fungal proliferation at the cretaceous tertiary boundary we have found that a fungal spike occurs between the diverse late cretaceous palynoflora and the low diversity fern dominated early paleocene assemblages in a new zealand section the fungal layer is coincident with the ir anomaly marking the extinction event

dynamic processes of co2 storage in the field 1 multiscale and multipath channeling of co2 flow in the hierarchical fluvial reservoir at cranfield mississippi

time lapse 4 d seismic monitoring of primary production of turbidite reservoirs at south timbalier block 295 offshore louisiana gulf of mexico two seismic surveys acquired over south timbalier block 295 field offshore louisiana record significant differences in amplitude that are correlated to hydrocarbon production at multiple reservoir levels the k8 sand a solution gas drive reservoir shows increases in seismic amplitude associated with gas exsolution the k40 sand a water drive reservoir shows decreases in seismic amplitude associated with increases in water saturation a methodology is presented to optimize the correlation between two seismic surveys after they have been individually processed poststack this methodology includes rebinning crosscorrelation band pass filtering and cross equalization a statistical approach is developed to characterize the correlation between the seismic surveys this statistical analysis is used to discriminate seismic amplitude differences that record change in rock and fluid properties from those that could be the result of miscorrelation of the seismic data time lapse seismic analysis provides an important new approach to imaging hydrocarbon production it may be used to improve reservoir characterization and guide production decisions

bayesian time lapse inversion a new fast inversion approach for time lapse seismic data is developed where the uncertainty of the inversion results is an integral part of the solution the inversion method estimates changes in the elastic material properties of a reservoir because of production of hydrocarbons including uncertainty bounds on these estimates the changes in elastic properties then can be related to changes in hydrocarbon saturation and reservoir pressure by using rock physics relations the inversion operates directly on the difference between a repeat survey and a baseline survey this is advantageous with respect to the uncertainty calculation because an estimate of the seismic uncertainty can be obtained directly from the difference data in zones not affected by production the method is formulated in a bayesian setting and the solution is represented by explicit expressions for the posterior expectation and the covariance of the elastic parameter changes the explicit analytical form of the posterior distributi

a methodology for 7d warping and deformation monitoring using time lapse seismic data a methodology is presented for vector analysis of the image displacements warping between successive 3d seismic image volumes that provides 7d analysis including lateral and vertical displacements of in situ subsurface deformation around hydrocarbon reservoirs the key challenges are 1 assessment of just vertical shifts is insufficient and vector displacements should be determined 2 robust vertical displacements can usually be derived but lateral shifts are less well defined because of the generally smooth data character in a horizontal horizon plane 3 subvoxel resolution is necessary for correct matching and deformation analysis 4 velocity and strain effects are intrinsically combined in time lapse seismic images 5 separation of accumulated and local effects is necessary 6 apparently coherent and smooth displacement fields do not necessarily provide good strain analysis 7 warping is easily degraded by noise and good cross matching is a prerequisite to address these challenges a full 3d local warp vector derivation methodology is proposed which involves 1 constraint using prior estimates 2 local refinement with subvoxel resolution and 3 3d and vectorial conditioning using a deformable mesh with sensitivity to image match quality the warping approach is extended to separate accumulated from local effects and to analyze in situ deformation based on the displacement vector volume this is achieved by a finite element approach to determine an elemental pseudostrain tensor field and an iterative procedure to separate the pseudostrain into velocity and strain components the approach up to the strain analysis is demonstrated using a real data example which indicates the potential of the methodology accumulated overburden effects are separated to reveal a local compaction signature in the reservoir but realistic quantitative values of strain have not yet been realized

tsunami history of an oregon coastal lake reveals a 4600 yr record of great earthquakes on the cascadia subduction zone bradley lake on the southern oregon coastal plain records local tsunamis and seismic shaking on the cascadia subduction zone over the last 7000 yr thirteen marine incursions delivered landward thinning sheets of sand to the lake from nearshore beach and dune environments to the west following each incursion a slug of marine water near the bottom of the freshwater lake instigated a few year to several decade period of a brackish 4 salinity lake four additional disturbances without marine incursions destabilized sideslopes and bottom sediment producing a suspension deposit that blanketed the lake bottom considering the magnitude and duration of the disturbances necessary to produce bradley lake s marine incursions a local tsunami generated by a great earthquake on the cascadia subduction zone is the only accountable mechanism extreme ocean levels must have been at least 5 8 m above sea level and the cumulative duration of each marine incursion must have been at least 10 min disturbances without marine incursions require seismic shaking as well over the 4600 yr period when bradley lake was an optimum tsunami recorder tsunamis from cascadia plate boundary earthquakes came in clusters between 4600 and 2800 cal yr b p tsunamis occurred at the average frequency of 3 4 every 1000 yr then starting 2800 cal yr b p there was a 930 1260 yr interval with no tsunamis that gap was followed by a 1000 yr period with 4 tsunamis in the last millennium a 670 750 yr gap preceded the a d 1700 earthquake and tsunami the a d 1700 earthquake may be the fi rst of a new cluster of plate boundary earthquakes and accompanying tsunamis local tsunamis entered bradley lake an average of every 390 yr whereas the portion of the cascadia plate boundary that underlies bradley lake ruptured in a great earthquake less frequently about once every 500 yr therefore the entire length of the subduction zone does not rupture in every earthquake and bradley lake has recorded earthquakes caused by rupture along the entire length of the cascadia plate boundary as well as earthquakes caused by rupture of shorter segments of the boundary the tsunami record from bradley lake indicates that at times most recently 1700 yr b p overlapping or adjoining segments of the cascadia plate boundary ruptured within decades of each other

spatial thickness variability of the 2011 tohoku oki tsunami deposits along the coastline of sendai bay abstract soon after the 2011 tohoku oki event approximately 1300 tsunami deposit thickness data were collected spatially by the governors to cover the entire tsunami affected area sendai plain along the sendai bay coastline this dataset along with high resolution and high precision data of flow depth and pre tsunami and post tsunami elevation enables us first to conduct a direct comparison of the sedimentation and erosion volumes as well as the tsunami hydrodynamic features e g flow depth and sediment thickness the total balance of sedimentation and erosion volumes revealed that the volume of tsunami deposited sediments can be explained roughly using the erosion volumes at the beach and sand dunes for sandy deposits and at rice paddy fields for muddy deposits both the flow depth and sediment thickness showed positive correlations with the distance from the shoreline while sediment thickness is no correlation to the elevation except in the zone closest to the shoreline where erosion is present in addition a statistical relation was found between the flow depth and sediment thickness in fact the frequency distribution of sediment concentration defined here as the sediment thickness divided by the maximum flow depth at each survey site fits well with the logarithmic normal distribution with geometric average of about 2 this fit indicates that the tsunami deposits on the sendai plain can be explained generally if we simply assume that the saturated level of the sediment concentration in the flow is limited to about 2 on average irrespective of the grain size such a simple explanation might be applicable only for the tsunami deposits on the sendai plain because the topography is remarkably flat and low therefore the tsunami inundation process is relatively simple nevertheless a possible relation between tsunami flow depth and sediment thickness suggested here would be very useful to consider the ideal sedimentary process of the tsunami deposits and to improve forward and inverse modelings

4 d constrained depth conversion for reservoir compaction estimation application to ekofisk field ekofisk field in the norweigian sector of the north sea is a remarkable example of a strongly compacted chalk reservoir since the start of production in 1971 the water bottom has subsided by over 8 m as a result of reservoir compaction hermansen et al the field wide waterflood begun in 1989 was expected to halt pressure depletion and reservoir compaction after a few years of waterflooding ekofisk reservoir pressure began increasing but compaction and subsidence continued laboratory studies on chalk cores indicated that high porosity oil filled chalk compacts strongly when flushed with seawater these studies along with reservoir flow simulation and geomechanic modeling led to a model of a water weakening compaction sylte et al ongoing efforts deployed to monitor the reservoir compaction and seabed subsidence include twice a year compaction logging in a monitoring well daily gps measurements at the platforms and periodic bathymetry surveys nine surveys from 1970 to 1999

exploration methods lower tuscaloosa trend southwest mississippi abstract the unexpanded lower tuscaloosa formation is a major oil producer in southwest mississippi exploration of the lower tuscaloosa trend began in the mid forties with major fields being found on large uplifts and low relief structural noses today the trend is considered mature however the discoveries of several significant stratigraphically controlled fields since 1980 such as liberty millbrook olive and newtonia have renewed exploratory interest seismic stratigraphy is critical in exploration for stratigraphic reservoirs of this type sands can be predicted chiefly because of the low velocity of the reservoir sands relative to the enclosing higher velocity shales the environment of deposition of the lower tuscaloosa reservoir sands may be fluvial transitional marine or transgressive marine the geologic arguments for the various environments of deposition become moot as the erratic geometry of sand distribution is common to all these environments the projection of sand distributiuon away from well control without modern seismic data is very risky at best standard geologic exploration techniques such as sand isopachs and paleostructure maps are of limited value when looking for new fields in areas where well control is sparse or absent a structure map on the top of the lower tuscaloosa and a petrophysical sonic log understanding of the objective section top lower tuscaloosa marker to top lower cretaceous unconformity can lead to the discovery of additional small to medium sized stratigraphically trapped oil fields 1 7 million barrels of oil eeb s

the rise and demise of podozamites in east asia an extinct conifer life style abstract in the late triassic early jurassic forests dominated by podozamites an apparently deciduous shoot dropping conifer with broad multi veined leaves were extensive in what were the mid latitudes of eastern asia podozamites was the only conifer in many forests of this region and at times appeared to have formed an almost mono specific vegetation podozamites appears to have been little effected through the triassic jurassic transition but responded to climate changes later in the jurassic the chinese region progressively dried through the middle jurassic and aridity had developed in some areas by the late jurassic early cretaceous the centre of distribution of podozamites shifted north to the siberian region where conditions remained wet there it typically coexisted with conifers having a diverse range of smaller leaf morphologies by the late albian angiosperms had arrived in the siberian area and risen to dominance some time after this event podozamites became extinct this is significant as it represents the permanent extinction of a unique lifestyle a deciduous broad leaved and multi veined conifer the broad history of podozamites raises some interesting issues 1 the existence of a large dominantly deciduous vegetation at mid latitudes in the late triassic early jurassic is little discussed 2 it is unexpected that as broad leaved angiosperms took over amongst the conifers it was the broad leaved multi veined podozamites that became extinct this is the morphology that might have been expected to compete with the apparently more shade forming angiosperms instead it was the smaller leaved and single veined conifers that remained to coexist with the angiosperms

gas saturation prediction and effect of low frequencies on acoustic impedance images at foinaven field low frequencies are necessary in seismic data for proper acoustic impedance imaging and for petrophysical interpretation without lower frequencies images can be distorted leading to incorrect reservoir interpretation and petrophysical predictions as part of the foinaven active reservoir management farm project a towed streamer survey and an ocean bottom hydrophone obh survey were shot in both 1995 and 1998 the obh surveys contain lower frequencies than the streamer surveys providing a unique opportunity to study the effects that low frequencies have on both the acoustic impedance image along with petrophysical time lapse predictions artefacts that could easily have been interpreted as high resolution features in the streamer data impedance volumes can be distinguished by comparison with the impedance volumes created from the obh surveys containing lower frequencies in order to obtain results from the impedance volumes impedance must be related to saturation the mixing of exsolved gas oil and water phases involves using the reuss uniform or voigt patchy approximation mixing laws the voigt average is easily misused by assuming that the end points correspond to 0 and 100 gas saturation this implies that the patches are either 0 gas saturation or 100 gas saturation which is never the case here the distribution of gas as it comes out of solution is assumed to be uniform until the gas saturation reaches a sufficiently high value critical gas saturation to allow gas to flow therefore at low gas saturations the distribution is uniform but at saturations above critical it is patchy with patches that range from critical gas saturation to the highest gas saturation possible 1 minus residual oil and irreducible water saturation

petrology and depositional environments of lower tuscaloosa formation upper cretaceous sandstones in the north hustler and thompson field areas southwest mississippi abstract the lithology diagenesis and depositional environments of the dykes denkman and mccomb sands of the stringer sand member of the lower tuscaloosa formation in the north hustler and thompson field areas of amite county mississippi have been determined by detailed description of cores from nine wells and examination of 61 thin sections the cores were recovered from driller depths of about 11 100 ft in the updip tuscaloosa trend which is being actively explored for stratigraphically trapped oil most of the sandstone samples 65 are quartz arenites and the remainder are sublitharenites both types consist dominantly of fine to very fine grained sand the average sandstone consists of 67 3 framework grains 14 8 matrix 9 2 cement and 8 7 pore space monocrystalline quartz is by far the most abundant framework grain 88 7 with polycrystalline quartz 6 6 potassium feldspar 0 3 plagioclase 0 1 chert 1 9 igneous mostly volcanic rock fragments 0 5 metamorphic rock fragments 0 2 and sedimentary rock fragments 1 5 also present the matrix for the most part consists of pore filling clays and includes organic matter and secondary pyrite quartz and ferroan dolomite ankerite are the most common cements high concentrations of siderite and calcite occur as cement within some thin layers and siderite is also found commonly as small concretions porosity is mostly secondary resulting from partial dissolution of framework grains and cement quartz overgrowths probably formed during an early stage of diagenesis followed by deposition of calcite cement which corroded and embayed quartz and other framework grains apparently the calcite was later replaced by ankerite late stage pore filling clays include vermicular kaolinite and chlorite the latter occurring as rims and in dissolution enlarged pore space the depositional environment of the dykes and denkman sands in all wells is interpreted to be fluvial stacked point bars are obvious in one well the mccomb sand best developed in a wildcat well between thompson and mccomb fields is marine based on the occurrence of glauconite and shell fragments the presence of a basal scour surface on shale indicates that this sandstone may be the product of marine reworking of a transgressed distributary mouth bar

coastal lake sediments reveal 5500 years of tsunami history in south central chile abstract we present an exceptionally long and continuous coastal lacustrine record of 5500 years from lake huelde on the west coast of chiloe island in south central chile the study area is located within the rupture zone of the giant 1960 ce great chilean earthquake mw 9 5 the subsequent earthquake induced tsunami inundated lake huelde and deposited mud rip up clasts massive sand and a mud cap in the lake long sediment cores from 8 core sites within lake huelde reveal 16 additional sandy layers in the 5500 year long record the sandy layers share sedimentological similarities with the deposit of the 1960 ce tsunami and other coastal lake tsunami deposits elsewhere on the basis of general and site specific criteria we interpret the sandy layers as tsunami deposits age control is provided by four different methods 1 210pb dating 2 the identification of the 137cs peak 3 an infrared stimulated luminescence irsl date and 4 22 radiocarbon dates the ages of each tsunami deposit are modelled using the bayesian statistic tools of oxcal and bacon the record from lake huelde matches the 8 regionally known tsunami deposits from documented history and geological evidence from the last 2000 years without over or underrepresentation we extend the existing tsunami history by 9 tsunami deposits we discuss the advantages and disadvantages of various sedimentary environments for tsunami deposition and preservation e g we find that lake huelde is 2 3 times less sensitive to relative sea level change in comparison to coastal marshes in the same region

time lapse image registration using the local similarity attribute we present a method to register time lapse seismic images based on the local similarity attribute we define registration as an automatic point by point alignment of time lapse images stretching and squeezing a monitor image and computing its local similarity to the base image allows us to detect an optimal registration even in the presence of significant velocity changes in the overburden a by product of this process is an estimate of the ratio of the interval seismic velocities in the reservoir interval we illustrate the proposed method and demonstrate its effectiveness using both synthetic experiments and real data from a time lapse experiment in the duri field indonesia

late aptian palaeoclimatic turnovers and volcanism insights from a shallow marine and continental succession of the apennine carbonate platform southern italy abstract this study reports an integrated facies analysis carried out on a new section from the upper aptian of the se matese mts civitella licinio northern campania s italy which includes several decimeter to meter scale lacustrine intervals straddling a meter scale plant rich plattenkalk these intervals are assigned to the late gargasian early clansayesian by their stratigraphic relationship with the upper salpingoporella dinarica acme as well as lithologic and biostratigraphic supra regional key markers found in the apennine carbonate platform apcp including the orbitolina level we infer that the monogeneric parautochthonous plant remains frenelopsis sp were deposited in a supratidal to paralic coastal mudflat close to a restricted shallow marine lagoon at the verge of an arid semiarid climatic phase the plattenkalk was rapidly replaced by persistent lacustrine lithofacies at the onset of a major climatic turnover glacial trigger the overlying shallow marine deposits are capped by a deeply incised palaeokarstic surface and in turn by unconformable middle clansayesian transgressive shallow marine deposits interlayering of reliable lithologic indicators of palaeoclimate and high resolution event stratigraphic hires correlation of the civitella licinio succession with the astrochronologically tuned mt faito reference section of the apcp bring evidence of rapidly fluctuating hydroclimatic conditions wet and arid phases in the short 100 ky and long 400 ky eccentricity time band hires and astrochronological age assignment to crucial key markers and humid arid phases at civitella licinio permit to further refine the detailed stratigraphy of the mt faito reference section and to assign the upper s dinarica acme of the apcp to a numerical age of 118 55 118 50 my sem and eds analyses document common to abundant windblown volcanic particles glass shards and sanidine crystals throughout the frenelopsis rich plattenkalk 118 3 to 118 2 my and the encasing units especially in the overlying brackish lacustrine deposits palaeogeographic and palaeoclimatic reconstructions suggest that the pyroclastic material was probably transported by northeasterly trade winds from orogenic volcanic centers located within the dinaridic carpatho balkan arc trench system and have been supplied to the apcp for a time span of 3 my during the late aptian a preliminary tephrostratigraphic correlation of the upper aptian volcaniclastic levels of the apcp with the bentonite levels of the vocontian basin is proposed

late holocene covariability of the southern westerlies and sea surface temperature in northern chilean patagonia abstract the climate of chilean patagonia is strongly influenced by the southern westerlies which control the amount and latitudinal distribution of precipitation in the southern andes in austral summer the southern westerly wind belt swwb is restricted to the high latitudes it expands northward in winter which results in a strong precipitation seasonality between 35 and 45 s here we present a new precipitation seasonality proxy record from quitralco fjord 46 s where relatively small latitudinal shifts of the swwb result in large changes in precipitation seasonality our 1400 yr record is based on sedimentological and geochemical data obtained on a sediment core collected in front of a small river that drains the patagonian andes which makes this site particularly sensitive to changes in river discharge our results indicate fe al and ti al values that are low between 600 and 1200 ce increasing at 1200 1500 ce and high between 1500 and 1950 ce increasing fe al and ti al values reflect a decrease in mean sediment grain size from 30 to 20 m which is interpreted as a decrease in seasonal floods resulting from an equatorward shift of the swwb our results suggest that compared to present day conditions the swwb was located in a more poleward position before 1200 ce it gradually shifted towards the equator in 1200 1500 ce where it remained in a sustained position until 1950 ce this pattern is consistent with most precipitation records from central and southern chile the comparison of our record with published regional sea surface temperature sst reconstructions for the late holocene shows that equatorward shifts of the swwb are systematically coeval with decreasing ssts and vice versa which resembles fluctuations over glacial interglacial timescales we argue that the synchronicity between sst and swwb changes during the last 1400 years represents the response of the swwb to temperature changes in the southern hemisphere

cross equalization data processing for time lapse seismic reservoir monitoring a case study from the gulf of mexico nonrepeatable noise caused by differences in vintages of seismic acquisition and processing can often make comparison and interpretation of time lapse 3 d seismic data sets for reservoir monitoring misleading or futile in this gulf of mexico case study the major causes of nonrepeatable noise in the data sets are the result of differences in survey acquisition geometry and binning temporal and spatial amplitude gain wavelet bandwidth and phase differential static time shifts and relative mispositioning of imaged reflection events we attenuate these acquisition and processing differences by developing and applying a cross equalization data processing flow for time lapse seismic data the cross equalization flow consists of regridding the two data sets to a common grid applying a space and time variant amplitude envelope balance applying a first pass of matched filter corrections for global amplitude bandwidth phase and static shift corrections followed by a dynamic warp to align mispositioned events and finally running a second pass of constrained space variant matched filter operators difference sections obtained by subtracting the two data sets after each step of the cross equalization processing flow show a progressive reduction of nonrepeatable noise and a simultaneous improvement in time lapse reservoir signal

uncertainties in quantitative time lapse seismic analysis most seismic time lapse studies so far have been of a qualitative nature identification of areas with minor or no seismic changes has been used to plan new infill drilling targets increased accuracy in seismic acquisition methods in both conventional streamer surveys and newer methods such as multicomponent sea bed seismic and permanent sensors opens possibilities for the next step quantitative time lapse analysis quantitative methods here mean the estimation of for instance a change in fluid saturation from 20 water to 90 water or the estimation of a pore pressure change of 5 mpa explicit expressions for the uncertainties associated with estimated changes in for instance reservoir pressure and fluid saturation are derived these formulae can be used to compare relative uncertainties between estimated parameters as well as to identify the critical factors in various estimation techniques the importance of accurate rock physics input as well as that of highly repeatable time lapse seismic data is emphasized furthermore uncertainty analysis can be used to find optimal weight factors when the same parameter e g saturation change is estimated by two or three different techniques

discrimination between pressure and fluid saturation changes from time lapse seismic data explicit expressions for computing saturation and pressure related changes from time lapse seismic data have been derived and tested on a real time lapse seismic data set necessary input is near and far offset stacks for the baseline seismic survey and the repeat survey the method has been tested successfully in a segment where pressure measurements in two wells verify a pore pressure increase of 5 to 6 mpa between the baseline survey and the monitor survey estimated pressure changes using the proposed relationships fit very well with observations between the baseline and monitor seismic surveys 27 of the estimated recoverable hydrocarbon reserves were produced from this segment the estimated saturation changes also agree well with observed changes apart from some areas in the water zone that are mapped as being exposed to saturation changes which is unlikely saturation changes in other segments close to the original oil water contact and the top reservoir interface are also estimated and conf

tsunamis and tectonic deformation at the northern cascadia margin a 3000 year record from deserted lake vancouver island british columbia canada three layers of sand occur within a sequence of muddy gyttja in a 3 m core recovered from deserted lake which lies at the head of a fjord on the central west coast of vancouver island british columbia canada the sedimentology and microfossil assemblages of these layers are consistent with deposition by tsunamis radiocarbon ages suggest that the tsunamis were generated by plate boundary earthquakes at the cascadia subduction zone about 2600 1600 and 300 years ago diatom and protozoan contents of the gyttja layers indicate that relative sea level fell in the periods between tsunamis the sea level changes are probably a product of interseismic uplift of the north america plate margin post tsunami diatom and protozoan assemblages are generally more marine than their pre tsunami counterparts suggesting that the study site subsided during earth quakes estimates of interseismic and coseismic deformation during one earthquake cycle indicate that less than half of the interseismic uplift was recovered during the earthquake leading to cumulative or permanent uplift of the area

coastal evidence for holocene subduction zone earthquakes and tsunamis in central chile abstract the 500 year historical record of seismicity along the central chile coast 30 34 s is characterized by a series of m 8 0 8 5 earthquakes followed by low tsunamis 10 m but the frequency of such large events is unknown we extend the seismic history of central chile through a study of a lowland stratigraphic sequence along the metropolitan coast north of valparaiso 33 s at this site higher relative sea level during the mid holocene created a tidal marsh and the accommodation space necessary for sediment that preserves earthquake and tsunami evidence within this 2600 yr long sequence we traced six laterally continuous sand beds probably deposited by high tsunamis plant remains that underlie the sand beds were radiocarbon dated to 6200 5600 5000 4400 3800 and 3700 cal yr bp sediment properties and diatom assemblages of the sand beds for example anomalous marine planktonic diatoms and upward fining of silt sized diatom valves point to a marine sediment source and high energy deposition grain size analysis shows a strong similarity between inferred tsunami deposits and modern coastal sediment upward fining sequences characteristic of suspension deposition are present in five of the six sand beds despite the lack of significant lithologic changes between the sedimentary units under and overlying tsunami deposits we infer that the increase in freshwater siliceous microfossils in overlying units records coseismic uplift concurrent with the deposition of five of the sand beds during our mid holocene window of evidence preservation the mean recurrence interval of earthquakes and tsunamis is 500 years our findings imply that the frequency of historical earthquakes in central chile is not representative of the greatest earthquakes and tsunamis that the central chilean subduction zone has produced

late jurassic early cretaceous palynofloras in the lhasa block central xizang china and their bearing on palaeoenvironments abstract as a part of the qinghai xizang plateau the lhasa block has experienced a very complicated geological history since it rifted from gondwana little is known about how terrestrial ecosystems evolved on this block during this time our new materials collected from this block reveal for the first time the palaeovegetation and palaeoclimate during the late jurassic to early cretaceous three distinct palynological associations are recognized including the late jurassic cyathidites classopollis association and the early cretaceous berriasian barremian dicheiropollis and dicheiropollis peak associations an additional classopollis cooksonites association recovered from qubsang which lacks dicheiropollis is coeval with the dicheiropollis association these associations are generally similar to those on the qiangtang block southern qinghai province which indicates that these blocks had merged before the late jurassic facilitating establishment of a common palynoflora across the two blocks and adjacent regions the palaeovegetation on the lhasa block in the late jurassic was characterized by abundant tree ferns whereas during the earliest cretaceous cheirolepidiacean communities were more dominant within these communities a new cheirolepidiacean plant that produced dicheiropollis pollen emerged implying a potential increase in temperature the palaeoclimate was generally warm and semi humid during the late jurassic and early cretaceous although fluctuations of temperature and humidity occurred a reduction in precipitation from the lhasa block to the inland qiangtang block and tarim basin is reflected in the palynoflora a brief history of the vegetation and climate of the lhasa block from late jurassic to early cretaceous is provided

a method for estimating apparent displacement vectors from time lapse seismic images reliable estimates of vertical inline and crossline components of apparent displacements in time lapse seismic images are difficult to obtain for two reasons first features in 3d seismic images tend to be locally planar and components of displacement within the planes of such features are poorly resolved second searching directly for peaks in 3d crosscorrelations is less robust more complicated and computationally more costly than searching for peaks of 1d crosscorrelations i estimate all three components of displacement with a process designed to mitigate these two problems i address the first problem by computing for each image sample a local phase correlation instead of a local crosscorrelation i address the second problem with a cyclic sequence of searches for peaks of correlations computed for lags constrained to one of the three image axes

reconstructing paleoseismic deformation 1 modern analogues from the 1960 and 2010 chilean great earthquakes the 1960 and 2010 chilean great earthquakes provide modern analogues for the sedimentary signatures of the largest megathrust events and their accompanying tsunamis this paper presents lithological and diatom assemblage data from five sites and provides key insights for the development of longer earthquake chronologies essential for assessing the seismic hazards associated with a subduction zone we find that the 1960 and 2010 tsunami deposits are fragmentary variable and have no unique diagnostic diatom assemblage where rapid postseismic sedimentation occurs our diatom based transfer function model gives estimates of coseismic deformation that agree with independent estimates of land level change sedimentary hiatuses at two sites following the 2010 earthquake suggest that the magnitude of coseismic deformation may be underestimated in fossil records where sediment accumulation allows criteria for distinguishing between seismic and non seismic stratigraphies based on evidence for the largest plate boundary earthquakes are corroborated by the lesser magnitude earthquake of 2010 the key to reconstructing earthquake characteristics such as rupture magnitude and differences between plate boundary and upper plate sources depends on applying explicit stratigraphic assessment criteria at multiple sites in order to identify the spatial pattern of deformation associated with each earthquake

depositional features of co genetic turbidite debrite beds and possible mechanisms for their formation in distal lobated bodies beyond the base of slope ulleung basin east sea japan sea abstract a detailed analysis of the mr1 11 12 khz sonar images chirp 2 7 khz profiles core sediments and 14 c ages from the latest quaternary lobated bodies lb on the deep 2100 m water depth basin plain of the western ulleung basin reveals depositional features and context of co genetic turbidite debrite beds in the lb on the distal setting and a plausible mechanism for generating these beds eight lb are present in the basin plain ca 30 60 km beyond the base of slope and were generally deposited retrogressively older and more distal lb 1 4 have large dimensions 27 km long 15 25 km wide in contrast younger and less distal lb 5 8 are small 8 8 31 5 km long 1 2 12 km the muddier larger lb 1 and 2 were most likely originated from the relatively large scale sediment failures on the muddy upper slopes 350 400 m water depth between 18 5 and 20 0 cal ka b p on other hand the sandier smaller lb 6 and 7 were deposited between 17 0 and 17 5 cal ka b p probably by the relatively small scale sediment failures on the sandy uppermost slope shallower than 350 400 m water depth in lb 1 a lower sandy mud turbidite is transitional upward into an upper mud matrix debrite having small rounded mud clasts in contrast lb 6 exhibits a gradual upward change from a lower clay poor sandy turbidite to an upper clay rich sand matrix debrite with large interlocking mud clasts each mixed bed in lb 1 and 6 can represent a co genetic or linked turbidite debrite bed formed by the down dip flow transformation from turbidity current to debris flow at a point during the same event the abundant large scale up to 20 25 m deep 3 5 km long erosions of fine grained substrates near the base of slope area suggest that the down dip transformation was driven by incorporation of mud via erosional bulking by turbidity currents reaching the base of slope area the different clay sand content and size shape of mud clasts in the co genetic turbidite debrite beds between lb 1 and 6 imply that the composition sandy or muddy and dimension of initial turbidity current approaching the base of slope the volume of eroded masses from the fine grained substrates and the transport distance of sediment gravity flows from the erosional areas of muddy substrates can be all important factors controlling the depositional styles of co genetic turbidite debrite beds

tsunami sedimentary facies deposited by the storegga tsunami in shallow marine basins and coastal lakes western norway sedimentary successions in small coastal lakes situated from 0 to 11 m above the 7000 year bp shoreline along the western coast of norway contain a distinctive deposit very different from the sediments above and below the deposit is interpreted to be the result of a tsunami inundating the coastal lakes an erosional unconformity underlies the tsunami facies and is traced throughout the basins with most erosion found at the seaward portion of the lakes the lowermost tsunami facies is a graded or massive sand that locally contains marine fossils the sand thins and decreases in grain size in a landward direction above follows coarse organic detritus with rip up clasts here termed organic conglomerate and finer organic detritus the tsunami unit generally fines and thins upwards the higher basins 6 11 m above the 7000 year shoreline show one sand bed whereas basins closer to the sea level 7000 years ago may show several sand beds separated by organic detritus these alternations in the lower basins may reflect repeated waves of sea water entering the lakes in basins that were some few metres below sea level at 7000 years bp the tsunami deposit is more minerogenic and commonly present as graded sand beds but also in some of these shallow marine basins organic rich facies occur between the sand beds the total thickness of the tsunami deposit is 20 100 cm in most studied sites an erosional and depositional model of the tsunami facies is developed

palaeovegetation and palaeoclimate changes across the triassic jurassic transition in the sichuan basin china abstract the triassic jurassic transition interval is marked by enhanced biotic turnover rates in both marine and terrestrial realms however limited data from asia hampers the understanding of global ecosystem response to the end triassic mass extinction event here we present significant vegetation and climate changes across the triassic jurassic transition in the eastern tethys region southern china a detailed palynological study was performed from the qilixia section of the sichuan basin china spanning the upper triassic norian rhaetian xujiahe formation to the lower jurassic hettangian sinemurian lower zhenzhuchong formation five palynological assemblages reveal significant ecosystem fluctuations across the triassic jurassic transition our study indicates a lowland fern flora and a warm and humid climate in the late triassic norian to rhaetian interrupted by a cooler interval at the norian rhaetian transition and followed by a mixed mid storey forest under cooler and drier condition in the latest rhaetian this is followed by a fern dominated lowland vegetation and a warmer and drier climate during the triassic jurassic transition and a flora with abundant cheirolepid conifers in the hettangian sinemurian these long term changes in vegetation and inferred climatic conditions are comparable with records from the western tethyan realm and possibly reflect global terrestrial environmental changes associated with central atlantic magmatic province volcanism during the triassic jurassic transition

the application of diatoms to reconstruct the history of subduction zone earthquakes and tsunamis abstract earthquake and tsunami records on centennial and millennial temporal scales are necessary to understanding long term subduction zone behavior and the occurrences of large but infrequent events microfossils such as diatoms incorporated into coastal stratigraphy provide some of the most detailed reconstructions of the history of earthquakes and tsunamis we explore qualitative and quantitative techniques that employ the relation between diatoms and salinity tidal elevation and life form to 1 reconstruct records of vertical land level change associated with large earthquakes and 2 identify anomalous sand and silt beds deposited by tsunamis a global database shows that diatoms have been successfully employed in the reconstruction of earthquake and tsunami histories in chile the indian ocean japan new zealand the north sea the pacific northwest of north america and the south pacific we use case studies from some of these locations to highlight advancements in the field and new capabilities that diatoms have enabled examples from the pacific northwest of north america illustrate the evolution of quantitative diatom based reconstructions of earthquake related land level change in alaska and japan diatoms have documented land level changes throughout the earthquake deformation cycle including possible preseismic land level change signals and postseismic deformation diatoms helped identify coseismic uplift along the central chile subduction zone coast and uplift and subsidence along the alaska aleutian megathrust expanding our knowledge of the variability of slip in megathrust ruptures in tsunami studies diatoms help determine the provenance of anomalous sands and silts found in low energy coastal stratigraphic sequences in japan allochthonous marine and brackish diatoms within sand deposits signaled repeated marine incursions into a coastal lake helping identify a possible predecessor to the 2011 tohoku tsunami in the pacific northwest of north america and chile diatoms were used to estimate tsunami run up beyond the landward limit of tsunami sedimentation examples from the north sea thailand and japan show how the fragmentation and sorting of diatom valves may provide evidence of high energy transport during the rapid turbulent flow of a tsunami to conclude we emphasize the importance of studying the modern diatom response to changes in land level and or tsunami inundation to improve diatom based records of prehistoric earthquakes and tsunamis

space geodetic estimation of the nazca south america euler vector abstract gps data from four sites in the nazca plate easter island galapagos robinson crusoe and san felix islands and from five sites in the stable core of the south american plate enabled us to estimate the euler vector of the nazca plate with respect to south america the observed velocities of easter island 6 6 cm yr at 102 3 galapagos 5 1 cm yr at 90 0 robinson crusoe 6 6 cm yr at 80 1 and san felix 6 0 cm yr at 82 1 are significantly slower than the global plate model nuvel 1a velocites for those four sites our estimated euler pole is located at 48 8 n 91 7 w with a rate of 0 59 m y the nuvel 1a and earlier space geodetic studies give rotation rates that are 20 faster

plant taphonomy and palaeoecology in the lacustrine una delta late barremian iberian ranges spain abstract plant cuticle compressions and sporomorphs were studied in coaly clays belonging to the upper barremian la huerguina formation in una south western iberian ranges cuenca spain cuticle assemblages are extremely monotonous and formed by the genera frenelopsis schenk emend watson classostrobus alvin et al and glenrosa watson and fisher sporomorphs are dominated by classopollis pflug emend srivastava the genus glenrosa is described for the first time in europe sedimentological and taphonomical analyses show that these assemblages originated by fragmentation and size selection during residence in the leaf litter and by fluvial transport final deposition occurred in crevasse splay deltaic front and pro deltaic environments our results indicate that the una delta was fed almost exclusively by remains of cheirolepidiaceous conifers living in the upper deltaic plain of a lacustrine delta a comparison with the flora found in the open lacustrine facies of las hoyas which is laterally equivalent of the beds studied shows that land plant assemblages of las hoyas are more diverse the parautochthonous matoniaceous tree fern weichselia reticulata dominated the lakeshore vegetation of las hoyas in contrast to the vegetation of the upper delta plain of una which was dominated by frenelopsis the habitats of frenelopsis and glenrosa from the upper barremian oligohaline basin of una las hoyas contrast with the habitats commonly hypothesized for both taxa in coastal marine environments or on saline edaphic profiles in conclusion frenelopsis appears to have a wider tolerance to salinities than previously thought and their adaptations to saline edaphic conditions should be considered species specific rather than genus specific

late cretaceous campanian leaf and palynoflora from southern skane sweden a late cretaceous campanian leaf megaflora from the vomb trough in southern skane sweden has been investigated on the basis of collections held at the swedish museum of natural history the mai

impact of megathrust geometry on inversion of coseismic slip from geodetic data application to the 1960 chile earthquake 1 we analyze the role of megathrust geometry on slip estimation using the 1960 chile earthquake mw 9 5 as an example a variable slip distribution for this earthquake has been derived by barrientos and ward 1990 applying an elastic dislocation model with a planar fault geometry their model shows slip patches at 80 110 km depth isolated from the seismogenic zone interpreted as aseismic slip we invert the same geodetic data set using a finite element model fem with precise geometry derived from geophysical data isoparametric fem is implemented to constrain the slip distribution of curve shaped elements slip resolved by our precise geometry model is limited to the shallow region of the plate interface suggesting that the deep patches of moment were most likely an artifact of the planar geometry our study emphasizes the importance of fault geometry on slip estimation of large earthquakes

potential predecessors of the 2004 indian ocean tsunami sedimentary evidence of extreme wave events at ban bang sak sw thailand abstract where historical records are short and or fragmentary geological evidence is an important tool to reconstruct the recurrence rate of extreme wave events tsunamis and or storms this is particularly true for those coastal zones around the indian ocean where predecessors of similar magnitude as the 2004 indian ocean tsunami iot have not been reported by written sources in this context the sedimentary record of the holocene coastal plain of ban bang sak phang nga province thailand provides evidence of multiple prehistoric coastal flooding events in the form of allochthonous sand beds which were radiocarbon dated to 700 500 1350 1180 and younger than 2000 cal bp the layers were assigned to high energy events of marine origin which could be either tsunamis or tropical storms by means of granulometry geochemistry vertical structure and macrofossil content although no landfall of a strong storm has occurred in the last 150 years of meteorological data recording cyclones cannot be ruled out for the last centuries and millennia however discrimination between tsunami and storm origin was mainly based on the comparison of the palaeoevent beds with the local deposit of the iot which revealed similar characteristics in regard to spatial extend and sediment properties furthermore the youngest palaeoevent correlates with contemporaneous deposits from thailand and more distant coasts hence we relate it to a basin wide tsunami which took place 700 500 years ago for the sediments of older extreme events deposited between 2000 and 1180 cal bp we found no unambiguous counterparts at other sites nevertheless at least for now they are treated as tsunami candidates

erosion deposition and landscape change on the sendai coastal plain japan resulting from the march 11 2011 tohoku oki tsunami case studies of recent tsunami impacts have proven to be extremely useful in understanding the geologic processes involved during inundation and return flow and refining the criteria used to identify paleotsunami deposits in the geologic record here we report on erosion deposition and associated landscape change resulting from the march 11 2011 tohoku oki tsunami along a nearly 4 5 km shore normal transect on the coastal plain near sendai japan the study area on the broad low relief prograding coastal sendai plain comprised a sand beach backed by 3 m high sand dunes and a forest a wetland the teizan canal agricultural rice fields buildings and roads field observations focused on measurements of tsunami flow characteristics height and direction mapping of erosion features and assessing sediment deposition based on shallow trenches at 50 100 m spacing recorded tsunami inundation heights reached up to about 11 m above mean sea level within the first 500 m from the shoreline and then ranged between 3 and 5 m for the next 2 km gradually decreasing to about 3 m close to the inundation limit the tsunami deposit generally thinned landward from an average maximum 30 cm thick sand deposit in the coastal forest to a thin mud drape several mm thick near the inundation limit a discontinuous sand dominated sheet was prevalent to about 2800 m from the shoreline where mud content then gradually increased further landward eventually resulting in a mud dominated deposit ranging from 3 5 cm to a few mm thickness the overall thinning and fining of the deposit was often interrupted by localized features that led to complex sedimentological relationships over short distances satellite imagery taken on 14 march 2011 3 days after the tohoku oki tsunami shows prominent foreshore incisions with 100 s meters spacing alongshore a foredune ridge that underwent severe erosion and development of a prominent shore parallel elongated scour depression our field survey in early may 2011 revealed that the foreshore recovered quickly with rapid post tsunami sediment deposition from incident waves whereas the dune ridge complex had undergone only minor re working from eolian processes

cross matching with interpreted warping of 3d streamer and 3d ocean bottom cable data at valhall for time lapse assessment legacy streamer data and newer 3d ocean bottom cable data are cross matched and analysed for time lapse analysis of geomechanical changes due to production in the valhall field the issues relating to time lapse analysis using two such distinctly different data sets are addressed to provide an optimal cross matching workflow that includes 3d warping additionally an assessment of the differences between the imaging using single azimuth streamer and multi azimuth ocean bottom cable data is provided the 3d warping utilized in the cross matching procedure is sensitive to acquisition and processing differences but is also found to provide valuable insight into the geometrical changes that occur in the subsurface due to production as such this work also provides a demonstration of the use of high resolution 3d interpreted warping to resolve the 3d heterogeneity of the compaction and subsidence this is an important tool for valhall and possibly other fields where compaction and subsidence and monitoring thereof are key factors in the reservoir management since the predominant observed production induced changes are compaction of the soft high porosity chalk reservoir due to pore pressure reduction and the resultant overburden subsidence such reservoir compaction could have significant implications for production by changing permeabilities and production rates furthermore the subsidence effects could impact upon subsea installations and well bore stability geomechanical studies that have previously been used to model such subsidence and compaction are only constrained by observed surface displacements and measured reservoir pressure changes with the geological overburden being largely neglected the approaches suggested herein provide the potential for monitoring and assessment in three dimensions including the probable heterogeneity and shearing that is needed for full understanding of reservoir compaction and the resultant effects on the overburden to for example mitigate well bore failures

cretaceous patterns of floristic change in the antarctic peninsula cretaceous radiation of angiosperms from low to high palaeolatitudes coupled with the break up of gondwana played a major role in establishing and maintaining biogeographic patterns across the southern hemisphere uncertainties in details of plate reconstructions provide conflicting hypotheses about area relationships of gondwana fragments this has led to a number of competing proposals concerning angiosperm migration across gondwana central to this debate is the role of the antarctic peninsula a region that is often envisaged as providing the main connection between east and west gondwana the initial radiation of angiosperms into the antarctic peninsula region however postdates appearances elsewhere in east gondwana e g australia strongly suggesting that the antarctic peninsula was not the main gateway at least in the early stages of gondwana radiation a steep climatic gradient in this part of the world probably acted as an effective barrier to angiosperm radiation the peak of floristic replacement coincides with the peak of cretaceous warmth turonian which in turn suggests that climatic warming acted as a forcing mechanism by pushing latitudinal belts of vegetation southwards once into the southern high latitudes angiosperms diversified and as climates cooled during the late cretaceous a number of important groups seem to have their origins here recent investigations of antarctic macro and microfloras indicate progressive floristic replacement through the cretaceous bryophytes hepatophytes bennettites and other seed plants all show a rapid decline in diversity in contrast ferns initially decline then recover while conifers remain relatively stable the ecological preferences of the replaced groups imply that angiosperms initially occupied areas of disturbance and were understorey colonizers only later replacing fern thickets and becoming important in the overstorey this pattern is consistent with those observed elsewhere through the cretaceous

late early cretaceous climate and pco2 estimates in the liupanshan basin northwest china abstract the extinct conifer family cheirolepidiaceae especially pseudofrenelopsis is commonly used to reconstruct the atmospheric palaeo co2 concentration pco2 during the cretaceous period in recent years many pseudofrenelopsis specimens have been collected from the uppermost stratum of the naijiahe formation in the liupanshan basin ningxia hui autonomous region northwest china the stomatal parameters such as stomatal density stomatal index stomatal pore length and stomatal pore depth and the stable carbon isotope composition of the present pseudofrenelopsis were analyzed the palaeo co2 levels of the liupanshan basin during the late early cretaceous late albian were reconstructed using stomatal ratio sr and mechanistic model approaches the sr method yielded a semi quantitative pco2 estimate of 620 ppmv on the basis of the recent standardization and 1030 ppmv on the basis of the carboniferous standardization which show similarities with other sr based and geochemical based reconstructions for the late early cretaceous the pco2 was about 670 ppmv on the basis of mechanistic model method similar to the estimated pco2 values recovered by the sr method corrected with the recent standardization based on comparative studies of previously published pco2 results of the early cretaceous pco2 levels varied during the early cretaceous and pco2 was relatively stable during the late early cretaceous furthermore environmental conditions of the liupanshan basin during the late early cretaceous were studied the stable carbon isotope composition of pseudofrenelopsis leaves ranged from 21 5 to 24 3 with an average of 22 8 indicating an arid semi arid and high evaporation climate during the late early cretaceous in the liupanshan basin these environmental conditions were also supported by palynological lithological and geochemical evidence

a new terrestrial plant rich fossil lagerstatte from the middle cenomanian late cretaceous of the apennine carbonate platform magliano vetere southern italy depositional and palaeoenvironmental settings abstract we describe a new terrestrial plant rich fossil lagerstatte discovered at magliano vetere campania region s italy in the middle cenomanian of the apennine carbonate platform the deposit 1 42 m thick is made up of a thin bedded interlayering of evenly laminated dolomicrites lenticular dolorudites and carbonaceous seams which contain well preserved remains of terrestrial plants yielding cuticles and minor fishes this study focuses on plant remains to provide systematical taphonomical and palaeoenvironmental considerations nevertheless a preliminary analysis carried out on fossil fishes has led to the identification of pycnodontids and teleosts the fossil lagerstatte retains sterile foliage bearing shoots with epidermal features belonging to the genus frenelopsis of the extinct conifer family of the cheirolepidiaceae plant remains possibly represent a stable biotope as floral composition displays no variation along the deposit nevertheless episodes of harsh environmental conditions occurred as demonstrated by a fish mortality event and ca sulphate evaporite precipitation taphonomical considerations and sedimentological evidence from the encasing sediments suggest a parautochthonous deposition of fossil plants in a supratidal intertidal mudflat including a salt marsh that was characterised by a restricted sea water circulation deposition of primary dolomite and episodical wildfires the presence of xeromorphic features in frenelopsis from magliano vetere could represent an adaptation to haline environment which was subjected to microtephra supply from a distant orogenic volcanism the facies evolution of the studied fossil lagerstatte records a rapid regressive and a following slower transgressive trend and constitutes the lowermost portion of a 20 m thick interval characterised by several dolomitic plattenkalk up to 1 50 m thick which are separated by cyclically stacked peritidal limestones we infer that 1 the 20 m thick plattenkalk bearing interval represents a sequence boundary zone in the stratigraphical record of the middle cenomanian apcp 2 frenelopsis thrived at the verge of an arid semiarid climatical phase during a major pulse of relative sea level fall

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

cheirolepidiacean foliage and pollen from cretaceous high latitudes of southeastern australia cheirolepidiaceae leaves and pollen are recorded from valanginian albian strata of southeastern australia that were deposited at high latitudes under cool moist climates in contrast to the semi arid or coastal habitats preferred by many northern gondwanan and laurasian representatives of this group leaves of this family are characterized by thick cuticles and cyclocytic stomata with randomly oriented apertures arranged in scattered or longitudinal rows or bands stomata are deeply sunken and surrounded by four to six subsidiary cells that bear one or two ranks of prominent overarching papillae which may constrict the mouth of the pit three new taxa otwayia denticulata tosolini cheirolepidiaceae cuticle sp a and sp b are distinguished based on cuticular features adding to several previously documented cheirolepid conifers in the early cretaceous of eastern australia cheirolepidiaceae foliage is preserved predominantly in fluvial floodbasin settings and is interpreted to be derived from small trees occupying disturbed or low nutrient sites the foliage is associated with classopollis corollina pollen and roots characterized by prominent mycorrhizal nodules a cenomanian classopollis type recognised from bathurst island northern australia is recorded for the first time from the early cretaceous eumeralla formation otway basin classopollis locally is rare in valanginian barremian strata of boola boola gippsland but constitutes up to 14 of the palynomorph assemblage in albian strata this indicates that the family was locally abundant in cool southern high latitude climates of the mesozoic contrary to previous reports of its rarity in this region

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

five centuries of tsunamis and land level changes in the overlapping rupture area of the 1960 and 2010 chilean earthquakes a combination of geological and historical records from south central chile provides a means to address general questions about the stability of megathrust rupture patches and the range of variation expected among earthquakes and tsunamis along a particular stretch of a subduction zone the tirua river estuary 38 3 s records four large tsunamis and coseismic land level changes over the past 450 years within the overlapping rupture zones of the great subduction zone earthquakes of a d 1960 mw 9 5 and 2010 mw 8 8 sand layers 2 km up the tirua river represent the 2010 and 1960 tsunamis and two historical tsunamis most likely in a d 1751 and 1575 differing land level changes during these earthquakes likely denote differences in the spatial distribution of slip on the megathrust in both the strike and dip directions within the overlapping rupture zone with the uplift at tirua in 1751 and 2010 probably caused by slip extending farther landward and to greater depth than in 1575 and 1960 which showed subsidence or little change

4d signal enhancement using singular value decomposition application to mapping oil water contact movement across the nelson field a new method for time lapse signal separation and enhancement using singular value decomposition is presented singular value decomposition is used to separate a 4d signal into its constituent parts common geology time lapse response and noise synthetic tests which demonstrate the advantages of the singular value decomposition technique over traditional differencing methods are also presented this signal separation and enhancement technique is used to map out both the original and moved oil water contacts across the nelson field the singular value decomposition technique allows the oil water contact to be mapped across regions which would have been missed using traditional differencing methods in particular areas toward the edges of the field are highlighted by the technique the oil water contact is observed to move upwards across the field with the largest movements being associated as anticipated with natural production the results obtained are broadly consistent with those predicted by the reservoir simulator model singular value decomposition is demonstrated to be a useful tool for enhancing the time lapse signal and for gaining confidence in areas where traditional differencing fails

distribution and sedimentary characteristics of tsunami deposits along the cascadia margin of western north america abstract tsunami deposits have been found at more than 60 sites along the cascadia margin of western north america and here we review and synthesize their distribution and sedimentary characteristics based on the published record cascadia tsunami deposits are best preserved and most easily identified in low energy coastal environments such as tidal marshes back barrier marshes and coastal lakes where they occur as anomalous layers of sand within peat and mud they extend up to a kilometer inland in open coastal settings and several kilometers up river valleys they are distinguished from other sediments by a combination of sedimentary character and stratigraphic context recurrence intervals range from 300 1000 years with an average of 500 600 years the tsunami deposits have been used to help evaluate and mitigate tsunami hazards in cascadia they show that the cascadia subduction zone is prone to great earthquakes that generate large tsunamis the inclusion of tsunami deposits on inundation maps used in conjunction with results from inundation models allows a more accurate assessment of areas subject to tsunami inundation the application of sediment transport models can help estimate tsunami flow velocity and wave height parameters which are necessary to help establish evacuation routes and plan development in tsunami prone areas

diversity of the woody vegetation of gondwanan southern africa abstract the flora of gondwanan southern africa is represented in the rock record by micro fossils macro fossils and petrified woods all these types of fossils are seldom preserved together in any one particular facies because of taphonomic and preservational biases in order to obtain as accurate a picture as possible of the woody vegetation both the fossil woods and other macroplant fossils such as leaf impressions fructifications and cuticle of woody plants have been correlated this was done for each formation in the karoo supergroup in order to illustrate the changes in diversity of woody vegetation over time sediments of the karoo supergroup represent the terrestrial fossil record of the period upper carboniferous to the lower cretaceous when africa finally separated from south america in the upper carboniferous to lower permian dwyka formation there are at least five described genera of woods from south africa and namibia early to middle permian woods ecca group are a little more diverse with six genera representing the glossopterids cordaitaleans and possibly other seed fern groups late permian to early triassic beaufort group woods show very little change in diversity in spite of the major floral and biotic turnover evident from the rest of the fossil record although the late triassic molteno formation macro flora has been shown to be an example of explosive diversification the generally poorly preserved woods do not reflect this lower jurassic fossils clarens formation are also poorly preserved but have araucarian characteristics early cretaceous woods represent the araucariaceae cheirolepidiaceae and podocarpaceae with a number of species the diversity of the woods has not changed as much as the rest of the floral components in southern africa from the late carboniferous to the early cretaceous possible reasons for this apparent stasis are the conservative nature of wood functional restrictions limitations of suitable conditions for petrifications and the fact that very little research has been done on southern african woods

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

the glacial geomorphology and pleistocene history of south america between 38 s and 56 s abstract this paper presents new mapping of the glacial geomorphology of southern south america between latitudes 38 s and 56 s approximately the area covered by the former patagonian ice sheets glacial geomorphological features including glacial lineations moraines meltwater channels trimlines sandur and cirques were mapped from remotely sensed images landsat 7 etm pan sharpened landsat 7 and aster the landform record indicates that the patagonian ice sheets consisted of 66 main outlet glaciers together with numerous local cirque glaciers and independent ice domes in the surrounding mountains in the northern part of the mapped area in the chilean lake district 38 42 s large piedmont glaciers developed on the western side of the andes and the maximum positions of these outlet glaciers are in general marked by arcuate terminal moraines to the east of the andes between 38 s and 42 s outlet glaciers were more restricted in extent and formed alpine style valley glaciers along the eastern flank of the andes south of 45 s a series of large fast flowing outlet glaciers drained the ice sheet the location of these outlet glaciers was topographically controlled and there was limited scope for interactions between individual lobes west of the andes at this latitude there is geomorphological evidence for an independent ice cap close to sea level on the taitao peninsula the age of this ice cap is unclear but it may represent evidence of glacier growth during the antarctic cold reversal and or younger dryas chronozone maximum glacier positions are difficult to determine along much of the western side of the andes south of 42 s because of the limited land there and it is assumed that most of these glaciers had marine termini in the south east of the mapped area in the fuegan andes cordillera darwin the landform record provides evidence of ice sheet initiation by adding published dates for glacier advances from the literature we present maps of pre last glacial maximum lgm glacier extent lgm extent and the positions of other large mapped moraines younger than lgm in age a number of large moraines occur within the known lgm limits the age of these moraines is unknown but since many of them lie well outside the established maximum neoglacial positions the possibility that they reflect a return to glacial climates during the younger dryas chronozone or antarctic cold reversal cannot be discounted

coastal geomorphic conditions and styles of storm surge washover deposits from southern thailand abstract the characteristics of tropical storm washover deposits laid down during the years 2007 to 2011 along the southern peninsular coast of the gulf of thailand got were described in relation to their different geomorphic conditions including perched fan washover terrace and sheetwash lineations preserved behind the beach zone within 100 m of the shoreline as a result washover terrace and sheetwash lineations were found where the beach configuration was uniform and promoted an unconfined flow non uniform beach configurations that promoted a confined flow resulted in a perched fan deposit washover sediments were differentiated into two types based on sedimentary characteristics including i a thick bedded sand of multiple reverse grading layers and ii a medium bedded sand of multiple normal grading layers in the case of thick bedded washover deposits the internal sedimentary structures were characterized by the presence of sub horizontal bedding reverse grading lamination foreset bedding and wavy bedding whereas horizontal bedding normal grading and dunes were the dominant structures in the medium bedded washover sand rip up clasts were rare and recognized only in the washover deposits in the bottom unit which reflects the condition when a mud supply was available all washover successions were found in the landward inclined bedding with a basal sharp contact a high elevated beach ridge associated with a large swale at the backshore proved suitable for a thick bedded washover type whereas a small beach ridge with uniformly flat backshore topography promoted a medium bedded washover sediment

decay and expansion of the early aftershock activity following the 2011 mw9 0 tohoku earthquake the 2011 m w9 0 tohoku earthquake was followed by an abundant amount of seismicity providing a unique opportunity to analyze the triggering mechanism of great earthquakes although the tohoku earthquake occurred close to a dense seismic network many aftershocks that occurred in the first few hours after the mainshock are not recorded in the earthquake catalogs here we use a template waveform approach to recover as many as possible missing events in the first 12 hours following the tohoku mainshock our analysis is able to detect about 1 4 times more events than those listed in the high sensitivity seismograph hi net earthquake catalog combining our new dataset with earthquakes that occurred at latter times we are able to observe a continuous decay of the aftershock rate and along strike expansion of aftershock area we relate the latter observation to the occurrence of post seismic slip over the deep interface

the 2011 japan tsunami current velocity measurements from survivor videos at kesennuma bay using lidar 1 on march 11 2011 a magnitude mw 9 0 earthquake occurred off the coast of japan s tohoku region causing catastrophic damage and loss of life the tsunami flow velocity analysis focused on two survivor videos recorded from building rooftops at kesennuma bay along japan s sanriku coast a terrestrial laser scanner was deployed at the locations of the tsunami eyewitness video recordings the tsunami current velocities through the kesennuma bay are determined in a four step process the lidar point clouds are used to calibrate the camera fields of view in real world coordinates the motion of the camera during recordings was determined the video images were rectified with direct linear transformation finally a cross correlation based particle image velocimetry analysis was applied to the rectified video images to determine instantaneous tsunami flow velocity fields the measured maximum tsunami height of 9 m in the kesennuma bay narrows were followed by maximum tsunami outflow currents of 11 m s less than 10 minutes later

preservation potential of tsunami deposits on arid siliciclastic coasts abstract numerous post tsunami surveys have been conducted in the last two decades especially since the 2004 indian ocean tsunami these studies have documented a variety of characteristic sedimentary and erosional features that can be ascribed to known events nevertheless the question arises whether these structures are just ephemeral or have a potential to be preserved in the geological record this review describes the changes that have affected muddy to sandy siliciclastic tsunami deposits in peru each of these was surveyed in the first months after the tsunami chimbote 1996 camana 2001 and pisco paracas 2007 here we describe the changes we observed during re surveys in 2007 and 2008 it has long been recognized that onshore tsunami deposits may suffer from surficial processes tectonic movements and anthropogenic alteration earthquake induced uplift or subsidence may subject a tsunami deposit to erosion or burial respectively quick burial in rapidly subsiding coastal areas may enhance preservation deposits of the last or most landward reaching wave may be preferentially preserved if they escape erosion by subsequent tsunami waves however inland areas are also vulnerable to subaerial reworking including by wind and by humans the peruvian examples reviewed here show that the preservation of arid coast tsunami deposits depends on interactions that are more complex that hitherto perceived these involve sediment type grain size depositional setting co seismic movement bioturbation winds and anthropogenic modification in one example all traces of the tsunami have been removed or reworked by flash floods and ocean waves in another example clasts on a coastal plain from tsunami backwash began to be rounded and abraded by eolian sands immediately after the event eolian processes also smoothed and filled tsunami scours by contrast muddy tsunami deposits in certain areas escaped erosion by wind probably because of their greater cohesion in still another example 0 5 m of co seismic uplift was not enough to prevent ocean waves from removing a tsunami sand sheet that had mantled a coastal marsh the buried record of tsunami deposits on modern coasts may therefore not fully represent the vulnerability of these regions to tsunamigenic hazards

identifying coseismic subsidence in tidal wetland stratigraphic sequences at the cascadia subduction zone of western north america tidal wetland stratigraphy reveals that great plate boundary earthquakes have caused hundreds of kilometers of coast to subside at the cascadia subduction zone however determining earthquake recurrence intervals and mapping the coastal extent of past great earthquake ruptures in this region are complicated by the effects of many sedimentologic hydrographic and oceanographic processes that occur on the coasts of tectonically passive as well as active continental margins tidal wetland stratigraphy at many cascadia estuaries differs little from that at similar sites on passive margin coasts where stratigraphic sequences form through nonseismic processes unrelated to coseismic land level changes methods developed through study of similar stratigraphic sequences in europe provide a framework for investigating the cascadia estuarine record five kinds of criteria must be evaluated when inferring regional coastal subsidence due to great plate boundary earthquakes the suddenness and amount of submergence the lateral extent of submerged tidal wetland soils the coincidence of submergence with tsunami deposits and the degree of synchroneity of submergence events at widely spaced sites evaluation of such criteria at the cascadia subduction zone indicates regional coastal subsidence during at least two great earthquakes evidence for a coseismic origin remains equivocal however for the many peat mud contacts in cascadia stratigraphic sequences that lack 1 contrasts in lithology or fossils indicative of more than half a meter of submergence 2 well studied tsunami deposits or 3 precise ages needed for regional correlation paleoecologic studies of fossil assemblages are particularly important in estimating the size of sudden sea level changes recorded by abrupt peat mud contacts and in helping to distinguish erosional and gradually formed contacts from coseismic contacts reconstruction of a history of great earthquakes for the cascadia subduction zone will require rigorous application of the above criteria and many detailed investigations

taxonomic turnover and abundance in cretaceous to tertiary wood floras of antarctica implications for changes in forest ecology based on the temporal distribution abundance and taxonomic composition of wood floras four phases of vegetation development are recognized through the cretaceous to early tertiary of the antarctic peninsula 1 aptian to albian communities dominated by podocarpaceous araucarian and minor taxodiaceous cupressaceous conifers with rare extinct gymnosperms sahnioxylon 2 progressive replacement of these communities in cenomanian to santonian times by angiosperms most without modern analogues 3 increasing dominance of angiosperms becoming important both in terms of diversity and abundance towards the mid late cretaceous 4 modernization of the flora during the campanian to maastrichtian with the extinction of earlier forms appearance of the nothofagaceae and diversification of associated elements these patterns broadly follow trends seen in the leaf and palynological record but with some important differences during the cretaceous conifer composition undergoes a change whereby phyllocladoxylon type woods increase relative to the older podocarpoxylon forms during the paleocene to eocene period a marked extinction in wood types occurs associated with an increase in the abundance of nothofagaceous wood detailed examination of wood abundance and distributions from sections within maastrichtian and paleocene formations points to strong environmental control on taxonomic compositions similar differences are encountered when comparing coeval floras from different geographic regions and palaeoenvironments

aperiodic recurrence of geologically recorded tsunamis during the past 5500 years in eastern hokkaido japan 1 along hokkaido s pacific coast near the town of kiritappu sandy deposits in a muddy lagoon and on a nearby beach ridge plain provide evidence for 15 tsunamis between 200 and 6000 years ago additional sand beds at the lagoon probably represent the historical tsunamis of a d 1843 and 1894 we observed the sequences of sandy deposits in continuous slices 2 to 4 m deep some of the deposits consist of just a single sand bed whereas others contain multiple units of sand muddy sand or sandy mud and mud caps including plant detritus we also found at the lagoon a 17th century tsunami deposit that thickens and thins regardless of elevation or distance inland we bracketed the ages of most of the inferred tsunamis by radiocarbon dating of detritus mainly seeds and leaves at the lagoon and charcoal at the beach ridge plain from pretsunami and posttsunami beds tsunami dates computed from the bracketing ages commonly have uncertainties spanning 2 to 4 centuries within these uncertainties the inferred sequence of 15 prehistoric tsunamis at the lagoon beginning almost 6000 years ago can be matched tsunami by tsunami with the inferred history at the beach ridge plain 15 km away the sand sheet extents suggest that most of these tsunamis were larger than any generated at hokkaido in the last 200 years the intervals between these inferred outsized tsunamis average nearly 400 years but range widely from about 100 to about 800 years

the sedimentary record of the 1960 tsunami in two coastal lakes on isla de chiloe south central chile abstract this study describes sediments deposited by the tsunami following the 1960 great chilean earthquake mw 9 5 in two coastal lakes lakes cucao and huelde on the west coast of isla de chiloe south central chile 42 6 s sub bottom profiles and side scan sonar mosaics illustrate the sedimentary context of transects of gravity cores the stratigraphy of both lakes features gyttja sedimentation interrupted by the abrupt emplacement of a sandy layer with mud rip up clasts and a mud cap this sandy layer reflects a sudden change in sedimentary environment most probably caused by a high energy inundation radionuclide analyses 137cs and 210pb date the inundation deposit to shortly before the mid 1960s the only known event that matches the sedimentological and chronological criteria is the ad 1960 tsunami using grain size analysis and comparisons with samples from modern environments we demonstrate that the proximal seaward part of the deposit consists of a mixture of sand derived from subaerial sources and reworked gyttja lake sediment in the distal landward part of lake cucao the sand component is lost and the deposit consists entirely of remobilised lake sediments the repetition of tsunami deposit sequences in lake huelde suggests a minimum of three inundating waves sub bottom profiles and side scan sonar mosaics reveal tsunami inundation over the barrier and more prominently through the outlet river channel the dominant role of the river channel as a pathway for sediment transport is also described in core samples by tsunami deposits that fine away from the channel mouth the identification and description of the deposit left by a known tsunami provide important insights into tsunami sedimentation in coastal lakes and have the potential to help in the search for paleotsunami evidence

varves in lake sediments a review abstract downcore counting of laminations in varved sediments offers a direct and incremental dating technique for high resolution climatic and environmental archives with at least annual and sometimes even seasonal resolution the pioneering definition of varves by de geer 1912 had been restricted to rhythmically deposited proglacial clays one century later the meaning of varve has been expanded to include all annually deposited laminae in terrestrial and marine settings under favourable basin configurations and environmental conditions limnic varves are formed due to seasonality of depositional processes from the lake s water column and or transport from the catchment area subsequent to deposition of topmost laminae the physical preservation of the accumulating varved sequence requires the sustained absence of sediment mixing for example via wave action or macrobenthic bioturbation individual sub laminae in varved lake sediments typically express contrasting colours always differ in terms of their organic chemical and or mineralogical compositions and often also differ with regard to grain size various predominating climatic and depositional conditions may result in clastic biogenic or endogenic incl evaporitic varved sediments and their mixtures to reliably establish a varve chronology the annual character of laminations needs to be determined and verified in a multidisciplinary fashion sources and influences of possible errors in varve chronologies are best determined and constrained by repeated varve counts and by including radioisotopes and correlation with historically documented events a well established varve chronology greatly enhances the scientific value of laminated limnic archives by securely anchoring the wealth of multi proxy palaeoenvironmental information in the form of time series for multidisciplinary investigations applications of varved records are discussed with special reference to advances since the 1980s these span fields like calibrating radiometric dating methods reconstructing past changes of the earth s magnetic field or detecting fluctuations in solar forcing once a varve chronology is established it can be applied to precisely date events like volcanic ash layers earthquakes or human impact as well as short and long term climate temperature precipitation wind hydroclimatic conditions or flooding and environmental changes eutrophication pollution due to their exceptional high temporal resolution and in combination with their robust and accurate internal time scale in calendar years annually laminated sediments can be regarded as one of the most precious environmental archives on the continents these records are necessary to extend temporally limited instrumental records back in time as such they have societal relevance with regard to risk assessments related to natural hazards arising from e g flooding or volcanic eruptions

seismic inversion tracks in situ combustion a case study from balol oil field india in situ combustion is one of the approaches used for secondary recovery of heavy oil in which time lapse seismic data might be used to track the production process we have analyzed three time lapse seismic surveys carried out at a time interval of one year during pre and postcombustion phases of in situ combustion at the balol field in india interpretation of these land time lapse data using standard seismic amplitude differences in terms of reservoir changes during production and injection can be erroneous the balol data in particular lacked calibration and had poor repeatability we have addressed these issues by demonstrating the applicability of independent prestack inversion of baseline and monitor surveys to derive elastic attributes that help to produce clearer images of fluid movement independent estimates of wavelets from the baseline and two monitor surveys were used in prestack inversion to estimate acoustic impedance shear impedance and poisson s ratio the results show unexpected movement of the thermal front away from the injection wells toward the north and northwest of the injection wells farther from the production wells these results have been confirmed by well production data from the field north and northwest of balol

survey of 2011 tohoku earthquake tsunami inundation and run up 1 at 14 46 local time on march 11 2011 a magnitude 9 0 earthquake occurred off the coast of northeast japan this earthquake generated a tsunami that struck japan as well as various locations around the pacific ocean with the participation of researchers from throughout japan joint research groups conducted a tsunami survey along a 2000 km stretch of the japanese coast more than 5300 locations have been surveyed to date generating the largest tsunami survey dataset in the world on the sendai plain the maximum inundation height was 19 5 m and the tsunami bore propagated more than 5 km inland along the ria coast from about 50 to 200 km north of sendai the narrow bays focused the tsunami waves generating the largest inundation heights and run ups the survey data clearly show a regional dependence of tsunami characteristics

time lapse pre stack seismic data registration and inversion for co2 sequestration study at cranfield pre stack seismic data are indicative of subsurface elastic properties within the amplitude versus offset characteristic and can be used to detect elastic rock property changes caused by co2 injection we perform time lapse pre stack 3 d seismic data analysis for monitoring co2 sequestration at cranfield the time lapse amplitude differences of cranfield datasets are found entangled with time shifts to disentangle these two characters we apply a local correlation based warping method to register the time lapse pre stack datasets which can effectively separate the time shift from the time lapse seismic amplitude difference without changing the original amplitudes we demonstrate the effectiveness of our registration method by evaluating the inverted elastic properties these inverted time lapse elastic properties can be reliably used for monitoring co2 plumes

tohoku earthquake a surprise abstract we consider three questions related to the 2011 tohoku mega earthquake 1 why was the event size so grossly underestimated by japan s national hazard map 2 how should we evaluate the chances of giant earthquakes in subduction zones 3 what is the repeat time for magnitude 9 earthquakes off the tohoku coast the maximum earthquake size is often guessed from the available history of earthquakes a method known for its significant downward bias we show that historical magnitudes systematically underestimate this maximum size of future events but the discrepancy shrinks with time there are two quantitative methods for estimating the corner magnitude in any region a statistical analysis of the available earthquake record and the moment conservation principle however for individual zones the statistical method is usually ineffective in estimating the maximum magnitude only the lower limit can be evaluated the moment conservation technique which we prefer matches the tectonic deformation rate to that predicted by earthquakes with a truncated or tapered magnitude frequency distribution for subduction zones the seismic or historical record is insufficient to constrain either the maximum or corner magnitude however the moment conservation principle yields consistent estimates for all the subduction zones the corner magnitude is of the order 9 0 9 7 moreover moment conservation indicates that variations in estimated corner magnitude among subduction zones are not statistically significant another moment conservation method applied at a point on a major fault or plate boundary also suggests that magnitude 9 events are required to explain observed displacement rates at least for the tohoku area the global rate of magnitude 9 earthquakes in subduction zones predicted from statistical analysis of seismicity as well as from moment conservation is about five per century five actually happened

lacustrine turbidites as a tool for quantitative earthquake reconstruction new evidence for a variable rupture mode in south central chile understanding the long term earthquake recurrence pattern at subduction zones requires continuous paleoseismic records with excellent temporal and spatial resolution and stable threshold conditions south central chilean lakes are typically characterized by laminated sediments providing a quasi annual resolution our sedimentary data show that lacustrine turbidite sequences accurately reflect the historical record of large interplate earthquakes among others the 2010 and 1960 events furthermore we found that a turbidite s spatial extent and thickness are a function of the local seismic intensity and can be used for reconstructing paleo intensities consequently our multilake turbidite record aids in pinpointing magnitudes rupture locations and extent of past subduction earthquakes in south central chile comparison of the lacustrine turbidite records with historical reports a paleotsunami subsidence record and a marine megaturbidite record demonstrates that the valdivia segment is characterized by a variable rupture mode over the last 900 years including i full ruptures mw 9 5 1960 1575 1319 9 1127 44 ii ruptures covering half of the valdivia segment mw 9 1837 and iii partial ruptures of much smaller coseismic slip and extent mw 7 5 8 1737 1466 4 also distant or smaller local earthquakes can leave a specific sedimentary imprint which may resolve subtle differences in seismic intensity values for instance the 2010 event at the maule segment produced higher seismic intensities toward southeastern localities compared to previous megathrust ruptures of similar size and extent near concepci n

reconstructing paleoseismic deformation 2 1000 years of great earthquakes at chucalen south central chile in this paper we adopt a quantitative biostratigraphic approach to establish a 1000 year long coastal record of megathrust earthquake and tsunami occurrence in south central chile our investigations focus on a site in the centre of the rupture segment of the largest instrumentally recorded earthquake the ad 1960 magnitude 9 5 chile earthquake at chucalen coseismic subsidence in 1960 is recorded in the lithostratigraphy and biostratigraphy of coastal marshes with peat overlain by minerogenic sediment and changes in the assemblages of diatoms unicellular algae indicating an abrupt increase in relative sea level in addition to the 1960 earthquake the stratigraphy at chucalen records three earlier earthquakes the historically documented earthquake of 1575 and two prehistoric earthquakes radiocarbon dated to ad 1270 1450 and 1070 1220 laterally extensive sand sheets containing marine or brackish diatom assemblages suggest tsunami deposition associated with at least two of the three pre 1960 earthquakes the record presented here suggests a longer earthquake recurrence interval averaging 270 years than the historical recurrence interval which averages 128 years the lack of geologic evidence at chucalen of two historically documented earthquakes in 1737 and 1837 supports the previously suggested hypothesis of variability in historical earthquake characteristics our estimates of coseismic land level change for the four earthquakes range from meter scale subsidence to no subsidence or slight uplift suggesting earthquakes completing each 270 year cycle may not share a common characteristic slip distribution the presence of buried soils at elevations below their modern equivalents implies net relative sea level rise over the course of the chucalen paleoseismic record in contrast to relative sea level fall over preceding millennia inferred from sites on the mainland sea level rise may contribute to the preservation of evidence for multiple earthquakes during the last millennium while net relative sea level fall over the last 2000 5000 years may explain the lack of evidence for older earthquakes

effects of rainy season on mobilization of contaminants from tsunami deposits left in a coastal zone of thailand by the 26 december 2004 tsunami study on contamination of tsunami sediments deposited on 26 december 2004 conducted shortly after the tsunami in coastal zone of thailand revealed elevated contents of salts in water soluble and some heavy metals and arsenic in bioavailable fractions szczucinski et al in env geol 49 321 331 2005 few months later rainy season started and effected in total rainfall of over 3 300 mm this paper presents results of survey repeated 1 year after the tsunami to assess the effects of rainy season on mobilization of previously determined potential contaminants the same locations were sampled again and analysed with the same methods the tsunami deposit layer was well preserved but in many locations the sediments were coarser than just after tsunami due to washing out of finer fractions the water soluble salts contents were strongly reduced after the rainy season however the concentrations of acid leachable heavy metals and metalloids were still elevated in comparison to reference sample from an area not impacted by tsunami it is possible that the metals and metalloids are successively moved to more bioavailable fraction from forms which were more resistant to mobilization

going quantitative with 4d seismic analysis it is demonstrated that time lapse seismic signatures can be directly calibrated with historical data from producing and injecting wells via a reservoir simulator material balance calculation or simply using the hard data when this procedure is applied to a field over which two or more repeat surveys have been shot at different calendar times the correlation coefficients that link the seismic difference signatures to the reservoir s pressure and saturation variations are determined by utilizing several seismic attributes that respond differently to reservoir perturbations pressure and saturation changes are then independently estimated the approach is tested on synthetic data and then on data from the schiehallion field on the uk continental shelf with favourable results

4d seismic for oil rim monitoring in the central north sea gannet a field a 50 ft oil rim is overlain by a gas cap of variable thickness oil is produced from horizontal wells which initially produced dry oil but as the field became more mature a significant water cut was seen in several wells a dedicated 4d seismic monitor survey was acquired in order to assess the remaining distribution of oil reserves by forward modelling the synthetic seismic response to parameters such as contact movement and residual saturations using 2d and 3d wedge models and comparing the results with real seismic data we are able to decipher the contact movements across the field it is shown that in one part of the field the increased water cut is caused primarily by the vertical displacement of the entire oil rim into the initial gas cap this oil rim displacement produces a very different 4d seismic response from the case of a static gas oil contact and rising oil water contact normal production as a result of these observations we are able to optimize field production by both re perforation of existing wells and by drilling sidetracks into the displaced rim a brown field development opportunity that might otherwise be missed

sedimentologic and geomorphologic tsunami imprints worldwide a review abstract tsunami events with extreme effects on sedimentary transport or considerable alterations of the coastal configuration are rather rare regarding human history but considering geological timescales they occur frequently at least 100 megatsunami in different parts of the world have been recorded in the past 2000 years but presumably far more have failed to be noticed during historical times and are not mentioned either in written or oral ancient records therefore the topic of paleotsunami requires inevitable sedimentological and geomorphological research however field research concerning paleotsunami is astonishingly rare within the scientific approach and only 5 of the existing tsunami literature is related to this subject future efforts in paleotsunami research should focus on the geological evidence of these mega events to clarify their contribution to coastal forming processes this paper reviews the state of the art knowledge of sedimentologic and geomorphic imprints of tsunami along the world s coastlines in order to highlight the need for more detailed studies of paleotsunami depositional and geomorphological traces

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

a prestack basis pursuit seismic inversion abstractresolving thin layers and clearly delineating layer boundaries in inverted seismic sections are very important goals for exploration and production many seismic inversion methods based on a least squares optimization approach with tikhonov type regularization can lead to unfocused transitions between adjacent layers a basis pursuit inversion bpi algorithm based on the l1 norm optimization method can however resolve sharp boundaries between layers we have formulated a bpi algorithm for amplitude versus angle inversion and investigated its potential to improve contrasts between layers like the bpi for poststack case the sparse layer constraint rather than the sparse spike constraint is used to construct the model space as a wedge dictionary all the elements of the dictionary are bed reflectivities which include solutions consisting of thin beds as well with this dictionary we use an l1 norm optimization framework to derive three reflectivities namely rp rs and r although bpi doe

towards quantitative evaluation of gas injection using time lapse seismic data of particular concern in the monitoring of gas injection for the purposes of storage disposal or improved oil recovery is the exact spatial distribution of the gas volumes in the subsurface in principle this requirement is addressed by the use of 4d seismic data although it is recognized that the seismic response still largely provides a qualitative estimate of moved subsurface fluids exact quantitative evaluation of fluid distributions and associated saturations remains a challenge to be solved here an attempt has been made to produce mapped quantitative estimates of the gas volume injected into a clastic reservoir despite good results using three accurately repeated seismic surveys time delay and amplitude attributes reveal fine scale differences though large scale agreement in the estimated fluid movement these differences indicate disparities in the nature of the two attributes themselves which can be explained by several possible causes of most impact are the effects of processing and migration wave interference effects and noise from non repeatability of the seismic surveys this subject highlights the need for a more careful consideration in 4d acquisition amplitude processing and use of true amplitude preserving attributes in quantitative interpretation

time lapse seismic analysis of pressure depletion in the southern gas basin in the southern gas basin sgb of the north sea there are many mature gas fields where time lapse monitoring could be very beneficial in extending production life however the conditions are not immediately attractive for time lapse seismic assessment this is primarily because the main production effect to be assessed is a pore pressure reduction and frame stiffening because of gas production in tight sandstone reservoirs that also have no real seismic direct hydrocarbon indicators modelling based on laboratory measurements has shown that such an effect would be small and difficult to detect in seismic data this paper makes two main contributions firstly this is to our knowledge the first time lapse study in the sgb and involves a real data assessment of the viability for detecting production in such an environment secondly the feasibility of using markedly different legacies of data in such a study is addressed including an assessment of the factors influencing the crossmatching from the latter it is found that significant spatially varying time shifts need to be and are successfully resolved through 3 d warping after the warping the primary factors limiting the crossmatching appear to be residual local phase variations possibly induced by the differing migration strategies structure reverberations and different coherencies of the volumes caused by differences in acquisition structure azimuth and acquisition fold despite these differences a time lapse amplitude signature is observed that is attributable to production the character of the 4 d amplitude anomalies may also indicate variations in stress sensitivity e g because of zones of fracturing additionally warping derived time attributes have been highlighted as a potential additional avenue for detection of pressure depletion in such reservoirs although the effects are subtle they may indicate changes in stress pressure in and around the reservoir because of production however to fully resolve the subtle time lapse effects in such a reservoir the data differences need to be better addressed which may be possible by full re processing and pre stack analysis but more likely dedicated 4 d acquisition would be required

estimation of thickness and velocity changes of injected carbon dioxide layers from prestack time lapse seismic data in this study we bring together the two main categories of time lapse seismic analysis amplitude analysis and time shift analysis to estimate simultaneously the changes in thickness and velocity of a 4d seismic anomaly the methodology is applied to time lapse seismic monitoring of carbon dioxide c o2 storage at sleipner field norway that shows significant 4d effects the 4d anomalies resulting from c o2 injection appear as a multilayer reflection pattern within the relatively shallow utsira sand this multireflective appearance within the sand layer is interpreted as c o2 layers trapped below thin shale layers because most of the c o2 layers are believed to be thin 0 20 m the interference between top and base of these layers needs to be taken into account in 4d seismic analysis by studying the reflected event from a horizon below the utsira sand we estimate 4d traveltime shifts caused by the presence of the c o2 layer above thishorizon we then combine these traveltime shifts with measur

a global palaeoclimatic reconstruction for the valanginian based on clay mineralogical and geochemical data abstract high resolution clay mineral and 18ocarb analyses have been performed on three sections of valanginian age early cretaceous from northwestern 20 30 n and southern 53 s tethyan realms the data have been integrated in a large set of published mineralogical clays and geochemical 18ocarb 18obivalve 18olenticulina 18obelemnite and tex86 data from 17 sections situated between 45 n and 53 s based on this data set we provide new insights into valanginian climate conditions from a wide range of palaeolatitudes we highlight climate trends within specific areas and identify main climate belts in the proto north atlantic realm 15 17 n large amounts of smectite together with the occurrence of palygorskite testify for a semi arid climate belt throughout the valanginian significant variations in kaolinite content in the northwestern tethyan realm 20 to 30 n suggest that this realm has been more sensitive to changes in hydrological cycling and subsequent erosion and runoff processes during the early to early late valanginian transition interval this time interval that is coincident with the pronounced positive and globally recognized carbon isotope excursion cie the weissert episode documents the wet conditions of a humid subtropical climate belt temperature ranges derived from 18o records suggest climate warming by about 3 5 0 9 c in the northern hemisphere during the weissert episode this is followed by a global cooling of about ca 1 5 0 9 c in both hemispheres during the late valanginian we postulate that these patterns were due to interplays between tectonic and orbital factors which have controlled the distribution of regional palaeoclimate belts during the valanginian the semi arid belt expressed in the proto north atlantic realm has probably been induced by its specific palaeogeographic configuration and the existence of isolated basins which were each characterized by strong and continuous thermohaline circulation an eccentricity paced monsoon like system might have played a significant role in maintaining the subtropical belt around the northwestern tethyan realm up to the mid latitudes 35 45 n superimposed on these regional processes a widespread magmatic pulse in parana etendeka volcanic activity might have stimulated greenhouse conditions impacting marine biota and favouring the development of a dense vegetation cover on the continent an increase in sedimentary burial of 13c depleted organic carbon on the continents may have contributed to the progressive global positive carbon isotope excursion in the medium term it has also probably led to a significant decrease in atmospheric co2 as testified by the global cooling recorded during the late valanginian in both hemispheres and the probable concomitant extension of polar ice caps

is a regional flood signal reproducible from lake sediments the evolution of flood activity with global warming remains uncertain to better assess flood climate relationships lake sediments are increasingly being investigated because they could provide regional flood histories long enough to cover past climate changes however site specific sedimentary processes may bias flood reconstructions the aim of this article is to investigate these effects through the reconstruction of two distinct flood records from independent neighbouring sedimentary basins of the same lake lake allos in the mediterranean french alps i e under the same climate conditions understanding of sedimentary processes is crucial in order to adapt the sampling strategy and the flood intensity proxy to each sedimentary system and thereby reconstruct a complete and reliable flood history thanks to this detailed approach the main trends of the regional flood variability can be reproduced i e periods of high flood frequency ranges of flood frequency values and timing of the most intense events in detail some differences appeared associated to the various stream capacities to erode and transport flood sediments to the lake system implying variable sensitivity of sedimentary systems in recording floods comparing regional flood records based on independent sedimentary systems from similar environments could thus be a complementary approach to assessing past flood intensity such an approach could open particularly interesting perspectives because reconstructing the long term evolution of flood intensity is a key challenge in the geosciences

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research