slip rate measurements on the karakorum fault may imply secular variations in fault motion beryllium 10 surface exposure dating of offset moraines on one branch of the karakorum fault west of the gar basin yields a long term 140 to 20 thousand year right lateral slip rate of 10 7 0 7 millimeters per year this rate is 10 times larger than that inferred from recent insar analyses 1 3 millimeters per year that span 8 years and sample all branches of the fault the difference in slip rate determinations suggests that large rate fluctuations may exist over centennial or millennial time scales such fluctuations would be consistent with mechanical coupling between the seismogenic brittle creep and ductile shear sections of faults that reach deep into the crust

linking morphodynamic response with sediment mass balance on the colorado river in marble canyon issues of scale geomorphic setting and sampling design 1 measurements of morphologic change are often used to infer sediment mass balance such measurements may however result in gross errors when morphologic changes over short reaches are extrapolated to predict changes in sediment mass balance for long river segments this issue is investigated by examination of morphologic change and sediment influx and efflux for a 100 km segment of the colorado river in grand canyon arizona for each of four monitoring intervals within a 7 year study period the direction of sand storage response within short morphologic monitoring reaches was consistent with the flux based sand mass balance both budgeting methods indicate that sand storage was stable or increased during the 7 year period extrapolation of the morphologic measurements outside the monitoring reaches does not however provide a reasonable estimate of the magnitude of sand storage change for the 100 km study area extrapolation results in large errors because there is large local variation in site behavior driven by interactions between the flow and local bed topography during the same flow regime and reach average sediment supply some locations accumulate sand while others evacuate sand the interaction of local hydraulics with local channel geometry exerts more control on local morphodynamic response than sand supply over an encompassing river segment changes in the upstream supply of sand modify bed responses but typically do not completely offset the effect of local hydraulics thus accurate sediment budgets for long river segments inferred from reach scale morphologic measurements must incorporate the effect of local hydraulics in a sampling design or avoid extrapolation altogether

long term behaviour of australian stable continental region scr faults abstract australia boasts arguably the richest late neogene to quaternary faulting record in stable continental region scr crust anywhere in the world variation in fault scarp length vertical displacement proximity to other faults and relationship to topography permits division of the continent according to fault character six onshore neotectonic domains are recognised with an additional offshore domain proposed by analogy with the eastern united states each domain relates to a distinct underlying crustal type and architecture broadly considered to represent cratonic non cratonic and extended environments in general greater topographic expression associated with faults occurring in extended crust relative to non extended crust suggests a higher rate of seismic activity in the former setting consistent with observations worldwide using the same reasoning non cratonic crust might be expected to have a higher rate of seismic activity than cratonic crust this distinction together with the variation in fault character between domains should be recognised in attempts to identify analogous systems worldwide a common characteristic of morphogenic earthquake occurrence in australia appears to be temporal clustering periods of earthquake activity comprising a finite number of large events are separated by much longer periods of seismic quiescence at the scale of a single fault and of proximal faults in several instances there is evidence for deformation at scales of several hundred kilometres switching on and off over the last several million years what is not clear from the limited palaeoseismological data available is whether successive active periods are comparable in terms of slip number of events magnitude of events etc regardless this apparent bimodal recurrence behaviour poses challenges for probabilistic seismic hazard assessment psha these rely on the simplifying assumption that large earthquake recurrence for long return periods is not random i e poissonian presently our ability to incorporate such time dependent models is limited by available data

late quaternary earthquake related soft sediment deformation along the belgian portion of the feldbiss fault lower rhine graben system abstract trench investigations along the bree fault scarp in belgium in the framework of a first paleoseismological experience in the area of the lower rhine graben system have not only demonstrated the existence of seismogenic faults almost extending to the present ground surface but also exposed several types of soft sediment deformation affecting sandy sediments and soils of inferred late weichselian to holocene age the observed features include asymmetric folding small scale normal faulting possible sand intrusions and small water escape or load structures establishing a seismic origin for the individual features is not always possible based on their sedimentary characteristics only particularly due to the potential confusion with periglacial phenomena but their abundance the close association of different deformational styles and their vicinity to a known active fault all seem to be compatible with an earthquake induced scenario the features are to some extent comparable to those generated during the recent ms 5 3 roermond earthquake at the opposite side of the roer valley graben stratigraphical and mutual geometrical relationships suggest the occurrence of at least three distinct deformational events since probably 30 000 years and one event before that time since nothing is yet known about their regional distribution however estimating the associated paleomagnitudes from these soft sediment deformations is premature

quaternary grabens in southernmost illinois deformation near an active intraplate seismic zone abstract narrow grabens displace quaternary sediments near the northern edge of the mississippi embayment in extreme southern illinois east central united states grabens are part of the fluorspar area fault complex fafc which has been recurrently active throughout phanerozoic time the fafc strikes directly toward the new madrid seismic zone nmsz scene of some of the largest intra plate earthquakes in history the nmsz and fafc share origin in a failed cambrian rift reelfoot rift every major fault zone of the fafc in illinois exhibits quaternary displacement the structures appear to be strike slip pull apart grabens but the magnitude and direction of horizontal slip and their relationship to the current stress field are unknown upper tertiary strata are vertically displaced more than 100 m illinoian and older pleistocene strata 10 to 30 m and wisconsinan deposits 1 m or less no holocene deformation has been observed average vertical slip rates are estimated at 0 01 to 0 03 mm year and recurrence intervals for earthquakes of magnitude 6 to 7 are on the order of 10 000s of years for any given fault previous authors remarked that the small amount of surface deformation in the new madrid area implies that the nmsz is a young feature our findings show that tectonic activity has shifted around throughout the quaternary in the central mississippi valley in addition to the nmsz and southern illinois the wabash valley illinois indiana benton hills missouri crowley s ridge arkansas missouri and possibly other sites have experienced quaternary tectonism the nmsz may be only the latest manifestation of seismicity in an intensely fractured intra plate region

tertiary and quaternary tectonic faulting in southernmost illinois abstract tertiary and or quaternary tectonic faulting is documented in three areas of southernmost illinois the fluorspar area fault complex fafc in pope and massac counties the ste genevieve fault zone sgfz in alexander and union counties and the commerce fault zone cfz in alexander county in the fafc faults that strike ne and nne displace mounds gravel late miocene to early pleistocene and locally the metropolis terrace gravel pleistocene pre woodfordian no woodfordian or younger deposits are deformed faults typically outline narrow linear grabens that formed under tension with a component of strike slip north south to nw trending vertical faults near the southeast end of the sgfz displace eocene sediments again faults outline narrow grabens and show indications of strike slip deformed quaternary sediments have not been observed the cfz which trends northeast displaces mounds gravel in illinois and units as young as peoria silt woodfordian in missouri quaternary movement has been interpreted as right lateral strike slip the cfz coincides with a subtle gravity and magnetic lineament and seems to reflect a major feature in the basement surface expression in illinois is subtle but mafic and ultramafic intrusions hydrothermal alteration and small faults align with the commerce geophysical lineament earthquake foci in missouri and illinois lie on or close to the cfz some focal mechanisms fit the fault trend among these structures only the cfz exhibits slip that conforms to the current stress field principal compressive stress axis e w to ene wsw possibly the stress field changed during neogene time alternatively high fluid pressures or local stress concentrations may have induced slip on less favorably oriented fractures tighter constraints are needed on timing magnitude and direction of neogene displacement

large scale erosion rates from in situ produced cosmogenic nuclides in european river sediments abstract we have calculated long term erosion rates of 20 100 mm kyr from quartz contained 10be in the bedload of middle european rivers for catchments ranging from 102 to 105 km2 these rates average over 10 40 kyr and agree broadly with rock uplift incision and exhumation rates historic soil erosion rates and erosion rates calculated from the measured sediment loads of the same rivers moreover our new erosion rate estimates correlate well with lithology and relief however in the regen neckar loire and meuse catchments cosmogenic nuclide derived erosion rates are consistently 1 5 4 times greater than the equivalent rates derived from measured river loads this may be due to the systematic under representation of high magnitude low frequency transport events in the gauging records which cover less than a century alternatively the discrepancy may derive from spatially non uniform erosion and preferential tapping of deeper sections of the irradiation profile a third explanation relates the high cosmogenic nuclide derived erosion rates to inheritance of an elevated pleistocene erosion signal uncertainties associated with the cosmogenic nuclide derived erosion rate estimates are not greater than the potential errors in conventional estimates therefore the cosmogenic nuclide approach is an effective tool for rapid catchment wide assessment of time integrated rates of bedrock weathering and erosion and we anticipate its fruitful application to the quaternary sedimentary record

late quaternary evolution of the feldbiss fault roer valley rift system the netherlands based on trenching and its potential relation to glacial unloading abstract the most important tectonic structure in the southern part of the netherlands is the roer valley rift system rvrs the main border fault zones of the rvrs the peel boundary and the feldbiss fault zones have been active during the quaternary and are still active today as indicated by the occurrence of earthquakes in this paper we present the results of a trench across the feldbiss fault part of the feldbiss fault zone this trench provided no evidence for earthquakes along this segment of the fault zone fluidization structures were not encountered a sudden increase in the average fault displacement rate was inferred for the period around 15 ka b p in a trench nearby across the geleen fault of the same fault zone the limited age control cannot exclude that such an acceleration also occurred at the feldbiss fault during the second half of the 1990 s several paleoseismological trenching studies have been carried out in the rvrs the compilation of the results of these studies reveals that the main border faults possibly experienced an increase in fault activity around 10 15 ka b p the timing of this increased activity and results from glacial rebound modelling indicate that glacial unloading of the crust can have triggered this increase in fault activity

pulsed strain release on the altyn tagh fault northwest china abstract earthquake recurrence models assume that major surface rupturing earthquakes are followed by periods of reduced rupture probability as stress rebuilds although purely periodic time or slip predictable rupture models are known to be oversimplifications a paucity of long records of fault slip clouds understanding of fault behavior and earthquake recurrence over multiple ruptures here we report a 16 kyr history of fault slip including a pulse of accelerated slip from 6 4 to 6 0 ka determined using a monte carlo analysis of well dated offset landforms along the central altyn tagh strike slip fault atf in northwest china this pulse punctuates a median rate of 8 1 1 2 0 9 mm a and likely resulted from either a flurry of temporally clustered mw 7 5 ground rupturing earthquakes or a single large mw 8 2 earthquake the clustered earthquake scenario implies rapid re rupture of a fault reach 195 km long and indicates decoupled rates of elastic strain energy accumulation versus dissipation conceptualized as a crustal stress battery if the pulse reflects a single event slip magnitude scaling implies that it ruptured much of the atf with slip similar to or exceeding the largest documented historical ruptures both scenarios indicate fault rupture behavior that deviates from classic time or slip predictable models

interplay between climatic tectonic and anthropogenic forcing in the lower rhine graben the roer river the roer is a small river which drains the rhenish shield and confluences with the meuse river up to now the geological climatological biostratigraphical and pedological setting of the roer valley were not sufficiently integrated to disentangle the effects of external forcing factors on the roer river in this study we perform a detailed and integrated reconstruction of the fluvial morphology and palaeogeography of the roer river in order to determine responses to combined climatic tectonic and anthropogenic forcing factors the roer river has formed five terrace levels since the weichselian late pleniglacial fluvial planform of the roer river was predominantly climate controlled during the lateglacial and early holocene reach to reach variations in river terrace formation and fluvial planform change occur due to variations in tectonic setting subsurface geology base level fluctuations and the confluence with tributary systems differential subsidence by active faulting in the roer valley graben during the early lateglacial caused a preferential usage of the down tilt channels of the up to then double channel belt systems in the roer valley this preferred channel avulsion towards a fault zone leaving an underfit system on the up tilted side and the clustering of holocene roer channels along that fault zone meet the criteria for a lateral response of the roer river to a tectonic forcing anthropogenic influences in the form of deforestation and land use changes during the late holocene are responsible for the formation of a final terrace level and overbank sediments 2019 elsevier b v

predicting boundary shear stress and sediment transport over bed forms to estimate bed load sediment transport rates in flows over bed forms such as ripples and dunes spatially averaged velocity profiles are frequently used to predict mean boundary shear stress however such averaging obscures the complex nonlinear interaction of wake decay boundary layer development and topographically induced acceleration downstream of flow separation and often leads to inaccurate estimates of boundary stress particularly skin friction which is critically important in predicting skin friction over 2d bed forms the approach is based on combining the equations describing the mechanics of the internal boundary layer with semi empirical structure functions to predict the velocity at the crest of a bed form where the flow is most similar to a uniform boundary layer significantly the methodology is directed toward making specific predictions only at the bed form crest and as a result it avoids the difficulty and questionable validity of spatial averaging the model provides an accurate estimate of the skin friction at the crest where transport rates are highest simple geometric constraints can be used to derive the mean transport rates as long as bedload is dominant

role of near bed turbulence structure in bed load transport and bed form mechanics the interactions between turbulence events and sediment motions during bed load transport were studied by means of laser doppler velocimetry and high speed cinematography sweeps u 0 w 0 w 0 which contribute negatively to the bed shear stress and are relatively rare individually move as much sediment as sweeps of comparable magnitude and duration however and much more than bursts u 0 and inward interactions u 0 w 0 when the magnitude of the outward interactions increases relative to the other events therefore the sediment flux increases even though the bed shear stress decreases thus although bed shear stress can be used to estimate bed load transport by flows with well developed boundary layers in which the flow is steady and uniform and the turbulence statistics all scale with the shear velocity it is not accurate for flows with developing boundary layers such as those over sufficiently nonuniform topography or roughness in which significant spatial variations in the magnitudes and durations of the sweeps bursts outward interactions and inward interactions occur these variations produce significant peaks in bed load transport downstream of separation points thus supporting the hypothesis that flow separation plays a significant role in the development of bed forms

high resolution seismic imaging of outcrop scale channels and an incised valley system within the fluvial dominated lower freshwater molasse aquitanian western swiss molasse basin abstract high resolution seismic reflection surveys on lake geneva near lausanne switzerland allow the interpretation of outcrop scale sedimentary features within the fluvial dominated lower miocene lower freshwater molasse bedrock seismic modelling of an outcrop is used to calibrate the seismic data and assist with interpretation seismic resolution is sufficient to image sandstone channel fill complexes 4 5 m thick five seismic facies are recognized and interpreted as fluvial architectural elements of the lower freshwater molasse two of these facies are characterized by fairly continuous reflections of variable frequency and low to moderate amplitude interpreted as metre thick channel fill complexes the lateral extent of such channels ranges from 100 to 170 m the other three seismic facies are characterized by moderate to high amplitude sub parallel continuous reflections the three facies are mainly distinguished using reflection frequency and continuity they correspond to distinct floodplain settings i e proximal intermediate and distal with respect to the active channel belt on a larger scale a portion of a ca 50 m deep incised valley system probably caused by a relative base level fall was identified two distinct valley fill units are recognized the lower unit was interpreted as comprising valley edge slump units by comparison with outcrop data the upper unit is interpreted as the fluvial fill deposited in the most landward portion of the valley

erosion of sand from a gravel bed abstractcleaning of fine sediment out of gravel streambeds has become an important method to restore affected stream habitats introducing the increased flows needed to entrain fine sediments without eroding the coarser fractions of the bed and potentially destroying its usefulness as a habitat requires careful selection of flow strength toward this end a series of flume experiments was conducted on the entrainment of sand from immobile gravel beds to determine the depth to which the sand could be eroded without the gravel being mobilized a series of steady flows was imposed on three gravel beds filled with sand with median sizes of 0 2 0 3 and 0 9 mm the shear stress of the series of flows ranged from just above the critical shear stress for initiation of motion of the sand up to 0 9 times the critical stress of the 36 1 mm gravel the experiments continued until the rate of fine sediment exiting the channel was very small it was found that the cleanout depth of the sand was reasonably predicted b

velocity distribution and bed roughness in high gradient streams a model for the velocity field over a poorly sorted bed is derived herein and applied to flow in steep streams with coarse gravel beds in such streams large clasts often are comparable in size to stream depth and act as obstacles to the flow the effect of these obstacles on a flow is estimated by partitioning total stress proportional to the depth slope product into a purely fluid component and a form drag component associated with flow around the obstacles an eddy viscosity closure is used with a length scale dependent on both distance from the boundary and wake dimension resulting velocity profiles agree well with profiles measured by marchand et al 1984 in nine mountain streams in colorado model runs for a range of conditions reveal that the velocity distribution depends primarily on d84z and flow depth h d84z is the length of the vertically oriented axis of clasts at the 84th percentile of the grain size distribution calculated values of mean velocity normalized by shear velocity are well represented by a simple log linear relationship in terms of relative roughness d84 h

geological and geophysical evidence for large palaeo earthquakes with surface faulting in the roer graben northwest europe from the analysis of geological geodetic and geophysical data we provide clear evidence of seismogenic faults capable of producing large earthquakes in intraplate europe previous studies paulissen vandenberghe gullentops 1985 van den berg et al 1994 geluk et al 1994 have yielded some constraints on the rate of crustal deformation along the roer valley a graben structure crossing the netherlands belgium and germany and have allowed us to address the fundamental questions can intraplate earthquakes rupture the surface in this part of stable continental europe and if so what is their return period detailed palaeoseismic investigations have been carried out in belgium along a 10 km long fault scarp which is the morphological expression of the feldbiss fault the southwestern border fault of the roer graben camelbeeck meghraoui 1996 the scarp is multiple and the frontal fault scarp offsets young deposits and alluvial terraces field investigations using geological and geomorphological methodologies combined with geophysical prospecting provide evidence of holocene seismic surface faulting from 14c dating it is suggested that the last earthquake along the fault scarp occurred between 610 ad and 890 ad levelling profiles across the scarp suggest that it produced a vertical coseismic displacement of 0 5 1 m along the scarp if we suppose that the last surface faulting earthquake ruptured the whole seismogenic layer 17 km thickness over a minimum length 10 km corresponding to the length of the bree scarp with an average slip of 0 6 m its seismic moment was at least 3 1 1018 n m mw 6 3 for an average rigidity 3 1010 pa by estimating the offset of the main terrace of the maas river by slippage along the feldbiss fault we calculate the average late pleistocene vertical deformation rate as 0 08 0 04 mm yr 1 palaeoseismic information combining the trench and geomorphic observations suggests the occurrence of two surface faulting earthquakes during the last 20 kyr a third dates before 28 35 kyr bp then if the time distribution of earthquakes is uniform a return period of 12 5 ka and a vertical deformation rate of 0 06 0 04 mm yr 1 are inferred

denali fault slip rates and holocene late pleistocene kinematics of central alaska the denali fault is the principal intracontinental strike slip fault accommodating deformation of interior alaska associated with the yakutat plate convergence we obtained the first quantitative late pleistocene holocene slip rates on the denali fault system from dating offset geomorphic features analysis of cosmogenic 10be concentrations in boulders n 27 and sediment n 13 collected at seven sites offset 25 170 m by the denali and totschunda faults gives average ages that range from 2 4 0 3 ka to 17 0 1 8 ka these offsets and ages yield late pleistocene holocene average slip rates of 9 4 1 6 12 1 1 7 and 8 4 2 2 mm yr 1 along the western central and eastern denali fault respectively and 6 0 1 2 mm yr 1 along the totschunda fault our results suggest a westward decrease in the mean pleistocene holocene slip rate this westward decrease likely results from partitioning of slip from the denali fault system to thrust faults to the north and west

tectonic history of the illinois basin the illinois basin began as a failed rift that developed during breakup of a supercontinent approximately 550 ma a rift basin in the southernmost part of the present illinois basin subsided rapidly and filled with about 3 000 m of probable early and middle cambrian sediments by the late cambrian the rift bounding faults became inactive and a broad relatively slowly subsiding embayment extending well beyond the rift and open to the iapetus ocean persisted through most of the paleozoic era widespread deformation swept through the proto illinois basin beginning in the latest mississippian continuing to the end of the paleozoic era uplift of basement fault blocks resulted in the formation of many major folds and faults the timing of deformation and location of these structures in the forelands of the ouachita and alleghanian orogenic belts suggest that much of the deformation resulted from continental collision between north america and gondwana the associated compressional stress reactivated the ancient rift bounding faults upthrusting the northern edge of a crustal block approximately 1 000 m within the rift concurrently dikes radiometrically dated as early permian sills and explosion breccias formed in or adjacent to the reactivated rift subsequent extensional stress probably associated with breakup of pangea causedmore the crustal block within the rift to sink back to near its original position high angle northeast to east west trending normal faults with as much as 1 000 m of displacement formed in the southern part of the basin these faults displace some of the northwest trending early permian dikes structural closure of the southern end of the illinois basin was caused by uplift of the pascola arch sometime between the late pennsylvanian and late cretaceous less

the cenozoic lower rhine basin rifting sedimentation and cyclic stratigraphy in the cenozoic the lower rhine basin formed as a rift at the southeastern terminus of the dutch german central graben while the rhenish massif was uplifted the study focusses on the marginal marine and fluvial fill of the lower rhine basin a basin model is developed support for this study was given by extensive industry outcrop and well data by new stratigraphical and sedimentological observations the ingression and subsequent regression of the cenozoic north sea is analysed using the concept of base level cyclicity as the geohistory of the basin was complex a subsidence curve is constructed furthermore an attempt is made to trace the simultaneous uplift of the rhenish massif

seismic reflection imaging of tertiary faulting and related post eocene deformation 20 km north of memphis tennessee abstract other than the crittenden county fault zone ccfz little is known about the seismic hazard from earthquake faults within 50 km of memphis tennessee a city that contains a large inventory of older buildings that are vulnerable to moderate and strong earthquake ground shaking to address this lack of knowledge about faulting near memphis we acquired a 4 5 km long mini sosie seismic reflection profile across the boundary between the loess covered bluffs and modern mississippi river flood plain in meeman shelby forest state park north of memphis we imaged a previously unknown reverse thrust fault that displaces paleozoic and cretaceous rocks and upwarps tertiary deposits on the floodplain portion of the profile about 25 km north of downtown memphis the paleozoic and cretaceous rocks are vertically faulted about 70 and 40 m respectively in an up to the west sense of displacement the fault displacement apparently terminates in the basal portion of the paleocene section and causes only an upwarping of the overlying deposits the overlying paleocene and eocene deposits which are probably the youngest deposits imaged are upwarped about 50 60 m with the same sense of displacement as the underlying older units the sense of displacement amplitude and appearance of the fault in the seismic data are very similar to that observed in the seismic reflection images of the ccfz 15 km west of this profile although we have imaged this new fault in only one location its proximity to memphis and similarities to the ccfz leads us to speculate that it may be a parallel structure to the ccfz and thus warrants further study

the pliocene and quaternary fluvial archives of the rhine system abstract the river rhine is one of the few major fluvial systems that connect the areas of the alpine glaciers and scandinavian ice sheet and so provides a key for correlating the two glacial areas in northern and middle europe the fluvial sequences of the rhine valley include at least 11 pleistocene terraces in the lower rhine area 2 pliocene and 12 pleistocene terraces in the middle rhine area resulting in 15 different pliocene and pleistocene terraces based on the correlation between lower and middle rhine the formation of fluvial terraces is significantly influenced by climatic and tectonic processes the terrace staircases are a result of uplift in the middle rhine area and the southern part of the lower rhine area whereas subsidence in the northern part of the lower rhine area resulted in buried stacked sequences magnetostratigraphic data provide chronological constraints for the terrace deposits in the lower rhine embayment and middle rhine region the matuyama brunhes boundary is a reliable marker horizon for the upper terrace fluvial deposits exposed in the karlich clay pit in the middle rhine area the first appearance of volcanic heavy mineral grains in the terrace sediments in loess and soils can be correlated from the middle rhine area through the lower rhine embayment to the netherlands the first occurrence of nordic components in terrace sediments of the lower rhine area is known from gravel on top of the kempen krefeld beds and so are younger than the holsteinian but older than the penultimate glaciation in the lower middle rhine area 40ar 39ar dating of tephra layers intercalated in the aeolian and fluvial sediments provide age constraints the upper pleistocene aeolian sediments overlying the terrace deposits have been dated by luminescence methods and the tephra from the laacher see eruption 12 860 bp is present in the younger lower terrace deposits

commerce geophysical lineament its source geometry and relation to the reelfoot rift and new madrid seismic zone the commerce geophysical lineament is a northeast trending magnetic and gravity feature that extends from central arkansas to southern illinois over a distance of 400 km it is parallel to the trend of the reelfoot graben but offset 40 km to the northwest of the western margin of the rift floor modeling indicates that the source of the aeromagnetic and gravity anomalies is probably a mafic dike swarm the age of the source of the commerce geophysical lineament is not known but the linearity and trend of the anomalies suggest a relationship with the reelfoot rift which has undergone episodic igneous activity the commerce geophysical lineament coincides with several topographic lineaments movement on associated faults at least as young as quaternary and intrusions of various ages several earthquakes m b 3 coincide with the commerce geophysical lineament but the diversity of associated focal mechanisms and the variety of surface structural features along the length of the commerce geophysical lineament obscure its relation to the release of present day strain with the available seismicity data it is difficult to attribute individual earthquakes to a specific structural lineament such as the commerce geophysical lineament however the close correspondence between quaternary faulting and present day seismicity along the commerce geophysical lineament is intriguing and warrants further study

shallow seismic reflection profiles and geological structure in the benton hills southeast missouri abstract during late may and early june of 1993 we conducted two shallow high resolution seismic reflection surveys mini sosie method across the southern escarpment of the benton hills segment of crowleys ridge the reflection profiles imaged numerous post late cretaceous faults and folds we believe these faults may represent a significant earthquake source zone the stratigraphy of the benton hills consists of a thin less than about 130 m sequence of mostly unconsolidated cretaceous tertiary and quaternary sediments which uncomfortably overlie a much thicker section of paleozoic carbonate rocks the survey did not resolve reflectors within the upper 75 100 ms of two way travel time about 60 100 m which would include all of the tertiary and quaternary and most of the cretaceous however the paleozoic cretaceous unconformity pz produced an excellent reflection and locally a shallower reflector within the cretaceous k was resolved no coherent reflections below about 200 ms of two way travel time were identified numerous faults and folds which clearly offset the paleozoic cretaceous unconformity reflector were imaged on both seismic reflection profiles many structures imaged by the reflection data are coincident with the surface mapped locations of faults within the cretaceous and tertiary succession two locations show important structures that are clearly complex fault zones the english hill fault zone striking n30 35 e is present along line 1 and is important because earlier workers indicated it has pleistocene loess faulted against eocene sands the commerce fault zone striking n50 e overlies a major regional basement geophysical lineament and is present on both seismic lines at the southern margin of the escarpment the fault zones imaged by these surveys are 30 km from the area of intense microseismicity in the new madrid seismic zone nmsz if these are northeast and north northeast oriented fault zones like those at thebes gap they are favorably oriented in the modern stress field to be reactivated as right lateral strike slip faults currently earthquake hazards assessments are most dependent upon historical seismicity and there are little geological data available to evaluate the earthquake potential of fault zones outside of the nmsz we anticipate that future studies will provide evidence that seismicity has migrated between fault zones well beyond the middle mississippi valley the potential earthquake hazards represented by faults outside the nmsz may be significant

sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads the rio grande in the big bend region of texas usa and chihuahua and coahuila mexico undergoes rapid geomorphic changes as a result of its large sediment supply and variable hydrology thus it is a useful natural laboratory to investigate the relative importance of flow strength and sediment supply in controlling alluvial channel change we analyzed a suite of sediment transport and geomorphic data to determine the cumulative influence of different flood types on changing channel form in this study physically based analyses suggest that channel change in the rio grande is controlled by both changes in flow strength and sediment supply over different spatial and temporal scales channel narrowing is primarily caused by substantial deposition of sediment supplied to the rio grande during tributary sourced flash floods tributary floods have large suspended sediment concentrations occur for short durations and attenuate rapidly downstream in the rio grande depositing much of their sediment in downstream reaches long duration floods on the mainstem have the capacity to enlarge the rio grande and these floods released from upstream dams can either erode or deposit sediment in the rio grande depending upon the antecedent in channel sediment supply and the magnitude and duration of the flood geomorphic and sediment transport analyses show that the locations and rates of sand erosion and deposition during long duration floods are most strongly controlled by spatial changes in flow strength largely through changes in channel slope however spatial differences in the in channel sediment supply regulate sediment evacuation or accumulation over time in long reaches greater than a kilometer

equilibrium entrainment of fine sediment over a coarse immobile bed 1 the transported load in most fluvial systems including gravel bedded rivers includes fine grained sediment models for suspended sediment transport have focused on sand covered beds rendering incomplete the theoretical and empirical framework for predicting fine sediment transport and routing we conducted laboratory experiments involving sand transport over large immobile grains the experiments were scaled such that immobile particles were much larger than the mobile sediment but less than 10 of flow depth and that bed shear stresses scaled by the size of the mobile sediment were indicative of transport in suspension the experiments were conducted in equilibrium transport and included measurements of near bed sediment concentration and interstitial sand storage for a range of flow and transport rates partial filling of grain interstices occurred over a narrow range of flow and transport rates indicating a sharp threshold between no interstitial sand storage and a sand covered bed less sand coverage on the bed resulted in higher near bed sand concentrations per unit area of sand than runs with greater sand coverage as sand bed elevation decreased relative to the coarse grains turbulent wakes shed by the large grains appeared to enhance grain entrainment more than the corresponding decrease in bed area covered by sand resulted in decreased entrainment elevated concentrations were maintained until the bed was depleted of fine sediment these results are formalized in a proposed sand elevation correction function that scales the entrainment rate for a bed partially covered by sand to the entrainment rate that would be predicted for a sand covered bed

comparison of geodetic and geologic data from the wasatch region utah and implications for the spectral character of earth deformation at periods of 10 to 10 million years the wasatch fault and adjacent fault zones provide an opportunity to compare present day deformation rate estimates obtained from space geodesy with geologic displacement rates over at least four temporal windows ranging from the last millennium up to 10 myr the three easternmost gps sites of the basin and range geodetic network bargen at this latitude define a 130 km wide region spanning three major normal faults extending east west at a total rate of 2 7 0 4 mm yr with an average regional strain rate estimated to be 21 4 nstrain yr about twice the basin and range average on the wasatch fault the vertical component of the geologic displacement rate is 1 7 0 5 mm yr since 6 ka 0 6 mm yr since 130 ka and 0 5 0 7 mm yr since 10 ma however it appears likely that at the longest timescale rates slowed over time from 1 0 to 1 4 mm yr between 10 and 6 ma to 0 2 to 0 3 mm yr since 6 ma the cumulative vertical displacement record across all three faults also shows time variable strain release ranging from 2 to 4 mm yr since 10 ka to 1 mm yr averaged over the past 130 kyr conventional earthquake recurrence models reid type behavior would require an accordingly large variation in strain accumulation or loading rate on a 10 kyr timescale for which there appears to be no obvious geophysical explanation alternatively seismic strain release given a wide range of plausible constitutive behaviors for frictional sliding may be clustered on the 10 kyr timescale resulting in the high holocene rates with comparatively low uniform strain accumulation rates on the 100 kyr timescale wallace type behavior the latter alternative combined with observations at the million year timescale and the likelihood of a significant contribution of postseismic transients implies maxima of spectral amplitude in the velocity field at periods of 10 myr variations in tectonic loading 10 kyr clustered strain release and of 100 years postseismic transients if so measurements of strain accumulation and strain release may be strongly timescale dependent for any given fault system

shallow seismic imaging of folds above the puente hills blind thrust fault los angeles california 1 high resolution seismic reflection profiles image discrete folds in the shallow subsurface 600 m above two segments of the puente hills blind thrust fault system los angeles basin california the profiles demonstrate late quaternary activity at the fault tip precisely locate the axial surfaces of folds within the upper 100 m and constrain the geometry and kinematics of recent folding the santa fe springs segment of the puente hills fault zone shows an upward narrowing kink band with an active anticlinal axial surface consistent with fault bend folding above an active thrust ramp the coyote hills segment shows an active synclinal axial surface that coincides with the base of a 9 m high scarp consistent with tip line folding or the presence of a backthrust the seismic profiles pinpoint targets for future geologic work to constrain slip rates and ages of past events on this important fault system

the roman eifel aqueduct archaeoseismological evidence for neotectonic movement at the transition of the eifel to the lower rhine embayment the lower rhine embayment and adjacent areas are characterised by neotectonic deformation resulting in differential crustal movement slip rates along the fault systems are very low 0 1 mm a significant earthquakes are known to have occurred in the past but the faulting behaviour is not adequately known which hampers the risks assessment we analysed the archaeological record of the largest roman aqueduct north of the alps this so called eifel aqueduct is 95 4 km long has its source in the eifel mountains and supplied the ancient city of cologne with calcareous fresh water the aqueduct crosses major faults of the lower rhine embayment perpendicular analyses of the aqueduct s gradient gives weak evidence for creep along the kirspenich fault resulting in differential movement of hanging and foot wall in the order of a few centimetres vertical offsets of 15 and 35 cm are documented exactly where the aqueduct crosses the holzheim fault system close to the city of mechernich here also structural damage of the aqueduct is recorded and archaeological evidence exists for repair works on the aqueduct we interpret these observations as well as the construction of a 4 km long deviation as necessary measures to keep the aqueduct operational after earthquake damage the timing of the event falls within the period of aqueduct operation which is reconstructed to be between 80 10 and 270 10 ce supporting evidence for earthquake activity within this period is seen in the roof collapse of the nearby kakus cave

late quaternary paleoseismology and faulting behavior of the yilan yitong fault zone and implications for seismic hazards of the tanlu fault zone eastern china abstract along the north branch of the tanlu fault zone tlfz the yilan yitong fault zone yyfz displaces quaternary geomorphic features forming a 70 km long fresh surface rupture in this study we investigated offset landforms and paleoearthquake history by excavating four trenches along the yyfz within the fangzheng graben combined with quaternary dating of landforms and trench horizons four paleoearthquakes are identified with their timings constrained at 1730 40 a bp to 770 30 a bp 28 5 1 2 ka bp to 21 7 0 9 ka bp 59 4 2 4 ka bp to 33 1 1 1 ka bp and before 59 4 2 4 ka bp respectively seismic recurrence behavior of the yyfz follows a quasi periodic pattern with a very long interval of 10 20 ka geological and geomorphic features show that the yyfz is dominated by right lateral strike slip movement with a low dextral slip rate of 0 2 0 3 mm a in late quaternary in accord with present day geodetic observations as with the yyfz paleoearthquakes along the tlfz commonly share a recurrence interval of 10 20 ka we suggest that active segments of the tlfz that have been dormant for thousands of years may pose significant earthquake hazards in the future moreover strain transfer from the bounding faults to those more central in the graben may be significant on the tlfz and should be given consideration when assessing regional seismic hazards insight into past earthquakes and faulting behavior in a low strain environment is crucial for earthquake hazard analysis and often requires multidisciplinary approaches

variable post paleozoic deformation detected by seismic reflection profiling across the northwestern prong of new madrid seismic zone abstract high resolution shallow seismic reflection profiles across the northwesternmost part of the new madrid seismic zone nmsz and northwestern margin of the reelfoot rift near the confluence of the ohio and mississippi rivers in the northern mississippi embayment reveal intense structural deformation that apparently took place during the late paleozoic and or mesozoic up to near the end of the cretaceous period the seismic profiles were sited on both sides of the northeast trending olmsted fault defined by varying elevations of the top of mississippian locally base of cretaceous bedrock the trend of this fault is close to and parallel with an unusually straight segment of the ohio river and is approximately on trend with the westernmost of two groups of northeast aligned epicenters prongs in the nmsz initially suspected on the basis of pre existing borehole data the deformation along the fault has been confirmed by four seismic reflection profiles combined with some new information from drilling the new data reveal 1 many high angle normal and reverse faults expressed as narrow grabens and anticlines suggesting both extensional and compressional regimes that involved the largest displacements during the late cretaceous mcnairy 2 a different style of deformation involving probably more horizontal displacements i e thrusting that occurred at the end of this phase near the end of mcnairy deposition with some fault offsets of paleocene and younger units 3 zones of steeply dipping faults that bound chaotic blocks similar to that observed previously from the nearby commerce geophysical lineament cgl and 4 complex internal deformation stratigraphically restricted to the mcnairy suggestive of major sediment liquefaction or landsliding our results thus confirm the prevalence of complex cretaceous deformations continuing up into tertiary strata near the northern terminus of the nmsz

deriving fault slip histories to test for secular variation in slip with examples from the kunlun and awatere faults abstract although offset and age data from displaced landforms are essential for identifying earthquake clusters and thus testing whether faults slip at uniform or secularly varying rates it is not clear how the uncertainties in such measurements should be propagated so as to yield a robust fault slip history i e record of fault displacement over time here we develop a monte carlo approach for estimating the distribution of geologically reasonable fault slip histories that fit the offset and age data from a population of dated and displaced landforms the model assumes that the landforms share common faulting histories the offset and age constraints are correct and the fault has not reversed shear sense analysis of the model results yields both a precise average slip rate in the case where a linear fit is applied to the data and a best fit fault slip history in the case where the linear constraint is removed the method can be used to test for secular variation in slip because the uncertainty on this best fit history is quantified by applying the method to previously published morphochronologic data from faulted late quaternary terrace risers along the kunlun fault in china and the awatere fault in new zealand we have assessed the extent to which our modeled average slip rates match previously reported values and the data support previous interpretations of uniform slip rate the kunlun data set yields average slip rates of 8 7 3 6 2 1 mm yr and 5 1 1 6 1 2 mm yr 68 27 confidence for the central and eastern reaches of the fault respectively both of which match previously published slip rates our analysis further indicates that these fault reaches have both slipped uniformly over the latest quaternary in contrast analysis of data from the saxton river site along the awatere fault reveals a mid holocene deceleration in slip rate from 6 2 1 6 1 4 mm yr to 2 8 1 0 0 6 mm yr this result contradicts previous interpretations of uniform slip along the awatere fault the monte carlo method we present here for quantifying fault slip histories using the offset and age data from a population of faulted landforms provides an important tool for distinguishing temporally uniform from secularly varying fault slip

development of deflation lag surfaces a series of wind tunnel tests were carried out to investigate the development of deflation lags in relation to the non erodible roughness element concentration glass spheres 18 mm in diameter were placed along the complete length of the wind tunnel working section in regular staggered arrays using three different spacings d 18 30 and 60 mm and completely covered with a 0 27 mm erodible sand a pre selected free stream velocity above threshold 8m s 1 was established above the surface and the sediment transport measured at 2 s intervals using a wedge shaped trap in which an electronic balance is incorporated throughout each test the emerging lag surface was periodically photographed from above at two locations upwind of the trap the photographs were electronically scanned and analysed to calculate the lag element coverage and location as well as mean height and frontal area for each time period test results indicate that lag development has a profound effect on both the sediment flux and wind profile characteristics initially there is an increase in sediment flux above that for a rippled sand bed because of increased erosion around and reduced kinetic energy loss in highly elastic collisions with the emerging roughness elements with further emergence a dynamic threshold is reached whereupon the sediment flux decreases rapidly tending towards zero at this point the supply of grains to the air stream through fluid drag follows a reduction in aerodynamic roughness and therefore surface shearing stress at least as important is the lesser potential for grain ejection at impact because of reduced momentum imparted from the air stream during saltation although recent shear stress partitioning models indicate when particle movement may commence on varying surfaces our experimental results demonstrate that this partitioning has a further direct bearing upon the saltation flux ratio

lithospheric elasticity promotes episodic fault activity based on the agreement between geodetic and geological plate velocities interplate fault slip rates are usually considered constant over long periods of time however measurements made at different time scales on intracontinental faults suggest that slip rate evolves with time we examine the slip evolution of a fault embedded in an elastic lithosphere loaded by plate motion we first assume that the fault friction varies due to a climatic cause then we show that high fault stress and low lithospheric stiffness favour large variations of slip rate in the case where fault weakening is controlled by slip rate we find that high loading velocity leads to a low stress constant slip rate while low loading velocity drives the fault slip rate to cycle between high and low values this suggests that paleoseismic slip rate could overpass the loading velocity but also fall to zero for some period of time

significant motions between gps sites in the new madrid region implications for seismic hazard position time series from global positioning system gps stations in the new madrid region were differenced to determine the relative motions between sta tions uncertainties in rates were estimated using a three component noise model con sisting of white flicker and random walk noise following the methodology of langbein 2004 significant motions of 0 37 0 07 one standard error mm yr were found between sites ptgvand stle for which the baseline crosses the inferred deep portion of the reelfoot fault baselines between stle and three other sites also show significant motion site mcty adjacent to stle also exhibits significant motion with respect to ptgv these motions are consistent with a model of interseismic slip of about 4 mm yr on the reelfoot fault at depths between 12 and 20 km if constant over time this rate of slip produces sufficient slip for an m 7 3 earthquake on the shallow portion of the reelfoot fault using the geologically derived recurrence time of 500 years this model assumes that the shallow portion of the fault has been pre viously loaded by the intraplate stress a gps site near little rock arkansas shows significant southward motion of 0 3 0 4 mm yr 0 08 mm yr relative to three sites to the north indicating strain consistent with focal mechanisms of earthquake swarms in northern arkansas

fault displacement rates on a range of timescales abstract displacements on tectonic faults primarily accrue during earthquakes at rates that vary through time to examine the processes that underlie the temporal changes in fault displacement rates we analyse displacements and displacement rates for time periods from the present to 5 10 20 300 500 1000 and 5000 kyr for 261 active reverse or normal faults from a worldwide dataset displacement rates depart from million year average rates by up to three orders of magnitude with the size of these departures inversely related to the duration of the sample period and to fault length short term 20 kyr displacement rates generally span a greater range on small faults than large a feature which suggests more variable growth on smaller faults simple earthquake slip modeling shows that variations in displacement rates require changes in both recurrence interval and slip per event and do not support the characteristic slip earthquake model as long as fault system strain rates are uniform displacement rates generally become constant over time periods between 20 and 300 kyr with the length of time required to reach stability being inversely related to the regional basin wide strain rates stable long term displacement rates and fluctuations in earthquake recurrence intervals and slip arise in part due to fault interactions

deformation and quaternary faulting in southeast missouri across the commerce geophysical lineament abstract high resolution seismic reflection data acquired at three sites along the surface projection of the commerce geophysical lineament in southeast missouri reveal a complex history of post cretaceous faulting that has continued into the quaternary near qulin missouri approximately 20 m of apparent vertical fault displacement has occurred in the quaternary reflection data collected at idalia hill about 45 km to the northeast reveal a series of reverse and possibly right lateral strike slip faults with quaternary displacement in the benton hills 45 km northeast of idalia hill seismic data image a complicated series of anticlinal and synclinal fault bounded blocks immediately north of the commerce fault we infer that most of the deformation imaged in the upper 400 m of these three data sets occurred since post cretaceous time and a significant portion of it occurred during quaternary time collectively these seismic data along with geomorphic and surface geologic evidence suggest 1 the existence of at least one potential seismogenic structure in southeastern missouri outside the main zones of new madrid seismicity and 2 these structures have been active during the quaternary the geographic location of the imaged deformation suggests it is related to structures along with the commerce geophysical lineament

effects of sand addition on turbulent flow over an immobile gravel bed 1 the factors controlling the complex interaction of a coarse streambed with flow and sediment are difficult to measure however planning for reservoir flushing or dam removal requires knowledge of these interactions in both cases impounded sediments are introduced to channel beds that have had fine sediment particles removed without replacement the channel bed pore space interacts with the flow and provides storage for particles in order to address the need for information on such systems an adjustable slope recirculating laboratory flume was used to study the changes in flow and turbulence caused by sand added to an immobile gravel bed detailed measurements were made using an acoustic doppler velocimeter that collected three velocity components at a rate of 200 hz because of the rough nature of the bed individual velocity profiles varied significantly therefore in order to determine general trends the data were spatially averaged over six 10 20 cm planes parallel to the bed with the lowest plane about 2 cm below the maximum gravel elevation the increasing elevation of sand relative to the gravel layer resulted in decreased bed shear stress decreased reynolds stress increased relative turbulence intensity and a near bed shift toward sweep dominated turbulence

sand transport over an immobile gravel substrate abstractexperiments were conducted in a laboratory flume channel to evaluate the effects of increasing amounts of sand on its transport over and through an immobile coarse gravel bed detailed measurements of sand transport rate bed texture and bed topography were collected for four different discharges at approximately the same flow depth of 0 2 m for 11 different elevations of sand in the gravel bed sand transport was measured using both physical samples and a density cell for a given flow rate increases in the elevation of sand relative to gravel resulted in decreases of bed shear stress from 32 44 and increases in sand transport by three orders of magnitude for the highest two discharges the sand merged into a small number of long and low bed forms that translated through and over the gravel bed a collapse of the transport data was accomplished by relating the sand transport rate to the bed shear stress scaled by the cumulative probability distribution function of the gravel surface evaluated

time variable deformation in the new madrid seismic zone new geodetic measurements show that the new madrid is currently deforming too slowly if at all to account for large earthquakes in the region over the past 5000 years this result together with increasing evidence for temporal clustering and spatial migration of earthquake sequences in continental interiors indicates that either tectonic loading rates or fault properties vary over a few thousand years

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

crustal velocity field of western europe from permanent gps array solutions 1996 2001 we derive a new geodetic velocity field for western europe and the western mediterranean by rigorously combining 1 a selection of 36 itrf2000 sites 2 a solution from a subset of sites of the european permanent gps network euref epn 3 a solution of the french national geodetic permanent gps network rgp and 4 a solution of a permanent gps network in the western alps regal the resulting velocity field describes horizontal crustal motion at 64 sites in western europe with an accuracy of the order of i mm yr 1 or better its analysis shows that central europe defined as east of the rhine graben and north of the alps and the carpathians behaves rigidly at a 0 4 mm yr 1 level and defines a stable europe reference frame in that reference frame we find no significant motion at sites located west of the rhine graben and on the iberian peninsula which sets an upper bound of 0 6 mm yr 1 on horizontal motion across the rhine graben and the pyrenees we find that the current strain pattern in the western alps combines e w extension and right lateral shear we confirm a counterclockwise rotation of the adriatic microplate which appears to control the strain pattern along its boundaries in the friuli area the alps and the apennines our results also suggest that the africa eurasia plate motion in the western mediterranean may be 40 50 per cent slower that the nuvel1a plate motion model and rotated 20 30 counterclockwise

historical coseismic surface deformation of fluvial gravel deposits schafberg fault lower rhine graben germany intraplate earthquakes pose a significant seismic hazard in densely populated rift systems like the lower rhine graben in central europe while the locations of most faults in this region are well known constraints on their seismogenic potential and earthquake recurrence are limited in particular the holocene deformation history of active faults remains enigmatic in an exposure excavated across the schafberg fault in the southwestern lower rhine graben south of untermaubach in the epicentral region of the 1756 duren earthquake m l 6 2 we mapped a complex deformation zone in holocene fluvial sediments we document evidence for at least one paleoearthquake that resulted in vertical surface displacement of 1 2 0 2 m the most recent earthquake is constrained to have occurred after 815 ad and we have modeled three possible earthquake scenarios constraining the timing of the latest event coseismic deformation is characterized by vertical offset of sedimentary contacts distributed over a 10 m wide central damage zone faults were identified where they fracture and offset pebbles in the vertically displaced gravel layers and fracture orientation is consistent with the orientation of the schafberg fault this study provides the first constraint on the most recent surface rupturing earthquake on the schafberg fault we cannot rule out that this fault acted as the source of the 1756 duren earthquake our study emphasizes the importance of and the need for paleoseismic studies in this and other intracontinental regions in particular on faults with subtle geomorphic expression that would not typically be recognized as being potentially seismically active our study documents textural features in unconsolidated sediment that formed in response to coseismic rupturing of the underlying bedrock fault we suggest that these features e g abundant oriented transgranular fractures in their context should be added to the list of criteria used to identify a fault as potentially active such information would result in an increase of the number of potentially active faults that contribute to seismic hazards of intracontinental regions

pliocene and lower pleistocene fluvial history of the lower rhine embayment germany examples of the tectonic forcing of river courses abstract the plio pleistocene succession has been studied in the northwestern and southern lower rhine embayment by means of a o petrographical geochemical and palaeomagnetic methods data obtained provide improved insight into the drainage pattern of the study area and give evidence to tectonically driven shifts of river courses in the northwestern part of the region the river rhine changed its course gradually towards the north during late pliocene and lower pleistocene times these shifts were forced by an increase of subsidence rates in the same direction in the southern lower rhine embayment an infilling of the main channel of the latest pliocene rhine river the latter of which is represented by the newly defined obel beds throughout the lower rhine embayment was found in the central part of the tectonic unit of the erft block open cast mine hambach due to subsequent eastward tilting of this tectonic unit the course of the rhine shifted into the same direction new palaeomagnetic results concerning the position of the gauss matuyama boundary at the open cast mine hambach support this concept a geochemical study of fine grained sediments has given evidence to a similar eastward shift of a local river entering the lower rhine embayment from the south during late pliocene times the meuse river entered the lower rhine embayment from the southwest during pliocene times east meuse river probably this course prevailed longer during the early pleistocene than previously thought the advance of this river towards the east during early pleistocene times is probably due to the eastward tilting of the erft block as well

strike slip faulting at thebes gap missouri and illinois implications for new madrid tectonism numerous nne and ne striking strike slip faults and associated normal faults folds and transtensional grabens occur in the thebes gap area of missouri and illinois these structures developed along the northwestern margin of the buried reelfoot rift of precambrian cambrian age at the northern edge of the mississippi embayment they have had a long lived and complex structural history this is an area of recent moderate seismicity approximately 45 km north of the new madrid seismic zone stratigraphic evidence suggests that these faults were active during the middle ordovician they were subsequently reactivated between the early devonian and late cretaceous probably in response to both the acadian and ouachita orogenies deformation during this period was characterized by strongly faulted and folded ordovician through devonian rocks in places these deformed rocks are overlain with angular unconformity by undeformed cretaceous strata fault motion is interpreted as dominantly strike slip a still younger period of reactivation involved late cretaceous and cenozoic formations as young as the miocene or pliocene mounds gravel these formations have experienced both minor high angle normal faulting and subsequent major right lateral strike slip faulting en echelon north south folds ene striking normal faults regional fracture patterns and drag folds indicate the right lateral motion for this major episode of faulting which predates deposition of quaternary loess several nondefinitive lines of evidence suggest quaternary faulting similar fault orientations and kinematics as well as recent seismicity and proximity clearly suggest a structural relationship between deformation at thebes gap and tectonism associated with the new madrid area

turbulent flow and sand transport over a cobble bed in a laboratory flume abstractimproving the prediction of sand transport downstream of dams requires characterization of the interaction between turbulent flow and near surface interstitial sands the advanced age and impending decommissioning of many dams have brought increased attention to the fate of sediments stored in reservoirs sands can be reintroduced to coarse substrates that have available pore space resulting from periods of sediment starved flow the roughness and porosity of the coarse substrate are both affected by sand elevation relative to the coarse substrate therefore the turbulence characteristics and sediment transport over and through these beds are significantly altered after sediment is reintroduced past work by the writers on flow over sand filled gravel beds revealed that the fine sediment level controls the volume of material available for transport and the area of sediment exposed to the flow the present work expands on the gravel bed experiments by conducting similar measurements of turbulent f

uncharted seismic risk the potential for earthquakes along the plate boundaries has been mapped with reasonable success our attention should now focus on the threat posed by unanticipated quakes located in the continental interiors

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

a constant slip rate for the western qilian shan frontal thrust during the last 200 ka consistent with gps derived and geological shortening rates abstract active thrust faulting at the front of the qilian shan accommodates the northeastward growth of the tibetan plateau however the lifespan of individual faults and their slip history on different timescales remain largely unknown here we show that the main range bounding thrust fault of the western qilian shan has accrued tectonic slip at an almost constant rate during the last 200 ka and possibly since fault initiation in the mid miocene our finding is based on 10be ages from a flight of five deformed fluvial terraces along the hongshuiba river which constrain the vertical slip rate of the qilian shan frontal thrust to be 1 2 0 1 m ka during the last 200 ka with a fault dip of 30 5 constrained by seismic reflection data we obtain a horizontal shortening rate of 2 0 0 3 m ka this value is consistent with both the short term shortening rate of 1 7 0 3 mm a derived from gps data and the long term shortening rate of 2 1 0 4 m ka which is based on a balanced geological cross section the latter provides a total shortening estimate of 25 3 km since the thrust fault initiated 12 2 ma ago the agreement between the shortening rates on the range of timescales between 100 and 107 years suggests that the western qilian shan frontal thrust has slipped at a steady rate since its initiation and implies that this fault is the main structure responsible for the growth of the western qilian shan

temporal variations in latest quaternary slip across the australian pacific plate boundary northeastern south island new zealand rates of latest quaternary slip from stream terraces and moraines displaced by faults of the alpine shear system in ne south island new zealand vary in space and time detailed histories of fault slip are obtained from combining displacement data with estimates of the age of the surface from weathering characteristics precision in surface ages is 5 20 using rock weathering rinds and 15 50 using soil properties the oldest surfaces examined are 15 20 ka and have right lateral fault offsets up to 400 600 m the main faults of the in the ne south island the wairau awatere clarence hope kekerengu and porters pass faults have average latest quaternary right lateral slip rates of 3 10 5 10 7 10 25 40 5 7 and 3 4 mm yr respectively every fault has undergone a substantial decrease in lateral slip rate in the last 3 5 kyr summed across the plate boundary the average latest quaternary slip rates are comparable to long term rates of horizontal slip across the australian pacific plate boundary around 40 mm yr parallel to the boundary and rates of geodetic strain and seismic moment release over the last 50 100 years approximately the same however sums of lateral fault slip rates over the interval from 15 to 5 ka exceed the plate motions whereas late holocene lateral fault slip rates are less than half the long term average the best explanation of these variations is slip across the plate boundary is episodic varying over perhaps 5 kyr intervals this implies that 15 20 kyr is the time interval necessary to average out shorter 5 kyr episodic variations in plate boundary motions

lithospheric memory state of stress and rheology neotectonic controls on europe s intraplate continental topography abstract to date research on neotectonics and related continental topography development has mostly focused on active plate boundaries characterized by generally high deformation rates the intraplate sedimentary basins and rifts of the northern alpine foreland are associated with a much higher level of neotectonic activity than hitherto assumed seismicity and stress indicator data combined with geodetic and geomorphologic observations demonstrate that europe s intraplate lithosphere is being actively deformed this has major implications for the assessment of its natural hazards and environmental degradation the lithosphere of the northern alpine foreland has undergone a polyphase evolution with an intense interplay between upper mantle thermal perturbations and stress induced intraplate deformation that points to the importance of lithospheric folding of the thermally weakened lithosphere in this paper we address relationships between deeper lithospheric processes neotectonics and surface processes in the northern alpine foreland with special emphasis on tectonically induced topography the objectives are to quantify the effects of ongoing alpine collision and atlantic ridge push on the intraplate deformation in europe and its impact on topography evolution and related natural hazards this paper reviews the four dimensional topographic evolution of the european lithosphere through a multi disciplinary approach linking geology geophysics and geotechnology until now research on neotectonics and related topography development of intraplate regions has received little attention our study examines a number of selected natural laboratories in continental europe from orogen through platform to continental margin these natural laboratories include the carpathians pannonian system the northwest european platform iberia and the atlantic continental margin we focus on lithosphere memory and neotectonics with special attention to the thermo mechanical structure of the lithosphere mechanisms of large scale intraplate deformation late neogene anomalies in subsidence and uplift and links with surface processes and topography evolution

displacement history and slip rate on the reelfoot fault of the new madrid seismic zone abstract a displacement history and slip rates were determined for the reelfoot fault in the new madrid seismic zone from a seismic reflection profile and trench data based on calculations from the seismic reflection line the average slip rate over the last 80 million years is 0 0009 mm year 1 slip rate during the late cretaceous was 0 0007 mm year 1 0 002 mm year 1 during the paleocene midway group 0 001 mm year 1 during paleocene eocene wilcox formation time 0 0003 mm year 1 during the post wilcox pre holocene period and a holocene slip rate of 1 8 mm year 1 based on trench data slip rate on the reelfoot fault has been 4 4 mm year 1 over the last 2400 years and a maximum of 6 2 mm year 1 during the two most recent earthquake cycles between ad 900 and ad 1812 the holocene slip rate is at least four orders of magnitude higher than the average late cretaceous and cenozoic slip rates for the reelfoot fault it would appear that there has been a quaternary change in the stress field in the central united states or the reelfoot fault is experiencing a short lived burst of seismic activity

seismic reflection images of shallow faulting northernmost mississippi embayment north of the new madrid seismic zone high resolution seismic reflection surveys document tectonic faults that displace pleistocene and older strata just beyond the northeast termination of the new madrid seismic zone at the northernmost extent of the mississippi embayment these faults which are part of the fluorspar area fault complex in southeastern illinois are directly in line with the northeast trending seismic zone the reflection data were acquired using an elastic weight drop source recorded to 500 msec by a 48 geophone array 24 fold with a 10 ft 3 0 m station interval recognizable reflections were recorded to about 200 msec 100 150 m the effects of multiple reflections numerous diffractions low apparent velocity i e steeply dipping noise and the relatively low frequency content of the recorded signal provided challenges for data processing and interpreting subtle fault offsets data processing steps that were critical to the detection of faults included residual statics post stack migration deconvolution and noise reduction filtering seismic migration was crucial for detecting and mitigating complex fault related diffraction patterns which produced an apparent folding of reflectors on unmigrated sections detected individual offsets of shallow reflectors range from 5 to 10 m for the top of paleozoic bedrock and younger strata the migrated sections generally indicate vertical to steeply dipping normal and reverse faults which in places outline small horsts and or grabens tilting or folding of stratal reflectors associated with faulting is also locally observed at one site the observed faulting is superimposed over a prominent antiformal structure which may itself be a product of the quaternary deformation that produced the steep normal and reverse faults our results suggest that faulting of the paleozoic bedrock and younger sediments of the northern mississippi embayment is more pervasive and less localized than previously thought

geometry numerical models and revised slip rate for the reelfoot fault and trishear fault propagation fold new madrid seismic zone abstract the geometry and structural relief of late holocene sediments folded across the reelfoot scarp are characterized with trench excavations shallow borings a digital elevation model dem of topography and reelfoot lake rl bathymetry results suggest the scarp forms by heterogeneous shear in the forelimb of a fault propagation fold seismic data and the accompanying structural analysis support the argument that the reelfoot fault does not offset the surface and that the reelfoot scarp is a fold limb structural relief measured across the reelfoot scarp is slightly higher than previous determinations and varies from 7 to 11 m along the western shoreline of rl numerical models based on trishear kinematics constrain growth of the reelfoot monocline and indicate that the underlying reelfoot thrust fault is steeply dipping the shallowest portion of the central reelfoot thrust segment dips 75 where the fault tip has propagated upward from 911 m to its current location 465 m beneath the surface the models indicate that the shallowest section of the southern thrust segment in the reelfoot thrust system dips even more steeply at 80 but has propagated upward only a few tens of meters to its present location 1016 m beneath the surface the thrust is flatter at deeper levels based on the location of earthquake hypocenters strain across the reelfoot scarp is partitioned into two or three separate fold scarps that collectively record a late holocene fault slip rate of 3 9 0 1 mm yr the slip rate is based on 9 m of structural relief the 2290 60 ybp age of folded sediment and a 75 dip for the fault this implies a rate of horizontal contraction in the seismic zone of 1 0 mm yr this rate is strongly dependent on the dip of the thrust calculated by the structural analysis the numerical models argue for reactivation of faults that previously offset paleozoic strata

the impact of coarse grain protrusion on near bed hydrodynamics in steep rivers sediment is often transported over immobile cobbles and boulders previous studies of such conditions have observed that the entrainment rate of the mobile sediment strongly depends on the level of protrusion of the immobile grains here experiments are conducted in a laboratory flume in order to quantify how different levels of protrusion of large aggregates above a fixed fine sediment bed modeled as a patch of hemispheres modify the local hydrodynamics near the fine sediment bed five protrusion levels defined by p k r 0 20 40 60 80 were investigated where k is the protrusion height and r the radius for small protrusion p 20 enhanced shear stress and turbulence intensity on the fine sediment bed is observed as the mixing layer generated at the hemisphere top impacts the fine sediment bed moreover sweep events generated near the top of the hemispheres reach the fine sediment bed for large protrusions p 60 the mixing layer generated near the top of the hemispheres does not reach the fine grains with the consequence that the shear stress drops the remaining turbulence near the fine sediment bed although enhanced by the wakes generated by the hemispherical caps is quasi isotropic the transition between these two distinct near bed flow regimes is found to be around p 40 corresponding to the protrusion levels observed by grams and wilcock 2014 https doi org 10 1002 2013jf002925 above which the erosion of fine sediment ceases

transport of fine sediment over a coarse immobile riverbed sediment transport in cobble boulder rivers consists mostly of fine sediment moving over a coarse immobile bed transport rate depends on several interrelated factors boundary shear stress the grain size and volume of fine sediment and the configuration of fine sediment into interstitial deposits and bed forms existing models do not incorporate all of these factors approaches that partition stress face a daunting challenge because most of the boundary shear is exerted on immobile grains we present an alternative approach that divides the bed into sand patches and interstitial deposits and is well constrained by two clear end member cases full sand cover and absence of sand entrainment from sand patches is a function of their aerial coverage entrainment from interstices among immobile grains is a function of sand elevation relative to the size of the immobile grains the bed sand coverage function is used to predict the ratio of the rate of entrainment from a partially covered bed to the rate of entrainment from a completely sand covered bed which is determined using a standard sand transport model we implement the bed sand coverage function in a morphodynamic routing model and test it against observations of sand bed elevation and suspended sand concentration for conditions of nonuniform fine sediment transport in a large flume with steady uniform flow over immobile hemispheres the results suggest that this approach may provide a simple and robust method for predicting the transport and migration of fine sediment through rivers with coarse immobile beds

effect on flow structure of sand deposition on a gravel bed results from a two dimensional flume experiment 1 particle imaging velocimetry piv was used to quantify the entire two dimensional flow field over a series of fixed test beds in a laboratory flume the test beds used in the experiments provide a two dimensional representation of gravel beds with contrasting roughness the two dimensional form of the beds combined with the nonintrusive nature of piv allowed the velocity field to be quantified right down to the bed surface the three beds used were designed to simulate the progressive effect of sand deposition on a gravel bed with median grain size d50 of 25 mm such a situation is common in bimodal beds but as compared with gravel and sand cases little work has been done to investigate the interaction between the variable roughness of a bimodal bed and the flow structure above it the results demonstrate that as the effective roughness decreases the reverse flow often found in the lee of gravel particles is eliminated furthermore near bed velocities increase while shear stress and turbulent kinetic energy decrease turbulent properties are also diminished higher up in the profile although this is not the case for the mean downstream velocity which remains unaffected except at the bed quadrant analysis reveals that q2 and q4 events become less frequent around high points as effective roughness decreases all these responses to the changing bed conditions are most pronounced in areas where the effective roughness height h approaches 10 mm or less h d50 0 4 such a situation is often found immediately upstream of gravel sand transitions in natural rivers it is hypothesized that the hydraulic response outlined here provides a detailed physically based explanation for the gravel sand transition the combination of reduced bed shear stress and q2 q4 events around gravel particles will result in greater mobility of the sand fraction relative to gravel these experiments thus appear to demonstrate that there is a fundamental threshold between gravel bed and sand bed states that has not previously been quantified

apparent late quaternary fault slip rate increase in the southern lower rhine graben central europe in regions of low strain long earthquake recurrence intervals 104 106 yrs and erosive processes limit preservation of quaternary markers suitable for distinguishing whether faults slip at uniform or secularly varying rates the lower rhine graben in the border region of germany the netherlands and belgium provides a unique opportunity to explore quaternary slip rate variations in a region of low strain using the basal 2 29 0 29 ma and surface 700 80 ka contacts of the regionally extensive main terrace hauptterrasse deposited by the rhine and maas rivers these surfaces are vertically offset 3 140 m and 0 68 m respectively across individual fault strands within a distributed network of northwest trending slow slipping 80 of the sites record an apparent increase in slip rate for the more recent interval from 700 ka to present which corresponds to a period of increased uplift of the nearby rhenish massif and regional volcanism however the apparent increase in slip rate could result in part from erosion of the footwall surface below the main terrace leading to an apparent displacement that is smaller than the total vertical offset since the start of the quaternary prior work focused on characterization of these faults as seismic sources in the lower rhine graben has preferentially relied on the average fault slip rate constrained using the base of the main terrace we suggest that average fault slip rates calculated using the 700 ka main terrace surface are subjected to fewer uncertainties and sample a time interval that is more relevant for seismic hazard analysis electronic supplement 1 table of main terrace surface and basal contact offset measurements figure describing an unrealistic faulting scenario and a kml file with the fault trace mapping spanning the lower rhine graben 1 http www bssaonline org lookup suppl doi 10 1785 0120160197 dc1

late weichselian and holocene earthquake events along the geleen fault in ne belgium osl age constraints abstract in 2005 a trench was opened for palaeoseismological analysis near the village of rotem maas valley ne belgium the trench exposed the geleen fault a branch of the feldbiss fault zone of the lower rhine graben system the latter is one of the most active tectonic structures in nw europe north of the alps the sedimentary record in the trench mainly consists of a sequence of fluvio aeolian and aeolian deposits initially interpreted as late weichselian coversands a gravel pavement interpreted as a regional deflation horizon subdivides the succession into two main parts and the uppermost sediments are overprinted by soil formation processes detailed mapping of the trench walls revealed evidence for two surface rupturing earthquakes we report on the application of quartz based single aliquot optical dating to establish a chronological framework for the sediments and to constrain the timing of the two palaeoearthquakes the optical ages constrain the age of the most recent surface rupturing event between 2 5 0 3 and 3 1 0 3 ka a time interval which is independently supported by 14c ages the penultimate large earthquake occurred just before the formation of the gravel pavement the age of this pavement and thus of the second palaeoearthquake is bracketed between 15 9 1 1 and 18 2 1 3 ka the optical ages allow correlating the sedimentary succession observed at rotem with the coversand stratigraphy as established in the southern netherlands the age of the pebbly deflation horizon indicates that it formed synchronously with the beuningen gravel bed while the immediately under and overlying sediments are correlated with the top of the older coversand i and the base of the older coversand ii units respectively the upper part of the coversands on the upthrown side of the fault are dated at 6 ka which is interpreted as an age underestimation owing to bioturbation the sediments which were originally interpreted as their stratigraphic equivalent on the downthrown side are reliably dated at 6 9 0 7 ka however the grain size characteristics of this deposit differ from those of coversands and rather resemble those of overlying colluvium the origin of this deposit remains enigmatic it might testify to either an as yet unknown holocene phase of colluviation or a third palaeoearthquake for which no evidence was found in the field

an example of neotectonism in a continental interior thebes gap midcontinent united states abstract some of the most intense neotectonic activity known in the continental interior of north america has been recently discovered on a fault zone in the thebes gap area missouri and illinois this faulting almost assuredly was accompanied by large earthquakes the zone is located approximately 30 km north of the new madrid seismic zone and consists of complex north northeast to northeast striking steeply dipping faults that have had a long lived history of reactivation throughout most of the phanerozoic geophysical studies by others suggest that the faults are rooted in the deeply buried late proterozoic and early cambrian reelfoot rift system quaternary deposits are cut by at least four episodes of faulting two of which occurred during the holocene the overall style of neotectonic deformation is interpreted as right lateral strike slip faulting at many locations however near surface displacements have stepped from one fault strand to another and produced normal and oblique slip faults in areas of transtension and high angle reverse faults thrust faults and folds in areas of transpression there is evidence of reactivation of some near surface fault segments during the great 1811 1812 new madrid earthquakes quaternary faulting at thebes gap demonstrates that there are additional seismic source zones in the midcontinent u s other than new madrid and that even in the absence of plate margin orogenesis intense neotectonic activity does occur over long time periods along crustal weaknesses in continental interiors

paleoerosion rates from cosmogenic 10be in a 1 3 ma terrace sequence response of the river meuse to changes in climate and rock uplift abstract river borne quartz carries a cosmogenic nuclide memory that is a function of the catchment wide erosion rate this record may be preserved in fluvial deposits such as river terraces if the age of a terrace is independently known and transport time in the river system is relatively short then the upstream erosion rate at the time of terrace deposition can be determined we have used cosmogenic nuclides to date river terraces in the lower meuse catchment the netherlands and to obtain a 1 3 ma record of paleoerosion rates in a 104 km2 drainage basin comprising the ardennes mountains paleoerosion rates were uniform within the range of 25 35 mm ka from 1 3 to 0 7 ma after 0 7 ma erosion rates have increased progressively to late pleistocene values of around 80 mm ka around 0 7 ma both climatic and tectonic boundary conditions changed the amplitude and duration of climate cycles increased significantly resulting in long periods of sustained low temperatures in the meuse catchment in additio

the earthquake potential of the new madrid seismic zone the fault system responsible for new madrid seismicity has generated temporally clustered very large earthquakes in a d 900 100 years and a d 1450 150 years as well as in 1811 1812 given the uncertainties in dating liquefaction features the time between the past three new madrid events may be as short as 200 years and as long as 800 years with an average of 500 years this advance in understanding the late holocene history of the new madrid seismic zone and thus the contemporary tectonic behavior of the associated fault system was made through studies of hundreds of earthquake induced liquefaction features at more than 250 sites across the new madrid region we have found evidence that prehistoric sand blows like those that formed during the 1811 1812 earthquakes are probably com pound structures resulting from multiple earthquakes closely clustered in time or earthquake sequences from the spatial distribution and size of sand blows and their sedimentary units we infer the source zones and estimate the magnitudes of earth quakes within each sequence and thereby characterize the detailed behavior of the fault system it appears that fault rupture was complex and that the central branch of the seismic zone produced very large earthquakes during the a d 900 and a d 1450 events as well as in 1811 1812 on the basis of a minimum recurrence rate of 200 years we are now entering the period during which the next 1811 1812 type event could occur

paleoseismicity of two historically quiescent faults in australia implications for fault behavior in stable continental regions paleoseismic studies of two historically aseismic quaternary faults in australia confirm that cratonic faults in stable continental regions scr typically have a long term behavior characterized by episodes of activity separated by quiescent intervals of at least 10 000 and commonly 100 000 years or more studies of the approximately 30 km long roopena fault in south australia and the approximately 30 km long hyden fault in western australia document multiple quaternary surface faulting events that are unevenly spaced in time the episodic clustering of events on cratonic scr faults may be related to temporal fluctuations of fault zone fluid pore pressures in a volume of strained crust the long term slip rate on cratonic scr faults is extremely low so the geomorphic expression of many cratonic scr faults is subtle and scarps may be difficult to detect because they are poorly preserved both the roopena and hyden faults are in areas of limited or no significant seismicity these and other faults that we have studied indicate that many potentially hazardous scr faults cannot be recognized solely on the basis of instrumental data or historical earthquakes although cratonic scr faults may appear to be nonhazardous because they have been historically aseismic those that are favorably oriented for movement in the current stress field can and have produced unexpected damaging earthquakes paleoseismic studies of modern and prehistoric scr faulting events provide the basis for understanding of the long term behavior of these faults and ultimately contribute to better seismic hazard assessments

long range and long term fault interactions in southern california paleoseismological data suggest the occurrence of four bursts of seismic moment release in the los angeles region during the past 12 000 yr the historic period appears to be part of an ongoing lull that has persisted for about the past 1000 yr these periods of rapid seismic displacement in the los angeles region have occurred during the lulls between similar bursts of activity observed on the eastern california shear zone in the mojave desert which is now seismically active a kinematic model in which the faults of the greater san andreas system suppress activity on faults in the eastern california shear zone and vice versa can explain the apparent switching of activity between the two fault networks combined with the observation that short term geodetic and longer term geologic rates co vary on major southern california fault systems this suggests that either 1 a temporal cluster of seismic displacements on upper crustal faults increases ductile deformation on their downward extensions or 2 rapid ductile slip in the lower crust beneath faults loads the upper crust driving a seismic cluster we suggest that alternating periods of rapid seismic displacement may be the expected mode of seismicity when two fault systems accommodate the same plate boundary motion and slip on one system suppresses slip on the other

faulted terrace risers place new constraints on the late quaternary slip rate for the central altyn tagh fault northwest tibet the active left lateral altyn tagh fault defines the northwestern margin of the tibetan plateau in western china to clarify late quaternary temporal and spatial variations in slip rate along the central portion of this fault system 85 90 e we have more than doubled the number of dated offset markers along the central altyn tagh fault in particular we determined offset age relations for seven left laterally faulted terrace risers at three sites kelutelage yukuang and keke qiapu spanning a 140 km long fault reach by integrating surficial geologic mapping topographic surveys total station and tripod light detection and ranging t lidar and geochronology radiocarbon dating of organic samples 230 th u dating of pedogenic carbonate coatings on buried clasts and terrestrial cosmogenic radionuclide exposure age dating applied to quartz rich gravels at kelutelage which is the westernmost site 37 72 n 86 67 e two faulted terrace risers are offset 58 3 m and 48 4 m and formed at 6 2 6 1 ka and 5 9 3 7 ka respectively at the yukuang site 38 00 n 87 87 e four faulted terrace risers are offset 92 12 m 68 6 m 55 13 m and 59 9 m and formed at 24 2 9 5 ka 6 4 5 0 ka 5 1 3 9 ka and 24 2 6 4 ka respectively at the easternmost site keke qiapu 38 08 n 88 12 e a faulted terrace riser is offset 33 6 m and has an age of 17 1 2 2 ka the displacement age relationships derived from these markers can be satisfied by an approximately uniform slip rate of 8 12 mm yr however additional analysis is required to test how much temporal variability in slip rate is permitted by this data set

extreme multi millennial slip rate variations on the garlock fault california strain super cycles potentially time variable fault strength and implications for system level earthquake occurrence abstract pronounced variations in fault slip rate revealed by new measurements along the garlock fault have basic implications for understanding how faults store and release strain energy in large earthquakes specifically dating of a series of 26 0 3 5 2 5 m fault offsets with a newly developed infrared stimulated luminescence method shows that the fault was slipping at 14 0 2 2 1 8 mm yr approximately twice as fast as the long term average rate during a previously documented cluster of four earthquakes 0 5 2 0 ka this elevated late holocene rate must be balanced by periods of slow or no slip such as that during the ca 3300 yr long seismic lull preceding the cluster moreover whereas a comparison of paleoseismic data and stress modeling results suggests that individual garlock earthquakes may be triggered by periods of rapid san andreas fault slip or very large slip events the on off behavior of the garlock suggests a longer term mechanism that may involve changes in the rate of elastic strain accumulation on the fault over millennial time scales this inference is consistent with most models of the geodetic velocity field which yield slip deficit rates that are much slower than the average latest pleistocene early holocene post 8 13 ka garlock slip rate of 6 5 1 5 mm yr these observations indicate the occurrence of millennia long strain super cycles on the garlock fault that may be associated with temporal changes in elastic strain accumulation rate which may in turn be controlled by variations in relative strength of the various faults in the garlock san andreas eastern california shear zone fault system and or changes in relative plate motion rates

a model of composite seismic sources for the lower rhine graben northwest europe abstract the lower rhine graben lrg straddling the border zone of belgium the netherlands and germany is an active tectonic structure in continental northwest europe it is characterized by northwest southeast oriented normal faults and moderate but rather continuous seismic activity many faults have been mapped in the lrg but so far a model of fault hierarchy or fault segmentation has been lacking in the frame of a european database of seismogenic sources we have devised a seismic source model for the lrg consisting of so called composite seismic sources each composite seismic source may encompass one or more segments but it is unlikely that a segment would extend across more than one source we distinguish 15 seismic sources based on major stepovers bifurcations gaps and important changes in strike dip direction or slip rate the sources are partitioned into one or more informal fault sections each with an associated surface trace for each source we describe the limits and the composing fault sections and present the geological arguments for their existence we have compiled all relevant data concerning the seismic source parameters required for the database putting lower and upper bounds on strike dip rake slip rate and depth and an upper bound on earthquake magnitude this source model should provide a new basis for modeling seismic hazard as well as for guiding further paleoseismic studies in the lrg online material detailed maps of the composite sources in the lower rhine graben 3d views of the fault model and a table with parameters of earthquake focal mechanisms and detailed information sheets for each composite seismic source

late quaternary activity of the feldbiss fault zone roer valley rift system the netherlands based on displaced fluvial terrace fragments abstract the meuse river crosses the feldbiss fault zone one of the main border fault zones of the roer valley graben in the southern part of the netherlands uplift of the area south of the feldbiss fault zone forced the meuse river to incise and as a result a flight of terraces was formed faults of the feldbiss fault zone have displaced the middle and late pleistocene terrace deposits in this study an extensive geomorphological survey was carried out to locate the faults of the feldbiss fault zone and to determine the displacement history of terrace deposits the feldbiss fault zone is characterized by an average displacement rate of 0 041 0 047 mm a 1 during the late pleistocene individual faults show an average displacement rate ranging between 0 010 and 0 034 mm a 1 the spatial variation in displacement rates along the individual faults reveals a system of overstepping faults these normal faults developed by reactivation of paleozoic strike slip faults as fault displacements at the bases of the younger terrace deposits are apparently similar to the tops of the adjacent older terrace the age of these horizons is the same within thousands of years this implies that the model of terrace development by rapid fluvial incision followed by slow aggradation does apply for this area

reconciling short recurrence intervals with minor deformation in the new madrid seismic zone at least three great earthquakes occurred in the new madrid seismic zone in 1811 and 1812 estimates of present day strain rates suggest that such events may have a repeat time of 1000 years or less paleoseismological data also indicate that earthquakes large enough to cause soil liquefaction have occurred several times in the past 5000 years however pervasive crustal deformation expected from such a high frequency of large earthquakes is not observed this suggests that the seismic zone is a young feature possibly as young as several tens of thousands of years old and no more than a few million years old

application of uav photography to refining the slip rate on the pyramid lake fault zone nevada the pyramid lake fault zone plfz is a 50 km long active northwest trending right lateral fault in the northern walker lane located 30 km east of reno nevada previous paleoearthquake and slip rate studies report that the pyramid lake fault has produced four surface rupturing paleoearthquakes since 15 475 720 cal b p three of which occurred after 8980 260 cal b p and has had an average minimum slip rate of 2 6 0 3 mm yr since the late pleistocene these observations imply that coseismic offset for each paleoearthquake averaged 7 9 m larger than expected from empirical scaling relationships for a strike slip fault of its length to reconcile this discrepancy we used a small camera mounted unmanned aerial vehicle to develop high resolution digital elevation models and interpret previously unreported right laterally offset geomorphic features along the northern section of the plfz offset measurements at seven sites range from 8 to 21 m the ages of displaced features are interpreted from previous lake level and mapping studies of lake lahontan from these observations slip rate estimates at the sites range between 0 5 and 1 6 mm yr these lower values of slip rate require that coseismic displacements associated with previously reported paleoearthquakes average only 3 5 m within the range that would be predicted from empirical scaling relationships of rupture length and coseismic displacement

temporal changes in rock uplift rates of folds in the foreland of the tian shan and the pamir from geodetic and geologic data understanding the evolution of continental deformation zones relies on quantifying spatial and temporal changes in deformation rates of tectonic structures along the eastern boundary of the pamir tian shan collision zone we constrain secular variations of rock uplift rates for a series of five quaternary detachment and fault related folds from their initiation to the modern day when combined with gps data decomposition of interferometric synthetic aperture radar time series constrains the spatial pattern of surface and rock uplift on the folds deforming at decadal rates of 1 5 mm yr these data confirm the previously proposed basinward propagation of structures during the quaternary by fitting our geodetic rates and previously published geologic uplift rates with piecewise linear functions we find that gradual rate changes over 100 kyr can explain the interferometric synthetic aperture radar observations where changes in average uplift rates are greater than 1 mm yr among different time intervals 10 10 and 10 years