partitioning of kinetic energy in the arctic ocean s beaufort gyre kinetic energy ke in the arctic ocean s beaufort gyre is dominated by the mesoscale eddy field that plays a central role in the transport of freshwater heat and biogeochemical tracers understanding beaufort gyre ke variability sheds light on how this freshwater reservoir responds to wind forcing and sea ice and ocean changes the evolution and fate of mesoscale eddies relate to energy pathways in the ocean e g the exchange of energy between barotropic and baroclinic modes mooring measurements of horizontal velocities in the beaufort gyre are analyzed to partition ke into barotropic and baroclinic modes and explore their evolution we find that a significant fraction of water column ke is in the barotropic and the first two baroclinic modes we explain this energy partitioning by quantifying the energy transfer coefficients between the vertical modes using the quasi geostrophic potential vorticity conservation equations with a specific background stratification observed in the beaufort gyre we find that the quasi geostrophic vertical mode interactions uphold the persistence of ke in the first two baroclinic modes consistent with observations our results explain the specific role of halocline structure on ke evolution in the gyre and suggest depressed transfer to the barotropic mode this limits the capacity for frictional dissipation at the sea floor and suggests that energy dissipation via sea ice ocean drag may be prominent

prediction of coal seam details and mining safety using multicomponent seismic data a case history from china abstractwith the increasing mining depth of coal mines geologic hazards have become the main source of accidents for this reason coal seam prediction requires more assessment parameters such as the degree of anisotropy vp vs value and elastic modulus these parameters are difficult to determine using only the pp wave we have inverted and interpreted multicomponent seismic data acquired from a 2 56 km2 area in the guqiao mine located on the southern margin of the north china plate under the constraints of drill log and rock physics test data the production coal seam 11 2 of the mine located in the permian formation was our focus of this study and our objective was to determine the structure fracture development thickness surrounding rock lithology roof stability and mining safety of the seam to achieve this we first performed an analysis of s wave splitting and joint pp and ps wave inversions the inversion results were then combined to derive additional parameters such as the vp vs

basinwide integrated volume transports in an eddy filled ocean the temporal evolution of the strength of the atlantic meridional overturning circulation amoc in the subtropical north atlantic is affected by both remotely forced basin scale meridionally coherent climate relevant transport anomalies such as changes in high latitude deep water formation rates and locally forced transport anomalies such as eddies or rossby waves possibly associated with small meridional coherence scales which can be considered as noise the focus of this paper is on the extent to which local eddies and rossby waves when impinging on the western boundary of the atlantic affect the temporal variability of the amoc at 26 5 degrees n continuous estimates of the amoc at this latitude have been made since april 2004 by combining the florida current ekman and midocean transports with the latter obtained from continuous density measurements between the coasts of the bahamas and morocco representing respectively the western and eastern boundaries of the atlantic at this latitude within 100 km of the western boundary there is a threefold decrease in sea surface height variability toward the boundary observed in both dynamic heights from in situ density measurements and altimetric heights as a consequence the basinwide zonally integrated upper midocean transport shallower than 1000 m as observed continuously between april 2004 and october 2006 varies by only 3 0 sv 1 sv 10 6 m 3 s 1 rms instead upper midocean transports integrated from western boundary stations 16 40 and 500 km offshore to the eastern boundary vary by 3 6 6 0 and 10 7 sv rms respectively the reduction in eddy energy toward the western boundary is reproduced in a nonlinear reduced gravity model suggesting that boundary trapped waves may account for the observed decline in variability in the coastal zone because they provide a mechanism for the fast equatorward export of transport anomalies associated with eddies impinging on the western boundary an analytical model of linear rossby waves suggests a simple scaling for the reduction in thermocline thickness variability toward the boundary physically the reduction in amplitude is understood as along boundary pressure gradients accelerating the fluid and rapidly propagating pressure anomalies along the boundary the results suggest that the local eddy field does not dominate upper midocean transport or amoc variability at 26 5 degrees n on interannual to decadal time scales

the vertical partition of oceanic horizontal kinetic energy to produce an interpretation of the surface kinetic energy as measured by altimeters a survey is made of the vertical structure of kinetic energy profiles in a large number of globally distributed long current meter records although the data are geographically confined primarily to a latitude band in the north pacific to the north atlantic and to a few moorings in the south atlantic the results show generally speaking that most regions are dominated by the barotropic and first baroclinic modes because of the near surface intensification of baroclinic modes altimeters primarily reflect the first baroclinic mode and thus the motion of the main thermocline there is good quantitative agreement with a few exceptions with estimates of the surface kinetic energy obtained from the topex poseidon altimeter and from vertical extrapolations to the surface of the mooring profiles these results are consistent with previous suggestions that barotropic models have little skill in depicting variability as seen in the altimeter data an eof analysis is shown to produce fictitious mode coupling unless the dynamical modes have very different energy levels

moored observations of western boundary current variability and thermohaline circulation at 26 5 n in the subtropical north atlantic abstract a 5 8 year time series of moored current meter observations is used with hydrographic section data cme model results and gridded wind fields over the north atlantic to describe the mean structure and variability of circulation and volume transports east of abaco bahamas at 26 5 n a mean antilles current with 5 sv of northward transport is confined against the bahamas boundary in the upper 800 m and combines with approximately 19 sv of florida current transport to balance the sverdrup interior circulation and does not contribute to interhemispheric exchange the mean transport of the deep western boundary current dwbc off the bahamas is approximately 40 sv of which 13 sv compensates the upper branch of the thermohaline circulation requiring a 27 sv deep recirculation robust annual and semiannual cycles of meridional are found in both moored observations and model results with remarkable agreement in amplitude 13 sv and phase maximum northward transports occur in winter and summer

mass and volume transport variability in an eddy filled ocean eddy activity in the north atlantic ocean produces fluctuations in ocean wide volume transport on the order of 20 106 cubic metres per second on multi year timescales such background noise makes it impossible to detect possible trends in the ocean circulation due to a changing climate without multi decadal observations in three spatial dimensions the possibility that the oceanic general circulation is undergoing changes as part or the cause of major climate shifts is being intensely discussed1 with some published results relying on data from moorings spanning the north atlantic ocean2 3 the circulation is however extremely noisy here i use existing estimates of the frequency and wavenumber content of geostrophic eddies in the ocean4 to show that variations in ocean wide integrated transport must appear even in the absence of a true long term trend expected fluctuations exceed 20 109 kg s 1 or 20 106 m3 s 1 and exhibit multi year timescales existing knowledge of the eddy field allows predictions of observed variability and produces lower bounds on the multi decadal timescale required to detect true trends of a large magnitude detecting and understanding the effect of climate change on the ocean circulation requires observations in three dimensions over long periods of time

pathways of eddies in the south atlantic ocean revealed from satellite altimeter observations 1 the majority of the kinetic energy of ocean currents is contained in the mesoscale eddies the pathways of ocean eddies which are the weather of ocean circulation are mapped from space using a decade long record of sea surface height measured by two simultaneously flying satellite radar altimeters the speed and direction of the propagation of eddies in the south atlantic ocean are presented in the paper the patterns of the eddy propagation velocity reveal the effects of the interaction between mean flow and eddies with strong influence of bottom topography the information describes a unique property of the ocean general circulation and serves as a basis for testing ocean models

observations inferences and mechanisms of the atlantic meridional overturning circulation a review this is a review about the atlantic meridional overturning circulation amoc its mean structure temporal variability controlling mechanisms and role in the coupled climate system the amoc plays a central role in climate through its heat and freshwater transports northward ocean heat transport achieved by the amoc is responsible for the relative warmth of the northern hemisphere compared to the southern hemisphere and is thought to play a role in setting the mean position of the intertropical convergence zone north of the equator the amoc is a key means by which heat anomalies are sequestered into the ocean s interior and thus modulates the trajectory of climate change fluctuations in the amoc have been linked to low frequency variability of atlantic sea surface temperatures with a host of implications for climate variability over surrounding landmasses on intra annual timescales variability in amoc is large and primarily reflects the response to local wind forcing meridional coherence of anomalies is limited to that of the wind field on interannual to decadal timescales amoc changes are primarily geostrophic and related to buoyancy anomalies on the western boundary a pacemaker region for decadal amoc changes is located in a western transition zone along the boundary between the subtropical and subpolar gyres decadal amoc anomalies are communicated meridionally from this region amoc observations as well as the expanded ocean observational network provided by the argo array and satellite altimetry are inspiring efforts to develop decadal predictability systems using coupled atmosphere ocean models initialized by ocean data

high resolution seismic reflection imaging of a thin diamondiferous kimberlite dyke seismic reflection techniques are for the first time used to image a thin diamondiferous kimberlite dyke from subcrop to depths greater than 1300 m geophysical exploration for kimberlite deposits typically involves airborne potential field surveys that are well suited for detecting vertical outcropping pipes but often fail to reveal thin subhorizontal dykes and sills because seismic techniques are especially well suited for mapping structures that have shallow dips and strong impedance contrasts a feasibility study and seismic reflection survey were undertaken on the diamondiferous snap lake dyke northwest territories canada to evaluate the potential for using seismic techniques on these targets the dyke average thickness 2 3 m provides an excellent test site because a drilling program has defined the gross dyke geometry and provides core samples from the kimberlite and host rocks the feasibility study involved measuring p velocity and density of selected cores using these data reflectivit

variability of shallow and deep western boundary currents off the bahamas during 2004 05 results from the 26 n rapid moc array data from an array of six moorings deployed east of abaco bahamas along 26 5 n during march 2004 may 2005 are analyzed these moorings formed the western boundary array of a transbasin observing system designed to continuously monitor the meridional overturning circulation and meridional heat flux in the subtropical north atlantic under the framework of the joint u k u s rapid climate change rapid meridional overturning circulation moc program important features of the western boundary circulation include the southward flowing deep western boundary current dwbc below 1000 m and the northward flowing antilles current in the upper 1000 m transports in the western boundary layer are estimated from direct current meter observations and from dynamic height moorings that measure the spatially integrated geostrophic flow between moorings the results of these methods are combined to estimate the time varying transports in the upper and deep ocean over the width of the western boundary layer to a distance of 500 km offshore of the bahamas escarpment the net southward transport of the dwbc across this region inclusive of northward deep recirculation is 26 5 sv sv 10 6 m 3 s 1 which is divided nearly equally between upper 13 9 sv and lower 12 6 sv north atlantic deep water nadw in the top 1000 m 6 0 sv flows northward in a thermocline intensified jet near the western boundary these transports are found to agree well with historical current meter data in the region collected between 1986 and 1997 variability in both shallow and deep components of the circulation is large with transports above 1000 m varying between 15 and 25 sv and deep transports varying between 60 and 3 sv much of this transport variability associated with barotropic fluctuations occurs on relatively short time scales of several days to a few weeks upon removal of the barotropic fluctuations slower baroclinic transport variations are revealed including a temporary stoppage of the lower nadw transport in the dwbc during november 2004

generation of internal waves by eddies impinging on the western boundary of the north atlantic abstractdespite the major role played by mesoscale eddies in redistributing the energy of the large scale circulation our understanding of their dissipation is still incomplete this study investigates the generation of internal waves by decaying eddies in the north atlantic western boundary the eddy presence and decay are measured from the altimetric surface relative vorticity associated with an array of full depth current meters extending 100 km offshore at 26 5 n in addition internal waves are analyzed over a topographic rise from 2 yr high frequency measurements of an acoustic doppler current profiler adcp which is located 13 km offshore in 600 m deep water despite an apparent polarity independence of the eddy decay observed from altimetric data the flow in the deepest 100 m is enhanced for anticyclones 25 2 cm s 1 compared with cyclones 4 7 cm s 1 accordingly the internal wave field is sensitive to this polarity dependent deep velocity this is apparent from the eddy modulated enhanc

application of a high resolution seismic investigation in a greek coal mine high resolution seismic methods were applied to map the detailed structure and thickness of the domeniko coal basin central greece and to search for lateral discontinuities such as pinch outs and faults extensive tests were performed to optimize recording parameters and equipment reflection events which can be attributed to coal layers can be interpreted from depths of approximately 30 to 150 m on cdp stacked and inverted sections several low throw faults have been interpreted from the sections results obtained from the high resolution seismic reflection survey combined with drillhole information clearly revealed the 3 d model of the coal field using geostatistical methods the results of the high resolution reflection seismic survey were combined with the information from the borehole program to clearly reveal the 3 d model of the basin

variability of the deep western boundary current at 26 5 n during 2004 2009 five years of data from a line of dynamic height moorings dhm bottom pressure recorders bpr and pressure equipped inverted echo sounders pies near the atlantic ocean western boundary at 26 51n are used to evaluate the structure and variability of the deep western boundary current dwbc during 2004 2009 comparisons made between transports estimated from the dhm bpr and those made by the pies demonstrate that the two systems are collecting equivalent volume transport information correlation coefficient r 0 96 root mean square difference 6 sv 1 sv 10 6 m 3 s 1 integrated to 450 km off from the continental shelf and between 800 and 4800 dbar the dwbc has a mean transport of approximately 32 sv and a standard deviation during these five years of 16 sv both the barotropic full depth vertical mean and baroclinic flows have significant variability changes exceeding 10 sv on time scales ranging from a few days to months with the barotropic variations being larger and more energetic at all time scales the annual cycle of the deep transport is highly dependent on the horizontal integration distance integrating 100 km offshore yields an annual cycle of roughly similar magnitude but shifted in phase relative to that found from current meter arrays in the 1980 1990s while the annual cycle becomes quite weak when integrating 450 km offshore variations in the dwbc transport far exceed those of the total basin wide meridional overturning circulation standard deviations of 16 sv vs 5 sv transport integrated in the deep layer out to the west side of the mid atlantic ridge still demonstrates a surprisingly high variance indicating that some compensation of the western basin deep variability must occur in the eastern basin published by elsevier ltd

geographical variability of the first baroclinic rossby radius of deformation global 1 83 18 climatologies of the first baroclinic gravity wave phase speed c1 and the rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles these new atlases are compared with previously published 5 83 58 coarse resolution maps of l1 for the northern hemisphere and the south atlantic and with a 1 83 18 fine resolution map of c1 for the tropical pacific it is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5 15 owing to seemingly minor computational errors geographical variations in the new high resolution maps of c1 and l1 are discussed in terms of a wkb approximation that elucidates the effects of earth rotation stratification and water depth on these quantities it is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and l1 at any particular location in the world ocean this is rationalized from consideration of the wkb approximation

on the propagation and decay of north brazil current rings near the western boundary of the tropical north atlantic where the north brazil current nbc retroflects into the north equatorial countercurrent large anticyclonic rings are shed after separating from the retroflection region the so called nbc rings travel northwestward along the brazilian coast until they reach the island chain of the lesser antilles and disintegrate these rings contribute substantially to the upper limb return flow of the atlantic meridional overturning circulation by carrying south atlantic water into the northern subtropical gyre their relevance for the northward transport of south atlantic water depends on the frequency of their generation as well as on their horizontal and vertical structure the ring shedding and propagation and the complex interaction of the rings with the lesser antilles are investigated in the inline equation family of linked atlantic model experiments flame model the ring properties simulated in flame reach the upper limit of the observed rings in diameter and agree with recent observations on seasonal variability which indicates a maximum shedding during the first half of the year when the rings reach the shallow topography of the lesser antilles they are trapped by the island triangle of st lucia barbados and tobago and interact with the island chain the model provides a resolution that is capable of resolving the complex topographic conditions at the islands and illuminates various possible fates for the water contained in the rings it also reproduces laboratory experiments that indicate that both cyclones and anticyclones are formed after a ring passes through a topographic gap trajectories of artificial floats which were inserted into the modeled velocity field are used to investigate the pathways of the ring cores and their fate after they encounter the lesser antilles the majority of the floats entered the caribbean while the northward atlantic pathway was found to be of minor importance no prominent pathway was found east of barbados where a ring could avoid the interaction with the islands and migrate toward the northern lesser antilles undisturbed

seismic facies analysis of delta plain coals from camrose alberta and lacustrine coals from pictou coalfield nova scotia facies models of two coalfields in canada have been developed through seismic facies analysis fluvial deltaic upper cretaceous coals near camrose alberta are characterized by hummocky subparallel high amplitude reflections that are laterally continuous over distances of several kilometers deposition in an extensive delta plain swamp is inferred coals of pennsylvanian age in the pictou coalfield nova scotia occur in two distinct seismic facies parallel to subparallel relatively continuous reflections are interpreted to define a basinal facies comprising thick coals and lacustrine sediments basinal margin facies contain a greater abundance of variable clastic sediments and are recognized by discontinuous subparallel to chaotic reflections further improvements n stratigraphic analysis will require synthetic seismograms to analyze individual reflections in terms of the thickness and separation of seams and to enable interseam multiples to be recognized

vertical structure of eddies and rossby waves and their effect on the atlantic meridional overturning circulation at 26 5 n the meridional overturning circulation moc at inline image in the atlantic has a standard deviation of 4 9 sv and contains large fluctuations at subannual periods the geostrophic component of the moc is believed to be influenced on subannual time scales by eddies and rossby waves to quantify this effect the vertical structure and surface characteristics of westward propagating signals are studied using altimetric data and full depth mooring measurements from the rapid array at inline image westward propagating features are observed in the western north atlantic in both data sets and have periods of 80 250 days in the first baroclinic mode these features are still observed by the rapid moorings 20 km offshore of the western boundary the western boundary also exhibits deep variability characterized by enhanced energy in higher baroclinic modes the effect of eddies and rossby waves on the geostrophic transport is quantified by representing their vertical structure with the first baroclinic mode in total 42 of the variance of the transbasin thermocline transport inferred from geostrophic calculations at inline image can be attributed to first mode variability which is associated with eddies and rossby waves at periods of 80 250 days the standard deviation of the transbasin thermocline transport due to eddies and rossby waves is estimated to be 2 6 sv

turbulent mixing in a deep fracture zone on the mid atlantic ridge abstractmidocean ridge fracture zones channel bottom waters in the eastern brazil basin in regions of intensified deep mixing the mechanisms responsible for the deep turbulent mixing inside the numerous midocean fracture zones whether affected by the local or the nonlocal canyon topography are still subject to debate to discriminate those mechanisms and to discern the canyon mean flow two moorings sampled a deep canyon over and away from a sill contraction a 2 layer exchange flow accelerated at the sill transports 0 04 0 10 sv 1 sv 106 m3 s 1 up canyon in the deep layer at the sill the dissipation rate of turbulent kinetic energy e increases as measured from microstructure profilers and as inferred from a parameterization of vertical kinetic energy cross sill density and microstructure transects reveal an overflow potentially hydraulically controlled and modulated by fortnightly tides during spring to neap tides e varies from o 10 9 to o 10 10 w kg 1 below 3500 m around the 2 layer inte

a numerical model study of the effects of interannual time scale wave propagation on the predictability of the atlantic meridional overturning circulation we investigate processes leading to uncertainty in forecasts of the atlantic meridional overturning circulation amoc a climate model is used to supply initial conditions for ensemble simulations in which members initially have identical ocean states but perturbed atmosphere states baroclinic transports diverge on interannual timescales even though the ocean is not eddy permitting interannual fluctuations of the model amoc in the subtropical gyre are caused by westward propagating rossby waves divergence of the predicted amoc with time occurs because the waves develop different phases in different ensemble members predominantly due to differences in eastern boundary windstress curl these windstress fluctuations communicate with interior ocean transports via modifications to the vertical velocity and the vortex stretching term dw dz consequently errors propagate westwards resulting in longer predictability times in the interior ocean compared with the eastern boundary another source of divergence is transport anomalies propagating along the gulf stream and other boundary currents the propagation mechanism seems to be predominantly advection by mean currents and we show that the arrival of westward propagating waves can trigger development of these anomalies the mean state of the amoc has a small effect on interannual predictability in the subtropical gyre most likely because eastern boundary windstress curl predictability is not strongly dependent on the state of the amoc in the subtropics eastern boundary windstress curl was more predictable at 45 degree sign n when the amoc was in a strongly decreasing state but unlike at 30 degree sign n no mechanism was found linking windstress curl fluctuations with deep transports

the scales and equilibration of midocean eddies freely evolving flow quasigeostrophic turbulence theory and numerical simulation are used to study the mechanisms determining the scale structure and equilibration of mesoscale ocean eddies the present work concentrates on using freely decaying geostrophic turbulence to understand and explain the vertical and horizontal flow of energy through a stratified horizontally homogeneous geostrophic fluid it is found that the stratification profile in particular the presence of a pycnocline has significant qualitative effects on the efficiency and spectral pathways of energy flow specifically with uniform stratification energy in high baroclinic modes transfers directly quickly within a few eddy turnaround times and almost completely to the barotropic mode by contrast in the presence of oceanlike stratification kinetic energy in high baroclinic modes transfers intermediately to the first baroclinic mode whence it transfers inefficiently and incompletely to the barotropic mode the efficiency of transfer to the barotropic mode is reduced as the pycnocline is made increasingly thin the b effect on the other hand improves the efficiency of barotropization but for oceanically realistic parameters this effect is relatively unimportant compared to the effects of nonuniform stratification finally the nature of turbulent cascade dynamics is such as to lead to a concentration of first baroclinic mode kinetic energy near the first radius of deformation which in the case of a nonuniform and oceanically realistic stratification has a significant projection at the surface this may in part explain recent observations of surface eddy scales by topex poseidon satellite altimetry which indicate a correlation of surface height variance with the scale of the first deformation radius

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

loop current variability as trigger of coherent gulf stream transport anomalies abstractsatellite observations and output from a high resolution ocean model are used to investigate how the loop current in the gulf of mexico affects the gulf stream transport through the florida

an in hole shotgun source for engineering seismic surveys we have conducted several source comparisons involving 12 gauge and 8 gauge buffalo guns a 7 3 kg sledgehammer and a 75 kg weight drop the results are strongly site dependent we found that when the near surface consisted of fine grained water saturated sediments the 12 gauge buffalo gun produced up to two orders of magnitude more energy than the conventional hammer across a broad frequency range under such conditions the gun produced the greatest improvement in energy between 200 and 400 hz where it yielded up to ten times more energy than the 75 kg weight drop this indicates that the buffalo gun may be particularly useful as a shallow reflection seismic source however at sites where the near surface materials were coarse grained and the water table was well below the ground surface the advantages of using an in hole shotgun source as opposed to a hammer or weight drop were minimal nevertheless in many areas we believe that the buffalo gun is an excellent source for engineering seismic surv

subannual seasonal and interannual variability of the north atlantic meridional overturning circulation abstract an eddy permitting numerical ocean model is used to investigate the variability of the meridional overturning circulation moc both wind stress and fluctuations of the seawater density contribute to moc changes on subannual and seasonal time scales whereas the interannual variability mainly reflects changes in the density field even on subannual and seasonal time scales a significant fraction of the total moc variability is due to changes of the density field in the upper 1000 m of the ocean these changes reflect perturbations of the isopycnal structure that travel westward as rossby waves because of a temporally changing phase difference between the eastern and western boundaries the rossby waves affect the moc by modifying the basinwide east west density gradient both the numerical model used in this study and calculations based on rossby wave theory suggest that this effect can account for an moc variability of several sverdrups sv 106 m3 s 1 these results have implications for t

premine study of shallow coal seams using high resolution seismic reflection methods geological investigations in the illinois basin coalfields have shown that significant differences in safe and economical exploitation of coal depends directly on accurate mapping of the roof rock overlying the seam as well as on geological structures in the coal measures in roof rock transition zones above the herrin no 6 coal where the nonmarine energy shale changes to the anna shale a change often occurs from low to high sulfur coal and from low to high stability roof rocks in many instances use of borehole data alone is inadequate to locate these features in advance of mining high resolution seismic reflection data collected near harco illinois were used as part of premine planning to help predict roof instability areas of low sulfur coal and geologic disturbances several faults channels and facies changes affecting the herrin no 6 and the springfield no 5 coal seams at depths of 137 m and 167 m respectively were interpreted and modeled one and two dimensional synthetic seismo

high resolution 3 d seismic survey over a coal mine reserve area in the u s a case study a high resolution three dimensional 3 d seismic survey was conducted in advance of coal mine development in the illinois basin in may 1989 to better define a geologic structure with the potential to adversely affect longwall mining conditions the 3 d seismic data indicate that an abrupt change in seam elevation or roll encountered near the northern property line trends south into the reserve area and then turns southeast a personal computer based workstation was used to integrate borehole and seismic data for modeling in which 3 d block diagrams of the calculated seam elevations were generated the block diagrams show a steep slope on the west flank of the roll that gradually decreases as the roll turns to the southeast the survey also reveals a geologic structure beneath the roll at an estimated depth of 46 62 m horizontal time slice sections of this feature suggest the presence of a paleochannel that meanders on a similar course as the roll which apparently was connected to a larger paleochannel system a conoco high frequency vibroseis unit was successfully used as the seismic source to generate the high frequencies necessary to detect and resolve the thin coal beds

acceleration creation and depletion of wind driven baroclinic rossby waves over an ocean ridge the influences of topography on the propagation spatial patterns and amplitude variations of long baroclinic rossby waves are investigated with a wind forced two layer model above a midocean ridge with steep topography the evolution equation for the baroclinic mode is shown to differ from that for a flat bottom in several ways 1 the phase speed is systematically faster by the factor h h2 where h is the total ocean depth and h2 is the lower layer thickness though the propagation remains westward and nearly nondispersive 2 an effectively dissipative transfer to the barotropic mode occurs whenever the baroclinic mode is locally parallel to f h contours where f is the coriolis frequency and 3 the wind forced response is amplified in proportion to the topographic steepness f h dh dx df dy for a longitudinally varying topography which can be a large factor but the amplification is only by the modest factor h h2 for a latitudinally varying topography effects 2 and 3 are the result of energy exchanges to and from the barotropic mode respectively effect 3 causes freely propagating baroclinic rossby waves to be generated west of the ridge these effects collectively cause distortions of the baroclinic wave pattern as it traverses the ridge these effects account qualitatively for several features seen in altimetric measurements in the vicinity of major topographic features an increase in variance of baroclinic signals on the west side an enhanced phase speed overall compared to flat bottom waves and an abrupt change in the phase speed at midocean ridges

the application of high resolution seismics in polish coal mining use of high resolution seismics were applied to the exploration and development of coal deposits in the upper silesian and the lublin coal basins in poland high resolution seismic surveys were carried out in various geological and mining conditions the objectives were to map commercial coal seams locate coal less zones and faults and solve some problems associated with mining conditions e g determining the height of caving roof zone theoretical modeling studies of seismic wave response for several geological models representing the coal basin structures were used to address these problems results from these successful surveys helped improved designs of new mines and or expand existing ones to provide more productive and safer coal mines

advances in seismic reflection profiling for us coal exploration the utilization of seismic reflection methods in us coal exploration increased during the last decade as evidenced by the number of publications and papers presented at technical meetings the increased application of innovative techniques adapted from the petroleum industry has resulted in improvements in seismic data acquisition processing and interpretation the objective of this paper is to present some advances in the application of high resolution seismic reflection methods to us coal exploration since they were adopted in the mid 1970s

new evidence on deglacial climatic variability from an alpine lacustrine record in northwestern yunnan province southwestern china abstract new deglacial pollen and conifer stoma records from tiancai lake northwestern yunnan province southwestern china an alpine lake in the southwest monsoon region are presented in this study based on these records the lithology of core tcyl1 and pca analysis of pollen data between 21 and 11 5 ka bp calibrated 14 c years the deglacial vegetation and climate changes are discussed in detail the results show that tiancai lake was above the upper limit of picea abies forest a treeline in the study area between 21 and 11 5 ka bp and the climate was colder and drier than that of the holocene during this period eight significant vegetation changes are recorded that are considered to be responses to changing temperatures and variations in the southwest monsoon in southwestern china the heinrich event 1 h1 the bolling allerod warm period ba and the younger dryas cold event yd are all clearly detected in this record in addition this study finds that the initial late glacial warming in northwestern yunnan province was at 18 7 ka bp which is coincident with the climate records in monsoonal central asia the indian ocean the tropical and subtropical pacific ocean and antarctica and is a response to solar insolation changes a noted temperature increase between 15 8 and 14 4 ka bp occurred at the end of the h1 and before the ba which indicates a strong pre bolling warming based on the study we consider that the hypothesis about a slowdown of the ocean s thermohaline circulation is sufficient to explain these late glacial abrupt events

effects of high resolution and spinup time on modeled north atlantic circulation abstractthe influence of a high horizontal resolution 5 15 km on the general circulation and hydrography in the north atlantic is investigated using the finite element sea ice ocean model fesom

properties of rossby waves in the north atlantic estimated from satellite data this study uses satellite observations of sea surface height ssh to detect westward propagating anomalies presumably baroclinic rossby waves in the north atlantic and to estimate their period wavelength amplitude and phase speed detection involved a nonlinear fit of the theoretical dispersion relation for rossby waves to the time longitude spectrum at a given latitude estimates of period wavelength and phase speed resulted directly from the detection process based on these a filter was designed and applied to extract the rossby wave signal from the data this allowed a mapping of the spatial variability of the rossby wave amplitude for the north atlantic results showed the familiar larger speed of observed rossby waves relative to that expected from theory with the largest differences occurring at shorter periods the data also show that the dominant rossby waves those with periods that are less than annual propagated with almost uniform speed in the western part of the north atlantic between 308 and 408n in agreement with previous studies the amplitude of the rossby wave field was higher in the western part of the north atlantic than in the eastern part this is often attributed to the influence of the mid atlantic ridge by contrast this study through an analysis of the wave spatial structure suggests that the source of the baroclinic rossby waves at midlatitudes in the western north atlantic is located southeast of the grand banks where the gulf stream and the deep western boundary current interact with the newfoundland ridge the spatial structure of the waves in the eastern north atlantic is consistent with the formation of these waves along the basin s eastern boundary

does the trigger for abrupt climate change reside in the ocean or in the atmosphere two hypotheses have been put forward to explain the large and abrupt climate changes that punctuated glacial time one attributes such changes to reorganizations of the ocean s thermohaline circulation and the other to changes in tropical atmosphere ocean dynamics in an attempt to distinguish between these hypotheses two lines of evidence are examined the first involves the timing of the freshwater injections to the northern atlantic that have been suggested as triggers for the global impacts associated with the younger dryas and heinrich events the second has to do with evidence for precursory events associated with the heinrich ice rafted debris layers in the northern atlantic and with the abrupt dansgaard oeschger warmings recorded in the santa barbara basin

monitoring the atlantic meridional overturning circulation the rapid climate change programme rapid has established a prototype system to continuously observe the strength and structure of the atlantic meridional overturning circulation moc at 26 5 n here we provide a detailed description of the rapid moc monitoring array and how it has evolved during the first four deployment years as well as an overview of the main findings so far the rapid moc monitoring array measures 1 gulf stream transport through florida strait by cable and repeat direct velocity measurements 2 ekman transports by satellite scatterometer measurements 3 deep western boundary currents by direct velocity measurements 4 the basin wide interior baroclinic circulation from moorings measuring vertical profiles of density at the boundaries and on either side of the mid atlantic ridge and 5 barotropic fluctuations using bottom pressure recorders the array became operational in late march 2004 and is expected to continue until at least 2014 the first 4 years of observations april 2004 april 2008 have provided an unprecedented insight into the moc structure and variability we show that the zonally integrated meridional flow tends to conserve mass with the fluctuations of the different transport components largely compensating at periods longer than 10 days we take this as experimental confirmation of the monitoring strategy which was initially tested in numerical models the moc at 26 5 n is characterised by a large variability even on timescales as short as weeks to months the mean maximum moc transport for the first 4 years of observations is 18 7 sv with a standard deviation of 4 8 sv the mechanisms causing the moc variability are not yet fully understood part of the observed moc variability consists of a seasonal cycle which can be linked to the seasonal variability of the wind stress curl close to the african coast close to the western boundary fluctuations in the gulf stream and in the north atlantic deep water nadw coincide with bottom pressure variations at the western margin thus suggesting a barotropic compensation ongoing and future research will put these local transport variations into a wider spatial and climatic context

interpretation of the propagation of surface altimetric observations in terms of planetary waves and geostrophic turbulence 1 the interpretation of surface altimetric signals in terms of rossby waves is revisited rather than make the long wave approximation the horizontal scale of the waves is adjusted to optimally fit the phase speed predicted by linear theory to that observed by altimetry assuming a first baroclinic mode vertical structure it is found that in the tropical band the observations can be fit if the wavelength of the waves is assumed to be large of order 600 km or so however poleward of 30 it is more difficult to fit linear theory to the observations and the fit is less good than at lower latitudes the required scale of the waves must be reduced to about 100 km somewhat larger than the local deformation wavelength it is argued that these results can be interpreted in terms of rossby wave baroclinic instability and turbulence theory at low latitudes there is an overlap between geostrophic turbulence and rossby wave timescales and so an upscale energy transfer from baroclinic instability at the deformation scale produces waves at high latitudes there is no such overlap and waves are not produced by upscale energy transfer these ideas are tested by using surface drifter data to infer turbulent velocities and timescales that are compared to those of linear rossby waves a transition from a field dominated by waves to one dominated by turbulence occurs at about 30 broadly consistent with the transition that is required to fit linear theory to altimetric observations

the canary basin contribution to the seasonal cycle of the atlantic meridional overturning circulation at 26 n this study examines the seasonal cycle of the atlantic meridional overturning circulation amoc and its eastern boundary contributions the cycle has a magnitude of 6 sv as measured by the rapid mocha wbts project array at 26 n which is driven largely by the eastern boundary the eastern boundary variations are explored in the context of the regional circulation around the canary islands there is a 3 month lag between maximum wind forcing and the largest eastern boundary transports which is explained in terms of a model for rossby wave generated at the eastern boundary two dynamic processes take place through the lanzarote passage lp in fall the recirculation of the canary current and the northward flow of the intermediate poleward undercurrent in contrast during the remaining seasons the transport through the lp is southward due to the canary upwelling current these processes are linked to the seasonal cycle of the amoc

slowing of the atlantic meridional overturning circulation at 25 n the atlantic meridional overturning circulation carries warm upper waters into far northern latitudes and returns cold deep waters southward across the equator its heat transport makes a substantial contribution to the moderate climate of maritime and continental europe and any slowdown in the overturning circulation would have profound implications for climate change a transatlantic section along latitude 25 n has been used as a baseline for estimating the overturning circulation and associated heat transport here we analyse a new 25 n transatlantic section and compare it with four previous sections taken over the past five decades the comparison suggests that the atlantic meridional overturning circulation has slowed by about 30 per cent between 1957 and 2004 whereas the northward transport in the gulf stream across 25 n has remained nearly constant the slowing is evident both in a 50 per cent larger southward moving mid ocean recirculation of thermocline waters and also in a 50 per cent decrease in the southward transport of lower north atlantic deep water between 3 000 and 5 000 m in depth in 2004 more of the northward gulf stream flow was recirculating back southward in the thermocline within the subtropical gyre and less was returning southward at depth

shallow seismic reflection investigations of coal in the sydney basin surface reflection profiling with the mini sosie technique successfully mapped shallow coal seam structure in the western sydney basin new south wales several minor faults and zones of fracturing were detected in regions of thick triassic sandstone cover data quality was poor and unsuitable for geologic interpretation synthetic seismograms based on nearby borehole and petrophysical control show excellent agreement with the mini sosie sections and illustrate the deleterious filtering effects of coal seams and sequences to establish a phenomenological basis for seismic wave propagation in shallow coal measures two vertical seismic profiles vsps which used small explosive charges were recorded with high spatial and temporal sampling numerous multiple reflections were observed in the downgoing wave display the isolated upgoing waves were migrated to yield blurred images of the main coal seams the subsurface velocity function also deduced from the vsp shows broad correlation with the geologic log

global observations of large oceanic eddies 1 ten years of sea surface height ssh fields constructed from the merged topex poseidon t p and ers 1 2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean the higher resolution of the merged dataset reveals that more than 50 of the variability over much of the world ocean is accounted for by eddies with amplitudes of 5 25 cm and diameters of 100 200 km these eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies respectively the vast majority of the eddies are found to be nonlinear

the evolution and propagation of quasigeostrophic ocean eddies abstractthe long term evolution of initially gaussian eddies is studied in a reduced gravity shallow water model using both linear and nonlinear quasigeostrophic theory in an attempt to understand westward propagating mesoscale eddies observed and tracked by satellite altimetry by examining both isolated eddies and a large basin seeded with eddies with statistical characteristics consistent with those of observed eddies it is shown that long term eddy coherence and the zonal wavenumber frequency power spectral density are best matched by the nonlinear model individual characteristics of the eddies including amplitude decay horizontal length scale decay and zonal and meridional propagation speed of a previously unrecognized quasi stable state are examined the results show that the meridional deflections from purely westward flow poleward for cyclones and equatorward for anticyclones are consistent with satellite observations examination of the fluid transport properties of the eddies shows that an

seismic reflection imaging of thin kimberlite dykes and sills exploration and deposit characterization of the snap lake dyke canada abstract seismic reflection techniques are for the first time used to image a thin diamondiferous kimberlite dyke from subcrop to depths greater than 1300 m exploration for vertical kimberlite pipes generally utilizes potential field techniques that often fail to reveal subhorizontal or shallow dipping intrusions in contrast seismic reflection methods are well suited for imaging targets with this geometry therefore in order to evaluate seismic reflection as a tool for subhorizontal kimberlite dyke sill exploration and mine planning a feasibility study and subsequent seismic survey were undertaken on the diamondiferous snap lake dyke northwest territories canada a substantial drilling program has mapped the dyke as a gently dipping sheet that averages 2 3 m in thickness the detailed structural and composition data available at snap lake provides a unique opportunity to test reflection techniques on a well sampled deposit the feasibility study involved measuring p velocities and densities of cores drilled from the kimberlite and host rocks these data were used to model reflection amplitudes evaluate resolution limitations and determine the acquisition parameters for the reflection survey two 2 d lines were acquired that provide comparative datasets for different sources explosive and vibroseis and ground types land and lake ice in addition the exploration scale survey incorporated high fold 40 260 nominal and long offsets 3260 m the explosive source profile recorded on land yielded a superb image of the dyke from depths of 60 m to more than 1300 m over a lateral distance of 5700 m the seismic image correlates well with adjacent drill hole data and adds considerable detail to the topography of the kimberlite sheet determined by drilling the vibroseis source also imaged the dyke but only when sources and geophones were on land the dyke was not imaged beneath the ice due to reverberation and attenuation effects the frequency response and unusually strong reflection amplitudes from the dyke indicate the importance of tuning effects and multiples for this type of target and acquisition environment apparent correlations between reflection amplitudes and dyke structure e g thickness feathering 3 d geometry suggest that seismic reflection data may be valuable for guiding drilling programs the results demonstrate that in the appropriate situation seismic methods have great potential for use in kimberlite exploration subsurface mapping and detailed imaging for mine development purposes

a means of estimating the intrinsic and atmospherically forced contributions to sea surface height variability applied to altimetric observations drawing on a 50 member ocean ensemble hindcast the magnitude and characteristic temporal and spatial scales of intrinsic and forced sea surface height ssh variability are evaluated over a 37 year period the intrinsic and forced contributions derived from the ensemble are found to have similar temporal spectra but different characteristic spatial scales these results suggest that with an appropriate choice of cutoff scales simple spatial filtering can be used to estimate the forced and intrinsic contributions given either a single model run or an observational data set the method is tested using a single member drawn from the ensemble before being applied to the observed altimetric record two sample applications with relevance to large scale climate are used to illustrate the method s potential utility firstly the long term trends calculated from the total and recreated forced components using the altimetric record are compared and local differences highlighted second the recreated forced ssh is shown to covary with the north atlantic oscillation at seasonal time scales in regions where no such influence can be found using the original ssh signal some limitations and uses for which the method may prove unsuitable are also briefly considered

fluvial systems of upper cretaceous mesaverde group and paleocene north horn formation central utah record of transition from thin skinned deformation in foreland region abstract nonmarine strata of the upper part of the mesaverde group and north horn formation exposed between the wasatch plateau and the green river in central utah record a late campanian tectonic transition from thrust belt deformation to basement cored uplift mesaverde group sediments were deposited by synorogenic braided and meandering rivers during most of campanian time sediment transport was east and northeast away from the thrust belt across a fluvial coastal plain subsequent development of the san rafael swell a basement uplift between western and eastern localities caused erosional thinning of the section sandstones within the upper part of the mesaverde group form two distinct compositional suites a lower quartzose petrofacies and an upper lithic petrofacies lithic grain populations of the upper petrofacies are dominated by sedimentary rock fragments on the west and volcanic rock fragments on the east sedimentary lithic grains were derived from the thrust belt whereas volcanic lithic grains were derived from a volcanic terrane to the southwest tributary streams carrying quartzose detritus from the thrust belt entered a northeast flowing trunk system and caused a basinward dilution of volcanic detritus disappearance of volcanic grains and local changes in paleocurrent directions in latest campanian time reflect initial growth of the san rafael swell and development of an intermon ane trunk tributary fluvial system depositional onlap across the mesaverde group by the post tectonic north horn formation indicates a minimum late paleocene age for uplift of the san rafael swell end of article last page 854

the destruction of lenses and generation of wodons abstract since midocean eddies migrate westward they eventually reach the western boundaries it is therefore of interest to find out what happens after the eddies collide with the walls an isopycnic two layer primitive equation model on a plane and a simple analytical model on an f plane are constructed to investigate the meridional migration of an oceanic eddy along a western wall on a plane three factors determine the eddy s migration along a western meridional wall first the image effect pushes an anticyclonic cyclonic eddy northward southward second the force resulting from the larger coriolis force on the northern side of the eddy pulls an anticyclonic cyclonic eddy southward northward third after an anticyclonic cyclonic eddy collides with the wall parts of the anticyclonic eddy s interior fluid leak out southward northward along the wall forming a thin jet in an analogy to a rocket this jet pushes the eddy northward southward our aim is to investigate in whi

observed interannual variability of the atlantic meridional overturning circulation at 26 5 n the atlantic meridional overturning circulation moc plays a critical role in the climate system and is responsible for much of the heat transported by the ocean a mooring array nomianally at 26 circ n between the bahamas and the canary islands deployed in apr 2004 provides continuous measurements of the strength and variability of this circulation with seven full years of measurements we now examine the interannual variability of the moc while earlier results highlighted substantial seasonal and shorter timescale variability there had not been significant interannual variability the mean moc from 1 apr 2004 to the 31 march 2009 was 18 5 sv with the annual means having a standard deviation of only 1 0 sv from 1 april 2009 to 31 march 2010 the annually averaged moc strength was just 12 8 sv representing a 30 decline this downturn persisted from early 2009 to mid 2010 we show that the cause of the decline was not only an anomalous wind driven event from dec 2009 mar 2010 but also a strengthening of the geostrophic flow in particular the southward flow in the top 1100 m intensified while the deep southward return transport particularly in the deepest layer from 3000 5000 m weakened this rebalancing of the transport from the deep overturning to the upper gyre has implications for the heat transported by the atlantic

interannual variability of antarctic intermediate water in the tropical north atlantic interannual variability of antarctic intermediate water aaiw in the tropical north atlantic is investigated using the gecco2 ocean state estimate and argo data aaiw salinity variability near the western boundary is highly correlated with the transport along the western boundary on interannual timescales northward propagating anomalies are associated with the western boundary transport variability that to some extent is related to the large scale wind stress curl forcing by means of the sverdrup balance aaiw anomalies also propagate westward with the speed of baroclinic rossby waves indicating that the displacement of the meridional salinity gradient by westward propagation of baroclinic rossby waves plays a role in the variability of aaiw characteristics slower eastward spreading of aaiw anomalies is identified on decadal timescales likely associated with the advection of salinity anomalies by weak eastward current bands understanding the observed interannual and decadal variability of aaiw salinity is important to properly interpret salinity changes reported in response to changes in the hydrological cycle

feasibility of cdp seismic reflection to image structures in a 220 m deep 3 m thick coal zone near palau coahuila mexico the common depth point cdp seismic reflection method was used to delineate subsurface structure in a 3 m thick 220 m deep coal zone in the palau area of coahuila mexico an extensive series of walkaway noise tests was performed to optimize recording parameters and equipment reflection events can be interpreted from depths of approximately 100 to 300 m on cdp stacked seismic sections the seismic data allow accurate identification of the horizontal location of the structure responsible for a drill discovered 3 m difference in coal zone depth between boreholes 150 m apart the reflection method can discriminate folding with wavelengths in excess of 20 m and faulting with offset greater than 2 m at this site

coal prospect evaluation using high resolution reflection seismology a case study high resolution seismic reflection profiling can be used to evaluate detailed structural and stratigraphic features of coal prospects since most coal prospects are relatively shallow less than 600 m deep the vertical and lateral resolution of seismic data can be significantly improved by high sampling rates in space and time the following case study shows the effective use of seismic data in evaluation of the wyodak coal at a prospective coal gasification site the data were used to map the detailed structure and thickness of the coal and to search for lateral discontinuities such as pinchouts and faults an important find was a paleochannel cutting across the base of the coal seam which was later confirmed by drilling

field comparison of shallow p wave seismic sources near houston texas a shallow p wave seismic source comparison was conducted at a site near houston texas where the depth to the water table was approximately 7 m and near surface materials consisted of clays sands and gravels data from twelve different sources during this november 1991 comparison are displayed and analyzed reflection events are interpretable at about 40 ms on some 220 hz analog low cut filtered field files and at 60 ms on most 110 and 220 hz analog low cut filtered field files calculations and local water well information suggest the 40 ms event is from the top of the water table subsurface explosive sources seem to possess the highest dominant frequency broadest bandwidth and recorded amplitudes and therefore have the greatest resolution potential at this site our previous work and that of our colleagues suggests that given a specific set of site characteristics any source could dominate the comparison categories addressed here

geology and thermal maturity of namurian deposits in the němcicky sub basin as the south eastern continuation of the upper silesian coal basin czech republic abstract the southernmost documented occurrences of namurian coal bearing strata can be found in the n mcicky area se moravia that is considered to be the southern continuation of the upper silesian coal basin since the south eastern moravia belongs to the most prospective areas in terms of hydrocarbon exploration and production in the czech republic and namurian deposits are considered to be one of the potential source rocks there was a systematic evaluation of the southernmost occurrence of coal bearing carboniferous deposits in the czech republic during the hydrocarbon exploration within the area with regard to the regional geological setting and thermal maturity 2d and high quality 3d seismic surveys were used for a detailed thermal maturation analysis and a determination of the regional situation of heavily faulted eroded namurian strata cores and cuttings of coal and siltstones were used from 8 boreholes to investigate and measure the vitrinite reflectance the lithology and petrography definition was also done based on thin sections all new measurements were compared with archived data and older studies in the n mcicky sub basin the complete sedimentary succession occurs as part of typical cyclic development starting with basal conglomerates and followed by sandstones alternating with claystones siltstones and coal seams of marine and transitional origin samples from the nikolcice kurd jov ridge are showing significantly lower vitrinitte reflectance values with respect to their depths than those from the nesvacilka graben this fact is supporting the distinctive lateral movement along the western nesvacilka fault as presumed from the seismic interpretation dominant source from immature orogen is combined with the source from the mature continetal block i e opposite margin of the basin the seismic interpretation shows that the thicknesses of namurian deposits are not decreasing at all towards the recently deeper positions accordingly it is suggested that it is right within this erosionally untouched accommodational space of the n mcicky sub basin where we can find the interconnection to the uscb in the north

westward propagating sst anomaly features in the sargasso sea 1982 88 abstract sea surface temperature ts maps of the region from 59 5 to 75 5 w 22 5 to 33 5 n containing the western north atlantic subtropical convergence zone stcz were derived from avhrr 2 images the 7 year mean annual cycle was removed and the maps were filtered in space and time to represent anomaly variability with wavelengths 220 km and periods 50 days warm and cold anomaly features were observed cast of 71 w between 26 and 32 n that propagated westward at 3 4 km day 1 and that occasionally exceeded 1 c in amplitude they are generally strong and persistent from fall to spring and are only marginally detectable during summer during 1981 82 1982 83 and 1985 86 individual features could be followed through the entire fall spring interval during 1983 84 1986 87 and 1987 88 they could typically be followed for 2 4 months and during 1984 85 for only 1 2 months the features were anisotropic during all fall spring intervals except 1986 87 and they had characteristic wavelengths of 80

temporal variability of the atlantic meridional overturning circulation at 26 5 n the vigor of atlantic meridional overturning circulation moc is thought to be vulnerable to global warming but its short term temporal variability is unknown so changes inferred from sparse observations on the decadal time scale of recent climate change are uncertain we combine continuous measurements of the moc beginning in 2004 using the purposefully designed transatlantic rapid climate change array of moored instruments deployed along 26 5 n with time series of gulf stream transport and surface layer ekman transport to quantify its intra annual variability the year long average overturning is 18 7 5 6 sverdrups sv range 4 0 to 34 9 sv where 1 sv a flow of ocean water of 106 cubic meters per second interannual changes in the overturning can be monitored with a resolution of 1 5 sv

locating faults in underground coal mines using high resolution seismic reflection techniques a high resolution seismic reflection technique was used to locate faults in coal seams that were not visible on the surface and could only be observed in underground coal mines an 8 gauge buffalo gun built by the research and development department of consolidation coal company was used as the seismic source the coal seam at a depth of 700 ft produces a reflection with a predominant frequency of about 125 hz the high resolution seismic data permitted faults with vertical displacements of the same magnitude as the seam thickness to be detected at depths of several hundred feet beneath the surface several faults were detected and interpreted from the seismic sections and the magnitudes of their displacement were estimated by matching the recorded seismic data to synthetic seismic data subsequent underground mine development in the study area confirmed two interpreted faults and their estimated displacements mining engineers were able to use the information provided by the seismic survey to plan an

can thin coals be resolved in seismic data an example of the challenges for carboniferous visean to westphalian source rock definition across the elbow spit platform netherlands and the mid north sea high uk through well synthetic modelling