bedload sediment transport dynamics in a macrotidal embayment and implications for export to the southern great barrier reef shelf abstract keppel bay is a macrotidal embayment on a tectonically stable tropical coast which links the fitzroy river with the great barrier reef continental shelf estuaries and deltas act as conduits between catchments and inner shelf environments therefore understanding sediment transport pathways in these complex systems is essential for the management of ecosystems such as coral reefs that are potentially vulnerable to enhanced river sediment loads furthermore the morphology and sediment dynamics of subtidal sand ridges and dunes are relatively poorly characterised in macrotidal estuaries particularly in turbid episodic systems such as the fitzroy river and keppel bay our sedimentological analysis of seabed samples shear stress modelling and three dimensional acoustic imaging reveals that keppel bay is a mixed wave and tide dominated estuarine system areas of sediment starvation and shoreward transport characterise the offshore zone whereas a complex of both active and relict tidal sand ridges and associated subaqueous dunes dominate the relatively protected southern keppel bay transport within this region is highly dynamic and variable with ebb dominated sediment transport through tidal channels into the outer bay where there is a switch to wave dominated shoreward transport ultimately bedload sediments appear to be reworked back inshore and to the north and are gradually infilling the bedrock defined embayment our characterisation of the keppel bay system provides a detailed example of the physiography of the seaward portion of a tide dominated system and shows that sediment transport in these areas is influenced by a variable hydrodynamic regime as well as relict channels and bedrock topography

an integrated approach to coastal erosion problems in northern tuscany italy littoral morphological evolution and cell distribution abstract occupation of the coast has significantly increased in recent decades mostly due to a greater demand for recreation and tourism today erosion threatens many human made structures and activities requiring an integrated approach for the understanding of coastal dynamics and identification of alternatives to associated problems this study investigates a 64 km long coastal physiographic unit in the northern microtidal littoral of tuscany italy vertical aerial photographs and direct field surveys were used to retrieve changes in shoreline position over 1938 1997 and 1997 2005 time intervals significant beach accretion was observed during the first period updrift of carrara 84 m and viareggio 280 m harbours and at marina di pietrasanta 100 m whereas severe erosion occurred downcoast of carrara harbour 130 m at marina dei ronchi and on the northern side of arno river mouth 400 m similar trends were observed between 1997 and 2005 beach slope between the 1997 shoreline position and the closure depth correlated well with the distribution of erosion accretion patterns from the 1938 1997 period slopes were lower in eroded areas than at sites under accretion longshore distribution of erosion accretion patterns was controlled by coastal compartmentalisation three of the main littoral cells were mostly formed by natural limits i e punta bianca promontory marina di pietrasanta the arno river mouth and the port of livorno several sub cells were created within these cells due to the introduction of human made structures such as carrara and viareggio harbours which formed artificial fixed limits that allowed the transport of sediments exclusively fines in one direction only results will help improve the understanding of coastal processes and manage littoral sediment transport in a sustainable manner this will reduce the need for structural interventions such as breakwaters and groynes which in the past decades prevented coastal retreat at local scale but shifted erosion downdrift leading to degradation of the investigated area and requiring continuous maintenance

receiver pair seismic interferometry applied to body wave usarray data with seismic interferometry reflections can be retrieved between stations positioned on the earth s surface in the classical form the reflections are retrieved by a crosscorrelation of observations and an integration over subsurface sources for a specific data set however the actual source distribution might not be sufficient to approximate the source integral yet there might be a dense distribution of receivers allowing an integration over the receiver domain we rewrite the source integral to an integration over receiver pairs and call it receiver pair seismic interferometry rpsi with this formulation reflections can be retrieved even in the limiting case of only a single source we illustrate the new relation both with synthetic data and data from the usarray which is a large grid of stations covering the usa the field observations are from an earthquake in mexico we show that rpsi can be applied both for a line and grid of receivers when using isolated phases recorded over a line of stations inline with the earthquake reflections are retrieved from the core mantle boundary which reflections can be ascribed to specific virtual source and receiver locations within the usarray when using full responses as input to rpsi the retrieved phases are an average over multiple virtual sources and receivers location is then only possible when the integrand is spatially windowed or when a clear leading term is identified when using a grid of receivers the location of the source does not need to be known but spatially averaged instead of localized responses are obtained also when isolated arrivals are used as input to rpsi

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

a temporal change of shear wave anisotropy within the marine sedimentary layer associated with the 2011 tohoku oki earthquake 1 we found persistent reflections of s waves from the bottom of a 350 m thick marine sedimentary layer on the outer rise of the japan trench just to the east of the source area of the 2011 great tohoku oki earthquake mw9 0 by auto correlating ambient seismic noise recorded on 1 year continuous records of broadband ocean bottom seismometers the two way travel times of reflected s waves which vary as a function of the polarization direction indicate a velocity anisotropy of 1 7 in the sedimentary layer the fast direction is estimated to be trench parallel possibly due to cracks or normal faults formed by bending of the plate in the outer rise the travel time also shows a coseismic velocity reduction of 2 with slightly reduced anisotropy within the layer the change gradually recovered to pre earthquake conditions through 4 months after the earthquake although recovery was not complete during the period of the observation we also detected a similar anisotropic structure and magnitude of coseismic velocity reduction in this layer based on s coda of earthquakes with magnitudes greater than 5 0 such coseismic changes can be explained either by increases of crack density and crack sphericity within the suddenly stressed sedimentary layer or by channeling and networking of water flow in the strongly shaken sedimentary layer

temporal changes of subsurface velocities during strong shaking as seen from seismic interferometry 1 we apply a deconvolution method to a strong motion data set recorded at the surface and in boreholes in northeast honshu japan we try to characterize the nonlinear effects of the subsurface soil during strong shaking and show the change of the subsurface velocity structure during the shaking the deconvolved waveforms reflect the subsurface velocity structure and their horizontal and vertical components correspond to s and p wave respectively traveling from the borehole to the ground surface the strong motion records with smaller values of peak acceleration do not include significant nonlinear effects so the deconvolved waveforms of the observed accelerations can be well simulated by the program shake91 for high acceleration motions during the shaking of two separate earthquakes large reductions of near surface velocities are seen in results for the 2008 iwate miyagi nairiku earthquake the large high frequency ground motions over 4g at one near source station caused a nonlinear response of the soil and the reduction of the average shear wave velocity reached 24 this corresponds to a stiffness change of over 75 the soil properties and the stiffness coefficient which changed during the shaking did not fully recover after the shaking leaving a static change

evaluation of depth of closure using data from duck nc usa using 12 years of frequent high precision profiles collected on a wave dominated sandy oceanic beach to 8 m depth the characteristics and interpretation of depth of closure or the seaward limit of significant profile change is critically examined this includes evaluation of the predictive capability of d1 the seaward boundary of the littoral zone as originally defined by hallermeier 1981 hallermeier r j 1981 a profile zonation for seasonal sand beaches from wave climate coastal eng 4 253 277 depth of closure during major erosional events is usually produced by the seaward limit of offshore bar movement following the original recommendation of hallermeier 1981 d1 based on 12 h exceeded wave height and a reference depth of mean low water provides a robust limit to the observations using a 6 cm change criterion empirically the observed depth of closure is 69 of d1 although the scatter is large this scatter is partly controlled by pre event profile shape most particularly bar configuration depth of closure under accretional conditions can also be measured but it is time scale dependent as accretion is a slow steady process d1 underpredicts closure for accretional situations time interval e g annual depth of closure represents the integral effect of erosional and accretional events an important observation of the data is that depth of closure increases with time scale however the full population of time interval observations is not resolved at duck due to the measurement limit 8 m depth as time interval increases from 1 year to 8 years less cases close most non closing time interval cases coincide with the periods influenced by the most energetic wave events however time interval closures are generally deeper than the biggest event closure in the period showing that it represents more than the largest event the frequency distribution of the data suggests that most if not all of these missing data simply represent closures deeper than 8 m depth up to a 4 year time interval d1 t appears to provide a reasonable limit to the quantified observations it is an interesting result that d1 an event based approach might provide a limit to closure over periods up to 4 years as these time interval closures are generally larger than those produced by single storms therefore the general applicability of this result for more complete data sets or on rapidly evolving i e eroding or accreting coasts is uncertain the present data also suggest that on swell dominated coastlines where accretional processes are dominant d1 may underpredict closure suggesting an important limitation to this approach but as sediment would be moving onshore this may not be a practical problem therefore within the limits of the data set hallermeier s 1981 approach is found to define robust estimates of depth of closure particularly for individual erosional events this useful result is expected to find widespread application in coastal geology and engineering

differential stress strain rate and temperatures of mylonitization in the ruby mountains nevada implications for the rate and duration of uplift kno ledge of the m agnitude of the differential stress during the formation of mylonitic rocks provides constramts on mechanical and thermal models for the exhumation of the metamorphosed footwalls of major low angle detachment faults we have analyzed the differential flow stress during the mylonitization of quartzose rocks in the ruby mountains nevada using grain size piezometers and kinetic laws for grain g owth quartzites from mylonitic shear zones in lamoille canyon and secret creek gorge have grain sizes of 91 151 m and 42 64 m respectively the peak temperature during mylonitization was 630 i 50 c and analysis of grain growth kinetics indicates that mylonitization continued during cooling to temperatures s450 c quartz grain size piezometers suggest that the mylonitization occurred under differential stresses crl cr3 of 38 64 mpa or maximum shear stresses of 19 32 mpa extrapolation of quartzite flow laws indicates that the mylonitization occurred at strain rates between 10 10 and 10 13 1 arguments presented m the paper suggest that the likely range of strain rates is 10 11 to 10 12 1 these strain rates are compatible with displacement rates of the order of 23 mm yr l along a 1 5 km thick simple shear zone such a shear zone dipping 15 would produce an uplift rate of 5 8 km m y 1 and a horizontal extensioo rate of 22 km m y l this uplift rate indicates that midcrustal mylonitic rocks could have been lifted up along a 1 5 km thick simple shear zone dipping 15 in 2 6 m y

dynamic development of fault rocks in a crustal scale detachment an example from western norway 1 the nordfjord sogn detachment nsd zone of western norway juxtaposes eclogites and gneisses of lower crustal affinity with sedimentary deposits suggesting that the zone experienced substantial displacement during devonian extensional denudation of the caledonides renewed activation occurred in permian and jurassic cretaceous times the detachment zone consists of a succession of fault related rocks reflecting various crustal positions and deformation mechanisms during activation and unroofing in more detail the lower 1 2 km thick section of the nsd zone consists of mylonites with various protoliths showing a general upward decrease in metamorphic grade the mylonitic section is truncated by the nsd fault defining the boundary toward hanging wall nappe rocks that are topped by sedimentary basins in an attempt to provide precise descriptions of the observed fault rocks we classify these rocks into 1 noncohesive breccias 2 cemented and indurated breccias of secondary cohesion and 3 cataclasites phyllonites and mylonites formed with primary cohesion along and across strike sections of the fault reveal the spatial and temporal relationships of the nsd fault the fault zone consists of a lower section of phyllonites and cataclasites reaching a total thickness of 50 70 m significant volumes of pseudotachylyte were injected into these fault rocks and were later reworked reactivation of the fault is suggested by overprinting carbonate cemented breccias that are cut by a discrete fault itself associated with breccias and gouge by comparing the various fault rocks and their formation mechanisms some constraints can be applied to the unroofing history the nsd fault developed in the ductile brittle transition zone of the crust where it experienced an initial shift from mainly frictional to plastic flow caused by reaction softening before hardening caused a return to frictional flow at the same time repeated pulses of pseudotachylyte were generated possibly lubricating the fault zone and contributing to strain localization these pseudotachylyte pulses also show that the fault was affected by seismic slip events before returning to a creep regime within a wider section than that ruptured by earthquakes younger cemented breccias and noncohesive breccias and gouge reflect earthquake rupturing and frictional flow within the seismogenic crust

deep water subsurface imaging using obs interferometry abstractseismic interferometry processing is applied to an active seismic survey collected on ocean bottom seismometers obs deployed at 900 m water depth over a carbonate hydrates mound in the gulf of mexico common midpoint processing and stacking of the extracted green s function gives the subsurface pp reflectivity with a horizontal resolution of half the receiver spacing the obtained seismic section is comparable to classical upgoing downgoing wavefield decomposition and deconvolution applied on a common receiver gather seismic interferometry does not require precise knowledge of source geometry or shooting times but more accurate results are obtained when including this information for segmenting the signals before the crosscorrelations especially when signals from distant surveys are present in the data reflectivity estimates can be obtained with the crosscorrelation of pressure or vertical particle velocity signals but the pressure data gives the best resolution due to the wider frequency

seismic velocity anisotropy of phyllosilicate rich rocks characteristics inferred from experimental and crack model studies of biotite rich schist summary seismic velocity anisotropy of biotite schist 30 per cent mode biotite was measured under confining pressures up to 150 mpa the rock shows weak orthotropy which was altered from transverse isotropy ti generated by biotite preferred orientation the orthotropy was caused by microfolding in the rock the velocity increase under confining pressure indicates that most crack planes are aligned parallel to the cleavage planes silicate sheet of the oriented biotite minerals the anisotropy of the rock is basically ti due to both the aligned biotite minerals and cracks which have a common symmetry axis we found that other sheet silicate rich rocks have a similar anisotropy with the biotite schist in which the ti type anisotropy is characterized by the slow p and s wave velocities along the symmetry axis this is caused by the preferred orientation of sheet silicate minerals and the extremely slow p and s wave velocities along the axis perpendicular to the silicate sheet compared to the directions along the silicate sheet when rock contains a large percentage of highly oriented sheet silicates the fast and slow shear waves exchange their polarities at some off symmetry axis directions indicating that the qswave quasi s wave velocity exceeds the sh wave velocity the phase velocity distribution of qs wave shows an asymmetry with respect to the angle from the symmetry axis which is characterized by a bulge in this distribution located near the symmetric axis this is inherent to most sheet silicate minerals when crack density of aligned cracks increases the p wave velocity along the symmetry axis decreases considerably the qs wave phase velocity in the off axis directions also decreases in accordance with the decrease of the p velocity along the symmetry axis the asymmetry of the qs wave phase velocity distribution increases as the p wave velocity decreases along the symmetry axis this relationship can be well understood by means of berryman s extended thomsen approach

using ambient noise seismic interferometry and local and teleseismic earthquakes to determine crustal thickness and moho structure of the northwestern gulf of mexico margin

pliocene pleistocene coastal events and history along the western margin of australia coastal deposits along the western coastal margin of australia a region of relative tectonic stability record plio pleistocene events and processes affecting the inner shelf and adjacent hinterland tectonic deformation of these deposits is more apparent in the carnarvon basin and rather less so in the perth basin the most complete record comes from the perth basin where units of pliocene and pleistocene ages are well represented in the perth basin the predominantly siliciclastic yoganup formation ascot formation and bassendean sand represent a complex of shoreline inner shelf and regressive dune facies equivalents the deposition of which began at an undetermined stage of the pliocene through to the early pleistocene the deposition of this sequence closed with a major regression and significant faunal extinction bioclastic carbonates characterize the middle and late pleistocene of the perth and carnarvon basins fossil assemblages include a distinct subtropical element unknown from the ascot formation and suggesting a strengthening of the leeuwin current the estuarine arcoid bivalve anadara trapezia characterizes assemblages of oxygen isotope stages 5 and 7 in the perth and carnarvon basins where it is now extinct deposits of substage 5e perth basin also record a southerly expansion of warm water corals and other fauna consistent with shelf temperatures warmer than present new uranium series ages on corals from marine sequences of the tantabiddi member of the bundera calcarenite of the western cape range are consistent with the double peak hypothesis for levels of substage 5e but the evidence remains less than conclusive initial uranium series dates from the bibra and dampier formations of shark bay indicate that both derive from the late pleistocene these numerical ages contradict previous interpretations of relative ages obtained from field studies the age relationship of the units requires further investigation

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

evolution of caledonian deformation fabrics under eclogite and amphibolite facies at vardalsneset western gneiss region norway the vardalsneset eclogite situated in the western gneiss region sw norway is a well preserved tectonite giving information about the deformation regimes active in the lower crust during crustal thickening and subsequent exhumation the eclogite constitutes layers and lenses variably retrograded to amphibolite and is composed of garnet and omphacite with varying amounts of barroisite actinolite clinozoisite kyanite quartz paragonite phengite and rutile the rocks record a five stage evolution connected to caledonian burial and subsequent exhumation 1 a prograde evolution through amphibolite facies t 490 63 c is inferred from garnet cores with amphibole inclusions and bell shaped mn profile 2 formation of l s tectonite eclogite t 680 20 c p 16 2 kbar related to the subduction of conti nental crust during the caledonian orogeny lack of asymmetrical fabrics and orientation of eclogite facies extensional veins indicate that the deformation regime during formation of the l s fabric was coaxial 3 formation of sub horizontal eclogite facies foliation in which the finite stretching direction had changed by approximately 90 disruption of eclogite lenses and layers between symmetric shear zones characterizes the dominantly coaxial deformation regime of stage 3 locally occurring mylonitic eclogites t 690 20 c p 15 1 5 kbar with top w kinematics may indicate however that non coaxial deformation was also active at eclogite facies conditions 4 development of a widespread regional amphibolite facies foliation t 564 44 c p 10 3 8 1 kbar quartz veins and development of conju gate shear zones indicate that coaxial vertical shortening and sub horizontal stretching were active during exhumation from eclogite to amphibolite facies conditions 5 amphibolite facies mylonites mainly formed under non coaxial top w movement are related to large scale movement on the extensional detachments active during the late orogenic extension of the caledonides the structural and metamorphic evolution of the vardalsneset eclogite and related areas support the exhumation model including an extensional detachment in the upper crust and overall coaxial deformation in the lower crust

virtual shear source makes shear waves with air guns we demonstrate a novel application of the virtual source method to create shear wave sources at the location of buried geophones these virtual downhole sources excite shear waves with a different radiation pattern than known sources they can be useful in various shear wave applications here we focus on the virtual shear check shot to generate accurate shear velocity profiles in offshore environments using typical acquisition for marine walkaway vertical seismic profiling vsp the virtual source method is applied to walkaway vsp data to obtain new traces resembling seismograms acquired with downhole seismic sources at geophone locations thus bypassing any overburden complexity the virtual sources can be synthesized to radiate predominantly shear waves by collecting converted wave energy scattered throughout the overburden we illustrate the concept in a synthetic layered model and demonstrate the method by estimating accurate p and s wave velocity profiles below salt using a walkaway vsp from the deepwater gulf of mexico

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

sediment transfer from beach to shoreface the sediment budget of an accreting beach on the danish north sea coast abstract the sediment budget along the southern part of the exposed danish north sea coast was assessed through a combination of cross shore profile analysis numerical modeling and field measurements of cross shore and longshore sediment transport at the boundary between the upper and the lower shorefaces the beaches along this coast are accreting but observed sediment storage is far smaller than sediment supplied by southerly directed wave driven currents the excess sediment volumes are transferred seaward across the shoreface by systematically offshore migrating nearshore bars that deliver sediment to the lower shoreface from where it is eventually removed by northward directed wind generated currents in the geological past sediment storage rates were much larger than at present and it is likely that the rate of storage along this coastline decreased as shoreface geometry adjusted towards equilibrium associated with shoreface steepening

widespread seagrass meadows during the early miocene burdigalian in southwestern australia paralleled modern seagrass distributions abstract the trealla limestone which forms a veneer of foraminiferal rich limestone and covers over 4000 km2 of the tectonically stable southern carnarvon platform contains the oldest evidence for seagrass meadows known in western australia it belongs to lower tf1 letter stage based on larger benthic foraminifers of the burdigalian within interval 19 16 ma and is the only miocene unit on the platform the trealla limestone here is coeval to the deeper water lower part of the much thicker trealla limestone in the exmouth sub basin to the northwest a seagrass meadow depositional environment is indicated by most of the studied microfacies based on comparisons with modern sediment composition and foraminiferal assemblages found in innermost shelf seagrass banks between 23 s and 32 s on the present western australian coast some levels in the trealla limestone on the platform e g with abundant miliolid foraminifers and absence of coral debris probably were deposited in and around dense seagrass meadows similar to those present today in the metahaline 40 55 ppt salinity reaches of shark bay whereas other levels e g coral floatstone were deposited under normal marine conditions based on comparisons with modern carbonate sediment and biota in the region the biogenic composition of the trealla limestone on the platform suggests winter minimum sea surface temperatures within the range of 17 22 c the nullabor limestone in the eucla basin at 10 further south on the southern australian margin is similar at least in part in composition and age to the trealla limestone on the southern carnarvon platform both may have been deposited during a burdigalian sea level rise and during part of the miocene climate optimum recognized elsewhere sediment composition and foraminiferal assemblages including epiphytic types found in the trealla and nullabor limestones are similar to those in the modern seagrass banks of the region this suggests that seagrasses similar to the extensive posidonia and amphibolus stands which are dominant today between 25 s and 35 s along the western australian coast were widespread during the burdigalian

hydrodynamics and sedimentation in wave dominated coastal environmentsshoreface morphodynamics on wave dominated coasts an open ocean shoreface typical of long wave dominated sandy coasts has been examined through a combination of extensive field measurements of wave and current patterns with computations of marine bedload transport and sedimentation sand transport on the upper shoreface is dominantly controlled by waves with only secondary transport by currents sand on the middle and lower shoreface as well as the inner continental shelf is entrained by storm waves and transported by a complex pattern of bottom boundary layer currents storm events have been studied and modeled for the shoreface off tiana beach long island the dominant effect of coastal frontal storms is to cause significant shore parallel bedload transport with important shore normal secondary components these storms tend to result in net offshore transport of sand removed from the beach and surf zone systems the bedload transport during a storm is convergent on the shoreface leading to accretion most accretion occurs on the upper shoreface with lesser deposits covering the middle and lower shoreface as well as the inner continental shelf longer term equilibrium can be maintained by slow return of sand up the shoreface during non storm conditions annual and geologic time scale budgets of shoreface sand transport and sedimentation yield equilibrium net accretion or net deposition the annual balance results from an integration of the event scale bedload transport patterns and morphologic responses these processes and responses have feedback mechanisms which stabilize the system over longer but not geologic time scales geologic time scale balances are controlled by relative sea level changes and relative availability of sediment supply with the event scale shoreface and transporting processes providing the mechanism to produce the changes in long term morphology and sedimentation patterns in the area of study the long term pattern is one of net shoreface erosion and the permanent loss of sand to the shelf floor

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

inter source body wave propagations derived from seismic interferometry summary seismicinterferometrycombinedwithsource receiverreciprocityhasrecentlybeenemployed to extract inter source wave propagations in this study we applied the technique to seismograms of earthquakes that occurred at depths of 300 500 km beneath the bonin islands the wavelets of direct p and s waves generated by the deep earthquakes were examined to compute cross correlation functions ccfs we stacked the ccfs observed at receivers around the stationary point whose location could be estimated by the ray tracing technique because the phases in such ccfs potentially emerge at similar lag times that is the stationary phases the results demonstrate the retrieval of direct p and s waves propagating between pairs of deep earthquakes in particular direct p waves are reconstructed for most event pairs the following points should be considered to effectively retrieve the propagation of body waves 1 it is important to design a geometry in which the stationary phase derived from two earthquakes can be observed at the employed stations 2 the lag time difference of the stationary phases that emerge in the employed ccfs should be as small as possible and 3 the direct waves associated with deep earthquakes have a large amplitude at stations employed for cross correlation which is accomplished by both low noise level at the stations and the radiation pattern of the sources

landform characterization using geophysics recent advances applications and emerging tools abstract this paper presents an overview of the strengths and limitations of existing and emerging geophysical tools for landform studies the objectives are to discuss recent technical developments and to provide a review of relevant recent literature with a focus on propagating field methods with terrestrial applications for various methods in this category including ground penetrating radar gpr electrical resistivity er seismics and electromagnetic em induction the technical backgrounds are introduced followed by section on novel developments relevant to landform characterization for several decades gpr has been popular for characterization of the shallow subsurface and in particular sedimentary systems novel developments in gpr include the use of multi offset systems to improve signal to noise ratios and data collection efficiency amongst others and the increased use of 3d data multi electrode er systems have become popular in recent years as they allow for relatively fast and detailed mapping novel developments include time lapse monitoring of dynamic processes as well as the use of capacitively coupled systems for fast non invasive surveys em induction methods are especially popular for fast mapping of spatial variation but can also be used to obtain information on the vertical variation in subsurface electrical conductivity in recent years several examples of the use of plane wave em for characterization of landforms have been published seismic methods for landform characterization include seismic reflection and refraction techniques and the use of surface waves a recent development is the use of passive sensing approaches the use of multiple geophysical methods which can benefit from the sensitivity to different subsurface parameters is becoming more common strategies for coupled and joint inversion of complementary datasets will once more widely available benefit the geophysical study of landforms three cases studies are presented on the use of electrical and gpr methods for characterization of landforms in the range of meters to 100 s of meters in dimension in a study of polygonal patterned ground in the saginaw lowlands michigan usa electrical resistivity tomography was used to characterize differences in subsurface texture and water content associated with polygon swale topography also a sand filled thermokarst feature was identified using electrical resistivity data the second example is on the use of constant spread traversing cst for characterization of large scale glaciotectonic deformation in the ludington ridge michigan multiple cst surveys parallel to an 60 m high cliff where broad 100 m synclines and narrow clay rich anticlines are visible illustrated that at least one of the narrow structures extended inland a third case study discusses internal structures of an eolian dune on a coastal spit in new zealand both 35 and 200 mhz gpr data which clearly identified a paleosol and internal sedimentary structures of the dune were used to improve understanding of the development of the dune which may shed light on paleo wind directions

exhuming norwegian ultrahigh pressure rocks overprinting extensional structures and the role of the nordfjord sogn detachment zone 1 the nordfjord sogn detachment zone nsdz is widely cited as one of the primary structures responsible for the exhumation of norwegian ultra high pressure uhp rocks here we review data from the considerable volume of research describing this shear zone and compile a strikeparallel cross section along the nsdz from the solund basin in the south to the soroyane uhp domain in the north this cross section highlights several previously unrecognized patterns revealing a shear zone with top to the west asymmetric fabrics that 1 initiated at amphibolite facies 2 overprints metamorphic breaks and tectonostratigraphic contacts and 3 has a gradational continuum of muscovite cooling ages these patterns constrain the kinematic evolution of the nsdz and suggest a new three step model for the exhumation of norwegian u hp rocks the initial stages of exhumation were characterized by the rise of crustal rocks from u hp depths to the base of the crust by buoyancydriven mechanisms not specified in this paper mantle exhumation was followed by top to thewest normal sense displacement within a broad noncoaxial ductile shear zone near the base of the crust that overprinted tectonostratigraphic contacts formed previously during mantle exhumation in the final stages of crustal exhumation top w brittleductile detachments soled into and partially excised this ductile shear zone dropping the devonian basins into contact with rocks of varying tectonostratigraphic levels this new interpretation of the nsdz is significant as it accounts for the extreme crustal excision observed in western norway using three sequentially overprinting structures active at different stages of uhp rock exhumation citation johnston s m b r hacker and t b andersen 2007 exhuming norwegian ultrahigh pressure rocks overprinting extensional structures and the role of the nordfjord sogn detachment zone tectonics 26 tc5001

shoreface morphodynamics on wave dominated coasts abstract an open ocean shoreface typical of long wave dominated sandy coasts has been examined through a combination of extensive field measurements of wave and current patterns with computations of marine bedload transport and sedimentation sand transport on the upper shoreface is dominantly controlled by waves with only secondary transport by currents sand on the middle and lower shoreface as well as the inner continental shelf is entrained by storm waves and transported by a complex pattern of bottom boundary layer currents storm events have been studied and modeled for the shoreface off tiana beach long island the dominant effect of coastal frontal storms is to cause significant shore parallel bedload transport with important shore normal secondary components these storms tend to result in net offshore transport of sand removed from the beach and surf zone systems the bedload transport during a storm is convergent on the shoreface leading to accretion most accretion occurs on the upper shoreface with lesser deposits covering the middle and lower shoreface as well as the inner continental shelf longer term equilibrium can be maintained by slow return of sand up the shoreface during non storm conditions annual and geologic time scale budgets of shoreface sand transport and sedimentation yield equilibrium net accretion or net deposition the annual balance results from an integration of the event scale bedload transport patterns and morphologic responses these processes and responses have feedback mechanisms which stabilize the system over longer but not geologic time scales geologic time scale balances are controlled by relative sea level changes and relative availability of sediment supply with the event scale shoreface and transporting processes providing the mechanism to produce the changes in long term morphology and sedimentation patterns in the area of study the long term pattern is one of net shoreface erosion and the permanent loss of sand to the shelf floor

maintenance of the shoreface by wave orbital currents and mean flow observations from the long island coast waves and currents were observed for a total of 36 days in august 1976 and 1977 calculations of wave transport of sediment using a bagnold equation for transport and second order stokes theory show that wave orbital current asymmetry results in landward sediment transport in 10 m or less water depth but does not significantly effect transport at greater depths calculations of sand transport using the madsen grant formulation show that during a 36 day observation period sediment in less than 10 m of water generally moved landward into the breaker and then along coast with the wave driven littoral flow the calculations show that below 10 m the generally upwelling coast parallel mean flow did not move sediment however during two days of a mild summer northeaster storm a downwelling coastal jet developed with 60 cm sec sup 1 maximum current the calculations show that if this flow had been combined with the intense wave regime of the succeeding several days sediment would have been entrained across the lower as well as the upper shoreface movement would have been offshore and alongshore such storm transport is believed to be typical of the more intense winter storms and to be responsible for the erosionalmore shoreface retreat that has caused up to a kilometer of shoreline retreat on the long island coast in the last century less

carbonate sediment dynamics and compartmentalisation of a highly modified coast geraldton western australia abstract the coastal zone off geraldton in temperate midwestern australia was investigated to identify sediment dynamics and sediment budget components of two main embayments an integrated analysis of hydrodynamics geomorphology sediments and habitat data was required to overcome a lack of previous examinations of sediment dynamics in the region the seaward extent of the nearshore transport system was assessed an improved understanding of coastal sediment dynamics and its relationship to coastal stability and assets was also achieved the system is complex with biogenic sediment input as well as carbonate dune and river derived sediments coastal erosion at geraldton is mitigated by nourishment activities which require sand bypassing natural and artificial sediment sinks were identified and are mainly located in the northern embayment where beach erosion is more significant a dredged shipping channel needed to provide access to port facilities modifies the local sediment dynamics this study provides new information for managing the geraldton coast which may be applicable to similar regions of western australia and carbonate coasts elsewhere

seismicity and casing failures due to steam stimulation in oil sands this paper describes observations of seismicity and casing failures associated with steam stimulation operations at imperial oil ltd s cold lake oil field in alberta canada a total of 11 oil producing pads were monitored over a 1 2 year period using 3 component geophones cemented at depths ranging from 160 m to 400 m and data acquisition systems with a flat frequency response up to 1 5 khz most of the seismicity was detected during the steaming operations and was located in the formation overlying the oil bearing layer some activity was observed in the shales above however the reservoir itself showed almost no evidence of seismicity the estimated seismic moment of the observed events was in the range 105 107 n m 2 7 m 1 3 according to a theoretical model talebi et al 1998 and in situ observations the seismic source corresponding to casing failure events should be well described by a dipole registering seismic moment in the order of 2 106 n m seismic signals of a total of four observed casing failures were analyzed the partial failures produced seismic moments slightly lower than this value while total failures were stronger by about one order of magnitude the use of the sv sh amplitude ratio in conjunction with accurate source locations provided a robust technique for the detection of casing failures

damage detection of a building caused by the 2011 tohoku oki earthquake with seismic interferometry we apply seismic interferometry based on deconvolution to earthquake data observed in a building at tokyo metropolitan university to extract building response and estimate velocities and frequencies of traveling waves inside the building the building is a 10 story reinforced concrete structure in tokyo japan the earthquake data were recorded 2 months before 6 months after and 16 months after the m w 9 0 tohoku oki earthquake 11 march 2011 the observation period of each acquisition was 20 30 days we analyze more than 300 earthquakes recorded in these time periods and we find significant reduction 20 in wave velocities and fundamental mode frequencies after the tohoku oki earthquake because deconvolution interferometry separates the response of the building from the effect of complicated wave propagation outside the building we interpret that this reduction is mostly related to the building we can also estimate frequencies of the fundamental mode from observed data and these frequencies contain the responses of building and the ray paths from hypocenters therefore as we find from the data the frequencies estimated from observed data are generally lower than those from deconvolved waveforms due to the effects of wave propagation although the velocities in the building decrease 20 after the tohoku oki earthquake we cannot find significant reduction in the s wave velocities at the near surface depth shallower than 100 m this fact indicates the decrease in velocities is mainly related to the building and hence with deconvolution interferometry we can detect damages to the building caused by the tohoku oki earthquake

downhole receiver function a case study receiver function is defined as the spectral ratio of the radial component and the vertical component of the ground motion it is used to characterize converted waves we extend the use of the receiver function to downhole data using waves recorded in a borehole excited by an earthquake of magnitude 4 0 near san fran cisco california on 26 june 1994 the focal depth of the event was 6 6 km and the epicenter was located at a distance of 12 6 km from the borehole array six three component sensors were located at different depths in a borehole to extract a co herent response of the near surface from the incoherent earthquake waves we de convolve the waves recorded by the sensors at different depths with the waves recorded by the sensor on the surface deconvolution applied to the waves in the s time window recorded by the radial component result in an upgoing and adowngoing wave propagating with s wave velocity for the waves in the p time window re corded by the radial component deconvolution also gives an upgoing and a down going wave propagating with s wave velocity this interesting result suggests a p to s conversion at a depth below the deepest sensor to diagnose this we compute the receiverfunction forthe borehole recording of the earthquakewaves thereceiver function shows an upgoing wave with an arrival close to time t 0 for the deepest sensor the agreement of the upgoing wave in the receiver function with the travel time curve for the p to s converted wave calculated using the p and the s wave velocity profile supports the hypothesis of a pronounced p to s conversion we present a synthetic example to illustrate that the first arrival of the receiver function applied to borehole data gives the upward propagating p to s converted wave to corroborate the observation of the mode conversion we apply receiver function to a different earthquake data recorded by the same borehole array in 1998 the focal depth of the event was 6 9 km and the epicenter was located at a distance of 13 km from the borehole array the receiver function for these data also show an upgoing wave with a pulse close to time t 0 at the deepest sensor the moveout of the upgoing wave agrees with the travel time curve for the p to s converted wave hence supporting our observation of the mode conversion

feasibility of borehole ambient noise interferometry for permanent reservoir monitoring the analysis of seismic ambient noise acquired during temporary or permanent microseismic monitoring campaigns e g improved enhanced oil recovery monitoring surveillance of induced seismicity is potentially well suited for time lapse studies based on seismic interferometry no additional data acquisition required ambient noise processing can be automatized to a high degree and seismic interferometry is very sensitive to small medium changes thus there is an opportunity for detection and monitoring of velocity variations in a reservoir at negligible additional cost and effort data and results are presented from an ambient noise interferometry study applied to two wells in a producing oil field in romania borehole microseismic monitoring on three component geophones was performed for four weeks concurrent with a water flooding phase for improved oil recovery from a reservoir in ca 1 km depth both low frequency 2 hz 50 hz p and s waves propagating through the vertical borehole arrays were reconstructed from ambient noise by the virtual source method the obtained interferograms clearly indicate an origin of the ambient seismic energy from above the arrays thus suggesting surface activities as sources it is shown that ambient noise from time periods as short as 30 seconds is sufficient to obtain robust interferograms sonic log data confirm that the vertical and horizontal components comprise first arrivals of p wave and s waves respectively the consistency and high quality of the interferograms throughout the entire observation period further indicate that the high frequency part up to 100 hz represents the scattered wave field the temporal variation of apparent velocities based on first arrival times partly correlates with the water injection rate and occurrence of microseismic events it is concluded that borehole ambient noise interferometry in production settings is a potentially useful method for permanent reservoir monitoring due to its high sensitivity and robustness

human impacts in an urban port the carbonate budget otago harbour new zealand abstract otago harbour is a long 23 km narrow mean width 2 km shallow mean water depth 4 5 m tidal inlet covering 46 km 2 on the southeast coast of south island new zealand 45 50 s 170 35 e development of the city of dunedin pop 125 000 and its associated port at port chalmers has been associated with extensive dredging land reclamation and shoreline construction here we develop a carbonate sediment budget for otago harbour with limits defined at mean high water spring and the harbour entrance from the water air interface to a few cm below the sediment water interface carbonate is added to this system primarily by in situ production 10 000 tonnes caco 3 y 1 and by transport though the harbour entrance from the longshore system 24 000 tonnes caco 3 y 1 shellfishing 2 tonnes caco 3 y 1 dredging 18 000 tonnes caco 3 y 1 and early sea floor processes such as abrasion and dissolution 2000 tonnes caco 3 y 1 remove carbonate from the system the present day carbonate budget results in 14 000 tonnes caco 3 y 1 sediment storage equivalent to 0 14 mm y 1 accumulation two thousand years ago the budget would have had nearly the same inputs but many fewer outputs potentially resulting in storage twice what it is today projected increases in human impacts suggest that carbonate storage may end within 100 years carbonate storage in sediments has a role in preserving environmental information and sequestering carbon but the major value of a budget model is in clarifying the importance of human impacts urban harbours are not in a natural state and increasing human activity both locally and globally affects their overall health

a budget of carbonate framework and sediment production kailua bay oahu hawaii abstract sediments of the bay and coastal plain of kailua oahu hawaii are 90 biogenic carbonate produced by destruction of primary reef framework coral and encrusting coralline algae and by direct sedimentation through the biological activity of calcifying organisms the green alga halimeda the branching coralline alga porolithion gardineri molluscs and benthic foraminifera field measurements of benthic community structure gross carbonate production bioerosion and direct sedimentation in 17 physiographic zones in kailua bay are used to calculate modern calcareous sediment production rates in the 12 km2 fringing reef system total gross carbonate productivity by corals and encrusting coralline algae based on mapped percent cover and known growth rates occurs at an average rate of 1 22 0 36 kg m 2 y 1 over hard substrates of the reef platform corresponding to 0 8 0 2 mm y 1 using a bulk density of 1 48 g cm 3 the average of coral and coralline algae coralline algae contributes 42 of the total gross productivity bioerosion of coral and coralline algae facies at and near the reef surface estimated from slabbed reef samples occurs at average rates of 0 10 1 15 kg m 2 y 1 and releases 1 911 436 m3 of unconsolidated carbonate sediment annually mechanical erosion coral breakage likely contributes an additional 315 m3 y 1 carbonate sediment is also produced directly by the green alga halimeda branching coralline algae molluscs and benthic foraminifera at a combined rate of 1 822 200 m3 y 1 using densities specific to sediment origin the total rate of production of unconsolidated carbonate sediment in kailua bay is the sum of these sources amounting to 4 048 635 m3 y 1 normalizing gross sediment production in kg y 1 by reef habitat area in m2 generates average rates of productivity in kg m 2 y 1 that are directly comparable to each other and to the literature such rates can also be employed and tested in other reef settings in kailua bay the total production of calcareous sediment corresponds to an average normalized rate of 0 53 0 19 kg m 2 y 1 with 0 33 0 13 kg m 2 y 1 contributed through erosion of the coralgal framework and 0 20 0 06 kg m 2 y 1 contributed by direct sediment production on the reef surface applying these modern sediment production rates over the 5 000 years that kailua bay has been completely inundated by postglacial sea level rise an estimated 20 2 3 2 106 m3 of unconsolidated carbonate sediment has been produced in the system the volume of sediment stored in the various reef channels and holes in kailua bay is 3 7 0 3 106 m3 or 19 of that produced since 5 000 y bp the volume of sand in the modern beach is 1 0 0 1 106 m3 or 5 of holocene sediment production the volume of carbonate sediment stored in the coastal plain is estimated using core log data and associated radiocarbon ages to be 10 0 1 8 106 m3 or 51 of holocene sediment production the remaining 25 likely represents sediment loss due to the natural processes of dissolution attrition and transport offshore these export terms are not well understood and emphasize the need for sediment dynamics to be incorporated into reef and sediment budgets although sediment production in this reef system is prodigious the rate of new sediment supplied to the beachface is less than 2 of what moves on and off the beach seasonally

a shallow seismic velocity model for the groningen area in the netherlands the province of groningen in the netherlands holds one of the world s largest natural gas fields and it has been an important source of energy for western europe for many decades the seismicity in recent years called for a better understanding of the local subsurface and therefore a dense network of 70 boreholes was installed in early 2015 each borehole is equipped with four geophones and a surface accelerometer in this study data from this network are used to determine the shallow velocity structure that is important for the quantification of the seismic hazard and accurate source localizations compressional and shear wave velocity profiles with uncertainties are derived for each of the 200 m deep boreholes using passive seismic interferometry applied to local event data the resulting seismic velocity distributions are presented as contour maps for 50 m depth intervals the maps show strong lateral variations where areas of low vp vs ratio correspond to regions of sedimentary infill the shear wave velocities were derived using the transverse component seismograms because the sensor orientations of the borehole geophones were unknown they had to be determined first this was done using a novel method based on cross correlations between the geophones and their colocated surface accelerometer in addition by extensive cross correlation analysis over the network several installation inconsistencies were identified and resolved

beach and nearshore facies southeast australia abstract the morphology texture and facies sequence on seven sand beaches located in low moderate and high wave energy microtidal environments in southern australia were investigated using box coring and scuba observations systematic variation in facies occur both within and between the beaches low energy reflective beaches are limited in lateral and vertical extent and in facies to beach laminations separated by coarse step deposits from finer nearshore cross lamination facies moderate energy intermediate beaches characterised by rip circulation possess increasingly wider surfzones with ridge and runnel and bar trough facies separating the beach and step facies from the more extensive nearshore sequence high energy dissipative beaches may have 500 m wide surfzones containing multiple bar trough topography fine beach laminations with backwash structures grade into 4 5 m thick bar trough sequences then the extensive nearshore facies as wave energy increases from low h b h b 2 5 m the vertical extent of the beach to nearshore sequence increases from

strong near surface seismic anisotropy of taiwan revealed by coda interferometry abstract we report the near surface v p shear wave velocity v s v p v s ratio poisson s ratio and v s anisotropy of taiwan by applying seismic coda interferometry to 34 borehole surface station pairs we find clear characteristic cos 2 dependence of v s in all the determinations and about half of the amplitudes of anisotropy are larger than 10 with the largest amplitudes up to 34 the patterns of anisotropy fall into two categories opa orogeny parallel anisotropy and saa stress aligned anisotropy both types of anisotropy fit well the local geological fabrics and or the ambient stress and show strong correlation with the poisson s ratios at the borehole sites with these new findings and reported tomographic results we infer that the saa are likely confined to the uppermost portion of the crust in particular to the fluid saturated late quaternary deposits the strong near surface anisotropy also implies that delay times contributed by the shallow crust might have been underestimated in studies of shear wave splitting measurements using the direct arrivals of earthquake waves

autocorrelation analysis of ambient noise in northeastern japan subduction zone abstract we obtained ambient seismic noise interferograms as seismic reflection images using autocorrelation functions acfs in the northeastern japan subduction zone the acfs with a time window length of 120 s were calculated from the continuous seismic records obtained at each seismic station over an analysis period of 300 days these acfs show some distinct signals with relatively large amplitude without any significant temporal variations during the analysis period the signals which are stable appear at both small lag times of less than 10 s and large lag times of 20 50 s during the analysis period the lag time of 10 s corresponds to the travel time of the pp reflection arrival from the continental mohorovicic discontinuity the signals with the large lag times between 30 and 50 s correspond to the back scattered signals from the mantle wedge or the plate boundary these signals are identified clearly at the stations located on the back arc side in the acfs calculated from the records obtained from the fore arc side stations weak signals interpreted as the reflection from the plate boundary with a lag time range of 20 to 30 s are observed we constructed depth migrated images using the acfs to obtain the reflectivity profile by assuming that the acfs represent green s functions composed of a random wavefield excited by stochastic sources or scatterers distributed in the vertical or near vertical direction from the stations further we assumed that the acfs can be treated as zero offset seismic traces recorded at each of the stations the depth migrated images show a relatively seismically transparent structure within the subducting pacific slab and a reflective structure within the mantle wedge this reflective structure is characterized by low velocity zones corresponding to the wedge flow imaged by 3 d seismic velocity tomography

p and s velocity structure in the groningen gas reservoir from noise interferometry noise interferometry has proven to be a powerful tool to image seismic structure in this study we used data from 10 geophones located in a borehole at 3 km depth within the groningen gas reservoir in the netherlands the continuous data cross correlations show that noise predominantly comes in from above the observed daily and weekly variations further indicate that the noise has an anthropogenic origin the direct p wave emerges from the stacked vertical component cross correlations with frequencies up to 80 hz and the direct s wave is retrieved from the horizontal components with frequencies up to 50 hz the measured inter geophone travel times were used to retrieve the p and s velocity structure along the borehole and a good agreement was found with well log data in addition from the s wave polarizations we determined azimuthal anisotropy with a fast direction of n65 w 18 and an estimated magnitude of 4 2 the fast polarization direction corresponds to the present direction of maximum horizontal stress measured at nearby boreholes but is also similar to the estimated paleostress direction

tectonics of the qinling central china tectonostratigraphy geochronology and deformation history abstract the qinling orogen preserves a record of late mid proterozoic to cenozoic tectonism in central china high pressure metamorphism and ophiolite emplacement songshugou ophiolite assembled the yangtze craton including the lower qinling unit into rodinia during the 1 0 ga grenvillian orogeny the lower qinling unit then rifted from the yangtze craton at 0 7 ga subsequent intra oceanic arc formation at 470 490 ma was followed by accretion of the lower qinling unit first to the intra oceanic arc and then to the sino korea craton subduction then imprinted a 400 ma andean type magmatic arc onto all units north of the northern liuling unit oblique subduction created silurian devonian wnw trending sinistral transpressive wrench zones e g lo nan shang dan and late permian early triassic subduction reactivated them in dextral transpression lo nan shang xiang shang dan and subducted the northern edge of the yangtze craton exhumation of the cratonal edge formed the wudang metamorphic core complex during dominantly pure shear crustal extension at 230 235 ma post collisional south directed shortening continued through the early jurassic cretaceous reactivation of the qinling orogen started with nw se sinistral transtension coeval with large scale early cretaceous crustal extension and sinistral transtension in the northern dabie shan it presumably resulted from the combined effects of the siberia mongolia sino korean and lhasa west burma qiangtang indochina collisions and pacific subduction regional dextral wrenching was active within a ne sw extensional regime between 60 and 100 ma an early cretaceous andean type continental magmatic arc with widespread early cretaceous magmatism and back arc extension was overprinted by shortening related to the collision of yangtze indochina block with the west philippines block strike slip and normal faults associated with eocene half graben basins record paleogene nne ssw contraction and wnw ese extension the neogene is characterized by normal faults and nne trending sub horizontal extension pleistocene quaternary nw se extension and ne sw contraction comprises sinistral strike slip faults and is part of the nw se extension imposed across eastern asia by the india asia collision

estimating near surface shear wave velocities in japan by applying seismic interferometry to kik net data 1 we estimate shear wave velocities in the shallow subsurface throughout japan by applying seismic interferometry to the data recorded with kik net a strong motion network in japan each kik net station has two receivers one receiver on the surface and the other in a borehole by using seismic interferometry we extract the shear wave that propagates between these two receivers applying this method to earthquake recorded data at all kik net stations from 2000 to 2010 and measuring the arrival time of these shear waves we analyze monthly and annual averages of the near surface shear wave velocity all over japan shear wave velocities estimated by seismic interferometry agree well with the velocities obtained from logging data the estimated shear wave velocities of each year are stable for the niigata region we observe a velocity reduction caused by major earthquakes for stations on soft rock the measured shear wave velocity varies with the seasons and we show negative correlation between the shear wave velocities and precipitation we also analyze shear wave splitting by rotating the horizontal components of the surface sensors and borehole sensors and measuring the dependence on the shear wave polarization this allows us to estimate the polarization with the fast shear wave velocity throughout japan for the data recorded at the stations built on hard rock sites the fast shear wave polarization directions correlate with the direction of the plate motion

application of seismic interferometry to extract p and s wave propagation and observation of shear wave splitting from noise data at cold lake alberta canada we extract downward propagating p and s waves from industrial noise generated by human and or machine activity at the surface propagating down a borehole at cold lake alberta canada and measure shear wave splitting from these data the continuous seismic data are recorded at eight sensors along a downhole well during steam injection into a 420 470 m deep oil reservoir we crosscorrelate the waveforms observed at the top sensor and other sensors to extract estimates of the direct p and s wave components of the green s function that account for wave propagation between sensors fast high frequency and slow low frequency signals propagating vertically from the surface to the bottom are found for the vertical and horizontal components of the wave motion which are identified with p and s waves respectively the fastest s wave polarized in the east northeast west southwest direction is about 1 9 faster than the slowest s wave polarized in the northwest southeast direction the direction of polarization

virtual source applications to imaging and reservoir monitoring the virtual source method is a breakthrough that allows us to image and monitor the subsurface in cases where surface seismic or vsp fail to deliver in settings where the overburden is complex or changing traditional time lapse signals are weak or nonrepeatable leading to ineffective seismic input to reservoir modeling and little of value generated by repeated seismic surveys on the other hand the virtual source method allows us to image under complex overburden yields repeatable data for reservoir monitoring enables shear seismic and may help us look ahead as we drill

elastic wavefield interferometry using p wave source vsps at the wamsutter field wyoming in this study elastic wavefield interferometry was used to recover p and s waves from the 3d p wave vibrator vsp data at wamsutter field in wyoming s wave velocity and birefringence is of particular interest for the geophysical objectives of lithology discrimination and fracture characterization in naturally fractured tight gas sand reservoirs because we rely on deconvolution interferometry for retrieving interreceiver p and s waves in the subsurface the output fields are suitable for high resolution local reservoir characterization in 1d media where the borehole is nearly vertical data at the stationary phase point is not conducive to conventional interferometry strong tube wave noise generated by physical sources near the borehole interfere with s wave splitting analyses also converted p to s wave ps wave polarity reversals occur at zero offset and cancel their recovery we developed methods to eliminate tube wave noise by removing physical sources at the stationary phase point and pertur

surface wave tomography from microseisms in southern california received 5 april 2005 revised 23 may 2005 accepted 9 june 2005 published 26 july 2005 1 since it has already been demonstrated that point topoint seismic propagation green functions can be extracted from seismic noise it should be possible to image earth structure using the ambient noise field seismic noise data from 148 broadband seismic stations in southern california were used to extract the surface wave arrival times between all station pairs in the network the seismic data were then used in a simple but densely sampled tomographic procedure to estimate the surface wave velocity structure within the frequency range of 0 1 0 2 hz for a region in southern california the result compares favorably with previous estimates obtained using more conventional and elaborate inversion procedures this demonstrates that coherent noise field between station pairs can be used for seismic imaging purposes citation sabra k g p gerstoft p roux w a kuperman and m c fehler 2005 surface wave tomography from microseisms in southern california geophys res lett 32 l14311 doi 10 1029 2005gl023155

extracting earth s elastic wave response from noise measurements recent research has shown that noise can be turned from a nuisance into a useful seismic source in seismology and other fields in science and engineering the estimation of the system response from noise measurements has proven to be a powerful technique to convey the essence of the method we first treat the simplest case of a homogeneous medium to show how noise measurements can be used to estimate waves that propagate between sensors we provide an overview of physics research dating back more than 100 years showing that random field fluctuations contain information about the system response this principle has found extensive use in surface wave seismology but can also be applied to the estimation of body waves because noise provides continuous illumination of the subsurface the extracted response is ideally suited for time lapse monitoring we present examples of time lapse monitoring as applied to the softening of soil after the 2011 tohoku oki earthquake the detection of a precursor to a landslide and temporal changes in the lunar soil

generalised receiver functions and seismic interferometry abstract classical seismological receiver functions are correlational or deconvolutional combinations of vertical and horizontal component seismometer recordings of earthquake waves that focus information on near receiver subsurface earth structure and properties we show that seismic interferometry can be thought of as a generalisation of receiver functions analysis to cases where recordings at pairs of receivers are considered simultaneously and where either the same or different component recordings are combined further seismic interferometry uses any of deconvolution convolution and cross correlation and energy from either impulsive or random noise sources we show both how receiver functions can logically be extended to a new convolutional form and that the now little used correlational form of receiver functions contains more intuitive information than previously realised seismic interferometry has provided other extraordinary extensions to seismologists arsenal passive noise recordings can be converted into seismograms from virtual imagined earthquakes that in turn can be used to image the real earth active sources e g earthquakes or man made sources can be redatumed into new virtual sources elsewhere or can be converted into virtual sensors seismometers that record seismograms from other real earthquakes man made sources or noise sources that occur either in the future or in the past and the ability to construct virtual sources and sensors at desired times and locations rather than having to wait for earthquake sources that occur at uncontrollable locations promises more repeatable monitoring of changes in earth subsurface properties over time indeed so called coda wave interferometry offers unprecedented accuracy in detecting such changes finally existing theoretical extensions to other regimes such as electromagnetic electrokinetic and diffusive energy propagation may lead to future revolutions in other domains of science

exhumation of ultrahigh pressure rocks beneath the hornelen segment of the nordfjord sogn detachment zone western norway the nordfjord sogn detachment zone of western norway represents an archetype for crustal scale normal faults that are typically cited as one of the primary mechanisms responsible for the exhumation of ultrahighpressure uhp terranes in this paper we investigate the role of normal sense shear zones with respect to uhp exhumation using structural geology thermobarometry and geochronology of the hornelen segment of the nordfjord sogn detachment zone the hornelen segment of the zone is a 2 6 km thick top w shear zone primarily developed within amphibolite grade allochthonous rocks that juxtaposes the uhp rocks of the western gneiss complex in its footwall with lower grade allochthons and carboniferous devonian basins in its hanging wall new thermobarometry and sm nd garnet geochronology show that these top w fabrics were initiated at lower crustal depths of 30 40 km between 410 ma and 400 ma structural geology and quartz petrofabrics indicate that top w shear was initially relatively evenly distributed across the shear zone and then overprinted by discrete ductile brittle detachment faults at slower strain rates during progressive deformation and exhumation these results require a three stage model for uhp exhumation in which normal sense shear zones exhumed uhp rocks from the base of the crust along initially broad ductile shear zones that were progressively overprinted by discrete ductile brittle structures

the influence of geomorphology and sedimentary processes on benthic habitat distribution and littoral sediment dynamics geraldton western australia abstract understanding of the processes regulating sediment transport accumulation and erosion requires an appropriate mapping of coastal geomorphology seabed sediments and benthic habitat distribution to allow management issues to be identified understood and addressed in this study multibeam echo sounder data were used to map shallow water geomorphological features and the spatial distribution of benthic habitats with the support of underwater imagery for ground truthing the acoustic data at geraldton sediment analyses have revealed a dominant biogenic nature with modern carbonate sedimentation linked to the seagrass and macroalgal carbonate factories colonising these shallow

interferometric assessment of clamping quality of borehole geophones borehole arrays are often preferred over surface installations for hydraulic fracture monitoring of deep experiments due to their proximity to the treatment zone borehole geophone strings are typically clamped to the observation wellbore wall using electromechanical or magnetic devices in order for them to be in close contact with the surrounding formations and record the background noise and propagating wavefields related to the microseismic experiments this contact needs to be maintained throughout the recording time we have used seismic interferometry to assess the clamping quality of borehole geophone arrays we determined that the characteristics of the retrieved crosscorrelation functions between a reference receiver and other receivers in an array are indicative of the clamping quality of the former geophone to the borehole wall we have also defined the concept of separation frequency or emergence frequency as the frequency below which direct body waves propagating along the receiver line are clearly observed on the crosscorrelation gathers the crosscorrelation gathers associated with poorly clamped geophones show predominantly tube waves or incoherent waveforms body waves only emerge below very low separation frequencies the crosscorrelation gathers of relatively better coupled geophones on the other hand have higher separation frequencies we have applied this method to four different borehole microseismic data sets labeled here as a b c and d of which data set d was previously known to suffer from some clamping issues data sets b and c with inferred better coupling had separation frequencies of approximately 60 hz whereas the other two data sets are characterized by lower separation frequencies 15 hz for data set a and 20 hz for data set d suggesting relatively poorer coupling

time lapse change in anisotropy in japan s near surface after the 2011 tohoku oki earthquake 1 we apply seismic interferometry to strong motion records to detect the near surface i e an upper few hundred meters deep change in anisotropy caused by the mw9 0 tohoku oki earthquake on 11 march 2011 we show that the earthquake increased the difference between fast and slow shear wave velocities arising from shear wave splitting in most parts of northeastern japan but it did not significantly change fast shear wave polarization directions in the near surface through monitoring of anisotropy and shear wave velocity we find that the changes in anisotropy and velocity partially recover with time they are however still different from the pre event values after nine months the comparison of the spatial distribution between changes in anisotropy and velocity indicates the changes in anisotropy and velocity are generally correlated especially in the northeastern honshu the main island in japan the change in the largest principal stress direction weakly correlates with the change in anisotropy

the fate of subducted continental margins two stage exhumation of the high pressure to ultrahigh pressure western gneiss region norway thermobarometry suggests that ultrahigh pressure uhp to high pressure hp rocks across the western gneiss region ponded at the moho following as much as 100 km of exhumation through the mantle and before exhumation to the upper crust eclogite across the c 22 000 km 2 study area records minimum pressures of c 8 18 kbar and temperatures of c 650 780 c one orthopyroxene eclogite yields an uhp of c 28 5 kbar and evidence of former coesite has been found c 50 km farther east than previously known despite this widespread evidence of uhp to hp thermobarometry of metapelite and garnet amphibolite samples reveals a surprisingly uniform supra barrovian amphibolite facies overprint at c 11 kbar and c 650 750 c across the entire area chemical zoning analysis suggests that garnet in these samples grew during heating and decompression presumably during the amphibolite facies event these data indicate that the norwegian uhp hp province was exhumed from mantle depths of c 150 km to lower crustal depths where it stalled and underwent a profound high temperature overprint the ubiquity of late stage supra barrovian metamorphic overprints suggests that large scale collisional uhp terranes routinely stall at the continental moho where diminishing body forces are exceeded by boundary forces significant portions of the middle or lower crust worldwide may be formed from uhp terranes that were arrested at the moho and never underwent their final stage of exhumation

analysis of microearthquake data at cold lake and its applications to reservoir monitoring more than four months of continuously recorded micro earthquake data acquired at cold lake canada was analyzed using advanced algorithms for microearthquake location and subsurface tomography robust determination of the spatial temporal and magnitude distribution of seismicity is the first step toward understanding the relationship between the stress perturbations caused by the cyclic steam stimulation css process and seismicity acquisition geometry was constrained because the receivers were located in a single vertical borehole despite this constraint we were successful in improving event locations by use of the double difference method which highlights several tight event clusters the deep cluster at a depth of 400 m just above the oil reservoir shows very high seismicity during the css processes a second cluster is observed at shallower depths in the successive steam cycle this suggests that repeated steaming causes the deformation to spread to shallower depths the number of events h

temporal change in shear velocity and polarization anisotropy related to the 2011 m9 0 tohoku oki earthquake examined using kik net vertical array data 1 the m9 0 tohoku oki earthquake took place off ne japan which is covered by a dense seismic network in particular kik net observed the strong motions of the main shock and numerous aftershocks both on the ground and at the bottom of boreholes at a depth of a few hundred meters we applied cross correlation analysis to the coda part of a seismogram observed by kik net and estimated not only the temporal change in shear velocity but also the change in polarization anisotropy between the bottom of the borehole and the ground the shear velocity was suddenly reduced by 5 to 10 after the tohoku oki earthquake over a wide area of ne japan which is consistent with the results of a previous study although some stations also reveal a change in polarization anisotropy the polarization anisotropy change is smaller than the velocity change which may suggest that the static stress change due to the coseismic slip on the pacific plate is not large enough to change the direction of polarization anisotropy and or deviatoric stress in the land area of ne japan

seismic interferometry of teleseicmic s wave coda for retrieval of body waves an application to the philippine sea slab underneath the japanese islands summary the reconstruction of surface waves from the cross correlation of random wavefields has recently been extensively inspected by theoretical and experimental approaches however the reconstruction of body waves has not been extensively studied in this study we present a method for extracting body waves that is direct p and s waves and reflected waves from the philippine sea slab we use the cross correlation of the wavefield generated by the teleseismic s waves observed by hi net tiltmeters with a passband of 0 07 0 5 hz to enhance the contribution of the s coda we reduced the source time function and the deterministic phases ss scs and ss and the surface wave in s coda the records of the processed s coda observed at every station pair are cross correlated for each teleseismic event the cross correlation functions ccfs of different earthquakes are stacked to retrieve wavefields propagating between the station pairs as a result direct p s and the reflected waves could be extracted when the stacked ccfs are aligned as a function of distance of separation between two stations the gradients of the traveltime curves for the direct p and s waves are approximately 5 7 and 3k m s 1 respectively these velocities correspond to the seismic velocities of the crust or the p wave velocity of the uppermost mantle in order to enhance the reflected waves we searched for the reflection points by assuming that the later phases in the ccfs are ss reflections and map the amplitudes onto the depth sections as a result the negative phases dipping to the north can be traced right below the region of hypocentre distribution these negative phases probably correspond to the oceanic moho within the philippine sea slab we also show that the oceanic moho can also be traced by assuming pp reflections these results indicate that the ccfs plausibly contain information regarding both p and s waves propagating between the two receivers and are capable of detecting reflected phases in addition to the direct waves

shear wave anisotropy from cross correlation of seismic noise in the parkfield pilot hole summary we use cross correlation of seismic noise recorded at stations in the san andreas fault observatory at depth safod pilot hole to extract p and s waves and measure s wave anisotropy on the horizontal components the data are recorded at seven three component stations at depths from 1857 to 2097 m in the pilot hole in late september and early 2004 october drilling noise underneath the stations generated propagating waves which were absent in the rest of october estimates of the p and s wave velocities from the cross correlations on the vertical and horizontal components respectively are consistent with velocity measurements taken directly in the borehole we observe polarization of the s wave with a fast polarization direction of 120 130 that is 4 per cent faster than the slow direction cross correlation of the seismic noise can accurately determine s wave anisotropy

ambient noise rayleigh wave tomography of new zealand summary we present the first new zealand wide study of surface wave dispersion using ambient noise observed at 42 broad band stations in the national seismic network geonet and the global seismic network gsn year long vertical component time series recorded between 2005 april 1 and 2006 march 31 have been correlated with one another to yield estimated fundamental mode rayleigh wave green s functions we filter these green s functions to compute rayleigh wave group dispersion curves at periods of 5 50 s using a phase matched filter frequency time analysis technique the uncertainties of the measurements are estimated based on the temporal variation of the dispersion curves revealed by 12 overlapping 3 month stacks after selecting the highest quality dispersion curve measurements we compute group velocity maps from 7 to 25 s period these maps and 1 d shear wave velocity models at four selected locations exhibit clear correlations with major geological structures including the taranaki and canterbury basins the hikurangi accretionary prism and previously reported basement terrane boundaries