fault reactivation in brittle viscous wrench systems dynamically scaled analogue models and application to the rhine bresse transfer zone abstract analogue experiments on oblique rifting and subsequent transpressional reactivation were performed with two layer slabs of sand and silicone in this brittle viscous system transtensional and transpressional wrench faulting was induced by movements of a basal rigid plate the dynamically scaled analogue models are confronted with the structural evolution of the rhine bresse transfer zone rbtz that linked palaeogene rifting in the upper rhine and bresse grabens and that appears to have been transpressively reactivated in neogene to recent times fault patterns produced in the sand layer above the basal silicone layer are compared with structural elements in the sedimentary cover separated from the basement by an evaporitic decollement layer in order to investigate strain rate dependence of fault reactivation and graben inversion transpressional shortening was performed under different displacement rates experimental results suggest that the reactivation of pre existing structures in a brittle cover above a viscous decollement is strongly dependent on the strain rate within the viscous layer under low to intermediate displacement rates 2 6 cm h 1 deformation concentrates within the basal viscous layer and former normal faults within the cover are not reactivated the reactivation at higher displacement rates 5 cm h 1 results in a complete inversion of graben structures within the cover ongoing shortening produces lobed thrust fronts which crosscut pre existing normal faults late pliocene to recent en echelon aligned folds and isolated thrust faults in the cover of the rbtz are attributed to thick skinned reactivation of basement faults a comparison of natural and experimentally obtained structures suggests that fault reactivation occurred under low displacement rates

rupture kinematics of the 2005 mw 8 6 nias simeulue earthquake from the joint inversion of seismic and geodetic data the 2005 mw 8 6 nias simeulue earthquake was caused by rupture of a portion of the sunda megathrust offshore northern sumatra this event occurred within an array of continuous global positioning system gps stations and produced measurable vertical displacement of the fringing coral reefs above the fault rupture thus this earthquake provides a unique opportunity to assess the source character istics of a megathrust event from the joint analysis of seismic data and near field static co seismic displacements based on the excitation of the normal mode data and geodetic data we put relatively tight constraints on the seismic moment and the fault dip where the dip is determined to be 8 to 10 with corresponding moments of 1 24 10 22 to 1 00 10 22 n m respectively the geodetic constraints on slip distribution help to eliminate the trade off between rupture velocity and slip kine matics source models obtained from the inversion of various combinations of the teleseismic body waves and geodetic data are evaluated by comparing predicted and observed long period seismic waveforms 100 500 sec our results indicate a rela tively slow average rupture velocity of 1 5 to 2 5 km sec and long average rise time of up to 20 sec the earthquake nucleated between two separate slip patches one beneath nias and the other beneath simeulue island the gap between the two patches and the hypocentral location appears to be coincident with a local geological disrup tion of the forearc coseismic slip clearly tapers to zero before it reaches the trench probably because the rupture propagation was inhibited when it reached the accre tionary prism using the models from joint inversions we estimate the peak ground velocity on nias island to be about 30 cm sec an order of magnitude slower than for thrust events in continental areas this study emphasizes the importance of util izing multiple datasets in imaging seismic ruptures

rheology of the earth s mantle a historical review abstract historical development of our understanding of rheological properties of the earth s mantle is reviewed rheological properties of the earth s mantle control most of the important geological processes such as the style of mantle convection e g stagnant lid versus plate tectonics and the nature of thermal evolution however inferring the rheological properties of the earth s mantle is challenging because of the presence of multiple mechanisms of deformation that have different dependence on time scale strain rate stress levels and other parameters through the integration of a broad range of observations including the elastic stiffness from tidal deformation and the viscosity from the concept of isostasy a gross picture of rheological stratification of the earth s mantle a strong lithosphere a weak asthenosphere and a strong layer below was proposed in the mid 19th century however not only the physical basis for such a model was weak due to the lack of proper understanding of some materials science issues such as the interplay between elastic and viscous deformation but also the lack of understanding of temperature depth relation associated with convection prevented our understanding of the rheological structure of the earth s interior major progress occurred in the first half of the 20th century in our understanding of the atomistic mechanisms of plastic deformation in solids and much of the theoretical framework on the plastic deformation of solids was established by late 1960s those developments provided a basis for scaling analyses that are critical to the applications of laboratory results to the earth s interior major progress in laboratory studies on rheological properties occurred in the mid 1960s to the early 1970s in griggs lab using a new type of solid medium high pressure deformation apparatus to pressure 2 gpa and temperature 1600 k the basic concepts such as the water weakening non linear rheology and deformation induced lattice preferred orientation were identified by their studies however large uncertainties in the stress measurements with this type of apparatus were recognized in the late 1970s and high resolution experimental studies using synthetic samples were initiated in paterson s lab in the mid 1980s using a high resolution gas medium deformation apparatus however experimental studies with such a gas medium deformation apparatus can be conducted only at low pressures

evolution of terrace risers along the upper rhine graben inferred from morphologic dating methods evidence of climatic and tectonic forcing summary we show that morphologic dating techniques that have been applied successfully in arid and semi arid areas are also suitable for slowly evolving scarps that are usually found in temperate climate environments we have attempted two morphologic approaches based on diffusion to relate the present day shape of an abandoned terrace riser to its age the first assumes a model of scarp degradation based on a diffusive process the d method the second evaluates the state of scarp degradation using the slope distribution the sd method along a topographic profile by using a manmade scarp of known age we have obtained a mass diffusivity close to 1 4 m2 ka 1 when the area experiences a temperate climate characterized by a continuous vegetation cover however this value decreases during glacial episodes probably on account of the permafrost even though the sd method requires an age correction that can be easily computed only this method reveals that at several profiles a later scarp reactivation event has occurred indeed along several profiles the slope distribution was best fitted by two offset gaussian curves suggesting that some scarps have undergone a complex evolution that cannot be modelled with a single diffusive process this scarp reactivation may correspond to a new incisive episode and allows one to estimate the vertical incision rate along the terrace riser applied to a wurmian terrace riser of the upper rhine valley ne france this approach reveals that the vertical incision rate ranges from 0 2 to 0 85 mm yr 1 between 35 and 15 ka and that the terrace bevelling occurred during two episodes related to climatic forcing moreover we can identify a component of tectonic forcing evidenced by an increase to the north of vertical incision rate and rhine stream power another major result is showing that this terrace riser is not isochronous along its strike and that younger portions result from lateral incision of a 30 ka pre existing scarp

global anisotropy in the upper mantle inferred from the regionalization of phase velocities a data set of 2600 paths for rayleigh waves and 2170 paths for love waves was selected in order to resolve azimuthal anisotropy of surface waves in the period range 70 250 s the epicenters were chosen so that the paths provide uniform spatial and azimuthal coverage of earth a synthetic seismogram is computed for each path and compared to the observed seismogram in order to infer the phase velocity along each path to process such a large data set a new tomographic technique is designed a good correlation is found with surface tectonics in the whole period range for love waves and at shorter periods for rayleigh waves the directions of maximum velocities are also well correlated with plate tectonics motions for the 2 azimuthal term of rayleigh waves when the power spectrum of heterogeneities is computed it is found that for love waves the even orders are usually larger than the odd orders for rayleigh waves the degrees 2 and 6 dominate only at long periods suggesting a deep origin for these components

comparative tertiary stratigraphy of the rhine graben bresse graben and molasse basin correlation of alpine foreland events abstract comparative tectonostratigraphic analysis of the tertiary middle eocene pliocene of the rhine bresse graben system and the western molasse basin demonstrates the occurrence of eleven correlative sequences crf i xi these show a close relationship between intra basinal tectonics and depositional history their punctuated sediment accumulation can be related to phases of extra alpine taphrogenesis and alpine orogenesis and to coeval eustatic changes in sea level apparent simultaneity in rift and foredeep sequence development structural deformation and global change in sea level suggests a common causal control in which the development of the alps played an important role

transient creep in natural and synthetic iron bearing olivine single crystals mechanical results and dislocation microstructures abstract this study examines transient creep of single crystals of both natural and synthetic iron bearing olivine under uniaxial compression 0 1 mpa confining pressure and loads of 25 30 mpa at high temperature 1650 k and controlled oxygen fugacity natural samples were obtained from san carlos arizona and synthetic crystals were grown at lawrence livermore national laboratory samples were deformed in the 110 c and 101 c orientations corresponding to the softest and intermediate strength orientations respectively as determined from steady state creep tests dislocation microstructures were examined for samples unloaded at 0 0 1 0 5 and 5 strain at 0 strain the dislocation density and morphology were lower and less complex in the synthetic olivine than in san carlos samples nearly all microstructures initially present in undeformed material were overwritten by 0 1 strain with further straining little change in microstructure occurred to the 5 strain limit tested here dislocation microstruc tures in 101 c samples were consistent with the activation of the 100 001 and 001 100 slip systems microstruc tures formed in 110 c samples matched those expected from activation of a single slip system 100 010 these slip systems are the same as those identified as responsible for steady state creep under similar temperature oxygen fugacity and stress conditions both natural and synthetic crystals deformed under constant stress in 101 c showed normal strain hardening with initial strain rates about an order of magnitude higher than those at 5 strain after an initial high strain rate that was roughly equal in both sample types the synthetic samples deformed at higher rates than the natural crystals crystals in the 110 c orientation deformed in a strikingly different manner san carlos olivine showed inverse or strain softening creep in the first 1 2 strain after which there is weak evidence suggesting a change to strain hardening behavior the temporal strain behavior of synthetic olivine in 110 c is strongly sigmoidal an inflection point at 1 strain marks the change from inverse to normal transient creep in the 110 c orientation steady state creep was not attained for synthetic samples in the 5 strain limit tested here these results imply that anisotropic transient creep may exist in the upper mantle complicating rheological models of post glacial rebound the transient creep observed in the 110 c orientation illustrates that the strain hardening burgers body model is not universally applicable the 100 010 slip system is not always the softest system in the transient regime strain may initially be accommodated primarily in the 100 001 001 100 duplex system finally the transient regime has been shown to extend to several percent strain in the 110 c orientation making transient creep potentially important in modelling initial post glacial rebound

three dimensional models of elastostatic deformation in heterogeneous media with applications to the eastern california shear zone summary we present a semi analytic iterative procedure for evaluating the 3 d deformation due to faults in an arbitrarily heterogeneous elastic half space spatially variable elastic properties are modelled with equivalent body forces and equivalent surface traction in a homogenized elastic medium the displacement field is obtained in the fourier domain using a semi analytic green function we apply this model to investigate the response of 3 d compliant zones cz around major crustal faults to coseismic stressing by nearby earthquakes we constrain the two elastic moduli as well as the geometry of the fault zones by comparing the model predictions to synthetic aperture radar inferferometric insar data our results confirm that the cz models for the rodman calico and pinto mountain faults in the eastern california shear zone ecsz can explain the coseismic insar data from both the landers and the hector mine earthquakes for the pinto mountain fault zone insar data suggest a 50 per cent reduction in effective shear modulus and no significant change in poisson s ratio compared to the ambient crust the large wavelength of coseismic line of sight displacements around the pinto mountain fault requires a fairly wide 1 9 km cz extending to a depth of at least 9 km best fit for the calico cz north of galway dry lake is obtained for a 4 km deep structure with a 60 per cent reduction in shear modulus with no change in poisson s ratio we find that the required effective rigidity of the calico fault zone south of galway dry lake is not as low as that of the northern segment suggesting along strike variations of effective elastic moduli within the same fault zone the ecsz insar data is best explained by cz models with reduction in both shear and bulk moduli these observations suggest pervasive and widespread damage around active crustal faults

steady state laboratory flow laws alone fail to explain postseismic observations abstract we test whether laboratory derived steady state flow laws for wet olivine can be used to explain postseismic relaxation in the upper mantle following the 1999 hector mine earthquake this is accomplished using rate changes in gps observed displacement time series at far field stations as constraints on the parameters associated with laboratory derived temperature and stress dependent flow laws for diffusion and dislocation creep of olivine we primarily concentrate on the influences of temperature grain size and background strain rate to explain observed fast early displacement rates that slow rapidly in the 7 years of postseismic observations we find that a reasonable fit to the observed time series cannot be achieved by any combination of flow law parameters and plausible assumptions for the tectonic environment of the mantle beneath the mojave desert we conclude that postseismic relaxation within the mantle following the hector mine earthquake likely includes an initial transient weakening phase suggesting that steady state flow laws by themselves are insufficient to characterize the flow of mantle rocks when stress conditions evolve

mechanisms of shear localization in the continental lithosphere inference from the deformation microstructures of peridotites from the ivrea zone northwestern italy the ultramafic massif of balmuccia northwestern italy shows a variety of deformation fabrics including some localized shear zones that resulted in nearly complete melting pseudotachylyte a series of peridotite specimens were collected near one of the pseudotachylyte fault veins to investigate the mechanisms of shear localization the microstructural analyses show at least three deformation stages the first stage i is nearly homogeneous deformation at low stress 3 mpa and high temperature 1300 1500 k followed by localized deformation stage ii at a higher stress 60 mpa and moderate temperature 1000 1150 k and finally semi brittle deformation stage iii at a very high stress 400 mpa that resulted in the formation of pseudotachylyte the stage ii deformation resulted in relatively small strains in most areas but significant localized deformation leading to dynamic recrystallization occurred the degree of which increases systematically toward the fault zone based on this observation together with the observation that the brittle deformation post dated dynamic recrystallization we conclude that the shear localization in this locality occurred as a result of ductile deformation rather than brittle deformation various mechanisms of shear localization in the ductile regime are examined and we conclude that the grain size reduction due to dynamic recrystallization at relatively high stresses and moderate temperatures is a probable mechanism of shear localization the intermediate regime between dislocation and diffusion creep where rheology is grain size sensitive yet continuous recrystallization occurs due to dislocation creep is suggested to play an important role in shear localization in the upper mantle the conditions of shear localization due to this mechanism are examined based on the laboratory data on creep and dynamic recrystallization it is shown that shear localization occurs at relatively low temperatures and or high stresses localized deformation in the continental lithosphere will occur well below the brittle ductile transition 10 km depth down to 40 80 km depth depending upon the geothermal gradient and water fugacity

river response to an active fold and thrust belt in a convergent margin setting north island new zealand high resolution digital elevation data topsar 10 m grid are used to reconstruct late quaternary growth histories of subtle folding in the wairarapa fold and thrust belt north island new zealand outcrop data of deformed latest miocene and younger strata are combined with observations of warped and faulted late quaternary terrace surfaces to unravel the geomorphic and structural history of the huangarua river valley optically stimulated luminescence osl dating of loess that accumulated on these strath terraces and paleosol stratigraphy allow temporal correlation among the terraces and with glacial climate cycles since the last interglaciation these data indicate that five intervals of strath cutting occurred at 125 60 70 30 15 and 10 ka strath beveling is largely independent of local folding or regional base level change we hypothesize that straths are cut when an increase in sediment supply during cool climatic periods brings river sediment load and river transport capacity into balance in the wairarapa strath cutting events appear to occur near the end of cool climatic cycles this study shows that the identification of subtle departures from regional topographic trends becomes practical when a high resolution dem is available after subtraction of an average valley gradient from the digital topography the residual topography on the terrace treads reveals cross valley and longitudinal tilting although rates of folding are slow and the magnitude of deformation is commonly limited to less than a few tens of meters these topographic anomalies define fold axes that coincide with subsurface structures when combined with time control these anomalies serve to define the patterns and rates of fold growth over the past 125 kyears

alluvial plains formation in response to 100 ka glacial interglacial cycles since the middle pleistocene in the southern tian shan nw china abstract the tenet of the milankovitch theory is that northern hemisphere solar insolation controlled by earth s orbital is responsible for cyclic climate variations eccentricity in this context is responsible for cyclic variability of 100 ka and may drive periodicity in climate change during the middle and late pleistocene although abundant evidence exists for 100 ka cyclic climatic fluctuations driving glacial interglacial cycles our knowledge about the record of cyclic climatic changes preserved in terrestrial landscapes remains limited especially over multi millennial several glacial interglacial timescales the intermontane yanqi basin in the southeastern tian shan central asia preserves at least seven generations of alluvial surfaces spanning multiple glacial cycles and yields insights into the record of climatic fluctuations that lead to aggradation and incision of river systems we complement existing chronologic data with two new cosmogenic 10be depth profiles and four surface exposure ages of alluvial surface abandonment in the south tian shan piedmont within the yanqi basin new surface exposure dating reveals the successive abandonment of these surfaces with a 100 ka cyclicity between 5 1 0 9 and 550 ka and indicates that there were multiple aggradation incision cycles the superimposed 100 ka cycles of aggradation incision are best explained by eccentricity driven climate change within these cycles sediment is produced during glaciations by glacial and periglacial erosion however due to the dry and cold conditions of the glacial periods in central asia there is little discharge available to transport and evacuate the sediment from the valleys to the piedmont later during the glacial to interglacial transition higher precipitation and high discharge due to glacial melt water resulted in higher transport capacity of the river beyond a threshold to evacuate sediment subsequent rapid incision occurs after the upstream sediment reservoir is depleted and its timing corresponds to the glacial to interglacial transition period in our study area compared with the aggradation and incision of the northern piedmont of the tian shan governed by the westerlies the sedimentary systems of the south tian shan piedmont within the yanqi basin are mainly controlled by eccentricity driven glacial interglacial cycles

en echelon and orthogonal fault ruptures of the 11 april 2012 great intraplate earthquakes the magnitude 8 7 earthquake that occurred off the coast of the sumatra subduction zone on 11 april 2012 is shown to have had an extraordinarily complex four fault rupture these great ruptures represent large lithospheric deformation that may eventually lead to a localized boundary between the indian and australian plates on 11 april 2012 two of the largest strike slip earthquakes ever recorded at magnitudes of 8 7 and 8 2 occurred in the northeastern indian ocean a few hundred kilometres off the coast of sumatra three groups now report the analysis of seismic data from the days and months before and after these events as well as the events themselves matthias delescluse and co authors show that these earthquakes are part of the ongoing boost of intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes they conclude that the australian plate driven by slab pull forces at the sunda trench is gradually detaching from the indian plate han yue and colleagues show that the 11 april event involved a complex four fault rupture lasting several minutes followed two hours later by a magnitude 8 2 aftershock these great ruptures on a lattice of strike slip faults that extends through the crust and into the upper mantle represent large lithospheric deformation that may eventually create a localized boundary between the indian and australian plates fred pollitz and colleagues show that in the six days following 11 april the global rate of remote earthquakes with magnitudes greater than 5 5 increased nearly fivefold and events up to magnitude 7 seem to have been triggered the unprecedented delayed triggering power of this earthquake may arise from its strike slip source geometry or because it struck at a time of an unusually low global earthquake rate and increased the number of nucleation sites that were very close to failure the indo australian plate is undergoing distributed internal deformation caused by the lateral transition along its northern boundary from an environment of continental collision to an island arc subduction zone1 2 on 11 april 2012 one of the largest strike slip earthquakes ever recorded seismic moment magnitude mw 8 7 occurred about 100 200 kilometres southwest of the sumatra subduction zone occurrence of great intraplate strike slip faulting located seaward of a subduction zone is unusual it results from northwest southeast compression within the plate caused by the india eurasia continental collision to the northwest together with northeast southwest extension associated with slab pull stresses as the plate underthrusts sumatra to the northeast here we use seismic wave analyses to reveal that the 11 april 2012 event had an extraordinarily complex four fault rupture lasting about 160 seconds and was followed approximately two hours later by a great mw 8 2 aftershock the mainshock rupture initially expanded bilaterally with large slip 20 30 metres on a right lateral strike slip fault trending west northwest to east southeast wnw ese and then bilateral rupture was triggered on an orthogonal left lateral strike slip fault trending north northeast to south southwest nne ssw that crosses the first fault this was followed by westward rupture on a second wnw ese strike slip fault offset about 150 kilometres towards the southwest from the first fault finally rupture was triggered on another en echelon wnw ese fault about 330 kilometres west of the epicentre crossing the ninetyeast ridge the great aftershock with an epicentre located 185 kilometres to the ssw of the mainshock epicentre ruptured bilaterally on a nne ssw fault the complex faulting limits our resolution of the slip distribution these great ruptures on a lattice of strike slip faults that extend through the crust and a further 30 40 kilometres into the upper mantle represent large lithospheric deformation that may eventually lead to a localized boundary between the indian and australian plates

river incision and terrace formation in the late cenozoic of europe abstract late cenozoic environmental changes which affected european rivers are reviewed focusing especially on those of mid pleistocene times c 1 2 0 8 ma or around mis 22 and thereafter these involved dominating but fluctuating cold climate periglacial conditions shorter but major episodes of glaciation and brief interglacials there were also related sea level and tectonic responses the known history of european rivers in this period is individually varied but is predominantly marked by multiple stages of episodic incision the form of which changed in style at around the mid pleistocene transition it is suggested that the nature of climatic oscillations the dating of incision episodes and the processes that achieve this incision are as yet insufficiently understood fluvial process studies suggest that the onset of incision may broadly relate to changes in slope discharge sediment load and calibre and bedrock erodibility and these may all have been transformed as the direct or indirect result of mid pleistocene climatic changes common properties of basal sediments on strath terraces suggest that it was during the extended but variable cold stage episodes that both valley deepening and lateral widening occurred and that climatic change was the principal driver of episodic deep valley incision

upper mantle water stratification inferred from observations of the 2012 indian ocean earthquake postseismic recordings of the moment magnitude 8 6 indian ocean earthquake of 2012 combined with the characteristics of olivine creep provide constraints on the water content of the asthenosphere sylvain barbot and colleagues infer that observed transient deformation in the aftermath of the 2012 indian ocean earthquake as recorded by continuous geodetic stations in the region requires a minimum olivine water content of about 0 01 per cent by weight in the oceanic asthenosphere the earthquake ruptured conjugate faults throughout the entire overlying oceanic lithosphere down to great depths compatible with dry olivine in the upper layer the authors explain the rheological contrast by dehydration across the lithosphere asthenosphere boundary presumably by buoyant melt migration that formed the oceanic crust elsewhere in this issue of nature yan hu et al use observations of postseismic deformation following this earthquake to constrain the structure of oceanic mantle rheology water the most abundant volatile in earth s interior preserves the young surface of our planet by catalysing mantle convection lubricating plate tectonics and feeding arc volcanism since planetary accretion water has been exchanged between the hydrosphere and the geosphere but its depth distribution in the mantle remains elusive water drastically reduces the strength of olivine1 and this effect can be exploited to estimate the water content of olivine from the mechanical response of the asthenosphere to stress perturbations such as the ones following large earthquakes here we exploit the sensitivity to water of the strength of olivine2 the weakest and most abundant mineral in the upper mantle and observations of the exceptionally large moment magnitude 8 6 2012 indian ocean earthquake3 to constrain the stratification of water content in the upper mantle taking into account a wide range of temperature conditions and the transient creep of olivine we explain the transient deformation in the aftermath of the earthquake that was recorded by continuous geodetic stations along sumatra as the result of water and stress activated creep of olivine this implies a minimum water content of about 0 01 per cent by weight or 1 600 h atoms per million si atoms in the asthenosphere the part of the upper mantle below the lithosphere the earthquake ruptured conjugate faults down to great depths4 compatible with dry olivine in the oceanic lithosphere we attribute the steep rheological contrast to dehydration across the lithosphere asthenosphere boundary presumably by buoyant melt migration to form the oceanic crust

climate forcing of fluvial system development an evolution of ideas starting from traditional ideas on the climatic steering of fluvial system dynamics it appears that there are different kinds of climatic influences on system dynamics they vary from direct climatic forcing like peak precipitation to indirect like permafrost and partial forcing like vegetation vegetation or its absence and not directly climate is considered as the main cause of fluvial incision or deposition during temperate or cold periods however other external factors than climate and non climatic factors such as local basin characteristics like subsoil lithology and relief express their effects on the fluvial systems by their role in the energy balance of the river catchment finally internal factors in fluvial system evolution like thresholds and response time should not be neglected

reflection of the glacial interglacial cycle in the evolution of the vistula river basin poland a variety of factors has controlled the evolution of the vistula river valley they include climatically induced changes of the river runoff and sediment load glacial advances and rapid variations of the base level as well as the influence of the tectonic factor the first order climatic cycles are reflected in separate terrace fills the second order fluctuations may be represented by separate cuts and fills by the change of the facies or by the change in the granulometric composition the analysis of the changes in the longitudinal profile helped to discover a great variety of different valley reaches and a general tendency to smooth the long profile during the quaternary

fluvial system response to middle and upper pleistocene climate change in the meurthe and moselle valleys eastern paris basin and rhenish massif abstract research in the meurthe and moselle valleys downstream from the vosges massif has resulted in the definition of the terrace system and in the recognition of the climatic influence on its formation eight alluvial terraces were recognized at less than 100 m relative height an absolute chronology was established for the youngest alluvial terraces based on infrared optically stimulated luminescence and radiocarbon dating this provides evidence that each terrace corresponds to a single glacial interglacial cycle this result is confirmed by the study of numerous sections which present a constant succession of lithofacies in each valley part four alluvial sequences were also defined along the meurthe and moselle valleys reflecting middle and late pleistocene climate change their upper basin developed in the vosges massif was actually covered by glaciers during the pleistocene cold periods the differences between these four alluvial sequences are attributed to the unequal expansion of ice in the upper basins of the meurthe and moselle rivers and their tributaries in spite of these differences the sequences show important similarities main aggradation events correlate with cold periods pleniglacial and lateglacial whereas erosional phases occurred at the warm to cold transitions and secondarily at the pleniglacial lateglacial transitions this evolution is comparable with those already described in other northwestern european valleys especially since the upper saalian

on the mechanics of earthquake afterslip we propose a model for earthquake afterslip based on rate and state variable friction laws in the model afterslip is attributed to the interaction of a velocity weakening region at depth within which earthquakes nucleate with an upper region of velocity strengthening frictional behavior the existence of this upper region is supported by independent seismologic observations and the results of laboratory friction experiments in our model afterslip is the result of relaxation of a stress perturbation within the velocity strengthening region which arises when an earthquake propagates into that region from below we derive the stress perturbation and its decay from the friction constitutive law using a simple 1 degree of freedom approximation for the elastic interaction between the fault and its surroundings this approximation is based on thickness averaged displacements and slip velocities within the velocity strengthening region which is assumed to slip as a rigid block coseismic and postseismic slip are coupled through the thickness averaged stiffness k of the velocity strengthening region we assume k to be inversely proportional to the thickness of this region which means that thicker velocity strengthening regions have a greater tendency to arrest coseismic slip we model the afterslip time histories of the 1966 parkfield and 1987 superstition hills earthquakes and relate the model parameters to physical parameters which may govern the rheologic behavior of the faults in accord with field observations our model predicts 1 that afterslip on some faults scales with the thickness of the unconsolidated sedimentary cover and 2 that proportionally more afterslip occurs for earthquakes in which coseismic surface slip is small compared with coseismic slip at depth velocity strengthening frictional behavior is to be expected for faults within poorly consolidated sediments and for those that contain significant gouge zones about 500 m within their shallow regions 3 5 km combining our results with those of recent laboratory friction studies indicates that relatively young faults with little accumulated fault gouge should exhibit little afterslip

multiple fault reactivations within the intra continental rhine bresse transfer zone la serre horst eastern france abstract thermochronological structural and kinematic analyses demonstrate the influence of late paleozoic basement structures on the localization and evolution of the rhine bresse transfer zone rbtz a central segment of the european cenozoic rift system zircon and apatite fission track data indicate that the paleozoic crystalline basement and its permo triassic cover exposed in the la serre horst experienced a middle jurassic to early cretaceous heating event which was followed by two distinct periods of cooling a first cooling event occurred in the early cretaceous and is probably related to thermal relaxation a second one started at around 38 ma is interpreted to reflect exhumation that was induced by fault reactivation along the late paleozoic burgundy trough system during eocene oligocene rifting and the formation of the rbtz this fault reactivation resulted in a complex fault pattern and local stress field perturbations in the surroundings of the pre existing horst structure substantial extension was achieved by ene wsw striking normal faults that trend highly oblique to the dominant strike of the rhine and bresse graben rifts seismic reflection data show that these major normal faults are typically associated with extensional flexures and oriented parallel to pre existing late paleozoic basement faults of the burgundy trough paleostress analyses yield overall nw se extension during the eo oligocene slightly oblique to the structural trend of the rbtz and additionally local stress field perturbations induced by the reactivation of pre existing faults reactivation of paleozoic structures in the rbtz is of extensional rather than of strike slip character indicating that the rbtz is forming a separate oblique graben segment within the european cenozoic rift system rather than a sinistral strike slip transform zone supposedly connecting rhine and bresse graben structures

evidence for an early glacial maximum in the french vosges during the last glacial cycle the last glacial maximum is observed to have occurred between 18 000 and 20 000 years ago throughout northern europe here we present evidence for the surprising result that in the region of the french vosges the regional ice sheet advanced during the early part of the last glacial cycle and this expansion was considerably larger than that which occurred during the last glacial maximum from these results we conclude that the glacial maximum may not have occurred at the same time worldwide contrary to what has usually been assumed1

climate related river activity at the weichselian holocene transition a comparative study of the warta and maas rivers huvial systems from the dutch and polish lowlands are compared for their evolution during the weichselian deglaciation period in both regions the pleniglacial braided river pattern changed to a meandering pattern in the beginning of the lateglacial several transitional stages between braided and high sinuosity meandering systems have been recognized a difference in fluvial activity is found during the younger dryas when the maas transformed to a braided pattern while the warta maintained its meandering pattern phases of erosion and aggradation are more or less synchronous in the different river basins but their intensity may differ greatly the major characteristics of the fluvial systems are obviously a response to the general climatic evolution and related to changes in vegetation the regional differences are of minor importance and can be explained by site specific factors threshold values within the latter factors define the changes in river dynamics

rheology of the upper mantle a synthesis rheological properties of the upper mantle of the earth play an important role in the dynamics of the lithosphere and asthenosphere however such fundamental issues as the dominant mechanisms of flow have not been well resolved a synthesis of laboratory studies and geophysical and geological observations shows that transitions between diffusion and dislocation creep likely occur in the earth s upper mantle the hot and shallow upper mantle flows by dislocation creep whereas cold and shallow or deep upper mantle may flow by diffusion creep when the stress increases grain size is reduced and the upper mantle near the transition between these two regimes is weakened consequently deformation is localized and the upper mantle is decoupled mechanically near these depths

feedback between erosion and active deformation geomorphic constraints from the frontal jura fold and thrust belt eastern france a regional tectono geomorphic analysis indicates a pliocene to recent rock uplift of the outermost segment of the jura fold and thrust belt which spatially coincides with the intra continental rhine bresse transfer zone elevated remnants of the partly eroded middle pliocene sundgau foret de chaux gravels identified by heavy mineral analyses allow for a paleo topographic reconstruction that yields minimum regional latest pliocene to recent rock uplift rates of 0 05 0 02 mm year this uplift also affected the pleistocene evolution of the ognon and doubs drainage basins and is interpreted as being tectonically controlled while the ognon river was deflected from the uplifted region the doubs deeply incised into it focused incision of the doubs possibly sustained ongoing deformation along anticlines which were initiated during the neogene evolution of the thin skinned jura fold and thrust belt at present this erosion related active deformation is taking place synchronously with thick skinned tectonics controlling the inversion of the rhine bresse transfer zone this suggests local decoupling between seismogenic basement faulting and erosion related deformation of the mesozoic cover sequences

postearthquake relaxation evidence for laterally variable viscoelastic structure and water content in the southern california mantle i reexamine the lower crust and mantle relaxation following two large events in the mojave desert the 1992 m7 3 landers and 1999 m7 1 hector mine california earthquakes time series from continuous gps sites out to 300 km from the ruptures are used to constrain models of postseismic relaxation crustal motions in the mojave desert region are elevated above background for several years following each event to account for broadscale relaxation of the lower crust and mantle the burgers body model is employed involving transient and steady state viscosities joint afterslip postseismic relaxation modeling of the gps time series up to one decade following the hector mine earthquake reveals a significant rheological contrast between a northwest trending southwest domain that envelopes the san andreas fault system and western mojave desert and an adjacent northeast domain that envelopes the landers and hector mine rupture areas in the central mojave desert the steady state viscosity of the northeast domain mantle asthenosphere is inferred to be 4 times greater than that of the southwest domain this pattern is counter to that expected for regional heat flow which is higher in the northeast domain but it is explicable by means of a nonlinear rheology that includes dependence on both strain rate and water concentration i infer that the southwest domain mantle has a relatively low steady state viscosity because of its high strain rate and water content the relatively low mantle water content of the northeast domain is interpreted to result from the continual extraction of water through igneous and volcanic activity over the past 20 myr

late quaternary climatic and tectonic mechanisms driving river terrace development in an area of mountain uplift a case study in the langshan area inner mongolia northern china abstract the langshan range is located in the western yin mountain orogenic belts and the western hetao fault depression zone in inner mongolia northern china this area is on the northwestern margin of the east asian monsoon region the fluvial terraces in the transverse drainage of the langshan range represent a primary geomorphic response to local tectonic uplift and climatic changes the terrace evolution was reconstructed using a combination of optically stimulated luminescence osl dating and terrace tread measurements the terraces designated t4 through t1 were abandoned at about 58 00 46 25 32 19 and 15 79 ka bp respectively their aggradation occurred primarily during cold periods of the last glacial stage and incision occurred primarily during shifts from cold to warm climate stages geomorphic analysis showed the terrace heights were controlled by the tectonic uplift in the area differences in river incision rates and terrace geomorphic features indicate that the uplift of the langshan range included a component of tilting north to south during the period of 58 00 41 28 ka bp whereas the uplift of the langshan area tended to be equal on a regional scale after 32 19 ka bp

the 2012 mw 8 6 wharton basin sequence a cascade of great earthquakes generated by near orthogonal young oceanic mantle faults we improve constraints on the slip distribution and geometry of faults involved in the complex multisegment mw 8 6 april 2012 wharton basin earthquake sequence by joint inversion of high rate gps data from the sumatran gps array sugar teleseismic observations source time functions from broadband surface waves and far field static gps displacements this sequence occurred under the indian ocean 400 km offshore sumatra the events are extraordinary for their unprecedented rupture of multiple cross faults deep slip large strike slip magnitude and potential role in the formation of a discrete plate boundary between the indian and australian plates the sugar recorded static displacements of up to 22 cm along with time varying arrivals from the complex faulting which indicate that the majority of moment release was on young wnw trending right lateral faults counter to initial expectations that an old lithospheric nne trending fracture zone played the primary role the new faults are optimally oriented to accommodate the present day stress field not only was the greatest moment released on the younger faults but it was these that sustained very deep slip and high stress drop 20 mpa the rupture may have extended to depths of up to 60 km suggesting that the oceanic lithosphere in the northern wharton basin may be cold and strong enough to sustain brittle failure at such depths alternatively the rupture may have occurred with an alternative weakening mechanism such as thermal runaway

coseismic slip and afterslip of the great mw 9 15 sumatra andaman earthquake of 2004 we determine coseismic and the first month postseismic deformation associated with the sumatra andaman earthquake of 26 december 2004 from near field global positioning system gps surveys in northwestern sumatra and along the nicobar andaman islands continuous and campaign gps measurements from thailand and malaysia and in situ and remotely sensed observations of the vertical motion of coral reefs the coseismic model shows that the sunda subduction mega thrust ruptured over a distance of about 1500 km and a width of less than 150 km releasing a total moment of 6 7 7 0 10 22 n m equivalent to a magnitude m w 9 15 the latitudinal distribution of released moment in our model has three distinct peaks at about 4 n 7 n and 9 n which compares well to the latitudinal variations seen in the seismic inversion and of the analysis of radiated t waves our coseismic model is also consistent with interpretation of normal modes and with the amplitude of very long period surface waves the tsunami predicted from this model fits rela tively well the altimetric measurements made by the jason and topex satellites neither slow nor delayed slip is needed to explain the normal modes and the tsunami wave the near field geodetic data that encompass both coseismic deformation and up to 40 days of postseismic deformation require that slip must have continued on the plate interface after the 500 sec long seismic rupture the postseismic geodetic moment of about 2 4 10 22 nm mw 8 8 is equal to about 30 5 of the coseismic moment release evolution of postseismic deformation is consistent with rate strengthening frictional afterslip online material summary of geodetic data used in this study

postseismic deformation following the 2010 m 7 2 el mayor cucapah earthquake observations kinematic inversions and dynamic models due to its location on a transtensional section of the pacific north american plate boundary the salton trough is a region featuring large strike slip earthquakes within a regime of shallow asthenosphere high heat flow and complex faulting and so postseismic deformation there may feature enhanced viscoelastic relaxation and afterslip that is particularly detectable at the surface the 2010 m 7 2 el mayor cucapah earthquake was the largest shock in the salton trough since 1892 and occurred close to the us mexico border and so the postseismic deformation recorded by the continuous gps network of southern california provides an opportunity to study the rheology of this region three year postseismic transients extracted from gps displacement time series show four key features 1 1 2 cm of cumulative uplift in the imperial valley and sim 1 cm of subsidence in the peninsular ranges 2 relatively large cumulative horizontal displacements 150 km from the rupture in the peninsular ranges 3 rapidly decaying horizontal displacement rates in the first few months after the earthquake in the imperial valley and 4 sustained horizontal velocities following the rapid early motions that were still visibly ongoing 3 years after the earthquake kinematic inversions show that the cumulative 3 year postseismic displacement field can be well fit by afterslip on and below the coseismic rupture though these solutions require afterslip with a total moment equivalent to at least a m 7 2 earthquake and higher slip magnitudes than those predicted by coseismic stress changes forward modeling shows that stress driven afterslip and viscoelastic relaxation in various configurations within the lithosphere can reproduce the early and later horizontal velocities in the imperial valley while newtonian viscoelastic relaxation in the asthenosphere can reproduce the uplift in the imperial valley and the subsidence and large westward displacements in the peninsular ranges we present two forward models of dynamically coupled deformation mechanisms that fit the postseismic transient well a model combining afterslip in the lower crust newtonian viscoelastic relaxation in a localized zone in the lower crust beneath areas of high heat flow and geothermal activity and newtonian viscoelastic relaxation in the asthenosphere and a second model that replaces the afterslip in the first model with viscoelastic relaxation with a stress dependent viscosity in the mantle the rheology of this high heat flow high strain rate region may incorporate elements of both these models and may well be more complex than either of them

earthquake cycle simulations with rate and state friction and power law viscoelasticity abstract we simulate earthquake cycles with rate and state fault friction and off fault power law viscoelasticity for the classic 2d antiplane shear problem of a vertical strike slip plate boundary fault we investigate the interaction between fault slip and bulk viscous flow with experimentally based flow laws for quartz diorite and olivine for the crust and mantle respectively simulations using three linear geotherms dt dz 20 25 and 30 k km produce different deformation styles at depth ranging from significant interseismic fault creep to purely bulk viscous flow however they have almost identical earthquake recurrence interval nucleation depth and down dip coseismic slip limit despite these similarities variations in the predicted surface deformation might permit discrimination of the deformation mechanism using geodetic observations additionally in the 25 and 30 k km simulations the crust drags the mantle the 20 k km simulation also predicts this except within 10 km of the fault where the reverse occurs however basal tractions play a minor role in the overall force balance of the lithosphere at least for the flow laws used in our study therefore the depth integrated stress on the fault is balanced primarily by shear stress on vertical fault parallel planes because strain rates are higher directly below the fault than far from it stresses are also higher thus the upper crust far from the fault bears a substantial part of the tectonic load resulting in unrealistically high stresses in the real earth this might lead to distributed plastic deformation or formation of subparallel faults alternatively fault pore pressures in excess of hydrostatic and or weakening mechanisms such as grain size reduction and thermo mechanical coupling could lower the strength of the ductile fault root in the lower crust and concomitantly off fault upper crustal stresses

seismic structure of the upper mantle in a central pacific corridor the seismic structure of the tonga hawaii corridor has been investigated by combining two data sets revenaugh and jordan s reflectivity profile from scs reverberations which provides travel times to and impedance contrasts across the major mantle discontinuities and 1500 new observations of frequency dependent phase delays for the three component s ss and sss body waves and the r1 and g1 surface waves which constrain the velocity structure within this layered framework the shear waves turning in the upper mantle showed significant splitting of the sh and sv components indicative of shallow polarization anisotropy the data set was inverted in conjunction with attenuation and mineralogical constraints to obtain a complete spherically symmetric radially anisotropic structure the final model pa5 is characterized by a high velocity anisotropic lid bounded at 68 km depth by a large negative g discontinuity a low velocity anisotropic layer below g extending to a small l discontinuity at 166 km an isotropic steep gradient region between 166 km and 415 km and transition zone discontinuities at 415 507 and 651 km the depth of the radial anisotropy in pa5 is shallower than in most previous studies based on surface waves and higher modes the average value of radial shear anisotropy in the lid 3 7 is consistent with the magnitude expected from the spreading controlled models of olivine orientation while anisotropy in the low velocity zone which is required by our data set could be induced either by paleostrains that took place near the ridge crest or by shearing in the asthenosphere as a result of present day plate motions on the basis of recent work by hirth and kohlstedt we suggest that the g discontinuity is caused by a rapid increase in the water content of mantle minerals with depth marking the fossilized lower boundary of the melt separation zone active during crust formation the high gradient zone between 200 and 400 km is a characteristic feature of convecting oceanic upper mantle and is probably controlled by a steady decrease in the homologous temperature over this depth interval the average shear velocity gradient in the transition zone is lower than in most previous seismic models in better agreement with the predictions for a pyrolitic composition

transient rheology of the uppermost mantle beneath the mojave desert california abstract geodetic data indicate that the m7 1 hector mine california earthquake was followed by a brief period a few weeks of rapid deformation preceding a prolonged phase of slower deformation we find that the signal contained in continuous and campaign global positioning system data for 2 5 years after the earthquake may be explained with a transient rheology quantitative modeling of these data with allowance for transient linear biviscous rheology in the lower crust and upper mantle demonstrates that transient rheology in the upper mantle is dominant its material properties being typified by two characteristic relaxation times 0 07 and 2 years the inferred mantle rheology is a jeffreys solid in which the transient and steady state shear moduli are equal consideration of a simpler viscoelastic model with a linear univiscous rheology 2 fewer parameters than a biviscous model shows that it consistently underpredicts the amplitude of the first 3 months signal and allowance for a biviscous rheology is significant at the 99 0 confidence level another alternative model deep postseismic afterslip beneath the coseismic rupture predicts a vertical velocity pattern opposite to the observed pattern at all time periods considered despite its plausibility the advocated biviscous rheology model is non unique and should be regarded as a viable alternative to the non linear mantle rheology model for governing postseismic flow beneath the mojave desert

long river profiles tectonism and eustasy a guide to interpreting fluvial terraces along three rivers at the mendocino triple junction northern california strath cut and fill terraces have formed in response to tectonic and eustatic processes detailed surveying and radiometric dating at multiple sites indicate that lower reaches of the rivers are dominated by the effects of oscillating sea level primarily aggradation and formation of fill terraces during sea level high stands alternating with deep incision during low stands a eustasy driven deposi tional wedge extends tens of kilometers upstream on all rivers tapering to zero thickness this distance is greater than expected from studies of the effects of check dams on much smaller streams elsewhere due in part to the large size of these rivers however the change in gradient is nearly identical to other base level rise studies the depositional gradient is about half that of the original channel middle to upper reaches of each fiver are dominated by the effects of long term uplift primarily lateral and vertical erosion and formation of steep unpaired strath terraces exposed only upstream of the depositional wedge vertical incision at a rate similar to that of uplift has occurred even during the present sea level high stand along rivers with highest uplift rates strath terraces have steeper gradients than the modem channel bed and do not merge with marine terraces at the river mouth consequently they cannot be used to determine altitudes of sea level high stands strath formation is a continuous process of response to long term uplift and its occurrence varies spatially along a river depending on stream power and hence position upstream strath terraces are found only along certain parts of a coastal stream upstream of the aggradational effects of oscillating sea level and far enough downstream that stream power is in excess of that needed to transport the prevailing sediment load for a given size fiver the greater the uplift rate the greater the rate of vertical incision and consequently the less the like lihood of strath terrace formation and preservation

late quaternary alluvial fan terraces langshan inner mongolia china abstract alluvial fan terraces of the langshan range in the northwestern hetao basin of northern china records uplift on range bounding faults and late quaternary climate change alluvial fan profiles are segmented in the central part of the range front which lack strath terraces that developed in the southwest sw and northeast ne parts the stream channels in the central part have higher channel gradients and lower ratios of the valley floor width to valley height v four episodes of alluvial fan terraces were upstream from the range bounding fault which formation ages were estimated as 116 64 35 and 10 ka bp according to optically stimulated luminescence osl dating combined with previous 14 c and osl ages the correlation between time of the terraces formation and climatic fluctuations recorded in a guliya ice core reveals that alluvial fan aggradation was concentrated during the cold stages and that incision occurred during the succeeding cold to warm transitions a majority of alluvial fan terraces developed in accelerated uplift since 64 ka which indicates that tectonic uplift provided the driving force for continuous downcutting after climatic change triggered it geomorphic indices channel gradient and v distribution reconstructs the model of discrepant uplift in the langshan range with the fastest uplift rate in the central part which is controlled by range bounding faults

pleistocene fluvial terraces from northern france seine yonne somme synthesis and new results from interglacial deposits the seine yonne and somme are the main rivers draining northwestern france and flowing into the channel during pleistocene cold stages they were tributaries of the fleuve manche they are characterised by well developed stepped terrace systems showing up to 10 incision steps for the last 1 ma after 15 years of research and the synthesis of stratigraphical sedimentological bioclimatical data and numerical dating these terrace systems are interpreted as the response of the fluvial environments to climatic cyclicity superimposed on a background of slow tectonic uplift the comparison of these three terrace systems shows that the incision budget is similar within the studied area about 55 65 m 1 ma implying relative homogeneity of uplift in the main part of the area beyond marine influence the analysis of each stepped alluvial formation shows regular sediment balance generally composed of coarse periglacial gravels pleniglacial covered by fine grained sediments locally overlain by calcareous tufa interglacial however in the lower seine valley close to the present coast the low terrace includes two estuarine interglacial units interbedded within periglacial gravel units nevertheless until recently evidence of full interglacial conditions remained elusive in fluvial contexts especially in the somme to address these issues a new research programme has been launched on tufa deposits that are the best candidate to register the climatic optimum initial results from la celle seine saint acheul and caours somme allow palaeoenvironmental reconstructions of mis 11 and 5e and thus confirm the importance of calcareous tufa to define a reference record of pleistocene interglacials for northern france moreover it has been previously demonstrated that the main incision leading to terrace formation can be attributed to the transition between interglacial and glacial during early glacial phases the new results from interglacial records have important implications concerning the precise occurrence of the major incision phases within the climatic cycle as they provide the starting point immediately preceding downcutting

luminescence dating of the niederweningen mammoth site switzerland abstract luminescence dating is used to further constrain the so far controversial age of the mammoth site at niederweningen switzerland gamma spectrometric analyses reveal the presence of radioactive disequilibria in the uranium decay chain in most of the samples but these cause only minor uncertainties in the age estimates the major uncertainty is actually related to the problem of estimating the average water content for the whole burial time nevertheless even considering these problems involved with dose rate determination the dating results clearly indicate that the peat is significantly younger than early wurmian in contrast to some previous assumptions together with the results of radiocarbon dating and pollen analyses the luminescence ages point to a correlation of the mammoth peat with interstadial conditions during the early part of the middle wurmian at around 45 ka ago

plio pleistocene transpressional reactivation of paleozoic and paleogene structures in the rhine bresse transform zone northern switzerland and eastern france pliocene to recent uplift and shortening in the southern rhinegraben is documented by deformation of pliocene fluvial gravels deposited on a nearly planar surface as well as by progressive deflection and capture of rivers this deformation is suggested to result from thick skinned tectonic movements as evidenced by ob servations on seismic records which demonstrate a spatial coincidence between en chelon anticlines at the surface and faults located in the crystalline basement these findings contradict the often invoked thin skinned tectonism in the recent tectonic history of the rhine graben in particular the transfer zone between the rhinegraben and the bressegraben is very suitable for reactivation under the present day stress field thick skinned reactivation of faults in the basement is also expressed by focal plane mechanisms of recent earth quakes showing strike slip rather than reverse faulting characteristics this is of importance for the densely populated and industrialised southern rhinegraben pre viously affected by large earthquakes in historical times e g basel 1356

eocene oligocene tectonics and kinematics of the rhine saone continental transform zone eastern france a tectonic analysis of brittle deformaton was performed in the rhine saone transform in order to decipher and understand the deformation processes in a typical continental hansfer zone cenozoic major and minor fault patterns are described and brittle structures are interpreted in terms of paleostress orientations the eocene n s compression related to africa eurasia convergence is marked mainly by strike slip faults it was followed by a major phase of crustal extension mainly oligocene in age related to the west european rifting this extensional phase is expressed by normal faults tension gashes and extensional strike slip faults which are especially abundant in the transform zone these two events are found to be quite different in terms of distribution of horizontal shess trajectories the trend of ol axes is very homogeneous for the n s compression whereas o3 orientations associated with the major extension vary from e w in most of the rift system to i v se within the transform zone finally the mio pliocene tectonic emplacement of the jura fold and thrust belt is marked in the field by strike slip faults associated with a well defined trend of ol oriented w iiw e se to nw se the preexisting basement fracture pattern between the grabens was also considered in order to estimate which faults were likely to have been reactivated during the oligocene transform kinematics and the theoretical shear motion on these inherited fault surfaces when submitted to e w extension was calculated left laterauextensional reactivation of a preexisting 60 n trending fault system in the brittle upper crust is likely to have accommodated the shear strain arising between the rift segments in response to crustal stretching two independent numerical modelings based on distinct element and finite element analyses respectively enabled us to verify and to refine the hypothesis of transform kinematics related to e w extension and inducing regional perturbations of extensional stress trajectories the overall mechanism and the transtensional kinematics of the rhine saone transform zone are thus tightly conshained the inherited crustal anisotropy the large scale perturbations of extensional stress trajectories and the development of distributed brittle deformation within the sedimentary cover are found to play a major role in the tectonic evolution of continental rift transform systems

slow slip slow earthquakes period two cycles full and partial ruptures and deterministic chaos in a single asperity fault abstract the assimilation of geological geophysical and laboratory data in physics based models of fault dynamics promises increasingly realistic simulations of the seismic cycle to assist this effort i explore the dynamics of a single velocity weakening asperity to delineate the relationship between a fault physical properties and the style of faulting during the seismic cycle based on a micro physical model of rate and state friction from a dimensional analysis four non dimensional parameters control the characteristics of slip events and the behavior during the interseismic period including the dieterich ruina rice number ru which is proportional to the ratio of asperity to critical nucleation size w h and rb b a b where a and b control the direct and local evolutionary effects respectively for sufficiently large rb the ru number controls the spectrum of fault slip from periodic slow slip events to aperiodic fast ruptures in finite faults but not in semi infinite faults the transition between these end members includes a bifurcation that involves period two period four period six cycles and deterministic chaos with increasing ru macroscopic fault slip is stabilized as rb vanishes even as ru 1 for finite faults but not for semi infinite faults the transition between slow and fast ruptures for increasing rb includes another type of bifurcation with period two and period four cycles of slow and fast ruptures for 0

age spreading rates and spreading asymmetry of the world s ocean crust we present four companion digital models of the age age uncertainty spreading rates and spreading asymmetries of the world s ocean basins as geographic and mercator grids with 2 arc min resolution the grids include data from all the major ocean basins as well as detailed reconstructions of back arc basins the age spreading rate and asymmetry at each grid node are determined by linear interpolation between adjacent seafloor isochrons in the direction of spreading ages for ocean floor between the oldest identified magnetic anomalies and continental crust are interpolated by geological estimates of the ages of passive continental margin segments the age uncertainties for grid cells coinciding with marine magnetic anomaly identifications observed or rotated to their conjugate ridge flanks are based on the difference between gridded age and observed age the uncertainties are also a function of the distance of a given grid cell to the nearest age observation and the proximity to fracture zones or other age discontinuities asymmetries in crustal accretion appear to be frequently related to asthenospheric flow from mantle plumes to spreading ridges resulting in ridge jumps toward hot spots we also use the new age grid to compute global residual basement depth grids from the difference between observed oceanic basement depth and predicted depth using three alternative age depth relationships the new set of grids helps to investigate prominent negative depth anomalies which may be alternatively related to subducted slab material descending in the mantle or to asthenospheric flow a combination of our digital grids and the associated relative and absolute plate motion model with seismic tomography and mantle convection model outputs represents a valuable set of tools to investigate geodynamic problems

postseismic deformation following the 1999 chi chi earthquake taiwan implication for lower crust rheology on 1999 september 21 the mw 7 6 chi chi earthquake ruptured a segment of the chelungpu fault a frontal thrust fault of the western foothills of taiwan the stress perturbation induced by the rupture triggered a transient deformation across the island which was well recorded by a wide network of continuously operating gps stations the analysis of more than ten years of these data reveals a heterogeneous pattern of postseismic displacements with relaxation times varying by a factor of more than ten and large cumulative displacements at great distances in particular along the longitudinal valley in eastern taiwan where relaxation times are also longer we show that while afterslip is the dominant relaxation process in the epicentral area viscoelastic relaxation is needed to explain the pattern and time evolution of displacements at the larger scale we model the spatiotemporal behavior of the transient deformation as the result of afterslip on the decollement that extends downdip of the chelungpu thrust and viscoelastic flow in the lower crust and in the mid crust below the central range we construct a model of deformation driven by coseismic stress change where afterslip and viscoelastic flow are fully coupled the model is compatible with the shorter relaxation times observed in the near field which are due to continued fault slip and the longer characteristic relaxation times and the reversed polarity of vertical displacements observed east of the central range our preferred model shows a viscosity of 0 5 1 x 10 19 pa s at lower crustal depths and 5 x 10 17 pa s in the mid crust below the central range between 10 and 30 km depth the low viscosity zone at mid crustal depth below the central range coincides with a region of low seismicity where rapid advection of heat due to surface erosion coupled with underplating maintain high temperatures estimated to be between 300 c and 600 c from the modeling of thermo chronology and surface heat flow data

pleistocene tectonics inferred from fluvial terraces of the northern upper rhine graben germany abstract this study of fluvial terraces of the river rhine and tributaries aims to search for indications of pleistocene tectonic activity the study area includes the northern upper rhine graben urg the mainz basin and the adjacent rhenish massif with the middle rhine valley high rates of quaternary surface processes large amount of human modifications relatively slow tectonic deformation and presently low intra plate seismic activity characterize this area therefore the records of relatively slow tectonic deformation are less well preserved and thus difficult to detect this study uses the relative position of fluvial terraces to determine the more local effects of fault movements on the terraces and to evaluate their displacement rates and patterns the research is based on a review of previous terrace studies and new terrace mapping from the eastern mainz basin and the bordering urg using topographic map interpretations and field observations this newly mapped sequence of terrace surfaces can be correlated to other terraces in the vicinity on the basis of relative height levels terrace correlation between the western mainz basin and middle rhine valley relies on a single chronostratigraphic unit mosbach sands and additional relative height correlations this is the first study to present a continuous correlation of terraces from the western margin of the urg to the rhenish massif and enables the study of the transition from the subsiding graben to the uplifted rhenish massif by means of a longitudinal profile which ranges from the urg to the rhenish massif the influence of individual fault movements on the terrace levels and the large scale regional uplift is demonstrated it is evident from the profile that the uplift of early to middle pleistocene terraces increases northwards towards the rhenish massif the uplift was diachronic with a significant pulse occurring first in the northern urg lower pleistocene and later in the rhenish massif middle pleistocene the largest vertical displacements are recorded for the boundary fault separating the mainz basin and the rhenish massif hunsruck taunus boundary fault and for faults bounding the northeastern mainz basin the motions and displacement rates calculated for individual faults indicate deformation rates in the order of 0 01 0 08 mm year at this stage the calculation of displacement rates depends mostly on a single dated stratigraphic unit additional dating of terrace deposits is urgently needed to better constrain the temporal development of the terrace sequence and the impact of tectonic movements

a unified gps based earthquake catalog for the sumatran plate boundary between 2002 and 2013 we have compiled the first self consistent gps based earthquake catalog for the sumatran plate boundary using continuous daily position time series from the sumatran gps array sugar we document 30 earthquakes which occurred within or outside the sugar network from august 2002 through the end of 2013 and we provide estimates of both vertical and horizontal coseismic offsets associated with 1 m9 2 3 m8 6 m7 19 m6 and 1 m5 9 earthquakes as well as postseismic decay amplitudes and times associated with 9 m 7 earthquakes and 1 m6 7 earthquake for most of the previously studied earthquakes our geodetic catalog provides more complete coseismic displacements than those published showing consistent patterns of motion across a large range of distances for many of the moderate to large earthquakes we publish their coseismic displacements for the first time providing new constraints on their locations and slip distributions for the postseismic time series we have tackled the challenge of separating the signals for individual events from the overlapping effects of many other earthquakes as a result we have obtained either new or much longer time series than previously published based on our long time series we find logarithmic decay times ranging from several days to more than 20 years and sometimes a second decay time is needed suggesting that when studying large to great sumatran earthquakes we need to consider multiple postseismic mechanisms our geodetic catalog provides rich spatial and temporal sumatran earthquake cycle information for future studies of the physics and dynamics of the sumatran plate boundary

alluvial river response to neotectonic deformation in louisiana and mississippi repeat geodetic surveys show uplift of the monroe and wiggins anticlines in louisiana and mississippi there are deformed quaternary terraces which indicate long term deformation in the valleys of the alluvial rivers that cross these structures and there are floodplain and channel convexities that provide evidence of modern deformation in addition the channels show significant variations of morphology sinuosity gradient and depth and behavior appropriate to reaches of increased and decreased valley slope these alluvial rivers are adjusting to modern deformation and their adjustment confirms two geodetic leveling anomalies

coulomb stress perturbation after great earthquakes in the sumatran subduction zone potential impacts in the surrounding region abstract the sumatran subduction zone has been seismically very active compared with other major subduction zones in the world since 2004 a sequence of large earthquakes ruptured along the trench including the 2004 mw 9 2 sumatra andaman the 2005 mw 8 6 nias simeulue the 2007 mw 8 4 bengkulu the 2010 mw 7 8 mentawai tsunami earthquakes and numerous moderate and small events these earthquakes released stress over tens of seconds to minutes disturbing the lithosphere and asthenosphere across a broad region as earthquake introduced stress disturbance can trigger tremendous aftershocks and sometimes precipitate large earthquakes in their vicinity gaining a detailed picture of spatial and temporal stress evolution on the fault and its neighboring faults is crucial for seismic forecasting here we have developed spatiotemporal coulomb stress models for the sumatran region which includes the sumatran subduction zone and the sumatran fault using a well studied postseismic model this postseismic model is constrained by decade long time series of geodetic observations from the sumatran gps array sugar and from tide gauge data in southeast asia we show that coulomb stress changes imparted by co and post seismic processes of previous great ruptures could well explain the temporal and spatial connection between seismicity and stress evolution most importantly our results reveal that the stress in the mentawai seismic gap of the sumatran subduction zone was loaded by more than two bars these stress perturbations could potentially trigger the rupture of the mentawai seismic gap which was already overdue in the last seismic cycle now the likelihood for the failure of this gap is even higher than before 2004 we also find that along the sumatran fault stress has increased to more than one bar which may explain the surrounding seismicity consequently we highlight the considerable seismic hazard and associated tsunami threat to the neighboring regions

modeling the 2012 wharton basin earthquakes off sumatra complete lithospheric failure a sequence of large strike slip earthquakes occurred west of sunda trench beneath the wharton basin first reports indicate that the main shock was extremely complex involving three to four subevents m w 8 with a maze of aftershocks we investigate slip models of the two largest earthquakes by joint inversion of regional and teleseismic waveform data using the m w 7 2 foreshock we developed hybrid green s functions for the regional stations to approximate the mixture of oceanic and continental paths the main shock fault geometry is defined based on the back projection results point source mechanisms aftershock distribution and fine tune of grid searches the fault system contains three faults labeled f1 89 289 for dip strike f2 74 20 and f3 60 310 the inversion indicates that the main rupture consisted of a cascade of high stress drop asperities up to 30 mpa extending as deep as 50 km the rupture propagated smoothly from one fault to the next f1 f2 and f3 in sequence with rupture velocities of 2 0 2 5 km s the whole process lasted about 200 s and the major moment release 70 took place on the n s oriented f2 the m w 8 2 aftershock happened about 2 h later on a n s oriented fault with a relatively short duration 60 s and also ruptured as deep as 50 km the slip distributions suggest that the earthquake sequence was part of a broad left lateral shear zone between the australian and indian plates and ruptured the whole lithosphere these earthquakes apparently reactivated existing fracture zones and were probably triggered by unclamping of the great sumatran earthquake of 2004

european cenozoic rift system abstract the european cenozoic rift system extends from the coast of the north sea to the mediterranean over a distance of some 1100 km it finds its southern prolongation in the valencia trough and a plio pleistocene volcanic chain crossing the atlas ranges development of this mega rift was paralleled by orogenic activity in the alps and pyrenees major rift domes accompanied by subsidence reversal of their axial grabens developed 20 40 ma after beginning of rifting uplift of the rhenish shield is related to progressive thermal lithospheric thinning the vosges black forest and the massif central domes are probably underlain by asthenoliths emplaced at the crust mantle boundary evolution of this rift system is thought to be governed by the interaction of the eurasian and african plates and by early phases of a plate boundary reorganization that may lead to the break up of the present continent assembly

yellow river terrace sequences of the gonghe guide section in the northeastern qinghai tibet implications for plateau uplift abstract the uplift of the tibetan plateau was a significant event in terms of global landforms and climate but the exact nature of the uplift process remains contested among geologists in the uplifted inland area of the plateau river terrace formation has been controlled mainly by tectonic uplift which means that analyses of river terraces are an excellent means of investigating the uplift process in this paper we establish the terrace sequence of the yellow river in the gonghe guide section of the northeastern tibetan plateau making use of field investigations gravel analysis and electron spin resonance esr dating terraces t3 t9 of the numbered sequence formed at 0 13 0 18 0 23 0 41 0 85 0 93 and 1 32 ma moving backwards in time and upwards from the valley floor whereas terraces t11 t20 formed at 1 71 1 75 1 88 1 94 2 01 2 12 2 23 2 31 2 36 and 2 47 ma this suggests that the yellow river existed in gonghe and guide basins for at least the last 2 47 ma the incision rates of the yellow river in the gonghe guide section indicate that there were three distinct phases of uplift of the northeastern tibetan plateau occurring at different rates with an average uplift rate of 0 26 mm yr during the quaternary these results support the multi stage uplift model which states that the tibetan plateau has experienced continuous uplift since 8 ma but contradicts both the early uplift theory which holds that the uplift of the tibetan plateau occurred mainly before the pliocene and the notion of a late and rapid uplift of the plateau that began at 3 6 ma

deformation cycles of subduction earthquakes in a viscoelastic earth subduction zones produce the largest earthquakes over the past two decades space geodesy has revolutionized our view of crustal deformation between consecutive earthquakes the short time span of modern measurements necessitates comparative studies of subduction zones that are at different stages of the deformation cycle piecing together geodetic snapshots from different subduction zones leads to a unifying picture in which the deformation is controlled by both the short term years and long term decades and centuries viscous behaviour of the mantle traditional views based on elastic models such as coseismic deformation being a mirror image of interseismic deformation are being thoroughly revised snapshots of subduction zones using space geodesy reveal that the viscous behaviour of the mantle controls crustal deformation requiring the revision of traditional elastic models for earthquake risk assessment space geodesy the use of satellites to monitor earth has revolutionized our view of crustal deformation between consecutive earthquakes however the brevity of such measurements means that studies must be done by comparing multiple subduction zones at different stages of the earthquake cycle by piecing together geodetic snapshots from the sumatra chile and cascadia subduction zones this review presents a unifying picture in which deformation is controlled by the viscous behaviour of the mantle in both the short term years and the long term decades to centuries

slab1 0 a three dimensional model of global subduction zone geometries 1 we describe and present a new model of global subduction zone geometries called slab1 0 an extension of previous efforts to constrain the two dimensional non planar geometry of subduction zones around the focus of large earthquakes slab1 0 describes the detailed non planar three dimensional geometry of approximately 85 of subduction zones worldwide while the model focuses on the detailed form of each slab from their trenches through the seismogenic zone where it combines data sets from active source and passive seismology it also continues to the limits of their seismic extent in the upper mid mantle providing a uniform approach to the definition of the entire seismically active slab geometry examples are shown for two well constrained global locations models for many other regions are available and can be freely downloaded in several formats from our new slab1 0 website http on doi gov d9arbs we describe improvements in our two dimensional geometry constraint inversion including the use of average active source seismic data profiles in the shallow trench regions where data are otherwise lacking derived from the interpolation between other active source seismic data along strike in the same subduction zone we include several analyses of the uncertainty and robustness of our three dimensional interpolation methods in addition we use the filtered subduction related earthquake data sets compiled to build slab1 0 in a reassessment of previous analyses of the deep limit of the thrust interface seismogenic zone for all subduction zones included in our global model thus far concluding that the width of these seismogenic zones is on average 30 larger than previous studies have suggested

the somme valley terrace system northern france a model of river response to quaternary climatic variations since 800 000 bp recent research on the somme valley terrace deposits that began in 1987 has resulted in an integrated sequence of geological and geomorphological evidence for this area that is of particular significance for prehistoric investigations this has been achieved using previous evidence and new results from archaeological and geological excavations these include longitudinal profiles cartography and detailed synthesis of sections of alluvial deposits stratigraphy of river deposits and overlying loess sequences the work based on a study of the geometry of the terrace system has resulted in the identification of ninestepped alluvial formations that occur along 70 km of the valley detailed study permits the integration of the various alluvial sequences this suggests that each alluvial sequence results from sedimentation through a single glacial interglacial climatic cycle this hypothesis is confirmed by investigation of soil and loess sequences of the deposits overlying the fluvial sediments the synthesis presented provides a basis for understanding the deposition of the terrace system and an initial chronostratigraphic interpretation for the deposits

april 2012 intra oceanic seismicity off sumatra boosted by the banda aceh megathrust the two earthquakes of respective magnitudes 8 6 and 8 2 that occurred off the coast of the sumatra subduction zone on 11 april 2012 are shown to be part of a continuing boost of the intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes on 11 april 2012 two of the largest strike slip earthquakes ever recorded at magnitudes of 8 7 and 8 2 occurred in the northeastern indian ocean a few hundred kilometres off the coast of sumatra three groups now report the analysis of seismic data from the days and months before and after these events as well as the events themselves matthias delescluse and co authors show that these earthquakes are part of the ongoing boost of intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes they conclude that the australian plate driven by slab pull forces at the sunda trench is gradually detaching from the indian plate han yue and colleagues show that the 11 april event involved a complex four fault rupture lasting several minutes followed two hours later by a magnitude 8 2 aftershock these great ruptures on a lattice of strike slip faults that extends through the crust and into the upper mantle represent large lithospheric deformation that may eventually create a localized boundary between the indian and australian plates fred pollitz and colleagues show that in the six days following 11 april the global rate of remote earthquakes with magnitudes greater than 5 5 increased nearly fivefold and events up to magnitude 7 seem to have been triggered the unprecedented delayed triggering power of this earthquake may arise from its strike slip source geometry or because it struck at a time of an unusually low global earthquake rate and increased the number of nucleation sites that were very close to failure large earthquakes nucleate at tectonic plate boundaries and their occurrence within a plate s interior remains rare and poorly documented especially offshore the two large earthquakes that struck the northeastern indian ocean on 11 april 2012 are an exception they are the largest strike slip events reported in historical times1 2 and triggered large aftershocks worldwide3 yet they occurred within an intra oceanic setting along the fossil fabric of the extinct wharton basin rather than on a discrete plate boundary4 5 6 7 8 here we show that the 11 april 2012 twin earthquakes are part of a continuing boost of the intraplate deformation between india and australia that followed the aceh 2004 and nias 2005 megathrust earthquakes subsequent to a stress transfer process recognized at other subduction zones9 10 using coulomb stress change calculations we show that the coseismic slips of the aceh and nias earthquakes can promote oceanic left lateral strike slip earthquakes on pre existing meridian aligned fault planes we further show that persistent viscous relaxation in the asthenospheric mantle several years after the aceh megathrust explains the time lag between the 2004 megathrust and the 2012 intraplate events on a short timescale the 2012 events provide new evidence for the interplay between megathrusts at the subduction interface and intraplate deformation offshore on a longer geological timescale the australian plate driven by slab pull forces at the sunda trench is detaching from the indian plate which is subjected to resisting forces at the himalayan front6 8 11

constraints on mantle viscosity structure from continental drift histories in spherical mantle convection models abstract earth s continents drift in response to the force balance between mantle flow and plate tectonics and actively change the plate mantle coupling thus the patterns of continental drift provide relevant information on the coupled evolution of surface tectonics mantle structure and dynamics here we investigate rheological controls on such evolutions and use surface tectonic patterns to derive inferences on mantle viscosity structure on earth we employ global spherical models of mantle convection featuring self consistently generated plate tectonics which are used to compute time evolving continental configurations for different mantle and lithosphere structures our results highlight the importance of the wavelength of mantle flow for continental configuration evolution too strong short wavelength components complicate the aggregation of large continental clusters while too stable very long wavelength flow tends to enforce compact supercontinent clustering without reasonable dispersal frequencies earth like continental drift with episodic collisions and dispersals thus requires a viscosity structure that supports long wavelength flow but also allows for shorter wavelength contributions such a criterion alone is a rather permissive constraint on internal structure but it can be improved by considering continental oceanic plate speed ratios and the toroidal poloidal partitioning of plate motions the best approximation of earth s recent tectonic evolution is then achieved with an intermediate lithospheric yield stress and a viscosity structure in which oceanic plates are 103 more viscous than the characteristic upper mantle which itself is 100 200 less viscous than the lowermost mantle such a structure causes continents to move on average 2 2 1 0 slower than oceanic plates consistent with estimates from present day and from plate reconstructions this does not require a low viscosity asthenosphere globally extending below continental roots however this plate speed ratio may undergo strong fluctuations on timescales of several 100 myr that may be linked to periods of enhanced continental collisions and are not yet captured by current tectonic reconstructions

modeling seismic cycles of great megathrust earthquakes across the scales with focus at postseismic phase subduction is substantially multi scale process where the stresses are built by long term tectonic motions modified by sudden jerky deformations during earthquakes and then restored by following multiple relaxation processes here we develop a cross scale thermomechanical model aimed to simulate the subduction process from 1 minute to million years time scale the model employs elasticity nonlinear transient viscous rheology and rate and state friction it generates spontaneous earthquake sequences and by using an adaptive time step algorithm recreates the deformation process as observed naturally during the seismic cycle and multiple seismic cycles the model predicts that viscosity in the mantle wedge drops by more than three orders of magnitude during the great earthquake with a magnitude above 9 as a result the surface velocities just an hour or day after the earthquake are controlled by viscoelastic relaxation in the several hundred km of mantle landward of the trench and not by the afterslip localized at the fault as is currently believed our model replicates centuries long seismic cycles exhibited by the greatest earthquakes and is consistent with the postseismic surface displacements recorded after the great tohoku earthquake we demonstrate that there is no contradiction between extremely low mechanical coupling at the subduction megathrust in south chile inferred from long term geodynamic models and appearance of the largest earthquakes like the great chile 1960 earthquake

stream terrace genesis implications for soil development genesis of three distinct types of stream terraces can be understood through application of the concepts of tectonically induced downcutting base level of erosion complex response threshold of critical power diachronous and synchronous response times and static and dynamic equilibrium climatic and tectonic stream terraces are major terraces below which flights of minor complex response degradation terraces can form these three types of terraces can be summarized by describing a downcutting aggradation renewed downcutting sequence for streams with gravell bedload by tectonically induced downcutting streams degrade to achieve and maintain a dynamic equilibrium longitudinal profile at the base level of erosion lateral erosion bevels bedrock beneath active channels to create major straths that are the fundamental tectonic stream terrace landform aggradation events record brief reversals of long term tectonically induced downcutting because they raise active channels they may be considered as major the result of climatic perturbations or minor the result of complex response model types of perturbations climatically controlled aggradation followed by degradation leaves an aggradation surface this type of fill terrace tread is the fundamental climatic stream terrace landform aggradation surfaces may be buried by subsequent episodes of deposition unless intervening tectonically induced downcutting is sufficient for younger aggradation surfaces to form below older surfaces raising of the active channel by either tectonic uplift or by climatically induced aggradation provides the vertical space for degradation terraces to form first in alluvial fill and then in underlying bedrock along tectonically active streams these are complex response terraces because they result from interactions of dependent variables within a given fluvial system pauses in degradation to a new base level of erosion and or minor episodes of backfilling lead to formation of complex response fill cut and strath or of fill terraces fill cut terraces are formed in alluvium they are complex response terraces because they are higher than the base level of erosion good exposures and dating are needed to distinguish static equilibrium complex response minor strath terraces from dynamic equilibrium tectonic major straths strath terraces may be regarded as complex response terraces where degradation rates between times terrace tread formation exceed the long term uplift rate for the reach based on ages and positions of tectonic terraces late quaternary global climatic changes control aggradation events and even the times of cutting of major tectonic straths because the base level of erosion can not be attained during times of climatically driven aggradation degradation events most terrace soils form on treads of climatic and complex response terraces aggradation surfaces may provide an ideal flight of terraces on which to study a soils chronosequence each aggradation event is recorded by a single relict soil where tectonically induced downcutting is sufficient to provide clear altitudinal separation of the terrace treads multiple paleosols are typical of tectonically stable regions where younger aggradation events spread alluvium over treads of older climatic terraces pedons on a climatic terrace in a small fluvial system commonly are roughly synchronous variations of soil properties that can be attributed to temporal differences will be minor compared to altitudinally controlled climatic factors climatic terraces of adjacent watersheds also should be roughly synchronous correlatable variations of soil properties that can be attributed to temporal differences will be minor compared to lithologic and climatic factors between different watersheds such generalizations may not apply to basins with sufficient relief that geomorphic responses to climatic changes occur at different and overlapping times and to large rivers whose widely separated reaches are characterized by different response times to climatic perturbations soils on climatic terraces of distant watershedswill not be synchronous if their respective aggradation events occur during full glacial times and interglacial times soils on some complex response terraces may be diachronous within a given fluvial system and typically are diachronous between watersheds

high temperature transient creep in olivine rocks abstract the transient creep behaviour of two natural dunites has been investigated at temperatures between 1373 and 1573 k and a confining pressure of 300 mpa in a high resolution gas medium deformation apparatus the specimens were deformed in constant stress experiments in the presence of an aqueous phase and were oriented perpendicular to foliation the results confirm the finding of earlier workers that the high temperature transient flow properties of olivine rocks can be effectively modelled in terms of a burgers body rheology observations of time dependent strain recovery after unloading further support this model the viscosity in the transient regime 1 is found to have the same sensitivity to temperature and stress within the errors of each estimate as has been found previously for steady state creep viscosity 2 thus the ratio 2 1 is found to be relatively insensitive to temperature and stress with values between 0 17 and 0 67 these values are higher than the 2 1 0 1 that has generally been assumed in geophysical modelling of upper mantle transient deformation but are similar to the results of previous experiments with olivine single crystals the ratio of the shear moduli in the transient and steady state regimes 2 1 is found to be weakly sensitive to temperature at 250 mpa stress and 300 mpa confining pressure the value of 2 1 decreases slowly as temperature increases for the present experiments 0 05 2 1 which is comparable to the range of values reported in previous studies

interactions between thin and thick skinned tectonics at the northwestern front of the jura fold and thrust belt eastern france 1 this study investigates spatial and temporal interactions of thin and thick skinned tectonics in a classical foreland setting located at the front of the jura fold and thrust belt in eastern france the working area coincides with the intracontinental rhine bresse transfer zone and represents the most external front of the deformed alpine foreland the investigation combines analyses of largely unpublished and newly available subsurface information with our own structural data including an exhaustive paleostress analysis and geomorphologic observations results are provided in the form of a new tectonic map and a series of regional cross sections through the study area the besancon zone forming the most external part of the thin skinned fold and thrust belt encroached onto the eo oligocene rhine bresse transfer fault system until early pliocene times thrust propagation was largely controlled by the late paleozoic to paleogene preexisting fault pattern that characterizes the rhine bresse transfer zone thick skinned deformation dominant throughout the avant monts zone located farther to the west was associated with compressional to transpressional reactivation of such faults overprinting and crosscutting criteria of fault slip data allow distinguishing between systematically fanning maximum horizontal stress axes that define the front of the thin skinned jura fold and thrust belt and consistently nw se directed maximum horizontal stress axes that characterize deformation of the autochthonous cover of the foreland which is affected by thick skinned tectonics tectonic and geomorphic analyses indicate that thick skinned tectonics started at a very late stage of foreland deformation post early pliocene geomorphic observations imply that deformation between mesozoic cover and basement is locally still decoupled however overprinting relationships and recent seismicity suggest that present day tectonic activity is thick skinned which probably reflects ongoing tectonic underplating in the alpine foreland

climatically controlled terraces in uplifting mountain areas abstract terraces in tectonically active mountains and uplands record both tectonic uplift and rhythmic climatic variations the author discusses the question of how to distinguish the role of both tectonic and climatic factors in central europe with quaternary uplift of the order of 50 100 m climatically controlled terraces are well developed cold stage aggradation is recognised through the interfingering of periglacial alluvial slope and loess deposits erosional activity prevailed in transitional periods then follows a discussion of difficulties connected with the construction of timing and rate of tectonic uplift based on the depth of incision in the bedrock and on facies differentiation the examination of changes in longitudinal profiles of river valleys indicates that unrejuvenated upper valley courses cannot be used for the reconstruction of tectonic uplift finally the author presents several types of adaptation of tectonically determined downcutting and aggradation to quaternary climatic cyclicity

climatic and tectonic controls on the development of the river ognon terrace system eastern france the river ognon in eastern france is the principal drainage of the southwestern vosges mountains its lowermost valley reach is oriented parallel to the northwestern front of the alpine collision zone and is characterized by a well developed terrace system geomorphological sedimentological and geochronological analyses were performed on this terrace system and associated deposits the results allow for reconstructing the pleistocene evolution of the river valley and for concluding on the processes that led to the formation of the terrace system the lithological characterization of the terrace deposits by means of heavy mineral analyses indicates pronounced modifications of the river s drainage area optically stimulated luminescence dating suggests that the last significant catchment modification and associated sediment accumulation correlates with the last glacial advance in the vosges mountains despite the apparently strong impact of climatic processes on the evolution of the river ognon our investigation also indicates a mild tectonic influence on presently observed terrace distribution

postseismic deformation due to the mw 6 0 2004 parkfield earthquake stress driven creep on a fault with spatially variable rate and state friction parameters 1 we investigate the coseismic and postseismic deformation due to the m w 6 0 2004 parkfield california earthquake we produce coseismic and postseismic slip models by inverting data from an array of 14 continuous gps stations from the scign network kinematic inversions of postseismic gps data over a time period of 3 years show that afterslip occurred in areas of low seismicity and low coseismic slip predominantly at a depth of 5 km inversions suggest that coseismic stress increases were relaxed by predominantly aseismic afterslip on a fault plane the kinetics of afterslip is consistent with a velocity strengthening friction generalized to include the case of infinitesimal velocities we performed simulations of stress driven creep using a numerical model that evaluates the time dependent deformation due to coseismic stress changes in a viscoelastoplastic half space starting with a coseismic slip distribution we compute the time dependent evolution of afterslip on a fault plane and the associated displacements at the gps stations data are best explained by a rate strengthening model with frictional parameter a b 7 x 10 3 at a high end of values observed in laboratory experiments we also find that the geodetic moment due to creep is a factor of 100 greater than the cumulative seismic moment of aftershocks the rate of aftershocks in the top 10 km of the seismogenic zone mirrors the kinetics of afterslip suggesting that postearthquake seismicity is governed by loading from the nearby aseismic creep the san andreas fault around parkfield is deduced to have large along strike variations in rate and state frictional properties velocity strengthening areas may be responsible for the separation of the coseismic slip in two distinct asperities and for the ongoing aseismic creep occurring between the velocity weakening patches after the 2004 rupture

present day and future tectonic underplating in the western swiss alps reconciliation of basement wrench faulting and decollement folding of the jura and molasse basin in the alpine foreland abstract the western alps form a geodynamically active mountain belt showing the typical features of an evolving orogenic wedge with its pro wedge geometry to the nnw and its retro wedge structures to the sse renewed tectonic underplating of european continental crust occurred after the orogenic wedge underwent major dynamic disequilibrium following the break off of the southward subducting slab of the european passive margin the most important of these basement imbricates are the mont blanc aiguilles rouges and gastern aar crystalline massifs also forming the alps highest mountains the upper plate present day orogenic wedge of the western alps includes the molasse basin and the jura fold and thrust belt both decoupled from the basement over a basal decollement surface the overall geometry of this wedge appears to be strongly unstable according to simple wedge models in its attempt to regain stability out of sequence thrusts form in the existing basement nappes but also new basement nappes should develop beneath the southern portion of the molasse basin new out of sequence thrusts in the cover trigger higher than average uplift rates concentrated around the newly forming structures and are accompanied by a concentration of earthquakes tectonic underplating is further corroborated by neotectonics and the tectonic structures observed in the prealpes molasse basin and jura similarly uplift rates and earthquakes along the southern edge of the jura mountains seem to witness the development of a new incipient basement nappe at depth partial inversion of former permo carboniferous grabens in the basement a possible spatial coincidence of areas with strong earthquake activity and zones with uplift rates above surrounding values suggest a common mechanism for their origin in the western swiss alpine foreland combined with information from basement geometry and wedge dynamics it is proposed that the common mechanism is the development of basement imbricates by tectonic underplating the proposed model for ongoing and possible future tectonic underplating beneath an active alpine orogenic wedge also allows to reconcile the models of basement wrench faulting in the molasse basin and jura with the distant push theory where the molasse basin and jura develop over a basal decollement horizon

evidence for postseismic deformation of the lower crust following the 2004 mw6 0 parkfield earthquake previous studies have shown that postseismic relaxation following the 2004 mw6 0 parkfield ca earthquake is dominated by afterslip however we show that some fraction of the afterslip inferred from kinematic inversion to have occurred immediately below the seismically ruptured area may in fact be a substitute for viscous postseismic deformation of the lower crust using continuous gps and synthetic aperture radar interferometry we estimate the relative contribution of shallow afterslip at depth less than 20km and deeper seated deformation required to account for observed postseismic surface displacements exploiting the possible separation in space and time of the time series of displacements predicted from viscoelastic relaxation we devise a linear inversion scheme that allows inverting jointly for the contribution of afterslip and viscoelastic flow as a function of time we find that a wide range of models involving variable amounts of viscoelastic deformation can fit the observations equally well provided that they allow some fraction of deep seated deformation at depth larger than 20 km these models require that the moment released by postseismic relaxation over 5 years following the earthquake reached nearly as much as 200 of the coseismic moment all the models show a remarkable complementarity of coseismic and shallow afterslip distributions some significant deformation at lower crustal depth 20 26 km is required to fit the geodetic data the condition that postseismic deformation cannot exceed complete relaxation places a constraint on the amount of deep seated deformation the analysis requires an effective viscosity of at least 10 18 pa s of the lower crust assuming a semi infinite homogeneous viscous domain this deep seated deformation is consistent with the depth range of tremors which also show a transient postseismic response and could explain as much as 50 of the total postseismic geodetic moment the remaining fraction being due to afterslip at depth shallower than 20 km lower crustal postseismic deformation could reflect a combination of localized ductile deformation and aseismic frictional sliding