lithospheric structure in the area of crete constrained by receiver functions and dispersion analysis of rayleigh phase velocities summary we present a case study of lithospheric structure in the forearc of a retreating subduction zone for the hellenic arc lateral structural variations along the arc beneath the island of crete are jointly investigated by receiver functions and rayleigh phase velocities data from temporary short period networks amend previous results from broad band stations by broadening the frequency range available for phase velocity determination and increasing the spatial coverage of receiver function profiles both receiver functions and dispersion analysis reveal distinct structural differences between western and central crete western crete is characterized by nearly constant s velocities of 3 72 3 75 km s 1 from 10 km depth down to a depth of 50 km and no distinct continental moho signal meanwhile central crete shows lower s velocities equal to 3 3 km s 1 in the crust between 10 and 20 km depth which are followed by the aegean moho in about 30 km depth and a mantle wedge with an s velocity of 4 35 km s 1 both methods lead to an average depth of 55 km for the subducted oceanic african moho beneath crete this means that the slab is separated from the aegean crust by a mantle wedge beneath central crete while beneath western crete the corresponding depth region is characterized by crustal velocities this thickened crust in the forearc might be formed by crustal material of the aegean plate dragged down with the subducting african lithosphere furthermore rocks extruded from a melange circulating in a subduction channel might accumulate between a depth of 20 and 50 km and contain low velocity material e g in the form of serpentinized aegean mantle in addition the lateral extent of a prominent negative phase observed around 4 s differential time in receiver functions from western crete is mapped this phase might point to low velocity material around 30 km depth which could be extruded from a subduction channel an important property of the forearc found in this study is its strong lateral heterogeneity

imaging alpine crust using ambient noise wave equation tomography we present an improved crustal vs model and moho depth map using ambient noise wave equation tomography the so called ambient noise wave equation tomography is a method to invert seismic ambient noise phase dispersion data based on elastic waveform simulation which accounts for 3 d and finite frequency effects we use cross correlations of up to four years of continuous vertical component ambient seismic noise recordings from 304 high quality broadband stations in the alpine region we use model lsp eucrust1 0 obtained from traditional ambient noise tomography as initial model and we iteratively improve the initial model by minimizing frequency dependent phase traveltime differences between the observed and synthetic waveforms of rayleigh waves in the period range 10 50 s we obtain the final model after 15 iterations with 65 total misfit reduction compared to the initial model at crustal depth the final model significantly enhances the amplitudes and adjusts the shapes of velocity anomalies at moho and upper mantle depth the final model corrects an obvious systematic velocity shift of the initial model the resulting iso velocity moho map confirms a moho step along the external side of the external crystalline massifs of the northwestern alps and reveals underplated gabbroic plutons in the lower most crust of the central and eastern alps ambient noise wave equation tomography turns out to be a useful tool to refine shear wave velocity models obtained by traditional ambient noise tomography based on ray theory

global upper mantle structure from finite frequency surface wave tomography 1 we report global shear wave velocity structure and radial anisotropy in the upper mantle obtained using finite frequency surface wave tomography based upon complete three dimensional born sensitivity kernels because wavefront healing effects are properly taken into account finite frequency surface wave tomography improves the resolution of small scale mantle heterogeneities especially for deep anomalies that are constrained by the longest period surface waves in our finite frequency model ffsw1 the globally averaged radial anisotropy shows a transition from positive sh sv to negative anisotropy sv sh at about 220 km consistent with a change in the dominant mantle circulation pattern from predominantly horizontal flow at shallow depths to vertical flow at greater depths the radial anisotropy beneath cratons and the old pacific plate agrees well with previous studies however our model exhibits a strong negative radial anisotropy at depths greater than 120 km beneath mid ocean ridges a feature that is not present in previous upper mantle models more interestingly the depth extent of the ridge anomalies is distinctly different beneath fast and slow spreading centers anomalies beneath fast spreading centers are stronger but the strength decreases rapidly below 250 km in contrast beneath slow spreading centers such as the northern mid atlantic ridge and the red sea anomalies extend down at least to the top of the transition zone the different depth extent of the ridge anomalies suggests that the primary driving force of slow spreading seafloor may be different from that of fast spreading seafloor and that active upwelling beneath slow spreading ridges may play a major role in the opening of the seafloor

post depositional tectonic modification of vms deposits in iberia and its economic significance the original stratigraphic relationships and structure of vms deposits are commonly obscured by deformation this can also affect their economic significance as shown by several iberian pyrite belt ipb sw iberia examples the contrasting rheologic properties of the different lithologies present in an orebody massive sulphide feeder stockwork alteration envelope volcanic and sedimentary rocks play a major role in determining its overall behaviour variscan thin skinned tectonics led to stacking of the massive pyrite and stockwork bodies in duplex structures resulting in local thickening and increased tonnage of minable mineralization furthermore differential mechanical behaviour of the different sulphide minerals localised the detachments along relatively ductile sulphide rich bands the result was a geochemical and mineralogical reorganisation of most deposits which now consist of barren massive pyrite horses bounded by base metal rich ductile shear zones metal redistribution was enhanced by mobilisation of the base metal sulphides from the initially impoverished massive pyrite through pressure solution processes to tensional fissures within the already ductile shear zones in nw iberia vms deposits were also strongly overprinted by the variscan deformation during emplacement of the cabo ortegal and ordenes allochthonous nappe complexes but no stacking of the orebodies was produced original contacts were transposed and the orebodies their feeder zones and the country rock acquired pronounced laminar geometry in lower grade rocks greenschist facies cabo ortegal complex solution transfer mechanisms are common in pyrite which remains in the brittle domain while chalcopyrite shows ductile behaviour in higher grade rocks amphibolite facies ordenes complex metamorphic recrystallisation overprints earlier deformation textures the contrasting behaviour of the ipb and nw iberian deposits is explained by key factors that affect their final geometry composition and economics such as pre deformation structure size and mineralogical composition of the orebody and associated lithologies temperature crustal level deviatoric stress and availability of a fluid phase during deformation and the style and rate of deformation

surface wave tomography of the western united states from ambient seismic noise rayleigh and love wave phase velocity maps summary we present the results of rayleigh wave and love wave phase velocity tomography in the western united states using ambient seismic noise observed at over 250 broad band stations from the earthscope usarray transportable array and regional networks all available threecomponent time series for the 12 month span between 2005 november 1 and 2006 october 31 have been cross correlated to yield estimated empirical rayleigh and love wave green s functions the love wave signals were observed with higher average signal to noise ratio snr than rayleigh wave signals and hence cannot be fully explained by the scattering of rayleigh waves phase velocity dispersion curves for both rayleigh and love waves between 5 and 40 speriod were measured for each interstation path by applying frequency time analysis the average uncertainty and systematic bias of the measurements are estimated using a method based on analysing thousands of nearly linearly aligned station triplets we find that empirical green s functions can be estimated accurately from the negative time derivative of the symmetric component ambient noise cross correlation without explicit knowledge of the source distribution the average traveltime uncertainty is less than 1 s at periods shorter than 24 s we present rayleigh and love wave phase speed maps at periods of 8 12 16 and 20 s the maps show clear correlations with major geological structures and qualitative agreement with previous results based on rayleigh wave group speeds

reflection and transmission of surface waves at a vertical discontinuity and imaging of lateral heterogeneity using reflected fundamental rayleigh waves we present a technique for the determination of approximate reflection and transmission coefficients of surface wave modes for a vertical plane discontinuity that is simple to use it is applied to different models of lateral heterogeneity furthermore a method for the localization of lateral heterogeneity using the coda of the fundamental rayleigh mode is proposed in particular the frequency content of surface waves enables the investigation of the lower crust and the uppermost mantle lateral changes of the s wave velocity density and p wave velocity lead to the formation of the coda of the fundamental rayleigh mode that contains delayed surface waves that reach the recording station indirectly the complicated structure of the coda makes it impossible to identify reflected surface waves visually using a small number of recordings only coda waveforms of a large number of source station pairs are inverted simultaneously for experimental reflection coefficients the method is successfully tested using an ultrasonic model experiment finally it is applied to central europe and especially to the tornquist zone tz mainly using records of the german regional seismological network grsn the resulting reflection coefficients depend on frequency and give an image of the location of reflectors

the genesis and metamorphism of the arinteiro bama cu deposits santiago de compostela northwestern spain disseminated pyrrhotite chalcopyrite host rocks are ophiolitic metabasites protoliths of the ore horizon were hydrothermally altered mafic rocks with silica and sulfides large scale stockwork alteration system the predominant garnet gedrite biotite staurolite assemblages of the ore horizon are products of polyphase metamorphism which was isochemical with respect to nonvolatile components modified journal abstract

landslide susceptibility revealed by lidar imagery and historical records seattle washington abstract light detection and ranging lidar data were used to visually map landslides headscarps and denuded slopes in seattle washington four times more landslides were mapped than by previous efforts that used aerial photographs the mapped landforms landslides headscarps and denuded slopes were created by many individual landslides the spatial distribution of mapped landforms and 1308 historical landslides show that historical landslide activity has been concentrated on the mapped landforms and that most of the landslide activity that created the landforms was prehistoric thus the spatial densities of historical landslides on the landforms provide approximations of the landforms relative susceptibilities to future landsliding historical landslide characteristics appear to be closely related to landform type so relative susceptibilities were determined for landslides with various characteristics no strong relations were identified between stratigraphy and landslide occurrence however landslide characteristics and slope morphology appear to be related to stratigraphic conditions human activity is responsible for causing about 80 of historical seattle landslides the distribution of mapped landforms and human caused landslides suggests the probable characteristics of future human caused landslides on each of the landforms the distribution of mapped landforms and historical landslides suggests that erosion of slope toes by surface water has been a necessary condition for causing seattle landslides human activity has largely arrested this erosion which implies that landslide activity will decrease with time as hillsides naturally stabilize however evaluation of glacial age analogs of areas of recent slope toe erosion suggests that landslide activity in seattle will continue for the foreseeable future

a 3 d model of the crust and uppermost mantle beneath the central and western us by joint inversion of receiver functions and surface wave dispersion 1 rayleigh wave phase velocity maps from ambient noise and earthquake data are inverted jointly with receiver functions observed at 828 stations from the usarray transportable array west of 100 w longitude for data recorded in the years 2005 through 2010 to produce a 3 d model of shear wave speeds beneath the central and western us to a depth of 150 km eikonal tomography is applied to ambient noise data to produce about 300 000 rayleigh wave phase speed curves and helmholtz tomography is applied to data following 1550 ms 5 0 earthquakes so that rayleigh wave dispersion maps are constructed from 8 to 80 s period with associated uncertainties across the region harmonic stripping generates back azimuth independent receiver functions with uncertainty estimates for each of the stations a nonlinear bayesian monte carlo method is used to estimate a distribution of shear wave speed vs models beneath each station by jointly interpreting surface wave dispersion and receiver functions and their uncertainties the assimilation of receiver functions improves the vertical resolution of the model by reducing the range of estimated moho depths improving the determination of the shear velocity jump across moho and improving the resolution of the depth of anomalies in the uppermost mantle a great variety of geological and tectonic features are revealed in the 3 d model that form the basis for future detailed local to regional scale analysis and interpretation

automated landslide mapping using spectral analysis and high resolution topographic data puget sound lowlands washington and portland hills oregon abstract landslide inventory maps are necessary for assessing landslide hazards and addressing the role slope stability plays in landscape evolution over geologic timescales however landslide inventory maps produced with traditional methods aerial photograph interpretation topographic map analysis and field inspection are often subjective and incomplete the increasing availability of high resolution topographic data acquired via airborne light detection and ranging lidar over broad swaths of terrain invites new automated landslide mapping procedures we present two methods of spectral analysis that utilize lidar derived digital elevation models of the puget sound lowlands washington and the tualatin mountains oregon to quantify and automatically map the topographic signatures of deep seated landslides power spectra produced using the two dimensional discrete fourier transform and the two dimensional continuous wavelet transform identify the characteristic spatial frequencies of deep seated landslide morphologic features such as hummocky topography scarps and displaced blocks of material spatial patterns in the amount of spectral power concentrated in these characteristic frequency bands highlight past slope instabilities and allow the delineation of landslide terrain when calibrated by comparison with detailed independently compiled landslide inventory maps our algorithms correctly classify an average of 82 of the terrain in our five study areas spectral analysis also allows the creation of dominant wavelength maps which prove useful in analyzing meter scale topographic expressions of landslide mechanics past landslide activity and landslide modifying geomorphic processes these results suggest that our automated landslide mapping methods can create accurate landslide maps and serve as effective objective and efficient tools for digital terrain analysis

high and low resolution images of the earth s mantle implications of different approaches to tomographic modeling recently published images of the earth s mantle are characterized by a nominal resolution much higher than that used in previous studies where substantially different techniques were employed the agreement between such high resolution and low resolution images often seems very poor in an attempt to determine the reason for this discrepancy we analyze how the choice of inversion algorithm exact or iterative regularization norm or roughness minimization and parameterization spherical harmonics up to a variable degree blocks affects a tomographic model we also investigate the effects of the varying density of the data coverage on the final solution in our experiments we employ two seismic data sets rayleigh wave phase velocity at 75 s period and p wave travel times we construct a new model of p velocity in the mantle bdp98 based on the international seismological center bulletins 1964 1992 we use our findings in an evaluation of recent mantle models including our own focusing on similarities and discrepancies between models of different nominal resolution in all the models the long wavelength component is the most stable however consistent high resolution details probably corresponding to features of the real earth are also seen in general we conclude that most of the differences between existing tomographic models derive from the arbitrary choices made in the process of defining and solving the inverse problem rather than from actual errors or approximations

automated multimode phase speed measurements for high resolution regional scale tomography application to north america summary a fully automated method for obtaining multimode phase speed measurements from a single seismogram has been developed and applied to a large data set of three component longperiod seismograms in north america constructing high resolution phase speed maps on a continental scale the method of our phase speed estimation is based on a fully non linear waveform inversion by yoshizawa kennett working with a global search method the neighbourhood algorithm the entire process of waveform fitting and the evaluation of the estimated phase speed have been fully automated employing several empirical quantitative measures assessing the quality of waveform fit and the relative contributions of each mode in a chosen time window the measured phase speed data undergo automatic screening for quality control comprising the threshold evaluation of their reliability and outlier detection and removal this new automated method has been applied to a large data set recorded at north american stations including the latest transportable stations of usarray using long period three component seismograms recorded during the past eight years we have successfully retrieved large numbers of regional surface wave paths including over 20000 paths for the fundamental mode rayleigh waves over a wide range of frequencies and over 10000 paths for the higher mode rayleigh as well as the fundamental mode love waves the consistentresultsoftheautomatedmeasurementproceduresuggestthatthemethodworkswell at regional distances allowing us to perform a high resolution mapping of multimode phase speeds in north america the results of the automated waveform analysis also indicate some intrinsic limitations in the higher mode phase speed measurements from a single seismogram particularly in the short period range mainly due to the overlapping of higher mode arrivals as well as coupling between mode branches despite such an innate difficulty in the higher mode dispersion measurements the automated method allows us to construct reliable multimode phase speed maps the current data set of ray paths is significantly biased towards the western half of north america resulting in non uniform horizontal resolution across the continent this issue will be resolved by the future migration of the usarray stations to cover the central and eastern united states the new automated method can be a useful tool for high resolution mapping of regional 3 d shear wave structure including possible anisotropy

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

crustal and uppermost mantle structure in southern africa revealed from ambient noise and teleseismic tomography summary rayleigh wave phase velocity maps in southern africa are obtained at periods from 6 to 40 s using seismic ambient noise tomography applied to data from the southern africa seismic experiment sase deployed between 1997 and 1999 these phase velocity maps are combined with those from 45 to 143 s period which were determined previously using a two planewave method by li burke in the period range of overlap 25 40 s the ambient noise and two plane wave methods yield similar phase velocity maps dispersion curves from 6 to 143 s period were used to estimate the 3 d shear wave structure of the crust and uppermost mantle on an 1 1 grid beneath southern africa to a depth of about 100 km average shear wave velocity in the crust is found to vary from 3 6 km s 1 at 0 10 km depths to 3 86 km s 1 from 20 to 40 km and velocity anomalies in these layers correlate with known tectonic features shear wave velocity in the lower crust is on average low in the kaapvaal and zimbabwe cratons and higher in the surrounding proterozoic terranes such as the limpopo and the namaquanatal belts which suggests that the lower crust underlying the archean cratons is probably less mafic than beneath the proterozoic terranes crustal thickness estimates agree well with a previous receiver function study of nair et al archean crust is relatively thin and light and underlain by a fast uppermost mantle whereas the proterozoic crust is thick and dense with a slower underlying mantle these observations are consistent with the southern african archean cratons having been formed by the accretion of island arcs with the convective removal of the dense lower crust if the foundering process became less vigorous in arc environments during the proterozoic

crustal and uppermost mantle structure of southern norway results from surface wave analysis of ambient seismic noise and earthquake data summary we use ambient seismic noise and earthquake recordings on a temporary regional network in southern norway to produce rayleigh and love wave phase velocity maps from 3 to 67 s period local dispersion curves are then jointly inverted for a 3 d shear wave velocity model of the region we perform a two step inversion approach first a direct search monte carlo algorithm is applied to find best fitting isotropic velocity depth profiles those profiles are then used as initial models for a linearised inversion which takes into account radial anisotropy in the shear wave structure results reveal crustal as well as uppermost mantle structures in the studied region velocity anomalies in the upper crust are rather small in amplitude and can in most parts be related to surface geology in terms of rock densities old tectonic units like the oslo graben 300 240 ma and the caledonian nappes 440 410 ma are clearly imaged furthermore we find clear indications for localized crustal anisotropy of about 3 per cent despite generally poor resolution of interface depths in surface wave inversion we find lateral variation of crustal thickness in agreement with previous studies we are able to confirm and locate the transition from a slow lithospheric upper mantle underneath southern norway to a fast shield like mantle towards sweden

influence of the seismic noise characteristics on noise correlations in the baltic shield it has recently been shown that correlations of seismic noise can contain significant information about the green s function along the station profile using an array of 38 temporary broad band stations located in finland between 1998 september and 1999 march we study the resulting 703 noise correlations to understand how they are influenced by the directivity of the noise field the latter information is obtained through f k analysis of data from two permanent seismic arrays in germany and norway and from a subset of stations of the array in finland both types of analysis confirm that the characteristics of the seismic noise is strongly frequency dependent at low frequencies 0 02 0 04 hz we observe diffuse noise and or randomly distributed sources in contrast the noise is strongly direction dependent and not fully diffuse in the intermediate period ranges 0 04 0 25 hz which correspond to the first and second microseismic peak created at the irish and scottish coast and the western coast of norway in this frequency interval the noise is sufficiently close to a plane wave to introduce systematic errors in group velocities for station pairs which are not parallel to the direction of the dominant incident noise phase velocities calculated by slant stack over many traces are however correct independently of profile direction in the high frequency band 0 25 1 0 hz the situation is a mix between the low frequency and the intermediate frequency cases average phase velocities and individual group velocities from well oriented profiles are in excellent agreement with results from rayleigh wave studies of the area

arrival angles of teleseismic fundamental mode rayleigh waves across the alparray the dense alparray network allows studying seismic wave propagation with high spatial resolution here we introduce an array approach to measure arrival angles of teleseismic rayleigh waves the approach combines the advantages of phase correlation as in the two station method with array beamforming to obtain the phase velocity vector 20 earthquakes from the first two years of the alparray project are selected and spatial patterns of arrival angle deviations across the alparray are shown in maps depending on period and earthquake location the cause of these intriguing spatial patterns is discussed a simple wave propagation modelling example using an isolated anomaly and a gaussian beam solution suggests that much of the complexity can be explained as a result of wave interference after passing a structural anomaly along the wave paths this indicates that arrival angle information constitutes useful additional information on the earth structure beyond what is currently used in inversions

two receiver measurements of phase velocity cross validation of ambient noise and earthquake based observations phase velocities derived from ambient noise cross correlation are compared with phase velocities calculated from cross correlations of waveform recordings of teleseismic earthquakes whose epicentres are approximately on the station station great circle the comparison is conducted both for rayleigh and love waves using over 1000 station pairs in central europe we describe in detail our signal processing method which allows for automated processing of large amounts of data ambient noise data are collected in the 5 80 s period range whereas teleseismic data are available between about 8 and 250 s resulting in a broad common period range between 8 and 80 s at intermediate periods around 30 s and for shorter interstation distances phase velocities measured from ambient noise are on average between 0 5 per cent and 1 5 per cent lower than those observed via the earthquake based method this discrepancy is small compared to typical phase velocity heterogeneities 10 per cent peak to peak or more observed in this period range we nevertheless conduct a suite of synthetic tests to evaluate whether known biases in ambient noise cross correlation measurements could account for this discrepancy we specifically evaluate the effects of heterogeneities in source distribution of azimuthal anisotropy in surface wave velocity and of the presence of near field rather than far field only sources of seismic noise we find that these effects can be quite important comparing individual station pairs the systematic discrepancy is presumably due to a combination of factors related to differences in sensitivity of earthquake versus noise data to lateral heterogeneity the data sets from both methods are used to create some preliminary tomographic maps that are characterized by velocity heterogeneities of similar amplitude and pattern confirming the overall agreement between the two measurement methods

application of wavelet analysis to the study of spatial pattern of morphotectonic lineaments in digital terrain models a case study tectonic faults are often associated with characteristic geomorphological features such as linear valleys ridgelines and slope breaks that can be identified as lineaments in remotely sensed images or digital terrain models lineaments of tectonic origin are often characterised by periodicity and characteristic spatial pattern unlike traditional methods of autocorrelation variogram lineament density and fourier analysis wavelet analysis is capable of capturing and describing both periodicity and spatial pattern of lineaments in this paper a case study is shown for the application of wavelet analysis to morphotectonic lineament investigation results of wavelet analysis are compared to traditional methods although this study involves dem derived morphological lineaments the presented wavelet analysis can be also used for lineaments derived from remotely sensed images these results hold for this case study and provide a good assessment of the relative abilities of wavelet analysis but it remains to be seen how effective it is for other data sources areas and geological terrain

a crustal model for the eastern alps region and a new moho map in southeastern europe in the last two decades south central europe and the eastern alps have been widely explored by many seismic refraction experiments e g celebration 2000 alp 2002 sudetes 2003 although quite detailed images are available along linear profiles a comprehensive three dimensional crustal model of the region is still missing this limitation makes this region a weak spot in continental wide comprehensive representations of crustal structure to improve on this situation we select and collect 37 published active source seismic lines in this region after geo referencing each line we sample them along vertical profiles every 50 km or less along the line and derive p wave velocities in a stack of homogeneous layers separated by discontinuities depth of crystalline basement top of lower crust and moho we finally merge the information using geostatistical methods and infer s wave velocity and density using empirical scaling relations we present here the resulting crustal model for a region encompassing the eastern alps dinarides pannonian basin western carpathians and bohemian massif covering the region within 45 circ text 51 circ hbox n and 11 circ text 22 circ hbox e with a resolution of 0 2 circ times 0 2 circ we are also able to extend and update the map of moho depth in a wider region within 35 circ text 51 circ hbox n and 12 circ text 45 circ hbox e gathering moho values from the collected seismic lines other published dataset and using the european plate reference epcrust as a background all the digitized profiles and the resulting model are available online

3 d shear wave velocity model of the lithosphere below the sardinia corsica continental block based on rayleigh wave phase velocities rayleigh wave dispersion curves from both ambient noise and teleseismic events allow us to provide the first high resolution 3 d shear wave velocity vs model of the crust and upper mantle below the sardinia corsica microplate an important continental block for understanding the evolution of the central western mediterranean for a wide range of periods from 3 to 30 s the phase velocities of the study area are systematically higher than those measured within the italian peninsula in agreement with a colder geotherm relative and absolute variations in the vs allow us to detect a very heterogeneous upper crust down to 8 km as opposed to a relatively homogeneous middle and lower crust the isosurface at 4 1 km s 1 is consistent with a rather flat moho at a depth of 28 0 1 8 km 2 the lithospheric mantle is relatively cold and we constrain the thermal lithosphere asthenosphere boundary at 100 km we find our estimate consistent with a continental geotherm based on a surface heat flow of 60 mw m 2 our results suggest that most of the lithosphere endured the complex history of deformation experienced by the study area and imply in general that deep tectonic processes do not easily destabilize the deeper portion of the continental lithosphere despite leaving a clear surface signature

surface wave array tomography in se tibet from ambient seismic noise and two station analysis ii crustal and upper mantle structure summary we determine the 3 d shear wave speed variations in the crust and upper mantle in the southeastern borderland of the tibetan plateau sw china with data from 25 temporary broad band stations and one permanent station interstation rayleigh wave phase velocity dispersion curves were obtained at periods from 10 to 50 s from empirical green s function egf derived from ambient noise interferometry and from 20 to 150 s from traditional two station ts analysis here we use these measurements to construct phase velocity maps from 10 to 150 s using the average interstation dispersion from the egf and ts methods between 20 and 50 s and estimate from them with the neighbourhood algorithm the 3 d wave speed variations and their uncertainty the crust structure parametrized in three layers can be well resolved with a horizontal resolution about of 100 km or less because of the possible effect of mechanically weak layers on regional deformation of particular interest is the existence and geometry of low shear velocity layers lvls in some regions prominent lvls occur in the middle crust in others they may appear in the lower crust in some cases the lateral transition of shear wave speed coincides with major fault zones the spatial variation in strength and depth of crustal lvls suggests that the 3 d geometry of weak layers is complex and that unhindered crustal flow over large regions may not occur consideration of such complexity may be the key to a better understanding of relative block motion and patterns of seismicity

the effectiveness of hillshade maps and expert knowledge in mapping old deep seated landslides large deep seated landslides with a shear surface deeper than 3 m and a mean affected area of 4 2 ha are common features in the flemish ardennes none of these deep seated landslides are dated but they are assumed to be rather old 100 years because most of these landslides are located under forest aerial photo interpretation commonly used for the creation of landslide inventories is not a suitable tool to map the landslides in the flemish ardennes therefore an intensive 100 day field survey was carried out by two geomorphologists in a 430 km 2 study area this resulted in a landslide inventory map indicating the location of 135 large deep seated landslides but field surveys are time consuming and thus very expensive therefore a cheaper and faster mapping technique was tested a hillshade map was constructed for the study area in a gis idris132 from a 5 m resolution digital elevation model dem seven experts were given 1 h to indicate all the hillslope sections which they suspected to be possible landslides on a copy of the aforementioned map scale 1 100 000 in total this exercise took only 1 day i e 7 person hours large differences in the number of presumed landslides and the extent of the hillslopes thought to be affected by landslides were reported among the seven experts the polygon and pixel efficiency were introduced to estimate the quality of the landslide maps based on hillshade maps and expert knowledge compared to the field survey based landslide inventory the quality of the landslide inventories based on the hillshade maps and expert knowledge was relatively low experts familiar with the study area obtained somewhat better results than experts who visited the study area only once a combination of the seven expert maps did not result in a good inventory map because too many unaffected hillslopes were incorrectly indicated as affected by landslides the results obtained in this study are comparable to an investigation carried out by wills c j mccrink t p 2002 comparing landslide inventories the map depends on the method environmental and engineering geoscience 8 279 293 although the tested method can never replace a detailed field survey taking into account the proposed improvements it can be used for the creation of a regional inventory map of old landslides in a densely forested area where light detection and ranging lidar data are unavailable c 2004 elsevier b v all rights reserved

gravity and magnetic anomalies in the allochthonous ordenes complex variscan belt northwest spain assessing its internal structure and thickness 1 the ordenes complex is the largest variscan allochthonous structure of nw iberia and preserves the suture of a long standing paleozoic ocean probably the rheic gravity and magnetic data the latter specifically acquired on land for this study show that the complex occupies the core of an open synform with a maximum depth of 9 10 km which contrasts with the flat geometry of the lower crust and moho discontinuity beneath the maximum depth reached by the ophiolitic rocks marking the suture is around 7 km the allochthonous units formed by basic and ultrabasic rocks are lens shaped in section and occur not only at the periphery of the complex but form wide ribbons trending ne sw to n s the bouguer anomaly related with the longest of them the fornas unit previously used to support an autochthonous interpretation of the complexes is modeled as a rootless massive amphibolite body with a maximum thickness of 6 km located at the downthrown block of a large normal fault cutting across previous thrust faults and extensional detachments the main magnetic anomalies are associated with ultrabasic rocks cropping out in the nw and se but a weak wide anomaly in the central part of the complex is related with one or more thin layers of amphibolite partly mineralized with massive sulphides the weakly arcuate geometry of this anomaly and of the bouguer anomaly caused by the fornas unit may reflect the ne flank of the central iberian arc an orocline whose core is occupied by the allochthonous complexes

landslides earthquakes and erosion this paper relates landslide inventories to erosion rates and provides quantitative estimates of the landslide hazard associated with earthquakes we do this by utilizing a three parameter inverse gamma distribution which fits the frequency area statistics of three substantially dcompletet landslide event inventories a consequence of this general distribution is that a landslide event magnitude ml lognlt can be introduced where nlt is the total number of landslides associated with the landslide event using this general distribution landslide event magnitudes ml can be obtained from incomplete landslide inventories and the total area and volume of associated landslides as well as the area and volume of the maximum landslides can be directly related to the landslide event magnitude using estimated recurrence intervals for three landslide events and the time span for two historical inventories we estimate regional erosion rates associated with landslides as typically 0 1 2 5 mm year 1 we next give an empirical correlation between the earthquake magnitude associated landslideevent magnitude and the total volume of associated landslides using these correlations we estimate that the minimum earthquake magnitudes that will generate landslides is m 4 3f0 4 finally using gutenberg richter frequency magnitude statistics for regional seismicity we relate the intensity of seismicity in an area and the magnitude of the largest regional earthquakes to erosion rates we find that typical seismically induced erosion rates in active subduction zones are 0 2 7 mm year 1 and adjacent to plate boundary strike slip fault zones are 0 01 0 7 mm year 1

magmatism on rift flanks insights from ambient noise phase velocity in afar region during the breakup of continents in magmatic settings the extension of the rift valley is commonly assumed to initially occur by border faulting and progressively migrate in space and time toward the spreading axis magmatic processes near the rift flanks are commonly ignored we present phase velocity maps of the crust and uppermost mantle of the conjugate margins of the southern red sea afar and yemen using ambient noise tomography to constrain crustal modification during breakup our images show that the low seismic velocities characterize not only the upper crust beneath the axial volcanic systems but also both upper and lower crust beneath the rift flanks where ongoing volcanism and hydrothermal activity occur at the surface magmatic modification of the crust beneath rift flanks likely occurs for a protracted period of time during the breakup process and may persist through to early seafloor spreading

slab break offs in the alpine subduction zone after the onset of plate collision in the alps at 32 34 ma the deep structure of the orogen is inferred to have changed dramatically european plate break offs in various places of the alpine arc as well as a possible reversal of subduction polarity in the eastern alps have been proposed we review different high resolution tomographic studies of the upper mantle and combine shear and body wave models to assess the most reliable geometries of the slabs several hypotheses for the tectonic evolution are presented and tested against the tomographic model interpretations and constraints from geologic and geodetic observations we favor the interpretation of a recent european slab break off under the western alps in the eastern alps we review three published scenarios for the subduction structure and propose a fourth one to reconcile the results from tomography and geology we suggest that the fast slab anomalies are mainly due to european subduction adriatic subduction plays no or only a minor role along the tauern window sections possibly increasing towards the dinarides the apparent northward dip of the slab under the eastern alps may be caused by imaging a combination of adriatic slab from the dinaric subduction system and a deeper lying european one as well as by an overturned retreating european slab

anelastic earth structure from the coherency of the ambient seismic field 1 cross correlation of the ambient seismic field is now routinely used to measure seismic wave travel times however relatively little attention has been paid to other information that could be extracted from these signals in this paper we demonstrate the relationship between the spatial coherency of the ambient field and the elastodynamic green s function in both time and frequency domains through measurement of the frequency domain coherency as a function of distance we sequentially recover phase velocities and attenuation coefficients from these measurements we generate 1 d shear wave velocity and attenuation models for southern california the ambient field measurements of attenuation and the exceptional path coverage that results from the many possible interstation measurements allow us to extend q estimates over a range of frequencies that has previously been difficult to analyze using earthquake data measurements from paths that cross major sedimentary basins show both lower wave speeds and lower quality factors than other paths as expected our results indicate that there is a wealth of information available in the spatial coherency of the ambient seismic field

shallow s wave velocity structure from ambient seismic noise at planchon peteroa volcanic complex argentina chileshallow s wave velocity structure from ambient seismic noise at planchon peteroa

one dimensional models of shear wave velocity for the eastern mediterranean obtained from the inversion of rayleigh wave phase velocities and tectonic implications summary on a sw ne profile from the libyan coast towards central turkey phase velocity curves of the fundamental rayleigh mode were measured using a two station method the inversion of phase velocity curves yields 1 d models of shear wave velocity down to approximately 200 km depths that may be interpreted as estimates of average models between neighbouring stations on the profile strong lateral variations in the shear wave velocity structure are imaged along the profile the subducted oceanic african mantle lithosphere is indicated in 1 d models for the region around crete by significantly enlarged shear wave velocities it is also imaged by an average model of the structure between stations on crete and santorini on a path crossing the libyan sea south of crete the resulting model is slower than a model expected for 110 myr old oceanic lithosphere the passive african margin is thus assumed to extend northwards beneath the libyan sea anomalous low shear wave velocities are found for the uppermost mantle beneath central turkey down to a depth of approximately 130 km using two stations on crete the average depth of the oceanic moho within the subducting slab is estimated to be at approximately 50 km beneath crete for this arc parallel path an enlarged standard deviation of the measured phase velocities of approximately 0 2 km s 1 between 10 and 30 mhz is observed that is probably caused by strong lateral heterogeneity related to the subducting slab in addition in this frequency range an anomalous propagation of the fundamental rayleigh mode is detected that is indicated by measured phase velocities that are approximately one standard deviation faster than phase velocities expected from a great circle approximation an average shear wave velocity of approximately 3 5 km s 1 is observed above the oceanic moho in order to explain the recent lithospheric structure of the hellenic subduction zone a tectonic model is assumed for the ne sw striking profile considered it is based on the calculated 1 d models tectonic reconstructions and on a model derived from the metamorphic history of rocks exposed on crete the suggested model summarizes the tectonic development at a lithospheric scale starting in the late cretaceous accretion of crustal material of two microcontinents to eurasia is assumed while continuous subduction of the oceanic lithosphere of different ocean basins and possibly of the mantle lithosphere of the microcontinents resulted in a single slab the length of the oceanic lithosphere that was subducted south of crete is estimated to be not greater than approximately 550 km

layered azimuthal anisotropy of rayleigh wave phase velocities in the european alpine lithosphere inferred from ambient noise abstract passive seismic imaging of the earth is a rapidly developing field of study recent advances in noise cross correlation techniques allow imaging of isotropic surface wave and shear wave velocities in areas where earthquake numbers and distributions are insufficient to implement traditional earthquake based tomography furthermore advances in the theory underpinning surface wave inversion have led to depth dependent mapping of seismic anisotropy in the lithosphere and upper asthenosphere we show that by merging these two rapidly advancing fields we can invert noise based phase velocity measurements for azimuthally anisotropic phase speed thereby providing a highly resolved image of layered azimuthal anisotropy in continental crust we apply this new algorithm in the western alps an area of complex lithospheric structure alpine crustal thickening results from continental collision indentation of the ivrea mantle into the middle crust of the european plate rollback of the european lithospheric mantle and crustal slicing we find that anisotropy beneath the central alps is stratified in two layers one with an orogen parallel fast direction above 30 km depth and another with a strong orogen perpendicular fast direction at greater depth although our resolution is reduced outside the central alps we map orogen parallel anisotropy in the crust of the northern alpine foreland we interpret the results in the central alps as first order evidence for a model of azimuthal anisotropy in which 1 near vertical emplacement of crustal slices following detachment of the lithospheric mantle from the crust gives rise to orogen parallel fast directions of wave propagation in the crust and 2 dominantly horizontal tectonics in the thickened crustal root and uppermost mantle yield orogen perpendicular fast directions at greater depth

tibetan and indian lithospheres in the upper mantle beneath tibet evidence from broadband surface wave dispersion broadband seismic experiments over the last two decades have produced dense data coverage across tibet yet the mechanism of the india asia lithospheric convergence beneath it remains a puzzle with even its basic features debated and with very different end member models advocated today we measured highly accurate rayleigh and love wave phase velocity curves in broad period ranges up to 5 200 s for a few tens of pairs and groups of stations across tibet combining in each case hundreds to thousands of interstation measurements made with cross correlation and waveform inversion methods robust shear velocity profiles were then determined by extensive series of nonlinear inversions of the data designed to constrain the depth dependent ranges of isotropic average shear speeds and radial anisotropy temperature anomalies in the upper mantle were estimated from shear velocities using accurate petrophysical relationships our results reveal strong heterogeneity in the upper mantle beneath tibet very large high velocity anomalies in the upper mantle are consistent with the presence of underthrust beneath southwestern tibet and subducted beneath central and eastern tibet indian lithosphere the corresponding thermal anomalies match those estimated for subducted indian lithosphere in contrast to the indian lithosphere tibetan lithosphere and asthenosphere display low to normal shear speeds tibetan lithosphere is thus warm and thin radial anisotropy in the upper mantle is weak in central and strong in northeastern tibet possibly reflecting asthenospheric flow above the subducting indian lithospheric slab

complex layered deformation within the aegean crust and mantle revealed by seismic anisotropy continental lithosphere can undergo pervasive internal deformation often distributed over broad zones near plate boundaries however because of the paucity of observational constraints on three dimensional movement at depth patterns of flow within the lithosphere remain uncertain endmember models for lithospheric flow invoke deformation localized on faults or deep shear zones or alternatively diffuse viscous fluid like flow here we determine seismic rayleigh wave anisotropy in the crust and mantle of the aegean region an archetypal example of continental deformation our data reveal a complex depth dependent flow pattern within the extending lithosphere beneath the northern aegean sea fast shear wave propagation is in a north south direction within the mantle lithosphere parallel to the extensional component of the current strain rate field in the south central aegean where deformation is weak at present anisotropic fabric in the lower crust runs parallel to the direction of palaeo extension in the miocene the close match of orientations of regional scale anisotropic fabric and the directions of extension during the last significant episodes of deformation implies that at least a large part of the extension in the aegean has been taken up by distributed viscous flow in the lower crust and lithospheric mantle

love and rayleigh phase velocity maps 5 40 s of the western and central usa from usarray data abstract continuous data recorded on more than 1600 usarray seismic stations operating in the western and central us between 2006 and 2012 are used to map phase velocities of love and rayleigh waves at short periods 5 40 s using a noise correlation technique vertical and transverse records for all station pairs separated by less than 600 km are cross correlated in 4 h long segments and the resulting spectra are stacked for the time period of station operation dispersion curves are determined from the locations of zeros in the real component of the correlation spectra using a method based on that of aki 1957 phase velocity maps expanded on a 0 25 by 0 25 pixel grid are estimated by inversion of the phase velocity measurements comparison with predicted phase velocity maps based on the crustal model crust2 0 combined with the mantle model nd08 shows good agreement at the longer periods strong slow anomalies 25 in the short period maps are geographically correlated with basins and regions of thick sedimentary cover the strength of these anomalies is not well predicted by existing crustal velocity models

use of lidar derived images for mapping old landslides under forest large deep seated landslides are common features in the flemish ardennes belgium as most of these old 100 years landslides are located under forest in this hilly region aerial photograph interpretation is not an appropriate landslide mapping method this study tested the potential of lidar light detection and ranging images for mapping old landslides under forest landslide inventory maps were created for a 125 km2 area by applying the expert knowledge of seven geomorphologists to lidar derived hillshade slope and contour line maps in a gis environment each of the seven lidar based landslide inventories was compared i with the other six ii with a detailed field survey based inventory and iii with a comparable study in which topographic data were extracted from a topographical map the combination of the percentage of field landslides indicated by an expert and the percentage of positional discrepancies expressed in terms of positional mismatch were used to evaluate the quality of the lidar based inventory maps high quality lidar derived landslide inventory maps contain more than 70 per cent of the landslides mapped during the field survey and have positional discrepancies smaller than 70 per cent when compared with the field survey based inventory map four experts and the combination map of all experts satisfied these criteria together the seven experts indicated all landslides mapped in the field importantly lidar enabled the experts to find ten new landslides and to correct the boundaries of eleven of the 77 landslides mapped during the field survey hence this study showed that large scale lidar derived maps analysed by experienced geomorphologists can significantly improve field survey based inventories of landslides with a subdued morphology in hilly regions copyright 2006 john wiley sons ltd

phase velocities of rayleigh and love waves in central and northern europe from automated broad band interstation measurements the increasingly dense coverage of europe with broad band seismic stations makes it possible to image its lithospheric structure in great detail provided that structural information can be extracted effectively from the very large volumes of data we develop an automated technique for the measurement of interstation phase velocities of earthquake excited fundamental mode surface waves in very broad period ranges we then apply the technique to all available broad band data from permanent and temporary networks across europe in a new implementation of the classical two station method rayleigh and love dispersion curves are determined by cross correlation of seismograms from a pair of stations an elaborate filtering and windowing scheme is employed to enhance the target signal and makes possible a significantly broader frequency band of the measurements compared to previous implementations of the method the selection of acceptable phase velocity measurements for each event is performed in the frequency domain based on a number of fine tuned quality criteria including a smoothness requirement between 5 and 3000 single event dispersion measurements are averaged per interstation path in order to obtain robust broad band dispersion curves with error estimates in total around 63 000 rayleigh and 27 500 love wave dispersion curves between 10 and 350 s have been determined with standard deviations lower than 2 per cent and standard errors lower than 0 5 per cent comparisons of phase velocity measurements using events at opposite backazimuths and the examination of the variance of the phase velocity curves are parts of the quality control with the automated procedure large data sets can be consistently and repeatedly measured using varying selection parameters comparison of average interstation dispersion curves obtained with different degrees of smoothness shows that rough perturbations do not systematically bias the average dispersion measurement they can therefore be treated as random but they do need to be removed in order to reduce random errors of the measurements using our large new data set we construct phase velocity maps for central and northern europe according to checkerboard tests the lateral resolution in central europe is 150 km comparison of regional surface wave tomography with independent data on sediment thickness in north german basin and polish trough confirms the high resolution potential of our phase velocity measurements at longer periods the structure of the lithosphere and asthenosphere around the trans european suture zone tesz is seen clearly the region of the tornquist teisseyre zone in the southeast is associated with a stronger lateral contrast in lithospheric thickness across the tesz compared to the region across the sorgenfrei tornquist zone in the northwest

the structure of the crust and uppermost mantle beneath south china from ambient noise and earthquake tomography summary two years of continuous recordings of ambient seismic noise observed at 354 stations in south china from 2009 to 2010 are used to estimate rayleigh wave group and phase velocity maps from 6 to 40 s period these results are merged with rayleigh wave phase velocity maps from 25 to 70 s period derived from earthquakes in the same time frame eikonal tomography generates the dispersion maps which by monte carlo inversion are used to estimate a 3 d vsv model of the crust and upper mantle down to a depth of 150 km across all of south china with attendant uncertainties a clear image emerges of the west yangtze block a region of the western yangtze craton characterized by relatively thick crust 40 km overlying a seismic mantle lithosphere that extends to at least 150 km that may have been the nucleus for the formation of the yangtze craton in the archean and may present a present day obstacle to the eastward expansion of tibet the west yangtze block contrasts with the thinner crust 30 km and mantle lithosphere 70 80 km beneath the eastern yangtze craton and south china foldbelt these observed differences are consistent with processes associated with flat slab subduction in the mesozoic that may have eroded the lithosphere of the eastern yangtze craton and the south china foldbelt

the influence of nonuniform ambient noise on crustal tomography in europe 1 ambient noise seismology is of great relevance to high resolution crustal imaging thanks to the unprecedented dense data coverage it affords in regions of little seismicity under the assumption of uniformly distributed noise sources it has been used to extract the green s function between two receivers we determine the imprint of this assumption by means of wave propagation and adjoint methods in realistic 3 d earth models in this context we quantify the sensitivity of ambient noise cross correlations from central europe with respect to noise source locations and shear wave speed structure we use ambient noise recorded over 1 year at 196 stations resulting in a database of 864 cross correlations our mesh is built upon a combined crustal and 3 d tomographic model we simulate synthetic ambient noise cross correlations in different frequency bands using a 3 d spectral element method traveltime cross correlation measurements in these different frequency bands define the misfit between synthetics and observations as a basis to compute sensitivity kernels using the adjoint method we perform a comprehensive analysis varying geographic station and noise source distributions around the european seas the deterministic sensitivity analysis allows for estimating where the starting crustal model shows better accordance with our data set and gain insight into the distribution of noise sources in the european region this highlights the potential importance of considering localized noise distributions for tomographic imaging and forms the basis of a tomographic inversion in which the distribution of noise sources may be treated as a free parameter similar to earthquake tomography

three dimensional crustal s wave velocity structure in japan using microseismic data recorded by hi net tiltmeters 1 we developed a three step method for three dimensional 3 d s wave velocity tomography by fitting synthetic cross spectra to the observed ones of ambient seismic noise we applied this method to the recording of hi net tiltmeters in japan at 679 stations from june 2004 to december 2004 first we calculated normalized cross spectra between radial components and those between transverse components for every pair of stations the first step is local 1 d s wave velocity inversion for each station assuming small lateral heterogeneity under a 100 km circle of a station we measured the dispersion curves of fundamental rayleigh waves fundamental love waves and first overtone of love waves by fitting the synthetic cross spectra to the observed ones between pairs of stations within the circle we inverted the measured dispersion curves for obtaining a 1 d s wave velocity model the second step is the inversion of the observed cross spectra for obtaining path averaged 1 d s wave velocity structure the third step is the inversion of the resultant path averaged structures for obtaining 3 d s wave velocity structure 0 1 0 1 1 km grid from the surface to a depth of 50 km using ray approximation the resultant s wave velocity structures show clear low velocity anomalies along tectonic lines from the surface to a depth of 20 km in particular along the hidaka mountain range we observed s wave perturbation more extreme than 20 they also show low velocity anomalies under volcanoes in kyusyu and tohoku in the southwestern part of shikoku our results show a clear low velocity anomaly corresponding to an accretional belt shimanto belt below 20 km we observe a low velocity anomaly in the center of japan which suggests a thick crust citation nishida k h kawakatsu and k obara 2008 three dimensional crustal s wave velocity structure in japan using microseismic data recorded by hi net tiltmeters j geophys res 113 b10302 doi 10 1029 2007jb005395

velocity measurement bias of the ambient noise method due to source directivity a case study for the swedish national seismic network the bias of velocity measurements from ambient noise covariograms due to an anisotropic distribution of noise sources is studied assuming that the noise field consists of planar surface waves from

wavelet analyses of mars polar topography we have analyzed topography tracks over the mars northern polar cap composed of h2o ice co2 ice and sediments and the antarctic ice sheet on earth using a mexican hat wavelet transform the great utility of the wavelet transform is that it gives both spatial and spectral resolution we have used the variance of the wavelet output in order to quantify the spectral content of the topography tracks at short wavelengths for both the mars northern polar cap and the antarctic ice sheet we find a power law dependence of the wavelet transform variance on wavelength with a power law exponent of 3 5 3 7 this compares with a power law exponent of 2 0 brownian motion typical of topography on both mars and earth there is a power law smoothing of the ice topography at short wavelengths on both planetary bodies at long wavelengths we infer a similar power law dependence with 1 5 2 0 typical of planetary topography a transition is observed between the smooth short wavelength behavior high to rougher long wavelength behavior low this fairly sharp transition occurs at a wavelength of 24 km for mars and 11 km for antarctica the transitions appear to scale with ice thicknesses and suggest a relaxation of short wavelength topography by ice flows or surface processes

tomography of the alpine region from observations of seismic ambient noise we use correlations of the ambient seismic noise to study the crust in western europe cross correlation of 1 year of noise recorded at 150 three components broadband stations yields more than 3 000 rayleigh wave group velocity measurements these measurements are used to construct rayleigh group velocity maps of the alpine region and surrounding area in the 5 80 s period band in the 5 10 s period band the seismic noise recorded in europe is dominated by surface waves originating from the northern atlantic ocean this anisotropy of the noise and the uneven station distribution affect the azimuthal distribution of the paths where we obtain reliable group velocity measurements as a consequence our group velocity models have better resolution in the northeast direction than in the southwest direction finally we invert the resulting rayleigh wave group velocity maps to determine the moho depth our results are in good agreement with the result of the numerous active experiments in the alps and provide a continuous image of the alpine structure