study of the effect of 17 18 march 2015 geomagnetic storm on the indian longitudes using gps and c nofs the largest geomagnetic storm in solar cycle 24 occurred during march 17 18 2015 where the main phase of the storm commenced from 07 00 ut of march 17 2015 and reached the dst negative minimum at 22 00 ut the present paper reports observations of tec amplitude and phase scintillations from different gps stations of india during the storm of march 17 and highlights its effects on gps it also presents the global esf occurrence during the storm using total ion density drift measurements from c nofs satellite tec enhancements were noted from stations along 77oe meridian around 10 00 ut on march 17 compared to march 16 and 18 indicating positive storm effects arising out of equatorward neutral wind in the local morning noon sector of the main phase intense scintillation observations from calcutta were most extensive during 15 00 16 00 ut march 17 and the receiver recorded a longitude deviation of 5 2 m during this time cycle slips of the order of 8 s could be observed during periods of intense phase scintillations on the same night intense scintillation observation from palampur is an exceptional phenomenon attributed to the dramatic enhancement of the electric field due to ppef leading to a very high upward ion velocity over the magnetic equator as recorded by c nofs the total ion density measured globally by c nofs reveals two distinct longitude regions of esf occurrence during the storm i east pacific sector and ii indian longitude during the storm the time and longitude of esf occurrence could be predicted using the time of southward turning of imf bz

low latitude ionospheric d region dependence on solar zenith angle phase and amplitude measurements of vlf radio signals on a short nearly all sea path between two hawaiian islands are used to find the height and sharpness of the lower edge of the daytime tropical d region as a function of solar zenith angle sza the path used was from u s navy transmitter npm 21 4 khz on oahu to keauhou 306 km away on the west coast of the big island of hawaii where ionospheric sensitivity was high due to the destructive interference between the ionospherically reflected wave and the ground wave particularly around the middle of the day the height and sharpness are thus found to vary from h 69 3 0 3km and 0 49 0 02 km 1 for sza 10 at midday to h 80 km and 0 30 km 1 as the sza approached 70 90 near dawn and dusk for this tropical path additional values for the variations of h and with solar zenith angle are also found from vlf phase and amplitude observations on other similar paths the short path nwc to karratha in nw australia and the long paths nwc to kyoto in japan and nau puerto rico to st john s canada significant differences in the sza variations of h and were found between low and middle latitudes resulting from the latitudinally varying interplay between lyman and galactic cosmic rays in forming the lower d region both latitude ranges showed 0 30 km 1 during sunrise sunset conditions 1

ground penetrating radar assisted saturation and permeability estimation in bimodal systems near surface investigations often require characterization of vadose zone hydraulic parameters conventional sampling or borehole techniques for estimating these parameters are costly time consuming and invasive all of which limit collection of hydrogeological data at a spacing needed for detailed site characterization incorporation of two or three dimensional densely sampled geophysical data with conventional hydrological data increases the amount of data available for the characterization and thus has the potential to significantly improve the hydraulic parameter estimates over those obtained from borehole data alone the hydraulic estimation procedure can be greatly improved by incorporating dielectric information potentially available from ground penetrating radar gpr a noninvasive high resolution geophysical method the procedures for collecting and processing gpr data in the format needed for the proposed estimation technique are relatively new and still a topic of research our method requires as a starting point the ability to estimate dielectric constants from gpr data numerical experiments were performed to investigate the general utility of the gpr assisted estimation technique under a range of conditions three bimodal systems were investigated each system being composed of a sand facies together with another facies with a larger clay volume fraction each facies was defined using characteristic values of clay content porosity and permeability using dielectric information and petrophysical relations degree of saturation and intrinsic permeability values at each location within the three systems were identified for bimodal systems a dielectric constant measurement corresponds to two possible values of saturation and intrinsic permeability at each location single values of saturation and intrinsic permeability were estimated from these values using the principle of maximum likelihood results from case studies demonstrate that a combination of gpr data with conventional borehole data significantly improves the estimates of saturation and has the potential to improve the estimates of permeability over those obtained from well bore data alone the proposed method should be especially advantageous for vadose zone characterization in areas favorable for gpr data acquisition where detailed hydraulic parameter information is required but the drilling of numerous boreholes is prohibited

effects of st patrick s day geomagnetic storm of march 2015 and of june 2015 on low equatorial d region ionosphere d region effects of the 17 19 march 2015 a st patrick s day super geomagnetic storm dst 223 nt using a navigational transmitter very low frequency vlf signal nwc 19 8 khz recorded at a low latitude indian station allahabad geomag lat 16 45 n have been analyzed and compared with similar strength of the 22 25 june 2015 storm dst 204 nt during the march storm nwc signal amplitude decreased on 17 march main phase of the storm and recovered on 27 march which is 1 day after the recovery of the storm whereas for the june storm vlf amplitude decreased for 2 days only during its recovery phase the decrease in the amplitude was pronounced during evening terminator for both the storms the modeling of vlf signal anomaly on 17 march and on 25 june using long wave propagation capability code shows an increase in the d region reference height h by 2 6 km and 2 5 km for march and june storms respectively the d region electron density ne determined using storm time h and sharpness factor shows a decrease in the ne during the main phase followed by a slow recovery during the recovery phase of the march storm whereas june 2015 storm showed a decrease in the ne only on 25 and 26 june morlet wavelet analysis of the amplitude for both the storms shows a presence of strong wave like signatures suggesting propagation of atmospheric gravity waves traveling ionosphere disturbances to the low latitude d region due to the joule heating at high latitudes

integrated method of rs and gpr for monitoring the changes in the soil moisture and groundwater environment due to underground coal mining mining affects the environment in different ways depending on the physical context in which the mining occurs in mining areas with an arid environment mining affects plants growth by changing the amount of available water this paper discusses the effects of mining on two important determinants of plant growth soil moisture and groundwater table gwt which were investigated using an integrated approach involving a field sampling investigation with remote sensing rs and ground penetrating radar gpr to calculate and map the distribution of soil moisture for a target area we initially analyzed four models for regression analysis between soil moisture and apparent thermal inertia and finally selected a linear model for modeling the soil moisture at a depth 10 cm the relative error of the modeled soil moisture was about 6 3 and correlation coefficient 0 7794 a comparison of mined and unmined areas based on the results of limited field sampling tests or rs monitoring of landsat 5 thermatic mapping tm data indicated that soil moisture did not undergo remarkable changes following mining this result indicates that mining does not have an effect on soil moisture in the shendong coal mining area the coverage of vegetation in 2005 was compared with that in 1995 by means of the normalized difference vegetation index ndvi deduced from tm data and the results showed that the coverage of vegetation in shendong coal mining area has improved greatly since 1995 because of policy input rmb 0 4 per ton coal production by shendong coal mining company the factor most affected by coal mining was gwt which dropped from a depth of 35 41 m before mining to a depth of 43 38 m after mining at the bulianta coal mine based on water well measurements ground penetrating radar at frequencies of 25 and 50 mhz revealed that the deepest gwt was at about 43 4 m there was a weak water linkage between the unsaturated zone and groundwater and the decline of water table primarily resulted from the well pumping for mining safety rather than the movement of cracking strata this result is in agreement with the measurements of the water wells the roots of nine typical plants in the study area were investigated populus was found to have the deepest root system with a depth of about 26 m based on an assessment of plant growth demands and the effect of mining on environmental factors we concluded that mining will have less of an effect on plant growth at those sites where the primary gwt depth before mining was deep enough to be unavailable to plants if the primary gwt was available for plant growth before mining especially to those plants with deeper roots mining will have a significant effect on the growth of plants and the mechanism of this effect will include the loss of water to roots and damage to the root system

middle and low latitude ionosphere response to 2015 st patrick s day geomagnetic storm this paper presents a study of the st patrick s day storm of 2015 with its ionospheric response at middle and low latitudes the effects of the storm in each longitudinal sector asian african american and pacific are characterized using global and regional electron content at the beginning of the storm one or two ionospheric positive storm effects are observed depending on the longitudinal zones after the main phase of the storm a strong decrease in ionization is observed at all longitudes lasting several days the american region exhibits the most remarkable increase in vertical total electron content vtec while in the asian sector the largest decrease in vtec is observed at low latitudes using spectral analysis we were able to separate the effects of the prompt penetration of the magnetospheric convection electric field ppef and of the disturbance dynamo electric field ddef on the basis of ground magnetic data concerning the ppef earth s magnetic field oscillations occur simultaneously in the asian african and american sectors during southward magnetization of the b z component of the interplanetary magnetic field concerning the ddef diurnal magnetic oscillations in the horizontal component h of the earth s magnetic field exhibit a behavior that is opposed to the regular one these diurnal oscillations are recognized to last several days in all longitudinal sectors the observational data obtained by all sensors used in the present paper can be interpreted on the basis of existing theoretical models

high resolution water content estimation from surface based ground penetrating radar reflection data by impedance inversion 1 mapping hydrological parameter distributions in high resolution is essential to understand and simulate groundwater flow and contaminant transport of particular interest is surface based ground penetrating radar gpr reflection imaging in electrically resistive sediments because of the expected close link between the subsurface water content and the dielectric permittivity which controls gpr wave velocity and reflectivity conventional tools like common midpoint cmp velocity analysis provide physical parameter models of limited resolution only we present a novel reflection amplitude inversion workflow for surface based gpr data capable of resolving the subsurface dielectric permittivity and related water content distribution with markedly improved resolution our scheme is an adaptation of a seismic reflection impedance inversion scheme to surface based gpr data key is relative amplitude preserving data preconditioning including gpr deconvolution which results in traces with the source wavelet distortions and propagation effects largely removed the subsequent inversion for the underlying dielectric permittivity and water content structure is constrained by in situ dielectric permittivity data obtained by direct push logging after demonstrating the potential of our novel scheme on a realistic synthetic data set we apply it to two 2 d 100 mhz gpr profiles acquired over a shallow sedimentary aquifer resulting in water content images of the shallow 3 7 m depth saturated zone having decimeter resolution

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

duskside enhancement of equatorial zonal electric field response to convection electric fields during the st patrick s day storm on 17 march 2015 the equatorial zonal electric field responses to prompt penetration of eastward convection electric fields ppef were compared at closely spaced longitudinal intervals at dusk to premidnight sectors during the intense geomagnetic storm of 17 march 2015 at dusk sector indian longitudes a rapid uplift of equatorial f layer to 550 km and development of intense equatorial plasma bubbles epbs were observed these epbs were found to extend up to 27 13 n and 25 98 s magnetic dip latitudes indicating their altitude development to 1670 km at apex in contrast at few degrees east in the premidnight sector thailand indonesian longitudes no significant height rise and or epb activity has been observed the eastward electric field perturbations due to ppef are greatly dominated at dusk sector despite the existence of background westward ionospheric disturbance dynamo idd fields whereas they were mostly counter balanced by the idd fields in the premidnight sector in situ observations from swarm a and swarm c and communication navigation outage forecasting system satellites detected a large plasma density depletion near indian equatorial region due to large electrodynamic uplift of f layer to higher than satellite altitudes further this large uplift is found to confine to a narrow longitudinal sector centered on sunset terminator this study brings out the significantly enhanced equatorial zonal electric field in response to ppef that is uniquely confined to dusk sector the responsible mechanisms are discussed in terms of unique electrodynamic conditions prevailing at dusk sector in the presence of convection electric fields associated with the onset of a substorm under southward interplanetary magnetic field bz

improving groundwater project analysis with geophysical data when interpreting the earth s subsurface for groundwater contamination we face a fundamental problem we typically sample one millionth of the relevant material if only these data are used to determine the material between boreholes and the continuity of high hydraulic conductivity units the answers will be ambiguous for example consider a site where three boreholes intersect two hydrofacies figure 1 if no other information is available all of the interpretations shown and many more not shown are equally likely

three dimensional reverse time migration of ground penetrating radar signals three dimensional 3d ground penetrating radar gpr systems and 3d seismic imaging techniques have been developing fast and evolving rapidly in the last decade ray based migration methods have been successfully applied to processing 3d gpr signals based on the similarity between electromagnetic and seismic waves however reverse time migration rtm of 3d gpr signals has not been well studied in the past in this paper we present a 3d rtm based on maxwell s equations for 3d gpr surveys migration recovers the true subsurface structure from a distorted and unfocused time profile and suppresses common electromagnetic clutter and noise rtm based on maxwell s equations can consider conductivity directly and compensate for the attenuation within a high conductivity zone compared with 2d rtm 3d rtm back propagates both in line and cross line signals simultaneously and can include complex 3d permittivity and conductivity models we have integrated a parallel finite difference time domain fdtd algorithm based on a hybrid mpi and openmp scheme to reduce the computational cost of 3d problems the 3d rtm experiments on an anomaly of em shape and a realistic sand dune model demonstrate the effective recovery of 3d subsurface structures

investigating the geoelectrical response of hydrocarbon contamination undergoing biodegradation 1 a newly proposed geoelectrical model for hydrocarbon contaminated sites predicts high conductivities coincident with the contaminated zone as opposed to the traditionally accepted low conductivity the model attributes the high conductivities to mineral weathering resulting from byproducts of microbial redox processes to evaluate this conductive model in situ vertical conductivity measurements were acquired from a light non aqueous phase liquid lnapl contaminated site the results showed high conductivities coincident with the zone of contamination and within the smear zone influenced by seasonal water table fluctuations we infer this zone as an active zone of biodegradation and suggest significant microbial degradation under partially water saturated conditions a simple archie s law analysis shows large pore water conductivities necessary to reproduce the bulk conductivity measured at the contaminated location this study supports the conductive layer model and demonstrates the potential of geoelectrical investigations for assessing microbial degradation of lnapl impacted soils

an fe analogue of kinoshitalite from the broken hill massive sulfide deposit in the namaqualand metamorphic complex south africa micas with variable ba content in the interlayer sites occur in silicate rich bands within the high grade metamorphic banded iron formation enclosing massive sulfide bodies in the broken hill deposit namaqualand metamorphic complex south africa in those layers that contain neither potassium feldspar nor muscovite a green barian up to 17 wt o bao trioctahedral mica occurs that is similar to kinoshitalite in contrast to the originally described kinoshitalite however this mica is fe rich average xfe 0 65 suggesting the existence of an fe analogue of kinoshitalite not described to date ion chromatographic analysis indicates that about 8 1oof the total fe in this mica is present as fe3 and a typical formula is ba1 2k0 4 fel1 mno 2mg2 oalo 2fe6 t tio 2 ai3 osi5 o 02o oh l sf2 2 the unit cell parameters were determined as follows a 5 383 2 b 9 328 8 c 10 055 8 a j 100 44 5 0 with v 496 5 a3 and z 2 the space group is c21m the ba rich mica formed at the peak of metamorphism t 670 t 20 c p 4 5 t 1 0 kbar at a ph below the muscovite potassium feldspar buffer 102buffered by quartz fayalite magnetite and fs2between 10 5 and 10 7

spectral induced polarization signatures of abiotic fes precipitation in recent years geophysical methods have been shown to be sensitive to microbial induced mineralization processes the spectral induced polarization sip method appears to be very promising for monitoring mineralization and microbial processes with this work we study the links of mineralization and sip signals in the absence of microbial activity we recorded the sip response during abiotic fes precipitation we show that the sip signals are diagnostic of fes mineralization and can be differentiated from sip signals from biomineralization processes more specifically the imaginary conductivity shows almost linear dependence on the amount of fes precipitating out of solution above the threshold value 0 006 gr under our experimental conditions this research has direct implications for the use of the sip method as a monitoring and decision making tool for sustainable remediation of metals in contaminated soils and groundwater

temporal geophysical signatures from contaminant mass remediation we have previously documented changes in bulk electrical conductivity self potential sp and ground penetrating radar gpr reflections in a field setting caused by biogeochemical transformations of hydrocarbon contaminated media these transformations are associated with hydrocarbon biodegradation the results of surface geophysical surveys acquired in 1996 2003 and 2007 document changes in geophysical signatures associated with removing hydrocarbon mass in the contaminated zone initial investigations in 1996 showed that relative to background the contaminated area was characterized by higher bulk electrical conductivity positive sp anomaly and attenuated gpr reflections repeated surveys in 2003 and 2007 over the contaminated area showed that in 2007 the bulk electrical conductivityhad reverted to near background conditions the positive sp anomaly became more negative and the zone of attenuated gpr reflections showed increased signal strength removal of hydrocarbon mass in the vadose zone o

structural evolution of the northern end of the oman ophiolite and enclosed granulites abstract a combined structural field mapping microstructural and petrographic study has been undertaken to better understand the origin and evolution of the northernmost part of the oman ophiolite khawr fakkan massif in the framework of an oceanic spreading centre emplacement of a sheet of granulite facies metamorphic rocks into the peridotites occurred at temperatures at which the peridotites deformed ductily the metamorphic rocks define the southern extension of a block boundary which separates an eastern peridotite part displaying high temperature fabrics from a western one with porphyroclastic to mylonitic fabrics granitoid intrusions representing partial melts from the metamorphic rocks occur only in the ophiolitic part overlying the metamorphic rocks thus delineating the same boundary between the two mantle blocks this high temperature boundary is not visible on satellite or aerial photographs the granulite facies foliations and lineations in the metamorphic rocks can be correlated with porphyroclastic textures developed at decreasing temperatures in the associated peridotites and to the obduction of the ophiolite the final emplacement of the metamorphic rocks in their present position was accompanied by retrograde hydration decompression and continuous deformation at temperatures ranging from 800 to 300 c the hydration is extended along the wadi ham fault two models are proposed for the emplacement of the metamorphic rocks in the first model the protolith of the metamorphic rocks was deposited in a pull apart basin along a transform fault and then subducted along the transform fault after reversal from transtension to transpression in this model the ophiolite obduction occurred later along another thrust plane in the second model the protolith material descends along an intraoceanic subduction zone and is emplaced into the ophiolite hanging wall along a secondary thrust caused by transpressive or rotational movements during the ophiolite obduction in this case the ophiolite obduction occurred along the same intraoceanic subduction plane

response of the low latitude d region ionosphere to extreme space weather event of 14 16 december 2006 the response of the d region low latitude ionosphere has been examined for extreme space weather event of 14 16 december 2006 associated with a x1 5 solar flare and an intense geomagnetic storm dst 146 nt using vlf signals from northwest cape australia nwc 19 8 khz and lualualei hawaii callsign npm 21 4 khz transmitters monitored at suva geographic coordinates 18 10 s 178 40 e fiji modeling of flare associated amplitude and phase enhancements of nwc 3 6 db 223 and npm 5 db 153 using long wave propagation capability code shows reduction in the d region reflection height h by 11 1 km and 9 4 km and enhancement in ionization gradients described by increases in the exponential sharpness factor by 0 122 and 0 126 km 1 for the nwc and npm paths respectively during the storm the daytime signal strengths of the nwc and npm signals were reduced by 3 2 db on 15 and 16 december for about 46 h and recovered by 17 december modeling for the nwc path shows that storm time values of h and were reduced by 1 2 km and 0 06 km 1 respectively morlet wavelet analysis of signal amplitudes shows no clearly strong signatures of gravity wave propagation to low latitudes during the main and recovery phases the reduction in vlf signal strength is due to increased signal attenuation and absorption by the earth ionosphere waveguide due to storm induced d region ionization changes and hence changes in d region parameters the long duration of the storm effect results from the slow diffusion of changed composition ionization at d region altitudes compared with higher altitudes in the ionosphere

ionospheric d region parameters obtained using vlf measurements in the south pacific region the diurnal variations in the phase and amplitude of nwc npm and nlk very low frequency vlf transmissions received at suva fiji have been modeled using the long wave propagation capability lwpc v2 1 code to determine the ionospheric d region parameters h reference height and rate of increase of electron density with height for different daytime and nighttime conditions along the transmitter receiver great circle paths trgcps measured vlf signal amplitude and phase show explicit variation over the day and nighttime along the trgcp also revealing amplitude minima and phase steps during sunrise and sunset as the day night terminator traverses the trgcp while the daytime signal strength is reasonably smooth at nighttime the signal exhibits a great deal of variability for three signal paths the mean daytime h and were found to be 70 7 km and 0 40 km 1 respectively while nighttime mean values of these parameters were found to be 84 2 km and 0 68 km 1 respectively the temporal and day to day variability of the nighttime d region parameters shows that h and ranges in between 83 0 85 0 km and 0 58 0 80 km 1 respectively one of the possible sources of nighttime signal variability is increase in the number of modes propagating and relative complex interference between them along the trgcps whereby the weaker modes also become significant at night due to reduced attenuation in addition the variations in the nighttime d region itself may be a cause of high signal variability

rock water interaction in dielectric properties experiments with hydrophobic sandstones the dielectric constant of a partially saturated sandstone varies as a function of the level of water saturation experimental data indicate that rock water interaction at low saturations has a large effect on the measured dielectric response to theoretically predict the dielectric constant of the rock water air system this rock water interaction must be accounted for by including the effect of the water wetting the rock solid alternatively if the rock water interaction can be eliminated a three component dry rock water and air mixing law can be used to model the dielectric behavior in this laboratory study a chemical treatment is used to change four water wet sandstones into hydrophobic sandstones in three hydrophobic samples the rock water interaction seen in the data for the water wet samples is eliminated and the dielectric constant of the partially saturated sandstones can be simply modeled as a dry rock water air system this experimental study illustrates the importance of the chemical state of the rock surfaces in determining the dielectric behavior of sandstones

kinoshitalite ba mg 3 al2si2 o10 oh f 2 a brittle mica from a manganese deposit in oman paragenesis and crystal chemistry kinoshitalite ideally ba mg 3 al 2 si 2 o 10 oh f 2 was studied in a granulite facies manganese ore associated with calcium bearing magnesian tephroite hausmannite calcite and manganoan clinochlore and in a second assemblage together with hausmannite altered tephroite manganoan diopside and calcite the metamorphic rocks occur enclosed in peridotites of the semail ophiolite sultanate of oman and were metamorphosed during ophiolite obduction single crystal x ray data collected on an inclusion free kinoshitalite of ba 0 99 k 0 06 na 0 01 mg 2 64 mn 0 31 al 2 01 si 2 03 o 10 oh 1 61 f 0 37 cl 0 02 composition yielded a c centered lattice of monoclinic symmetry with a 5 316 1 b 9 230 2 c 10 197 2 a 100 06 1 v 492 6 a 3 and z 1 characteristic of the 1 m polytype the structure was refined in two models assuming complete si al ordering in the space groups c 2 and c 1 allowing for additional twinning the data clearly suggest that in spite of the si al ratio of 1 assumption of complete si al ordering can be rejected two models both in agreement with space group c 2 m causing si al disorder are discussed three dimensional si al disorder would lead to violation of the al avoidance rule and substantial ba displacement the rather well defined ba position capped by two six membered rings of si 3 al 3 o 18 composition suggests one dimensional disorder where completely si al ordered layers exist parallel to 001 the disorder occurs perpendicular to 001 and may be interpreted as random stacking faults

geophysical investigation using resistivity and gpr methods a case study of a lubricant oil waste disposal area in the city of ribeirao preto sao paulo brazil geophysics has been shown to be effective in identifying areas contaminated by waste disposal contributing to the greater efficiency of soundings programs and the installation of monitoring wells in the study area four trenches were constructed with a total volume of about 25 000 m3 they were almost totally filled with re refined lubricating oil waste for approximately 25 years no protection liners were used in the bottoms and laterals of the disposal trenches the purpose of this work is to evaluate the potential of the resistivity and ground penetrating radar gpr methods in characterizing the contamination of this lubricant oil waste disposal area in ribeirao preto sp situated on the geological domain of the basalt spills of the serra geral formation and the sandstones of the botucatu formation geophysical results were shown in 2d profiles the geophysical methods used enabled the identification of geophysical anomalies which characterized the contamination produced by the trenches filled with lubricant oil waste conductive anomalies smaller than 185 m immediately below the trenches suggest the action of bacteria in the hydrocarbons as has been observed in several sites contaminated by hydrocarbons in previously reported cases in the literature it was also possible to define the geometry of the trenches as evidenced by the gpr method direct sampling chemical analysis of the soil and the water in the monitoring well confirmed the contamination in the soil analysis low concentrations of several polycyclic aromatic hydrocarbons pahs were found mainly naphthalene and phenanthrene in the water samples an analysis verified contamination of the groundwater by lead pb the geophysical methods used in the investigation provided an excellent tool for environmental characterization in this study of a lubricant oil waste disposal area and could be applied in the study of similar areas

the 22 july 2009 total solar eclipse modeling d region ionosphere using narrowband vlf observations we present d region ionospheric response to 22 july 2009 total solar eclipse by modeling 19 8 khz signal from nwc very low frequency vlf navigational transmitter located in the australia nwc vlf signal was received at five stations located in and around eclipse totality path in the indian east asian and pacific regions nwc signal great circle paths to five stations are unique having eclipse coverage from no eclipse to partiality to totality regions and the signal is exclusively confined in the low and equatorial regions eclipse induced modulations in nwc signal have been modeled by using long wave propagation capability code to obtain d region parameters of reflection height h and sharpness factor long wave propagation capability modeling showed an increase in h of about 2 3 km near central line of totality 3 0 km in the region near to totality fringe and 2 4 to 3 0 km in the region under partial eclipse using h and wait ionosphere electron density ne profile at the daytime altitude of 75 km showed a decrease in ne by about 58 at a station near totality central line whereas at totality fringe and in partial eclipse region decrease in the ne was between 63 and 71 with respect to normal time values the eclipse associated variations in the h and ne are less in low latitude region as compared to midlatitude the study contributes to explain observations of wave like signature in the d region during an eclipse and difference in the eclipse effect in the different latitude longitude sectors

a comparison of the correlation structure in gpr images of deltaic and barrier spit depositional environments we have used geostatistical analysis of radar reflections to quantify the correlation structures found in 2 d ground penetrating radar gpr images we find that the experimental semivariogram the product of the geostatistical analysis of the gpr data is well defined and can be modeled using standard geostatistical models to obtain an estimate of the range or correlation length and the maximum correlation direction in the 2 d gpr image when we compare the results from geostatistical analysis of gpr data from selected deltaic and barrier spit depositional environments we find different correlation structures in gpr images from different depositional environments gpr images from braid deltas have near horizontal correlation directions and correlation lengths on the order of a few meters in contrast the gpr image of a fan foreset delta has a very long 24 m correlation length and a maximum correlation direction plunging 20 in the gpr images from barrier spits we find maximum correlation directio

coupling ground penetrating radar and fluid flow modeling for oilfield monitoring applications the recent introduction of smart well technology allows for new geophysical monitoring opportunities smart wells which allow zonal production control combined with monitoring techniques capable of capturing the arrival of undesired fluids have the potential to significantly increase the oil recovery we consider borehole radar as a valuable technology for monitoring of the near well region by coupling a drainage process of a bottom water drive reservoir with electromagnetic simulations we find that radar sensors located in the production well can successfully map the fluid saturation evolution in low conductivity reservoirs 0 02 s m a system performance above 80 db is necessary to record reflections in the range of 10 m higher conductivity values strongly reduce the radar investigation depth despite the technical challenges to implement a permanent down hole radar system the potential semi continuous acquisition would make 4d ground penetrating radar a promising technology in capturing the near well fluid dynamics suitable environments are bottom water drive reservoirs with thin oil layer and heavy oil reservoirs exploited by steam assisted gravity drainage processes

low mid latitude d region ionospheric perturbations associated with 22 july 2009 total solar eclipse wave like signatures inferred from vlf observations we present first report on the periodic wave like signatures wls in the d region ionosphere during 22 july 2009 total solar eclipse using jji japan very low frequency vlf navigational transmitter signal 22 2 khz observations at stations allahabad varanasi and nainital in indian sector busan in korea and suva in fiji the signal amplitude increased on 22 july by about 6 and 7 db at allahabad and varanasi and decreased by about 2 7 3 5 and 0 5 db at nainital busan and suva respectively as compared to 24 july 2009 normal day the increase decrease in the amplitude can be understood in terms of modal interference at the sites of modes converted at the discontinuity created by the eclipse intercepting the different transmitter receiver great circle paths the wavelet analysis shows the presence of wls of period 16 40 min at stations under total eclipse and of period 30 80 min at stations under partial eclipse 85 54 totality with delay times between 50 and 100 min at different stations the intensity of wls was maximum for paths in the partially eclipsed region and minimum in the fully eclipsed region the features of wls on eclipse day seem almost similar to wls observed in the nighttime of normal days e g 24 july 2009 the wls could be generated by sudden cutoff of the photo ionization creating nighttime like conditions in the d region ionosphere and solar eclipse induced gravity waves coming to ionosphere from below and above the present observations shed additional light on the current understanding of gravity waves induced d region ionospheric perturbations

ground penetrating radar images of selected fluvial deposits in the netherlands ground penetrating radar gpr surveys have been carried out in order to characterise reflection patterns and to assess the method s potential for imaging palaeofluvial sediments in the mass rhine former confluence area in the southern netherlands the results show that the deposits of meandering braided and transitional river types produce characteristic radar facies representative examples of each of these river types were selected where the gpr data could be directly correlated with sedimentary information derived from exposures and detailed drilling and geomorphological data could be supplied individual channels may be distinguished by the radar facies of their fills the floodplains of the different river types also show a characteristic radar facies in gpr data from the meander floodplain parallel dipping reflections represent point bar structures while irregular intersecting small channel patterns that alternate with parallel continuous reflections are more typical in the braid plain a transitional river type shows characteristics of both of these types typical examples of gpr sections recorded in each of the different fluvial palaeoenvironments are presented in an interpretative radar facies chart

tephroite hausmannite galaxite from a granulite facies manganese rock of the united arab emirates the assemblage tephroite hausmannitess galaxitess has been found in a granulite facies manganese ore body associated with metabasites and quartzrich lithologies the metamorphic rocks are located in the khawr fakkan massif near the northern end of the semail ophiolite united arab emirates u a e metamorphosed at 800 850 c and 6 5 9 kbar the galaxite shows approximately 35 solid solution of hausmannite similar to that reported for jacobsite and franklinite whereas the solid solution of galaxite in hausmannite is maximally 7 the assemblage of tephroite hausmannite and hausmannite galaxite indicates a restricted log fo2 of 9 to 11 which is outside the stability of braunite under similar physico chemical conditions the modal abundance of the minerals and bulk rock chemistry indicate that the present assemblage was formed from the breakdown of fe poor braunitess hausmannitess

new mineral names the following new minerals are discussed in this issue langbanshyttanite pseudolyonsite and yangzhumingite these new minerals have been described in the european journal of mineralogy and are reported here n v chukanov i v pekov e jonsson n v zubkova y e filinchuk d i belakovskiy and d yu pushcharovsky 2011 langbanshyttanite a new low temperature arsenate mineral with a novel structure from langban sweden eur j mineral 23 675 681 the new mineral langbanshyttanite was discovered in a specimen from the langban mine filipstad district varmland county bergslagen ore province sweden the carbonate hosted langban deposit 59 86 n 14 27 e is together with related occurrences in the western part of the palaeoproterozoic bergslagen ore province in south central sweden characterized by anomalously pb as ba be sb rich metamorphosed stratabound fe and mn oxide ores with associated skarn units sulfide assemblages as well as abundant vein and fissure hosted mineral assemblages the name is for langbanshyttan which is the old name of both the mine mining village and smelter that in more recent times has been known plainly as langban langbanshyttan actually means langban s smelter or langban s furnace langbanshyttanite occurs as a very late low temperature species in the deposit it crystallized during the last stage of hydrothermal activity involving metal remobilization in the langban system post dating regional metamorphism of the volcanic hydrothermal ores and their host rocks based on existing evidence these minerals formed at very low temperature and pressure in this case most likely below 70 c the mineral formed in fractures and corrosion veinlets post dating calcite in a mn oxide bearing mn silicate rich rock associated late stage minerals are calcite antigorite sparse euhedral trigonite and a few microscopic aggregates of a so far unidentified as bearing mineral typically both calcite and antigorite exhibit evidence of being partly corroded away prior to langbanshyttanite formation trigonite coeval with langbanshyttanite occurs as sparse euhedral crystals the groundmass to the veinlets or fractures mainly consists

evidence for eight great earthquake subsidence events detected with ground penetrating radar willapa barrier washington a new approach to detect holocene subduction zone earthquakes combines the results from ground penetrating radar gpr vibracores and accelerator mass spectrometry ams dates from a barrier spit located west of willapa bay southwest washington gpr data show a 10 m thick facies of beach sand within which we identify and vibracores confirm beach parallel wave eroded buried scarps mantled with multiple beds of magnetite the eight gpr detected buried scarps are interpreted to be eroded by minor transgressions caused by instantaneous barrier subsidence during earthquakes associated with the juan de fuca plate subducting under the north american plate of these scarps four have been ams dated at 300 1110 2540 and 4250 radiocarbon yr b p no datable material has yet been found for the other four radar detected scarps but we interpolate and extrapolate dates of 1800 3400 5000 and 5800 yr b p

examples of reverse time migration of single channel ground penetrating radar profiles a single channel ground penetrating radar gpr profile portrays a distorted unfocused image of subsurface structure due to apparent position shifts associated with dipping reflectors and to diffractions from corners and edges a focused image may be produced from such data by using any of the migration algorithms previously developed for seismic data we use reverse time migration based on the scalar wave equation field work was performed over a simple stratigraphic soil sequence and a complicated fluvial environment in the migrated images reflector continuity is enhanced and the level of detail available for high resolution interpretation is significantly increased

ground penetrating radar of northern lacustrine deltas ground penetrating radar gpr was used in several selected deltaic sedimentary environments to better understand subsurface stratigraphy and reconstruct former depositional environments the profiles provide high resolution continuous subsurface data on facies thickness and depths orientation of major sedimentary structures postdepositional failure planes and depth of peat deposits field experiments were carried out on six river deltas records from four of the deltas exhibit sedimentary facies a record from one delta shows a possible slump and records from another delta reveal the thickness and stratigraphic relationships of peat deposits the delta types are i sandy wave influenced ii sandy immature wave influenced steeper middle and lower shoreface iii sandy braided and iv gravelly fan foreset in areas of limited subsurface control stratigraphic logs from drill core cutbank exposure or geophysical logs radar profiles can provide big picture perspectives of the subsurface

evidence for microbial enhanced electrical conductivity in hydrocarbon contaminated sediments 1 bulk electrical conductivity of sediments during microbial mineralization of diesel was investigated in a mesoscale laboratory experiment consisting of biotic contaminated and uncontaminated columns population numbers of oil degrading microorganisms increased with a clear pattern of depth zonation within the contaminated column not observed in the uncontaminated column microbial community structure determined from ribosomal dna intergenic spacer analysis showed a highly specialized microbial community in the contaminated column the contaminated column showed temporal increases in bulk conductivity dissolved inorganic carbon and calcium suggesting that the high bulk conductivity is due to enhanced mineral weathering from microbial activity the greatest change in bulk conductivity occurred in sediments above the water table saturated with diesel variations in electrical conductivity magnitude and microbial populations and their depth distribution in the contaminated column are similar to field observations the results of this study suggest that geophysical methodologies may potentially be used to investigate microbial activity

using gpr data as constraints in rmt data inversion for water content estimation a case study in heby sweden this study uses ground penetrating radar gpr data as constraints in the inversion of radio magnetotelluric rmt data to provide an improved model at shallow depth we show that modification of the model regularization matrix using all gpr common offset co reflections can mislead the constrained inversion of rmt data to avoid such problems common mid point cmp gpr data are translated to a resistivity model by introducing a new petrophysical relationship based on a combination of topp s and archie s equations this model is updated through a semi iterative method and is employed as an initial and prior model in the subsequent inversion of rmt data finally a water content model that fits the gpr cmp and rmt data is derived from the resistivity model computed by the constrained inversion of rmt data to assess the proposed scheme it is applied to a synthetic data set then real rmt data collected along an 870 m long profile across a known aquifer situated in the north of heby central sweden are inverted by removing the smoothness constraints across gpr co interfaces or using cmp based inversion thick 10 m vadose and saturated zones are resolved and shown to correlate with logs from nearby boreholes nevertheless the application of our cmp based inversion was the only efficient scheme to retrieve thin 3 m saturated zones and the water table at a depth of 7 15 m in the rmt models the estimated models of water content are in good agreement with the available hydrogeological information in the study area

biogeophysics a new frontier in earth science research 1 biogeophysics is a rapidly evolving earth science discipline concerned with the geophysical signatures of microbial interactions with geologic media it spans the established disciplines of geomicrobiology biogeoscience and geophysics biogeophysics research in the last decade has confirmed the potential for geophysical techniques to measure not simply the physical and chemical properties of the subsurface as already well established but also to detect microbes microbial growth and microbe mineral interactions thus representing a major paradigm shift in geophysical thinking in this review we begin by defining biogeophysics and provide a historical perspective we then consider microbial alterations of petrophysical properties as such alteration is the source of most biogeophysical signals our review then focuses on geophysical interrogation of microbial processes including the direct detection of microbial cells and biofilm formation microbial metabolic by products microbe mediated redox processes and biogeochemical and microbe mineral transformations we conclude by discussing challenges opportunities and potential new applications of biogeophysics to the exploration of life in extreme environments e g the deep biosphere the cryosphere and other planets we find that published biogeophysics studies to date are mostly observation based presenting only empirical relationships between microbial and geophysical variables future research endeavors must focus on developing theoretical and or numerical models for predicting geophysical signals arising from microbial activity

study of the equatorial and low latitude electrodynamic and ionospheric disturbances during the 22 23 june 2015 geomagnetic storm using ground based and spaceborne techniques we use a set of ground based instruments global positioning system receivers ionosondes magnetometers along with data of multiple satellite missions swarm c nofs dmsp guvi to analyze the equatorial and low latitude electrodynamic and ionospheric disturbances caused by the geomagnetic storm of 22 23 june 2015 which is the second largest storm in the current solar cycle our results show that at the beginning of the storm the equatorial electrojet eej and the equatorial zonal electric fields were largely impacted by the prompt penetration electric fields ppef the ppef were first directed eastward and caused significant ionospheric uplift and positive ionospheric storm on the dayside and downward drift on the nightside furthermore about 45 min after the storm commencement the interplanetary magnetic field imf bz component turned northward leading to the eej changing sign to westward and to overall decrease of the vertical total electron content vtec and electron density on the dayside at the end of the main phase of the storm and with the second long term imf bz southward turn we observed several oscillations of the eej which led us to conclude that at this stage of the storm the disturbance dynamo effect was already in effect competing with the ppef and reducing it our analysis showed no significant upward or downward plasma motion during this period of time however the electron density and the vtec drastically increased on the dayside over the asian region we show that this second positive storm was largely influenced by the disturbed thermospheric conditions

ground penetrating radar for environmental applications abstract ground penetrating radar gpr is a near surface geophysical technique that can provide high resolution images of the dielectric properties of the top few tens of meters of the earth in applications in contaminant hydrology radar data can be used to detect the presence of liquid organic contaminants many of which have dielectric properties distinctly different from those of the other solid and fluid components in the subsurface the resolution approximately meter scale of the radar imaging method is such that it can also be used in the development of hydrogeologic models of the subsurface required to predict the fate and transport of contaminants gpr images are interpreted to obtain models of the large scale architecture of the subsurface and to assist in estimating hydrogeologic properties such as water content porosity and permeability its noninvasive capabilities make gpr an attractive alternative to the traditional methods used for subsurface characterization

field evidence for geophysical detection of subsurface zones of enhanced microbial activity 1 geochemical data from closely spaced vertical intervals in a hydrocarbon impacted aquifer were used to assess the relationship between bulk conductivity and zones of enhanced microbial activity the bulk conductivity was measured using in situ vertical resistivity probes microbial activity was verified using terminal electron acceptors nitrate sulfate iron and manganese dissolved inorganic carbon dic and major ion chemistry peaks in bulk conductivity in the aquifer overlapped with zones where nitrates and sulfates were depleted total petroleum hydrocarbon iron manganese dissolved ions and dic were elevated suggesting a link between higher electrical conductivity and zones of enhanced microbial activity stimulated by the presence of hydrocarbon thus the subsurface expression of microbial activity is apparently recorded in the bulk conductivity measurements our results argue for combining geophysics with biogeochemistry studies to delineate subsurface zones of enhanced microbial activity

mine tailings integrated investigations the case of rio tailings panasqueira mine central portugal abstract mining generates huge quantities of waste materials from ore extraction and milling operations which accumulate in tailings and open impoundments the risks associated with mine tailings have different nature namely stability rupture surface and groundwater contamination acid mine drainage amd and precipitation of secondary minerals in fact catastrophic failure of tailings impoundments has occurred transporting slurry dissolved metals and fine reactive metal particles to the environment often deposition conditions of old mine tailings are unknown and monitoring is deficient or even inexistent thus in order to prevent accidents it is necessary to establish the internal structure that is mapping tailings impoundment internal sediment structures limits and stratigraphy seepage and pathway locations bedrock depth and topography estimates and actual deposition conditions of the tailings owing to the complexity of the problem only integrated approaches can investigate and monitor comprehensively the characteristics and evolution of mine tailings and its impacts on the environment as this is a multidisciplinary problem strategies should consider integrated studies such as geophysics geochemistry and borehole surveys however data from these sources must be interpreted together in a gis database to provide better models and an enhanced overall knowledge of the studied structures it is proposed to test and validate such a methodology in a case study panasqueira mine central portugal and to contribute to the decision making process of environmental and civil protection agencies with responsibilities in the assessing prevention mitigation and controlling the potential and actual effects of tailings spills on the environment

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

crystal chemical variations in ba rich biotites from gabbroic rocks of lower crust ivrea zone nw italy biotites from mafic rocks occurring at different stratigraphic levels of the ivrea verbano mafic complex are studied the rocks are gabbros and diorites all the biotites are intermediate between phlogopite and annite 0 28 fe mg fe 0 66 biotites from gabbros are enriched in bao and tio2 up to 7 14 and 9 32 wt respectively with respect to those of the diorites up to 1 26 and 6 26 wt respectively systematic compositional variations support the substitution model 2ivsi ivr2 2ival viti r2 fe mg mn in gabbros and ivsi vial ival viti in diorites a predominance of disordered stacking sequences coexisting with 1m 2m1 and 3t polytypes was observed in all biotites it was possible to carry out structural refinements only on three biotites 2m1 from diorites r values between 2 68 and 3 77 and one biotite 1m from gabbros r value 3 09 it was shown that 1 the reduced thickness of the tetrahedral sheet in ba rich biotites supports the coupled substitution ivsi xiik ival xiiba 2 the interlayer site geometry is affected by the whole layer chemistry and does not reflect only local chemical variations 3 in two samples of the 2m1 polytype the m 1 octahedral site is larger and more distorted than the m 2 sites because of the preferential ordering of fe2 in the m 1 site whereas one sample shows complete cation disorder in the octahedral sites biotite 1m shows that fe2 can also be located in the m 2 site some of the differences between the biotites of gabbros and diorites e g ba concentration and exchange vectors may be linked to the host rock composition and to its crystallization process biotite occurs in trace amounts in gabbros and its crystallization is related to the interstitial melt which contributed to the adcumulus growth of the main rock forming phases and became highly enriched in k ba and ti diorites are the result of equilibrium crystallization of a residual melt rich in incompatible elements where biotite is a major constituent

composition of barian mica in multiphase solid inclusions from orogenic garnet peridotites as evidence of mantle metasomatism in a subduction zone setting multiphase solid inclusions in minerals formed at ultra high pressure uhp provide evidence for the presence of fluids during deep subduction this study focuses on barian mica which is a common phase in multiphase solid inclusions enclosed in garnet from mantle derived uhp garnet peridotites in the saxothuringian basement of the northern bohemian massif the documented compositional variability and substitution trends provide constraints on crystallization medium of the barian mica and allow making inferences on its source barian mica in the multiphase solid inclusions belongs to trioctahedral micas and represents a solid solution of phlogopite kmg3 si3al o10 oh 2 kinoshitalite bamg3 al2si2 o10 oh 2 and ferrokinoshitalite bafe3 al2si2 o10 oh 2 in addition to ba 0 24 0 67 apfu mica is significantly enriched in mg xmg 0 85 to 0 95 cr 0 03 0 43 apfu and cl 0 04 0 34 apfu the substitution vector involving ba in the i site which describes the observed chemical variability can be expressed as bafeivalclk 1mg 1si 1 oh 1 a minor amount of cr and vial enters octahedral sites following a substitution vector vi cr al 2 vi mg fe 3 towards chromphyllite and muscovite as demonstrated by variable ba and cl contents positively correlating with fe barian mica composition is partly controlled by its crystal structure textural evidence shows that barian mica together with other minerals in multiphase solid inclusions crystallized from fluids trapped during garnet growth the unusual chemical composition of mica reflects the mixing of two distinct sources 1 an internal source i e the host peridotite and its garnet providing mg fe al cr and 2 an external source represented by crustal derived subduction zone fluids supplying ba k and cl at uhp uht conditions recorded by the associated diamond bearing metasediments c 1100 c and 4 5 gpa located above the second critical point in the pelitic system the produced subduction zone fluids transporting the elements into the overlying mantle wedge had a solute rich composition with properties of a hydrous melt the occurrence of barian mica with a specific chemistry in barium poor mantle rocks demonstrates the importance of its thorough chemical characterization

influence of oil wettability upon spectral induced polarization of oil bearing sands the presence of oil in an unconsolidated granular porous material like a sand changes both the resistivity of the material and the value of the phase lag between the current and the voltage we performed laboratory experiments to investigate the influence of oil wettability and water saturation upon the complex resistivity of oil bearing sands in the frequency range 1 mhz 1 khz for a sand saturated by a nonwetting oil both the resistivity and the magnitude of the phase increase with the oil saturation as expected from theoretical considerations in the case of a sand partially saturated by a wetting oil we found that both the magnitude of the phase and the resistivity decrease with the oil saturation the quadrature conductivity decreases with the oil with the same trend in presence of wetting and nonwetting oils for relative water saturation above 0 5 in the case of a nonwetting oil the results are quantitatively predicted by available theories in the case of a wet oil our results could be inte

coupled hydrogeophysical inversion using time lapse magnetic resonance sounding and time lapse gravity data for hydraulic aquifer testing will it work in practice 1 temporal changes in water content can be directly related to the time lapse signals retrieved using magnetic resonance sounding tl mrs and relative gravimetry tl rg previous studies suggest that tl rg measurements can potentially provide accurate estimates of aquifer characteristics in an aquifer pumping test experiment when used in a coupled hydrogeophysical inversion approach however these studies considered highly idealized conditions the aim of this paper is twofold first we investigate three major issues which likely limit the practical utility of tl rg for pumping test monitoring partially penetrating pumping wells in anisotropic aquifers delayed drainage effects and typical data errors for tl rg second we introduce tl mrs in a similar coupled hydrogeophysical inversion framework and compare the performance of tl mrs and tl rg for pumping test monitoring for this purpose we consider a virtual pumping test for which we generate synthetic drawdown tl mrs and tl rg observations and subsequently determine the aquifer parameters in an inverse parameter estimation approach the inclusion of tl rg and tl mrs data did slightly improve parameter estimates for the specific yield and hydraulic conductivity when considering a fully penetrating well and minimal data error using more conservative tl rg and tl mrs data error estimates according our own field experience strongly limited the informative value of the tl rg data tl mrs data was less affected by this for a partially penetrating well under anisotropic conditions parameter uncertainty could be reduced more effectively compared to a fully penetrating well delayed drainage effects did not limit the ability of the tl mrs and tl rg data to reduce parameter uncertainty significantly the incorporation of representative measurement error correlation in the tl rg data did not affect its informative value a local sensitivity analysis showed that observations were most sensitive to the pumping rate and the thickness specific yield and hydraulic conductivity of the aquifer the inclusion of tl mrs data proved to be more effective to constrain the aquifer parameters compared with tl rg the inclusion of both tl rg and tl mrs had limited added value compared to tl mrs only we conclude that this particular application of coupled hydrogeophysical inversion has limited potential for tl rg while tl mrs appears to be a more promising method

a new concept in modeling the dielectric response of sandstones defining a wetted rock and bulk water system experimental data for the real part of the dielectric constant k of three sandstone samples are considered as a function of the level of water saturation sw in the frequency range 60 khz to 4 mhz existing theoretical models have previously shown poor agreement with k versus sw data for rock samples undoubtedly due to the complexity involved in adequately accounting for geometrical and electrochemical effects in analyzing the data presented here we find a pronounced increase in k in the low saturation region which in all cases can be attributed to the establishment of geometrical and surface effects associated with the rock water interface when this increase in k is accounted for by defining wetted matrix parameters the data show excellent agreement with existing theoretical models

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

evolution of biogenic gases in peat blocks inferred from noninvasive dielectric permittivity measurements 1 peatlands contain methanogenic archea responsible for generating significant amounts of free phase biogenic gases for example methane and carbon dioxide but considerable uncertainty still exists regarding the mechanisms of formation and spatial distribution of these gases within the soil matrix we demonstrate the effectiveness of a new method to record noninvasively the evolution spatial distribution and emission patterns of biogenic gases in a peat soil a peat block 0 022 m3 was extracted from a large freshwater peatland in maine the bulk dielectric permittivity at 1 2 ghz for multiple slices of the block was measured noninvasively 1 as temperature was increased 2 c d 1 from 5 c to 21 c and 2 for a subsequent 2 month period during which temperature was held constant at 21 1 c methane emissions at the surface and peat surface deformation were monitored concurrently using a portable methane detector and a grid of surface elevation rods respectively our results demonstrate that 1 the measurement of electromagnetic wave traveltimes across a peat block offers a unique and more accurate when compared to surface deformation measurements way to monitor gasdynamics and spatial gas distribution within a peat block without any disturbance to the natural gas regime 2 the ebullition under our experimental conditions seems to preferentially occur from the near surface peat and shows some correspondence with changes in atmospheric pressure and 3 the ebullition flux exhibits periodicity suggesting that it may be predictable and quantifiable which could assist climate modeling efforts our findings are consistent with previous studies based on gasdynamics in peat soils including gas volumes and fluxes associated with biogenic gas ebullition

long duration geomagnetic storm effects on the d region of the ionosphere some case studies using vlf signal the present work investigates the effects of long duration geomagnetic storms on vlf signal during ionospheric sunrise time commonly known as d layer preparation time dlpt depth the vlf signal at 19 8 khz transmitted from northwest cape australia and received at a low latitude station tripura india is used for the present analysis the data for the analysis are selected from november 2008 to october 2011 in the active period of the geomagnetic storms the average dlpt depth is found to have a negative correlation coefficient of 0 91 with geomagnetic ap index it is also found that with each 10 unit increase of ap index the dlpt depth the day and night asymmetry level changes by 1 25 db the results are supported with modeled international reference ionosphere iri electron density data and dlpt depth at 71 km height for the three positions namely receiver position signal hop position and the transmitter position along the total great circle path it is found that the receiver position electron density is the main controlling factor for dlpt depth the correlation between iri electron density and dlpt depth increases from 0 13 at transmitter position to 0 33 at the first hop position to 0 46 at the receiver position respectively the percentage change of post storm electron density at 71 km height is found to increase by more than 100 at the receiver position the results are discussed on the basis of the electron density changes over the signal propagation path mainly caused by the geomagnetic storms

nighttime ionospheric d region equatorial and nonequatorial 1 nighttime ionospheric d region parameters are found to be generally well modeled by the traditional h and as used by wait and by the u s navy in their earth ionosphere vlf radio waveguide programs new comparisons with nonequatorial mainly all sea vlf path observations reported over several decades are shown to be consistent with the previously determined height h 85 0 km and sharpness 0 63 km 1 these paths include npm hawaii to washington d c omega hawaii and nlk seattle to japan nwc n w australia to madagascar and nba panama to colorado in marked contrast transequatorial path observations even when nearly all sea are found to be often not well modeled for example for omega japan and jji japan to dunedin new zealand the observed amplitudes are markedly lower than those which would be expected from h 85 0 km and 0 63 km 1 or any other realistic values of h and other transequatorial observations compared with modeling include nwc to japan omega hawaii to dunedin and npm hawaii to dunedin it is suggested that the effects of irregularities in the equatorial electrojet may extend down into the nighttime d region and so account for the observed equatorial vlf perturbations through scattering or mode conversion

geostatistical analysis of ground penetrating radar data a means of describing spatial variation in the subsurface we have investigated the use of ground penetrating radar gfr as a means of characterizing the heterogeneity of the subsurface radar data were collected at several sites in southwestern british columbia underlain by glaciodeltaic sediments a cliff face study was conducted in which geostatistical analysis of a digitized photograph of the face and the radar image of the face showed excellent agreement in the maximum correlation direction and the correlation length determined from these two data sets other two dimensional 2 d sections of radar data were divided into sedimentary architectural elements on the basis of the distinct radar appearance of these sedimentary units examples of four sedimentary units were used to obtain semivariograms from the radar data and resulted in maximum correlation lengths between 0 5 and 4 8 m a 3 d radar survey collected over a package of gravel and sand foresets was analyzed to determine the paleoflow direction a correlation length of 4 m was found in that direction

ground penetrating radar monitoring of a controlled dnapl release 200 mhz radar a controlled release of tetrachloroethylene was performed in a saturated natural sandy aquifer to evaluate the effectiveness of various geophysical techniques for detecting and monitoring dense nonaqueous phase liquids dnapls in the subsurface tetrachloroethylene typical of most dnapls has a low relative dielectric permittivity 2 3 which contrasts with the high relative permittivity 80 of the pore water it displaces making it a potential target for detection by ground penetrating radar gpr gpr data were acquired using 200 mhz antennas radar sections collected at different times over the same spatial location clearly show the changes induced by the movement of dnapl in the subsurface temporal changes can be examined through the evolution of a radar data trace collected at a single spatial location normal moveout analysis of common midpoint cmp data demonstrates induced changes in electromagnetic em wave velocities of up to 30 percent caused by the presence of dnapl the distribution o

geospace system responses to the st patrick s day storms in 2013 and 2015 this special collection includes 31 research papers investigating geospace system responses to the geomagnetic storms during the st patrick s days of 17 march 2013 and 2015 it covers observation data assimilation and modeling aspects of the storm time phenomena and their associated physical processes the ionosphere and thermosphere as well as their coupling to the magnetosphere are clearly the main subject areas addressed this collection provides a comprehensive picture of the geospace response to these two major storms we provide some highlights of these studies in six specific areas 1 global and magnetosphere plasmasphere perspectives 2 high latitude responses 3 subauroral and mid latitude processes 4 effects of prompt penetration electric fields and disturbance dynamo electric fields 5 effects of neutral dynamics and perturbation and 6 storm effects on plasma bubbles and irregularities we also discuss areas of future challenges and the ways to move forward in advancing our understanding of the geospace storm time behavior and space weather effects

spatial correlation structure estimation using geophysical and hydrogeological data the large spatial variability of hydraulic properties in natural geologic systems over a wide range of scales and the difficulty of collecting representative and sufficient hydraulic property measurements using conventional sampling techniques render estimation of spatial correlation parameters difficult further compounding the estimation problem is the observation that the integral scale estimate is a function of the measurement support scale to mitigate these problems we investigate the use of tomographic geophysical data in combination with hydrogeological data in the spatial correlation estimation procedure two synthetic case studies were investigated where the scale of the geophysical measurements were varied relative to the scale of the hydrogeological properties the spatial correlation structure parameter estimation procedure was performed in the spectral domain where analysis of data having different support scales and spatial sampling windows was facilitated comparison of the spatial correlation structure parameters estimated from measured data with those of the synthetic aquifers revealed which type of data tomographic hydrogeological or a combination of both was most effective for recovering spatial correlation statistics under different sampling heterogeneity conditions these synthetic case studies suggest that collection of a few tomographic profiles and interpretation of these profiles together with limited well bore data can yield correlation structure information that is otherwise obtainable only from extensive hydrological sampling

perturbations of midlatitude subionospheric vlf signals associated with lower ionospheric disturbances during major geomagnetic storms 1 we examine the effects on the midlatitude ionospheric d region of the 7 april 2000 storm and the halloween storm of late october 2003 by means of the associated perturbations of several subionospheric vlf signals propagating in both the northern and southern hemispheres we use vlf nighttime data from the holographic array for ionospheric lightning research hail located in the united states l 2 3 as well as data from palmer station antarctica l 2 4 on 7 april 2000 a 5 db depression in vlf amplitudes is observed at multiple hail stations with a depression onset that occurs later for vlf signal paths at lower latitudes on both 7 april 2000 and 31 october 2003 fluctuations in the amplitude of the vlf signals are first observed in the premidnight sector and persist through the end of the data recording period dawn the frequency content of the fluctuations is predominantly in the 0 01 to 0 02 hz range but extends up to 0 03 hz increases in the energetic electron flux in the loss cone as measured by the noaa poes satellites are observed on both 7 april 2000 and 31 october 2003 we suggest that both the signal depressions and subsequent fluctuations are associated with variations in the precipitation flux of energetic electrons onto the upper atmosphere auroral activity patterns based on data from the noaa poes satellites show that the equatorward edge of the auroral oval expanded equatorward to lower l shells l 3 during both geomagnetic storms using the auoral activity patterns and multiple vlf lf signal paths we provide evidence that the fluctuations and the signal depression coincide with the equatorward edge of the auroral oval extending over the perturbed vlf lf great circle paths quantitative modeling of subionospheric vlf wave propagation incorporating energetic electron flux measurements and the associated altitude profiles of secondary ionization yields results consistent with the variations in the vlf signal amplitude observed

perturbations to the lower ionosphere by tropical cyclone evan in the south pacific region very low frequency vlf electromagnetic signals from navigational transmitters propagate worldwide in the earth ionosphere waveguide formed by the earth and the electrically conducting lower ionosphere changes in the signal properties are signatures of variations in the conductivity of the reflecting boundary of the lower ionosphere which is located in the mesosphere and lower thermosphere and their analysis is therefore a way to study processes in these remote regions here we present a study on amplitude perturbations of local origin on the vlf transmitter signals npm nlk naa and jji observed during tropical cyclone tc evan 9 16 december 2012 when tc was in the proximity of the transmitter receiver links we observed a maximum amplitude perturbation of 5 7db on jji transmitter during 16 december event from long wave propagation capability model applied to three selected events we estimate a maximum decrease in the nighttime d region reference height h by 5 2 km 13 december npm and maximum increase in the daytime d region h by 6 1 km and 7 5 km 14 16 december jji the results suggest that the tc caused the neutral densities of the mesosphere and lower thermosphere to lift and sink bringing the lower ionosphere with it an effect that may be mediated by gravity waves generated by the tc the perturbations were observed before the storm was classified as a tc at a time when it was a tropical depression suggesting the broader conclusion that severe convective storms in general perturb the mesosphere and the stratosphere through which the perturbations propagate

the effect of vertical measurement resolution on the correlation structure of a ground penetrating radar reflection image 1 geostatistical analysis of a ground penetrating radar reflection image can be used to quantify the maximum correlation direction and the range of horizontal and sub horizontal radar reflections a review of previous work and an analysis of a photograph of layered sediments suggest that the vertical resolution of a radar image strongly affects its lateral correlation structure numerical modeling was used to generate synthetic radar sections and investigate the effect of the vertical resolution of the radar measurement on the link between the correlation structure of the radar reflections and the true correlation structure of subsurface water content the horizontal range of the radar reflections decreased as the vertical resolution improved closely matching that of the water content when the vertical resolution was approximately equal to the vertical range of the water content

subsurface radar propagation deconvolution the frequency dependence of attenuation is typically far greater for subsurface radar waves than for seismic waves since this frequency dependence causes the subsurface radar pulse shape to change as it propagates through the earth conventional wavelet deconvolution techniques are often inadequate to reconstruct the earth s reflectivity series the application of a time variant filter that undoes the effect of frequency dependent attenuation can substantially improve the resolution of subsurface radar data this filter is minimum phase with amplitude characteristics equal to the inverse of the attenuation function of the medium investigated preliminary tests on data from surveys over a water tank an underground mine stope and fractured granite suggest that good results can also be achieved by assuming attenuation is linearly proportional to frequency similar to a constant q model

the need to adapt the exploration model from the oil patch to contaminated site characterization a case from hill afb utah usa for decades the oil industry has employed a working model for hydrocarbon exploration in which large scale geophysical surveys are undertaken prior to a second phase of intensive targeted drilling this latter phase may be conducted in conjunction with further focused geophysical studies the geophysical surveys provide lateral coverage and continuity that are used to drive placement of drilling locations the reason for this approach is simple wells are expensive relative to geophysical surveys also practical limits on lateral coverage preclude optimization of exploration targets based on well information alone