 and looked at the residual time shifts after crustal corrections residuals fall within the uncertainty of measured phase velocities for periods longer than 60 and 80 s for rayleigh and love waves respectively rayleigh and love waves are affected in a highly non linear way by the crustal type oceanic crust affects love waves stronger while rayleigh waves change most in continental crust as a consequence we find that the imperfect crustal corrections could have a large impact on our inferences of radial anisotropy if we want to map anisotropy correctly we should invert simultaneously for mantle and crust the latter can only be achieved by using perturbation theory from a good 3 d starting model or implementing full non linearity from a 1 d starting model

a global horizontal shear velocity model of the upper mantle from multimode love wave measurements surface wave studies in the 1960s provided the first indication that the upper mantle was radially anisotropic resolving the anisotropic structure is important because it may yield information on deformation and flow patterns in the upper mantle the existing radially anisotropic models are in poor agreement rayleigh waves have been studied extensively and recent models show general agreement less work has focused on love waves and the models that do exist are less well constrained than are rayleigh wave models suggesting it is the love wave models that are responsible for the poor agreement in the radially anisotropic structure of the upper mantle we have adapted the waveform inversion procedure of debayle ricard to extract propagation information for the fundamental mode and up to the fifth overtone from love waveforms in the 50 250 s period range we have tomographically inverted these results for a mantle horizontal shear wave speed model h z to transition zone depths we include azimuthal anisotropy 2 and 4 terms in the tomography but in this paper we discuss only the isotropic h z structure the data set is significantly larger almost 500 000 love waveforms than previously published love wave data sets and provides 17 000 000 constraints on the upper mantle h z structure sensitivity and resolution tests show that the horizontal resolution of the model is on the order of 800 1000 km to transition zone depths the high wave speed roots beneath the oldest parts of the continents appear to extend deeper for h z than for v z as in previous h z models but the resolution tests indicate that at least parts of these features could be artefacts the low wave speeds beneath the mid ocean ridges fade by 150 km depth except for the upper mantle beneath the east pacific rise which remains slow to 250 km depth the resolution tests suggest that the low wave speeds at deeper depths beneath the east pacific rise are not solely due to vertical smearing of shallow low wave speeds four prominent low wave speed features occur at transition zone depths one aligned along the east african rift one centred south of the indian peninsula one located south of new zealand and one in the south pacific ocean coinciding with the location of the south pacific superswell the low wave speed features south of new zealand and south of the indian peninsula correspond spatially with the two largest negative geoid lows on earth

radial seismic anisotropy as a constraint for upper mantle rheology abstract seismic shear waves that are polarized horizontally sh generally travel faster in the upper mantle than those that are polarized vertically sv and deformation of rocks under dislocation creep has been invoked to explain such radial anisotropy convective flow of the upper mantle may thus be constrained by modeling the textures that progressively form by lattice preferred orientation lpo of intrinsically anisotropic grains while azimuthal anisotropy has been studied in detail the radial kind has previously only been considered in semi quantitative models here we show that radial anisotropy averages as well as radial and azimuthal anomaly patterns can be explained to a large extent by mantle flow if lateral viscosity variations are taken into account we construct a geodynamic reference model which includes lpo formation based on mineral physics and flow computed using laboratory derived olivine rheology previously identified anomalous v sv regions beneath the east pacific rise and relatively fast v sh regions within the pacific basin at 150 km depth can be linked to mantle upwellings and shearing in the asthenosphere respectively continental anisotropy at shallow 50 km depth is under predicted and these deviations are in quantitative agreement with the expected signature of frozen in stochastically oriented anisotropy from past tectonic episodes we also consider two end member models of lpo formation for wet and dry conditions for the asthenosphere 150 km allowing for lateral variations in volatile content the residual signal can be much reduced and the inferred volatile patterns underneath the pacific appear related to plume activity in deeper layers 250 km anisotropy indicates that small scale convection disrupts plate scale shear underneath old oceanic lithosphere we suggest that studying deviations from comprehensive geodynamic reference models or residual anisotropy can provide new insights into the nature and dynamics of the asthenosphere

global anisotropic phase velocity maps for higher mode love and rayleigh waves summary it is well established that the earth s uppermost mantle is anisotropic but there are no clear observations of anisotropy in the deeper parts of the mantle surface waves are well suited to observe anisotropy since they carry information about both radial and azimuthal anisotropy fundamental mode surface waves for commonly used periods up to 200 s are sensitive to structure in the first few hundred kilometres and therefore do not provide information on anisotropy below higher mode surface waves have sensitivities that extend to and beyond the transition zone and should thus give insight about azimuthal anisotropy at greater depths we have measured higher mode love and rayleigh phase velocities using a model space search approach which provides us with consistent relative uncertainties from measurement to measurement and from mode to mode from these phase velocity measurements we constructed global anisotropic phase velocity maps prior to inversion we determine the optimum relative weighting for anisotropy we present global azimuthal phase velocity maps for higher mode rayleigh waves up to the sixth higher mode and love waves up to the fifth higher mode with corresponding average model uncertainties the anisotropy we derive is robust within the uncertainties for all modes given the ray theoretical sensitivity kernels of rayleigh and love wave modes the source of anisotropy is complex but mainly located in the asthenosphere and deeper our models show a good correspondence with other studies for the fundamental mode but we have been able to achieve higher resolution

anisotropic shear wave velocity structure of the earth s mantle a global model 1 we combine a new large data set of surface wave phase anomalies long period waveforms and body wave travel times to construct a three dimensional model of the anisotropic shear wave velocity in the earth s mantle our modeling approach is improved and more comprehensive compared to our earlier studies and involves the development and implementation of a new spherically symmetric reference model simultaneous inversion for velocity and anisotropy as well as discontinuity topographies and implementation of nonlinear crustal corrections for waveforms a comparison of our new three dimensional model s362ani with two other models derived from comparable data sets but using different techniques reveals persistent features 1 strong 200 km thick high velocity anomalies beneath cratons likely representing the continental lithosphere underlain by weaker fast anomalies extending below 250 km which may represent continental roots 2 weak velocity heterogeneity between 250 and 400 km depths 3 fast anomalies extending horizontally up to 2000 3000 km in the mantle transition zone beneath subduction zones 4 lack of strong long wavelength heterogeneity below 650 km suggesting inhibiting character of the upper mantle lower mantle boundary and 5 slow velocity superplumes beneath the pacific and africa the shear wave radial anisotropy is strongest at 120 km depth in particular beneath the central pacific lateral anisotropic variations appreciably improve the fit to data that are predominantly sensitive to the uppermost and lowermost mantle but not to the waveforms that control the transition zone and midmantle depths tradeoffs between lateral variations in velocity and anisotropy are negligible in the uppermost mantle but noticeable at the bottom of the mantle

a three dimensional radially anisotropic model of shear velocity in the whole mantle summary we present a 3 d radially anisotropic s velocity model of the whole mantle saw642an obtained using a large three component surface and body waveform data set and an iterative inversion for structure and source parameters based on non linear asymptotic coupling theory nact the model is parametrized in level 4 spherical splines which have a spacing of 8 the model shows a link between mantle flow and anisotropy in a variety of depth ranges in the uppermost mantle we confirm observations of regions with vsh vsv starting at 80 km under oceanic regions and 200 km under stable continental lithosphere suggesting horizontal flow beneath the lithosphere we also observe a vsv vsh signature at 150 300 km depth beneath major ridge systems with amplitude correlated with spreading rate for fast spreading segments in the transition zone 400 700 km depth regions of subducted slab material are associated with vsv vsh while the ridge signal decreases whilethemid mantlehasloweramplitudeanisotropy vsv in the lowermost 300 km which appears to be a robust conclusion despite an error in our previous paper which has been corrected here the 3 d deviations from this signature are associated with the large scale low velocity superplumes underthecentralpacificandafrica suggestingthatvsh vsv isgeneratedinthepredominant horizontal flow of a mechanical boundary layer with a change in signature related to transition to upwelling at the superplumes

dynamical links between the decadal variability of the oyashio and kuroshio extensions abstractrather than a single and continuous boundary current outflow long term satellite observations reveal that the oyashio extension oe in the north pacific subarctic gyre comprises two independent northeast southwest slanted front systems with a mean latitude along 40 n the western oe front exists primarily west of 153 e and is a continuation of the subarctic gyre western boundary current the eastern oe front also appearing along 40 n is located between 153 and 170 e whose entity is disconnected from its western counterpart during 1982 2016 both of the oe fronts exhibit prominent decadal fluctuations although their signals show little contemporaneous correlation an upper ocean temperature budget analysis based on the estimating the circulation and climate of the ocean phase ii ecco2 state estimate reveals that the advective temperature flux convergence plays a critical role in determining the low frequency temperature changes relating to the oe fronts specifically the western oe f

waveform tomography reveals channeled flow at the base of the oceanic asthenosphere understanding the relationship between different scales of convection that drive plate motions and hotspot volcanism still eludes geophysicists using full waveform seismic tomography we imaged a pattern of horizontally elongated bands of low shear velocity most prominent between 200 and 350 kilometers depth which extends below the well developed low velocity zone these quasi periodic fingerlike structures of wavelength 2000 kilometers align parallel to the direction of absolute plate motion for thousands of kilometers below 400 kilometers depth velocity structure is organized into fewer undulating but vertically coherent low velocity plumelike features which appear rooted in the lower mantle this suggests the presence of a dynamic interplay between plate driven flow in the low velocity zone and active influx of low rigidity material from deep mantle sources deflected horizontally beneath the moving top boundary layer

mantle transition zone structure beneath the south pacific superswell and evidence for a mantle plume underlying the society hotspot abstract underside reflections of shear waves from the discontinuities at 410 and 660 km depth are used to map lateral variations in the thickness of the mantle transition zone beneath the south pacific superswell and surrounding regions differential travel times of reflected waves indicate that the transition zone is about 25 km thinner than normal and thus hotter than normal over an area 500 km or less in diameter beneath the society hotspot there is no general difference however in transition zone thickness between the superswell area and its surroundings our observations support the inference that the thermal flux from lower to upper mantle beneath the south pacific superswell occur on the lateral scale of a mantle plume several hundred kilometers rather than that of a superplume several thousand kilometers

dolomite carbonate replacement textures in veins cutting carboniferous rocks in east fife abstract carbonate veins cutting carboniferous sediments in fife scotland contain three apparently paragenetically equivalent types of ferroan dolomite all of which show somewhat unusual fabrics the most spectacular of these are fence textured crystals comprising an open rhombic network of inclusion rich dolomite which is partially filled by later syntaxial inclusion free ankerite the more common paragenetic equivalents to the fence textured dolomite are dolomite filled rhombic moulds and two dolomite intergrowth fabrics all three fabrics appear to indicate dolomite replacement of a rhombohedral carbonate precursor and seem to reflect different degrees of development in a common sequence of events 1 precipitation of a metastable phase 2 precipitation of dolomite 3 precipitation of dolomite coupled with dissolution of the metastable phase neomorphism 4 dissolution of the metastable phase this progression is compatible with gradual cooling within a series of hydrothermal systems centred on adjacent namurian volcanics and the range of fabrics developed by the dolomite may reflect differential cooling in different parts of these hydrothermal systems the ankerite which partially fills the fence texture and the rhombic moulds also occurs in veins cutting stephanian rocks indicating a much later origin

inferring upper mantle structure by full waveform tomography with the spectral element method summary mapping the elastic and anelastic structure of the earth s mantle is crucial for understanding the temperature composition and dynamics of our planet in the past quarter century global tomography based on ray theory and first order perturbation methods has imaged long wavelength elastic velocity heterogeneities of the earth s mantle however the approximate techniques upon which global tomographers have traditionally relied become inadequate when dealing with crustal structure as well as short wavelength or large amplitude mantle heterogeneity the spectral element method on the other hand permits accurate calculation of wave propagation through highly heterogeneous structures and is computationally economical when coupled with a normal mode solution and applied to a restricted region of the earth such as the upper mantle sem importantly sem allows a dramatic improvement in accounting for the effects of crustal structure here we develop and apply a new hybrid method of tomography which allows us to leverage the accuracy of sem to model fundamental and higher mode long period 60 s waveforms we then present the first global model of upper mantle velocity and radial anisotropy developed using sem our model semum confirms that the long wavelength mantle structure imaged using approximate semi analytic techniques is robust and representative of the earth s true structure furthermore it reveals structures in the upper mantle that were not clearly seen in previous global tomographic models we show that semum favourably compares to and rivals the resolving power of continental scale studies this new hybrid approach to tomography can be applied to a larger and higher frequency data set in order to gain new insights into the structure of the lower mantle and more robustly map seismic structure at the regional and smaller scales

assessment of global phase velocity models summary we construct new love and rayleigh wave phase velocity models based on measurements made from an aspherical starting model and strict data quality control derived from cluster analyses these new models are in good agreement with previous ones and the question arises whether the slight changes show an improved capacity to explain the data to this effect we propose an objective method to compare different phase velocity models published in recent literature the method is based on comparing calculated synthetics to raw seismograms we find a reassuring convergence between all the models we tested at the longest periods and more scatter at the shorter periods at 40 s the different models show gains of up to 3 5 cycles over prem generally the higher the gain over prem the smaller the period considered which confirms that the earth s heterogeneity is strongest in the uppermost parts of the earth apart from assessing different models against each other our method gives an estimate comparable to cluster analyses of the underlying data errors that went into the construction of the models themselves moreover ray coverage is still far from perfect for constructing phase velocity models as a result we find that without precaution degree zero is biased through spectral leakage by 0 1 to 0 2 per cent with respect to prem the earliest information concerning the earth s 3 d structure came from surface waves when tams 1921 noticed clear velocity differences for waves propagating along continental versus oceanic paths gutenberg 1924 attempted an explanation of such differences in terms of regional variations in crustal structure when he noticed that short period surface waves are more sensitive to crustal structure than long period ones this led the way to intensive studies both theoretical and observational to link dispersive properties of surface waves to the internal structure of the earth the first regional models of the earth s dispersive properties of crust and upper mantle are summarized in papers by brune 1969 and dorman 1969 respectively with the start of digital recording of seismograms in the late

a global shear velocity model of the upper mantle from fundamental and higher rayleigh mode measurements we present dr2012 a global sv wave tomographic model of the upper mantle we use an extension of the automated waveform inversion approach of debayle 1999 which improves our mapping of the transition zone with extraction of fundamental and higher mode information the new approach is fully automated and has been successfully used to match approximately 375 000 rayleigh waveforms for each seismogram we obtain a path average shear velocity and quality factor model and a set of fundamental and higher mode dispersion and attenuation curves we incorporate the resulting set of path average shear velocity models into a tomographic inversion in the uppermost 200 km of the mantle sv wave heterogeneities correlate with surface tectonics the high velocity signature of cratons is slightly shallower approximate to 200 km than in other seismic models thicker continental roots are not required by our data but can be produced by imposing a priori a smoother model in the vertical direction regions deeper than 200 km show no velocity contrasts larger than 1 at large scale except for high velocity slabs within the transition zone comparisons with other seismic models show that current surface wave datasets allow to build consistent models up to degrees 40 in the upper 200 km of the mantle the agreement is poorer in the transition zone and confined to low harmonic degrees 10

global love wave overtone measurements 1 love wave phase velocities for fundamental and higher modes are difficult to measure because the different modes cannot easily be separated following yoshizawa and kennett 2002 we generate suites of path specific onedimensional shear wave velocity profiles using the neighbourhood algorithm of sambridge 1999a from this family of o 10 4 models both fundamental and higher mode phase velocities with mutually consistent uncertainties are calculated we have fully automated the method and analysed over forty thousand love wave seismograms from the gdsn and geoscope global networks from 1994 2004 our phase velocity measurements agree remarkably well with previous studies but we have been able to enlarge the available dataset dramatically we present global love wave phase velocity maps up to the fifth overtone with unprecedented resolution due to the improved path coverage comparing these maps to existing tomographic models we discern evidence of significant anisotropy inthe lower mantlearound a depth of 1000 km in the pacific citation visser k s lebedev j trampert and b l n kennett 2007 global love wave overtone measurements geophys res lett 34 l03302

savani a variable resolution whole mantle model of anisotropic shear velocity variations based on multiple data sets we present a tomographic model of radially anisotropic shear velocity variations in the earth s mantle based on a new compilation of previously published data sets and a variable block parameterization adapted to local raypath density we employ ray theoretical sensitivity functions to relate surface wave and body wave data with radially anisotropic velocity perturbations our database includes surface wave phase delays from fundamental modes up to the sixth overtone measured at periods between 25 and 350 s as well as cross correlation traveltimes of major body wave phases before inversion we apply crustal corrections using the crustal model crust2 0 and we account for azimuthal anisotropy in the upper mantle using ray theoretical corrections based on a global model of azimuthal anisotropy while being well correlated with earlier models at long spatial wavelength our preferred solution savani additionally delineates a number of previously unidentified structures due to its improved resolution in areas of dense coverage this is because the density of the inverse grid ranges between 1 25 in well sampled and 5 in poorly sampled regions allowing us to resolve regional structure better than it is typically the case in global s wave tomography our model highlights i a distinct ocean continent anisotropic signature in the uppermost mantle ii an oceanic peak in above average 1 which is shallower than in previous models and thus in better agreement with estimates of lithosphere thickness and iii a long wavelength pattern of 1 associated with the large low shear velocity provinces in the lowermost mantle

global azimuthal seismic anisotropy and the unique plate motion deformation of australia differences in the thickness of the high velocity lid underlying continents as imaged by seismic tomography have fuelled a long debate on the origin of the roots of continents1 2 3 4 5 some of these differences may be reconciled by observations of radial anisotropy between 250 and 300 km depth with horizontally polarized shear waves travelling faster than vertically polarized ones2 this azimuthally averaged anisotropy could arise from present day deformation at the base of the plate as has been found for shallower depths beneath ocean basins6 such deformation would also produce significant azimuthal variation owing to the preferred alignment of highly anisotropic minerals7 here we report global observations of surface wave azimuthal anisotropy which indicate that only the continental portion of the australian plate displays significant azimuthal anisotropy and strong correlation with present day plate motion in the depth range 175 300 km beneath other continents azimuthal anisotropy is only weakly correlated with plate motion and its depth location is similar to that found beneath oceans we infer that the fast moving australian plate contains the only continental region with a sufficiently large deformation at its base to be transformed into azimuthal anisotropy simple shear leading to anisotropy with a plunging axis of symmetry may explain the smaller azimuthal anisotropy beneath other continents

surface waveform tomography of the turkish iranian plateau summary the middle east is a tectonically complex region consisting of terrains as diverse as precam brian shields and young orogens the dominant tectonic feature is the turkish iranian plateau a recently elevated seismically active region along the zagros bitlis suture which results from the collision of the arabian plate with eurasia in this study we use surface waveform tomography to elucidate the upper mantle shear wave velocity structure beneath the turkish iranian plateau and adjacent regions the main large scale feature in the tomographic model is a low shear wave velocity anomaly in the uppermost mantle beneath the plateau this low velocity feature correlates with a long wavelength free air gravity anomaly and with recent volcanism whose geochemistry has a lower lithospheric mantle signature seismology gravity and volcanism all suggest the presence of a thin lithosphere and warm upper mantle beneath the turkish iranian plateau the upper mantle low shear wave velocity zone the high free air gravity and the deep lithospheric source depth for the basaltic volcanism are all consistent with a partial delamination of the lithosphere as a result of earlier lithospheric thickening resulting from the continental collision

full waveform tomography of the upper mantle in the south atlantic region imaging a westward fluxing shallow asthenosphere abstract a prominent feature of the south atlantic region is its strongly asymmetric residual bathymetry across the ocean basin it has been suggested that the residual bathymetry is dynamic in nature arising from the large slow velocity seismic anomaly located in the lower mantle beneath the african plate unfortunately the pattern of mantle heterogeneity particularly in the upper mantle is not well known owing to the sparsity of seismic stations and the existence of large aseismic regions on the african and south american plates here we present a new seismic tomographic study of the south atlantic upper mantle our model is based on a full seismic waveform inversion of 4000 high quality seismograms for isotropic 3 d seismic structure using a powerful adjoint methodology capable of extracting maximum information from each seismogram the theory requires simulation of seismic wave propagation in 3 d heterogeneous earth models computed with a spectral element method where the differences between observed and synthetic seismograms are quantified using phase misfits obtained through a time frequency transform the model images a continuous channel of pronounced slow seismic velocity in the shallow sublithospheric mantle between 150 and 300 km depth that branches in between the cratonic roots under the african and south american continents at greater depth below 300 350 km the slow anomalies are less pronounced and a change in the convective planform is indicated by isolated round shaped patches in an overall faster mantle it is possible that the depthwise change of the convective planform from vertical to horizontal advection of hot buoyant material in a low viscosity asthenosphere can reconcile the anomalous residual bathymetry in the region and we present a simple fluid dynamic model of pressure driven flow to assess the feasibility of this scenario

multimode surface waveform tomography of the pacific ocean a closer look at the lithospheric cooling signature summary we present a regional surface waveform tomography of the pacific upper mantle obtained using an automated multimode surface waveform inversion technique on fundamental and higher mode rayleigh waves to constrain the vsv structure down to 400 km depth we have improved on previous implementations of this technique by robustly accounting for the effects of uncertainties in earthquake source parameters in the tomographic inversion we have furthermore improved path coverage in the south pacific region by including rayleigh wave observations from the french polynesian pacific lithosphere and upper mantle experiment deployment this improvement has led to imaging of vertical low velocity structures associated with hotspots within the south pacific super swell region we have produced an age dependent average cross section for the pacific ocean lithosphere and found that the increase in vsv with age is broadly compatible with a half space cooling model of oceanic lithosphere formation we cannot confirm evidence for a pacific wide reheating event our synthetic tests show that detailed interpretation of average vsv trends across the pacific ocean may be misleading unless lateral resolution and amplitude recovery are uniform across the region a condition that is difficult to achieve in such a large oceanic basin with current seismic stations

theoretical background for continental and global scale full waveform inversion in the time frequency domain summary we propose a new approach to full seismic waveform inversion on continental and global scales this is based on the time frequency transform of both data and synthetic seismograms with the use of time and frequency dependent phase and envelope misfits these misfits allow us to provide a complete quantification of the differences between data and synthetics while separating phase and amplitude information the result is an efficient exploitation of waveform information that is robust and quasi linearly related to earth s structure thus the phase and envelope misfits are usable for continental and global scale tomography that is in a scenario where the seismic wavefield is spatially undersampled and where a 3 d reference model is usually unavailable body waves surface waves and interfering phases are naturally included in the analysis we discuss and illustrate technical details of phase measurements such as the treatment of phase jumps and instability in the case of small amplitudes the frechet kernels for phase and envelope misfits can be expressed in terms of their corresponding adjoint wavefields and the forward wavefield the adjoint wavefields are uniquely determined by their respective adjoint source time functions we derive the adjoint source time functions for phase and envelope misfits the adjoint sources can be expressed as inverse time frequency transforms of a weighted phase difference or a weighted envelope difference in a comparative study we establish connections between the phase and envelope misfits and the following widely used measures of seismic waveform differences 1 cross correlation time shifts 2 relative rms amplitude differences 3 generalized seismological data functionals and 4 the l2 distance between data and synthetics used in time domain full waveform inversion we illustrate the computation of frechet kernels for phase and envelope misfits with data from an event in the west irian region of indonesia recorded on the australian continent the synthetic seismograms are computed for a heterogeneous 3 d velocity model of the australian upper mantle with a spectral element method the examples include p body waves rayleigh waves and s waves interfering with higher mode surface waves all the kernels differ from the more familar kernels for cross correlation time shifts or relative rms amplitude differences the differences arise from interference effects 3 d earth s structure and waveform dissimilarities that are due to waveform dispersion in the heterogeneous earth

finite frequency effects in global surface wave tomography summary we compare traditional ray theoretical surface wave tomography with finite frequency tomography using 3 d born sensitivity kernels for long period fundamental mode dispersion measurements the 3 d kernels preserve sidelobes beyond the first fresnel zone and fully account for the directional dependence of surface wave scattering and the effects of timedomain tapering and seismic source radiation tomographic inversions of love and rayleigh phase delay measurements and synthetic checkerboard tests show that 1 small scale s wave velocity anomalies are better resolved using finite frequency sensitivity kernels especially in the lowermost upper mantle 2 the resulting upper mantle heterogeneities are generally stronger in amplitude than those recovered using ray theory and 3 finite frequency tomographic models fit long period dispersion data better than ray theoretical models of comparable roughness we also examine the reliability of 2 d phase velocity sensitivity kernels in global surface wave tomography and show that phase velocity kernels based upon a forwardscattering approximation or previously adopted geometrical simplifications do not reliably account for finite frequency wave propagation effects 3 d sensitivity kernels with full consideration of directional dependent seismic scattering are the preferred method of inverting long period dispersion data finally we derive 2 d boundary sensitivity kernels for lateral variations in crustal thickness and show that finite frequency crustal effects are not negligible in long period surface wave dispersion studies especially for paths along continent ocean boundaries unfortunately we also show that in global studies linear perturbation theory is not sufficiently accurate to make reliable crustal corrections due to the large difference in thickness between oceanic and continental crust

global love wave phase velocity variation and its significance to plate tectonics abstract global love wave phase velocity variation was constructed for periods between 80 and 200 s by using approximately 9000 paths from 971 earthquakes with m 5 5 the data set was from gdsn and geoscope networks between 1980 and 1987 we examined both the spherical harmonic expansion method and the block parameterization method with a simple constant damping parameter approach synthetic tests showed that more accurate results were obtained by the block parameterization method than by the spherical harmonic expansion method we adopted the block inversion method with a nearly equal area block 5 5 near the equator discretization the general pattern of the resulting maps were consistent with previous global and local studies with a discretization of 5 by 5 the maps were detailed enough to test some plate tectonic models for the pacific atlantic and indian oceans surface wave velocities increased smoothly to plate ages older than 100 ma simple forward modeling showed that seismic phase velocity variation with a continuous thickening of lithosphere up to about 150 ma fits the present observation disagreeing with the model deduced from the heat flow and ocean depth data which change variations at about 60 80 ma the seismic phase velocity variations in different oceans showed systematic differences at younger ages and convergence beyond 100 ma the difference at younger ages implies a failure of scaling derived from a simple thermal boundary layer model for oceanic plates age seismic phase velocity relationships on each side of ridges were also examined and asymmetric velocity variations were found which suggests differences in thermal states from one side of the ridge to the other in order to further examine the thermal state of the lithosphere average age phase velocity relations were established for each ocean and subtracted from phase velocity variation maps the results indicated broad low velocity regions in the south pacific super swell region the south and west indian ocean and high velocity regions east of the east pacific rise and in the north to northeast indian ocean the results reflect the asymmetry of phase velocity variation about ridges there is some correlation between hot spot locations and low velocity anomalies but additional large scale thermal anomalies exist under old oceanic plate

global radially anisotropic mantle structure from multiple datasets a review current challenges and outlook abstract since the 1960s seismologists have mapped anisotropy in the uppermost mantle the mantle transition zone and the d region when combined with constraints from mineral physics and geodynamics anisotropy provides critical information on the geometry of mantle flow here we review the theory early work recent tomographic models and experimental constraints on radial anisotropy we discuss current challenges in resolving radial anisotropy seismically in particular we show that it is highly beneficial to use multiple datasets in inversions for anisotropy notably short period group velocity data with strong sensitivity to the crust we present a new whole mantle model of radial anisotropy based on surface wave and body wave travel time data along with incorporated moho perturbations our whole mantle model shares common features with previous global models and is consistent with results from several high resolution regional studies

global shear speed structure of the upper mantle and transition zone s u m m a r y the rapid expansion of broad band seismic networks over the last decade has paved the way for a new generation of global tomographic models significantly improved resolution of global upper mantle and crustal structure can now be achieved provided that structural information is extracted effectively from both surface and body waves and that the effects of errors in the data are controlled and minimized here we present a new global vertically polarized shear speed model that yields considerable improvements in resolution compared to previous ones for a variety of features in the upper mantle and crust the model sl2013sv is constrained by an unprecedentedly large set of waveform fits 3 4 of a million broad band seismograms computed in seismogram dependent frequency bands up to a maximum period range of 11 450 s automated multimode inversion of surface and s wave forms was used to extract a set of linear equations with uncorrelated uncertainties from each seismogram the equations described perturbations in elastic structure within approximate sensitivity volumes between sources and receivers going beyond ray theory we calculated the phase of every mode at every frequency and its derivative with respect to sand p velocity perturbations by integration over a sensitivity area in a 3 d reference model the normally small perturbations of the 3 d model required to fit the waveforms were then linearized using these accurate derivatives the equations yielded by the waveform inversion of all the seismograms were simultaneously inverted for a 3 d model of shear and compressional speeds and azimuthal anisotropy within the crust and upper mantle elaborate outlier analysis was used to control the propagation of errors in the data source parameters timing at the stations etc the selection of only the most mutually consistent equations exploited the data redundancy provided by our data set and strongly reduced the effect of the errors increasing the resolution of the imaging our new shear speed model is parametrized on a triangular grid with a 280 km spacing in well sampled continental domains lateral resolution approaches or exceeds that of regionalscale studies the close match of known surface expressions of deep structure with the distribution of anomalies in the model provides a useful benchmark in oceanic regions spreading ridges are very well resolved with narrow anomalies in the shallow mantle closely confined near the ridge axis and those deeper down to 100 120 km showing variability in their width and location with respect to the ridge major subduction zones worldwide are well captured extending from shallow depths down to the transition zone the large size of our waveform fit data set also provides a strong statistical foundation to re examine the validity field of the jwkb approximation and surface wave ray theory our analysis shows that the approximations are likely to be valid within certain time frequency portions of most seismograms with high signal to noise ratios and these portions can be identified using a set of consistent criteria that we apply in the course of waveform fitting

global mantle shear velocity model developed using nonlinear asymptotic coupling theory we present a three dimensional shear velocity model of the whole mantle developed using s h waveform data the model is expressed horizontally in terms of spherical harmonics up to degree 12 and vertically in terms of legendre polynomials up to degrees 5 and 7 in the upper and lower mantle respectively what distinguishes this model from other tomographic models published to date is 1 the theoretical normal mode based wave propagation approach where we include across branch mode coupling terms in order to model the body wave sensitivity to structure along the path more accurately 2 the wave packet weighting scheme which allows to balance contributions from high amplitude and low amplitude phases increasing the resolution in some parts of the mantle we also relax the constraints on the moho depth which is allowed to vary in the inversion thus absorbing some uncertainties in crustal structure the resulting model is generally in good agreement with other recent global mantle s velocity models and with some regional models the rms profile with depth has more power than other models in the upper mantle lower mantle transition region and the zone of increased power and low degree structure near the base of the mantle is confined to the last 500 km in depth this model provides a particularly good fit to the non hydrostatic geoid through harmonic degree 12 79 variance reduction as well as good fits to observed splitting functions of s velocity sensitive mantle modes indicating that both large scale and small scale features are really well constrained