history and isostatic effects of the last ice sheet in southern british columbia abstract the late wisconsinan cordilleran ice sheet covered british columbia southern yukon territory and parts of alaska washington idaho and montana its major source areas were the high mountain ranges of the canadian cordillera and flow was strongly controlled by topography the last ice sheet began to develop about 30 000 25 000 14c yr ago but it did not achieve its maximum extent until 15 000 14 000 14c yr bp ice sheet growth was interrupted locally by stillstands and retreat ice sheet decay was rapid and was characterized by complex frontal retreat at the periphery accompanied locally by brief readvances and by downwasting and stagnation by 10 000 14c yr bp

global variations of thermospheric winds and temperatures caused by substorm energy injection two numerical simulations of the thermospheric response to magnetospheric energy injection have been performed using a zonally averaged time dependent model of neutral composition dynamics and energy budget the simulations are distinguished by the duration of the source the first simulation has an energy injection of 1 hour representative of substorm type forcing and the second one has a 12 hour energy injection representative of main storm type forcing they were performed under the condition of equinox at solar minimum in the first simulation large scale atmospheric gravity waves agws generated by the substorm energy via joule heating of ionospheric currents are clearly identified in the wind field in a meridional plane as well as in the temporal and spacial variations of the total energy density of air above about 130 km height these waves reach the equator after about 3 hours and propagate into the opposite hemisphere the horizontal propagation speed is close to the speed of sound for example roughly 440 m s at about 150 km altitude and 670 m s at about 260 km altitude snapshots of the wind system affected by the substorm energy injection show a four cell pattern between the poles above 260 km the cells have the opposite rotational direction to those below these small scale features in the wind system are indicative of the internal atmospheric gravity waves with the vertical phase propagation from a term analysis of the energy conservation equation it is identified that the dominant energy process associated with the propagation of agws is adiabatic compressional heating and or expansive cooling process it can be concluded that the energy oscillations at middle and low latitude are mainly produced by agws propagating from high latitude during the substorm the second simulation indicated that horizontal and vertical advections vertical heat conduction and infrared radiative cooling by nitric oxide are important in addition to adiabatic compressional heating and or expansive cooling it is suggested that short duration energy injection preferentially generates agws which dominate the energy oscillations at low latitudes through adiabatic heating and cooling long duration energy injection is more effective in generating a meridional circulation which transfers energy by both advective and adiabatic processes

thermospheric wind during a storm time large scale traveling ionospheric disturbance 1 a prominent large scale traveling ionospheric disturbance lstid was observed in japan during the major magnetic storm dst 358 nt of 31 march 2001 it was detected as enhancements of the 630 nm airglow and fof2 gps tec variations and a decrease in f layer virtual height at 1700 1900 ut 0200 0400 lt it moved equatorward with a speed of 600 m s the decrease in the f layer height was also detected by the mu radar at shigaraki thermospheric wind variations were observed by the mu radar through ion drift measurement and by a fabry perot interferometer fpi through a doppler shift of the 630 nm airglow line at shigaraki the wind data show a turn of the meridional wind from 94 m s equatorward to 44 m s poleward during the lstid indicating that an intense poleward wind in the thermosphere passed over shigaraki as an atmospheric gravity wave and caused the observed ionospheric features of the lstid intense poleward wind was also detected at mesospheric altitudes 95 100 km by the mu radar through meteor echoes and by the fpi through the 558 nm airglow with a delay of 2 hours from the thermospheric wind indicating downward phase progression of the wave generation of the observed poleward wind in the auroral zone was investigated using magnetic field data and auroral energy input estimated by the assimilative mapping of ionospheric electrodynamics amie technique we suggest that simple atmospheric heating and or the lorentz force in the auroral zone do not explain the observed poleward wind enhancement

morphology of large scale traveling atmospheric disturbances in the polar thermosphere using a fully coupled thermosphere ionosphere plasmasphere model we investigate the morphology of modelled large scale traveling atmospheric disturbances ls tads hereinafter tads propagating both poleward and equatorward from auroral sources we confirm observational evidence of daytime ion drag reducing equatorward far field tad activity we further suggest an additional source dependent mechanism that associates tads propagating preferentially poleward with an auroral electric field burst that contains an eastward rather than a westward component these poleward tads are superimposed on the high speed neutral air winds in the polar cap originating from the day night plasma convection and exhibit speed and spatial resonance effects with the neutral wind the direction of propagation is affected by coriolis forcing due to the earth s rotation

identification of high latitude acoustic gravity wave sources using the goose bay hf radar observations of medium scale acoustic gravity waves using the goose bay hf radar are presented data were examined for the period of november and december 1991 and days that showed evidence of traveling ionospheric disturbances tids were selected for analysis tids were identified in the hf radar data by quasi periodic enhancements of the power in the ground scattered portion of the radar signal various parameters were determined from the data including the wave frequency the wavelength the propagation direction and the phase velocity it was found that multiple wave packets from multiple directions are often present simultaneously source times and locations were identified from data from 2 days december 5 and 6 1991 and these were compared with data from the greenland magnetometer chain the source times and locations were found to correspond to sudden magnetometer deflections indicating the correlation of gravity wave sources with the occurrence of ionospheric electrojet current surges finally the source times and locations were examined in local time and magnetic latitude and it was found that the sources were clustered in two locations near the magnetospheric cusp and near 1600 mlt at about 75 magnetic latitude

late quaternary slip rates across the central tien shan kyrgyzstan central asia 1 slip rates across active faults and folds show that late quaternary faulting is distributed across the central tien shan not concentrated at its margins nearly every intermontane basin contains neogene and quaternary syntectonic strata deformed by holocene north south shortening on thrust or reverse faults in a region that spans two thirds of the north south width of the central tien shan slip rates on eight faults in five basins range from 0 1 to 3 mm yr fault slip rates are derived from faulted and folded river terraces and from trenches radiocarbon optically stimulated luminescence and thermoluminescence ages limit ages of terraces and aid in their regional correlation monte carlo simulations that sample from normally distributed and discrete probability distributions for each variable in the slip rate calculations generate most likely slip rate values and 95 confidence limits faults in basins appear to merge at relatively shallow depths with crustal scale ramps that underlie mountain ranges composed of pre cenozoic rocks the sum and overall pattern of late quaternary rates of shortening are similar to current rates of north south shortening measured using global positioning system geodesy this similarity suggests that deformation is concentrated along major fault zones near range basin margins such faults separated by rigid blocks accommodate most of the shortening in the upper crust index terms 8107 tectonophysics continental neotectonics 9320 information related to geographic region asia 8010 structural geology fractures and faults

mapping crustal stress and strain in southwest british columbia 1 this paper investigates the orientation and sources of stress in the forearc of the cascadia subduction zone in southwest british columbia using bayesian inversion results from focal mechanism data and comparing results with gps derived short term strain rates the subduction margin in this region includes a change in orientation from n s in washington state to nw se in british columbia over 1000 focal mechanisms from north american crustal earthquakes have been calculated to identify the dominant style of faulting and 600 were inverted to estimate the principal stress orientations and the stress ratio our results indicate the maximum horizontal compressive stress orientation changes with distance to the trench from approximately margin normal along the coast to approximately margin parallel 100 150 km inland from the coast comparing stress orientations with gps data we relate the margin normal stress direction to subduction related strain rates due to the locked interface between the north american and juan de fuca plates just west of vancouver island further from the margin the plates are coupled less strongly and the margin parallel maximum horizontal compressive stress in the north american plate relates to the northward push of the oregon block which is also observed in the horizontal shortening direction of the residual strain rates after the subduction component is removed

holocene surface rupture history of an active forearc fault redefines seismic hazard in southwestern british columbia canada author s morell kd regalla c amos c bennett s leonard l graham a reedy t levson v telka a

two regions of seafloor deformation generated the tsunami for the 13 november 2016 kaikoura new zealand earthquake the 13 november 2016 kaikoura new zealand m w 7 8 earthquake ruptured multiple crustal faults in the transpressional marlborough and north canterbury tectonic domains of northeastern south island the hikurangi trench and underthrust pacific slab terminate in the region south of kaikoura as the subdution zone transitions to the alpine fault strike slip regime it is difficult to establish whether any coseismic slip occurred on the megathrust from on land observations the rupture generated a tsunami well recorded at tide gauges along the eastern coasts and in chatham islands including a 4 m crest to trough signal at kaikoura where coastal uplift was about 1 m and at multiple gauges in wellington harbor iterative modeling of teleseismic body waves and the regional water level recordings establishes that two regions of seafloor motion produced the tsunami including an m w 7 6 rupture on the megathrust below kaikoura and comparable size transpressional crustal faulting extending offshore near cook strait

anisotropy of experimentally compressed kaolinite illite quartz mixtures the anisotropy of physical properties is a well known characteristic of many clay bearing rocks this anisotropy has important implications for elastic properties of rocks and must be considered in seismic modeling preferred orientation of clay minerals is an important factor causing anisotropy in clay bearing rocks such as shales and mudstones that are the main cap rocksofoilreservoirs thepreferredorientationofclaysdepends mostly on the amount of clays and the degree of compaction to studytheeffectoftheseparameters wepreparedseveralsamples compressingattwoeffectiveverticalstressesamixtureofclays illite and kaolinite and quartz silt with different clay quartz ratios the preferred orientation of the phases was quantified with rietveld analysis on synchrotron hard x ray images pole figures for kaolinite and illite display a preferred orientation of clay platelets perpendicular to the compaction direction increasing in strength with clay content and compaction pressure quartz particles have a random orientation distribution aggregate elastic properties can be estimated by averaging the singlecrystal properties over the orientation distribution obtained from the diffraction data analysis calculated p wave velocity anisotropy ranges from 0 pure quartz sample to 44 pure clay sample highly compacted but calculated velocities are much higher than measured velocities this is attributed to uncertainties about single crystal elastic properties and oriented micropores and limited grain contacts that are not accounted for in themodel inthiswork wepresentaneffectivemethodtoobtain quantitative data helping to evaluate the role of clay percentage and compaction pressure on the anisotropy of elastic properties ofclay bearingrocks

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

experimental mechanical compaction of reconstituted shale and mudstone aggregates investigation of petrophysical and acoustic properties of sw barents sea cap rock sequences abstract this study investigates petrophysical and acoustic properties of experimentally compacted reconstituted samples of seal sequences from the southwestern barents sea the aggregates were collected from drill cuttings of mudstone and shale formations of two exploration wells 7220 10 1 salina discovery and 7122 7 3 goliat field the washed and freeze dried samples were characterized for grain size distributions geochemical analyses and mineralogical compositions a total of 25 compaction tests 12 dry and 13 brine saturated were performed with a maximum effective vertical stress of 50 mpa the laboratory measurements demonstrated that petrophysical and acoustic properties of argillaceous sediments can change within a sedimentary basin and even within a given formation the results show that the collected aggregates from goliat field are compacted more compared to salina discovery the maximum and minimum compaction are measured in samples collected from snadd and fuglen formations respectively the final porosity of brine saturated specimens varies between 5 and 22 the ultrasonic velocity measurements depict that samples with the same porosity values can have a broad range of velocity values the resulting compaction trends in this study were compared to published compaction curves for synthetic mixtures of quartz and clay all compaction trends show higher porosity reduction than the silt fraction with 100 quartz comparison of experimental compaction result of each mudstone and shale aggregate with its corresponding acquired well log data helps to delineate the burial history and exhumation in the study area a net exhumation of 950 m and 800 m is estimated at salina and goliat wells respectively the outcomes of this study can provide insights for hydrocarbon prospect discovery in a pre mature sedimentary basin in terms of exploration and production and also for geological co2 storage sites the experimental results may provide information for well log and seismic interpretation basin modeling and seal integrity of investigated horizons

earthquake rupture through a step over fault system an exploratory numerical study of the leech river fault southern vancouver island the leech river fault lrf zone located on southern vancouver island is a major regional seismic source we investigate potential interactions between earthquake ruptures on the lrf and the neighb

differential loading by prograding sedimentary wedges on continental margins an arch forming mechanism 1 rapid deposition of prograding sedimentary wedges on continental margins will cause excess pore pressure fluid flow and compaction as they load the substratum they may also cause faulting and structural deformation in the sedimentary succession below and in front of the load large depositional units are in addition associated with pronounced isostatic subsidence the magnitude and effects each component has on the basin as a whole is often debated to address this problem we use a quantitative approach with a coupled hydromechanical mathematical model based on linear isotropic elasticity the equations are solved by the finite element method fem in the modeling a wedge shaped load emplaced successively over a period of 1 5 myr is used to simulate the progradation of a thick sedimentary wedge results show that the differential load generates excess pressure below the prograding depocenter with lateral fluid flow in front and a tail of draining pore pressure behind the sediments are pushed downward and laterally in front of the wedge and vertical and horizontal compressional and shear stresses are generated below the wedge the formation of the helland hansen arch located in the voring basin off mid norway is genetically associated with differential loading our results indicate that the whole eastern flank of the arch is a result of differential loading whereas the western flank is mainly related to thermal subsidence since paleogene times thus alternative explanations like intraplate stress seem to be irrelevant as a genetic mechanism

recent state of stress change in the walker lane zone western basin and range province united states the nw to north trending walker lane zone wlz is located along the western boundary of the northern basin and range province with the sierra nevada this zone is distinguished from the surrounding basin and range province on the basis of irregular topography and evidence for both normal and strike slip holocene faulting inversion of slip vectors from active faults historic fault offsets and earthquake focal mechanisms indicate two distinct quaternary stress regimes within the wlz both of which are characterized by a consistent wnw 3 axis these are a normal faulting regime with a mean 3 axis of n85 9 w and a mean stress ratio r value r 2 1 3 1 of 0 63 0 74 and a younger strike slip faulting regime with a similar mean 3 axis n65 70 w and r values ranging between 0 1 and 0 2 this younger regime is compatible with historic fault offsets and earthquake focal mechanisms both the extensional and strike slip stress regimes reactivated inherited mesozoic and cenozoic structures and also produced new faults the present day strike slip stress regime has produced strike slip normal oblique slip and normal dip slip historic faulting previous workers have explained the complex interaction of active strike slip oblique and normal faulting in the wlz as a simple consequence of a single stress state with a consistent wnw 3 axis and transitional between strike slip and normal faulting maximum horizontal stress approximately equal to vertical stress or r 0 in both regimes with minor local fluctuations the slip data reported here support previous results from owens valley that suggest deformation within temporally distinct normal and strike slip faulting stress regimes with a roughly constant wnw trending 3 axis zoback 1989 a recent change from a normal faulting to a strike slip faulting stress regime is indicated by the crosscutting striae on faults in basalts 300 000 years old and is consistent with the dominantly strike slip earthquake focal mechanisms and the youngest striae observed on faults in plio quaternary deposits geologic control on the timing of the change is poor it is impossible to determine if there has been a single recent absolute change or if there is rather an alternating or cyclical variation in stress magnitudes our slip data in particular the cross cutting normal and strike slip striae on the same fault plane are inconsistent with postulated simple strain partitioning of deformation within a single regional stress field suggested for the wlz by wesnousky and jones 1994 the location of the wlz between the deep seated regional extension of the basin and range and the right lateral strike slip regional tectonics of the san andreas fault zone is probably responsible for the complex interaction of tectonic regimes in this transition zone in early to mid tertiary time the wlz appears to have had a similarly complex deformational history in this case as a back arc or intra arc region accommodating at least part of the right lateral component of oblique convergence as well as a component of extension

on the dynamics of large scale traveling ionospheric disturbances over europe on 20 november 2003 ionospheric disturbances often associated with geomagnetic storms may cause threats to radio systems used for communication and navigation one example is the super storm on 20th november 2003 when plenty of strong and unusual perturbations were reported this paper reveals additional information on the dynamics in the high latitude ionosphere over europe during this storm here analyses of wavelike travelling ionospheric distrubances tids over europe are presented based on estimates of the total electron content tec derived from ground based global navigation satellite system gnss measurements these tids are ionospheric signatures of thermospheric surges initiated by space weather events the source region of these tids is characterized by enhanced spatial gradients tec depression strong uplift of the f2 layer the vicinity of the eastward auroral electrojet and strong aurora e layers joule heating is identified as the most probable driver for the tids observed over europe during 20th november 2003 the sudden heating of the thermosphere leads to strong changes in the pressure and thermospheric wind circulation system which in turn generates thermospheric wind surges observed as tid signatures in the tec either the dissipation of the eastward auroral electrojet or particle precipitation are considered as the source mechanism for the joule heating in the course of the storm the tec observations show a southward shift of the source region of the tids these meridional dislocation effects are obviously related to a strong compression of the plasmasphere the presented results demonstrate the complex interaction processes in the thermosphere ionosphere magnetosphere system during this extreme storm

predictive modelling of structure evolution in sandbox experiments in this paper a computational approach is presented that is able to forward model complex structural evolution with multiple intersecting faults that exhibit large relative movement the approach adopts the lagrangian method complemented by robust and efficient automated adaptive meshing techniques a constitutive model based on critical state concepts and global energy dissipation regularized by inclusion of fracture energy in the equations governing state variable evolution the efficacy of the approach is benchmarked by forward simulation of two extensional analogue experiments that exhibit the development of a roll over anticline with a series of superimposed crestal collapse graben systems these sandbox experiments are excellent benchmarks for computational models as both intersecting localisations with different rates of slip and large relative movement on localisations must be represented while other complex phenomena associated with structural evolution over geological timeframes are not present

porosity reduction by pressure solution a theoretical model for quartz arenites pressure solution and the subsequent precipitation of the dissolved material may play an important role in the lithification of sandstones and limestones this paper presents a one dimensional model for a well sorted quartz arenite sequence undergoing diagenesis the sedimentary sequence is treated as a saturated porous medium in which pressure solution occurs at individual grain contacts quartz dissolved at grain contacts precipitates on free surfaces of adjacent grains this solution and precipitation process reduces porosity and forces the migration of pore fluid permeability decreases with porosity hindering fluid migration and excess fluid pressures are generated distributions of porosity pore pressure and fluid flow rates are given for several sedimentation rates and thermal gradients complete reduction of the primary intergranular porosity was accomplished in all cases examined by a depth of 3 5 km

pressure and temperature evolution in sedimentary basins summary this article is about what influence continuous sedimentation has on the excess pressure compaction and temperature in a sedimentary basin we give an answer in terms of two dimensionless numbers 4 and a1 which characterize the pressure and the temperature solution respectively 1 is shown to define a transitional zone between excess pressured basins with low compaction and hydrostatic basins with high compaction the 4 parameter generalizes earlier results of gibson the most important physical parameter in a is the ratio between the permeability and the sedimentation rate by means of we can quantify when high sedimentation rates and low permeability yield high excess pressures this analysis is based on the porosity given by formulae of the form 4 aps where ps is the effective stress and a is some scaling factor in an analogous manner ai 1 defines a transitional zone when moving boundary effects become marked on the temperature the most important parameter in ai is the ratio between a and the sedimentation rate simulation results are obtained by solving dimensionless pressure and temperature equations the numerical pressure solution is compared with the exact solution given by gibson and is shown to be in excellent accordance

simultaneous reactivation of two subparallel inland normal faults during the mw 6 6 11 april 2011 iwaki earthquake triggered by the mw 9 0 tohoku oki japan earthquake the gigantic m w 9 0 11 march 2011 tohoku oki earthquake suddenly changed the overriding inland area to an extensional stress regime and triggered massive seismic swarms in the coastal region the largest earthquake of m w 6 6 struck southern fukushima on 11 april 2011 and ruptured two previously mapped faults the northwest nw trending yunodake fault and the north northwest nnw trending itozawa fault clear 15 km long and 14 km long surface ruptures appeared along both faults respectively exhibiting a predominantly normal sense of slip down to the west the maximum vertical offset on the yunodake fault is 0 8 m whereas that on the itozawa fault is 2 1 m the itozawa fault rupture is in part marked by uphill facing scarps which is discordant with the large scale topography but consistent with saddled ridges and ponded alluvium the yunodake fault which bounds a neogene half graben structure juxtaposing mesozoic metamorphic rocks against neogene sedimentary rocks shows left lateral deflections of streams seismological data and interviews of local residents revealed that the two subparallel faults ruptured simultaneously based on the location of its hypocenter we however interpret that the itozawa rupture was primary and then triggered normal faulting on the yunodake fault under the heightened coulomb stress caused by the preceding tohoku oki earthquake our paleoseismic trench across the itozawa fault exposed evidence for a penultimate earthquake that occurred sometime between 12 620 and 17 410 cal yr b p there is no evidence that the itozawa fault ruptured during or immediately after the a d 869 jogan earthquake which is believed to be the penultimate giant megathrust earthquake along the japan trench

geomagnetic conjugate observations of large scale traveling ionospheric disturbances using gps networks in japan and australia 1 the geomagnetic conjugacy of large scale traveling ionospheric disturbances lstids was studied using total electron content tec data derived from gps networks in japan and australia the number of simultaneous occurrences of lstids within 1 hour in both hemispheres was 5 out of 20 21 events in japan australia when kp 5 and 0 out of 15 10 when kp 4 as for the lstids observed simultaneously in both hemispheres the propagation velocities of equatorward lstid were comparable between the two hemispheres with differences of 10 40 the crossing times at 30 geomagnetic latitude of the simultaneous lstids over japan and australia were also different by several tens of minutes for all five events these observational results indicate that the lstids observed almost simultaneously in both hemispheres are not connected electromagnetically through the geomagnetic field but are generated by atmospheric gravity waves propagating to the equator independently in the two hemispheres

mechanical behaviour of fine grained sediments experimental compaction and three dimensional constitutive model abstract the usual undimensional description of deformations of sediments based on a phenomenological relationship between porosity and the vertical effective stress does not give information about the horizontal stress and moreover is irrelevant for sedimentary structures in which deformation process is not only vertical modelling three dimensional deformation processes in sedimentary basins requires a three dimensional mechanical constitutive model for sediments a special dometric cell was conceived in g 3s this cell allows the measurement of the lateral stress during dometric compaction and so enables us to elaborate a three dimensional model of mechanical behaviour four varieties of fine grained sediments were studied by this cell in a large scale of strain and stresses the modified cam clay model was used for fitting the experimental data and it was shown that this model can reproduce the mechanical compaction of sediments up to 50 mpa of vertical effective stress about 3 km burial depth if its parameters are deduced from dometric zero lateral strain data

crustal extensional faulting triggered by the 2010 chilean earthquake the pichilemu seismic sequence 1 we report a sequence of crustal quakes that began after the mw 8 8 thrust subduction maule earthquake that affected the central chile margin on 27 february 2010 this activity lasted by several months having the most important events on 11 march 2010 mw 6 9 and mw 7 0 with normal focal mechanisms seismicity shows a rupture oriented along a nw striking and sw dipping normal fault from the surface down to the interplate contact seismicity can be correlated with neotectonics extensional structures similarly oriented in the region which have coexisted with nne ssw reverse faults since the late pliocene even though both have older periods of activity since the paleozoic this crustal rupture would have been triggered by the high coulomb stress change produced by the maule earthquake enhanced by likely fluid presence along weakened zones of the forearc crust as evidenced by high vp vs ratio the occurrence of relevant neotectonic activity in coincidence with short term deformation suggests a relationship with long term tectonic features of this region which would have been acting as a barrier during the interseismic period increasing the strain accumulation and triggering contractional faulting in the crust as well as producing high slip patches during great subduction ruptures favoring triggering of crustal extensional faulting crustal faulting in pichilemu suggests that this kind of events should be considered in seismic hazard analysis despite the absence of historical crustal seismic activity before the maule earthquake

the measurement of soil stiffness in the triaxial apparatus this paper describes a simple technique for accurately measuring the mean local axial strains of triaxial samples over a central gauge length the technique makes use of an axial displacement gauge which is a development of one devised by burland symes 1982 which makes use of electrolytic levels the device can resolve to less than 1 m over a range of 15 mm is simple to mount on the specimen and is not damaged when the sample is taken to failure the results of undrained triaxial tests are presented for a wide spectrum of soil types ranging from sands through intact reconstituted and remoulded low plasticity till undisturbed london clay to intact unweathered chalk the test results show that conventional external measurements of displacement contain errors which are frequently so large that their use in the determination of soil stiffness at working levels of stress is invalid the errors mainly result from tilting of the sample bedding at the end platens and the effects of compliance in the app

mechanical and chemical compaction model for sedimentary basin simulators abstract this article presents a sediment compaction model for sedimentary basin simulators the concepts previously used in sedimentary basin models are generalized and described in our model based on the formalism specific to rock and soil mechanics sediment compaction is described on a geological time scale by an elastoplastic model in which the elastic modulus and the strain hardening modulus increase when deformation increases the plastic limit is the maximum vertical effective stress reached by the sediment the rheology of the sediment is defined by a relationship that couples the porosity or volume of the sediment with the vertical effective stress assuming uniaxial deformation the model also incorporates a viscoplastic term in the compaction equation this component macroscopically considers viscous compaction phenomena such as pressure solution the viscosity coefficient is considered to be a function of the temperature some theoretical considerations allow us to conclude that the thermal dependency of the viscosity is given with an arrhenius law in which the activation energy ranges from 20 kj mole to 50 kj mole using viscosity coefficients extrapolated from previous laboratory experiments a sensitivity study shows significant effects of viscous deformation on the compaction of basins older than 1 ma in another study the viscosity coefficient is determined by matching the results of numerical simulations with laboratory and borehole data obtained from literature for chalk a constant viscosity coefficient of 2 5 gpa ma 8 1022 pa s has been determined assuming viscosity as a function of temperature with an activation energy of 40 kj mole chalk viscosity at 15 c is calibrated around 25 gpa ma simulations with different thermal gradients show that porosity is a function of the temperature furthermore simulations covering different lengths of time show that porosity is also a function of time

estimating tectonic history through basin simulation enhanced seismic inversion geoinfomatics for sedimentary basins summary a data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted the approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin tectonic history has a first order effect on the physical and chemical processes that govern the evolution of sedimentary basins we demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction transport mechanical rtm basin model we demonstrate the method by reconstructing the geothermal gradient as thermal history strongly affects the rate of rtm processes operating in a sedimentary basin variations in geothermal gradient history alter the present day fluid pressure effective stress porosity fracture statistics and hydrocarbon distribution all these properties in turn affect the mechanical wave velocity and sediment density profiles for a sedimentary basin the present day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged using texture and fluid properties predicted by our basin rtm simulator we generate synthetic seismograms linear correlation using power spectra as an error measure and an efficient quadratic optimization technique are found to be most effective in determining the optimal value of the tectonic parameters preliminary 1 d studies indicate that one can determine the geothermal gradient even in the presence of observation and numerical uncertainties the algorithm succeeds even when the synthetic data has detailed information only in a limited depth interval and has a different dominant frequency in the synthetic and observed seismograms the methodology presented here even works when the basin input data contains only 75 per cent of the stratigraphic layering information compared with the actual basin in a limited depth interval

comparing the cross polar cap potentials measured by superdarn and amie during saturation intervals 1 assimilative mapping of ionospheric electrodynamics amie and super dual auroral radar network superdarn are two commonly used techniques to measure cross polar cap potential pc in this study i compare pc inferred from amie with that inferred from superdarn during saturation intervals measurements from defense meteorological satellite program dmsp and polar cap pc index are also used to help estimate true pc seven saturation events in 2000 were selected for each event i ran the amie software driven by magnetometer data only by magnetometer data and superdarn data and by superdarn data only then i compared pc obtained from amie with that from superdarn i found that 1 pc inferred from superdarn is significantly lower than that inferred from other techniques including amie when pc is large e g greater than 150 kv 2 pc inferred from amie with superdarn input is much higher than pc inferred from superdarn 3 pc inferred from amie with magnetometer input tends to give the same results as that inferred from amie with magnetometer and superdarn input 4 pc inferred from amie with magnetometer input is in general in agreement with pcinferred from amie with superdarn input it is suggested that reason for the low values of superdarn derived pc during saturation intervals is that the superdarn algorithm to compute pc from measurements is not applicable to such intervals

assimilative mapping of ionospheric electrodynamics in the thermosphere ionosphere general circulation model comparisons with global ionospheric and thermospheric observations during the gem sundial period of march 28 29 1992 satellite and ground based observations from march 28 to 29 1992 were combined in the assimilative mapping of ionospheric electrodynamics amie procedure to derive realistic global distributions of the auroral precipitation and ionospheric convection which were used as inputs to the national center for atmospheric research ncar thermosphere ionosphere general circulation model tigcm comparisons of neutral model winds were made with fabry perot measurements and meridional winds derived from ionosondes the peak equatorward winds occurred 1 2 hours later in the model gravity waves launched from high latitude joule heating sources reached the equator in about 2 hours and agreed with observed variations in the height of the maximum electron density hmf2 and in the meridional winds joule heating events produced minima in the o n2 ratio that moved equatorward and usually westward in longitudinal strips which lasted about a day changes in the o n2 ratio and in the peak electron density nmf2 were strongly correlated so the observed daytime nmf2 values for stations near 50 magnetic latitude were generally reproduced by amie tigcm on the second day of the simulation the amie tigcm underestimated the electron density after midnight by up to a factor of 2 in midlatitudes while the modeled f2 layer was about 35 km lower than the observations at midnight shifting the model winds 2 hours earlier at night could double the nmf2 at 0400 lt and increase hmf2 by 20 km nmf2 could also be increased at night by realistically increasing the tigcm nighttime downward fluxes of o at the upper boundary

simultaneous mesosphere lower thermosphere and thermospheric f region observations during geomagnetic storms 1 simultaneous mesosphere lower thermosphere mlt and thermospheric f region observations made during geomagnetic storms are presented using the mu radar 35 n 136 e in alternate meteor and incoherent scatter is modes mf radar 45 n 136 e optical mesosphere thermosphere imagers omti 35 n 136 e and over 1000 gps receivers in japan the observations were made during one of the mtec s mesosphere thermosphere experiments for coupling studies campaigns conducted during 23 march to 2 april 2001 when a major storm with dst reaching 358 nt and a moderate storm with dst reaching 112 nt occurred and solar activity varied from high to very high f10 7 220 to 270 the campaign has provided zonal and meridional wind velocities at mlt altitudes 80 95 km over the mu and mf radars meridional wind velocity in the upper thermosphere 220 450 km and ionospheric electron density 150 600 km peak height and plasma drift velocity over the mu radar all sky airglow intensities at 557 7 nm 630 0 nm and 777 4 nm wavelengths over the mu radar location and vertical gps tec all over japan study of the data indicates that following the major storm the meridional wind in the upper thermosphere over the mu radar 35 n becomes weak less poleward during daytime and its diurnal amplitude reduces the winds and tides at mlt altitudes show changes during both nonstorm times and storm times but this study is not able to confirm any statistically significant changes related to the storms in the ionosphere following the onset of the major morning storm the electron density increases at altitudes near and above the ionospheric peak which after about 5 hours is followed by large increase in density at all altitudes above about 200 km on the following night though the density is generally low there is a large increase in density in the bottomside for about 3 hours centered at 0230 lt during this time a rare intense optical activity has occurred at all wavelengths 557 7 nm 630 nm and 777 4 nm over the low midlatitude location 35 n and an associated large scale traveling ionospheric disturbance lstid has propagated from north to south at f region altitudes

some laboratory measurements of permeability of bothkennar clay in relation to soil fabric laboratory measurements of the vertical and horizontal permeability of samples of bothkennar clay have been made in controlled flow tests and values have been estimated from interpretation of consolidation tests the permeability anisotropy that has been observed can be linked with different clay facies that have been identified in parallel engineering geological studies la mesure de la permeabilite verticale et horizontale d echantillons d argile de bothkennar a ete faite dans des essais d ecoulement d eau controles et des valeurs ont ete estimees a partir de l interpretation d essais de consolidation l aniso tropie de la permeabilite qui a ete observee peut etre reliee avec differents facies argileux qui ont ete identifies dans des etudes de geologie appliquee menees en parallele

northeastward motion of nighttime medium scale traveling ionospheric disturbances at middle latitudes observed by an airglow imager 1 nighttime medium scale traveling ionospheric disturbances mstids observed in 630 nm airglow images at middle latitudes are known to have a predominantly northwest southeast phase surface and to move southwestward in the northern hemisphere of earth however the mechanisms of mstid generation and their systematic southwestward motion have not been clarified in this paper we report the northeastward motion of the mstids observed at paratunka far east russia 52 97 n 158 25 e using an all sky 630 nm airglow imager at 2000 2300 lt on 19 august 2007 the mstids moved first southwestward but then back northeastward in the northern part of the images the northeastward motion of the mstids took place coincident with a f layer height decrease observed by an ionosonde at paratunka the f layer height decrease was also confirmed by an enhancement of the 630 nm airglow intensity which seemed to propagate from northeast to southwest this fact suggests that the f layer height decrease was caused by poleward wind enhancement rather than westward electric field these observations imply that the f layer height decrease or the poleward thermospheric wind has some role in the northeastward turning of the mstid propagation direction

slip rate variations on normal faults during glacial interglacial changes in surface loads geologic and palaeoseismological data document a marked increase in the slip rates of the wasatch fault and three adjacent normal faults in the basin and range province during the late pleistocene early holocene epochs the cause of this synchronous acceleration of fault slip and the subsequent clustering of earthquakes during the holocene has remained enigmatic although it has been suggested that the coincidence between the acceleration of slip and the shrinkage of lake bonneville after the last glacial maximum may indicate a causal relationship here we use finite element models of a discrete normal fault within a rheologically layered lithosphere to evaluate the relative importance of two competing processes that affect fault slip postglacial unloading the removal of mass which decreases the slip rate and lithospheric rebound which promotes faster slip we show that lithospheric rebound caused by regression of lake bonneville and deglaciation of adjacent mountain ranges provides a feasible mechanism for the high holocene rates of faulting in the wasatch region our analysis implies that climate controlled changes in loads applied to earth s surface may exert a fundamental control on the slip history of individual normal faults

factors controlling the thermo mechanical deformation of oil shales implications for compaction of mudstones and exploitation abstract six permian to miocene organic matter rich mudstones were subjected to unconfined compression tests under three thermo mechanical regimes the aims of this study were to assess the role of factors that control deformation and highlight implications for mudstone compaction and oil shale exploitation axial strain ranged from 1 9 to 23 at 25 c 5 3 70 mpa 12 79 at 25 310 c 31 42 mpa and 1 38 40 at 25 350 c 0 8 mpa the axial strain data showed that the principal factor controlling mudstone compaction is temperature with a secondary role for effective stress during high temperature tests dehydration of smectite in the 94 150 c interval resulted in a distinct axial strain effect decomposition of organic matter and other minerals caused visible strain only above 280 c tests up to 350 c resulted in mass loss of 4 54 43 8 wt with 1 1 8 wt due to organic matter a strong positive correlation was found between the petroleum generation indices 4 6 55 8 and expulsion efficiencies 38 6 96 2 while compaction 0 68 51 4 correlated with axial strain 1 38 40 solid volume loss 2 55 12 15 due to petroleum generation from kerogen resulted in an increase in porosity 1 56 6 36 low rate heating and low retorting temperature are necessary to optimise yield from oil shale exploitation

implications of fault slip rates and earthquake recurrence models to probabilistic seismic hazard estimates abstract increasingly fault slip rates are being used to constrain earthquake recurrence relationships for site specific probabilistic seismic hazard ground motion assessments this paper shows the sensitivity of seismic hazard assessments to variations in recurrence models and parameters that incorporate fault slip rates two models are considered to describe the partitioning of the slip rate or seismic moment rate into various magnitude earthquakes an exponential magnitude distribution and a characteristic earthquake distribution assuming an exponential distribution the activity rate n m 0 is constrained by the upper bound magnitude m u the b value for the region and the fault slip rate s for a given s variations in m u and b value have significant effects on recurrence and computed hazard depending on whether the assumption is made that the seismicity rate is constant or the moment rate is constant there is increasing evidence that the characteristic earthquake model is more appropriate for individual faults than the exponential magnitude distribution based on seismicity data from areas having repeated large earthquakes a generalized recurrence density function is developed and the resulting recurrence relationship requires only m u b value and s a comparison of the recurrence relationships from this model with the historical seismicity and paleoseismicity data on the wasatch and san andreas faults shows a good match the computed hazard based on the characteristic earthquake model differs from that obtained for the exponential model as a function of the fault to site distance and the acceleration level one check on the recurrence models using slip rate is to compare over large regions activity rates based on seismicity data and slip rate data such a comparison in the western transverse ranges shows a reasonable match for both the exponential and characteristic earthquake models in the moderate to large magnitude range

observations and simulations of quasiperiodic ionospheric oscillations and large scale traveling ionospheric disturbances during the december 2006 geomagnetic storm 1 a numerical simulation was performed to investigate quasiperiodic ionospheric oscillations that were observed with periods of 4 5 h by the ionosonde network okinawa yamagawa kokubunji and wakkanai in japan during the 15 december 2006 magnetic storm this simulation used the coupled magnetosphere ionosphere thermosphere cmit 2 0 model the cmit model reproduced the main characteristics of the observed ionospheric oscillations although it remains a challenging task to simulate the observations in a quantitative sense term analysis of the ion continuity equation demonstrated that the ionospheric oscillations in this event were mainly induced by the disturbed neutral winds which were associated with the large scale thermospheric circulation and traveling atmospheric disturbances tads during the storm the tads simulated from the model were then compared with those observed by the gps earth observation network geonet in japan to validate the simulation results a prominent northward propagating large scale traveling ionospheric disturbance lstid during daytime seen by the geonet total electron content tec data was captured by the cmit model two southward lstids observed by geonet gps network were also reproduced by the cmit model however the model gave faster phase speeds for the southward propagating lstid occurred during 0620 0800 ut and the northward propagating lstid furthermore the model missed the lstid seen in the tec perturbation data during 0140 0220 ut finally both observations and simulations showed a strong hemispheric asymmetry for the tad propagation that occurred during 0000 0400 ut which may be associated with the hemispheric asymmetry of the change of joule heating at high latitude

sedimentary basin deformation an incremental stress approach abstract a key component of sedimentary basin evolution is the spatial distribution and temporal variation of stress and deformation the many deformation processes poroelasticity fracturing irreversible nonlinear viscosity and pressure solution are inextricably bound in a tightly coupled network which in turn is coupled to a myriad of basin diagenetic thermal and hydrologic processes in the approach presented here the various deformation processes are integrated through an incremental stress approach together with mass momentum and energy conservation this approach yields a complete fully coupled basin model that captures basin and fault phenomena that are beyond the scope of simpler or decoupled models many of the most interesting basin phenomena are not only dependent on multiple coupled processes but also are fundamentally three dimensional to address this three dimensional complexity we have developed a numerical simulator using a moving adapting accreting finite element grid which is allowed to deform and to grow and adapt with the addition of sediment to capture smaller sedimentary features as a result our fully coupled comprehensive model allows one to solve a number of key problems in basin and fault dynamics these include compaction fractured reservoir and compartment genesis and dynamics examples illustrating these applications are presented for idealized systems and the piceance basin colorado and the permian basin west texas the incremental stress rheology is found to be a powerful formalism for integrating basin hydrology diagenesis and mechanics

role of effective permeability distribution in estimating overpressure using basin modelling abstract overpressure generation is a function of the rates of sedimentation compaction fluid generation from kerogen and dehydration of minerals and most importantly the lateral distribution of permeability within a basin as this controls lateral drainage sedimentary basins however are typically highly heterogeneous with respect to primary sedimentary facies diagenesis and tectonic development while fluid flow models based on idealised homogeneous basins may further our understanding of the processes that influence overpressure development the results are very sensitive to the distribution of rock properties particularly permeability the absolute permeability of sedimentary rocks varies from more than 1 darcy to less than 0 01 nanodarcy nd 10 11 darcy simple calculations assuming vertical flow and no lateral drainage within the basin show that overpressures approaching fracture pressure in the overburden will be reached if the effective permeability of the shale forming the seal is less than 0 1 0 01 nd 1 10 22 1 10 23 m 2 the permeability of shales varies greatly as a function of primary textural and minnerlogical composition and it is not possible to accurately predict the effective permeability of a sequence of shales forming pressure barriers overpressure in uplifted basins where there is no compaction taking place can only be maintained over geological time if the permeabilities are much lower overpressure is often controlled by lateral drainage but the effective permeabilities for fluid flow across faults and the offset of permeable layers are also difficult to predict in most cases uncalibrated basin modelling is unable to accurately predict the magnitude and distribution of overpressures because the vertical and horizontal permeabilities in sedimentary basins cannot be determined in sufficient detail in basins that have been extensively explored and developed incorporation of prior geological knowledge into basin models may allow overpressures to be predicted ahead of the drill bit however with such a large body of information already gathered about the basin it is debatable what extra value basin modelling is providing to pressure predictions

a large scale traveling ionospheric disturbance during the magnetic storm of 15 september 1999 enhancement of gps total electron content 1 0 10 16 m 2 multipoint and imaging observations of these parameters show that the lstid moved equatorward over japan with a velocity of 400 450 m s from a comparison with the sheffield university plasmasphere ionosphere model supim we conclude that an enhancement 250 300 m s of poleward neutral wind that is propagating equatorward caused these observational features of the lstid at midlatitudes to investigate generation of the lstid by auroral energy input we have used auroral images obtained by the polar uvi instrument magnetic field variations obtained at multipoint ground stations and the empirical joule heating rate calculated by the assimilative mapping of ionospheric electrodynamics amie technique intense auroral energy input was observed at 0800 1100 ut 4 6 hours before the lstid probably causing equatorward neutral wind at lower latitudes it is likely that the poleward wind pulse that caused the observed lstid was generated associated with the cessation of this equatorward wind the effect of lorentz force is also discussed index terms 0310 atmospheric composition and structure airglow and aurora 2427 ionosphere ionosphere atmosphere interactions 0335 2435 ionosphere ionospheric disturbances 2437 ionosphere ionospheric dynamics 2788 magnetospheric physics storms and substorms keywords large scale traveling ionospheric disturbance thermosphere ionosphere coupling magnetic storm airglow imaging gps network ionosonde

1 d modelling rock compaction in sedimentary basins using a visco elastic rheology abstract recent experimental studies on unlithified sediments suggest that the compaction is in part viscous at the basin scale and on a geological time scale processes such as pressure solution can be approached by creep deformation subjected to a viscous rheology in the present work we have studied porosity reduction and fluid pressure development resulting from the visco elastic compaction of a sedimentary basin during its formation model equations include continuity equations darcy s law and a visco elastic rheology law which relates the strain rate to the effective stress and to the rate of change of this effective stress under the assumption that permeability is a power law function of porosity the equations become essentially non linear model results illustrate how the decrease of porosity starts at the base of the basin and spreads upward with increasing time in a wide range of input parameter values calculations indicate a zone of almost linear increasing of pore pressure just below the basin surface a transition zone of rapidly increasing fluid pressure with a large pressure gradient and a zone of lithostatic fluid pressure below this is consistent with the general features of zoning of fluid pressure distribution in overpressured areas but zones with high pressure also correspond to low porosity at depth the relative thickness of the zones depends on time subsidence velocity and the physical parameters of sediments which can be combined in order to define a characteristic compaction length and a characteristic compaction time in the upper zone the decrease of porosity results in a boundary layer within this layer the porosity decreases from its initial value down to its minimum value the deeper zone appears when the time of formation of the given depth basin exceeds the characteristic compaction time and the thickness of the basin is in order of compaction length zones of fluid overpressure may also develop due to the spatial variations of the physical properties of the sediments

paleoseismic results from the alpine site wasatch fault zone timing and displacement data for six holocene earthquakes at the salt lake city provo segment boundary

probabilistic seismic hazard analysis of victoria british columbia considering an active fault zone in the nearby leech river valleyprobabilistic seismic hazard analysis of victoria british columbia

evolution of microstructures and of macroscopic properties of some clays during experimental compaction abstract in order to understand the evolution of clay sediments during their burial to three or four kilometers depth remoulded and non remoulded clay samples were oedometrically consolidated under loads ranging from 0 1 50 mpa and their microstructural mechanical and transport properties were studied for this study four clays were selected on mineralogical grounds a kaolinite st austell clay two illitic clays la bouzule clay and salins 14 clay and an illite smectite mixed clay marais poitevin clay among those materials two are almost pure clays st austell clay and salins 14 clay and were compacted in a remoulded state the other two have a clay fraction about 60 and were studied in non remoulded state for marais poitevin clay and both remoulded and non remoulded for la bouzule clay the oedometric tests have been performed in classical oedometers and in a new oedometric cell specially designed to measure lateral stresses and to perform hydraulic conductivity measurements under compaction load the two pure clays show an evolution of their void ratio differing from what is expected considering their liquid limits the behaviour seems to be governed by the size of the clay particles around 1 m for st austell clay and around 0 1 m for salins 14 clay marais poitevin clay very slightly compacted in its natural state and remoulded la bouzule clay have consolidation coefficients cc and void ratios consistent with their liquid limits a relationship reported in soil mechanics literature skempton 1944 burland 1990 nagaraj et al 1994 the natural la bouzule clay shows very low void ratios and cc due to overconsolidation the microstructure observed by tem showed that clay particles are platy and made of aggregates of individual crystals except for salins 14 clay where individual crystals do not aggregate the evolution of the microstructure with applied stress shows no change in the particles structure but a progressive reorientation of the particles perpendicular to the load axis these microstructural observations explain the transport properties measured and their evolution the thermal conductivity of kaolinite measured in the axial and radial direction reflects the evolution of anisotropy with compaction observed on particles orientation the different hydraulic conductivities observed on the various samples are compared to those obtained with the kozeny carman formula using two types of specific surface determination this comparison emphasizes the importance of inter and intraparticule pore size and of their intimate organisation

modeling of natural fracture initiation and propagation in basin sedimentation context during sedimentation buried rocks are subjected to an increase in vertical stress this increase leads to a decrease of porosity that is commonly called mechanical compaction indeed the mechanical compaction depending on its rate and on the permeability of the burden rocks can induce significant overpressures thus a competition is initiated between the dissipation of fluid overpressure and sedimentation rate and may result in fracture initiation the present study deals with the initiation and propagation of natural fracture in sealing formations a particular emphasis is put on mode i fracture propagation an analytical solution of the pressure and stresses in a sealing formation is proposed under sedimentation by superposing two problems of poroelasticity this analytical solution and a damage criterion are used to predict the initiation and propagation of the fracture the damage parameter affects both the mechanical and hydraulic openings of the fracture and the flow in the fracture is described by poseuille s law the fracture propagation and growth are studied by numerical simulations based on a finite element code dedicated to fractured porous media called porofis interactions between hydraulic and mechanical processes are also studied and a sensitivity study is carried out in order to find the most important parameters involved in natural fracturing under sedimentation

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

the devils mountain fault zone an active cascadia upper plate zone of deformation pacific northwest of north america abstract the devils mountain fault zone dmfz extends east to west from washington state to just south of victoria british columbia in the northern strait of juan de fuca of canada and the usa recently collected geophysical data were used to map this fault zone in detail which show the main fault trace and associated primary and secondary conjugate strands and extensive northeast southwest oriented folding that occurs within a 6 km wide deformation zone the fault zone has been active in the holocene as seen in the offset and disrupted upper quaternary strata seafloor displacement and deformation within sediment cores taken close to the seafloor expression of the faults data suggest that the present dmfz and the re activated leech river fault may be part of the same fault system based on the length and previously estimated slip rates of the fault zone in washington state the dmfz appears to have the potential of producing a strong earthquake perhaps as large as magnitude 7 5 or greater within 2 km of the city of victoria

elastoplastic deformation of porous media applied to the modelling of compaction at basin scale abstract for simulation and modelling of coupled phenomena occurring during basin evolution the mechanical aspects of rock deformation are generally restricted to vertical compaction characterized by a simple relation between the effective vertical stress and the rock porosity elasto plasticity leads to a more general formulation which in principle allows for the calculation of horizontal deformation and stress field various aspects of this application of continuum mechanics to the compaction of sedimentary rocks at basin scale are presented firstly the problems of mechanical deformation and of fluid flow or pressure evolution are shown to be intimately coupled through the effective stress concept the elasto plastic cam clay rheology is recalled as a satisfactory approach of the stress strain relationship for fine grained sediments this gives the complete bases for numerical modelling of the hydro mechanical problems related to sedimentary basin evolution secondly two numerical codes which are of standard use in civil engineering problems are tentatively applied to basin modelling the first code cesar is a finite element one which fully takes into account the hydro mechanical couplings the slow sedimentation process whereby the geological structure is progressively built can be accounted for by incremental deposition of layers in practice the computation is so time consuming that only restricted simulation on existing sedimentary structure can be seriously considered a second computer code flac based on finite difference method is then applied some special development makes it possible to account for the geometrical evolution build up of a basin and some cases studies are presented to show the importance of lateral deformation during the development of a margin type basin however these possibilities were obtained at the expense of a fixed fluid pressure field and we did not succeed in coupling the hydraulical and mechanical computations thirdly a simple incremental mechanical model is proposed for completely solving the coupled hydro mechanical problem in the case of progressive sedimentation a numerical solution is obtained in the 1 d case and gives results which are consistent with some published ones since it is 1 d this solution offers only a few advantageous features at present however generalization to several dimensions can be imagined

geological perspectives on consolidation of clay rich marine sediments 1 experimental consolidation of uncemented clay rich marine sediments provides information concerning their stress history a main finding is that some of the well known behavior of soft sediment deformation in geotechnical applications cannot validly be extrapolated to sediments that have been subjected to higher stresses and longer times of geologic conditions this study confirms that the yield stress of the uncemented sediment accurately reflects its previous maximum consolidation state furthermore we have identified a new phase of post yield strain that is associated with higher values of the modified compression index the slope of the porosity versus the logarithm of effective vertical stress than that of elastic deformation but with much lower values than that for primary consolidation this post yield behavior is a linear non elastic deformation and is termed tertiary consolidation yield stress appears independent of creep time or strain rate whereas the tertiary primary consolidation transition is sensitive to these parameters during post yield creep secondary consolidation the slope of the porosity versus the logarithm of time curve or the secondary consolidation index is generally assumed constant however this is not valid for claystones at effective vertical stresses above about 1 mpa where the secondary consolidation index increases with stress at a given effective vertical stress the secondary consolidation index also increases with creep times greater than about 105 s 28 h

ground observation and amie tiegcm modeling of a storm time traveling ionospheric disturbance 1 this paper reports the first comparison between comprehensive observations of equatorward moving traveling ionospheric disturbance at midlatitudes and thermospheric general circulation model with high latitude energy input based on data assimilation a prominent traveling ionospheric disturbance tid was observed during the major magnetic storm of 31 march 2001 the tid propagated from north to south over japan with phase speeds of 370 640 m s the assimilative mapping of ionospheric electrodynamics amie technique was used as input to the thermosphere ionosphere electrodynamics general circulation model tiegcm to investigate generation and propagation of the observed tid in the model two joule heating enhancements in the high latitude dayside sector produced two distinct traveling atmospheric waves tads which propagated to japan in the midnight sector as enhancements in thermospheric temperature and southward wind speed the phase speed of the tads was much faster 1100 m s in the model probably due to the overestimation of joule heating in the model the second tad corresponds to the observed prominent tid while signatures of the first tad were also seen in the observed ionosonde data the observed tid was characterized by a decrease in southward wind speed causing a significant f layer height decrease and a temporal enhancement of f layer peak density these characteristics were reproduced by the model as a rarefaction of the second tad the temporal enhancement of f layer peak density was because of the vertical shear of meridional wind the absolute value of f layer electron density in the model was several factors smaller than that observed probably because of the underestimation of the supply of o ions from the plasmasphere

some measurements of the permeability of kaolin this paper reports an experimental investigation of the vertical and horizontal permeabilities of speswhite kaolin clay the permeabilities were measured using falling head permeability tests a mo

influence of particle shape on the frictional strength of sediments a numerical case study abstract numerous direct and ring shear tests supply that composition and texture of sediments are crucial for shear and frictional strength we simulate particle interactions on a micro scale level during shearing with a numerical shear box using the discrete element method dem based on the granular model approach detailed information about slip localisation and rates forces at particle contacts as well as particle rotation can be quantified as function of particle shape stress conditions and shear rate our numerical experiments show that the deformation behaviour of clay is largely controlled by their particle shape two key factors sphericity and roughness could be identified as relevant for frictional strength shear zone development and particle rotation with sphericity dominating over roughness decreasing sphericity leads to complex initial microfabrics whose breakdown with increasing strain is caused by particle rotation preferred particle orientation favours low friction decreasing volume strain and the evolution of particle domains of similar orientation decreasing roughness results in particle interlocking of different degrees which obstructs slip and rotation to preferred orientations so that friction is high and volume strain positive spatial and temporal shear zone development depends on the roughness of particles increasing roughness precludes shear zone development and particle domain evolution shear zone localisation depends on particle sphericity increasing sphericity leads to more localised but vertically dilated deformation

damping of large scale traveling ionospheric disturbances detected with gps networks during the geomagnetic storm 1 large scale traveling ionospheric disturbances lstids during the geomagnetic storm on 22 september 1999 were studied using total electron content tec data from the gps earth observation network geonet in japan international gps service igs and continuously operating reference stations cors in the united states the damping rates of the lstids were precisely derived in several local time sectors and were found to depend on values of the background tec this indicates that the dominant physical mechanism of the lstids damping is the ion drag effect by the background ionosphere the high resolution tec data from geonet revealed that two successive lstids were damped significantly as they traveled equatorward in the dawn sector the ratio of the perturbation component of tec to the background component i i0 decreased exponentially with the damping rate of 0 89 1000 km and 0 77 1000 km we studied also the amplitude of i i0 at high latitudes using igs data and found that the damping rates of lstids at high latitudes tended to be smaller than those at midlatitudes global tec observations during this geomagnetic storm by the igs and cors networks detected that several lstids propagated also equatorward in the afternoon sector and in the night sector the lstids in the afternoon sector were most damped with the damping rate of 1 04 1000 km which corresponds to the e folding length of 961 km the damping rate of lstids in the night sector was found to be small the lstids had a tendency to be damped rapidly in the regions where background tec was large this dependence of the damping rate on latitude and local time indicates that this intense damping of lstids was caused mainly by the ion drag effect that is proportional to the ion collision frequency the relation between the damping rates and the background tec derived from the observation are consistent with those estimated with a theoretical calculation of the gravity wave damping by the ion drag effect the worldwide distribution of gps receivers enabled us to estimate the longitudinal extent of these lstids the zonal width of lstids in the dawn sector was narrower than 45 in longitude 2 900 km around 55 n and wider than 20 in longitude 1 800 km around 40 n these widths were narrower than those reported in previous studies

late holocene earthquakes on the toe jam hill fault seattle fault zone bainbridge island washington five trenches across a holocene fault scarp yield the first radiocarbon measured earthquake recurrence intervals for a crustal fault in western washington the scarp the first to be revealed by laser imagery marks the toe jam hill fault a north dipping backthrust to the seattle fault folded and faulted strata liquefaction features and forest soil a horizons buried by hanging wall collapse colluvium record three or possibly four earthquakes between 2500 and 1000 yr ago the most recent earthquake is probably the 1050 1020 cal calibrated yr b p a d 900 930 earthquake that raised marine terraces and triggered a tsunami in puget sound vertical deformation estimated from stratigraphic and surface offsets at trench sites suggests late holocene earthquake magnitudes near m7 corresponding to surface ruptures 36 km long deformation features recording poorly understood latest pleistocene earthquakes suggest that they were smaller than late holocene earthquakes postglacial earthquake recurrence intervals based on 97 radiocarbon ages most on detrital charcoal range from 12 000 yr to as little as a century or less corresponding fault slip rates are 0 2 mm yr for the past 16 000 yr and 2 mm yr for the past 2500 yr because the toe jam hill fault is a backthrust to the seattle fault it may not have ruptured during every earthquake on the seattle fault but the earthquake history of the toe jam hill fault is at least a partial proxy for the history of the rest of the seattle fault zone

on the hydro mechanical behaviour of remoulded and natural opalinus clay shale the geo energy sector makes use of advanced technologies such as shale gas extraction co2 sequestration and nuclear waste geological disposal that rely on the exploitation of shale formations due to the great depths involved in these applications and the difficulties in retrieving intact samples remoulded shale specimens are often adopted for hydro mechanical testing remoulded and intact shales may substantially differ in their hydro mechanical behaviour due to the particular structure of the natural material which is the result of diagenesis and burial history this paper presents an experimental campaign aimed at i characterizing the role of diagenesis and depth for opalinus clay shale and their impact on the hydro mechanical behaviour of the material and ii understanding how representative the behaviour of the remoulded material is with respect to that of the natural shale in this paper the hydro mechanical behaviour of remoulded and intact specimens from the opalinus clay shale formation is investigated by means of a comprehensive oedometric testing campaign the effects of depth and diagenesis on the material behaviour are analysed by testing intact specimens that come from two different sites and depths of the considered shale formation the results highlight a considerably greater stiffness for the natural opalinus clay with respect to the remoulded specimens when the same vertical effective stress is considered together with a significantly lower porosity for the former which is shown to be the result of diagenetic processes rather than solely mechanical compaction a lower swelling sensitivity is also manifested by the natural material with respect to the remoulded specimens as a result of the formation of bonding on the other hand the diagenetic processes do not seem to have a strong impact on the permeability of the material finally creep effects are reduced when diagenesis occurs while they become more relevant when the material is disturbed or remoulded the obtained results provide significant insight into the roles of depth diagenesis and structural disturbance on the hydro mechanical behaviour of the opalinus clay shale

stress state permeability relations for overconsolidated clays analysis of experimental data of soils in both the normally consolidated and overconsolidated states reveal that the proposed relationships are tenable preconsolidation stress level influences the level of permeability