a phenomenological modelling of rocks based on the influence of damage initiation it is recognized that the stress induced damage impacts the progressive failure behavior of rocks a phenomenological model for the compressive failure of rocks is thus presented in this study the model addresses the progressive growth of damage that leads to the strength weakening on a macroscopic scale considering dramatic difference between uniaxial compression and tension strengths for rocks the admitted mises schleiche drucker prager strength criterion is adopted to characterize the damage initiation on this basis a two parameter weibull type probability function is used to define the strength distribution of representative volume elements followed by the use of damage variable for addressing the accumulated probability of failure the proposed damage variable essentially characterizes both the critical stress level of damage initiation and progressive damage evolution law detailed comparisons have been carried out between the predictions and experimental observations and issues related to the damage evolution are particularly addressed in addition the results further validate the proposed model considering damage initiation

mode of occupation of tabun cave mt carmel israel during the mousterian period a study of the sediments and phytoliths alternative modes of occupation of tabun cave during the deposition of the mousterian levels b and c have been proposed garrod bate 1937 excavations at the wady el mughara volume 1 oxford clarendon press interpreted the archaeological record of both levels as being indicative of domestic occupational activities jelinek et al 1973 palaeorient 1 151 183 proposed that the presence of articulated limb bones of dama mesopotamica in the level b sediments below the cave chimney indicated that the cave was used as a natural game trap they also noted that the white ash layers in level c extended across the whole cave and proposed that this was due to the burning of natural vegetation in the cave this study aims at clarifying the modes of occupation during these periods level b sediments closely resemble the terra rossa soil that is common in this region burning activity is inferred from charcoal fragments seen in thin sections a minor wood ash component is present based on the preponderance of phytoliths with a variable morphology as compared to those with a consistent morphology as well as phytoliths with shapes characteristic of those formed in wood and bark of local trees thus fires were produced in the cave during this period the cave may also have been used as a game trap level c is composed of multiple layers of brown black and white sediments micromorphology mineralogy and phytolith analyses all show that these layers are mixtures of terra rossa soil and ash with the latter being abundant in the white layers the phytoliths in these layers are derived almost entirely from wood and bark and not from grasses these observations are consistent with a domestic occupational mode 1999 academic press

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

coupled magma chamber inflation and sector collapse slip observed with synthetic aperture radar interferometry on mt etna volcano 1 volcanoes deform dynamically due to changes in both their magmatic system and instability of their edifice mt etna features vigorous and almost continuous eruptive activity from its summit craters and periodic flank eruptions even though its shape is that of a large stratovolcano its structure features two rift systems and a flank collapse structure similar to hawaiian shield volcanoes we analyze european remote sensing ers satellite differential interferometric synthetic aperture radar insar data 1993 1996 for mt etna spanning its quiescence from 1993 through the initiation of renewed eruptive activity in late 1995 we use synthetic aperture radar sar data from both ascending and descending ers satellite tracks comparison of independent interferograms covering the first 2 years of the inflationary period shows a pattern consistent with inflation of the volcano calculation of the tropospheric path delay based on meteorological data does not change this interpretation interferograms from late summer 1995 1996 show no significant deformation joint inversion of interferograms from ascending and descending satellite tracks require both inflation from a spheroidal magmatic source located beneath the summit at 5 km below sea level and displacement of the east flank of etna along a basal decollement both sources of deformation were contemporaneous within the resolution of our data and suggest that inflation of the central magma chamber acted to trigger slip of etna s eastern flank these results demonstrate that flank instability and recharge of a volcano s magma system must both be considered toward understanding how volcanoes work and in their hazard evaluation

a tethered interferometric synthetic aperture radar sar for a topographic mission analyzes a spaceborne interferometric synthetic aperture radar sar for high resolution topographic applications two physical antennas are vertically spaced and are carried along parallel paths by two different platforms connected by a tether tethered space systems have been proposed by several authors for different applications and a joint us italian program exists to deploy in 1992 a small satellite tethered satellite system from a space shuttle a system performance analysis is carried out considering a theoretical study and a numerical simulation by evaluating the tethered interferometric sar impulse response the height of various point scatterers is computed and an error budget is obtained results show that this system is capable of achieving a root mean square rms error in height measurement adequate for several applications

monitoring of slow ground deformation by ers radar interferometry on the vauvert salt mine france comparison with ground based measurement the differential sar interferometry dinsar technique has been applied to a test site near vauvert france to detect and monitor ground deformation this site corresponds to the location of an industrial exploitation of underground salt using the solution mining technique an area of subsidence has been observed using in situ measurements despite conditions unfavorable for insar because of the vegetal cover we show that radar remote sensing observations provide valuable information which substantially improves our knowledge of the phenomenon an adaptive phase filtering process has been used to improve the coherence level in particular our study shows that the geometry of the subsidence bowl is different to that previously assumed using ground based techniques only the size of the subsidence bowl 8 km is larger than expected this information will be useful for further modeling of the deformation and to improve the coverage of the in situ measurement networks it also shows that radar interferometry can be used for the long term monitoring of such sites and to predict potential environmental issues

on the optimization of interferometric sar for topographic mapping spaceborne synthetic aperture radar sar provides the possibility of producing topographic maps and cartographically corrected radar images using an interferometric method the technique requires two sar images of the same area gathered from slightly separated positions the interferometric baseline may be optimized to minimize the topographic altitude error the altitude error caused by the radar system and the topography is discussed the simulation of an interferometric measurement based on ers 1 sar parameters is presented it is found that the terrain topography has a significant effect on the height error which in many cases is more severe than baseline decorrelation

triaxial rheological property of sandstone under low confining pressure abstract the creep behavior of the rock mass in an anchoring section affects the control effect of the piles and the long term stability of the landslide and stabilizing slide structure the confining pressure of the anchoring section in the majiagou landslide in the three gorges reservoir is low to study the creep behavior of sandstone at low confining pressures the triaxial compression test and triaxial creep test are performed on the jurassic sandstone in the three gorges reservoir at three low confining pressures i e 3 0 mpa 5 0 mpa and 7 0 mpa the test results show three typical stages initial creep steady state creep and accelerated creep when the deviatoric stress is greater than the yield stress with the test results in this study an improved burgers model is developed to describe the initial creep and steady state creep furthermore a nonlinear newton component is added to the accelerated creep model the test data at all stages are well fitted by the developed creep models in this paper we take the critical stress that causes the steady state creep as the long term strength with the developed creep models the long term strength of the sandstone can be derived in comparison to the short term strength the internal friction angle and cohesion of the long term strength decrease by 15 and 13 respectively and the compression strength could be decreased by more than 50 thus in the design of stabilizing piles of the majiagou landslide the effect of rock creep on the strength should be considered

thick lava flows of karisimbi volcano rwanda insights from sir c interferometric topography we use a digital elevation model dem derived from interferometrically processed sir c radar data to estimate the thickness of massive trachyte lava flows on the east flank of karisimbi volcano rwanda the flows are as long as 12 km and average 40 60 m up to 140 m in thickness by calculating and subtracting a reference surface from the dem we derived a map of flow thickness which we used to calculate the volume up to 1 km3 for an individual flow and 1 8 km3 for all the identified flows and yield strength of several flows 23 124 kpa using the dem we estimated apparent viscosity based on the spacing of large folds 1 2 1012 to 5 5 1012 pa s for surface viscosity and 7 5 1010 to 5 2 1011 pa s for interior viscosity for a strain interval of 24 h we use shaded relief images of the dem to map basic flow structures such as channels shear zones and surface folds as well as flow boundaries the flow thickness map also proves invaluable in mapping flows where flow boundaries are indistinct and poorly expressed in the radar backscatter and shaded relief images

time dependent brittle creep in darley dale sandstone 1 the characterization of time dependent brittle rock deformation is fundamental to understanding the long term evolution and dynamics of the earth s crust the chemical influence of pore water promotes time dependent deformation through stress corrosion cracking that allows rocks to deform at stresses far below their short term failure strength here we report results from a study of time dependent brittle creep in water saturated samples of darley dale sandstone initial porosity 13 under triaxial stress conditions results from conventional creep experiments show that axial strain rate is heavily dependent on the applied differential stress a reduction of only 10 in differential stress results in a decrease in strain rate of more than two orders of magnitude however natural sample variability means that multiple experiments must be performed to yield consistent results hence we also demonstrate that the use of stress stepping creep experiments can successfully overcome this issue we have used the stress stepping technique to investigate the influence of confining pressure at effective confining pressures of 10 30 and 50 mpa while maintaining a constant 20 mpa pore fluid pressure our results demonstrate that the stress corrosion process appears to be significantly inhibited at higher effective pressures with the creep strain rate reduced by multiple orders of magnitude the influence of doubling the pore fluid pressure however while maintaining a constant effective confining pressure is shown to influence the rate of stress corrosion within the range expected from sample variability we discuss these results in the context of microstructural analysis acoustic emission hypocenter locations and fits to proposed macroscopic creep laws

time dependent cracking and brittle creep in crustal rocks a review abstract rock fracture under upper crustal conditions is driven not only by applied stresses but also by time dependent chemically activated subcritical cracking processes these subcritical processes are of great importance for the understanding of the mechanical behaviour of rocks over geological timescales a macroscopic manifestation of time dependency in the brittle field is the observation that rocks can deform and fail at constant applied stresses a phenomenon known as brittle creep here we review the available experimental evidence for brittle creep in crustal rocks and the various models developed to explain the observations laboratory experiments have shown that brittle creep occurs in all major rock types and that creep strain rates are extremely sensitive to the environmental conditions differential stress confining pressure temperature and pore fluid composition even small changes in any of these parameters produce order of magnitude changes in creep strain rates and times to failure three main classes of brittle creep model have been proposed to explain these observations phenomenological statistical and micromechanical statistical and micromechanical models explain qualitatively how the increasing influence of microcrack interactions and or the increasing accumulated damage produces the observed evolution of macroscopic deformation during brittle creep however no current model can predict quantitatively all of the observed features of brittle creep experimental data are limited by the timescale over which experiments are realistically feasible clearly an extension of the range of available laboratory data to lower strain rates and the development of new modelling approaches are needed to further improve our current understanding of time dependent brittle deformation in rocks

deformation characteristics of slate slopes associated with morphology and creep abstract this study investigated the deformation characteristics of consequent slate slopes in the region between cuifeng and wuling in taiwan onsite surveys terrain analysis and udec numerical models were used to describe the characteristics of gravity driven deformation under various conditions and identify the process of slate deformation as well as potential failure mechanisms our results demonstrate that valley erosion and slope toe soaking mechanisms play key roles in the deformation of slate and accelerate the weakening of slate material comparisons of material strength of rock and foliation the location of erosion gullies and the inclination of the foliation indicate that a reduction in the strength of rock material and foliation expanded the range of slate deformation the inclination of foliation is the most important factor in the deformation of slate and the location of erosion gullies has relatively little influence slate deformation was shown to begin in the tension zone at the cliff top wherein the slope body slips along the highly inclined foliation contributing to shear failure or composite failure near the eroded zone of weakness the phenomenon of foliation opening was widespread within the area of deformation enabling surface water and groundwater to seep in thereby accelerating failure in the slate deformation zone

phytolith transport in soil a field study using fluorescent labelling abstract soil phytoliths have been widely applied to reconstruct vegetational history to date however the transport behaviour of phytoliths in soil is poorly understood causing uncertainties in the interpretation of phytolith data the present study was therefore designed 1 to determine transport rates of phytoliths in loamy and sandy soils under field conditions and 2 to elucidate the effect of phytolith size and shape on their transport behaviour in sandy and loamy soils for this purpose we adopted a fluorescent labelling technique from veterinary science the phytoliths were extracted from common reed phragmites australis labelled with the fluorescent dye fluorescein isothiocyanate and applied to a loamy sand soil haplic cambisol and a silty loam soil stagnic luvisol in southern germany one year after application the soils were sampled to analyse phytolith distribution with soil depth the weighted mean transport distance of phytoliths after one year was 3 99 1 21 cm for the cambisol and 3 86 0 56 cm for the luvisol phytolith size significantly affected transport behaviour indicating a preferential translocation of small sized phytoliths our study provides direct evidence for a significant downward mobility of phytoliths in sandy and loamy soils under natural conditions this should be taken into account when using phytoliths as palaeoenvironmental tracers quantifying phytoliths in soil with fluorescent labelling makes it possible to identify artificially applied phytoliths without using the conventional extraction method

palaeoecological significance of palms at olduvai gorge tanzania based on phytolith remains abstract palms are among the most abundant diverse and economically important families of plants in tropical and subtropical regions of the world their number and diversity make them an important part of the ecosystem phytoliths are abundantly produced in palms mainly the spheroid echinate type and although their number decreases notably after their deposition in soils they remain stable for long periods of time palm phytoliths were recovered from sediments at hwkee on the eastern palaeolake margin of the olduvai basin during lowermost bed ii between tuffs if and iia 1 795 1 71 ma their abundance in trench 107 the only freshwater source recognised to date occurs in three stratigraphically consecutive layers the first one located immediately above the incision layer 40 cm above tuff if above these samples there are no palm phytoliths in the fossil record the identification of the type of palms represented will be useful for determining the landscape distribution and nature of hominin activities along the lake margin and alluvial fan of the central olduvai basin here we use morphometric analysis of spheroid echinate phytoliths from fossil and modern palms phoenix reclinata and hyphaene petersiana and their corresponding soils to determine if the differences are significant and can be confidently applied to the fossil samples fossil and modern soil samples were found to be very similar to each other but the spheroid echinates from the fossil soils were bigger than the modern soil samples either the palms from the samples were different or there is a strong bias towards preserving phytoliths from the smaller end of the range if this is the case then the implication would be that the fossil samples are the leaves and inflorescences of phoenix reclinata a wider variety of modern palms needs to be analysed

ash bones and guano a study of the minerals and phytoliths in the sediments of grotte xvi dordogne france abstract very few prehistoric cave deposits in western europe contain visible hearth remains even though there is abundant evidence of fire use by cave inhabitants grotte xvi dordogne france is exceptional in this respect in that it contains a most conspicuous layer couche c characterized by a series of brightly coloured bedded sediments the formation of couche c has previously been ascribed to the ash and charcoal produced by the cave s mousterian occupants burning mainly lichens the mousterian sedimentary layers below couche c and the upper palaeolithic sediments unconformably overlying couche c are quite different in texture and colour and show no visible evidence of ash deposits analyses of the minerals microstructures and phytoliths in couche c are consistent with the notion that these sediments were derived mainly from ash produced by burning wood and to a lesser extent grass the original calcite component of the ash has been diagenetically altered to carbonated apatite around the cave periphery and to even more insoluble phosphate minerals in the centre one such mineral newberyite most likely formed by the reaction between guano degradation products and the ash under these circumstances bone preservation is also affected the overlying upper palaeolithic sediments contain calcite one of these layers abb contains much more calcite than all the other layers as well as abundant phytoliths derived from wood and grass this layer also contained many artifacts and bones it is thus concluded that ash is a major component of layer abb even though it is not visible to the maked eye in the form of hearths

creep and time dependent damage in argillaceous rocks abstract this paper presents the results of laboratory tests on the time dependent behaviour of three rocks characterized by a high proportion of clay particles the viscosity of these sedimentary rocks was studied under different loading conditions in uniaxial compression static or cyclic creep tests and quasistatic tests low loading strain rate were performed across various orientations of fabric planes the quasistatic tests showed similarities in the mechanical response of these three argillaceous rocks a late phase of dilation and a linear development of volumetric deformation before the beginning of unstable crack propagation the development of secondary and tertiary creep phases during the creep tests highlighted the existence of a deviatoric stress threshold below which only primary creep is observed long term creep tests also showed that the volumetric variation is not constant during the development of viscoplastic deformations a microstructural analysis of thin sections extracted from specimens after the tests gave evidence of cataclastic and granular creep damage to the argillaceous matrix occurs and no cracks were observed in the quartz and carbonate grains this evidence was also demonstrated for tests with loading at a high strain rate finally this study highlights the significant viscoplasticity of argillaceous rocks the mechanical properties deteriorate rapidly when crack propagation becomes unstable and the viscoplastic strains seem to be due to clay particle slips known as granular creep

phase gradient approach to stacking interferograms the phase gradient approach is used to construct averages and differences of interferograms without phase unwrapping our objectives for change detection are to increase fringe clarity and decrease errors due to tropospheric and ionospheric delay by averaging many interferograms the standard approach requires phase unwrapping scaling the phase according to the ratio of the perpendicular baseline and finally forming the average or difference however unique phase unwrapping is usually not possible since the phase gradient due to topography is proportional to the perpendicular baseline phase unwrapping is unnecessary prior to averaging or differencing phase unwrapping may be needed to interpret the results but it is delayed until all of the largest topographic signals are removed we demonstrate the method by averaging and differencing six interferograms having a suite of perpendicular baselines ranging from 18 to 406 m cross spectral analysis of the difference between two tandem interferograms provides estimates of spatial resolution which are used to design prestack filters a wide range of perpendicular baselines provides the best topographic recovery in terms of accuracy and coverage outside of mountainous areas the topography has a relative accuracy of better than 2 m residual interferograms single interferogram minus stack have tilts across the unwrapped phase that are typically 50 mm in both range and azimuth reflecting both orbit error and atmospheric delay smaller scale waves with amplitudes of 15 mm are interpreted as atmospheric lee waves a few global positioning system gps control points within a frame could increase the precision to 20 mm for a single interferogram further improvements may be achieved by stacking residual interferograms

landslide activity as a geoindicator in italy significance and new perspectives from remote sensing landslide activity responds to rapid environmental changes and represents a relevant geoindicator in mountainous or hilly areas this paper discusses the socio economic relevance of landslide hazard in italy and the problems encountered in establishing relationships between landslide frequency climate and vegetation changes at different time scales landslides blocking a river channel have been carefully taken into account because they are usually characterized by high intensities with regard to the involved masses and movement velocities and their occurrences are often datable via radiocarbon dating this is due to the recovery of organic matter in the landslide dammed lakes for these reasons they can be considered important geoindicators in the wider category of slope failures the marked effects of the anthropogenic activity on slope instability processes in the last 50 years are discussed with reference to two case histories the chianti hills in tuscany and the cinque terre national park in liguria finally two novel techniques of remote sensing are proposed as tools for a systematic monitoring of slope instability at different time and spatial scales both techniques are based on the interferometric synthetic aperture radar sar technology and differ on the type of platform satellite and ground based used to acquire data

quantitative phytolith study of hearths from the natufian and middle palaeolithic levels of hayonim cave galilee israel abstract a study of the mineralogy and phytolith assemblages of hearths and their associated sediments in hayonim cave israel shows that wood ash is a major component of the sediments of both the natufian approximately 12 000 bp and the mousterian deposits approximately 100 to 250 000 bp interestingly phytolith analyses show that in the natufian deposits grasses are the second most abundant form of vegetation preserved whereas in the mousterian deposits leaves of dicotyledonous plants are the second most abundant form of vegetation preserved significant differences were repeatedly observed in phytolith assemblages from closely associated but different stratigraphic layers showing that vertical mixing of intact sediments is not intensive and that there was a diverse input of vegetation over relatively short time periods no consistent differences were observed in the mineralogy and the phytolith assemblages between hearths and their associated sediments both contain abundant ash components this study demonstrates that quantitative analyses of phytoliths together with mineralogical analyses can provide much information on the use of plants for fuel and other purposes by the cave occupants

integrated satellite interferometry tropospheric noise gps estimates and implications for interferometric synthetic aperture radar products interferometric synthetic aperture radar insar like other astronomic and space geodetic techniques is limited by the spatially and temporally variable delay of electromagnetic waves propagating through the neutral atmosphere statistical analysis of these variations from a wide variety of instruments reveals a power law dependence on frequency that is characteristic of elementary kolmogorov turbulence a statistical model for a major component of the delay fluctuations the wet component has previously been developed by treuhaft and lanyi 1987 for very long baseline interferometry a continuous global positioning system gps network is now in place in southern california that allows estimation of along with geodetic parameters the total delay due to the atmosphere above each site on a subhourly basis these measurements are shown to conform to the treuhaft and lanyi tl statistical model both temporally and spatially the tl statistical model is applied to the problem of insar and used to produce the covariance between two points separated in time and or space the error due to the atmospheric variations for sar products such as topography and surface deformation is calculated via propagation of errors there are two methods commonly cited to reduce the effect of atmospheric distortion in products from sar interferometry stacking and calibration stacking involves averaging independent interferograms to reduce the noise calibration involves removing part or all of the delay using data from an independent source such as total zenith delay estimates from continuous gps networks despite the relatively poor spatial density of surface measurements calibration can be used to reduce noise if the measurements are sufficiently accurate reduction in tropospheric noise increases with increasing number of measurement points and increasing accuracy up to a maximum of n where n is the number of points stacking and calibration are shown to be complementary and can be used simultaneously to reduce the noise to below that achievable by either method alone

influence of temperature on brittle creep in sandstones the characterization of time dependent brittle creep promoted by chemically active pore fluids is fundamental to our understanding of the long term evolution and dynamics of the earth s crust here we report results from a study of the influence of temperature on both short term strength and time dependent brittle creep in three sandstones under triaxial stress conditions we show that an increase in temperature from 20 degrees to 75 degrees c significantly enhances stress corrosion cracking in all three sandstones leading to 1 a systematic reduction in strength during constant strain rate experiments and 2 an increase by several orders of magnitude in brittle creep strain rates during stress stepping creep experiments we also show that a conventional creep experiment performed at 75 degrees c exhibits a qualitatively similar three stage brittle creep curve as that observed at ambient temperature extrapolation of our results suggests that temperature is likely to be the dominant influence on the evolution of creep strain rate with depth in the shallow crust citation heap m j p baud and p g meredith 2009 influence of temperature on brittle creep in sandstones geophys res lett 36 l19305 doi 10 1029 2009gl039373

scaling law of average failure rate and steady state rate in rocks the evolution properties in the steady stage of a rock specimen are reflective of the damage or weakening growth within and thus are used to determine whether an unstable transition occurs in this paper we report the experimental results for rock granite and marble specimens tested at room temperature and room humidity under three typical loading modes quasi static monotonic loading brittle creep and brittle creep relaxation deformed rock specimens in current experiments exhibit an apparent steady stage characterized by a nearly constant evolution rate which dominates the lifetime of the rock specimens the average failure rate presents a common power law relationship with the evolution rate in the steady stage although the exponent is different for different loading modes the results indicate that a lower ratio of the slope of the secondary stage with respect to the average rate of the entire lifetime implies a more brittle failure

environmental history of northwest australia based on phytolith analysis at carpenter s gap 1 examination of a phytolith assemblage from the archaeological site of carpenter s gap 1 provides an hitherto unrecognised source of vegetation history for the tropical savannah region of north western australia two predominant mechanisms contributed to the formation of the phytolith assemblage firstly the introduction of phytoliths in plant materials brought in by humans and secondly the introduction of phytoliths contained in faecal pellets deposited by animals separating the effects of both mechanisms enables local vegetation patterns and by inference climatic conditions to be reconstructed the period ca 40 000 years bp was probably wetter than today allowing the southerly expansion of palms beyond their present day distribution grassland compositional changes occurred by ca 33 000 years bp probably resulting from a combination of lowered rainfall decreased temperatures and possibly aboriginal firing activities a reduction in palm at a similar time followed by its complete disappearance in association with the loss of ulmaceae prior to the last glacial maximum lgm indicates a continued trend in decreasing water availability an abundance of cyperaceae sponge spicules and diatoms during the lgm when considered in conjunction with the other evidence possibly represents altered human behaviour in response to increased aridity

study on mode i ii hybrid fracture criteria for the stability analysis of sliding overhanging rock abstract overhanging rock is widely distributed in mountainous regions of the world and therefore poses a potential geohazard to life and property because of fracturing and ultimately failure the maximum circumferential stress criterion is widely used in fracture mechanics however it is inadequate with respect to predicting the failure of sliding overhanging rock that is subject to extension and shear fracturing in this paper the maximum shear stress at a crack tip and a fracture method in combination with the mohr coulomb criterion are used to examine rock with mixed mode i ii fractures the methods are ultimately used to analyze the stability of sliding unstable rocks the two fracture criteria have been compared according to the most unfavorable conditions and the stability of the sliding rock masses are calculated using these new fracture criteria in two case studies the calculations show that the rock stability calculated by the comprehensive fracture criterion is very close to that calculated by the limit equilibrium method but in addition the two methods can also determine the fracture angle overall the maximum shear stress approach and a fracture mechanics criterion based on the mohr coulomb model are more suitable than the limit equilibrium method for evaluating the stability of sliding overhanging rock

preservation of anthropogenic materials under different geochemical processes a mineralogical approach minerals that are preserved or formed inside the sediment or soil can be used to determine whether primary anthropogenic constituents bones phytoliths organic matter charcoal etc would have been affected by diagenesis stability diagrams of the minerals that describe the chemical system under investigation can be constructed and then tested in the field in this approach it is assumed that the stability of the archaeological material of interest is known except for bone there are not many studies on the stability of other archaeological materials this approach does not provide information on the former presence of an archaeological material in the sediment or soil but only whether these materials are stable in such an environment some indirect indication may be provided by unique mineral associations but much more has to be done in this direction

accuracy of topographic maps derived from ers 1 interferometric radar an interferometric radar technique for topographic mapping of surfaces promises a high resolution approach to the generation of digital elevation models the authors present analyses of data collected by the synthetic aperture radar instrument on board the ers 1 satellite on successive orbits use of a single satellite in a nearly repeating orbit is attractive for reducing cost and spaceborne hardware complexity also it permits inference of changes in the surface from the correlation properties of the radar echoes the data have been reduced to correlation maps and digital elevation models the correlation maps show that temporal correlation decreases significantly with time but not necessarily at a constant well defined rate likely depending on environmental factors when correlation among passes remains high however it is possible to form digital elevation models analyses of noise expected in ers 1 interferometric data collected over alaska and the southwestern united states indicate that maps with relative errors less than 5 m rms are possible in some regions however orbit uncertainties imply that tie points are required in order to reduce absolute height errors to a similar magnitude the authors find that about 6 tie points per 40 spl times 40 km scene with 5 m rms or better height accuracy are needed to keep systematic map height errors below 5 m rms the performance of the ers 1 radar system for topographic applications though useful for a variety of regional and local discipline studies may be improved with respect to temporal decorrelation errors and absolute height acuity by modifying the orbit repeat period and incorporating precise orbit determination techniques the resulting implementation will meet many but not all objectives of a global mapping mission

remote surface mapping using orthophotos and geologic maps draped over digital elevation models application to the sheep mountain anticline wyoming remote mapping of surface structures can be conducted by draping digital orthophotos and geologic maps over digital elevation models in geographic information systems formational contacts can be mapped by viewing the intersections of these contacts with the topography on a true to scale three dimensional image bedding orientations can be determined from 1 the trends and slopes of dip slopes or 2 best fit planes to multiple points of intersection of a bedding surface with the topography the methods are tested against mapped formation contacts and bedding attitudes for the sheep mountain anticline in the bighorn basin wyoming detailed mapping of formation contacts is improved by careful observations of the contacts on three dimensional images interpreted bedding attitudes from slope and multiple point solutions show strong positive correlations with field measurements this mapping method provides an efficient and accurate alternative to stereoscopic mapping using aerial photographs and satellite images particularly for remote and inaccessible areas

investigation of the surface roughness of rocks sawn by diamond sawblades surface roughness sr is a measure of the technological quality of a product and a factor that greatly influences manufacturing costs the current study presents an experimental study on the sr of granitic rocks sawn by the diamond sawblades effects of the operating variables on the sr are determined and the sr is correlated with the rock properties morphologies of the wearing surfaces of rocks and the roughness profiles of the measurements are also investigated moreover models are developed depending on both the operating variables and the rock properties for the estimation of the sr results show that the sr increases with the increase of the peripheral speed the traverse speed and the cutting depth while it decreases with the increase of the flow rate of cooling fluid the peripheral speed and the traverse speed are determined as the significant operating variables affecting the sr additionally rather than the mechanical properties of the rock the mineralogical properties are determined as mainly responsible for the sr among the mineralogical properties mean grain size of rock is ranked first in governing the sr the chipping craters scratching grooves and fractures on the rock surface are determined as the characteristics of the diamond sawblade cutting furthermore the modeling results reveal that the developed models have high potential for the estimation of the sr

the lowest place on earth is subsiding an insar interferometric synthetic aperture radar perspective since the early 1990s sinkholes and wide shallow subsidence features wssfs have become major problems along the dead sea shores in israel and jordan sinkholes are readily observed in the field but their locations and timing are unpredictable wssfs are often difficult to observe in the field however once identified they delineate zones of instability and increasing hazard in this study we identify characterize and measure rates of subsidence along the dead sea shores by the interferometric synthetic aperture radar insar technique we analyze 16 sar scenes acquired during the years 1992 to 1999 by the european remote sensing ers 1 and ers 2 satellites the interferograms span periods of between 2 and 71 months wssfs are observed in the lisan peninsula and along the dead sea shores in a variety of appearances including circular and elongate coastal depressions a few hundred meters to a few kilometers in length depressions in ancient alluvial fans and depressions along salt diapir margins phase differences measured in our interferograms correspond to subsidence rates generally in the range of 0 20 mm yr within the studied period with exceptional high rates that exceed 60 mm yr in two specific regions during the study period the level of the dead sea and of the associated ground water has dropped by 6 m this water level drop within an aquifer overlying fine grained marly layers would be expected to have caused aquifer system consolidation resulting in gradual subsidence comparison of our insar observations with calculations of the expected consolidation shows that in areas where marl layers are known to compose part of the upper 30 m of the profile estimated consolidation settlements are of the order of the measured subsidence our observations also show that in certain locations subsidence appears to be structurally controlled by faults seaward landslides and salt domes gradual subsidence is unlikely to be directly related to the sinkholes excluding the use of the wssfs features as predictable precursors to sinkhole formation

taphonomy of phytoliths and macroplants in different soils from olduvai gorge tanzania and the application to plio pleistocene palaeoanthropological samples the abundance and types of phytoliths in the fossil record are taphonomically biased and do not correspond with the macroplant record to better understand the bias and improve the interpretation of samples from olduvai gorge tanzania we analysed the phytoliths from three sample sets modern grasses sedges palm and dicots in the area modern soils in the area and the fossil soils from the eastern palaeolake margin in lowermost bed ii fourier transform infrared spectrometry analyses were performed in parallel to compare the mineral composition of both modern soils and fossil soils we found that the abundance of phytoliths is greatly reduced in soil samples compared with modern plant material but the morphotypes can be reliably interpreted dicotyledonous wood bark phytoliths appear to be over represented in the soil types grass phytoliths and sedges to a lesser degree are preserved in the soils but in lower abundances resulting in these groups being under represented the macroplant fossils are fragments of grass and sedge aerial culms and dicotyledonous stems that are preserved in fluvial and lacustrine deposits it is suggested that phytoliths represent the continuous flora whereas macroplant fossils represent the more robust tissues of selected plants preserved under more catastrophic conditions a post depositional model is proposed and the palaeovegetation is reinterpreted as being richer and more complex than indicated by other fossil data

behavior of microcontacts in rock joints under direct shear creep loading abstract two types of fractures were induced in sandstone by means of modified shear and indirect tension the fractured rock samples were assembled following their initial formation and direct shear tests were performed under a constant normal force and stepwise increased shear creep loadings using computerized tomography ct and laser scanning the micro contact mechanism of the fractured rock surfaces were observed and measured before during and after the shear tests under a moderate normal force dilation tends to occur in the shear fractured rocks with the increase of normal force the peak shear strength of tensile fractured rocks grows faster than that of shear fractured rocks and eventually gives rise to a higher value a few micro contact modes and fracture phenomena of the rough surfaces in contact are recognized through ct and laser scanning images such as shear off of micro asperities friction between macrowaved rough surfaces migration of worn debris propagation and healing up of hybrid cracks in subsurface the long term shear strength of fractured rocks is mainly composed of two mechanisms one is the shear resistance raised from interlocked microasperities in the scale of roughness in tensile fractured rocks the other is the frictional resistance produced between macroasperities in the scale of waviness on the shear fractured rocks the microcontact configuration and contact area are observed and measured by slice cutting of the mated rough surfaces in contact two distinct patterns of contacts in rock joints are recognized term as coastline pattern and islands pattern the shear strength of fractured rocks is closely related to the maximum contact area and the surface roughness

geodetic airborne laser altimetry of breidamerkurjokull and skeidararjokull iceland and jakobshavns isbrae west greenland

non stationary and nonlinear visco elastic shear creep model for shale abstract based on visco elastic shear creep experimental results of shale with four various shear stress levels a new non stationary and nonlinear visco elastic shear creep model is put forward first stationary linear visco elastic shear creep model is used to identify the creep parameters by the discrimination criterion of the square of correlation coefficient r 2 and sum of least error square q in stationary linear visco elastic shear creep model the visco elastic shear modulus g 2 of shale decreases but the visco coefficient 1 increases with increasing time which has distinct time scale effect then by constructing the relation between stationary creep parameters g 2 1 and time a non stationary visco elastic shear creep model is put forward to describe visco elastic shear creep deformation behavior of shale the non stationary shear creep model has a better agreement with the experimental data than does the stationary shear creep model but fails in predicting long term deformation characteristics therefore by introducing a time index a nonlinear visco elastic shear creep model is constructed which can predict better for long term deformation behavior of shale in the end based on the relation between nonlinear creep parameters and shear stress the shear creep deformation with all kinds of shear stress levels is predicted approximately in the range of 0 45 mpa 1 45 mpa

phytolith evidence for hearths and beds in the late mousterian occupations of esquilleu cave cantabria spain esquilleu cave site has provided a moderately well preserved archaeological cave deposit from the late pleistocene in the cantabrian area phytolith quantification identification and determination of the refractive index have been carried out together with ftir analyses from sediment samples collected in the profile the comparison of the data obtained with the previous micromorphological results allows us to make inferences about the site formation processes and the neanderthals use of the cave phytolith results show the presence of grass leaves nearby the hearth suggesting the repetitive existence of a bedding zone on the same area neanderthal behavioral patterns should be revised on the light of high resolution analyses since diagenetic processes can obscure the existence of differentiated activity areas in the site

plio pleistocene macroplant fossil remains and phytoliths from lowermost bed ii in the eastern palaeolake margin of olduvai gorge tanzania abstract fossil macroplants and phytoliths occur in the sediments of the palaeoanthropological site of olduvai gorge northern tanzania current research on hominin land use in the basin during the plio pleistocene has a strong palaeoenvironmental emphasis on the palaeovegetation in particular the occurrence of macroplants and phytoliths at olduvai and their usefulness and reliability for palaeovegetation interpretation are assessed here for the first time modern reference collections from analogous environments have been established and used to identify the fossil taxa from the eastern palaeolake margin of lowermost bed ii as the test case for very detailed spatially and temporally constrained vegetation reconstruction fourier transform infrared spectrometry ftir analysis was used to identify the minerals of the fossil sediments modern plants produce more phytoliths than are preserved in the fossil soils but there were sufficient numbers to show diverse and changing vegetation over short time periods silicified macroplant fragments of sedge culms and dicot stems occur with phytoliths but do not always represent the same plant taxa a more complex flora was shown when using both forms of fossil plants during lowermost bed ii times at the locality of flkn monocots and dicots occurred indicating the presence of marshland and grassland after the deposition of tuff if at vek the phytoliths indicate a shift in dominance from dicots to monocots to a mixture of the two and including palms at hwkee initially palms dominated then there was a mixture of palms grasses and dicots the vegetation at mck comprised dicots monocots sedges and grasses this detailed vegetation data complements the more broad scale vegetation interpretations that have been deduced from the pollen isotopes and faunal data sets

creep properties of intact and fractured muddy siltstone the experiments were conducted in the rock mechanics laboratory of nottingham centre for geomechanics ncg as part of a research project funded through the research programme of the research fund for coal and steel grant numbers rfcr ct 2003 00011

evolution of lakes created by landslide dams and the role of dam erosion a case study of the jiajun landslide on the dadu river china abstract during the late pleistocene strong erosional riverine environments led to the widespread occurrence of landslides along the river valleys in southwestern china such landslides along the middle reaches of the dadu river often caused large scale dammed lakes in this study the typical large scale jiajun landslide and its associated dammed lake were investigated the relatively complete sedimentary sequence of the lake was examined and multi depositional characteristics were found analysis of the history of the dammed lake revealed the relationship between its formation and the river valley erosion the evolution of the dammed lake was reconstructed based on changes of the sedimentary environments we concluded that the lake experienced two stages of high lake level stable lacustrine sedimentation during this period a two stage large scale dam breach and retention periods lasting more than 100 years the relationship between the formation of the ancient barrier lake and the river valley erosion in the middle reaches of the dadu river is indicative of the erosive and depositional environments the evolution of the ancient dammed river landslide valley had considerable effect on valley erosion and the sedimentary environment of the dadu river

formation processes through archaeobotanical remains the case of the bronze age levels in el mirador cave sierra de atapuerca spain el mirador site has a sequence formed by burnt dung resulting from pastoral activities during the bronze age and the neolithic period because there is a high sediment variation in the profile facies descriptions were used to guide the archaeologists in their work paleobotanical and mineralogical analyses were used to describe and understand the formation of the facies from the mir 4 level furthermore the paleobotanical results serve to reconstruct the landscape in atapuerca during the bronze age most seeds recovered are from triticum aestivum durum but other cereals and also leguminoseae and fruits have been identified charcoal analysis has yielded mainly deciduous and evergreen quercus pollen analysis has revealed a low arboreal cover with pinus quercus and riverside trees most of the pollen record corresponds to herbs such as poaceae and asteraceae all these results indicate a mosaic of different biota with forest pastureland and cultivated fields near the site most of the phytoliths come from the leaves and stems of festucoid grasses however there are some differences in the phytolith type and number the amount of faecal spherulites the mineralogical composition and the percentage of multicellular structures that indicate that not all the facies in the site have been formed in the same way thus the work carried out has demonstrated that some facies are related more to agricultural activities than to pastoralism activities and that other facies have been affected by incipient diagenetic processes

bat guano and preservation of archaeological remains in cave sites the formation of authigenic minerals in cave sediments can be used to reconstruct the paleochemical conditions that prevailed in the past and in this way to assess the completeness of the archaeological record previous studies indicated that the major driving mechanisms for chemical diagenesis in prehistoric caves that result in the formation of authigenic minerals are the degradation of bat guano and the local hydrology we therefore investigated contemporary bat guano deposits in caves and the sediments directly below such deposits the emerging patterns show that the formation of authigenic minerals occurs under acidic conditions within tens of years the availability of phosphate al k and fe increases with increasing organic matter degradation while the availability of nitrogen and sulfur decreases insectivorous bat guano contains larger amounts of phosphate and is more acidic than fruit bat guano in the first stages of diagenesis micro chemical environments form within the degrading bat guano that result in the formation of a wide variety of authigenic minerals during advanced stages of diagenesis steady state conditions are achieved resulting in authigenic mineral assemblages being dominated by one mineral type at the same locale this is reminiscent of known distributions of authigenic minerals in prehistoric cave sediments under the acidic conditions produced by degrading bat guano deposits calcareous artifacts and bones are not expected to persist for long periods of time unless there is a lot of calcite in the sediments that could buffer the sediment water ph guano itself is not likely to be preserved periods of cave abandonment can be inferred from the presence of authigenic minerals in the sediments as it is during these times that bats mainly occupy the cave the occurrence of certain authigenic minerals in open air sites may serve as evidence for areas rich in organic matter containing phosphate i e animal enclosures latrines sewers trash pits and or bones as the degradation process is rapid the use of authigenic minerals to identify these loci is relevant to almost all archaeological as well as historical sites

empirical ratio of dynamic to static stiffness for propped artificial fractures under variable normal stress abstract the stiffness coefficient is a key parameter of rock fractures that controls the properties and behavior of a rock mass according to the displacement discontinuity theory the dynamic stiffness of rock fractures can be back analyzed using stress wave propagation this study aims to measure the dynamic stiffness of rock fractures then develop an empirical ratio to describe the relationship between dynamic and static stiffness propped artificially fractured shale and granitic rock samples are employed mechanical and ultrasonic tests are conducted on two artificial rock fractures during uniaxial loading and unloading as normal stress changes from 1 mpa to 50 mpa the average dynamic normal stiffness of shale and granitic rock fractures changes from 330 gpa m to 1960 gpa m and from 90 gpa m to 2320 gpa m respectively for both artificial fractures the dynamic stiffness is higher than the static stiffness but approaches the static stiffness with increasing normal stress the ratio of dynamic to static normal stiffness is approximately 2 0 at a normal stress of 15 mpa this ratio approaches 1 0 with increasing normal stress and varies widely under low normal stress this study provides a method for evaluating the static or dynamic stiffness of rock fractures which has important applications for seismic surveys or acoustic logs in the field of geological engineering

shear creep tests on fissured mudstone and an improved time dependent model all rocks undergo creep when under a long term load and shear sliding is a major failure mode of natural slopes however the mechanical properties of fractured mudstone differ from those of intact rock to investigate these properties and the influence of normal stress and pre cut crack length on mudstone shear creep characteristics we performed shear creep tests on fractured mudstone the experimental results show that axial load magnitude and crack length have a marked influence on the rock s shear creep behavior the larger the axial compressive stress the smaller the shear creep deformation the longer the crack the more significant the shear creep deformation when stress is low existing creep models can reflect the creep properties of mudstone well however most published creep models cannot accurately portray the nonlinear creep behavior of mudstone in a tertiary creep stage we propose an improved time dependent creep model that overcomes the shortcomings of the traditional models in describing nonlinear creep the new model has fewer parameters and can be applied to practical engineering problems involving soft rock during the shear creep tests on soft argillaceous samples under different loads shear failure zones in fractured mudstone exhibited both gradual and sudden failure the shear time dependent model for mudstone developed in this study can effectively explain mudstone instability

atmospheric effect correction for insar with wavelet decomposition based correlation analysis between multipolarization interferograms this paper presents a wavelet decomposition based correlation analysis wdca method to correct atmospheric effects for interferometric synthetic aperture radar interferometry the main idea is based on the a priori knowledge that the atmospheric effects are independent of the polarizations this provides the possibility to find the identical atmospheric phases atps from the two different polarimetric interferograms to achieve this goal differential interferometry is performed with different topographic data so that the obtained differential interferograms d infs have different topographic errors a polynomial incorporating topographic information is then used to remove the orbit error phase thus the atps are the only identical components in the obtained d infs a forward wavelet transform is then utilized to perform multiresolution analysis for the two obtained d infs after this we apply correlation analysis to identify the wavelet coefficients attributed to the atmospheric effects the corrected d infs are then obtained by down weighting the wavelet coefficients during inverse wavelet transform the performance of the wdca method was tested with l band alos 1 palsar dual polarization sar images acquired over southern california and qilian mountain test sites characterized by different topographic conditions for the southern california test site two interferometric pairs with long and short baselines 750 and 50 m were formulated the results show that the wdca method can work well for both of the interferometric pairs and the root mean square errors rmses of the obtained dems with respect to the shuttle radar topography mission digital elevation model dem are 7 86 and 13 78 m and show a decrease of 34 7 and 80 4 for the long and short baseline cases respectively for the qilian mountain test site the corrected interferogram can provide a dem with an rmse of 19 73 m which is an improvement of 22 3 with respect to the dem containing the atmospheric signals in addition the above two experiments show that compared with the existing topographic information based wavelet method this approach can remove not only the topography dependent atp but also the turbulent atp

studies of multibaseline spaceborne interferometric synthetic aperture radars the authors have utilized a set of seasat synthetic aperture radar sar data that were obtained in nearly repeat ground track orbits to demonstrate the performance of spaceborne interferometric sar insar systems an assessment of the topography measurement capability is presented a phase measurement error model is described and compared with the data obtained at various baseline separations and signal to noise ratios finally the implications of these results on future spaceborne insar design are discussed

mapping of glacial motion and surface topography of hielo patagonico norte chile using satellite sar l band interferometry data the first topographic and ice motion maps of the northwestern flank of hielo patagonico norte hpn northern patagonia icefield in chile were produced using satellite synthetic aperture interferometric radar data acquired by nasa s spaceborne imaging radar c instrument in october 1994 the topographic map has a io m vertical precision with a 30 m horizontal spacing which should be sufficient to serve as a reference for monitoring future mass changes of the icefield the ice motion map is accurate to within 4 mm d or 1 ma the radar derived surface topography and ice velocity are used to estimate the ice discharge from the accumulation area of four outlet glaciers and the calving flux and mass balance of glaciar san rafael the results demonstrate the use of sar interferometry for monitoring glaciological parameters on a spatial and temporal scale unattainable by any other means

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

sir c x sar multifrequency multipass interferometry a new tool for geological interpretation radar remote sensing is a tool of increasing importance in the study of volcanic sites synthetic aperture radar sar is a high resolution imaging tool used to survey areas which are not practical or safe to be directly inspected with the introduction of the across track sar interferometry ifsar technique digital elevation models dem can be produced the usefulness of such interferometric products depends on the ability to extract information that can be used for geological interpretation we analyzed the shuttle imaging radar c sir c x sar multifrequency multipass interferometry mission over mount etna sicily and we performed a supervised geological interpretation of the coherence maps and a fractal based analysis of the ifsar dems the first permits us to recognize different volcanic terrain and to distinguish between vegetated and unvegetated areas while the second allows us to validate the ifsar dems and to detect large scale geological features this latter analysis performed over the photogrammetric dem enabled us to recognize artifacts caused by digitizing and resampling obviously ifsar dems are not affected by these problems as a consequence ifsar products are a valuable aid in geological interpretation

experimental study and modeling of shear rheology in sandstone with non persistent joints abstract understanding the long term mechanical behavior of cracks in rock masses is important for engineering projects and for controlling rock mass stability particularly on rock slopes in this study laboratory prepared cubic sandstone samples with non persistent joints were subjected to shear creep testing using a rock shear rheometer the results indicate that long term shear strength is influenced by the long term internal friction angle and cohesion and decreasing cohesion is a key factor for changes in long term shear strength under constant load additionally damage to the shear modulus is related to the initial damage conditions and joint persistence of the samples a new creep model is developed that considers the effect of crack or joint length on time dependent rock behavior the elasto viscoplastic behavior of non linear creep is also described the modified shear creep model shows promising results for estimation of failure time shear creep deformation and long term stability of a rock slope for cases where planar type failure occurs along a crack or joint surfaces in which no cohesion exists in the crack or joint surface contacts

phytoliths in the middle palaeolithic deposits of kebara cave mt carmel israel study of the plant materials used for fuel and other purposes abstract kebara cave israel is a well studied archaeological site it contains abundant visible hearths ash derived minerals are a major component of the mousterian sediments and are present in varying states of preservation furthermore archaeobotanic information is available from charred remains kebara cave is thus an ideal location to study the potential of phytoliths to provide information on the mode of fire use in the cave to assess the input of other plant materials as well as to determine the effects of diagenesis on phytolith preservation twenty samples were analysed in terms of their mineralogy phytolith contents per unit weight of acid insoluble fraction and phytolith morphologies in general the preservation of the phytoliths is good except for the two samples in which the mineral component associated at present with the phytoliths is mainly ash derived calcite the cave sediments contain about ten times more phytoliths than those present in the four samples analysed from outside the cave the major source of plant material input into the cave is clearly from the wood and bark used for the fuel for fires the grass phytoliths present in the samples are also thought in part to have been brought into the cave associated with the wood bark fuel sediments from the hearths as well as those between the hearths contain abundant wood bark phytoliths the two samples of the latter contain appreciable amounts of phytoliths not known to be present in wood and bark as do other hearth derived samples plant materials other than those used as fuel were thus also brought into the cave this study shows that phytolith analyses in conjunction with detailed mineralogical stratigraphic archaeobotanic and field information can provide a more complete understanding of the use of plant materials in prehistoric caves for fuel

the topsar interferometric radar topographic mapping instrument the authors have augmented the nasa dc 8 airsar instrument with a pair of c band antennas displaced across track to form an interferometer sensitive to topographic variations of the earth s surface during the 1991 dc 8 flight campaign data were acquired over several sites in the us and europe and topographic maps were produced from several of these flight lines analysis of the results indicate that statistical errors are in the 2 4 m range while systematic effects due to aircraft motion are in the 10 20 m range the initial results from development of a second generation processor show that aircraft motion compensation algorithms reduce the systematic variations to 2 m while the statistical errors are reduced to 2 3 m

topographic mapping using radar interferometry processing techniques a new processing algorithm for the nasa jpl topsar topographic radar mapper is described it incorporates extensive motion compensation features as well as accurate three dimensional target location algorithm the processor applies an algorithm to resolving the absolute phase ambiguity this allows rectified height maps to be generated without any use of ground reference points the processor was tested using data acquired with extreme aircraft motion so that performance could be evaluated under adverse conditions the topographic maps generated by the radar were compared to digital elevation models dems derived using conventional optical stereo techniques in one region the rms elevation deviations measured were less than the specified dem accuracy and in the region covered by the more accurate dem errors varied from 2 2 m rms in relatively flat terrain up to 5 0 m in mountainous area the rms difference between radar and dem elevation over the 6 5 km by 22 km area covered by the more accurate dem was 3 6 m

ground based radar interferometry for landslides monitoring atmospheric and instrumental decorrelation sources on experimental data the application of ground based radar interferometry for landslide monitoring is analyzed a case study based on an experimental campaign carried out in italy during 2002 is discussed interferometric data obtained from coherent synthetic aperture radar sar images acquired by means of c band ground based equipment are analyzed the campaign was aimed at retrieving potential terrain movements of a small landslide observed hundreds of meters away critical aspects related to spatial and temporal decorrelation are discussed the use of optical photogrammetry as a technique for evaluating mechanical stability and correcting geometric distortion is presented results also confirmed that the application of ground based radar interferometry can be attractive and effective if the acquired sar images maintain an adequate coherence on different dates

deformation and seismicity in the coso geothermal area inyo county california observations and modeling using satellite radar interferometry interferometric synthetic aperture radar insar data collected in the coso geothermal area eastern california during 1993 1999 indicate ground subsidence over a 50 km 2 region that approximately coincides with the production area of the coso geothermal plant the maximum subsidence rate in the peak of the anomaly is 3 5 cm yr 1 and the average volumetric rate of subsidence is of the order of 10 6 m 3 yr 1 the radar interferograms reveal a complex deformation pattern with at least two irregular subsidence peaks in the northern part of the anomaly and a region of relative uplift on the south we invert the insar displacement data for the positions geometry and relative strengths of the deformation sources at depth using a nonlinear least squares minimization algorithm we use elastic solutions for a prolate uniformly pressurized spheroidal cavity in a semi infinite body as basis functions for our inversions source depths inferred from our simulations range from 1 to 3 km which corresponds to the production depths of the coso geothermal plant underpressures in the geothermal reservoir inferred from the inversion are of the order of 0 1 1 mpa except a few abnormally high underpressures that are apparently biased toward the small source dimensions analysis of the insar data covering consecutive time intervals indicates that the depths and or horizontal extent of the deformation sources may increase with time this increase presumably reflects increasing volumes of the subsurface reservoir affected by the geothermal exploitation we show that clusters of microearthquakes associated with the geothermal power operation may result from perturbations in the pore fluid pressure as well as normal and shear stresses caused by the deflation of the geothermal reservoir

time dependent drift degradation due to the progressive failure of rock bridges along discontinuities an important element of time dependent drift degradation is the progressive failure of intact segments along discontinuities referred to as rock bridges a fracture mechanics model is developed to simulate the time dependent failure of rock bridges along discontinuities the time dependence of the rock bridge failure process is modeled utilizing subcritical crack growth the rock bridges give an effective cohesion to the discontinuities and this cohesion is time dependent due to the time dependent failure of the rock bridges the resulting first order differential equation for joint cohesion is implemented into the udec distinct element numerical code to model time dependent drift degradation the model and its implementation into udec are validated using several simple examples including a direct shear test and a rigid block on a slope two time dependent drift degradation examples are then shown one with and one without thermal loading these examples used similar geometry material parameters and in situ stresses as for the proposed underground drifts for the storage of nuclear waste at yucca mountain both with and without thermal loading a large zone develops around the excavation where the joint cohesion and tensile strength drop to zero due to the failure of rock bridges this in turn results in an excavation that is significantly less stable than if time dependence was not included the results demonstrate the importance of time dependence on the stability of underground excavations in hard rock

on the presence of gypsum in the archaeological burial site of cova des pas menorca western mediterranean abstract the cova des pas ferreries menorca is a cave that was used as a collective sepulcher during the late bronze age 1100 800 b c apart from the archaeological and paleoanthropological attractiveness of the site it stands out for its excellent preservation of organic remains in this paper we study the micromorphology of the human and organic remains in order to assess the preservation conditions and in particular to elucidate the presence of gypsum found mainly on human remains plant fibers and shrouds in order to do this a detailed description of the geological and geomorphological environment of the cave is provided gypsum is present as microcrystalline gypsum resulting from diagenetic process in this cave due to the lack of any other gypsum source and based on its location and morphology the gypsum is interpreted to be a consequence of the oxidation of organic sulphur from the buried bodies which later precipitated with the calcium present in the substrate the location morphology and lithology of the deposit have contributed to the arid environmental conditions thus avoiding the leaching of gypsum and favouring the preservation of the remains and materials of organic origin which is rare in archaeological contexts

slip distribution of the 1997 umbria marche earthquake sequence joint inversion of gps and synthetic aperture radar interferometry data 1 in september october 1997 a seismic sequence struck the southern part of the umbria marche region in central italy the three largest earthquakes took place on 26 september 0033 ut mw 5 7 09 40 gu mw 6 0 near colfiorito and on 14 october mw 5 6 near sellano we present a slip model for the main sequence over two separate fault planes we use previously published global positioning system gps and differential interferometric synthetic aperture radar dinsar data as well as new dinsar data covering the sellano event as input to a simulated annealing solution for the distribution of fault slip the combination of both types of geodetic data as well as the combination of sar interferograms from both ascending and descending satellite tracks allows us to make a more complete geodetically based assessment of the fault slip for these earthquakes for the solutions presented here we required the slip distribution to match the observed surface displacements while maintaining a total scalar seismic moment approximately equal to the seismologically inferred moments for this sequence we find the slip was concentrated in a zone at 4 5 5 km depth with a shallower tail extending to near the surface at the northern end of the colfiorito sequence for both the second colfiorito event and the sellano event individual patches were calculated with maximum slip of 2 m implying stress drops as high as 20 mpa coulomb stress calculations show that the coseismic slip distribution for the colfiorito events facilitated slip of the adjacent sellano earthquake

microarchaeology of a collective burial cova des pas minorca ftir and phytolith analyses have been used to understand the exceptional preservation of the organic remains at the burial cave of cova des pas minorca and to obtain high resolution data of the plant remains present in the sediments the presence of sodium nitrate and gypsum suggests a relatively dry environment that has enabled the preservation of the organic material and contributed to the natural mummification the dry conditions also favored phytolith preservation grass inflorescence phytoliths are abundant all over the site suggesting that phytolith accumulations might have an anthropogenic origin and are related to the burial ritual

generation of highly accurate dems over flat areas by means of dual frequency and dual baseline airborne sar interferometry in this paper a dual frequency and dual baseline dfdb processing framework for the extraction of high precision terrain information from airborne interferometric synthetic aperture radar sar data is presented specifically we propose the use of two single pass data sets acquired simultaneously in two different frequency bands and two large baseline repeat pass data sets also acquired simultaneously in two frequency bands the configuration profits from the stability of the single pass derived elevation maps in relation to spatially correlated artifacts as well as from the increased sensitivity associated with large baseline acquisitions moreover the dual frequency nature of the data set enables the tackling of the phase unwrapping issue promoting the retrieval of unambiguous measurements several algorithms for the interferometric processing of the dfdb airborne data set are proposed including the outline of multichannel phase calibration and unwrapping error correction strategies and approaches to remove spatially correlated artifacts and extract the common underlying topography elevation models generated from a dfdb data set acquired with the airborne f sar sensor over tidal flats in northern germany are presented and comparisons with an airborne laser scanner reference show errors with a standard deviation of around 14 cm and a mean absolute deviation of less than 10 cm