interannual variability of the altimetry derived eddy field and surface circulation in the extratropical north atlantic ocean in 1993 2001 abstract the distribution of surface eddy kinetic energy eke depicts main oceanic surface circulation features the interannual variability of eke and associated geostrophic velocity anomalies in the north atlantic ocean were analyzed to describe the variations in oceanic currents between 1993 and 2002 the sea level anomaly maps of the combined topex poseidon ers 1 2 and topex poseidon alone satellite altimetry data were used to derive eke the study focused on the areas of the gulf stream extension gs north atlantic current nac azores current ac and the northeastern rockall channel and iceland basin and northwestern irminger basin and labrador sea north atlantic the interannual variability of the altimetry derived eke field in the gs extension area reflected the meridional displacements of the gs core described in earlier studies the interannual change of eke in the ac was characterized by high values in 1993 95 followed by lower eke in subsequent years the interannual variability of

regional strike slip in the eastern continental margin of korea and its tectonic implications for the evolution of ulleung basin east sea sea of japan air gun profiles delineate a large scale strike slip fault system along the eastern continental margin of korea this system comprises two right stepping curvilinear master faults hupo and yangsan faults that are closely associated with en echelon nominal faults and reverse faults and folds these structural features indicate two phases of regional deformation in the earlier phase late oligocene to early miocene the margin experienced extensional shear strain with dextral strike slip movements along the hupo and yangsan faults that guided a pull apart opening of the pohangyoungduk basin the later phase deformation late miocene to early pliocene was governed by shortening strain that induced a convergent strike slip reactivation of the hupo fault as well as widespread contractile faulting and folding the regional deformation in the eastern korean continental margin reflects three stages of tectonic evolution of the ulleung basin 1 pull apart opening stage from late oligocene to early miocene 2 rotational opening stage with a differential rotation of the japanese arc in middle miocene and 3 back arc closing stage from the end of middle miocene to present

a comparison of geosat altimeter inferred currents and measured flow at 5400 m depth in the argentine basin abstract a comparison is made between an 11 month duration current meter record obtained near the bottom at 40 27 s 49 25 w in the mid argentine basin in water depth 5400 m and near surface flow inferred from geosat altimeter data the geosat has a repeat path time of 17 days and inferred near surface flow features with periods of 34 days or less should not be detectable thus the current meter record was filtered with a 34 day low pass filter since only fluctuating flows can be inferred with the geosat altimeter data the deep recorded mean current was added to the satellite inferred flow for comparison purposes the deep flow and the altimeter inferred near surface flow agree remarkably well suggesting that for time scales 34 days the flow was nearly barotropic in this region of the south atlantic

block modeling with connected fault network geometries and a linear elastic coupling estimator in spherical coordinates geodetic observations of interseismic deformation provide constraints on the partitioning of fault slip across plate boundary zones the spatial distribution of both elastic and inelastic strain accumulation and the nature of the fault system evolution here we describe linear block theory which decomposes surface velocity fields into four components 1 plate rotations 2 elastic deformation from faults with kinematically consistent slip rates 3 elastic deformation from faults with spatially variable coupling and 4 homogeneous intrablock strain elastic deformation rates are computed for each fault segment in a homogeneous elastic half space using multiple optimal planar cartesian coordinate systems to minimize areal distortion and triangular dislocation elements to accurately represent complex fault system geometry block motions fault slip rates elastic coupling and internal block strain rates are determined simultaneously using a linear estimator with constraints from both geodetically determined velocity fields and geologic fault slip rate estimates we also introduce algorithms for efficiently implementing alternative fault network geometries to quantify parameter sensitivity to nonlinear perturbations in model geometry

characterization of cavities using the gpr lidar and gnss techniques the study of the many types of natural and manmade cavities in different parts of the world is important to the fields of geology geophysics engineering architectures agriculture heritages and landscape ground penetrating radar gpr is a noninvasive geodetection and geolocation technique suitable for accurately determining buried structures this technique requires knowing the propagation velocity of electromagnetic waves em velocity in the medium we propose a method for calibrating the em velocity using the integration of laser imaging detection and ranging lidar and gpr techniques using the global navigation satellite system gnss as support for geolocation once the em velocity is known and the gpr profiles have been properly processed and migrated they will also show the hidden cavities and the old hidden structures from the cellar in this article we present a complete study of the joint use of the gpr lidar and gnss techniques in the characterization of cavities we apply this methodology to study underground cavities in a group of wine cellars located in atauta soria spain the results serve to identify construction elements that form the cavity and group of cavities or cellars the described methodology could be applied to other shallow underground structures with surface connection where lidar and gpr profiles could be joined as for example in archaeological cavities sewerage systems drainpipes etc

gulf stream trajectories measured with free drifting buoys abstract during 1975 78 35 free drifting buoys measured surface currents in the gulf stream region the buoy trajectories trace numerous paths of the stream and show that the stream is strongly influenced by the new england seamounts this influence is manifested as 1 a quasi permanent 100 km southeastward deflection of the stream and the frequent occurrence of a ring meander over the seamounts 2 large amplitude meanders beginning at the seamounts and extending eastward and 3 small 20 km diameter eddies which appear to be generated locally by individual seamounts a chart of the mean temperature field at a depth of 450 m agrees with several of the patterns seen in the buoy trajectories west of the seamounts the mean path of the gulf stream is eastward over the seamounts the path turns sharply northeastward and the isotherms in the stream abruptly diverge

modeling broadscale deformation in northern california and nevada from plate motions and elastic strain accumulation we present a first order method for modeling broadscale deformation consistent with both plate tectonic motions and elastic strain accumulation on plate boundary faults interseismic deformation is assumed to be a superposition of long term rigid body motions between faults defined by angular velocities of spherical plates and backslip on shallow locked portions of faults in an elastic half space this method is applied to 1993 2000 continuous gps data from 35 sites in a profile from the san francisco bay area northern california to eastern nevada deformation is consistent within the 1 mm yr 1 uncertainties of the estimated site velocities with a simple 10 parameter model using 6 rigid plates and 3 locked san andreas system faults

stress modulation on the san andreas fault by interseismic fault system interactions during the interseismic phase of the earthquake cycle between large earthquakes stress on faults evolves in response to elastic strain accumulation driven by tectonic plate motions because earthquake cycle processes induce non local stress changes the interseismic stress accumulation rate on one fault is influenced by the behavior of all nearby faults using a geodetically constrained block model we show that the total interseismic elastic strain field generated by fault interactions within southern california may increase stressing rates on the mojave and san bernardino sections of the san andreas fault within the big bend region by as much as 38 relative to estimates from isolated san andreas models assuming steady fault system behavior since the c e 1857 fort tejon earthquake shear stress accumulated on these sections due only to interaction with faults other than the san andreas reaches 1 mpa 3 times larger than the coseismic and postseismic stress changes induced by recent southern california earthquakes stress increases along big bend sections coincide with the greatest earthquake frequency inferred from a 1500 yr long paleoseismic record and may affect earthquake recurrence intervals within geometrically complex fault systems including the sections of the san andreas fault closest to metropolitan los angeles

application of field geophysics in geomorphology advances and limitations exemplified by case studies abstract during the last decade the use of geophysical techniques has become popular in many geomorphological studies however the correct handling of geophysical instruments and the subsequent processing of the data they yield are difficult tasks furthermore the description and interpretation of geomorphological settings to which they apply can significantly influence the data gathering and subsequent modelling procedure e g achieving a maximum depth of 30 m requires a certain profile length and geophone spacing or a particular frequency of antenna for more than three decades geophysical techniques have been successfully applied for example in permafrost studies however in many cases complex or more heterogeneous subsurface structures could not be adequately interpreted due to limited computer facilities and time consuming calculations as a result of recent technical improvements geophysical techniques have been applied to a wider spectrum of geomorphological and geological settings this paper aims to present some examples of geomorphological studies that demonstrate the powerful integration of geophysical techniques and highlight some of the limitations of these techniques a focus has been given to the three most frequently used techniques in geomorphology to date namely ground penetrating radar seismic refraction and dc resistivity promising applications are reported for a broad range of landforms and environments such as talus slopes block fields landslides complex valley fill deposits karst and loess covered landforms a qualitative assessment highlights suitable landforms and environments the techniques can help to answer yet unsolved questions in geomorphological research regarding for example sediment thickness and internal structures however based on case studies it can be shown that the use of a single geophysical technique or a single interpretation tool is not recommended for many geomorphological surface and subsurface conditions as this may lead to significant errors in interpretation because of changing physical properties of the subsurface material e g sediment water content in many cases only a combination of two or sometimes even three geophysical methods gives sufficient insight to avoid serious misinterpretation a good practice guide has been framed that provides recommendations to enable the successful application of three important geophysical methods in geomorphology and to help users avoid making serious mistakes

high velocity ring shear tests on sand ring shear tests on sand materials have been carried out to show whether there is a change in the behaviour of these materials at high shearing rates and normal stresses this question is relevant to the problem of the mobility of large rock avalanches sturzstroms but is also of more general academic interest a ring shear apparatus of unusual although simple design has been constructed capable of achieving circumferential velocities of 2 m s at normal stresses of up to 200 kpa tests were carried out on two types of coarse sand wet or dry sand rock flour mixtures and polystyrene beads perfect frictional behaviour was observed in all the tests uninfluenced by either velocity or normal stress over the entire range of these variables change in frictional behaviour due to high rate of shearing therefore cannot be used to explain the high observed mobility of sturzstroms des essais de cisaillement circulaire par torsion ont ete effectes afin de decouvrir si un changement ait lieu dans le comportem

determining rheological parameters of debris flow material abstract a 2 0 m diameter steel 30 inverted cone and plate viscometer rheometer was designed constructed and used to test the behaviour of coarse grained debris flow materials a 1 5 scale model machine was also constructed and used to test the internal flow dynamics of the viscometer rheometer and to obtain results for fluids grain fluid mixtures and debris flow fines for fluids and grain fluid mixes our results were similar to those obtained earlier using standard viscometric systems derived rheological parameters for debris flow materials and clay slurries agreed well with those determined from calculation direct measurement and field observation apparent viscosities were shear rate dependent extremely sensitive to water content and as high as 6000 pa s instantaneous stresses within shearing debris flow material varied over a wide range debris flow materials with bimodal grain size distributions had a dilatant plastic rheology those with a low content of coarse material and unimodal grain size distribution or exceptionally high fines content had a plastic or viscoplastic rheology

slip rates and locking depth variation along central and easternmost segments of north anatolian fault while the kinematics of anatolia plate and the north anatolian fault system nafs has been studied extensively the slip rate and locking depth along the nafs are usually assumed constant in the analyses due to the lack of sufficient data this is also partly due to the reasonably good fit of euler small circle and partly due to the lack of spatial resolution of observations to determine slip rates independently from locking depths on the other hand recent geodetic studies show a contrast for locking depth between marmara and other parts of the nafs implying a non uniform locking depth across the nafs in this study we analyse new gps data and homogenously combine available data sets covering the eastern part of the nafs to form the most complete data set in particular we incorporate the first results of turkish real time kinematic gps network cors tr into our data set a detailed analysis of three profiles within the nafs reveals an increase of locking depth in the middle profile to 19 1 3 4 km from 11 9 3 5 km in the easternmost profile while the slip rate is nearly constant 20 22 mm yr 1 which implies a variation of strain rate of 100 nanostrain yr 1 assuming a constant locking depth throughout whole nafs gives an average locking depth of 14 3 1 7 km our best estimates of slip rates in block modelling which takes the variation of locking depths into account are in the range between 22 5 and 22 8 mm yr 1 over eastern part of the nafs

significance of coarse clasts in viscous debris flows abstract debris flows are flowing mixture of water and sediments from clay to boulder sized particles the sediments control both occurrence and characteristics of debris flows however the relevant literature has concentrated mainly on fine debris considering their large fractions in debris flows the significance of coarse clasts 0 005 mm is investigated by comparing the crude debris cd the fractions of aggregation of data collected in 39 tested debris water mixtures leads us to conclude that the coarse clasts can greatly affect the slurrying susceptibility of debris masses and bulk behavior of slurries the debris flow indices id from the cd to rd slurries with maximum grain sizes of 10 and 5 mm decrease by 29 and 17 respectively the cd slurries possess higher yield strength and viscosity than their rd counterparts with the same solid volumetric concentrations cvs the areas inundated by 10 cd slurries with maximum grain sizes of 10 and 5 mm are approximately 17 39 of those of their rd counterparts the excess pore pressures in the rd slurries dissipate more quickly than those in the cd slurries the shape and surface texture of coarse clasts regulate slurrying of debris masses as well as influence their liquefaction potential which in turn has an impact on the mobility and persistence of subsequent slurries the platy flaky debris producing mountain catchments generally experience lower magnitude higher frequency lower cv debris flows of relatively less destructive power and the debris flows dominated by equidimensional clasts are often more powerful and hazardous despite their potentially lower frequency

a debris flow deposit with multiple plug flow channels and associated side accretion deposits a grain dominant debris flow deposit of juvenile basaltic volcaniclastic detritus from a late eocene early oligocene marine surtseyan volcanic pile in north otago new zealand contains multiple semi circular to u shaped channel like structures or relics thereof associated with wedges of asymptotic layers of fine and coarse debris the u shaped structures are interpreted as channel like plug flow zones and the associated wedges are interpreted as abandoned parts of the marginal laminar shear flow zone fine layers and adjacent plug zone coarse layers these appear to have been abandoned by frictional freezing as the plug flow channels migrated laterally in an apparently step like fashion the debris flow and its deposit appear to have been tabular in geometry and the development of multiple transport pathways in debris flows is considered in terms of the geometrical ratio of the width of the flow to the dynamic thickness

application of ground penetrating radar imaging to deepwater turbidite outcrops ground penetrating radar gpr provides a high resolution image of bed scale features within the interior of an outcrop this geophysical technique has been used successfully in fluvial deltaic sequences but its successful use in deepwater deposits is less documented the present paper demonstrates the ability of gpr to define the nature of channel margins and to distinguish internal channel facies at turbidite outcrops in wyoming cretaceous lewis shale usa profiles obtained behind the lewis shale outcrops show channel fills having complex slumped margins between channel sandstones and adjacent levee thin beds as well as onlap of sandstone beds onto the channel margins within the channel fill facies distinguished by gpr vary from interbedded debris flows and turbidites on one side of a channel to cross bedded sandstones on the other side lateral accretion surfaces and onlap features which cannot be observed at the outcrop scale are present on gpr profiles they may represent cross channel sediment transport and deposition within a sinuous channel these examples suggest that when used together with geologic mapping photomosaics and available behind outcrop drilling and logging gpr surveys spanning large outcrops may provide valuable sub seismic scale architectural information for building more robust 3 d models of deepwater reservoirs q 2003 elsevier ltd all rights reserved

geophysical evidence for the lateral distribution of free phase gas at the peat basin scale in a large northern peatland 1 northern peatlands contribute to the global carbon cycle by way of gas emissions in the form of biogenic carbon dioxide and methane originating in the subsurface determining how much gas is present and where it is trapped is essential to understanding the role of northern peatlands on the global carbon cycle particularly in regard to methane cycling in this study spatial variability in free phase gas content was estimated using ground penetrating radar gpr along a 1 4 km transect crossing distinct peat landforms including a bog crest midslope lawn and fen variations in gas content and distribution were observed in landforms crossed by this transect estimated gas content up to 25 by volume was observed in landforms dominated by woody surface vegetation in areas of the midslope lawn the estimated gas content was greater than 15 while estimated gas contents between 0 and 7 were found in the fen changes in estimated gas content of up to 20 were observed over distances of 100 m across a transition between a stand of 10 m tall trees and an adjacent fen the mean of the estimated errors in gas content is 1 3 suggesting that these large changes in estimated gas content between landforms can be clearly determined using geophysical methods a geophysical image of the distribution of free phase across this transect reveals evidence for gas storage in deep peat in intervals as thin as 0 35 m these data support conceptual models based on accumulation and storage of free phase gas in deep peat

rheological properties of mudflows associated with the spring 1980 eruptions of mount st helens volcano washington rheological properties of three recent mudflows at mount st helens were estimated using techniques developed for determining the properties of debris flows based on the geometry of their deposits calculated yield strengths of 1100 1000 and 400 pa maximum flow velocities of 10 to 31 m s volumetric flow rates of 300 to 3400 m s and plastic viscosities of 20 to 320 pa s all compare favorably with measured and estimated values cited in the literature a method for determining likely sites of future mudflow initiation based on these data is outlined

investigating fluvial features with electrical resistivity imaging and ground penetrating radar the guadalquivir river terrace jaen southern spain abstract a geophysical survey has been conducted on the lowest terrace levels and the present day floodplain of the current course of the guadalquivir river passing through the province of jaen spain using two techniques electrical resistivity imaging eri and ground penetrating radar gpr three areas have been selected in one of these sectors los barrios there is an old quarry where there are excellent outcrops that allow for the calibration of the survey techniques facies associations on these outcrops are typical of meandering rivers with sequences of channel fills lateral accretion of point bars and floodplain facies the usefulness of the two methods is analysed and compared as a support for stratigraphic and sedimentological studies the geometry and lithofacies of subsurface deposits were characterised using eri and compared with field observations a total of 5 electrical resistivity imaging profiles were obtained the changes in electric resistivity highlight granulometric differences in terrace sediments this technique can thus be used to identify the morphology of these bodies the lithofacies silt sand or gravel and buried channel pattern in addition 16 gpr profiles using 100 and 250 mhz antennas were acquired indicating terrace morphology and the filling of the sedimentary bodies in a more detailed manner than in eri the study thus allows for inferring the existence of channel migration the lateral accretion of point bars and the presence of vertical accretion deposits attributable to the floodplains

potential and limits of insar to characterize interseismic deformation independently of gps data application to the southern san andreas fault system the evaluation of long wavelength deformation associated with interseismic strain accumulation traditionally relies on spatially sparse gps measurements or on high spatial resolution insar velocity fields aligned to a gps based model in this approach the insar contributes only short wavelength deformation and the two data sets are dependent thereby challenging the evaluation of the insar uncertainties and the justification of atmospheric corrections here we present an analysis using 7 years of envisat insar data to characterize interseismic deformation along the southern san andreas fault saf and the san jacinto fault sjf in southern california where the saf bifurcates onto the mission creek mcf and the banning bf fault strands we outline the processing steps for using insar alone to characterize both the short and long wavelength deformation and evaluate the velocity field uncertainties with independent continuous gps data insar line of sight los and continuous gps velocities agree within 1 2 mm yr in the study area suggesting that multiyear insar time series can be used to characterize interseismic deformation with a higher spatial resolution than gps we investigate with dislocation models the ability of this mean los velocity field to constrain fault slip rates and show that a single viewing geometry can help distinguish between different slip rate scenarios on the saf and sjf 35 km apart but multiple viewing geometries are needed to differentiate slip on the mcf and bf 12 km apart our results demonstrate that interseismic models of strain accumulation used for seismic hazards assessment would benefit from the consideration of insar mean velocity maps

present day crustal deformation along the philippine fault in luzon philippines abstract the philippine fault results from the oblique convergence between the philippine sea plate and the sunda block eurasian plate the fault exhibits left lateral slip and transects the philippine archipelago from the northwest corner of luzon to the southeast end of mindanao for about 1200 km to better understand fault slip behavior along the philippine fault eight gps surveys were conducted from 1996 to 2008 in the luzon region we combine the 12 yr survey mode gps data in the luzon region and continuous gps data in taiwan along with additional 15 international gnss service sites in the asia pacific region and use the gamit globk software to calculate site coordinates we then estimate the site velocity from position time series by linear regression our results show that the horizontal velocities with respect to the sunda block gradually decrease from north to south along the western luzon at rates of 85 49 mm yr in the west northwest direction this feature also implies a southward decrease of convergence rate along the manila trench significant internal deformation is observed near the philippine fault using a two dimensional elastic dislocation model and gps velocities we invert for fault geometries and back slip rates of the philippine fault the results indicate that the back slip rates on the philippine fault increase from north to south with the rates of 22 37 and 40 mm yr respectively on the northern central and southern segments the inferred long term fault slip rates of 24 40 mm yr are very close to back slip rates on locked fault segments suggesting the philippine fault is fully locked the stress tensor inversions from earthquake focal mechanisms indicate a transpressional regime in the luzon area directions of 1 axes and maximum horizontal compressive axes are between 90 and 110 consistent with major tectonic features in the philippines the high angle between 1 axes and the philippine fault in central luzon suggests a weak fault zone possibly associated with fluid pressure

correlation between surface gulf stream and bottom flow new 5000 meters depth abstract spectral analyses of three long term 8 months deep 5 km current meter records located on the scotian rise 40 n 62 w and a time series of the average northerly position of the surface gulf stream system obtained from analyses of satellite data give evidence at a period of about 2 weeks that the gulf stream system is influencing the ocean in this region from the surface to the bottom

open channel flow of bingham fluids applications in debris flow research the results of a numerical simulation of open channel flow of bingham fluids provide improved capabilities for analyzing muddy debris flows and their depositis and for routing debris flows because of limitations of the phenomenonological bingham model results are deemed applicable to mud rich debris flows only most published field estimates of debris flow rheological bingham properties depend on application to natural channels of analytical solutions for flow through channels with either circular or very wide channel cross sections lack of a general solution for flow of bingham fluids in channels with realistic shapes has restricted capabilities in debris flow modeling and field data analysis numerical solutions permit generalization and extension of analytical solutions to channels of arbitrary cross sectional form without loss of accuracy the numerical model fidap utilizes a well established finite element formulation of the non newtonian fluid flow problem and reproduces available analytical

japan sea opening history and mechanism a synthesis the respective tectonic effects of back arc spreading and continental collision in asia are considered either as two independent processes or as closely interrelated extrusion tectonics assumes that the opening of the south china sea and the left lateral motion along the red river fault are geometrically linked in a pull apart manner this model is not accepted by several workers because the structural link between the two processes is not clearly demonstrated in the case of the japan sea we can show without ambiguity that back arc opening was controlled by large intracontinental strike slip faults which can be easily understood as effects of the india asia collision far from the indenter the japan sea opened in the early miocene in a broad pull apart zone between two major dextral strike slip shear zones the first one extends from north sakhalin to central japan along 2000 km it has accommodated about 400 km of finite displacement deformation along it varies from dextral transpression in the north to dextral transtension in the south the second is between korea and sw japan and has accommodated a smaller displacement of about 200 km the extensional domain in between lies in the back arc region of japan distributed stretching of the arc crust resulted in the formation of most of the japan sea while localized oceanic spreading at the southern termination of the eastern transpressional shear zone shaped the japan basin the first oceanic crust was formed in a small triangle based on the eastern shear zone and spreading propagated westward inside the pull apart region timing of oceanic crust formation of formation of the dextral shear zones and of block rotation in between as well as the internal structure of the basins and the geometry of deformation along the master shear zones are used to reconstruct the opening history this evolution is discussed by comparison to other manifestations of the arc and back arc activity such as the history of sedimentation and volcanism the paper then suggests that the collision of india can have tectonic consequences as far north as japan and sakhalin and describes the geometrical relation of back arc opening there and diffuse extrusion

gpr and high resolution seismic integrated methods to understand the liquefaction phenomena in the mirabello village earthquake ml 5 9 2012 abstract we performed a geophysical survey in mirabello a village of emilia romagna region of northern italy to study the soil affected by the ml 5 9 earthquake of 2012 specifically the formation of surface ruptures by sand ejection due to the liquefaction of shallow subsurface layers the investigation was carried out using ground penetrating radar and seismic reflection refraction techniques this work confirms the importance of electromagnetic waves to map the shallow subsurface extent of fractures and liquefied sand bodies while the high resolution seismic reflection profile allowed us to map the fractures at depth the result obtained by tomographic inversion of first arrivals of seismic data has been compared with a ground penetrating radar section acquired in the same place furnishing complementary information for the interpretation of the section

sedimentology of the neoproterozoic c 580 ma squantum tillite boston basin usa mass flow deposition in a deep water arc basin lacking direct glacial influence abstract the squantum tillite c 593 570 ma consists of thick up to 215 m massive and crudely stratified diamictites conformably interbedded with subaqueously deposited conglomerates and sandstones within a thick 7 km boston basin fill which is dominated by argillite turbidites the squantum tillite was first interpreted as being glacigenic in origin in 1914 because of the presence of diamictites argillites were interpreted as glaciolacustrine varves with rare ice rafted debris and conglomerates as glaciofluvial outwash more recently these have been shown to be the product of deep marine mass flow processes with no glacial influence yet because of its age equivalence with the deep marine glacially influenced gaskiers formation the squantum tillite is still seen by some as supporting evidence for a widespread snowball earth event at c 580 ma new sedimentological work confirms that conglomerate and sandstone facies are deep marine sediment gravity flows genetically related to massive homogeneous and crudely stratified heterogeneous diamictites produced subaqueously by downslope mixing of gravel and cobbles with muddy facies rare horizons of ice rafted debris in thin bedded and laminated turbidite facies interbedded with thick debrites show a weak but positive correlation of lamina thickness with grain size suggesting these facies are non glacial co genetic debrite turbidite couplets a significant volcanic influence on sedimentation is identified from reworked lapilli tuff beds and reworked ash in turbidites the depositional setting of the squantum tillite appears to be that of a submarine slope fan setting in an open marine volcanic arc basin receiving large volumes of poorly sorted sediment on the mid latitude active margin of gondwana no direct glacial influence is apparent

facies control on seismites in an alluvial aeolian system the pliocene dunefield of the teruel half graben basin eastern spain abstract the recognition of seismically induced soft sediment deformation structures ssds in sedimentary successions characterized by different facies and hence by different rheology is challenging this is the case for high porosity and high permeability aeolian facies interbedded with muddy wet interdune deposits and alluvial conglomerates and sandstones several types of ssds have been studied in two exposures of the upper pliocene 2 9 2 6 ma sediments of a fault bounded intracontinental aeolian dune field in the teruel basin iberian chain eastern spain among ssds load and fluid escape structures apart from several animal tracks have been recognized those structures show an irregular distribution through the studied stratigraphic sections being scarce in homogenous aeolian sands and frequent in water related facies a detailed study of the distribution and geometry of ssds and their relationships with respect to the stratigraphic architecture and facies has allowed a critical discrimination of trigger mechanisms i e biological or physical overloading vs earthquakes the seismically induced structures are concentrated into seven deformed beds showing an uneven lateral distribution and geometry closely controlled by the hosting sedimentary facies and their rheology these seismites resulted from liquefaction during moderate earthquakes estimated magnitude from 5 0 to 6 8 the most probable seismogenic source was the sierra del pobo normal fault zone located 2 km to the east results show how an appropriate recognition of sedimentary facies is crucial to understand the lateral variability of seismites in sedimentary environments characterized by sharp facies changes

a hybrid laser tracking gps location method allowing gpr acquisition in rugged terrain ground penetrating radar images of geologic structures provide information about the crucial third dimension which is inaccessible to geologic mapping in order to correlate images with geologic mapping photomosaics and behind outcrop borehole logs radar profiles must be accurately mapped moreover accurate profile elevations are required during processing to avoid introducing into the radar image false structures associated with topographic relief in recent years radar station locations and elevations have been obtained very efficiently from a self tracking laser theodolite operated at the same time the radar data are being acquired the required physical link between radar and laser systems however may make such a system unusable in areas of rugged terrain

active faulting in the western pyrenees france paleoseismic evidence for late holocene ruptures abstract we have identified a 50 km long active fault scarp called herewith the lourdes fault between the city of lourdes and arette village in the french pyrenees this region was affected by large and moderate earthquakes in 1660 io viii ix msk 64 in 1750 io viii msk 64 and in 1967 md 5 3 io viii msk 64 most earthquakes in this area are shallow and the few available focal mechanism solutions do not indicate a consistent pattern of active deformation field investigations in active tectonics indicate an east west trending and up to 50 m high fault scarp in average made of 3 contiguous linear fault sub segments to the north the fault controls quaternary basins and shows uplifted and tilted alluvial terraces deviated and abandoned stream channels of the southern block are likely due to the successive uplift of the northern block of the fault paleoseismic investigations coupled with geomorphic studies georadar prospecting and trenching along the fault scarp illustrate the cumulative fault movements during the late holocene trenches exhibit shear contacts with flexural slip faulting and thrust ruptures showing deformed alluvial units in buried channels 14c dating of alluvial and colluvial units indicates a consistent age bracket from two different trenches and shows that the most recent fault movements occurred between 4221 bc and 2918 bc fault parameters and paleoseismic results imply that the lourdes fault and related sub segments may produce a mw 6 5 to 7 1 earthquake fault parameters imply that the lourdes fault segment corresponds to a major seismic source in the western pyrenees that may generate earthquakes possibly larger than the 1660 historical event

sandy gravelly mass flow deposits in an ice marginal lake saalian leuvenumsche beek valley veluwe the netherlands with emphasis on plug flow deposits abstract in three pits in the leuvenumsche beek valley near ermelo and elspeet massive and diffusely banded clean gravelly sands found in association with sandy sediments showing some similarities to the bouma sequence were interpreted as originating from sediment gravity flows the flows which came to rest on a ca 6 paleoslope probably originated from slumping of parts of the ice pushed ridges at either side of an ice marginal lake major characteristic features in the three sand pits studied are u shaped channel forms with a maximum depth and width of 10 25 rmm the fills consist of sand and gravels locally containing giant sand clasts the sediments just below the base of these channel forms are commonly distorted and folded especially the massive more sandy fills are surrounded by a finer grained diffusely bedded and inversely graded zone these sedimentary features suggest that rigid sediment plugs sheared downslope generating a finer grained shear zone around the plug scouring a slide scar till its present semi cylindrical form and preserving the steep sides exceeding the angle of repose of the channel form by freezing the u shaped channel forms plugged troughs are locally overlain by shallower gently sided trough structures with mainly diffusely banded infillings very shallow and often smaller troughs are found again on top of these massive and diffusely banded infillings the sediments in these troughs consist of repetitions of two types of microsequences 1 thickly bedded sequences of normally graded massive sands near horizontal stratifications plane beds and cross bedded sets and 2 thinly bedded sequences of relatively thick units t a and thin units t c and t d of the bouma sequence the repetitions of the microsequences are interpreted as flow pulsations upwards thinning of the sequence together with a finer grain size may point to waning flow conditions their association with plugged troughs is suggestive of retrogressive flow slides

laboratory analysis of mudflow properties a rotational viscometer has been designed for laboratory measurements of the rheological properties of natural mudflow deposits in colorado the mudflow matrices comprised of silt and clay particles are sheared under temperature controlled conditions at volumetric sediment concentrations ranging from 0 10 0 45 this study stresses the importance of conducting rheological measurements at low rates of shear because 1 those are the conditions found in natural channels and 2 they avoid the slippage problems observed at large sediment concentrations at low rates of shear the bingham model is fitted to the measured rheograms and both the viscosity and yield stress increase exponentially with the sediment concentration of the fluid matrix both the yield stress and the viscosity increase by three orders of magnitude as the volumetric concentration of sediments in the fluid matrix changes from 10 to 40 the addition of sand particles does not significantly alter the rheological properties of the matrix unless the volumetric concentration of sands exceeds 0 20

early post impact sedimentation around the central high of the mjolnir impact crater barents sea late jurassic abstract the mjolnir bolide created the 40 km diameter mjolnir crater when it impacted the black mostly anoxic clays of the hekkingen formation in the paleo barents sea about 142 2 6 million years ago the normally calm 300 500 m deep epicontinental depositional environment was suddenly disrupted by the dramatic effect of the impact resulting in a brief period of extreme sediment reworking and redeposition the hypoxic to anoxic depositional conditions characteristic of the hekkingen formation returned to the impact site soon after the collapse when the major modification phases of the mjolnir crater were completed we have studied a shallow core 121 m long retrieved from the flanks of the central high in the mjolnir crater the core shows a complex depositional succession of the ragnarok formation which is related to both the uplift and the subsequent collapse and drowning of the central high the basal part of the core consists of chaotically organised large folded slabs of pre impact substrate which we infer to be related to the rapid steepening of the slope of the central high during its rising shortly after the impact the slump deposits are overlain by a diamict which is interpreted to originate from debris flows that originate by liquefaction and subsequent remoulding and remobilisation of sediment from the collapsing central high the diamict is in turn covered by a brecciated graded mudstone that records the action of impact related tsunami and the subsequent submergence of the impact crater a sequence of mainly debris flow and turbidite deposits separates the impact related deposit from the overlying shelf sediments of the hekkingen formation and forms the last post impact sedimentary recorder of the presence of a central high in the crater

paleomagnetism of tertiary rocks on the korean peninsula tectonic implications for the opening of the east sea sea of japan abstract two different distributions of declinations with dual polarities are found in the tertiary rocks of the yeonil basin and yangnam basin along the yangsan fault in the southeastern part of the korean peninsula these are northward declinations in the middle miocene yeonil group and strong eastward declinations in the early miocene yangbuk group and in the eocene volcanic rocks this is interpreted by invoking 1 the yangsan fault as a dextral wrench fault system by spreading in the uleung basin of the east sea sea of japan and 2 a clockwise vertical rotation caused by the movement of the fault at around 17 3 ma just prior to the sedimentation of the yeonil group the timing of the deflection found in korea is distinguished from that in southeastern and northwestern japan at around 15 ma two stages of spreading are thus constrained in the east sea area parallel at 23 15 ma and pivotal at around 15 ma crustal thinning also occurred a reliable pole position 84 9 n 292 6 e d p d m 3 3 4 8 for the miocene about 15 ma in korea is obtained from the yeonil group

early neogene biochemostratigraphy of pohang basin a paleoceanographic response to the early opening of the sea of japan east sea abstract the location of the pohang basin near the korea strait in the southwest of the sea of japan east sea makes this area appropriate for providing a record of paleoenvironmental biotic changes associated with the early neogene 16 5 ma opening of this gateway to the pacific ocean stable isotopic and planktonic foraminiferal records are presented that assist with the understanding of paleoenvironmental changes in the sea of japan resulting from the opening of the korea strait the oldest sediments of early neogene age of the pohang basin overlie cretaceous basement and are early miocene 16 5 ma shallow estuarine facies containing a benthic foraminiferal assemblage dominated by ammonia beccarii l the oldest early neogene planktonic foraminiferal assemblages in the basin are 16 5 ma in age latest early miocene foraminiferal zone n8 the migration of these planktonic assemblages to the sea of japan at that time appears to have resulted from the initial opening of the korea strait the overlying early neogene marine sequence of the pohang basin extends from 16 5 ma zone n8 through 14 ma zone n10 change in the oxygen isotopic record of the pohang basin sequence suggests strong local paleoenvironmental control related to the early opening of the korea strait early middle miocene isotopic temperatures of planktonic foraminifera are relatively cool at 15 ma at a time when global temperatures were high in the middle low latitude regions it was not until 14 8 ma that isotopic temperatures of planktonic foraminifera increased markedly this distinct warming is inferred to reflect the major intrusion of the kuroshio current into the sea of japan probably as a result of further critical opening and deepening of the korea strait at this time planktonic foraminifera increased in abundance reflecting expanding oceanic influence a cooling that followed at 14 5 ma when the strait was well open is unlikely to reflect local tectonic control on the paleoceanography but global cooling during the early middle miocene associated with the expansion of the east antarctic ice sheet

general solutions for viscoplastic debris flow theoretical velocity profile and theoretical pressure and concentration distributions for steady uniform debris flow in wide channels are derived from a generalized viscoplastic fluid gvf model without imposing bagnold s assumption of constant grain concentration good agreement between the theoretical velocity profile and the experimental data of japanese scientists strongly supports the validity of both the gvf model and the proposed method of solution from the model it is shown that both bingham and bagnold versions or submodels of the gvf model can be used to simulate debris flow at the dynamic state although bagnold s dilitant submodel appears to fit the japanese data better than the bingham submodel for flow of noncohesive grains the choice between them is by no means clear cut no matter which submodel is used a full understanding of the major factors that affect the behavior of debris flows is essential prior to its application this paper thus lays theoretical ground for extensive further studies of such factors

independent active microplate tectonics of northeast asia from gps velocities and block modeling 1 independent okhotsk and amurian microplate motions are tested using velocities from 123 gps sites 80 from within the proposed okh and amu plate boundaries used to constrain the plate kinematics of northeast asia a block modeling approach is used to incorporate both rigid block rotation and near boundary elastic strain accumulation effects in a formal inversion of the gps velocities models include scenarios with and without independent okh and amu plate motion our modeling favors scenarios with independent okh and amu motion based on the application of f test statistics the independent okh plate rotates 0 231 deg myr clockwise with respect to north america about a pole located north of sakhalin the modeled amu plate rotates 0 298 deg myr counterclockwise with respect to nam about a pole located west of the magadan region the plate motion parameters of the independent plates are consistent with the kinematics inferred from earthquake focal mechanism solutions along their boundaries

an empirical approach to studying debris flows implications for planetary modeling studies 1 high resolution images acquired by the mars global survey mars orbiter camera show gullies on the walls of impact craters and valley systems on mars depositional aprons associated with these gullies have been interpreted by malin and edgett 2000 to be characteristic of debris flow and to indicate the presence of sources of liquid water at shallow depths below the martian surface by focusing on a terrestrial debris flow we test the application of chezy type modeling to provide more direct estimates of the dynamics of proposed debris flows on mars traditionally planetary scientists constrained by available remotely sensed data have used a range of flow models to gain insights from deposits into the behavior and rheologic nature of features such as lava flows debris flows and gravity driven flows on the basis of these model results broad interpretations of the physics governing flows of granular materials have been tempting based on limited field derived data this study tests and validates the extent to which the absolute value and relative variations of empirical parameters derived from the chezy type models describe the behavior of the general s slide debris flow 38 24 n 78 23 w in madison county virginia the results indicate that extreme caution must be taken when interpreting model results for turbulent flows of granular materials we obtained high precision topographic profiles superelevation data sedimentary facies and sedimentary textural properties over the debris flow this study focuses on the empirical parameter c whose value gauges energy dissipation in a flow thereby called flow resistance using field observations both variations and absolute values of c along the debris flow have been computed using two approaches 1 assuming constant volumetric flow rate q where only topography and high resolution images are required to compute channel dimensions and 2 a variable q calculated using field derived data assuming near newtonian flow conditions in the debris flow estimated values of c range from 0 035 to 0 099 when q is fixed c decreases as a function of distance downstream when q varies and c is computed from field derived flow speeds its value tends to increase downstream slightly these opposite results have been compared to the field observations to determine which best describes the behavior of the flow the variations in c downstream obtained using the flow speeds are most consistent with the geomorphic evidence for erosion of material by the debris flow and the presence of bends in the channel the average values of c 0 036 0 33 for the general s slide have been compared with computed c values for newtonian and near newtonian flows to assess the rheology of the flow during emplacement our terrestrial study demonstrates that advances in understanding of the dynamics of debris flows on the mars depends on obtaining debris flow speeds in addition to channel topography and flow thickness rather than just on channel topography flow thickness and the assumption that q is constant mars orbiter camera moc and mars observer laser altimeter mola data can be used to derive channel topography flow thickness and possibly flow speeds such data will provide more direct estimates of the dynamics of debris flows on mars than are currently available

ground penetrating radar investigation of active faults along the dead sea transform and implications for seismic hazards within the city of aqaba jordan abstract ground penetrating radar gpr was used in an effort to locate a major active fault that traverses aqaba city jordan measurements over an exposed trenched cross fault outside of the city identify a radar signature consisting of linear events and horizontal offset flexured reflectors both showing a geometric correlation with two known faults at a control site the asymmetric linear events are consistent with dipping planar reflectors matching the known direction of dip of the faults however other observations regarding this radar signature render the mechanism generating these events more complex and uncertain gpr measurements in aqaba city were limited to vacant lots seven gpr profiles were conducted approximately perpendicular to the assumed strike of the fault zone based on regional geological evidence a radar response very similar to that obtained over the cross fault was observed on five of the profiles in aqaba city although the response is weaker than that obtained at the control site the positions of the identified responses form a near straight line with a strike of 45 although subsurface verification of the fault by trenching within the city is needed the geophysical evidence for fault zone location is strong the location of the interpreted fault zone relative to emergency services military bases commercial properties and residential areas is defined to within a few meters this study has significant implications for seismic hazard analysis in this tectonically active and heavily populated region

which fractures are imaged with ground penetrating radar results from an experiment in the aspo hardrock laboratory sweden abstract identifying fractures in the subsurface is crucial for many geomechanical and hydrogeological applications here we assess the ability of the ground penetrating radar gpr method to image open fractures with sub mm apertures in the context of future deep disposal of radioactive waste gpr experiments were conducted in a tunnel located 410 m below sea level within the aspo hard rock laboratory sweden using 3 d surface based acquisitions 3 4 m 19 m with 160 mhz 450 mhz and 750 mhz antennas the nature of 17 identified gpr reflections was analyzed by means of three new boreholes bh1 bh3 9 9 5 m deep out of 21 injection and outflow tests in packed off 1 m sections only five provided responses above the detection threshold with the maximum transmissivity reaching 7 0 10 10 m2 s most gpr reflections are situated in these permeable regions and their characteristics agree well with core and optical televiewer data a 3 d statistical fracture model deduced from fracture traces on neighboring tunnel walls show that the gpr data mainly identify fractures with dips between 0 and 25 since the gpr data are mostly sensitive to open fractures we deduce that the surface gpr method can identify 80 of open sub horizontal fractures we also find that the scaling of gpr fractures in the range of 1 10 m2 agrees well with the statistical model distribution indicating that fracture lengths are preserved by the gpr imaging no measurement bias our results suggests that surface gpr carries the resolution needed to identify the most permeable sub horizontal fractures even in very low permeability formations thereby suggesting that surface gpr could play an important role in geotechnical workflows for instance for industrial scale siting of waste canisters below tunnel floors in nuclear waste repositories

small scale spatial structure and long term variability of near bottom layers in the hebble area abstract analysis of 4 years of deep ocean measurements in the hebble area indicate significant mean spatial differences in bottom layer velocities as well as temperatures associated with the cold filament the data indicate that the cold filament core potential temperature less than 1 80 c is order 7 km wide comparable to the rossby radius of deformation and its location can fluctuate across slope in a range about four times larger than its instantaneous width the signature of the variability of the gulf stream is evident in the bottom layer for periods of 90 days the eddies range and 1 year associated with a seasonal shift in the gulf stream position may be a small out of phase across slope shift in the cold filament location the observed spatial structure in the velocity field may be due to thermal wind effects associated with the inclination of the transition region above the cold filament core

visualization of active faults using geometric attributes of 3d gpr data an example from the alpine fault zone new zealand three dimensional ground penetrating radar gpr data are routinely acquired for diverse geologic hydrogeologic archeological and civil engineering purposes interpretations of these dataareinvariablybasedonsubjectiveanalysesofreflectionpatterns such analyses are heavily dependent on interpreter expertiseandexperience usingdataacquiredacrossgravelunitsoverlyingthealpinefaultzoneinnewzealand wedemonstratethe utilityofvariousgeometricattributesinreducingthesubjectivity of3dgprdataanalysis weuseacoherence basedtechniqueto compute the coherency azimuth and dip attributes and a graylevel co occurrence matrixglcmmethod to compute the texture basedenergy entropy homogeneity andcontrastattributes a selection of the gpr attribute volumes allows us to highlight key aspects of the fault zone and observe important features not apparent in the standard images this selection also provides information that improves our understanding of gravel deposition andtectonicstructuresatthestudysite anewdepositional structuralmodellargelybasedontheresultsofouranalysisofgprattributes includes four distinct gravel units deposited in three phases and a well defined fault trace this fault trace coincides with a zone of stratal disruption and shearing bound on one side by upward tilted to synclinally folded stratified gravels and on the other side by moderately dipping stratified alluvial fan gravelsthatcouldhavebeenaffectedbylateralfaultdrag whenused in tandem the coherence and texture based attribute volumes can significantly improve the efficiency and quality of 3d gpr interpretation especially for complex data collected across activefaultzones

carbonate debris flows cow head group western newfoundland abstract the cow head group is an allochthonous cambro ordovician sequence of deep water limestone conglomerates mudstones to grainstones minor quartz sandstones siltstones and shales platy clast conglomerates and boulder rich megaconglomerates as much as 100 m thick exhibit features similar to those described for subaerial debris flows that is flat sharp bases with only minor evidence for erosion poorly developed clast fabric with tilting of platy clasts at right angles to the flow direction boulders floating within flows or projecting above the tops of flows irregular flow tops indicating primary relief above the sea floor and tapered flow margins snouts snout geometry and the extent of boulder projection both allow calculation of debris static strength these results combined with measured flow thickness permit calculation of minimum and maximum paleoslope gradients original debris static strengths were in the range of 103 to 105 dynes cm2 similar to the observed range in subaerial flows calculations yield bottom gradients of l l 8 but independent field data suggest that the paleoslope dip was on the order of only a few degrees this constraint suggests that debris strength was substantially reduced during flow probably by excess pore fluid pressures thus permitting flow on very gentle slopes the paleoslope orientations used in this study are substantially different from those previously published by hubert et at 1977

on traction carpet sedimentation traction carpets are highly concentrated bedload layers that are developed beneath and driven by turbulent overlying flows they have a convex up velocity profile and comprise a lower frictional and an upper collisional region the frictional region having a particle concentration more than 80 of the packed bed is characterized by nearly continuous grain contacts low strain rate and hampered grain segregation on the other hand the collisional region has a particle concentration between 15 and 80 of the packed bed and is characterized by active grain collisions and higher strain rate deposition from the traction carpets occurs via progressive aggradation of the bed rather than via en masse freezing while the downward grain flux from the overlying flow maintains them the thickness of a traction carpet stratum is therefore determined by the cumulative amount of sediment settled during the lifespan of a traction carpet and can be much larger than the thickness of a moving traction carpet inverse grading can be produced in the collisional region by the vertical gradient of dispersive pressure which is related to nonuniform distribution of particles when a thick frictional region develops however the inverse size distribution in the collisional region is poorly recorded in the deposits depositional features of traction carpet strata are therefore determined by the duration of a traction carpet and the thickness ratio of collisional to frictional regions the thickness ratio is further controlled by the applied shear stress sediment fallout rate and grain size generally a collisional region is better developed beneath a highly competent and coarse grained gravelly flow whereas a thick frictional region is developed beneath a heavily sediment laden fine grained sandy flow this explains the more common occurrence of inverse grading in coarse grained deposits

from decades to epochs spanning the gap between geodesy and structural geology of active mountain belts geodetic data from the global navigation satellite system gnss and from satellite interferometric radar insar are revolutionizing how we look at instantaneous tectonic deformation but the significance for long term finite strain in orogenic belts is less clear we review two different ways of analyzing geodetic data velocity gradient fields from which one can extract strain dilatation and rotation rate and elastic block modeling which assumes that deformation is not continuous but occurs primarily on networks of interconnected faults separating quasi rigid blocks these methods are complementary velocity gradients are purely kinematic and yield information about regional deformation the calculation does not take into account either faults or rigid blocks but where gnss data are dense enough active fault zones and stable blocks emerge naturally in the solution block modeling integrates known structural geometry with idealized earthquake cycle models to predict slip rates on active faults future technological advances should overcome many of today s uncertainties and provide rich new data to mine by providing denser more uniform and temporally continuous observations

integration of gpr with stratigraphic and lidar data to investigate behind the outcrop 3d geometry of a tidal channel reservoir analog upper ferron sandstone utah highly compartmentalized reservoirs are commonly attributed to heterogeneous facies as well as vertical horizontal stratigraphic trends associated with depositional cycles detailed information on stratigraphic heterogeneity is essential to fully exploit a reservoir subseismic scale reservoir stratigraphy can be investigated in outcrop by integrating multiple high resolution sedimentological data lidar light detection and ranging data and gpr ground penetrating radar data this combination of different data sets can help to characterize ancient tidal channels exposed in outcrops which are considered to be heterogeneous compartmentalized sandstone reservoir analogs this multidisciplinary approach not only attempts to describe rarely seen cretaceous tidal channel deposits at the dry wash outcrop figure 1 in three dimensions but it also demonstrates how the different types of data can be integrated to better understand ancient complex shallow marine depositional systems

controls and evolution of fan delta systems in the miocene pohang basin se korea abstract the miocene pohang basin southeastern korea occurs in the eastern part of the ne sw trending yangsan fault which has experienced right lateral strike slip deformation since the eocene during the miocene however the strike slip movement was negligible and instead was under extensional regime large scale drainage systems were developed at the junction between the strike slip zone and the oblique transfer faults acting as major sources for coarse grained sediments high rate of sediment supply and rapid subsidence of the hanging wall resulted in the progradation of large scale gilbert type fan deltas doumsan duksung and gohyun systems which all show a radial distributional pattern along the steeply inclined footwall scarps created by ne sw trending faults the drainage systems were relatively small here low rate of sediment supply formed scree apron type malgol and yugye systems and steep faced slope type maesan system fan deltas based on variations in sedimentary facies and distribution architecture and overlapping patterns the fan delta systems in the pohang basin can be divided into four stages of evolution during the early stage early miocene alluvial fans prograded into shallow marine setting in the doumsan and duksung systems high rate of sediment supply and rapid rise of relative sea level resulted in the transformation of shoal water type to gilbert type foresets in the malgol and maesan systems rapid sea level rise accompanied with low rate of sediment supply caused transformation of alluvial fans to scree apron type and steep faced slope type fan deltas respectively in the second stage subsidence of the hanging wall formed large scale truncation surfaces in the doumsan and duksung fan deltas coarse grained sediments were continuously supplied in the doumsan system whereas only fine grained sediments were deposited in the duksung system in the malgol system sediment supply was almost terminated in this stage in the third stage middle miocene sediment supply rate of the doumsan fan delta decreased abruptly and the system was overlain by fine grained gilbert type deposits the duksung fan delta was overlain by the maesan and gohyun systems the maesan system prograded further basinward during the last stage late miocene sediment supply of the doumsan and maesan systems was also terminated and the entire basin was draped by fine grained biogenic materials mainly diatoms

debris flow and hyperconcentrated flood flow deposits in an alluvial fan northwestern part of the cretaceous yongdong basin central korea abstract the alluvial fan deposits in the cretaceous yongdong basin korea consist of conglomerates with a muddy or sandy matrix and sandstones with thick or thin laminations the conglomerates and sandstones occur commonly in couplets constituting apparently single sedimentation units facies transitions in the deposits can be summed up in a tripartite facies sequence 1 a clast supported conglomerate with a muddy or sandy matrix and parallel clast alignment facies a and b 2 a matrix supported coarse tail normally graded conglomerate with random clast orientation facies c and thickly stratified pebbly sandstone facies d and 3 laminated sandstone facies e the clast supported conglomerate is interpreted as deposits of debris flows dominated by frictional grain interactions development of pervasive parallel clast alignment lacking large floating clasts and inverse grading suggests deposition via incremental aggradation rather than en masse freezing the matrix supported conglomerate an

finding the buried record of past earthquakes with gpr based palaeoseismology a case study on the hope fault new zealand in places where sedimentation and erosion compete at fast rates part of the record of past earthquakes on faults may be buried hence hidden in the first few metres below the surface we developed a novel form of palaeoseismology of geophysical type based on the use of a dense pseudo 3 d ground penetrating radar gpr survey to investigate such possible buried earthquake traces on a long fast slipping strike slip fault hope fault new zealand at a site terako where marked alluvial conditions prevail we first used lidar data to analyse the ground surface morphology of the 2 km2 site at the greatest resolution nineteen morphological markers were observed mainly alluvial terrace risers and small stream channels that are all dextrally offset by the fault by amounts ranging between 3 and 200 m the measurements document about 10 past earthquake slip events with a mean coseismic slip of 3 3 1 m with the most recent earthquake event having a slip of 3 0 5 m we then investigated a detailed area of the site 400 x 600 m2 with pseudo 3 d gpr we measured 56 similar to 400 m long 510 m spaced gpr profiles 250 mhz parallel to the fault and evenly distributed on either side the analysis revealed the existence of a palaeosurface buried at about 3 m depth corresponding to the top of alluvial terraces of different ages that buried surface is incised by a dense network of stream channels that are all dextrally offset by the fault we measured 48 lateral offsets in the buried channel network more than twice than at the surface these offsets range between 6 and 108 m as observed at the surface yet provide a more continuous record of the fault slip the similarity of the successive slip increments suggests a slip per event averaging 4 4 1 m fairly similar to that estimated from surface data from the total surface and buried 67 offset collection we infer that a minimum of 30 large earthquakes have broken the hope fault at the terako site in the last about 67 kyr with an average coseismic slip of 3 2 1 m a minimum average recurrence time of about 200 yr and a magnitude of at least mw 7 07 4 our study therefore confirms that part of the record of past earthquakes may indeed reside in the first few metres below the surface where it may be explored with geophysical gpr based palaeoseismology developing such a new palaeoseismological tool should provide rich information that may complement surface observations and help to document the past earthquakes on faults

geodetic constraints on san francisco bay area fault slip rates and potential seismogenic asperities on the partially creeping hayward fault 1 the hayward fault in the san francisco bay area sfba is sometimes considered unusual among continental faults for exhibiting significant aseismic creep during the interseismic phase of the seismic cycle while also generating sufficient elastic strain to produce major earthquakes imaging the spatial variation in interseismic fault creep on the hayward fault is complicated because of the interseismic strain accumulation associated with nearby faults in the sfba where the relative motion between the pacific plate and the sierra block is partitioned across closely spaced subparallel faults to estimate spatially variable creep on the hayward fault we interpret geodetic observations with a three dimensional kinematically consistent block model of the sfba fault system resolution tests reveal that creep rate variations with a length scale of 15 km are poorly resolved below 7 km depth in addition creep at depth may be sensitive to assumptions about the kinematic consistency of fault slip rate models differential microplate motions result in a slip rate of 6 7 0 8 mm yr on the hayward fault and we image along strike variations in slip deficit rate at 15 km length scales shallower than 7 km depth similar to previous studies we identify a strongly coupled asperity with a slip deficit rate of up to 4 mm yr on the central hayward fault that is spatially correlated with the mapped surface trace of the 1868 mw 6 9 7 0 hayward earthquake and adjacent to gabbroic fault surfaces

storms and flow reversals at the hebble site abstract we examine a 20 month long abyssal current meter record obtained from the hebble site about 40 27 n 62 22 w as expected the westward flowing abyssal western boundary current described by richardson et al 1981 and weatherly and kelley 1982 generally passes over this site we call this current the cold filament current cfc and conclude that it is appreciably stronger than suggested by weatherly and kelley 1984 15 cm s 1 as compared to 10 cm s 1 after comparing the abyssal current record with charts showing the surface location of the gulf stream and rings we conclude that the majority of abyssal storms at the hebble site are due to the presence of the cfc passing by and the absence of a meander or ring overhead the presence of a ring or meander overhead apparently results in the cfc being displaced out of the hebble site as suggested by kelley 1984 at such times the near bottom flow appears to respond to the barotropic component of the overlying ring or meander

fluvial geomorphology and neotectonic activity based on field and gpr data katrol hill range kachchh western india abstract the largely rocky and rugged landscape of the katrol hill range composed of mesozoic rocks and structurally controlled occurrences of quaternary sediments is delimited to the north by north facing range front scarps of the seismically active e w trending katrol hill fault khf the landscape and drainage characteristics of the katrol hill range are documented together with ground penetrating radar gpr investigations along the khf to delineate its nature for understanding neotectonic activity in the contemporary tectonic setting the overall geomorphology is controlled by the south oriented tilt block structure of the range indicated by its pronounced influence on the morphology and drainage network the drainage comprises north flowing and south flowing rivers with the drainage divide located close to the northern edge of the range which also marks the highest topographic elevations the narrow zone between the crest line and the drainage divide has been identified as the zone of gorges where gorges and deeply incised fluvial valleys have been formed within quaternary sediments by the various north flowing streams the quaternary sediments consist of bouldery colluvial deposits in front of the range front scarps valley fill miliolites and alluvial deposits of late pleistocene age within the back valleys and scarp derived colluvium forming the youngest deposit based on the geomorphic and stratigraphic evidence three major phases of quaternary tectonic uplift in the katrol hill range are inferred the oldest pre miliolite phase middle pleistocene was followed by a prominent phase of fluvial incision with formation of gorges during early holocene and then by the last one during late holocene continuing at present uplift of the range occurred in well marked phases during the quaternary in response to differential uplift along the khf under an overall compressive stress regime gpr investigations at selected sites show that the khf is a steep south dipping reverse fault near the surface which becomes vertical at depth this suggests neotectonic reactivation of the khf under a compressive stress regime responsible for active southward tilting of the katrol hill range

gpr derived architecture of a lahar generated fan at cotopaxi volcano ecuador the internal geometry of volcaniclastic fans produced by aggradation during lahar events is difficult to examine in modern settings because of the frequent lack of three dimensional exposures this makes it challenging to i reconstruct the spatial and temporal evolution of such fans and ii interpret observed facies stratigraphy in the context of lahar flow dynamics from proximal to distal fan reaches this research therefore presents the results of a ground penetrating radar gpr survey of the rumipamba fan at the mouth of the burrohuaycu quebrada on the southwestern flank of cotopaxi volcano a survey grid consisting of 50 individual gpr profiles representing a total length of 19 4 km was constructed covering most of the 4 km2 large fan surface all gpr profiles were collected using a pulseekko 100 with a 400 v transmitter fan sediments consist of sandy and gravelly lahar deposits alternating with volcanic fallout including ash and pumice lapilli at times reworked by fluvial processes deposits could be ground truthed to a depth of 3 m whereas gpr penetration depth reaches 15 m data interpretation was based on classification into 15 distinct radar facies characterized by the nature of their bounding surfaces and or internal features cross referenced where possible with shallow exposures three main facies were identified parallel irregular and clinoform erosional contacts were distinguished from aggradational ones vertical channel fill and lateral accretion flow parallel versus flow transverse and proximal distal variations in deposit architecture were featured the results of this study confirm the existence of two major channel systems in the northern and southern extremities of the fan and the more recent formation of a smaller central fan channel system deposit architecture is complex and facies chronologies illustrate that lahars have affected the entire survey area

time lapse imaging of saline tracer transport in fractured rock using difference attenuation radar tomography 1 accurate characterization of fractured rock aquifer heterogeneity remains one of the most challenging and important problems in groundwater hydrology we demonstrate a promising strategy to identify preferential flow paths in fractured rock using a combination of geophysical monitoring and conventional hydrogeologic tests cross well differenceattenuation ground penetrating radar was used to monitor saline tracer migration in an experiment at the u s geological survey fractured rock hydrology research site in grafton county new hampshire radar data sets were collected every 10 min in three adjoining planes for 5 hours during each of 12 tracer tests an innovative inversion method accounts for data acquisition times and temporal changes in attenuation during data collection the inverse algorithm minimizes a combination of two functions the first is the sum of weighted squared data residuals second is a measure of solution complexity based on an a priori space time covariance function subject to constraints that limit radarattenuation changes to regions of the tomograms traversed by high difference attenuation ray paths the time series of tomograms indicate relative tracer concentrations and tracer arrival times in the image planes from these we infer the presence and location of a preferential flow path within a previously identified zone of transmissive fractures these results provide new insights into solute channeling and the nature of aquifer heterogeneity at the site index terms 0910 exploration geophysics data processing 0915 exploration geophysics downhole methods 1829 hydrology groundwater hydrology 1832 hydrology groundwater transport 1894 hydrology instruments and techniques keywords radar tomography fractured rock ground penetrating radar geophysics hydrogeophysics

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

ground penetrating radar survey of a prehistoric site in southern italy abstract in this paper we present and discuss the results of a ground penetrating radar gpr study carried out in an area of southern italy where a karst cave with prehistoric remains was found the aim of the study involved the imaging of the subsurface stratigraphy both inside and outside the cave in order to assist archaeologists in an excavation programme the survey grid comprised 18 intersecting gpr profiles problems associated with the use of the gpr within a cave environment are highlighted and the data processing sequence designed to extract useful geo archaeological signatures is described interpretation of the radar sections was controlled by the excavation of two trenches inside and outside the cave allowing detailed outlining the complex stratigraphy and the reconstruction of palaeolithic and neolithic subsurface horizons

use of ground penetrating radar for assessment of potential sinkhole conditions an example from ghor al haditha area jordan sinkholes are near surface indicators of active karst features at depth such as cavities conduits and solutionally enlarged fractures this study tests the usefulness of ground penetrating radar gpr to identify and locate buried sinkholes as a means of interpreting the existence of these subsurface hydraulically active karst features gpr survey was made at the ghor al haditha area west of the jordan dstf in the jordan valley escarpment at the eastern dead sea shoreline gpr profiles 100 mhz made along the eastern dead sea shoreline showed a trough like pattern of radar reflections outlining a series of possible filled sinkholes this feature is about 38 m wide and about 12 m deep its width is consistent with the width of the feature obtained from the topographic map of the area the gpr survey suggests that this feature has been filled with relatively dense and resistive materials this structure lies almost directly above a major water bearing zone

subaqueous density flow processes and deposits of an island volcano landslide stromboli island italy stromboli is a 3000 m high island volcano rising to 900 m above sea level it is the most active volcano of the aeolian archipelago in the tyrrhenian sea italy major large volume 1 km 3 sector collapses four occurring in the last 13 kyr have played an important role in shaping the north western flank sciara del fuoco of the volcano potentially generating a high risk tsunami hazard for the aeolian islands and the italian coast however smaller volume partial collapses of the sciara del fuoco have been shown to be more frequent tsunami generating events one such event occurred on 30 december 2002 when a partial collapse of the north western flank of the island took place the resulting landslide generated 10 m high tsunami waves that impacted the island multibeam bathymetry side scan sonar imaging and visual observations reveal that the landslide deposited 25 to 30 10 6 m 3 of sediment on the submerged slope offshore from the sciara del fuoco two contiguous main deposit facies are recognized i a chaotic coarse grained metre sized to centimetre sized clasts deposit and ii a sand deposit containing a lower cross bedded sand layer and an upper structureless pebbly sand bed capped by sea floor ripple bedforms the sand facies develops adjacent to and partially overlying the coarse deposits characteristics of the deposits suggest that they were derived from cohesionless sandy matrix density flows flow rheology and dynamics led to the segregation of the density flow into sand rich and clast rich regions a range of density flow transitions both in space and in time caused principally by particle concentration and grain size partitioning within cohesionless parent flows was identified in the deposits of this relatively small scale submarine landslide event

aeolian construction and alluvial dismantling of a fault bounded intracontinental aeolian dune field teruel basin spain a continental perspective on late pliocene climate change and variability an aeolian dune field migrating to the east encroached on the toes of alluvial fans in the teruel basin eastern spain during a short interval in the late pliocene ca 2 9 to 2 6 ma when northern hemisphere glaciation and strong glacial interglacial cycles began preservation of the dune field was controlled by syn sedimentary activity of a normal fault ephemeral water discharge eroded aeolian sands and formed v shaped channels in which aeolian sandstone blocks accumulated the incorporation of loose aeolian sand in wadi waters modified the sediment water ratio changing the physical properties of the flows as they penetrated the aeolian dune field the erosion and cover of aeolian dune foresets by sheetflood deposits suggest that dune damming caused the intermittent ponding of water behind the dunes and its flashy release the arid climate in the late pliocene western mediterranean realm favoured the transport of windblown sediments from northern africa and western mediterranean land masses into the mediterranean the formation of the studied aeolian dune field 2 9 to 2 6 ma and possibly others for example the atacama namib and sahara deserts correlates with a strong increase of the influence of obliquity which can be attributed to the combination of a regional expression related to the reduced effect of precession due to a minimum in the long period 2 3 ma eccentricity cycle and a remote expression of the onset of the northern hemisphere glaciation

coarse grained debris flow deposits in the miocene fan deltas se korea a scaling analysis abstract the viscoplastic and inertial grain flow models have been widely used as tools for description and interpretation of ancient debris flow deposits providing a basis to estimate yield strength viscosity cohesion and internal friction angle recent studies suggest however that a debris flow is an intimate mixture of solid and fluid in which a number of momentum transfer mechanisms operate it is therefore necessary to evaluate the relative importance of different momentum transport processes to properly describe a debris flow scaling analysis may be useful to this end using the bagnold number the ratio of inertial grain stress to viscous shear stress savage number the ratio of inertial grain stress to shear stress borne by sustained grain contacts friction number the ratio of frictional shear stress to viscous shear stress and darcy number the ratio of grain fluid interaction stress to inertial grain stress scaling analyses of miocene gravelly debris flow deposits in korea suggest that different types of debris flows can be better distinguished by the analyses providing some implications for debris flow processes

properties of debris flow deposits and source materials compared implications for debris flow characterization in the alps debris flow deposits generally contain 5 clay size particles and the role of the surface charged 2 mu m particles is often neglected although these particles may have a significant impact on the rheological properties of the interstitial fluid the objective of this study was to compare debris flow deposits and parent materials from two neighbouring catchments of the swiss alps with special emphasis on the colloidal constituents the catchments are small in area 4 km 2 2 5 km long similar in morphology but different in geology the average slopes are 35 40 the catchments were monitored for debris flow events and mapped for surface aspect and erosion activity debris flow deposits and parent materials were sampled the clay and silt fractions extracted and the bulk density 2 mm fraction bulk density particle size distribution chemical composition cation exchange capacity cec and mineralogy analysed the results show that the deposits are similar to the parent screes in terms of chemical composition but differ in terms of i particle size distribution and ii mineralogy reactivity and density of the 2 mm fraction in this fraction compared with the parent materials the deposits show dense materials enriched in coarse monocrystalline particles of which the smallest and more reactive particles were leached the results suggest that deposit samples should not be considered as representative of source or flow materials particularly with respect to their physical properties

partitioning of localized and diffuse deformation in the tibetan plateau from joint inversions of geologic and geodetic observations abstract the spatial complexity of continental deformation in the greater tibetan plateau region can be defined as the extent to which relative motion of the indian and asian plates is partitioned between localized slip on major faults and distributed deformation potency rates provide a quantitative metric for determining the magnitudes of diffuse and on fault crustal deformation which are proportional to strain rates within crustal micro plates and fault slip rates respectively we simultaneously estimate micro plate rotation rates interseismic elastic strain accumulation fault slip rates on major structures and strain rates within 24 tectonic micro plates inferred from active fault maps in the greater tibetan plateau region using quasi static block models constrained by interseismic surface velocities at 731 gps sites and 9 holocene late quaternary geologic fault slip rates the joint geodetic geologic inversion indicates that geologic slip rates are kinematically consistent with differential micro plate motions estimated left lateral slip rates on the altyn tagh west central kunlun and xianshuihe faults are relatively homogeneous along strike 11 5 10 5 and 11 mm yr respectively while segmentation of the eastern kunlun fault by the intersecting elashan and riyueshan faults results in a decreased slip rate consistent with geologic observations the fraction of total potency rate associated with intrablock strain uncorrected for observational noise ranges from 0 27 in the himalayan range block to 0 91 in the aksai chin block monte carlo simulations are used to quantify the likelihood that internal deformation is statistically distinguishable from the uncertainties in geodetic velocities these simulations indicate that internal block deformation is statistically significant only within the himalayan range front where internal deformation accounts for id 0 11 of block potency rate budget west central plateau id 0 68 ganzi yushu xianshuihe 0 58 burma 0 09 jiali 0 38 and aksai chin 0 68 blocks in the other 18 tectonic micro plates within the plateau region estimated internal block potency is not currently distinguishable from the expected contribution of observational noise to residual velocities of the total potency budget within the tibetan plateau 85 is taken up by slip on major faults with the remaining 15 accommodated by internal processes at sub block scale distinguishable from observational noise the localization of the majority of plate boundary activity is also supported by the spatial distribution of modern and historical crustal earthquakes sixty seven percent of the total moment released by earthquakes in the cmt catalog and 90 of historical moment since 1900 have been released within 25 km of the major faults included in the block model representing only 12 of the characteristic half block length scale of 215 km the localization of deformation inferred from geologic geodetic and seismic observations suggests that forces applied to tectonic micro plates drive fault system activity at the india asia collision zone over decadal to quaternary time scales

depositional processes in large scale debris flow experiments this study examines the depositional process and characteristics of deposits of large scale experimental debris flows to 15 m3 composed of mixtures of gravel to 32 mm sand and mud the experiments were performed using a 95 m long 2 m wide debris flow flume that slopes 31 following release experimental debris flows invariably developed numerous shallow 10 cm deep surges sediment transported by surges accumulated abruptly on a 3 runout slope at the mouth of the flume deposits developed in a complex manner through a combination of shoving forward and shouldering aside previously deposited debris and through progressive vertical accretion progressive accretion by the experimental flows is contrary to commonly assumed en masse sedimentation by debris flows despite progressive sediment emplacement deposits were composed of unstratified accumulations of generally unsorted debris hence massively textured poorly sorted debris flow deposits are not emplaced uniquely en masse the depositional

on the temporal variability of the surface gulf stream and near bottom flows long 3 4 years time series of the surface gulf stream position and near bottom flow south of nova scotia support earlier findings of a barotropic semimonthly periodicity in the region a bimodal gulf stream path downstream of the new england seamount chain and a seasonal shift in the gulf stream position new results are 1 a marked reduction of the meridional shifts of the surface gulf stream when it is in its north position mode 2 the semimonthly periodicity seeming to be related at times to the mf tide the most energetic long period tide and 3 an energetic highly coherent but out of phase motion with a near 40 day period in the surface gulf stream position and near bottom flow

evolution of debris flow properties and physical interactions in debris flow mixtures in the wenchuan earthquake zone abstract the 2008 wenchuan earthquake triggered an exceptional number of landslides the large amount of loose landslide materials on the steep terrains can easily turn into debris flows by heavy rainfall during the wet seasons from 2008 to 2011 five destructive debris flows occurred repeatedly in yingxiu the study area near the epicenter this paper presents the evolution of debris flow properties and physical interactions in the debris flow mixtures in the past few years seven dimensionless numbers are used to describe the physical interactions the evolution of the physical interactions over time was influenced by changes in debris flow compositions which in turn affected the runout characteristics of the debris flows significantly grain contact friction was the most important physical interaction for the five debris flows in the study area with gradual loss of fine particles over time the viscosity of the debris flow mixtures became lower and lower leading to a change from the dominance of viscous shear over solid fluid interactions and inertial grain collision to the dominance of solid fluid interactions and inertial grain collision over viscous shear with inertial grain collision being more and more important the flow resistance of the debris flows increased the mobility of the future debris flows may become smaller and smaller

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

ground penetrating radar profiles over multiple steel tanks artifact removal through effective data processing this paper describes some ground penetrating radar gpr results to characterize steel tanks buried in the subsoil of an urban center tanks were installed in the first brazilian geophysical test site located at the institute of astronomy geophysics and atmospheric science iag of the university of sao paulo usp this paper also presents an effec tive procedure for removal of hyperbolic artifacts associated with gpr reflections between multiple steel tanks one hundred sixty five gpr profiles of 200 mhz 400 mhz and 500 mhz shielded bistatic antennae were measured the work was done in two distinct places on the geophysical test site of the iag usp in the city of sao paulo brazil and in an area formerly occupied by a truck cleaning refueling and maintenance facility located in oscoda northeastern michigan usa predictive deconvolution and kirchhoff migration were first used to improve vertical and lateral resolution to minimize the hyperbolic artifacts caused by reflections between tank