interferometric seismic imaging around the active lalor mine in the flin flon greenstone belt canada abstract seismic interferometry which recovers the impulse response of the earth by cross correlation of ambient noise recorded at sets of two receivers has found several applications including the generation of virtual shot gathers for use in seismic reflection processing to evaluate the effectiveness of this passive recording technique in mineral exploration in a hard rock environment 336 receivers recorded 300 h of ambient noise over the volcanogenic massive sulphide deposit of the recently discovered lalor mine in the canadian flin flon greenstone belt a novel time domain beamforming algorithm was developed to search for individual source locations demonstrating that the vast majority of noise originated from the mine and ventilation shafts of the lalor mine the results of the beamforming were utilized in conjunction with frequency wavenumber filtering to remove undesirable mostly monochromatic surface wave noise originating from nearby sources virtual shot gathers were generated along three receiver lines each of which was processed as a separate 2 d reflection line two of the resulting unmigrated reflection profiles are compared against coincident dipmoveout stacked data from a larger coincident 3 d dynamite seismic survey that was also acquired over the lalor mine in 2013 using knowledge of the local geology derived from numerous boreholes coherent events recovered in the passive reflection profiles are inferred to be either spurious arrivals or real reflections some of which can be interpreted in terms of geological contacts indicating the future potential of passive recording surveys in hard rock settings

imaging and interpreting the shallow crystalline crust abstract in the past many tests of high resolution seismic imaging methods utilizing off the shelf technology from hydrocarbon exploration have had only limited success some problems associated with the application of seismic profiling in the shallow crystalline crust differ from those encountered in sedimentary basins perhaps the most fundamental distinction stems from differences in statistical properties of the reflection coefficient time series analysis of power spectra derived from borehole data indicates that the reflection coefficients in the crystalline crust are depleted in the seismic bandwidth relative to sedimentary basins this fundamental difference must be considered in the design of shallow crustal seismic surveys in order to achieve success to a first approximation acoustic impedance variations in sedimentary basins are controlled by velocity changes whereas velocity and density can vary independently in the crystalline crust and changes in density may be relatively more important in controlling reflectivity in certain instances density fluctuations outweigh velocity fluctuations for example physical rock property data from mining districts in the canadian shield suggest that massive fe oxide or sulphide bodies will generate strong seismic reflections

elastic finite difference modeling of volcanic hosted massive sulfide deposits a case study from half mile lake new brunswick canada abstractwe present elastic finite difference modeling results over a geologically realistic 2d representation of the half mile lake volcanic hosted massive sulfide deposit new brunswick canada the model is constrained by geologic information from surface mapping and boreholes whereas petrophysical properties are provided by wireline logging data acquired in two boreholes intersecting different parts of the deposit we analyzed the p p p s s p and s s responses of the lower and deep mineralized zones and assessed some compositional effects by substituting massive sulfides with gabbro properties in the model finite difference modeling results predict complex scattering signature associated with the lower and deep sulfide zones both zones scattered back p p p s s p and s s waves generally having strongest amplitudes in the stratigraphy down dip direction the p s s p and s s scattered waves if properly recorded on multicomponent data represent useful signal that could help the targeting of de

tutorial on seismic interferometry part 1 basic principles and applications seismic interferometry involves the crosscorrelation of responses at different receivers to obtain the green s function between these receivers for the simple situation of an impulsive plane wave propagating along the x axis the crosscorrelation of the responses at two receivers along the x axis gives the green s function of the direct wave between these receivers when the source function of the plane wave is a transientas in exploration seismology or a noise signalas in passive seismology then the crosscorrelation gives the green s function convolved with the autocorrelation of the source function direct wave interferometry also holds for 2d and 3d situations assuming the receivers are surrounded by a uniform distribution of sources in this case the main contributions to the retrieved direct wave between the receivers come from sources in fresnel zones around stationary points the main application of direct wave interferometry is the retrieval of seismic surface wave responses from ambient noise and the subsequent tomographic determination of the surfacewave velocity distribution of the subsurface seismic interferometry is not restricted to retrieving direct waves between receivers in a classic paper claerbout shows that the autocorrelation of the transmission response of a layered medium gives the plane wave reflection response of that medium this is essentially 1d reflected wave interferometry similarly the crosscorrelation of the transmission responses observed at two receivers of an arbitrary inhomogeneous medium gives the 3d reflection response of that medium one of the main applications of reflected wave interferometry is retrieving the seismic reflection response from ambient noise and imaging of the reflectors in the subsurface a common aspect of direct and reflected wave interferometry is that virtual sources are created at positions where there are only receivers without requiring knowledge of the subsurface medium parameters or of the positions of the actual sources

the effects of double fault bends on rupture propagation a geometrical parameter study we use the 2d finite element method to determine how geometrical parameters determine whether rupture will propagate across a linked stepover in a strike slip fault the end segments of the fault system are aligned in the direction of maximum shear and the length and angle of the linking segment are allowed to vary we observe that ruptures propagate through extensional stepovers with steeper angles and longer linking segments than otherwise equivalent compressional step overs these different rupture behaviors form distinct regions in angle stepover length parameter space the boundary between these regions takes the shape of an asymptotic curve in both the extensional and compressional cases models in which the size of the entire fault system was made larger or smaller revealed that the location of the bound aries between regions of different rupture behavior do not scale linearly with the system size it was easier to rupture steeper and relatively longer stepovers in fault systems that were larger overall a separate set of models in which the stress field is rotated so that the parallel end segments were optimally aligned for rupture significantly altered the rupture behavior curves in this stress field it was easier to rupture compressional stepovers with steeper angles and longer linking segments than it was to rupture equivalent extensional stepovers in both the case in which the end segments are aligned with the direction of maximum shear and the case in which the end segments are optimally oriented for rupture the angles at which rupture could no longer propagate through the entire fault corresponded with peaks in the fault s s value

permian continental basins in the southern alps italy and peri mediterranean correlations the late carboniferous to permian continental successions of the southern alps can be subdivided into two main tectono sedimentary cycles separated by a marked unconformity sealing a middle permian time gap generally estimated at over 10 ma the lower cycle 1 between the variscan crystalline basement and the early permian is mainly characterised by fluvio lacustrine and volcanic deposits of calc alkaline acidic to intermediate composition which range up to a maximum thickness of more than 2 000 m the upper cycle 2 which is devoid of volcanics is mostly dominated through the mid late permian by alluvial sedimentation which covered the previous basins and the surrounding highs giving rise to the subaerial verrucano lombardo val gardena groden red beds up to about 800 m thick the palaeontological record from the terrigenous deposits of both the above cycles consists mainly of macro and microfloras and tetrapod footprints the age of the continental deposits is widely discussed because of the poor chronological significance of a large number of fossils which do not allow reliable datings however some sections are also controlled by radiometric calibrations the comparison with some selected continental successions in southern europe allows to determine their evolution and set up correlations a marked stratigraphic gap shows everywhere between the above mentioned cycles 1 and 2 as in the southern alps the gap reaches the greatest extent during the mid permian near the illawarra reversal geomagnetic event 265 ma in western europe however such as in provence and sardinia the discussed gap persists upwardly to late permian and early triassic or slightly younger times i e to the onset of the alpine sedimentary cycle even though in northeastern spain iberian ranges balearic islands this gap results clearly interrupted by late guadalupian lopingian deposits the above two major tectonosedimentary cycles reflect in our view two main geodynamic events that affected the southern europe after the variscan orogenesis the late carboniferous early permian transformation of the gondwana eurasia collisional margin into a diffuse dextral transform margin and the middle late permian opening of the neotethys ocean with the onset of a generalised extensional tectonic regime and the progressive westward marine ingression

shallow high resolution seismic imaging at the ansil mining camp in the abitibi greenstone belt volcanic rocks in and around the ansil mining camp host a large number of massive sulfide mineral deposits a high resolution seismic reflection profile was shot across the camp with the objective of mapping the contacts between the different volcanic units at which most of the ore bodies have been found numerous exploration boreholes define the geology to a depth of 1600 m and allow a precise comparison with the recorded reflections geophysical logs obtained in one deep borehole suggest that reflection coefficients between the andesite rhyolite units of the volcanic stratigraphy are around 0 05 but few corresponding reflections can be identified in the seismic data those reflections in the surface seismic profile that can be correlated with the subsurface geology originate from diorite sills at which reflection coefficients are between 0 05 and 0 11 we suggest that reflections are observed from the diorite sills because the sills were intruded as sheets some along fault planes resulting in inte

passive seismic interferometry by multidimensional deconvolution we introduce seismic interferometry of passive data by multidimensional deconvolution mdd as an alternative to the crosscorrelation method interferometry by mdd has the potential to correct for the effects of source irregularity assuming the first arrival can be separated from the full response mdd applications can range from reservoir imaging using microseismicity to crustal imaging with teleseismic data

seismic exploration scale velocities and structure from ambient seismic noise 1 hz the successful surface waves retrieval in solid earth seismology using long time correlations and subsequent tomographic images of the crust have sparked interest in extraction of subsurface information from noise in the exploration seismology subsurface information in exploration seismology is usually derived from body wave reflections 1 hz which is challenging for utilization of ambient noise we use 11 h of noise recorded in the sirte basin libya first we study the characteristics of the noise we show that the bulk of the noise is composed of surface waves at frequencies below 6 hz some noise panels contain nearly vertically traveling events we further characterize these events using a beamforming algorithm from the beamforming we conclude that these events represent body wave arrivals with a fairly rich azimuthal distribution having body wave arrivals in the noise is a prerequisite for body wave reflections retrieval we crosscorrelate and sum the recorded ambient noise panels to retrieve common source gathers following two approaches using all the noise and using only noise panels containing body wave arrivals likely to contribute to the reflections retrieval comparing the retrieved gathers with active seismic data we show that the two way traveltimes at short offsets of several retrieved events coincide with those of reflections in the active data and thus correspond to apexes of reflections we then compare retrieved stacked sections of the subsurface from both approaches with the active data stacked section and show that the reflectors are consistent along a line the results from the second approach exhibit the reflectors better

local site effects on weak and strong ground motion abstract this is a review of the current state of the art in characterizing effects of local geology on ground motion a new horizon is clear in this aspect of strong motion studies non linear amplification at sediment sites appears to be more pervasive than seismologists used to think several recent observations about the weak motion and the strong motion suggest that the non linear amplification at sediment sites may be very common first on average the amplification is always greater at the younger sediment sites for all frequencies up to 12 hz in the case of weak motion while the relation is reversed for frequencies higher than 5 hz in the case of strong motion secondly the application of the amplification factor determined from weak motion overestimates significantly the strong motion at sediment sites observed during the loma prieta earthquake within the epicentral distance of about 50 km thirdly the variance of peak ground acceleration around the mean curve decreases with the increasing earthquake magnitude finally the above non linear effects are expected from geotechnical studies both in the magnitude of departure from the linear prediction and in the threshold acceleration level beyond which the non linearity begins

heterogeneous fault stresses from previous earthquakes and the effect on dynamics of parallel strike slip faults 1 we combine a viscoelastic model for the interseismic process and an elastodynamic model for the coseismic process to explore the dynamics over multiple earthquake cycles of two parallel strike slip faults embedded in a two dimensional full space the step over fault geometry results in a buildup of heterogeneous fault stress near the step over this heterogeneous stress accumulates at the early stage of the evolution of the fault system and finally stabilizes after a number of earthquake cycles the heterogeneity in fault stress varies with the geometrical parameters e g width and along strike overlap gap of the step over as well as the rupture history of the fault system this heterogeneous fault stress from previous earthquakes has significant effects on earthquake rupture initiation propagation and termination the locations with a low normal stress level near a step over are favorable points for earthquake initiation rupture can jump a 4 km wide compressional step over and a 8 km or wider dilational step over if the fault system has historically experienced many earthquakes a young step over with less induced heterogeneity allows rupture to jump only smaller step over widths these results may have important implications for seismic hazard analysis in areas where segmented strikeslip faults predominate particularly for estimating maximum earthquake potential citation duan b and d d oglesby 2006 heterogeneous fault stresses from previous earthquakes and the effect on dynamics of parallel strike slip faults j geophys res 111 b05309 doi 10 1029 2005jb004138

construction of equivalent single planar fault model for strike slip stepovers abstract non planarity is a common and natural characteristic of seismic faults that strongly affects the rupture dynamics and the associated seismic waves geometrically uniform planar fault model is widely used in studies of kinematic source inversion seismic hazard estimation and rupture dynamic simulation because of the simplicity and computational efficiency of this method the influence of the geometric heterogeneity of faults on rupture dynamics and associated seismic waves may under some circumstances be reasonably approximated by an appropriate heterogeneous distribution of shear strength of planar faults particularly for the case with uniform initial stress distribution an outstanding issue is how to approximate the dynamic behavior of a non planar fault by means of heterogeneous properties on a planar fault thus we propose the construction of an equivalent planar fault model for a given stepover fault through the introduction of a heterogeneous distribution of static friction coefficient our study shows that the distribution of static friction coefficient on the equivalent planar fault model is mainly controlled by the geometric irregularities of the stepovers regardless of the initial shear stress thereby providing a way to quantify the effect of fault geometry particularly the step width effect in seismic hazard estimation moreover our results indicate that the influence of geometric discontinuity of stepovers on rupture dynamics is equivalent to a barrier of the planar fault model

shear wave imaging from traffic noise using seismic interferometry by cross coherence we apply the cross coherence method to the seismic interferometry of traffic noise which originates from roads and railways to retrieve both body waves and surface waves our preferred algorithm in the presence of highly variable and strong additive random noise uses cross coherence which uses normalization by the spectral amplitude of each of the traces rather than crosscorrelation or deconvolution this normalization suppresses the influence ofadditive noise and overcomes problems resulting from amplitudevariations among input traces by using only the phase information and ignoring amplitude information the method effectively removes the source signature from the extracted response and yields a stable structural reconstruction even in the presence of strong noise this algorithm is particularly effective where the relative amplitude among the original traces is highly variable from trace to trace we use the extracted reflected shear waves from the traffic noise data to construct a stackedandmigratedimage andweusetheextractedsurfacewaves love waves to estimate the shear velocity as a function of depth this profile agrees well with the interval velocity obtained from the normal moveout of the reflected shear waves constructed by seismic interferometry these results are useful in a wide range of situations applicable to both geophysics and civil engineering

rupture termination and jump on parallel offset faults proper evaluation of seismic hazard depends on accurate estimates of potential earthquake size in areas with complex multisegment fault systems such an estimate in turn depends on an ability to predict the circumstances under which rupture may jump between fault segments many observational and numerical studies have analyzed the phenomenon of jumping rupture but none has focused on how the process of rupture termination on the primary nucleating fault segment affects the ability of rupture to jump to a secondary fault segment in the current study i model the dynamics of a simple 2d strike slip fault system with two parallel segments arranged with either a compressional or extensional stepover i vary the suddenness with which the initial shear stress tapers to zero on the primary section if the initial shear stress goes to zero over a very small 100 m distance rupture readily jumps both compressional and extensional stepovers of 1 km if the initial shear stress tapers to zero over 1 km rupture can jump the compressional stepover but not the extensional stepover if the initial shear stress tapers to zero over 2 5 km rupture cannot jump either the compressional or the extensional stepover the results illustrate the importance of the slip gradient and the resultant static stress field and the acceleration of the rupture front and the resultant generation of stopping phases in determining the probability of jumping rupture

seismic methods for deep mineral exploration mature technologies adapted to new targets nonseismic methods such as electromagnetic induced polarization and potential field surveying techniques have been the geophysical backbone of mineral exploration for decades these methods exploit anomalous physical properties of ore deposits e g enhanced conductivity chargeability or magnetization to locate potential targets for drilling although well suited to many shallow 500 m exploration problems the underlying physical principles of these methods impose inescapable limitations on their sensitivity and resolving power at depth recent declines in base metal reserves caused by the depletion of known shallow deposits and declining rates of discovery for new deposits underscore the need for geophysical exploration methods that can locate economically viable deposits at depths of up to several km seismic methods offer one possible solution the need to develop efficient and robust seismic imaging techniques for mineral exploration has long been recognized in the 1980s two key case histories established the potential of seismics as a mapping tool in the hardrock environment green and mair 1983 presented seismic images of complex fracture systems at a radioactive waste disposal site in the canadian shield subsequently pretorius et al 1989 demonstrated the usefulness of an integrated seismic and petrophysical approach to image key geologic structures for mineral exploration in witwatersrand basin south africa these initial studies served as catalysts for a number of largely independent research efforts over the following decade in north america southern africa scandinavia and australia aimed at developing useful and cost effective seismic technology for deep mineral exploration and mine planning a number of fundamental aspects of seismic exploration for minerals including the acoustic properties of ores and the scattering characteristics of orebodies were poorly known until recently moreover significant advances have been made in seismic imaging technology for mineral exploration from downhole seismic techniques to large scale 3d surveys over known deposits this article reviews some advances in applying seismic

rupture propagation beyond fault discontinuities significance of fault strike and location summary earthquake rupture sometimes occurs on several faults and often decelerates or terminates at fault stepovers factors that control the rupture processes across stepovers are important for an understanding of earthquake growth and termination in this study we investigate such factors by calculating the spontaneous rupture processes of two non coplanar faults in a 3 d model dealing with two extreme models in which two strike slip faults are either parallel or perpendicular we show that the rupture processes beyond fault discontinuities are drastically different for the two models we find three factors influencing rupture processes beyond fault discontinuities depth of the upper edge of the two faults location of the edge of the first fault and geometry of the two faults these factors determine the time and location of rupture jumps to the second fault for rupture propagation to the second fault it is essential for rupture on the first fault to arrive at the edge of the fault in particular whether rupture on the first fault reaches the earth s surface or not controls the difficulty of rupture jumps and the locations where the rupture is triggered which is also related to the step direction of the two faults this is because the stress perturbation at the fault edge is affected by the earth s free surface

interferometric ground roll removal attenuation of scattered surface waves in single sensor data land seismic data are contaminated by surface waves or ground roll these surface waves are a form of source generated noise and can be strongly scattered by near surface heterogeneities the resulting scattered ground roll can be particularly difficult to separate from the desired reflection data especially when this scattered ground roll propagates in the crossline direction we have used seismic interferometry to estimate scattered surface waves recorded during an exploration seismic survey between pairs of receiver locations where sources and receivers coincide these interreceiver surface wave estimates were adaptively subtracted from the data this predictive subtraction process can successfully attenuate scattered surface waves while preserving the valuable reflected arrivals forming a new method of scattered ground roll attenuation we refer to this as interferometric ground roll removal

using supervirtual first arrivals in controlled source hardrock seismic imaging well worth the effort varied applications of seismic interferometry have arisen in the last decade however the potential of the method to improve reflection seismic processing in hardrock environments has not explicitly been regarded therefore in this paper we investigate the potential of retrieving the first arrivals originally hindered by high noise level in the exploitation of controlled source data acquired over the iron oxide apatite rich deposit at grangesberg sweden and its mining induced structures the supervirtual first arrivals retrieved using interferometry methodologies allowed first breaks to be picked more extensively than in the original data revised static corrections significantly improved the linearity of the first arrivals and continuity of reflections in the source gathers especially reflections considerably enhanced in the source gathers stacked constructively in the final section comparison with geological data supported by traveltime forward modelling indicates that these reflections represent the unmined part of the deposit other reflections at shallower depth are interpreted as anthropogenic faults possibly located at lithological contacts tomographic inversion was also run using the augmented traveltime data the greater resolution and penetration of this new tomographic image allowed better bridging with the results of the reflection seismic section velocity anomalies depict the presence of mining induced structures and a potential brewery fault which is believed to put at risks an urban area even though the potential of first arrival retrieval seems to be case dependent this study illustrates that interferometry may substantially improve the accuracy of static corrections and subsequent stack for hardrock imaging as well as in the penetration and resolution of traveltime tomograms

dynamic 3d simulations of earthquakes on en echelon faults one of the mysteries of earthquake mechanics is why earthquakes stop this process determines the difference between small and devastating ruptures one possibility is that fault geometry controls earthquake size we test this hypothesis using a numerical algorithm that simulates spontaneous rupture propagation in a three dimensional medium and apply our knowledge to two california fault zones we find that the size difference between the 1934 and 1966 parkfield california earthquakes may be the product of a stepover at the southern end of the 1934 earthquake and show how the 1992 landers california earthquake followed physically reasonable expectations when it jumped across en echelon faults to become a large event if there are no linking structures such as transfer faults then strike slip earthquakes are unlikely to propagate through stepover s 5 km wide

fault geometry rupture dynamics and ground motion from potential earthquakes on the north anatolian fault under the sea of marmara summary using the 3 d finite element method we develop dynamic spontaneous rupture models of earthquakes on the north anatolian fault system in the sea of marmara turkey considering the geometrical complexity of the fault system in this region we find that the earthquake size rupture propagation pattern and ground motion all strongly depend on the interplay between the initial static regional pre stress field and the dynamic stress field radiated by the propagating rupture by testing several nucleation locations we observe that those far from an oblique normal fault stepover segment near istanbul lead to large through going rupture on the entire fault system whereas nucleation locations closer to the stepover segment tend to produce ruptures that die out in the stepover however this pattern can change drastically with only a 10 rotation of the regional stress field our simulations also reveal that while dynamic unclamping near fault bends can produce a new mode of supershear rupture propagation this unclamping has a much smaller effect on the speed of the peak in slip velocity along the fault finally we find that the complex fault geometry leads to a very complex and asymmetric pattern of near fault ground motion including greatly amplified ground motion on the insides of fault bends the ground motion pattern can change significantly with different hypocentres even beyond the typical effects of directivity the results of this study may have implications for seismic hazard in this region for the dynamics and ground motion of geometrically complex faults and for the interpretation of kinematic inverse rupture models

reconstruction of subsurface structure from ambient seismic noise an example from ketzin germany summary passive seismic interferometry is a new promising methodology for seismic exploration interferometry allows information about the subsurface structure to be extracted from ambient seismic noise in this study we apply the cross correlation technique to approximately 25 hr of recordings of ambient seismic noise at the ketzin experimental co2 storage site germany common source gathers were generated from the ambient noise for all available receivers along two seismic lines by cross correlation of noise records this methodology isolates the interstation green s functions that can be directly compared to active source gathers we show that the retrieved response includes surface waves refracted waves and reflected waves we use the dispersive behaviour of the retrieved surface waves to infer geological properties in the shallow subsurface and perform passive seismic imaging of the subsurface structure by processing the retrieved reflected waves

heterogeneity and seismic scattering in exploration environments abstract seismic scattering and the corresponding reduction in signal to noise ratio is a severe limitation to seismic exploration in crystalline environments in this paper we summarize recent elastic numerical modeling of scattering regimes and discuss the implications for seismic exploration in shallow hardrock environments the resulting synthetic seismograms range from relatively transparent to highly reflective depending on the ratio of seismic wavelength to heterogeneity scale length we note that the archean canadian shield is characterized by large scale lengths typical for crystalline environments which translates to moderately reflective seismic sections exhibiting scattering features that are coherent over large distances in contrast the highly fractured footwall of the sudbury impact structure in the canadian shield translates to a medium with small to moderate scale lengths resulting in seismic sections that can in places be highly reflective or relatively transparent from the perspective of mineral exploration in sudbury we find that the possible detection of massive sulfide targets is dependent not only on the shape and size of the deposit but on the scattering nature of the background as well with information about the petrophysical properties and the distribution of heterogeneity within an exploration area acquisition parameters such as source frequencies and minimum receiver spacing can be adjusted in order to survey within the scattering regime that will produce the least amount of noise

global phase seismic interferometry unveils p wave reflectivity below the himalayas and tibet a number of seismic methods exist to image the lithosphere below a collection of receivers using distant earthquakes in the current practice especially mode conversions in teleseismic phases are utilized we present a new method that takes advantage of the availability of global phases this method is called global phase seismic interferometry glopsi with glopsi zero offset reflections are extracted from reverberations near the array caused by global seismicity we exemplify glopsi with data from the hi climb experiment 2002 2005 and migrate the obtained reflection responses this results in a 800 km long reflectivity profile through the himalayas and a large part of the tibetan plateau

direct migration of ambient seismic data abstract utilising ambient seismic energy naturally propagating in the earth as an alternative approach to active body wave seismic investigations has been a topic of interest for a number of decades however because ambient surface wave arrivals typically are of much greater amplitude than ambient body wave energy significant data signal processing and long recording times are required to mitigate this and other coherent noise sources and to correlate sufficient reflected body wave energy to converge to a stable image even for these scenarios identifying and validating imaged body wave reflection events remain challenging in active source investigations extended imaging condition gathers are used to examine velocity in accuracy herein we develop an ambient direct migration approach that uses a novel ambient deconvolution extended imaging condition we simulate synthetic ambient wavefield seismic data for two different models and use a field data set from lalor lake in manitoba canada to conduct a series of numerical experiments to demonstrate the velocity sensitivity and long term stationarity of ambient wavefield seismic data in the migration image domain tests with varying global velocity perturbations show a characteristic reflector moveout in deconvolution extended imaging condition gathers that can serve as a diagnostic of reflected ambient body wave energy we illustrate that this imaging formalism under idealised circumstances gives comparable results to conventional seismic methods which extends the use of extended imaging condition gather based image validation to ambient wavefield seismic data scenarios we assert that this may be a valuable tool for the validation of ambient migration techniques that to date have yielded largely inconclusive results

3d seismic reflection imaging of volcanic hosted massive sulfide deposits insights from reprocessing halfmile lake data new brunswick canada three dimensional seismic reflection data from the halfmile lake area new brunswick canada was reprocessed over an 18 km2 grid to improve the seismic signatures of a 5 million ton volcanic hosted massive sulfide vhms deposit located at 1200 m depth known as the deep zone as well as key host rock structures we chose a prestack dip moveout dmo and poststack migration processing sequence to preserve the possible diffraction signature of the deep vhms zone despite the high level of source generated noise and large statics caused by near surface conditions our processing results revealed improved 3d seismic images for shallow and deep structures many of the imaged structures were easily correlated with known lithological con tacts constrained by boreholes and petrophysical measurements a short flat lying segment of high amplitude reflection at about 800 m depth in the unmigrated cube was interpreted to originate from a small portion of the lower vhms zone the dmo stack was characterized by a l

body wave reconstruction from ambient seismic noise correlations in an underground mine abstractthe reconstruction of seismic green s functions from correlations of ambient seismic noise has recently developed as a promising approach for exploring the earth s interiors without the requirement of costly active seismic sources this approach is widely used for imaging the crust at a kilometer scale however few studies report noise based green s function reconstruction at smaller scales in industrial environments we have investigated the possibility of constructing seismic green s functions between sensors in an active underground mine garpenberg sweden by crosscorrelating seismic noise generated by mining activities we have determined with realistic numerical simulations that the mining excavations in an underground mine lead to a regime of strong scattering which is favorable for constructing seismic green s functions by crosscorrelating seismic noise one month of continuous data was recorded by 18 seismic sensors located more than 1 km below surface a variety of broadband 10 3000

improved target illumination at ludvika mines of sweden through seismic interferometric surface wave suppression in mineral exploration new methods to improve the delineation of ore deposits at depth are in demand for this purpose increasing the signal to noise ratio through suitable data processing is an

physical properties and seismic imaging of massive sulfides laboratory studies show that the acoustic impedances of massive sulfides can be predicted from the physical properties vp density and modal abundances of common sulfide minerals using simple mixing relations most sulfides have significantly higher impedances than silicate rocks implying that seismic reflection techniques can be used directly for base metals exploration provided the deposits meet the geometric constraints required for detection to test this concept a series of 1 2 and 3 d seismic experiments were conducted to image known ore bodies in central and eastern canada in one recent test conducted at the halfmile lake copper nickel deposit in the bathurst camp laboratory measurements on representative samples of ore and country rock demonstrated that the ores should make strong reflectors at the site while velocity and density logging confirmed that these reflectors should persist at formation scales these predictions have been confirmed by the detection of strong reflections from

high resolution lithospheric imaging with seismic interferometry in recent years there has been an increase in the deployment of relatively dense arrays of seismic stations the availability of spatially densely sampled global and regional seismic data has stimulated the adoption of industry style imaging algorithms applied to converted and scattered wave energy from distant earthquakes leading to relatively high resolution images of the lower crust and upper mantle we use seismic interferometry to extract reflection responses from the coda of transmitted energy from distant earthquakes in theory higher resolution images can be obtained when migrating reflections obtained with seismic interferometry rather than with conversions traditionally used in lithospheric imaging methods moreover reflection data allow the straightforward application of algorithms previously developed in exploration seismology in particular the availability of reflection data allows us to extract from it a velocity model using standard multichannel data processing methods however the success of our approach relies mainly on a favourable distribution of earthquakes in this paper we investigate how the quality of the reflection response obtained with interferometry is influenced by the distribution of earthquakes and the complexity of the transmitted wavefields our analysis shows that a reasonable reflection response could be extracted if 1 the array is approximately aligned with an active zone of earthquakes 2 different phase responses are used to gather adequate angular illumination of the array and 3 the illumination directions are properly accounted for during processing we illustrate our analysis using a synthetic data set with similar illumination and source side reverberation characteristics as field data recorded during the 2000 2001 laramie broad band experiment finally we apply our method to the laramie data retrieving reflection data we extract a 2 d velocity model from the reflections and use this model to migrate the data on the final reflectivity image we observe a discontinuity in the reflections we interpret this discontinuity as the cheyenne belt a suture zone between archean and proterozoic terranes

fault steps and the dynamic rupture process 2 d numerical simulations of a spontaneously propagating shear fracture fault steps may have controlled the sizes of the 1966 parkfield 1968 borrego mountain 1979 imperial valley 1979 coyote lake and the 1987 superstition hills earthquakes this project investigates the effect of fault steps of various geometries on the dynamic rupture process we have used a finite difference code to simulate spontaneous rupture propagation in two dimensions we employ a slip weakening fracture criterion as the condition for rupture propagation and examine how rupture on one plane initiates rupture on parallel fault planes the geometry of the two parallel fault planes allows for stepover widths of 0 5 to 10 0 km and overlaps of 5 to 5 km our results demonstrate that the spontaneous rupture on the first fault segment continues to propagate onto the second fault segment for a range of geometries for both compressional and dilational fault steps a major difference between the compressional and dilational cases is that a dilational step requires a longer time delay between the rupture front reaching the end of the first fault segment and initiating rupture on the second segment therefore our dynamic study implies that a compressional step will be jumped quickly whereas a dilational step will cause a time delay leading to a lower apparent rupture velocity we also find that the rupture is capable of jumping a wider dilational step than compressional step

reflection images from ambient seismic noise one application of seismic interferometry is to retrieve the impulse response green s function from crosscorrelation of ambient seismic noise various researchers show results for retrieving the surface wave part of the green s function however reflection retrieval has proven more challenging we crosscorrelate ambient seismic noise recorded along eight parallel lines in the sirte basin east of ajdabeya libya to obtain shot gathers that contain reflections we take advantage of geophone groups to suppress part of the undesired surface wave noise and apply frequency wavenumber filtering before crosscorrelation to suppress surface waves further after comparing the retrieved results with data from an active seismic exploration survey along the same lines we use the retrieved reflection data to obtain a migrated reflection image of the subsurface

feasibility of virtual source reflection seismology using interferometry for mineral exploration a test study in the lalor lake volcanogenic massive sulphide mining area manitoba canada approximately 300 hours of ambient noise data were recorded on a grid of receivers covering an area of 4 km2 over the lalor mine canada to test the capability of seismic interferometry to image ore deposits in the crystalline rock environment underground mining activities create the main source of ambient noise in the area alongside the ambient noise survey a larger three dimensional active source seismic survey was also acquired and used to evaluate the interferometry results power spectral density calculations show random ambient noise with a frequency range of 2 hz 35 hz a beamforming analysis identified body waves arriving from the west northwest pointing towards the mine and surface waves propagating from the northeast the calculated virtual shot gathers retrieved by cross correlating ambient noise at all receivers were processed following both two dimensional and three dimensional approaches using a sequence similar to the one applied to the activesource three dimensional data the dip moveout stacked section reveals a number of events similar to those observed on the processed active seismic sections in particular the passive seismic interferometry method is capable to partly image shallowly dipping reflections but did not produce convincing images of steeply dipping reflections dip moveout stacked sections obtained with different cross correlation time windows indicate that the strength and number of reflections generally increase with longer noise records however a few reflections at depth show reduced coherency with longer noise time windows the passive seismic interferometry results over the lalor mining area are encouraging but image quality of the passive survey is lower than the acquired active three dimensional survey at the area future ambient noise surveys with longer offsets shorter receiver spacing and wider azimuth distribution are needed in crystalline rock environment to address the potential of the method for mineral exploration

seismic reflection imaging over a massive sulfide deposit at the matagami mining camp quebec a 2 d seismic reflection profile was shot across the southern flank of the matagami mining camp almost directly above the recently discovered bell allard massive sulfide deposit now estimated at more than 6 million metric tons all orebodies found in the southern part of the mining camp including bell allard are located at the contact between the primarily basaltic wabassee group and the underlying rhyolitic watson lake group seismic reflections were recorded from the basalt rhyolite contacts of the lower wabassee group as well as from gabbro sills that intrude much of the volcanic stratigraphy a strong reflection from the top of the bell allard orebody was also detected but the reflection does not extend over the full width of the deposit as defined by drilling appearing to correlate with the lower pyrite rich zone faulting which can be interpreted from discontinuities in the observed reflections probably controlled the formation of the bell allard deposit if the interpreted gabbro sills are accepted as isotime markers then faulting of the deeper sill complex defines a series of half grabens within the rhyolitic watson lake group the bell allard deposit is found at the intersection of one of these apparently low angle normal faults with the top of the watson lake group indicating that sulfide mineralization may have been associated with fluid flow along the fault which likely penetrates to the underlying mafic intrusion although the precise geometry of subsurface faulting cannot be estimated from a single 2 d seismic profile these results indicate that a full 3 d seismic survey should allow the mapping of many of the subsurface fault systems and the verification of hypotheses of fault controlled deposit formation

seismic imaging of massive sulfide deposits part ii reflection seismic profiling seismic reflection profiling the dominant geophysical method for hydrocarbon exploration has the potential to provide images of regional structure for mineral exploration in the crystalline crust and direct detection of large massive sulfide orebodies previous tests of traditional seismic methods in hard rock environments have had mixed success based on these earlier results we have tailored acquisition and processing strategies to conditions in the canadian shield we illustrate these methods using an example from the sudbury basin a rich mineral producing region because of structural complexity that complicates interpretation of the seismic images the seismic data are integrated with detailed three dimensional forward modeling based on physical properties studies mine geology and well logging through this integrated approach we show that massive sulfides can produce a characteristic seismic reflection response and that surface seismic reflection profiling may be used to detect and delineate deep large massive sulfide deposits accurately in a complex geologic setting characterized by moderate dips

3d s wave velocity imaging of a subsurface disturbed by mining using ambient seismic noise abstract seismic interferometry based on ambient seismic noise was used to image the 3d s wave velocity field of a subsurface disturbed by mining under the geological conditions at the kghm rudna copper mine in southwestern poland we recorded ambient seismic noise data for 3 months using 11 surface mounted broadband seismometers located across the mining area we used ambient noise cross correlation techniques to create a three dimensional s wave velocity model of the cenozoic and triassic formations up to a depth of 500 m cross correlation functions ccfs indicate the rayleigh and love waves however only the love waves in the 0 19 0 4 hz frequency range were reliable based on the symmetry of the ccfs in the positive and negative conditions imaging using the love waves indicated that the changes in the s wave velocity field in the model may be explained by the subsidence processes occurring above the mined area the s wave velocity decreased above the areas of the current mining operations however the s wave velocity increased above older mined areas probably due to suppression of the subsidence process and progressive consolidation of the geological medium over time we also observed low velocity anomalies in the intersection zones of the larger faults with high energy seismic events this could be caused by fault activation by current mining operations and a reduction in the stiffness of the layers in the fault intersection zone this study presents the possibility of imaging the subsurface layers in a mining area using ambient seismic noise it also has the potential to give a broader insight into how a geological medium responds to mining in terms of protecting the terrain surface and developing mining technologies

seismic methods in mineral exploration and mine planning a general overview of past and present case histories and a look into the future abstractdue to high metal prices and increased difficulties in finding shallower deposits the exploration for and exploitation of mineral resources is expected to move to greater depths consequently seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration these methods also can be used with varying degrees of success to directly target mineral deposits at depth we review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions australia europe canada and south africa a wide range of case studies are covered including some that are published in the special issue accompanying this article from surface to borehole seismic methods as well as petrophysical data and seismic modeling of mineral deposits at present high resolution 2d surveys mostly are performed in mining areas but there is a general increasing trend in the use of 3

wavelet power spectra of aeolian sand transport by boundary layer turbulence 1 this letter reports on wavelet spectral analysis of collocated time series of streamwise wind speed and aeolian sand transport collected at 0 04 m above the bed in a field experiment on top of a large sand mound in a desert environment results suggest three distinct spatio temporal scales of interaction between boundary layer turbulence and sediment transport a long term scale associated with the regional mixing layer an integral time scale associated with the internal boundary layer and a streamer scale associated with the inertial subrange eddy cascade and saltation inertia

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

introduction to special issue on hard rock seismic imaging the exploration of non hydrocarbon resources is receiving increased attention worldwide particularly in terms of renewables e g geothermal energy or minerals both resources are often bound to hard rock environments which normally exhibit a strong degree of heterogeneity including faults and fractures on all scales land seismic surveys for characterizing geothermal reservoirs and mineral deposits are therefore facing the challenge of adapting the methods and tools developed for stratified sedimentary environments to strongly scattering crystalline rocks this comprises not only the pre processing of seismic data but also the imaging steps and furthermore the description and quantification of the resulting images this special issue of geophysical prospecting contains 16 papers resulting from a workshop titled hard rock seismic imaging during the 76th eage conference exhibition 2014 in amsterdam the objective of the workshop was to address all parts of the workflow from modelling and data acquisition design over data processing and imaging to interpretation general concepts and case studies were presented and the workshop attracted a large number of participants from both industry and academia from all over the world a brief introduction to the papers included in this special issue follows divided into the two main categories of the workshop mineral exploration and geothermal prospecting interested readers are also encouraged to check the two earlier special volumes on similar topics by eaton et al 2003 and the references therein and malehmir et al 2012 and the references therein

interferometric ground roll removal attenuation of scattered surface waves in single sensor data geophysics 75 no 2 sa15 sa25 to interferometric ground roll removal attenuation of scattered surface waves in single sensor data david f halliday andrew curtis peter vermeer claudio strobbia anna glushchenko dirk jan van manen and johan o a robertsson geophysics 75 no 2 sa15 sa25

rupture dynamics and ground motion from 3 d rough fault simulations 1 we perform three dimensional 3 d numerical calculations of dynamic rupture along non planar faults to study the effects of fault roughness on rupture propagation and resultant ground motion the fault roughness model follows a self similar fractal distribution over length scales spanning three orders of magnitude from 102 to 105 m the fault is governed by a strongly rate weakening friction and the bulk material is subject to drucker prager viscoplasticity fault roughness promotes the development of self healing rupture pulses and a heterogeneous distribution of fault slip at the free surface and at depth the inelastic deformation generated by the large dynamic stress near rupture fronts occurs in a narrow volume around the fault with heterogeneous thickness correlated to local roughness slopes inelastic deformation near the free surface however is induced by the stress waves originated from dynamic rupture at depth and spreads to large distances 10 km away from the fault the present simulations model seismic wave excitation up to 10 hz with rupture lengths of 100 km permitting comparisons with empirical studies of ground motion intensity measures of engineering interest characteristics of site averaged synthetic response spectra including the distance and period dependence of the median values absolute level and intra event standard deviation are comparable to appropriate empirical estimates throughout the period range 0 1 3 0 s this class of model may provide a viable representation of the ground motion excitation process over a wide frequency range in a large spatial domain with potential applications to the numerical prediction of source and path specific effects on earthquake ground motion

geologically driven 3d modelling of physical rock properties in support of interpreting the seismic response of the lalor volcanogenic massive sulphide deposit snow lake manitoba canada 3d lithofacies and physical rock property models were generated to interpret 3d seismic data acquired over the lalor volcanogenic massive sulphide deposit manitoba canada the lithofacies model revealed that strong seismic reflectivity is associated with ore host rock and mafic felsic lithofacies contacts including their hydrothermally altered equivalents different physical rock property models were subjected to 3d seismic forward modelling using the sofi3d finite difference code seismic synthetics from discrete and interpolated models in which kriging of p wave velocity and density was conditioned by curvilinear grids conformable to the 3d modelled geological structure showed a much better match to the seismic data in comparison to those generated by kriging in cartesian space synthetics from these curvilinear grid models corroborate the origin of seismic reflectors as qualitatively inferred from the lithofacies model seismic synthetics generated from physical rock property models in which physical rock properties were augmented by densely sampled secondary variables such as feo percentage enhanced lateral continuity of seismic reflectivity although these co kriged petrophysical models were not more accurate than their kriged equivalents the physical rock property modelling methodology was also useful for testing the utility of passive interferometric seismic surveys as this highlighted the limitations of the discrete physical rock property model

3d seismic imaging of the lalor volcanogenic massive sulphide deposit manitoba canada a three component three dimensional seismic data set was acquired over the lalor volcanogenic massive sulphide deposit near snow lake manitoba canada to assess the reflectivity of the ore and further validate the potential of three dimensional reflection seismic methods for deep mineral exploration the lalor deposit was chosen as a test site as it provided an intact well characterized 25 mt deep ore deposit with a rich catalogue of geological and geophysical data as well as extensive drill core and drill hole geophysical and geological logs an analysis of physical rock properties from borehole logging data indicates that massive sulphides associated with the zincrich zones could produce prominent reflections whereas acoustic impedances of zones with disseminated gold do not sufficiently differ from the impedances of the host rocks to produce reflections the interpretation of the seismic data is constrained with a detailed three dimensional lithofacies model constructed from the categorical kriging of 15 lithological units identified in borehole intersections processing of the seismic data included prestack dip moveout and poststack time migration final images reveal some strong reflections associated with the zinc rich massive sulphide zones the most prominent reflection results from the constructive interference of thin and closely spaced massive sulphide zones and felsic mafic volcanic rock contacts above and below the mineralization contacts between felsic and mafic volcanic rocks including those that were hydrothermally altered and subsequently metamorphosed produced prominent and continuous reflections that are used to map the main architecture of the footwall rocks at depth a series of continuous and conformable reflections indicate the general geometry of the volcanic sequences in the area of the three dimensional seismic survey