unsaturated zone characterization in soil through transient wetting and drying using gpr joint time frequency analysis and grayscale images summary this paper describes an experimental method to characterize the soil s unsaturated zone by constructing a scenario in which transient downward water infiltration took place from the topsoil to the bottom soil continuously during the water infiltration gpr waveforms and side view grayscale images of the soil column were simultaneously and continuously captured the gpr wavelets associated with the wetting front were analyzed using short time fourier transform stft algorithm the downward wetting front and the stretch of unsaturated transition zone decelerated and eased the wetting front s reflection in the time domain as well as reduced the peak frequency and attenuated the frequency spectra in the frequency domain the subsequent drying process further attenuated but accelerated the wetting front s reflection in both time and frequency domains these observations were correlated with the image pixel profiles from which gpr velocity profiles at different lapsed times were generated after computation via a complex refractive index model crim the crim method is entirely non invasive and not only offers very detailed measurement of the water saturation profile of the transition zone in laboratory scale but also is potentially useful for the further study of a variety of vadose zone properties

joint inversion of full waveform ground penetrating radar and electrical resistivity data part 2 enhancing low frequencies with the envelope transform and cross gradientsjoint inversion of gpr and er data recovering material properties of the subsurface using ground penetrating radar gpr data of finite bandwidth with missing low frequencies and in the presence of strong attenuation is a challengi

complex dielectric permittivity measurements from ground penetrating radar data to estimate snow liquid water content in the pendular regime 1 monitoring the snow water equivalent swe is critical to effective management of water resources in many parts of the world that depend on the mountain snowpack for water storage there are currently no methods to remotely sense swe with accuracy over large lateral distances in the steep and often forested terrain of mountain basins previous studies have shown that measurements of ground penetrating radar gpr velocity can provide accurate estimates of swe in dry snow introduction of liquid water into the snowpack results in a three phase system that cannot be accurately characterized with gpr velocity alone we show that measuring the frequency dependent gpr signal attenuation and velocity provides a direct estimate of the complex dielectric permittivity because the imaginary component is a function only of liquid water content we can utilize both the real and imaginary components of the permittivity to estimate liquid water content snow density and swe using existing empirical relationships that are valid in the pendular regime we tested this new method at two field sites and found that the estimates were accurate to within 12 of gravimetric methods in both a moist and a dry snowpack gpr has the potential to provide swe estimates across large lateral distances over a broad range of snow conditions

effects of the transition zone above a water table on the reflection of gpr waves 1 we simulate two levels of water table at 72 and 48 cm depth by injecting water in a sand box that also contains several buried objects gpr profiles acquired with a 1200 mhz antenna at the top of the sand box do not show any clear reflections from the water table this is because of the existence of a transition zone in which the velocity is a continuously decreasing function of depth the reflection coefficient in this case decreases with increasing frequency and even vanishes for a cut off frequency f0 which itself increases with decreasing transition zone thickness by modeling in the frequency domain we explain the absence of the high frequency gpr reflections from the top of the saturated zone when the wavelength is small high frequency compared to the thickness of the transition layer the reflection coefficient is negligible and hence no reflections from the water table will be observed

a field scale study of pumping induced drainage and recovery in an unconfined aquifer abstract an aquifer test involving seven days of pumping and five days of recovery was performed in the unconfined aquifer at canadian forces base borden in ontario canada hydraulic head levels were intensively monitored in eleven observation wells and moisture content profiles were frequently logged using a neutron moisture probe at six different radial distances from the pumping well capillary fringe thickness variations were inferred by comparing these hydraulic and moisture content measurements allowing for the effects of lithologic variations the response of the moisture content profile is predominately characterized by a downward translation during pumping induced drainage our observations indicate that there is minimal excess storage above the capillary fringe at late times the capillary fringe extended significantly with pumping in comparison to its static thickness this extension progressively increased during the entire test the capillary fringe extension decreased with increasing radial distance and was inferred to have eventually extended out to between 20 and 25 m this extension represented a significant volume of excess capillary fringe storage that persisted into late times a direct relationship between the vertical gradients below the water table and the excess capillary fringe storage is not apparent from these experimental data analogous to the pumping test observations the response of the moisture content profile during recovery is essentially an upward translation while the hydraulic head levels recovered nearly to their pre pumping elevations the moisture content profiles stabilized approximately 0 20 m below their pre pumping positions this recovery differential leads to a capillary fringe compression that converted excess storage during pumping into storage deficit during recovery in contrast to the significant radial variation of the capillary fringe extension during pumping the capillary fringe compression is relatively uniform out to at least 15 m during the late recovery stage the recovery deficit and entrapped residual air observed below the upward translating transition zone are strong indications that significant hysteretic processes are occurring at the field scale

uniqueness and stability analysis of hydrogeophysical inversion for time lapse ground penetrating radar estimates of shallow soil hydraulic properties precise measurement of soil hydraulic properties at field scales is one of the prerequisites to simulate subsurface flow and transport processes which is crucial in many research and engineering areas in our study we numerically analyze uniqueness and stability for integrated hydrogeophysical inversion of time lapse off ground ground penetrating radar gpr data in estimating the unsaturated soil hydraulic properties in the inversion hydrodynamic modeling based on the one dimensional 1 d richards equation is used to physically constrain a full waveform radar electromagnetic model synthetic gpr data in terms of 3 d multilayered media green s functions were generated for three different textured soils coarse medium and fine and assuming different infiltration events inversion was performed iteratively to estimate three key soil hydraulic parameters n and ks of the mualem van genuchten model using the global multilevel coordinate search optimization algorithm for the coarse and medium textured soils inversions converged to the actual solution for all scenarios for the fine soil estimation errors occurred mainly because of the higher attenuation of the electromagnetic waves in such a soil high electric conductivity the procedure appeared to be generally stable with respect to possible errors in the hydrodynamic and petrophysical model parameterization however we found that particular attention should be given to an accurate estimation of the saturated water content and infiltration flux for real field applications the results from our numerical experiments suggest that in theory the proposed method is promising for the noninvasive identification of the shallow soil hydraulic properties at the field scale with a high spatial resolution

georadar derived estimates of firn density in the percolation zone western greenland ice sheet 1 greater understanding of variations in firn densification is needed to distinguish between dynamic and melt driven elevation changes on the greenland ice sheet this is especially true in greenland s percolation zone where firn density profiles are poorly documented because few ice cores are extracted in regions with surface melt we used georadar to investigate firn density variations with depth along a 70 km transect through a portion of the accumulation area in western greenland that partially melts we estimated electromagnetic wave velocity by inverting reflection traveltimes picked from common midpoint gathers we followed a procedure designed to find the simplest velocity versus depth model that describes the data within estimated uncertainty on the basis of the velocities we estimated 13 depth density profiles of the upper 80 m using a petrophysical model based on the complex refractive index method equation at the highest elevation site our density profile is consistent with nearby core data acquired in the same year our profiles at the six highest elevation sites match an empirically based densification model for dry firn indicating relatively minor amounts of water infiltration and densification by melt and refreeze in this higher region of the percolation zone at the four lowest elevation sites our profiles reach ice densities at substantially shallower depths implying considerable meltwater infiltration and ice layer development in this lower region of the percolation zone the separation between these two regions is 8 km and spans 60 m of elevation which suggests that the balance between dry firn and melt induced densification processes is sensitive to minor changes in melt

early mesozoic southward subduction history of the mongol okhotsk oceanic plate evidence from geochronology and geochemistry of early mesozoic intrusive rocks in the erguna massif ne china abstract in this paper we present new zircon u pb ages hf isotope data and whole rock major and trace element data for early mesozoic intrusive rocks in the erguna massif of ne china and we use these data to constrain the history of southward subduction of the mongol okhotsk oceanic plate and its influence on ne china as a whole the zircon u pb dating indicates that early mesozoic magmatic activity in the erguna massif can be subdivided into four stages at 246 ma 225 ma 205 ma and 185 ma the 246 ma intrusive rocks comprise a suite of high k calc alkaline diorites quartz diorites granodiorites monzogranites and syenogranites with i type affinities the 225 ma intrusive rocks consist of gabbro diorites and granitoids and they constitute a bimodal igneous association the 205 ma intrusive rocks are dominated by calc alkaline i type granitoids that are accompanied by subordinate intermediate mafic rocks the 185 ma intrusive rocks are dominated by i type granitoids accompanied by minor amounts of a types these early mesozoic granitoids mainly originated by partial melting of a depleted and heterogeneous lower crust whereas the coeval mafic rocks were probably derived from partial melting of a depleted mantle modified by subduction related fluids the rock associations and their geochemical features indicate that the 246 ma 205 ma and 185 ma intrusive rocks formed in an active continental margin setting related to the southward subduction of the mongol okhotsk oceanic plate the 225 ma bimodal igneous rock association formed within an extensional environment in a pause during the subduction process of the mongol okhotsk oceanic plate every magmatic stage has its own corresponding set of porphyry deposits in the southeast of the mongol okhotsk suture belt taking all this into account we conclude the following 1 during the early mesozoic the mongol okhotsk oceanic plate was subducted towards the south beneath the erguna massif but with a pause in subduction at 225 ma and 2 the southward subduction of the mongol okhotsk oceanic plate not only caused the intense magmatic activity but was also favorable to the formation of porphyry deposits

the influence of beach porosity on wave uprush and backwash abstract packwood a r 1983 the influence of beach porosity on wave uprush and backwash coastal eng 7 29 40 a numerical model is described to calculate the influence of a porous bed on the run up of a bore on a gently sloping sandy beach it is shown that fine medium grade sands have very little effect in the run up phase significant differences between impermeable and porous bed solutions are found in the backwash which might explain certain sand erosion and deposition phenomena

acquisition and processing of wide aperture ground penetrating radar data a 40 channel wide aperture ground penetrating radar gpr data set was recorded in a complicated fluvial aeolian environment in eastern canada the data were collected in the multichannel format usually associated with seismic reflection surveys and were input directly into a standard seismic processing sequence filtering static corrections common midpoint gathering velocity analysis normal and dip moveout corrections stacking and depth migration the results show significant improvements over single channel recordings in noise reduction and depth of penetration by stacking and in spatial positioning and reduction of diffraction artifacts by migration these characteristics increase the potential for reliable interpretation of structural and stratigraphic details thus without having to develop any new software gpr data processing technology is brought to the same level of capability flexibility and accessibility that is current in seismic exploration

a comparison of seismic and radar methods to establish the thickness and density of glacier snow cover we show that geophysical methods offer an effective means of quantifying snow thickness and density opportunistic efficient but non optimized seismic refraction and ground penetrating radar gpr

generation of sodium rich magmas from newly underplated basaltic crust sodium rich rocks of trondhjemite tonalite dacite ttd or granodiorite ttg suites form much of precambrian continental crust1 they are thought to have formed by partial melting of subducted oceanic crust2 3 a process that would have been much more widespread early in earth history than at present owing to the higher thermal gradients prevailing at that time4 phanerozoic ttd suites do exist however and seem also to relate to subduction zones5 defant and drummond6 proposed that these suites form where young 25 myr hot oceanic lithosphere is subducted and melts thus locally simulating the conditions that led to widespread crustal growth in the archaean here we describe plutonic and volcanic rocks from the cordillera blanca complex in peru which have characteristics of the high al ttd suite but which were produced above a subduction zone containing a 60 myr old slab we present evidence that the complex formed by partial melting of newly underplated basaltic crust and argue that this mechanism should be considered more generally as an additional way of generating sodium rich arc magmas

triassic volcanism in eastern heilongjiang and jilin provinces ne china chronology geochemistry and tectonic implications abstract with the aim of constraining the early mesozoic tectonic evolution of the eastern section of the central asian orogenic belt caob we undertook zircon u pb dating and geochemical analyses major and trace elements sr nd isotopes of volcanic rocks of the luoquanzhan formation and daxinggou group in eastern heilongjiang and jilin provinces china the analyzed rocks consist mainly of dacite and rhyolite with sio2 contents of 68 52 76 65 wt three samples from the luoquanzhan formation and one from the daxinggou group were analyzed using laser ablation inductively coupled plasma mass spectrometry la icp ms u pb zircon techniques three zircons with well defined oscillatory zoning yielded weighted mean 206pb 238u ages of 217 1 214 2 and 208 1 ma and one zircon with oscillatory zoning yielded a weighted mean 206pb 238u age of 201 1 ma these ages are interpreted to represent the timing of eruption of the volcanic rocks the triassic volcanic rocks are characterized by high sio2 and low mgo concentrations enrichment in large ion lithophile elements liles and light rare earth elements lrees depletion in high field strength elements hfses and heavy rare earth elements hrees 87sr 86sr i 0 7040 0 7050 luoquanzhan formation and 0 7163 0 7381 daxinggou group and end t 1 89 3 94 luoquanzhan formation and 3 42 3 68 daxinggou group these geochemical features indicate an origin involving the partial melting of juvenile lower crust nd model ages tdm2 of 651 821 ma and that compositional variation among the volcanic rocks arose from mineral fractionation and minor assimilation these volcanic rocks formed within an extensional environment following collision of the ncc and jiamusi khanka massif during the late paleozoic early triassic

the non invasive characterization of pumping induced dewatering using ground penetrating radar abstract ground penetrating radar gpr profiling is a non invasive geophysical technique that has been used by endres et al ground water 38 2000 566 to successfully image pumping induced drainage in an unconfined aquifer however the drained water volume calculated from the gpr data was significantly less than the actual pumped volume to investigate the reasons for this discrepancy a seven day pumping test and five day recovery test was performed at canadian forces base borden in ontario canada a dense spatial coverage of gpr profiles was used to better quantify variations in drainage due to small scale aquifer heterogeneity in addition a neutron moisture content probe was used to directly observe drainage and the soil moisture profile at a sealed well near the pumping well neutron logging indicated that the transition zone translated downward during pumping without undergoing significant extension comparison of the gpr and neutron derived transition zone drawdowns show nearly equal responses both of these observations support the hypothesis that the behaviour of the gpr reflection is an accurate measure of the transition zone response in contrast transition zone drawdown obtained from both gpr and neutron logging are significantly delayed relative to potentiometric drawdown resulting in an extended capillary fringe the drained water volume was determined from the gpr derived transition zone drawdown data using a number of different approaches methods that incorporated information about spatial variations in drainage gave larger estimates of drained water volume however those estimates were still lower than the actual pumped volume the unaccountable volume of water could be a result of several factors aquifer heterogeneity may still not be adequately represented by the increased gpr coverage and or leakage from the underlying aquitard may be providing a significant volume of water

physically based model of downstream fining in bedrock streams with lateral input 1 bed load particles in bedrock streams receiving lateral input from hillslopes may or may not show a clear monotonic pattern of size reduction in the downstream direction both abrasion and selective sorting may play important roles in generating downstream fining the objective of this study is to develop a physically based model of downstream fining in bedrock streams with lateral input based on both processes a surface based gravel transport relation for the size mixture is employed to account for the effect of selective sorting differential transport while the model produces silt and sand by abrasion it is also assumed to loosely capture particle fracturing via a lumped abrasion coefficient embodied in sternberg s law the model is here tested against field data from vieux habitants river in guadeloupe island which is located in the caribbean sea the river shows clear downstream fining and this pattern is captured reasonably well by the model the model results indicate that abrasion including fracturing is solely responsible for the downstream fining pattern for most of the study reach of the vieux habitants river sensitivity analysis of the model has also been performed the model results suggest that in general selective sorting by differential transport can play a role in downstream fining only in cases of streams with relatively fine gravel sizes and lower slopes the results also indicate that abrasion including fracturing and selective sorting can be equally important for downstream fining in bedrock rivers the results also suggest that future work should explicitly consider fracturing comminution separately from abrasion wear rather than lumping them in a sternberg type coefficient

radar reflections and water content estimation of aeolian sand dune many ground penetrating radar gpr profiles acquired on the dry aeolian environment have shown a strong reflectivity inside the present day dunes changes in water content are believed to be the origin of this reflectivity in this paper we try to model the radar reflections coming from the bottom of a dry aeolian dune by using the 1d wavelet modeling method the principle of this method is to calculate the effects of the propagation absorption dispersion and geometrical spreading and reflection on a reference wavelet for different values of various parameters and the best fit between the observed and calculated data leads to the optimum set of parameters by combining the wavelet modeling method with a semi empirical mixing formula for the bulk permittivity of moist sandy soils we estimate the water content and explain the importance of this latter parameter on reflection coefficient and on wavelet modeling

re os ages for the shameika porphyry mo deposit and the lipovy log rare metal pegmatite central urals russia the ages for pegmatite rare metal and beryl emerald deposits as well as porphyry mo deposits in the hercynian uralide orogen are not well known five molybdenite samples from the lipovy log pegmatite ta nb mo deposit and 11 molybdenite samples from the shameika porphyry mo deposit were selected for re os dating both mineral occurrences are spatial temporally associated with the adui composite granite pluton a well known rare metal related granite intrusion a re os isochron age of 262 0 7 3 ma was obtained for the lipovy log pegmatite ta nb mo deposit the shameika porphyry mo deposit associated with the malyshevo leucogranitic stock and surrounding hornfels provided isochron ages of 273 5 and 282 6 ma for two groups of molybdenite within stock and within hornfels all of these re os ages are consistent with presumed hercynian ages for the granite intrusions formed in a post collisional setting within the uralide orogen

wave field migration as a tool for estimating spatially continuous radar velocity and water content in glaciers 1 normal moveout velocity analysis can lead to significant overestimates of the velocity structure of temperate glaciers since most englacial reflectors approximate point scatters and violate the assumption of planar flat lying reflectors migration velocity analysis mva is a tool that does not depend on the assumption of flat lying reflectors mva can provide laterally and vertically continuous velocity estimates from conventional common offset radar sections in a study of temperate bench glacier alaska we used mva coupled with dielectric modeling to estimate the distribution of water content along a cross section of the glacier we found the glacier has two layers an upper layer with relatively low water content and lower layer with relatively high water content the ability to quantify hydrostratigraphy is important in understanding water storage and routing within glaciers

estimating snow water equivalent over long mountain transects using snowmobile mounted ground penetrating radar abstractthe water balance in alpine watersheds is dominated by snowmelt which provides infiltration recharges aquifers controls peak runoff and is responsible for most of the annual water flow downstream accurate estimation of snow water equivalent swe is necessary for runoff and flood estimation but acquiring enough measurements is challenging due to the variability of snow accumulation ablation and redistribution at a range of scales in mountainous terrain we have developed a method for imaging snow stratigraphy and estimating swe over large distances from a ground penetrating radar gpr system mounted on a snowmobile we mounted commercial gpr systems 500 and 800 mhz to the front of the snowmobile to provide maximum mobility and ensure that measurements were taken on pristine snow images showed detailed snow stratigraphy down to the ground surface over snow depths up to at least 8 m enabling the elucidation of snow accumulation and redistribution processes we estimated snow density an

delineation of macroporous zones in the unsaturated portion of the miami limestone using ground penetrating radar miami dade county florida summary the atlantic coastal ridge in dade county is an ooid shoal formed during the late pleistocene the ridge is composed of the eogenetic karst miami limestone characterized by a heterogeneous distribution of porosity that can manifest as large touching vug macroporous features with sizes in the meters and tens of meters direct evidence for the presence of such large dissolution features is only visible when exposed to the surface which may be problematic in urbanized areas for that reason it is critical to detect any potential precursors for such dissolution features at the subsurface level the purpose of this study was to investigate the ability of ground penetrating radar to detect areas of macroporosity by quantifying changes in electromagnetic wave velocity and relate them to changes in porosity after application of the complex refractive index model crim in order to constrain volumetric water content vwc in the crim an experiment using miami limestone samples was designed to understand 1 the range of typical vwcs and 2 the effect of capillary fringe on water table elevation the results show several areas where increases in em wave travel time associated with contrasts in porosity exceeding 40 cannot be explained by changes in vwcs typically shown in the miami limestone this study may help understand porosity variability in the unsaturated part of the miami limestone and if expanded to larger scales may aid groundwater flow models by better capturing distributions of macroporous areas that may contribute to direct recharge of the biscayne aquifer

end of winter snow depth variability on glaciers in alaska a quantitative understanding of snow thickness and snow water equivalent swe on glaciers is essential to a wide range of scientific and resource management topics however robust swe estimates are observationally challenging in part because swe can vary abruptly over short distances in complex terrain due to interactions between topography and meteorological processes in spring 2013 we measured snow accumulation on several glaciers around the gulf of alaska using both ground and helicopter based ground penetrating radar surveys complemented by extensive ground truth observations we found that swe can be highly variable 40 difference over short spatial scales tens to hundreds of meters especially in the ablation zone where the underlying ice surfaces are typically rough elevation provides the dominant basin scale influence on swe with gradients ranging from 115 to 400 mm 100 m regionally total accumulation and the accumulation gradient are strongly controlled by a glacier s distance from the coastal moisture source multiple linear regressions used to calculate distributed swe fields show that robust results require adequate sampling of the true distribution of multiple terrain parameters final swe estimates comparable to winter balances show reasonable agreement with both the parameter elevation relationships on independent slopes model climate data set 9 36 difference and the u s geological survey alaska benchmark glaciers 6 36 difference all the glaciers in our study exhibit substantial sensitivity to changing snow rain fractions regardless of their location in a coastal or continental climate while process based swe projections remain elusive the collection of ground penetrating radar gpr derived data sets provides a greatly enhanced perspective on the spatial distribution of swe and will pave the way for future work that may eventually allow such projections

linking growth episodes of zircon and metamorphic textures to zircon chemistry an example from the ultrahigh temperature granulites of rogaland sw norway in situ u th pb analyses by ion microprobe on zircon in intact textural relationships are combined with backscatter and cathodoluminescence imaging and trace element analyses to provide evidence for growth episodes of zircon this approach helps a to unravel the polymetamorphic history of aluminous migmatitic and granitoid gneisses of the regional contact aureole around the rogaland anorthosite norite intrusive complex and b to constrain the age of m 2 ultrahigh temperature uht metamorphism and the subsequent retrograde m 3 event all samples yield magmatic inherited zircon of c 1035 ma some an additional group at c 1050 ma this suggests that loss of pb by volume diffusion in non metamict zircon is not an important factor even under extreme crustal conditions furthermore the identical inheritance patterns in aluminous garnet cordierite osumilite bearing migmatites and orthogneisses indicate a metasomatic igneous instead of a sedimentary protolith for the migmatite results for the m 1 metamorphic event at c 1000 ma bp are consistent in all samples including those from outside the orthopyroxene in isograd the latter do not show evidence for zircon growth during the m 2 metamorphic episode zircon intergrown with or included within m 2 metamorphic minerals magnetite spinel orthopyroxene give an age of 927 7 ma 2 n 20 the youngest observed results are found in zircon outside m 2 minerals some overgrown by m 3 mineral assemblages late garnet coronas garnet quartz and orthopyroxene garnet symplectites and yield a slightly younger pooled age of 908 9 ma 2 n 6 these textures are relative time markers for the crystallization of zircon overgrowths during discrete stages of the uht event these youngest age groups are consistent with the emplacement age of the rogaland intrusive complex and the last magmatic activity tellnes dyke intrusion respectively this is direct and conclusive evidence for uht metamorphism in the regional aureole being caused by the intrusions and corrects earlier notions that the events are not linked trace element behaviour of zircon tb u and y content has been tracked through time in the samples and shows variations both within and between samples this heterogeneous behaviour at all scales appears to be common in metamorphic rocks and precludes the use of rules of thumb in the interpretation of zircon chemistry but chemical tracers are useful for recognition of zircon growth or recrystallization during metamorphism

seismic attenuation tomography using the frequency shift method we present a method for estimating seismic attenuation based on frequency shift data in most natural materials seismic attenuation increases with frequency the high frequency components of the seismic signal are attenuated more rapidly than the low frequency components as waves propagate as a result the centroid of the signal s spectrum experiences a downshift during propagation under the assumption of a frequency independent q model this downshift is proportional to a path integral through the attenuation distribution and can be used as observed data to reconstruct the attenuation distribution tomographically the frequency shift method is applicable in any seismic survey geometry where the signal bandwidth is broad enough and the attenuation is high enough to cause noticeable losses of high frequencies during propagation in comparison to some other methods of estimating attenuation our frequency shift method is relatively insensitive to geometric spreading reflection and transmission effects source and receiver coupling and radiation patterns and instrument responses tests of crosswell attenuation tomography on 1 d and 2 d geological structures are presented

complex seismic trace analysis of thin beds displays of complex trace attributes can help to define thin beds in seismic sections if the wavelet in a section is zero phase low impedance strata whose thicknesses are of the order of half the peak to peak period of the dominant seismic energy show up as anomalously high amplitude zones on instantaneous amplitude sections these anomalies result from the well known amplitude tuning effect which occurs when reflection coefficients of opposite polarity a half period apart are convolved with a seismic wavelet as the layers thin to a quarter period of the dominant seismic energy thinning is revealed by an anomalous increase in instantaneous frequency this behavior results from the less well known but equally important phenomenon of frequency tuning by beds which thin laterally instantaneous frequency reaches an anomalously high value when bed thickness is about a quarter period and remains high as the bed continues to thin in this paper complex trace analysis is applied to a synthetic model of a we

apatite dissolution into peraluminous haplogranitic melts an experimental study of solubilities and mechanisms apatite ap dissolution and solubility in the peraluminous haplogranite system were investigated in three sets of experiments at 750 c and 200 mpa ph2o as functions of ap grain size abundance melt ap ratio and melt asi alumina saturation index mol al2o3 na2o k2o cao between an asi of 1 1 1 metaluminous to mildly peraluminous the solubility of ap as measured by p2o5 in the melt is low 0 1 wt p2o5 which agrees with previous work in equilibrium runs with more strongly peraluminous compositions however ap solubility increases linearly with asi to p2o5 0 63 wt in melt at asi 1 3 and can be denned by a simple equation p2o5 3 4 3 1 asi r 0 833 which agrees within error with previous calculations reported in the literature in experiments where ap grains are sparce and widely separated i e simulating ap distribution in an ap bearing peraluminous protolith undergoing anatexis the dissolution of ap involves transient disequilibrium that promotes higher solubility of p2o5 up to nearly six times the equilibrium values adjacent to ap at a given bulk asi of melt and this increases the al si of melt in the ap dissolution aureole the approach to equilibrium between ap and melt is hastened by increasing the ap melt ratio within the local melt pool e g the capsule or by decreasing ap grain size for a similar melt ap ratio diffusivity calculations using inverse error function methods for the normal diffusion of p and ca yield dp 10 11 cm2 s and dca 10 10 cm2 s confirming prior results that diffusion of p away from ap surfaces is the rate limiting factor in ap dissolution these results combined with previous work at higher temperatures but on similar hydrous melts yield an activation energy e for p diffusion of 16 5 kcal mol and a frequency factor d0 of 1 4 10 3 cm2 s phosphorus diffusion through the melt is accompanied by uphill diffusion of al resulting in an increase of up to 2 wt al2o3 in melt near the ap within the ap dissolution aureole melt contains one additional al cation for every p cation i e al p 1 1 which is suggestive of an associated alpo4 complex the exchange reaction in melt is represented by alpsi 1 in which 2 to4 clusters are created in the place of 1 this exchange should be accompanied by discernable changes in melt properties e g density molar volume viscosity the results have applications to equilibrium and local disequilibrium effects during anatexis of apbearing metapelites and to the saturation limits of ap during crystallization of peraluminous magmas the dissolution of flux bearing minerals such as ap e g those containing p b or f may influence the stability and solubility of other trace element bearing minerals during anatexis of metapelites texture e g grain size and distribution and spacial relationship to other minerals plays an important role in reaction kinetics and at least temporarily in mineral solubilities the disequilibrium behavior of accessory minerals has critical consequences for ree modelling of granites

evolution of middle late triassic granitic intrusions from the badaguan cu mo deposit inner mongolia constraints from zircon u pb dating geochemistry and hf isotopes abstract the great xing an range in the eastern part of the central orogenic belt is one of the major polymetallic metallogenic belts in china the badaguan cu mo deposit in the erguna massif forms part of this belt and is a typical porphyry deposit associated with multiple granitic intrusions which are temporally and genetically related to the formation of this deposit in this paper we present new zircon u pb ages hf isotopic data and whole rock major and trace element geochemistry on the badaguan granitoids zircon u pb data indicate that the intrusions formed during two major phases ca 244 237 ma and ca 232 229 ma the middle triassic ca 244 237 ma phase is represented by a suite of medium k calc alkaline granite k feldspar granite biotite granite and porphyritic granite with i type affinities in general they are enriched in light rare earth elements lrees and large ion lithophile elements liles and depleted in heavy rare earth elements hrees and high field strength elements hfses their zircon ehf t values and two stage model ages tdm2 range from 1 5 to 8 5 with a mean value of 4 9 and from 732 to 1366 ma with a mean value of 959 ma respectively in contrast the late triassic ca 232 229 ma intrusions dominantly comprise a suite of high k calc alkaline i type granite porphyry and granodiorite porphyry these rocks are enriched in liles and lrees but depleted in hrees and hfses such as nb ta and ti their ehf t and tdm2 values range from 3 4 to 6 2 with a mean value of 5 0 and from 865 to 1047 ma with a mean value of 942 ma respectively these results suggest that the primary magmas of the middle and late triassic intrusive rocks were co magmatic and were mainly derived from the partial melting of juvenile thickened lower crust in addition the primary magma forming the middle triassic complex also assimilated a small amount of ancient crustal material and experienced a remarkable degree of fractional crystallization prior to its emplacement in contrast the source magma of the late triassic complex probably underwent interaction between of minor mantle derived melt and crustal components prior to emplacement the cu in badaguan deposit was likely sourced from the mantle derived melt whereas the mo was contributed by the host rocks with high mo contents

late jurassic early cretaceous closure of the mongol okhotsk ocean demonstrated by new mesozoic palaeomagnetic results from the trans baikal area se siberia summary we present new palaeomagnetic results from the transba ikal area se siberia from the mongol okhotsk suture zone the boundary between the amuria and siberia blocks in order to better constrain the time of closure of the mongol okhotsk ocean in the mesozoic we col lected 532 rock samples at 68 sites in six localities of basalts trachy basalts and andesites from both sides of the mongol okhotsk suture at unda river j 3 51 7 n 117 4 e kremljevka peak k1 51 8 n 117 5 e and torey lakes k 1 50 1 n 115 9 e on the southern side of the suture and at monostoy river j 1 51 1 n 106 8 e ingoda river k 1 51 2 n 112 2 e and bichura town k 1 50 6 n 107 6 e on the northern side progressive thermal demagnetization enabled us to resolve low ltc and high htc temperature components of magnetization at most sites jurassic palaeopoles computed from the htcs show a large discrepancy with respect to the apparent polar wander path of eurasia which we interpret in terms of 1700 2700 km of post late jurassic northward movement of amuria with respect to siberia although ge ological data suggest a middle jurassic closure of the mongol okhotsk ocean in the west trans baikal region our data give evidence of a large remaining palaeolatitude difference between the amuria and siberia blocks in contrast early cretaceous sites cluster remarkably well along a small circle which is centred on the average site location this implies the absence of post early cretaceous northward motion of amuria relative to siberia and demonstrates the pre early cretaceous closure of the mongol okhotsk ocean finally we interpret the very large tectonic rotations about local vertical axes evidenced by the small circle distribution of poles as arising both from collision processes and from left lateral shear movement along the suture zone due to the eastward extrusion of amuria under the effect of the collision of india into asia

velocity variations and water content estimated from multi offset ground penetrating radar the common midpoint cmp processing technique has been shown to be effective in improving the results of ground penetrating radar gpr profiling when radar data are collected with the cmp multioffset geometry stacking increases the signal to noise ratio of subsurface radar reflections and results in an improved subsurface image an important aspect of cmp processing is normal moveout velocity analysis our objectives are to show the effect of multiple velocity analyses on the stacked radar image and particularly to demonstrate that this velocity information can also be used to determine subsurface water content most gpr surveys are very limited in spatial extent and assume that within the survey range radar velocity structure in the shallow subsurface can be adequately approximated by a single velocity function in data processing in this study we show that variation in radar velocity can be quite significant and that the stacked profile improves as the number of velocity analysis locations is increased interval velocities can be calculated from the normal moveout velocities derived in the cmp velocity analysis with some reasonable assumptions about subsurface conditions necessary for radar propagation interval velocity can be converted to an estimate of volumetric water content therefore by collecting gpr data in the multioffset cmp geometry not only is the radar profile improved but it also allows for an interpretation of subsurface variation in water content we show the application of these techniques to multioffset gpr data from the chalk river test area operated by atomic energy of canada limited

frequency dependent attenuation analysis of ground penetrating radar data in the early 1990s it was established empirically that in many materials ground penetrating radar gpr attenuation is approximately linear with frequency over the bandwidth of a typical pulse further a frequency independent q parameter characterizes the slope of the band limited attenuation versus frequency curve here i derive the band limited q function from a first order taylor expansion of the attenuation coefficient this approach provides a basis for computing q from any arbitrary dielectric permittivity model for cole cole relaxation i find good correlation between the first order q approximation and q computed from linear fits to the attenuation coefficient curve over two octave bands the correlation holds over the primary relaxation frequency for some materials this relaxation occurs between 10 and 200 mhz a typical frequency range for many gpr applications frequency dependent losses caused by scattering and by the commonly overlooked problem of frequency dependent reflection

material contrast does not predict earthquake rupture propagation direction 1 earthquakes often occur on faults that juxtapose different rocks the result is rupture behavior that differs from that of an earthquake occurring on a fault in a homogeneous material previous 2d numerical simulations have studied simple cases of earthquake rupture propagation where there is a material contrast across a fault and have come to two different conclusions 1 earthquake rupture propagation direction can be predicted from the material contrast and 2 earthquake rupture propagation direction cannot be predicted from the material contrast in this paper we provide observational evidence from 70 years of earthquakes at parkfield ca and new 3d numerical simulations both the observations and the numerical simulations demonstrate that earthquake rupture propagation direction is unlikely to be predictable on the basis of a material contrast

carboniferous granitic plutons from the northern margin of the north china block implications for a late palaeozoic active continental margin we report four late palaeozoic zircon sensitive high resolution ion microprobe shrimp u pb ages for granitic plutons from the inner mongolia palaeo uplift on the northern margin of the north china block these cast a new light on the poorly understood tectonic history of the northern margin of the north china block and the central asian orogenic belt during the late palaeozoic the plutons have for a long time been considered to belong to the early precambrian basement of the north china block our new shrimp u pb zircon dating of four plutons at longhua daguangding boluonuo and hushiha has yielded intrusive ages of 311 2 ma 324 6 ma 302 4 ma and 310 5 ma respectively geochemical data suggest that these granitoids have a calc alkaline subduction related i type signature indicating the existence of an andean style continental arc along the northern margin of the north china block during the late palaeozoic our results also indicate that the palaeo asian ocean still existed during latest carboniferous earliest permian time and that the final collision between the southern mongolia composite terranes and the north china block occurred later than c 290 ma we suggest that the northern margin of the north china block was an active continental margin and the inner mongolia palaeo uplift is a deeply exhumed mid crustal root of a late palaeozoic andean style continental arc

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

modelling of gpr waves for lossy media obeying a complex power law of frequency for dielectric permittivity the attenuation of ground penetrating radar gpr energy in the subsurface decreases and shifts the amplitude spectrum of the radar pulse to lower frequencies absorption with increasing traveltime and causes also a distortion of wavelet phase dispersion the attenuation is often expressed by the quality factor q for gpr studies q can be estimated from the ratio of the real part to the imaginary part of the dielectric permittivity we consider a complex power function of frequency for the dielectric permittivity and show that this dielectric response corresponds to a frequency independent q or simply a constant q model the phase velocity dispersion relationship and the absorption coefficient of electromagnetic waves also obey a frequency power law this approach is easy to use in the frequency domain and the wave propagation can be described by two parameters only for example q and the phase velocity at an arbitrary reference frequency this simplicity makes it practical for any inversion technique furthermore by using the hilbert transform relating the velocity and the absorption coefficient which obeys a frequency power law we find the same dispersion relationship for the phase velocity both approaches are valid for a constant value of q over a restricted frequency bandwidth and are applicable in a material that is assumed to have no instantaneous dielectric response many gpr profiles acquired in a dry aeolian environment have shown a strong reflectivity inside dunes changes in water content are believed to be the origin of this reflectivity we model the radar reflections from the bottom of a dry aeolian dune using the 1d wavelet modelling method we discuss the choice of the reference wavelet in this modelling approach a trial and error match of modelled and observed data was performed to estimate the optimum set of parameters characterizing the materials composing the site additionally by combining the complex refractive index method crim and or topp equations for the bulk permittivity dielectric constant of moist sandy soils with a frequency power law for the dielectric response we introduce them into the expression for the reflection coefficient using this method we can estimate the water content and explain its effect on the reflection coefficient and on wavelet modelling

applying reflection tomography in the postmigration domain to multifold ground penetrating radar data acquisition and processing of multifold ground penetrating radar gpr data enable detailed measurements of lateral velocity variability the velocities constrain interpretation of subsurface materials and lead to significant improvement in image accuracy when coupled with prestack depth migration psdm reflection tomography in the postmigration domain was introduced in the early 1990s for velocity estimation in seismic reflection this robust accurate method is directly applicable in multifold gpr imaging at a contaminated waste facility within the u s department of energy s hanford site in washington the method is used to identify significant lateral and vertical velocity heterogeneity associated with infilled waste pits using both the psdm images and velocity models in interpretation a paleochannel system that underlies the site and likely forms contaminant migration pathways is identified

estimating porosity with ground penetrating radar reflection tomography a controlled 3 d experiment at the boise hydrogeophysical research site 1 to evaluate the uncertainty of water saturated sediment velocity and porosity estimates derived from surface based ground penetrating radar reflection tomography we conducted a controlled field experiment at the boise hydrogeophysical research site bhrs the bhrs is an experimental well field located near boise idaho the experimental data set consisted of 3 d multioffset radar acquired on an orthogonal 20 30 m surface grid that encompassed a set of 13 boreholes experimental control included 1 1 d vertical velocity functions determined from traveltime inversion of vertical radar profiles vrp and 2 neutron porosity logs we estimated the porosity distribution in the saturated zone using both the topp and complex refractive index method crim equations and found the crim estimates in better agreement with the neutron logs we found that when averaged over the length of the borehole surface derived velocity measurements were within 5 of the vrp velocities and that the porosity differed from the neutron log by less than 0 05 the uncertainty however is scale dependent we found that the standard deviation of differences between ground penetrating radar derived and neutron log derived porosity values was as high as 0 06 at an averaging length of 0 25 m but decreased to less than 0 02 at length scale of 11 m additionally we used the 3 d porosity distribution to identify a relatively high porosity anomaly i e local sedimentary body within a lower porosity unit and verified the presence of the anomaly using the neutron porosity logs since the reflection tomography approach requires only surface data it can provide rapid assessment of bulk hydrologic properties identify meter scale anomalies of hydrologic significance and may provide input for other higher resolution measurement methods

permian geodynamic setting of northeast china and adjacent regions closure of the paleo asian ocean and subduction of the paleo pacific plate abstract northeast china and adjacent regions are located in the central east asian continent and consist tectonically of both the paleo asian and paleo pacific orogens between the siberian platform and sino korean north china block this paper discusses some hotly debated issues concerning the permian geodynamic setting of these regions based on a comprehensive analysis of available geological geochemical paleobiogeographical and paleomagnetic data spatial and temporal distribution of ophiolites and associated continental marginal sequences permian sedimentary sequences spatial distribution and geochemistry of permian magmatic rocks and the evolution of paleobiogeographical realms imply 1 that the permian marine basins in northeast china and adjacent regions include remnants of the paleo asian ocean in southeastern inner mongolia and central jilin province and active continental margins of the paleo pacific ocean 2 that the suture between the siberian and sino korean paleoplates was finally emplaced in the permian and is located in areas from suolunshan solonker eastwards through regions north to the xar moron river in southeastern inner mongolia and then central jilin province to the yanji area and 3 that the permian crustal evolution of northeast china and adjacent regions as well as parts of the siberian paleoplate was influenced by subduction of the paleo pacific oceanic plate finally the permian tectonic framework and paleogeography of northeast china and adjacent regions in central east asia are discussed briefly and early and late permian palinspastic reconstruction maps are provided

spatial temporal relationships of mesozoic volcanic rocks in ne china constraints on tectonic overprinting and transformations between multiple tectonic regimes abstract la icp ms zircon u pb ages and geochemical data are presented for the mesozoic volcanic rocks in northeast china with the aim of determining the tectonic settings of the volcanism and constraining the timing of the overprinting and transformations between the paleo asian ocean mongol okhotsk and circum pacific tectonic regimes the new ages together with other available age data from the literature indicate that mesozoic volcanism in ne china can be subdivided into six episodes late triassic 228 201 ma early middle jurassic 190 173 ma middle late jurassic 166 155 ma early early cretaceous 145 138 ma late early cretaceous 133 106 ma and late cretaceous 97 88 ma the late triassic volcanic rocks occur in the lesser xing an zhangguangcai ranges where the volcanic rocks are bimodal and in the eastern heilongjiang jilin provinces where the volcanics are a type rhyolites implying that they formed in an extensional environment after the final closure of the paleo asian ocean the early middle jurassic 190 173 ma volcanic rocks both in the erguna massif and the eastern heilongjiang jilin provinces belong chemically to the calc alkaline series implying an active continental margin setting the volcanics in the erguna massif are related to the subduction of the mongol okhotsk oceanic plate beneath the massif and those in the eastern jilin heilongjiang provinces are related to the subduction of the paleo pacific plate beneath the eurasian continent the coeval bimodal volcanic rocks in the lesser xing an zhangguangcai ranges were probably formed under an extensional environment similar to a backarc setting of double direction subduction volcanic rocks of middle late jurassic 155 166 ma and early early cretaceous 145 138 ma age only occur in the great xing an range and the northern hebei and western liaoning provinces limited to the west of the songliao basin and they belong chemically to high k calc alkaline series and a type rhyolites respectively combined with the regional unconformity and thrust structures in the northern hebei and western liaoning provinces we conclude that these volcanics formed during a collapse or delamination of a thickened continental crust related to the evolution of the mongol okhotsk suture belt the late early cretaceous volcanic rocks widely distributed in ne china belong chemically to a low to medium k calc alkaline series in the eastern heilongjiang jilin provinces i e the eurasian continental margin and to a bimodal volcanic rock association within both the songliao basin and the great xing an range the volcanics in the eastern heilongjiang jilin provinces formed in an active continental margin setting related to the subduction of the paleo pacific plate beneath the eurasian continent and the bimodal volcanics formed under an extensional environment related either to a backarc setting or to delamination of a thickened crust or both late cretaceous volcanics limited to the eastern heilongjiang jilin provinces and the eastern north china craton ncc consist of calc alkaline rocks in the eastern heilongjiang jilin provinces and alkaline basalts in the eastern ncc suggesting that the former originated during subduction of the paleo pacific plate beneath the eurasian continent whereas the latter formed in an extensional environment similar to a backarc setting taking all this into account we conclude that 1 the transformation from the paleo asian ocean regime to the circum pacific tectonic regime happened during the late triassic to early jurassic 2 the effect of the mongol okhotsk suture belt on ne china was mainly in the early jurassic middle late jurassic and early early cretaceous and 3 the late early cretaceous and late cretaceous volcanics can be attributed to the subduction of the paleo pacific plate beneath the eurasian continent

an eulerian equation for snow accumulation downstream of an object this study investigated the form of the governing equation for the particle distribution by focusing on the particle motion processes rather than flow regime and particle characteristics a linear erosion term for a fetch eddy effect was introduced to the advection dispersion equation the equation formulated in this paper described most of the particle deposit patterns behind an object including porous and solid snow fences and a tree this theory may enable us to estimate particle motion parameters such as diffusion drift and erosion coefficients from field observed particle distributions snow stratigraphy observed by ground penetrating radar gpr was used verify to result of the modeled theoretical snow redistribution these analyses confirmed the effectiveness of the linear erosion term at explaining the particle deposition patterns due to eddys around a porous snow fence this article is protected by copyright all rights reserved

estimating alpine snowpack properties using fmcw radar large variations in both snow water equivalent swe and snow slope stability are known to exist in the alpine snowpack caused by wind topographic and microclimatic effects this variability makes extrapolation of point measurements of snowpack properties difficult and prone to error but these types of measurements are used to estimate swe and stability across entire mountain ranges radar technology provides a promising alternative to point measurements because large areas can be covered quickly and non intrusively there is great potential for obtaining information on a large spatial scale from airborne applications frequency modulated continuous wave fmcw radar measurements were made from the ground in several different alpine snowpacks along with manual and in situ electrical measurements the surface and ground reflections from the radar data combined with an average density estimate can provide a useful estimate of swe in addition the locations of internal reflections are highly correlated with both visually identified layers and measured changes in in situ dielectric properties

a type granites in northeastern china age and geochemical constraints on their petrogenesis abstract a type granites are widely distributed in northeastern china ne china they were emplaced during three major episodes the permian late triassic to early jurassic and early cretaceous and evolved in different tectonic regimes according to their mineralogical and geochemical characteristics two subgroups of a type granites aluminous and peralkaline can be recognized the peralkaline subgroup contains alkali mafic minerals such as riebeckite arfvedsonite and sodic pyroxene while the aluminous subgroup contains annite and fe rich calcic or sodic calcic amphibole with respect to the aluminous subgroup the peralkaline granites contain higher rb ga and total rare earth elements ree but lower mgo cao al 2 o 3 ba and sr based on the discrimination criteria of eby geology 20 1992 641 the permian and late triassic to early jurassic a type granites belong to the a 2 post orogenic type whereas the early cretaceous granites are of the a 1 anorogenic type nd isotopic compositions of these a type granites indicate their derivation from a dominantly juvenile crustal source their origin is thought to have involved partial melting of an underplated lower crustal source because the generation of a type granites requires high melting temperature we propose models involving slab break off lithospheric delamination and extension the permian a type granites have the same age range as those in eastern junggar southern mongolia and central inner mongolia they occur along a major suture and form a narrow belt between the north china and siberian cratons we suggest that their formation was associated with post collisional slab break off the late triassic to early jurassic a type granites are likely to be the product of lithospheric delamination after the final collision of the major crustal blocks in the late paleozoic to early triassic the early cretaceous a type granites have an anorogenic affinity and were possibly associated with rifting in eastern china at this time associated with the onset of paleo pacific subduction consequently we conclude that the a type granites in ne china were generated at three different times involving multiple processes operative in different tectonic environments

spatial extent and temporal variability of greenland firn aquifers detected by ground and airborne radars we document the existence of widespread firn aquifers in an elevation range of 1200 2000 m in the high snow accumulation regions of the greenland ice sheet we use nasa operation icebridge accumulation radar data from five campaigns 2010 2014 to estimate a firn aquifer total extent of 21 900 km2 we investigate two locations in southeast greenland where repeated radar profiles allow mapping of aquifer extent and water table variations in the upper part of helheim glacier the water table rises in spring following above average summer melt showing the direct firn aquifer response to surface meltwater production changes after spring 2012 a drainage of the firn aquifer lower margin 5 km is inferred from both 750 mhz accumulation radar and 195 mhz multicoherent radar depth sounder data for 2011 2014 we use a ground penetrating radar profile located at our ridgeline field site and find a spatially stable aquifer with a water table fluctuating less than 2 5 m vertically when combining radar data with surface topography we find that the upper elevation edge of firn aquifers is located directly downstream of locally high surface slopes using a steady state 2 d groundwater flow model water is simulated to flow laterally in an unconfined aquifer topographically driven by ice sheet surface undulations until the water encounters crevasses simulations suggest that local flow cells form within the helheim aquifer allowing water to discharge in the firn at the steep to flat transitions of surface topography supported by visible imagery we infer that water drains into crevasses but its volume and rate remain unconstrained

geophysical investigation of underground water content zones using electrical resistivity tomography and ground penetrating radar a case study in hesarak karaj iran abstract this paper describes the successful application of an integrated geophysical survey to investigate the depth of underground water table and the location of probable cavity occurrences at a developing residential area to design the foundation of under constructing urban buildings located at hesarak karaj alborz province of iran the integrated shallow and non invasive geophysical survey consists of electrical resistivity tomography ert and ground penetrating radar gpr these methods could appropriately indicate the existence of the water table at a depth of approximately 12 m while processed gpr radargrams localized no cavity occurrences in the studied site a 100 mhz shielded gpr antenna has been used to conduct a high resolution shallow subsurface survey in order to delineate probable cavities of the area and two electrical arrays of gradient and wenner have been used as well to image resistivity variations of subsurface layers especially for prospecting water saturated zone the acquired results which were in good accordance with the reality of the studied area at locating water table and cavity occurrences could effectively provide guidance to builders in order to tackle water flow issue and not to concern about filling cavities during constructing any building in the site

continuous snowpack monitoring using upward looking ground penetrating radar technology snow stratigraphy and water percolation are key contributing factors to avalanche formation so far only destructive methods can provide this kind of information radar technology allows continuous non destructive scanning of the snowpack so that the temporal evolution of internal properties can be followed we installed an upward looking ground penetrating radar system upgpr at the weissfluhjoch study site davos switzerland during two winter seasons 2010 11 and 2011 12 we recorded data with the aim of quantitatively determining snowpack properties and their temporal evolution we automatically derived the snow height with an accuracy of about 5 cm tracked the settlement of internal layers 7 cm and measured the amount of new snow 10 cm using external snow height measurements we determined the bulk density with a mean error of 4 3 compared to manual measurements radar derived snow water equivalent deviated from manual measurements by 5 furthermore we tracked the location of the dry to wet transition in the snowpack until water percolated to the ground based on the transition and an independent snow height measurement it was possible to estimate the volumetric liquid water content and its temporal evolution even though we need additional information to derive some of the snow properties our results show that it is possible to quantitatively derive snow properties with upgpr