tomographic inversion of p410s delay times for simultaneous determination of p and s velocities of the upper mantle beneath the baltic shield abstract teleseismic data recorded by stations in the swedish national seismic network snsn are used for a study of upper mantle structure beneath the baltic shield using the receiver function technique the data show very clear conversions from the 410 and 660 km discontinuities the signals associated with p to s conversions at these discontinuities arrive 1 2 s earlier than predicted by global models such as iasp91 or prem we interpret this as a manifestation of higher than average velocities in the mantle beneath the shield consistent with lower than average global temperatures for a 1400 km profile along the network we observe variations of around 1 second in delay times of p410s and slightly less for p660s under the assumption that the mantle discontinuities are at a given constant depth the delay times of the mantle converted phases are tomographically inverted to reveal p and s velocity structure below the stations synthetic tests show that this tomographic inversion has the potential to resolve p and s velocity variations at structural scales adequate for upper mantle studies results from application to real data appear to be consistent with independently produced mantle velocity structures deduced from normal tomographic arrival time data for the p velocity model a north dipping body of relatively low velocity is found for the central part of the profile at 58 64 n a sharp contrast from low to high velocities that may be associated with the proterozoic archean boundary is found at 66 n

regional and teleseismic events recorded across the tesz during polonaise 97 abstract 20 polish short period three component stations were continuously operating for three weeks during polonaise 97 in the contact zone between palaeozoic and precambrian platforms in poland the distances between seismometers were about 20 km and the digitization interval was 0 02 s besides the shots a few regional events from the lubin area and teleseismic events mainly from the se backazimuth were also recorded interpretation of traveltimes for p and s waves for regional events using a simplified lt 7 model of crustal structure for theoretical calculation allowed correction of their origin time the same model can also explain the traveltime residuals of p waves for teleseismic events the main features of the division of poland into two platforms by the teisseyre tornquist tectonic zone ttz is seen both in the shape of residuals of teleseismic phases and in the receiver function a passive seismic experiment made during polonaise 97 as a reconnaissance for future teleseismic tomography experiment tor 2 gave quite promising results however to make a traveltime tomography and receiver function analysis the duration of data acquisition should be about half a year

shear wave velocity variations in the upper mantle beneath central europe summary a new model eur s91 of shear wave velocity variations in the upper mantle beneath central europe and surrounding regions down to a depth of 670km is presented the model is derived from the inversion of the waveforms of 217 seismograms using the partitioned waveform inversion method for the seismogram in the time window from the s wave arrival to the fundamental mode of the rayleigh wave the seismograms were mostly assembled from digitally recording long period and broad band stations in europe the resulting 3 d model accurately predicts most of the observed waveforms in a wide band of frequencies body waves were fit for frequencies up to 60mhz the fundamental rayleigh mode which at high frequencies is more prone to scattering and multipathing was generally low passed at 25 mhz the resolving power of the data set depends strongly on the density of available wave paths and varies as a function of geographical position small scale heterogeneities like the subducted lithosphere in the hellenic collision zone were imaged in the region with the highest density of wave paths which indicates an optimum resolution of better than 200 km the main new results of this study pertain to the transition between east and central europe we present new information about the structure below the tornquist teisseyre zone ttz the ttz is generally regarded as the boundary between the precambrian crust of the baltic shield russian platform and the younger crust of central europe our 3 d s velocity model reveals that below this line a sharp lateral boundary extends down to at least 140 km depth with high velocities beneath the baltic shield and russian platform contrasting to the low velocities beneath the younger regions of europe the observed velocity contrast across the ttz is largest between the pannonian basin and the russian platform where it is equal to 12 per cent at 80 km depth at depths of 300 400 km the ttz is underlain by a zone of low s velocity which indicates a local thinning of the deeply rooted high velocity structure or tectosphere that underlies most of eastern europe in addition to these new results on the transition region between east and central europe a number of features that are present in other tomographic results have been confirmed the precambrian provinces of europe are characterized by high s velocities low velocities are found beneath the pannonian basin the western mediterranean northern aegean sea turkey and a small region south west of the massif central the lithosphere beneath the paris basin has a positive s velocity anomaly the resolution of all these anomalies has been established with sensitivity tests

anisotropy across the sorgenfrei tornquist zone from shear wave splitting abstract during the tor 1 passive seismic experiment in 1996 97 a maximum of 139 temporary seismograph stations were operating over the sorgenfrei tornquist zone stz in an area extending from northern germany through denmark to central sweden one of the objectives was to study horizontal anisotropy directions in the subcrustal lithosphere and asthenosphere across the trans european suture zone to achieve this goal broad band and intermediate period 5 s data of the tor 1 stations and additional stations of permanent networks grsn geofon were analysed for splitting of sks and skks phases as a result of the relatively dense station spacing the method offers good lateral resolution of anisotropy preliminary results suggest that the directions of the fast horizontal s wave velocity are affected by the stz in central europe and southern sweden far away from the stz fast s wave directions are approximately e w while they turn more northerly closer to the stz where they are approximately parallel to the trend of the stz no significant shear wave splitting was observed north of 57 n and east of 14 e small delay times between 0 2 and 0 5 s observed at the northernmost tor 1 station t40s and t60s may be controlled by anisotropy in a thickened crust the mantle contribution of horizontal anisotropy within the stz is probably constrained to an approximately 60 km thick zone in the depth range between 70 and 300 km the observations are consistent with a model where azimuthal anisotropy is not governed by present day mantle flow in the asthenosphere but rather is frozen into the subcrustal lithosphere during the last episode of tectonic activity

seismic models of the lower lithosphere beneath the southern baltic sea between sweden and poland abstract based on recordings from the northern part of the baltic sea black sea profile and eugeno s profile 4 2 d seismic models have been constructed for a profile across the southwestern part of the east european platform from southern sweden to northern poland the thickness of the crust along the profile varies from 33 to 47 km the moho p wave velocity is 8 0 8 3 km s the uppermost mantle has a fine structure with alternating layers of higher and lower velocities down to a depth of about 120 km three alternating high and low velocity layers have been modelled the velocities vary between 8 2 and 8 7 km s in the high velocity layers and 8 0 and 8 5 km s in the low velocity layers a tendency of the depth of the moho and the depth of the uppermost mantle seismic boundaries to increase towards the southeast is observed

crustal structure of the mid polish trough beneath the teisseyre tornquist zone seismic profile abstract a new seismic refraction and wide angle reflection experiment in the teisseyre tornquist zone ttz in poland was conducting during july 1993 as an international polish finnish german and swedish co operation the ttz profile running in an se nw direction was exactly located in the central part of the mid polish trough in the zone of maximum subsidence from upper permian to upper cretaceous 19 shot points were placed along the 450 km profile the interval between the shot points was about 25 km 31 explosions 90 to 1000 kg of dynamite were recorded in two deployments using 135 modern three component seismic stations with spacing of the recording sites of about 1 7 km in this area the depth of the consolidated basement with a velocity of about 5 7 5 8 km s is 5 to 12 km deep nevertheless the p wave velocity is very low vp

u pb geochronology of monazite in precambrian tuffs reveals depositional and metamorphic histories abstract uranium lead geochronology of zircon in felsic tuffs plays a key role in the development of chronostratigraphic frameworks for sedimentary successions this is particularly true for precambrian basins where biostratigraphy is of limited use for age determination or stratigraphic correlation although zircon is widely used to date tuffs it can yield null results due to the presence of xenocrystic populations or isotopic resetting other potential u pb chronometers such as monazite which also crystallize from felsic magmas are largely unreported from felsic tuff layers consequently there has been a lack of studies to evaluate the potential of monazite for u pb isotope geochronology of tuffs we present results of in situ u pb ion microprobe dating of monazite that co exists with zircon in felsic tuffs from two precambrian basins the earaheedy basin frere formation in western australia and the bushveld basin lephala formation in southern africa we show that 207pb 206pb ages from monazite in felsic tuffs from the frere formation 1891 9 ma and the lephala formation 2307 9 ma are identical to zircon ages from the respective tuffs also monazite in the bushveld tuff preserves additional information including a chronological fingerprint of the volcanic source 2 4 2 5 ga xenocrysts and the timing of low grade metamorphism 2 16 ga overgrowths the ca 2 16 ga low grade metamorphism identified in the bushveld basin is reminiscent of that widely recorded in the pilbara craton western australian lending support to arguments for a connection between the kaapvaal and pilbara cratons igneous and low grade metamorphic monazites are readily distinguished based on texture and chemistry our study demonstrates that monazite can be used to accurately date felsic tuffs offering a powerful tool for constraining depositional and metamorphic histories of precambrian sedimentary basins

rapid post seismic landslide evacuation boosted by dynamic river width how rivers evacuate large landslide deposits is crucial for predicting post seismic hazards a 2d hydro sedimentary model demonstrates that a narrowing river channel increases sediment transport which reduces export time by orders of magnitude

geophysical characteristics of the tornquist fan area northwest trans european suture zone indication of late carboniferous to early permian dextral transtension

seismic velocity structure across the fennoscandia sarmatia suture of the east european craton beneath the eurobridge profile through lithuania and belarus

the moho depth map of the european plate summary the european plate has a 4 5 gy long and complex tectonic history this is reflected in the present day large scale crustal structures a new digital moho depth map is compiled from more than 250 data sets of individual seismic profiles 3 d models obtained by body and surface waves receiver function results and maps of seismic and or gravity data compilations we have compiled the first digital high resolution map of the moho depth for the whole european plate extending from the mid atlantic ridge in the west to the ural mountains in the east and from the mediterranean sea in the south to the barents sea and spitsbergen in the arctic in the north in general three large domains within the european plate crust are visible the oldest archean and proterozoic crust has a thickness of 40 60 km the continental variscan and alpine crust has a thickness of 20 40 km and the youngest oceanic atlantic crust has a thickness of 10 20 km

random heterogeneity of the lithosphere across the trans european suture zone summary data from the passive teleseismic experiment tor across the trans european suture zone tesz which took place in 1996 1997 are used to study the random structure of the lithosphere ne of the tesz the baltic shield beneath southern sweden and beneath the north german danish basin p coda waves from deep teleseismic events give information on the small scale heterogeneity of the near receiver lithosphere on scales of one wavelength using an energy ux model the time and frequency behaviour of the p coda has been interpreted in terms of scattering qs and anelastic attenuation qi estimates of qs were obtained for the frequency range 0 5 3 hz for the north german danish basin and 0 5 7 hz for the baltic shield the two areas show a diierent scattering behaviour in denmark northern germany the scattering qs 125 200 is stronger than in southern sweden qs 275 500 and the peak of q 1 s occurs at higher frequencies ne of the tesz anelastic attenuation is negligible for the baltic shield whereas for the north german danish basin anelastic attenuation is present but still much weaker than scattering attenuation with a modi ed energy ux model for depth dependent scattering and assuming an exponential autocorrelation function the depth variation of correlation length a and rms velocity uctuation e can in principle be resolved for the baltic shield the scattering is mostly con ned to the crust with a 1k m ande 4 per cent the subcrustal lithosphere only shows weak uctuations the data from the north german danish basin cannot be explained by strong scattering within the crust only crustal parameters are a 5 10 km and e 8 per cent for the subcrustal lithosphere correlation lengths of 10 20 km and rms velocity uctuations of 6 8 per cent are found additional tests con rmed that the thick sedimentary cover in this area has no signi cant eiect on these results for the deeper structure correlation lengths for the sediments are smaller than 5 km and rms velocity uctuations e are 7 8 per cent

seismic velocities and q factors in the uppermost crust beneath the sveka profile in finland the sveka deep seismic sounding profile in central finland was shot in 1981 to study the crustal structure of the fennoscandian shield in the contact zone between the archaean and svecokarelian provinces apart from p and s waves well developed rayleigh surface waves r waves with periods of 0 5 2 0 s were recorded from all the shot points in the frequency band 0 5 2 5 hz the r waves were clearly observed on the entire 325 km long profile amplitudes of p s and r waves corrected for charge size were used to study the attenuation of waves and q factors from the records of body and r waves the distributions of seismic velocities and quality factors were determined using the dynamic ray tracing method 2 d modelling and the reflectivity method 1 d modelling in the 2 d model of the uppermost crust the p wave velocities vary from 5 8 5 9 km s at the top to 6 2 6 3 km s at a depth of 6 km the velocity ratio solvpvs varies with depth and distance from 1 67 to 1 74 reaching its maximum value of 1 8 2 0 in the uppermost 200 500 m and values of 1 76 1 80 in the uppermost 1 km the quality factors qp and qs vary in the uppermost 1 km from 20 to 120 reaching a higher value of 140 in the marginal zone of the archaean basement in the depth range of 1 2 km q values of 80 400 were found in the depth range 2 6 km q values of 300 800 were found for the svecokarelian province and 200 400 for the archaean the low values of vs and q in the uppermost 1 km are thought to be the result of rock fracturing the crack density was estimated for the uppermost crust along the profile for the sveka profile we found values of 0 35 0 54 in the uppermost 200 m 0 10 0 32 at a depth of 0 2 1 0 km and 0 1 for depths of 1 4 km the comparison of our seismic data with results of theoretical and laboratory investigations implies that the uppermost crustal rocks are saturated the zones of strong attenuation of r waves coincide with faults and schist zones which are well known from surface geology

major crustal features between the harz mountains and the baltic shield derived from receiver functions major crustal features between the harz mountains and the baltic shield derived from receiver functions

blockage of regional seismic waves by the teisseyre tornquist zone summary during the group of scientific experts technical test gsett second experiment 22 april 2 june 1991 several hundred seismic events were located in europe associating these events with the detecting stations altogether 28 european stations including seven arrays participated in the gsett 2 experiment clearly shows that the teisseyre tornquist zone ttz influences the propagation of regional seismic phases large explosions in the bay of gdansk for example were observed by the wellestablished scandinavian arrays norsar a 830 km and arcess a z 1650 km but not by the polish station ksp a 470km nor by the new highly sensitive geress array a 750 km both situated south west of the ttz for events in central europe with comparable magnitudes we observe a similar increase of the detection threshold at stations located north east of the ttz in scandinavia to explain these observations the wave propagation of pn and pg perpendicular to the ttz was modelled for a profile from the estonian russian border region to geress with gaussian beam seismograms published crustal and uppermost mantle models for poland and for europe were used as a starting point for developing a model of the ttz the observations cannot be explained only by a graben like crustal structure with a jump in moho depth from 30 km to 50 km to defocus the seismic energy the ttz as a structural anomaly between eastern and western europe must reach down into the upper mantle to a depth of at least about 200 km the proposed model has such a deep reaching root of the ttz

explosion generated short period surface wave dispersion and noise studies along linear seismic arrays in southern sweden summary the dispersion of short period fundamental mode rayleigh waves rg was measured along linear arrays on the baltic shield the data used is a selected set of 176 records along three refraction profiles in southern sweden the phase velocity determined in the 0 2 3 5 hz band could be grouped into a number of dispersion regions each regional dispersion showed a high internal consistency and the slowness as function of frequency was almost linear in the 1 3 hz band linear regression was used to separate the effects of the medium from the experimental uncertainties systematic studies of the noise to signal ratio showed that the standard deviation of the dispersion within each region and the above frequency band essentially reflected the lateral heterogeneities from the dispersion shear velocity models were inverted down to about 2 3 km in one case down to 6 km the s wave velocity was weakly constrained to a non decreasing function of depth with decreasing gradient the p wave velocity was constrained using recent results on poisson s constant ranging from 0 28 to 0 25 in the 0 2 km interval the density was constrained using geological knowledge of the area using these constraints the s wave velocity increased rapidly with depth in the first few hundred metres of the crust the models could be naturally grouped into three sets with similar character in close agreement with the large scale surface geology the highest velocities were found in the east in the smiland varmland granitic belt and the smallest in the northwest in the sveconorwegian crust

three dimensional crustal structure beneath the tor array and effects on teleseismic wavefronts abstract the temporary seismic station array tor was designed to study the lithosphere asthenosphere system across the northwestern part of the trans european suture zone tesz by teleseismic tomography teleseismic wavefronts when propagating through complex crustal structure undergo severe distortion that may result in travel time residual anomalies of significant amplitude the inversion of teleseismic travel time residuals for deep structures without accounting for such crustal related anomalies may erroneously map these travel time anomalies into features at greater depth in this study we apply a three dimensional 3 d technique to estimate effects of a priori known 3 d crustal structure on travel times of teleseismic waves observed at the tor seismic array across the tesz to correct for these effects in future tomographic studies a uniform 3 d crustal model is developed by use of published two dimensional crustal models from previous active seismic surveys the parameterization of this 3 d crustal model is designed to adequately represent those crustal structures that mostly influence the propagation of teleseismic wavefronts the 3 d model includes lateral variation in velocity structure moho topography and large and deep sedimentary basins the teleseismic forward problem for this local 3 d model is solved by calculation of travel times to the base of the model using a standard whole earth model and by subsequent propagation of spherical wavefronts using finite difference methods travel time calculations for an event near japan reveal significant lateral variations in the range between 0 3 s and 0 5 s due to crustal structures being able to obtain the full travel time field at the surface of the model has the additional advantage of improving the identification and timing of seismic phases observed at the tor seismic array

q along the fennolora profile summary the fennoscandian long range project fennolora recorded refraction data on a profile from northern norway through sweden to the baltic sea the data have been used to interpret complex crust and upper mantle structure to 450 km depth and the data are unique in scandinavia for their extension and quality in this study crustal q has been determined for p waves along the profile using the spectral ratio method q was found to be frequency dependent of the form q q0fm where q0 and m are constants and f is the frequency in order to simplify the presentation and interpretation of the results and to allow comparison to other studies q was also determined assuming independence of frequency q varied by up to a factor of 3 along the profile with generally increasing values going from north to south this might correlate with more complex structure at the northern segment than at the southern segment average crustal q for the whole profile using all data was q 29f0 96 and the corresponding constant q was 460 since most of the energy in the spectra was from 3 to 30 hz it seems that the frequency independent q is comparable to q f at the average frequency at 16 hz q f 415 the sensitivity of q with depth was investigated using pairs of stations with average distance to shot points of 50 150 and 250 km the average frequency independent q values thus obtained were 430 470 and 480 respectively with a somewhat larger variation for the frequency dependent q values however using the present method and data set there is no indication of significant variation of crustal q with depth this is in contrast to many coda q studies which give increased q with depth

thermal properties of the crust and the lithosphere asthenosphere boundary in the area of poland from the heat flow variability and seismic data high resolution 3d seismic p wave velocity model of poland grad et al tectonophysics 666 188 210 2016 and corrected for paleoclimate heat flow map majorowicz and wybraniec int j earth sci 100 4 881 887 2011 gridded to a common mesh are used together with four independent thermal models of the crust and upper mantle to calculate heat flow variation with depth and geotherms heat flow at moho depth are calculated and mapped and both confirm large variability with an elevated mantle heat flow circa 30 40 mw m2 in the paleozoic platform which is some 10 20 mw m2 higher than moho heat flow in the north eastern and south eastern poland which belong to a variety of tectonic terranes the oldest precambrian craton younger cadomian trans european suture zone carpathians temperatures calculated for the crust show consistent pattern higher temperatures beneath the paleozoic platform and lower temperatures beneath the precambrian and cadomian units at 10 km depth this difference is about 150 c about 300 c at 20 km depth and about 400 c at 50 60 km assuming the calculated isotherm 580 c as curie temperature the magnetic crust thickness was determined as 5 10 km only beneath the polish basin circa 20 km in carpathians circa 30 km in sudetes and 35 40 km beneath the precambrian and cadomian units such a thick magnetic crust results from a great depth of curie temperature thick crystalline crust and thin sediments mantle heat flow variability is mainly correlating with measured surface heat flow and influences geotherms calculated thermal lab depth follows patterns of heat flow and moho heat flow variability through poland with thinnest lithosphere in the high surface heat flow and high mantle heat flow areas comparison of this thermal lab depth estimates with seismic data based lab depth shows general coincidences when precambrian craton vs paleozoic platform are considered along the p4 seismic experiment data model circa 190 km depth vs some 90 km depth respectively however significant differences exist in many areas and especially for the se poland when compared with map for the whole of poland compiled from other seismic reported data

crustal structure variation from the precambrian to palaeozoic platforms in europe imaged by the inversion of teleseismic receiver functions project tor the tor experiment teleseismic tomography tornquist carried out in winter 1996 97 across the trans european suture zone tesz in germany denmark and sweden has collected new data to investigate the transition zone between precambrian and palaeozoic europe in this study seismograms of teleseismic earthquakes recorded by the broad band tor stations have been used to calculate the receiver functions the time domain inversion method has been applied to the receiver functions to compute s wave velocities in the crust and uppermost mantle beneath each station the results of inversion down to 60 km depth provide new independent information about the distribution of s wave velocity in this area beneath the swedish stations on baltica the thickness of the crust varies from about 45 to 50 km with mostly gradually increasing s wave velocity and no sharp discontinuities while for danish and german stations the crust is thinner 29 38 km with a sharp moho discontinuity a very distinct s wave low velocity layer was found at depth of 8 16 km in the upper crust of baltica supported by the results of refraction deep seismic sounding experiments using both p and s waves the map of v p v s ratio beneath the c 1000 km long tor profile was obtained using the v p velocity model from previous investigations the values of v p v s 1 73 were found in the uppermost crust of baltica and upper avalonian crust the low velocity layer in the upper crust of baltica is characterized by high value of v p v s 1 85 relatively low s wave velocities are observed in the lower crust of variscides v p v s 1 79 baltica v p v s 1 83 and avalonia v p v s 1 91 in the uppermost mantle v p v s values are 1 77 1 79 and 1 82 respectively

p and s wave velocity model of the southwestern margin of the precambrian east european craton polonaise 97 profile p3 the large scale seismic experiment polonaise 97 investigated the seismic structure of the crust and the uppermost mantle in the polish region of the trans european suture zone this paper covers the interpretation of seismic data along the 300 km long p3 profile which is located in the precambrian east european craton eec parallel to the teisseyre tornquist zone the recordings were of high quality with seismic energy detectable out to 300 km ovsets the crustal model developed by two dimensional raytracing forward modelling and waveform analysis is characterized by a subhorizontal uniform structure although the boundaries of several large basement features are crossed the crystalline crust consists of three parts the upper middle and lower crust with p wave velocities of 6 1 6 4 km s 6 55 6 7 km s and 7 05 7 15 km s respectively the p m p wave can usually be correlated at distances beginning at about 100 km but it has variable reflection character moho depth increases from 38 km at the nw end of the profile to 44 km at the se end the p n velocity of 8 05 8 1 km s is less than that previously found in neighbouring areas of the eec the v p v s ratio was determined separately for the upper middle and lower crust to be 1 67 and 1 77 respectively following the p n wave another phase with an apparent velocity of about 8 3 km si s interpreted as a weak reflection from a low contrast discontinuity in the uppermost mantle 1999 elsevier science b v all rights reserved

sharp contrast in lithospheric structure across the sorgenfrei tornquist zone as inferred by rayleigh wave analysis of tor1 project data abstract this work is a part of the tor1 project 1996 1997 and is devoted to determining the lithospheric structure across the sorgenfrei tornquist zone in northern europe for the first time in europe a very dense seismic broadband array has offered the possibility of determining very sharp lateral variations in the structure of the lithosphere at small scales using surface wave analysis we measure phase velocities for rayleigh waves with periods ranging between 10 and 100 s both within arrays with apertures of 40 50 km small compared to the wavelength and along long profiles of at least 100 km dispersion curves are then inverted and shear wave velocity models down to the depth of 200 km are proposed we show that the sorgenfrei tornquist zone is a major tectonic feature within the whole lithosphere north east of this feature in sweden beneath the baltic shield no lithosphere asthenosphere boundary is observed to exist to depths of 200 km south west of the sorgenfrei tornquist zone beneath denmark we find a lithospheric thickness of 120 20 km the transition across the sorgenfrei tornquist zone is sharp and determined to be very steeply dipping to the south west we also demonstrate the existence of a sharp discontinuity between the lithospheres beneath denmark 120 20 km thick and beneath germany characterized by thicknesses of 50 10 km in the northernmost part and 100 20 km in the southwest this discontinuity is most likely related to the trans european fault at the surface

a new absolute arrival time data set for europe summary the main aim of this study is to create a data set of accurate absolute arrival times for stations in europe which do not report to the international seismological centre isc waveforms were obtained from data centres and temporary experiments and a semi automatic picking method was applied to determine absolute arrival times for p and s phases 85 000 arrival times were picked whose distribution of residuals shows generally low standard deviations on the order of 0 5 0 7 s furthermore mean teleseismic station residuals reflect the properties of the underlying crust and uppermost mantle comparison to isc data for matching event stationphase combinations also confirms the good quality of the new absolute arrival time picks most importantly this data set complements the isc data as it fills regional data coverage gaps in europe

travel time tomography of the european mediterranean mantle down to 1400 km abstract the 3 d p wave velocity structure of the mantle below europe the mediterranean region and a part of asia minor is investigated this study is a considerable extension of an earlier tomographic experiment that was limited to imaging upper mantle structure only here the earth s volume under study encompasses the mantle to a depth of 1400 km and we increase the number of international seismological centre isc data for inversion by a factor of four by taking more years of observation and by including data from teleseismic events the most important departure from the earlier study is that we do not use the jeffreys bullen model as a reference model but an improved radially symmetric velocity model the pm2 model which is appropriate for the european mediterranean mantle our inversion procedure consists of two steps first the radial model pm2 is determined from the isc delay times by a nonlinear trial and error inversion of the data as opposed to the jeffreys bullen model the new reference model has a high velocity lithosphere a low velocity zone and seismic discontinuities at depths of 400 and 670 km next the isc data are corrected for effects related to the change in reference model and inverted for 3 d heterogeneity relative to the pm2 model we follow this two step approach to attain a better linearizable tomographic problem in which ray paths computed in the pm2 model provide a better approximation of the actual ray paths than those computed from the jeffreys bullen model hence the two step scheme leads to a more credible application of fermat s principle in linearizing the tomographic equations inversion results for the 3 d heterogeneity are computed for both the uncorrected isc data and for the pm2 data the data fit obtained in the two step approach is slightly better than in the inversion of isc data using the jeffreys bullen reference model a comparison of the tomographic results demonstrates that the pm2 data inversion is to be preferred to assess the spatial resolution an analysis is given of hit count patterns sampling of the mantle by ray paths and results of sensitivity tests with 3 d synthetic velocity models the spatial resolution obtained varies with position in the mantle and is studied both in map view and in cross section in the well sampled regions of the mantle the spatial resolution for larger scale structure can qualitatively be denoted as reasonable to good and at least sufficient to allow interpretation of larger scale anomalies a comparison is made of the results of this study with independent models of s velocity heterogeneity obtained in a number of investigations and with a prediction of the seismic velocity structure of the mantle computed from tectonic reconstructions of the mediterranean region in the context of this comparison interpretations of large scale positive anomalies found in the mediterranean upper mantle in terms of subducted lithosphere are given specifically addressed are subduction below southern spain below the western mediterranean and italy and below the aegean in the last region a slab anomaly is mapped down to depths of 800 km

a preliminary interpretation of s wave traveltimes from fennolora data abstract the fennolora profile runs across the baltic shield in a north south direction this interpretation presents a preliminary velocity distribution of the crust based on traveltimes from the vertical components of s waves the seismogram sections are usually filtered with a bandpass filter from 1 to 6 hz in a few cases the s wave frequency was considerably higher only quite clear phases are used and the velocity curves are made as simple as possible in the upper part of the crust the velocities are between 3 2 and 3 65 km s in several seismogram sections there are low velocity zones at a depth of around 5 to 10 km with a velocity of approximately 3 5 km s in the lower part of the crust the velocities are between 3 7 and 4 2 km s the moho depth varies from 37 km to 49 5 km