deep seated gravitational slope deformations related landslides and tectonics abstract deep seated gravitational slope deformations and their relationships with tectonic deformation of rocks is considered to examine the viewpoint of tectonics as a causative factor in slope deformation first a distinction is made between the different types of deep seated gravitational slope deformation then the geomorphological and structural effects of the different macrostructural deformations induced by tectonics on the scale of the whole deforming ridge is briefly discussed finally some case studies that represent either verified or possible cases of gravity deformation in response to tectonic activity are used as illustration

paraglacial rock slope stability glaciation and deglaciation along with their associated climatic and non climatic processes modify slope stresses and influence slope stability paraglacial slope failures are those that are a part of or influenced by the transition from glacial conditions to non glacial conditions gravitational failure of rock slopes is a primary and dominant process of slope evolution in mountainous terrain and is the subject of this paper which 1 reviews the approaches taken for researching paraglacial rock slope failure patterns and processes 2 summarises the spatial and temporal patterns of post glacial failures 3 assesses the factors influencing slope stability during glaciation and deglaciation 4 explores some of the applications of paraglacial research and 5 highlights some of the outstanding issues to be resolved and provides recommendations for terminology relating to paraglacial slope processes

extensive deformations of rock slopes in southern coast mountains southwest british columbia canada extensive deformations of mountain slopes occur in crystalline intrusive rocks in the southern coast mountains of british columbia typical morphological evidence of slope movement includes extensive systems of tension cracks grabens and antislope scarps collectively referred to here as linears these landforms involve displacements along penetrative joints observed in surface exposures kinematic tests on rock structural data indicate that the observed patterns of linears are generally consistent with the feasible gravitational movements along the dominant discontinuities most sites indicate sliding as the most likely initial mode of movement followed by or accompanied by toppling and toppling induced sliding movements and do not support the view that linears are the traces of active faults

quantification of sediment transport by rockfall and rockslide processes on a proglacial rock slope kaunertal austria abstract rockfalls and rockslides are significant geomorphic processes on high alpine proglacial rock slopes in this study we quantitatively evaluate sediment transport on a recently deglaciated rock slope that is directly connected to the shrinking gepatschferner glacier by multi temporal terrestrial and airborne lidar observations according to the lidar measurements sediment transport by gravitational mass movements on this single proglacial rock slope 0 2 km 2 yielded 159 gj a geomorphic work the most significant part 141 gj a was released by rockfall while 18 gj a were performed by the sliding activity of a 1 250 000 m 3 large unstable rock mass the results indicate that slope development and talus formation in proglacial environments may be a rapid process despite of being caused by continuous rockfall activity over several millennia

onset and timing of deep seated gravitational slope deformations in the eastern alps italy abstract a previously unrecognised complex of deep seated gravitational slope deformations dsgsd extends 20 km along upper venosta valley in the eastern alps italy mt watles exhibits spectacular features indicative of dsgsds including double ridges trenches and counterscarps the slope deformation occurs along a nappe boundary now corresponding to the schlinig normal fault is also conditioned by recent faults marked by shallow earthquakes and shows glacial paraglacial controls on slope evolution the mt watles dsgsd is a complex deep seated compound slide along a basal shear zone involving the schlinig fault gravitational reactivation of ne trending fractures formed gravitational scarps counterscarps and half grabens in the upper slope whereas the lower part of the slope partially collapsed although our work indicates the importance of the schlinig fault and recent fracturing on slope failure the trigger seems to be postglacial debuttressing of the valley walls radiocarbon dating of peat deposits within one of the major counterscarps indicates that slope deformation started during the lateglacial period and continued during the holocene in several slope sectors

modeling offset dependent reflectivity for time lapse monitoring of water flood production in thin layered reservoirs the objective of this case study is to predict whether 5 years of water flood production from a thinly layered gulf of mexico reservoir will change its seismic amplitude variation with offset avo response in a detectable manner density and velocity profiles were computed from in situ wireline logs for 100 oil gas and brine saturations and for a 5 year prediction that was based on a fluid flow and production simulation analytical avo curves for simple half space models did not match avo curves extracted from synthetic seismograms computed with a full waveform layer stack algorithm several different amplitude corrections were tried to reduce the avo curves from the synthetic data to the analytical ones but ultimately none was deemed satisfactory instead avo change attributes based on relative changes polarity changes or ratios were used attributes based on the change of avo gradient were perceived to be most diagnostic of the water flood but they were also overly sensitive to interference noise and amplitude correction errors for field data from the study area a large decrease in intercept magnitude may be the best indicator of the waterfront

integration of seismic methods with reservoir simulation pikes peak heavy oil field saskatchewan reservoir characterization is essential for providing optimal recovery from heavy oil fields the process of reservoir characterization is demonstrated for a steam injection project at pikes peak heavy oil field near lloydminster saskatchewan canada geologic geophysical and reservoir engineering data are used to improve the interpretation of reservoir conditions there is ambiguity in modeling any of these data however in modeling all data sets in cooperative inversion ambiguity is decreased thereby enhancing our knowledge of the reservoir one of the main benefits of this oil field modeling is that bypassed oil and steam fronts are effectively mapped

valley formation by fluvial and glacial erosion cross valley profiles from the west slope of the olympic peninsula washington are used to investigate the relative effects of fluvial and glacial erosion on valley formation unlike most ranges where glaciers and rivers sequentially occupied the same valleys neighboring valleys in the olympic mountains developed in similar lithologies but were subject to different degrees of glaciation allowing comparison of the net effect of glacial and fluvial processes integrated over many glacial cycles upslope drainage area was used to normalize comparisons of valley width ridge crest to valley bottom relief and valley cross sectional area as measures of net differences in the mass of rock excavated from below ridgelines for 131 valley spanning transects valley width relief and cross sectional areas are similar for glaciated partly glaciated and unglaciated fluvial valleys with drainage areas of 10 km 2 but diverge downslope glaciated valleys draining 50 km 2 reach two to four times the cross sectional area and have to 500 m greater relief than comparable fluvial valleys partly glaciated valleys have intermediate dimensions at distances of 5 km from valley heads the cumulative upstream volume of rock removed to form valleys is two to four times greater in glacially incised valleys than in fluvial valleys the finding of strong differences in the net result of valley excavation by fluvial and glacial erosion supports the interpretation that alpine glaciers are more effective erosional agents than are rivers and implies that large alpine valleys deepened and enlarged in response to pleistocene glaciation

numerical simulations of glacial valley longitudinal profile evolution glaciers shape alpine landscapes they broaden valley bottoms enhance local valley relief generate multiple steps overdeepen valley floors and cause tributary valleys to hang these distinctive glacial signatures result from 10 4 10 5 yr of erosion during which swings in climate drive advances and retreats of alpine glaciers we use a numerical model of glacial erosion to explore the development of the longitudinal profiles of glaciated valleys the model is driven by the past 400 k y of variable climate because both sliding speed which dictates abrasion rate and water pressure fluctuations which strongly modulate quarrying rate should peak at the equilibrium line altitude ela we expect the locus of most rapid erosion to follow the transient ela simulations of a single glacial valley show rapid flattening of the longitudinal profile inclusion of a tributary glacier creates a step immediately downvalley of the tributary junction that persists over multiple glaciations and commonly leaves the tributary valley hanging steps and overdeepenings result from an increase in ice discharge immediately below the tributary junction which is accommodated primarily by increased ice thickness and hence sliding rate the size of the step increases with the ratio of tributary to trunk ice discharge while the height of a hanging valley reflects the difference in the time integrated ice discharge in tributary and trunk valleys and therefore increases as the discharge ratio decreases

sediment generation and delivery from large historic landslides in the southern alps new zealand abstract there is much variability of sediment yield in mountain river systems because it is influenced by both periodic e g snowmelt monsoonal circulation and episodic high intensity rainstorms earthquakes controls in the southern alps of new zealand landslides are dominant mechanisms of conveying large amounts of debris to river channels this paper attempts to quantify catastrophic modes of sediment delivery by presenting three recent examples of large landslides on the western slopes of the southern alps a combination of ground surveys dem based volume calculations and air photo interpretation attributes immediate postfailure sediment yields in excess of 70 000 t km 2 a 1 in the short term such landslide derived sediment pulses pose significant hazards to downstream settlements and infrastructure on alluvial fans where they cause massive aggradation increased flooding frequency and large scale channel avulsion in addition to intramontane valley floor obliteration or channel metamorphosis these geomorphic impacts may thus occur far beyond the initial locations of slope failure these catastrophic off site effects involve apparent net sediment delivery rates in the order of 10 5 10 6 m 3 a 1 the accurate quantification of the relative contribution of debris from the disturbing landslide to overall sediment flux is extremely difficult nonetheless are quantitative estimates of landslide derived sediment production and delivery important data to develop a more comprehensive understanding of the variability in alpine sediment flux such data are essential not only for use in hydraulic engineering or catchment management but also in gauging potential future impacts from rainstorm and earthquake induced landsliding in the southern alps

rock slope instability and erosion toward improved process understanding rock slopes in a range of environments are among the landscape elements most sensitive to climate change the latter affecting rock mass properties altering slope boundary conditions and changing geosystem configurations major climate dependent influences promoting destabilization include stress redistribution with changing glacial ice extents degradation of mountain permafrost altered slope hydrology and weathering environments loading and unloading due to deposition and erosion and changes in the spectrum of magnitude and frequency of driving forces in steep bedrock terrain erosional processes control slope morphology by modulating rates of i weathering in response to climate and pre disposition ii rock slope retreat in response to magnitude and frequency of detachment and iii channel incision or valley infilling in response to variable sediment supply modelling landscape evolution and anticipating natural hazards in these environments thus requires deeper insights into the processes driving rock slope instability and erosion this special issue emphasizes new understanding of rock slope processes through a collection of manuscripts at the forefront of research in the field copyright 2014 john wiley sons ltd

streamline based integration of time lapse seismic and production data into petroleum reservoir models abstractwe have developed an efficient approach of petroleum reservoir model calibration that integrates 4d seismic surveys together with well production data the approach is particularly well suited for the calibration of high resolution reservoir properties permeability because the field scale seismic data are areally dense whereas the production data are effectively averaged over interwell spacing the joint calibration procedure is performed using streamline based sensitivities derived from finite difference flow simulation the inverted seismic data i e changes in elastic impedance or fluid saturations are distributed as a 3d high resolution grid cell property the sensitivities of the seismic and production surveillance data to perturbations in absolute permeability at individual grid cells are efficiently computed via semianalytical streamline techniques we generalize previous formulations of streamline based seismic inversion to incorporate realistic field situations such as changing boun

repeatability issues of 3 d vsp data increased repeatability is recognized as one major issue for improving the time lapse seismic technology as a reservoir management tool a 3 d vertical seismic profiling vsp data set acquired over a period of two days is used to analyze how repeatable a permanent installed geophone array can be and how repeatability changes with inaccuracies in source positioning it is found that for a frequency range between 3 5 and 50 hz the difference root mean square rms level between two recorded traces belonging to two different shots is about 8 this fact shows that there is a potential for acquiring very accurate time lapse seismic data by using a permanently installed downhole geophone array repeatability variation with increasing shot separation distances is analyzed showing a rapid decrease in repeatability as the accuracy of the positioning of the repeat survey decreases horizontal geophone components show approximately the same degree of repeatability compared to the vertical component but horizontal geophone data is slightly more sensitive to positioning errors the results show that repeated 3 d vsp surveys preferably using permanently installed geophone arrays might be an efficient tool for detailed and precise monitoring of fluid and pressure changes within a hydrocarbon reservoir

combined observations of rock mass movements using satellite sar interferometry differential gps airborne digital photogrammetry and airborne photography interpretation 1 recent global warming through the related retreat of mountain glaciers causes a growing number of different slope instabilities requiring accurate and cost effective monitoring we investigate the potential of combined remote sensing observations from satellite and airborne microwave and optical sensors for an efficient survey of mountainous ground displacements the evolution of a paraglacial deep seated rock mass movement due to glacier retreat in the swiss alps has been observed between 1976 and 2008 with satellite synthetic aperture radar sar interferometry differential gps and airborne digital photogrammetry analysis of differential sar interferograms revealed an acceleration of the landslide from 4 cm yr in the slope parallel direction during the mid 1990s to more than 30 cm yr in the summer of 2008 differential gps surveys performed between the summers of 2007 and 2008 indicate seasonal variations of the landslide activity the photogrammetric analysis revealed no significant movement i e 1 cm yr between 1976 and 1995 and provides an overview of the total displacement between 1995 and 2006 with high spatial resolution in situ and airborne photography interpretation suggests that the landslide was activated at earliest by the end of the last glaciation but without any significant long lasting activity during the holocene and that the exponentially increasing reactivation since the 1990s is the result of ongoing debutressing of the valley flank due to the glacier retreat in combination with strong precipitation and snowmelt events we conclude that the employed remote sensing techniques complement each other well within a landslide hazard assessment procedure

uphill facing antislope scarps in the coast mountains southwest british columbia uphill facing scarps are examined at affliction creek a glacierized area within the meager creek volcanic complex of southwest british columbia scarps occur directly downslope of tension cracks and are considered to have developed from a combination of 1 antithetic movement between partly toppled slices of rock defined by a master joint set dipping into the slope and 2 erosion of the upslope face of each tension crack leaving the downslope face prominent as an antislope scarp a kinematic test for toppling failure is described glacial erosion and rapid glacial downwasting are probable causes of toppling lichenometric data indicate significant scarp development since affliction glacier attained its maximum neoglacial dimensions about 140 yr ago dilatancy is cited as a possible mechanism for scarp stabilization

prediction of residual oil saturation by using the ratio of amplitude attributes of time lapse seismic data abstractsubtraction of baseline and monitoring seismic data is a common step in highlighting reservoir changes in time lapse seismic interpretation however ambiguity exists in the interpretation of the amplitude difference which is controlled by fluid change and reservoir thickness to estimate the residual oil saturation quantitatively we have developed a time lapse seismic interpretation method that uses the ratio of amplitude attributes extracted from the baseline and monitoring seismic data the relationship between impedance change and the ratio of the baseline and monitoring amplitude attributes is determined to avoid the influence of reservoir thickness subsequently the fluid saturation is calculated from the impedance change by using a proper petrophysical relationship we have tested our new method on a real time lapse seismic data set from a water flooded reservoir in the deepwater area of west africa the water flooded area determined from the amplitude difference does not completely matc

fast repeat modelling of time lapse seismograms in order to plan surveys for seismic time lapse studies seismograms are usually simulated for a set of earth models corresponding to different stages of the oil production process this can be expensive because for reasons of accuracy finite difference fd modelling is very often applied we present the born repeat modelling technique brm which is a combination of fd modelling and perturbation theory production effects are considered as small perturbations of the earth model and the born approximation is used to compute the change in the wavefield due to production induced modifications to the reservoir properties this is very efficient in the situation described above we give a detailed description of the proposed modelling scheme and discuss its applicability the theoretical foundations of brm are presented for onshore seismic experiments and an extension to the case of marine pressure seismograms is derived in addition the performance of brm is demonstrated with several numerical examples

the landslide response of alpine basins to post little ice age glacial thinning and retreat in southwestern british columbia abstract the role of post little ice age lia neoglacial retreat on landslide activity is investigated in 19 alpine basins along the upper lillooet river valley british columbia we examine how neoglacial scouring and glacial recession have modified hillslope form and slope stability and construct a decision making flowchart to identify landslide hazards associated with glacial retreat this work is based on field mapping gis analysis statistical associations between landslides and terrain attributes and a comparison between neoglaciated and non neoglaciated terrain within each basin the bedrock landslide response to glacial retreat varies appreciably according to lithology and the extent of glacial scour below the lia trimline valleys carved in weak quaternary volcanics show significant erosional oversteepening and contain deep seated slope movement features active rock fall rock slides and rock avalanches near glacial trimlines basins in stronger granitic rock rarely show increased bedrock instability resulting from post lia retreat except for shallow seated rock slides along some trimlines and failures on previously unstable slopes in surficial materials landslides associated with post lia retreat originate in till or colluvium as debris slides or debris avalanches and are concentrated along lateral moraines or glacial trimlines significant spatial association was also observed between recent catastrophic failures gravitational slope deformation and slopes that were oversteepened then debuttressed by glacial erosion eight out of nine catastrophic rock slope failures occurred just above glacial trimlines and all occurred in areas with a previous history of deep seated gravitational slope movement implying that this type of deformation is a precursor to catastrophic detachment

deep seated gravitational slope deformations in the highest parts of the czech flysch carpathians evolutionary model based on kinematic analysis electrical imaging and trenching deep seated gravitational slope deformations dsgsds played an important role during the quaternary evolution of mountain ridges formed by anisotropic flysch rocks of the outer western carpathians owc four dsgsd affected ridges in the highest part of the czech sector of the owc have been subjected to multidisciplinary investigation involving mapping structural and kinematic analysis geoelectrical imaging trenching and dating all the studied dsgsds are strongly predisposed by regional structural fabric given by the intersection of bedding planes joint sets and faults performed research suggests high diversity of mechanisms leading to the origin of individual dsgsds the area of a single dsgsd can be affected by various types of movements such as sackung lateral spreading toppling or incipient sliding electrical imaging and trenching revealed that besides these mechanisms anisotropic flysch massifs formed by thick bedded sandstones are strongly exposed to subsurface opening of air filled voids related to widened crevices such a process is driven by deep seated creep and translational sliding of sandstone beds upon plastic claystones whose strength has been reduced to residual values of the angle of internal friction performed radiocarbon and osl dating revealed that some of the studied dsgsds originated in the holocene period particularly in the atlantic and subboreal chronozones

time lapse seismic reservoir monitoring time lapse seismic reservoir monitoring has advanced rapidly over the past decade there are currently about 75 active projects worldwide and more than 100 cumulative projects in the past decade or so the present total annual expenditures on 4 d seismic projects are on the order of 50 100 million us this currently represents a much smaller market than 3 d seismic but the use of 4 d seismic has grown exponentially over the past decade and is expected to continue to do so

time lapse monitoring of the duri steamflood a pilot and case study this article describes a successful 4 d seismic pilot project in duri field indonesia the site of the world s largest steamflood two baseline and six monitor 3 d seismic surveys were recorded over the same steam injection pattern between 1992 and 1995 seismic analysis thermal simulation and acoustic modeling show the engineering relevance of these data and provide new insights into the seismic response of reservoirs during active steamflooding analyses of the data demonstrate that for the duri steamflood the horizontal and vertical distribution of steam can be tracked over time

paraglacial gravitational deformations in the sw alps a review of field investigations 10be cosmogenic dating and physical modelling catastrophic deep seated landslides dsl are generally considered to be the result of large slope deformations also known as deep seated gravitational slope deformation dsgsd this paper aims to build a synthesis of multiple studies made in the tinee valley southern french alps to assess the geometrical kinematical mechanical and chronological relationships between these two gravitational processes at the scale of the valley data issued from geological geomorphological and 10be dating indicate a clear geometrical link between dsgsd and dsl occurring at the base of the slope and suggest that gravitational slope evolution began after the glacial retreat 13 ka bp this is supported by the example of the well documented la clapiere slope a continuous evolution process is characterized geometrically and temporally from geomorphic observations and analogue modelling coupling structural geomorphological physical and chronological studies allowed us to propose a four dimensional 4d deformation model mechanically correlated with progressive failure concept the validity and variability of this reference site are discussed at the valley scale taking isola and le pra slope deformation as examples it allows a rough estimation of the state of slope deformation at the valley scale to be constructed and the slope evolution with time to be considered this 4d model could then be considered as a reference for other deep seated gravitational slope deformations in comparable alpine valleys

overburden complexity and repeatability of seismic data impacts of positioning errors at the oseberg field north sea repeatability of seismic data plays a crucial role in time lapse seismic analysis there are several factors that can decrease the repeatability such as positioning errors varying tide source variations velocity changes in the water layer marine data and undesired effects of various processing steps in this work the complexity of overburden structure as an inherent parameter that can affect the repeatability is studied a multi azimuth three dimensional vertical seismic profiling data set with 10 000 shots is used to study the relationship between overburden structure and repeatability of seismic data in most repeatability studies two data sets are compared but here a single data set has been used because a significant proportion of the 10 000 shots are so close to each other that a repeatability versus positioning error is possible we find that the repeatability decreases by a factor of approximately 2 under an overburden lens furthermore we find that the x and y components have approximately the same sensitivity to positioning errors as the z component for the same events in this three dimensional vertical seismic profiling experiment this indicates that in an area with complex overburden positioning errors between monitor and base seismic surveys are significantly more critical than outside such an area this study is based on a three dimensional three component vertical seismic profiling data set from a north sea reservoir and care should be taken when extrapolating these observations into a general four dimensional framework

rock slope deformation at affliction creek southern coast mountains british columbia a 7 year record of rock slope deformation is reported from affliction creek in the southern coast mountains of british columbia an estimated 3 107 m3 of monzonite basement and overlying garibaldi aged volcanic material is involved in a slow gravitational movement ground motion vectors suggest that movement has occurred along a deep seated shear zone and was accompanied by a downslope extension of the moving mass near surface flexural toppling producing antislope scarps has taken place where tension cracks crop out on steep slopes or wherever rock faces with strong planar jointing are glacially undercut structural data indicate the feasibility of both sliding and toppling at this site the stratigraphic evidence indicates that most of the tension cracks grabens and antislope scarps constituting the slope movement complex are less than 4300 years old and that many of these landforms may have developed quite recently as a result of rock slope debuttressing during the retreat of affliction glacier

a case history of time lapse 3d seismic surveys at cold lake alberta canada time lapse 3d seismic surveys were acquired across a bitumen field at cold lake alberta canada during a production cycle 1990 and a steam injection cycle 1992 of a thermal enhanced oil recovery eor program we observed changes in interval traveltime and amplitude distributions between the processed surveys we interpret the increased traveltimes observed over most of the injection survey to be a result of lowered interval velocities in the reservoir caused primarily by higher temperature and lower effective pressure reflection strength variations within the reservoir are present in each data set and change spatially between the surveys in general we interpret the amplitude anomalies seen only on the production survey to be caused by local free gas and the amplitude anomalies seen only on the injection survey which are close to the perforation depths to be caused by thin vertically restricted steamed zones

valley shape influence on deformation mechanisms of rock slopes stress distribution in mountainous areas is influenced by local morphology valley morphology and the relationship between main and tributary valleys strongly depend on geological characteristics and evolution they may control the evolution of slope instabilities especially when interacting with pervasive structural features we performed parametric three dimensional 3d numerical modelling of simplified slope geometries with variable slope angle from 218 to 358 length combining different orientations for different slope sectors and changing attitude of pervasive planes of anisotropy foliation schistosity bedding data used in the 3d models are the initial slope geometry rock mass properties and internal anisotropy we assumed mohr coulomb behaviour with the presence of ubiquitous joints and different piezometric levels the model results show that plastic deformation initiates near the highest ridge just after deglaciation commences a shear zone develops and propagates toward the toe of the slope and its shape is strongly controlled by slope geometry anisotropy and in situ stresses the thickness of the failing mass for model slope reliefs up to 3200 m increases from 50 mto some hundreds of metres during glacier retreat and it depends on geometry of slopes anisotropy and in situ stresses results are compared to examples of deep seated slope deformations from the alps which helps in the interpretation of such phenomena and in the understanding of their influence on valley evolution

quantified time scale for glacial valley cross profile evolution in alpine mountains space is used as a proxy for time in determining the role of glaciation in shaping valley cross profiles in the two thumb range southern alps new zealand the range is undergoing rapid tectonic transport and uplift as it is advected toward the alpine fault repeated cycles of glacial erosion during the quaternary have fashioned u shaped valleys in the north of the range close to the main divide while valleys in the less glaciated south of the range have rounded divides and convex fluvial cross profiles tectonic transport and uplift rates coupled with an offshore oxygen isotope 18o record and glacial geological reconstructions allow time constraints to be applied to valley development along the range valley width and depth measurements and power law equations were used to quantify the shape of cross profile transects in 37 valleys valleys evolved into a characteristic u shaped cross profile formed over 400 k y of glacial occupancy this regardless of other models of glacial flattening of valley long profiles suggests that alpine glaciation excavates greater volumes of rock indicating that glaciers are a more effective erosional agent than fluvial activity in alpine mountain belts

age evaluation and causation of rock slope failures along the western margin of the antrim lava group alg northern ireland based on cosmogenic isotope 36cl surface exposure dating the temporal pattern of postglacial rock slope failure in a glaciated upland area of ireland the western margin of the antrim lava group was evaluated using both 36cl exposure dating of surface boulders on run out debris and 14c dating of basal organic soils from depressions on the debris the majority of the 36cl ages 21 15 ka indicate that major failures occurred during or immediately following local deglaciation 18 17 ka other ages 14 9 ka suggest some later smaller scale failures during the lateglacial and or early holocene the 14c ages 2 36 0 15 cal ka bp indicate the very late onset of organic accumulation and do not provide close limiting age constraints rock slope failure during or immediately following local deglaciation was probably in response to some combination of glacial debuttressing slope steepening and paraglacial stress release later failures may have been triggered by seismic activity associated with glacio isostatic crustal uplift and or permafrost degradation consequent upon climate change the 36cl ages support the findings of previous studies that show the deglacial lateglacial period in northwest ireland and scotland to have been one of enhanced rock slope failure

sediment flux from a mountain belt derived by landslide mapping in humid uplands landsliding is the dominant mass wasting process in the western southern alps of new zealand landslides are scale invariant and have a power law magnitude frequency distribution independent studies from other regions suggest that this is a general property of landsliding this observation is of critical importance to the evaluation of the impact of events of different length scales over different time intervals on landscape evolution it is particularly useful when estimating regional geomorphic rates because it constrains the frequency and overall significance of extreme events which cannot otherwise be evaluated by integrating the complete response of the system we estimate the regional denudation rate due to landsliding to be 9 4 mm yr 1 sediment discharge from the western southern alps is dominated by landslide derived material

cosmogenic 10be dating of a sackung and its faulted rock glaciers in the alps of savoy france sackungs are the largest gravitational deformation observed in mountains they are characterized by the long term slowness of the movements but their mechanism is still not well understood nowadays cosmic ray exposure cre dating methods allow dating the morphologic structures involved in sackung and can contribute at the understanding of their origin in the alps the 5 3 km long arcs sackung initiated during the activity of rock glaciers three samples from these faulted rock glaciers provide their first cre ages and show that at 2000 m elevation these block accumulations moved during the younger dryas and stopped in early holocene six 10be ages of fault scarps show that the arcs sackung lasted only a few thousand years and stopped at about 8462 432 10be yr they also reveal that deformation migrated upslope in agreement with a mechanism of flexural toppling of vertical layers this unique and long gravitational event characterized by migration of the deformation does not support earthquake shaking as triggering mechanism for individual faults it shows that in the upper isere valley slope deformation was delayed of several thousand years after glacial debuttressing and is not anymore active despite its fresh morphology

green lake landslide and other giant and very large postglacial landslides in fiordland new zealand abstract green lake landslide is an ancient giant rock slide in gneiss and granodiorite located in the deeply glaciated fiordland region of new zealand the landslide covers an area of 45 km 2 and has a volume of about 27 km 3 it is believed to be new zealand s largest landslide and possibly the largest landslide of its type on earth it is one of 39 known very large 10 6 10 7 m 3 and giant 10 8 m 3 postglacial landslides in fiordland discussed in the paper green lake landslide resulted in the collapse of a 9 km segment of the southern hunter mountains slide debris moved up to 2 5 km laterally and 700 m vertically and formed a landslide dam about 800 m high impounding a lake about 11 km long that was eventually infilled with sediments geomorphic evidence supported by radiocarbon dating indicates that green lake landslide probably occurred 12 000 13 000 years ago near the end of the last otira glaciation the landslide is described and its geomorphic significance age failure mechanism cause and relevance in the region are discussed in relation to other large landslides and recent earthquake induced landslides in fiordland the slope failure occurred on a low angle fault zone undercut by glacial erosion and was probably triggered by strong shaking mm ix x associated with a large m 7 5 8 earthquake on the alpine fault c 80 km to the northwest geology was a major factor that controlled the style and size of green lake landslide and in that respect it is significantly different from most other gigantic landslides future large earthquakes on the alpine fault in fiordland are likely to trigger more very large and giant landslides across the region causing ground damage and devastation on a scale that has not occurred during the last 160 years with potentially disastrous effects on towns tourist centres roads and infrastructure the probability of such an event occurring within the next 50 years may be as high as 45

slope instability in relation to glacial debuttressing in alpine areas upper durance catchment southeastern france evidence from field data and 10be cosmic ray exposure ages the upper durance catchment is an area prone to rock slope failures such failures reflect the combination of high relief litho structural controls and paraglacial stress release the aim of this study is to determine the role of deglacial unloading and resulting paraglacial stress release in conditioning or triggering slope failure former dimensions of the durance glacier are reconstructed then combined with digital elevation model data in a raster geographic information system to quantify the spatial pattern of stresses associated with glacial loading at the last glacial maximum preliminary calculations suggest that major rock falls and rock avalanches are associated with areas subject to the highest decompression stresses focus on two case studies allows the consequences of paraglacial stress release on slope instability to be evaluated description of slope failure runout deposits allows reconstruction of the nature of slope failure surface exposure dates based on concentration of cosmogenic 10be allows the timing of both deglaciation and that of post glacial rock slope failures to be established it is shown that rock slope failures are concentrated on lower valley side slopes within the area occupied by ice at the last glacial maximum and that their locations coincide with zones of inferred high glacial loading stress consistent with interpretation of both bedrock disruption and large scale rock slope failures as paraglacial phenomena induced by stress release following deglaciation timing of initial rock avalanche runout deposition at one site is consistent with this conclusion though later instability episodes at the same site may have occurred independent of the influence of paraglacial stress release

temporal behavior of deep seated gravitational slope deformations a review abstract deep seated gravitational slope deformations dsgsds are slow moving hillslope scale mass movements featuring characteristic landforms such as double crested ridges and upslope facing scarps that occur in diverse landscapes throughout the world although these deformations have been studied since the 1960s significant insights to the rates of dsgsds have only been gained within the last two decades owing to progress in geochronology remote sensing and instrumental monitoring absolute age and monitoring data indicate that dsgsd movements are observable over long term 102 years and short term future research directions include constraining the lifespan of dsgsds with absolute age dating and precise high resolution monitoring of spatio temporal displacement across dsgsd bodies it is of great importance to include absolute time scales in the numerical models of dsgsds furthermore combining remote sensing techniques such as synthetic aperture radar interferometry with high resolution lidar scanning and near surface geophysics offers a promising toolkit for collecting very detailed and accurate data on the short term deformation rates of dsgsds

burying receivers for improved time lapse seismic repeatability co2crc otway field experiment 4d seismic is widely used to remotely monitor fluid movement in subsurface reservoirs this technique is especially effective offshore where high survey repeatability can be achieved it comes as no surprise that the first 4d seismic that successfully monitored the co2 sequestration process was recorded offshore in the sleipner field north sea in the case of land projects poor repeatability of the land seismic data due to low s n ratio often obscures the time lapse seismic signal hence for a successful on shore monitoring program improving seismic repeatability is essential stage 2 of the co2crc otway project involves an injection of a small amount around 15 000 tonnes of co2 ch4 gas mixture into a saline aquifer at a depth of approximately 1 5 km previous studies at this site showed that seismic repeatability is relatively low due to variations in weather conditions near surface geology and farming activities in order to improve time lapse seismic monitoring capabilities a permanent receiver array can be utilised to improve signal to noise ratio and hence repeatability a small scale trial of such an array was conducted at the otway site in june 2012 a set of 25 geophones was installed in 3mdeep boreholes in parallel to the same number of surface geophones in addition four geophones were placed into boreholes of 1 12m depth in order to assess the gain in the signal to noise ratio and repeatability both active and passive seismic surveys were carried out the surveys were conducted in relatively poor weather conditions with rain strong wind and thunderstorms with such an amplified background noise level we found that the noise level for buried geophones is on average 20 db lower compared to the surface geophones the levels of repeatability for borehole geophones estimated around direct wave reflected wave and ground roll are twice as high as for the surface geophones both borehole and surface geophones produce the best repeatability in the 30 90 hz

large sackung along major tectonic features in the central italian alps deep seated gravitational slope deformation sackung is common in alpine mountain belts it is controlled by lithological geomorphological and structural features we describe and discuss five examples of dsgsd along the insubric line periadriatic fault in the central italian alps the five examples are different in morphology size state of activity and distribution and are located along both primary and secondary valleys we demonstrate relations between structural and gravitational features and discuss the possibility that structural has both passive and active roles in sackung development analysis of ps sar data shows that the studied examples are not active today numerical modelling demonstrates the importance of lithological and structural constraints postglacial debuttressing groundwater fluctuations and weathering on sackung triggering and development

seismic properties of heavy oils measured data seismic techniques hold great potential for characterization and recovery monitoring of heavy oil reservoirs however to be more effective we must understand the seismic properties of the heavy oils and the heavy oil sands because this knowledge of in situ properties is key to linking the seismic response to reservoir properties and changes in this article we examine the seismic properties of heavy oils in detail

heavy oils their shear story heavy oils are important unconventional hydrocarbon resources with huge reserves and are usually exploited through thermal recovery processes these thermal recovery processes can be monitored using seismic techniques shear wave properties inparticular areexpectedtobemostsensitivetothechanges in the heavy oil reservoir because heavy oils change from being solid like at low temperatures to fluid like at higher temperatures to understand their behavior we measure the complex shearmodulusandthusalsotheattenuationofaheavy oil saturated rock and the oil extracted from it within the seismic frequency band in the laboratory the modulus and quality factor qoftheheavy oil saturatedrockshowamoderatedependence on frequency but are strongly influenced by temperature the shear wave velocity dispersion in these rocks is significant at steam flooding temperatures as the oil inside the reservoir loses viscosity atroomtemperatures theextractedheavyoilsupports a shear wave but with increasing temperature its shear modulus decreases rapidly which translates to a rapid drop in the shear modulus of the heavy oil saturated rock as well at these low to intermediate temperatures 30 c 100 c an attenuation peak corresponding to the viscous relaxation of the heavy oil is encountered also resulting in significant shear wave velocity dispersion well described by the cole cole model thus shearwaveattenuationinheavy oilrockscanbesignificantlylargeand iscausedbyboththemeltingandviscousrelaxationoftheheavy oil at yet higher temperatures the lighter components of the heavy oil are lost making the oil stiffer and less attenuative the dramaticchangesinshearvelocitiesandattenuationinheavyoils should be clearly visible in multicomponent seismic data and suggestthatthesemeasurementscanbequalitativelyandquantitatively used in seismic monitoring of thermal recovery processes

water flow through temperate glaciers understanding water movement through a glacier is fundamental to several critical issues in glaci ology including glacier dynamics glacier induced floods and the prediction of runoff from glacierized drainage basins to this end we have synthesized a conceptual model of water movement through a temper ate glacier from the surface to the outlet stream pro cesses that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology where a glacier is covered by a layer of porous perme able firn the accumulation zone the flux of water to the glacier interior varies slowly because the firn tempo rarily stores water and thereby smooths out variations in the supply rate in the firn free ablation zone in con trast the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time water moves from the surface to the bed through an upward branching arborescent net work consisting of both steeply inclined conduits formed by the enlargement of intergranular veins and gently inclined conduits spawned by water flow along the bottoms of near surface fractures crevasses engla cial drainage conduits deliver water to the glacier bed at a limited number of points probably a long distance downglacier of where water enters the glacier englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn their size adjusts so that they are usually full of water and flow is pressurized in contrast water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms flow is otherwise in an open channel configuration the subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically an up glacier branching arborescent network of channels in cised into the basal ice conveys water rapidly much of the water flux to the bed probably enters directly into the arborescent channel network which covers only a small fraction of the glacier bed more extensive spatially is a nonarborescent network which commonly includes cav ities gaps between the glacier sole and bed channels incised into the bed and a layer of permeable sediment the nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system the arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network the volume of water stored by a glacier varies diurnally and seasonally small temper ate alpine glaciers seem to attain a maximum seasonal water storage of 200 mm of water averaged over the area of the glacier bed with daily fluctuations of as much as 20 30 mm the likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes so most water storage may actually occur englacially stored water may also be released abruptly and catastrophically in the form of outburst floods

large ice contact slope movements glacial buttressing deformation and erosion glaciers and slope movements may act simultaneously to erode and modify glaciated slopes undercutting by glaciers can destabilize slopes but the extent to which slope failure may progress prior to subsequent glacier withdrawal has not hitherto been considered the traditional view has been that the buttressing effect of ice prevents slope movement the problem with this view is that ice is one third the density of rock and flows under low applied stress consequently failed slopes may move into the glacier if they exert a stress in excess of the resistance provided by the glacier slope movement rate depends on ice rheology and other factors influencing driving and resisting stresses simple viscous equations are used to investigate these variables the equations predict that small 108 m3 rockslides to test these estimates field evidence is presented of slope movements in glaciated valleys of new zealand narrowing or squeezing of glaciers adjacent to unstable rock slopes is demonstrated and considered to be the result of slope movement for one site geomorphic mapping and slope movement monitoring data show that movement rates are of similar order of magnitude to those predicted by the viscous equations closer agreement could be achieved with the application of modelling techniques that can more realistically model the complex slope geometries and stability factors encountered or by obtaining additional empirical data to calibrate the models this research implies that while the concept of glacial debuttressing the reduction of slope support from withdrawal of glaciers is valid complete debuttressing is not a prerequisite for the movement of ice contact rock slopes these slope movements may contribute to the erosional processes of glaciers and the evolution of glaciated slopes in a previously unrecognized way copyright 2012 john wiley sons ltd

time lapse seismic data registration and inversion for co2 sequestration study at cranfield abstractthe time lapse seismic survey for co2 sequestration study at cranfield can be problematic because of misalignments between time lapse data sets such misalignments can be caused by the seismic data processing workflow and may result in the wrong interpretation of time lapse seismic amplitude differences we propose an efficient local correlation based warping method of registering the time lapse poststack data sets which can align these data sets without changing original amplitudes application of our registration method to cranfield time lapse data demonstrates its effectiveness in separating time shift character from seismic amplitude signature after registration time lapse differences show an improved consistency in vertical cross sections and a more localized distribution of difference amplitudes along the horizon allowing us to apply a high resolution basis pursuit inversion bpi for acoustic impedances inversion results show that decreases in acoustic impedances occur mostly at the to

tectonic vs gravitational morphostructures in the central eastern alps italy constraints on the recent evolution of the mountain range abstract deep seated gravitational slope deformations dsgsds influence landscape development in tectonically active mountain ranges nevertheless the relationships among tectonics dsgsds and topography are poorly known in this paper the distribution of dsgsds and their relationships with tectonic structures and active processes surface processes and topography were investigated at different scales over 100 dsgsds were mapped in a 5000 km2 sector of the central eastern alps between the valtellina engadine and venosta valleys detailed lineament mapping was carried out by photo interpretation in a smaller area about 750 km2 including the upper valtellina and val venosta fault populations were also analysed in the field and their mechanisms unravelled allowing to identify different structural stages the youngest being consistent with the regional pattern of the ongoing crustal deformation finally four dsgsd examples have been investigated in detail by geological and 2d geomechanical modelling dsgsds affect more than 10 of the study area and mainly cluster in areas where anisotropic fractured rock mass and high local relief occur their onset and development is subjected to a strong passive control by mesoscopic and major tectonic features including regional nappe boundaries as well as nw se n s and ne sw trending recent brittle structures the kinematic consistency between these structures and the pattern of seismicity suggests that active tectonics may force dsgsds although field evidence and numerical models indicate slope debuttressing related to deglaciation as a primary triggering mechanism

failure forecast for large rock slides by surface displacement measurements forecasting the failure of large rock slides is difficult because of nonlinear time dependency and seasonal effects which affect the displacements starting from the accelerating creep theory prop

using a pseudo steady state flow equation and 4d seismic traveltime shifts for estimation of pressure and saturation changes abstractpressure and saturation changes cause a change in seismic p wave velocity resulting in a shift in 4d traveltime a discrimination between both effects is important to enhance reservoir management decisions we explored the possibility of linking the fields of reservoir engineering and 4d seismic a simple inversion scheme based on a reservoir engineering flow equation for pore pressure predictions combined with the hertz mindlin and gassmann rock physics models to discriminate pressure and saturation effects from 4d time shifts was presented to account for no flow reservoir boundaries the pseudo steady state flow equation giving the pressure distribution was extended with a superpositioning method during the inversion three parameters were determined by a nonlinear least squares fitting method the thickness of the hydrocarbon column the pressure at the well position and its decay rate away from the well we successfully tested our approach on a synthetic and a field data case where the co

recent advances in understanding ice sheet dynamics abstract glaciers and ice sheets play a dynamic role in earth s climate system influencing regional and global scale climate and responding to climate change on time scales from years to millennia they are also an integral part of earth s landscape in alpine and polar regions where they are an active agent in isostatic tectonic and earth surface processes this review paper summarizes recent progress in understanding and modelling ice sheet dynamics from the microphysical processes of ice deformation in glaciers to continental scale processes that influence ice dynamics based on recent insights and research directions it can be expected that a new generation of ice sheet models will soon replace the current standard improvements that can be foreseen in the near future include i the addition of internally consistent evolutionary equations for ice crystal fabric anisotropic flow laws ii more generalized flow laws that include different deformation mechanisms under different stress regimes iii explicit incorporation of the effects of chemical impurities and grain size dynamic recrystallization on ice deformation iv higher order stress solutions to the momentum balance stokes equation that governs ice sheet flow and v the continued merger of ice sheet models with increasingly complex earth systems models which include fully coupled subglacial hydrological and geological processes examples from the greenland ice sheet and vatnajokull ice cap iceland are used to illustrate several of these new directions and their importance to glacier dynamics

the tilt of the leading edge of mesoscale tropical convective lines abstract the tilt with height of the leading edge of seven mesoscale convective lines in gate is determined by two independent methods when averaged over time and along the line axis the tilt is found to he surprisingly shallow between 20 and 35 degrees from the horizontal this is distinct from the slopes of the individual towers which can be much steeper the line leading edge slope corresponds to the ratio of the vertical to horizontal velocity relative to the line motion of representative embedded convective cores