a scaling law for slow earthquakes with the availability of the global positioning system and other technical advances a growing number of unusual earthquake phenomena occurring at relatively long periods have been recognized they include deep episodic tremor low frequency earthquakes slow slip events and silent earthquakes based on data chiefly from western japan ide et al report that these slow seismic events follow a unified scaling relationship that clearly differentiates their behaviour from that of regular earthquakes a diverse array of unusual earthquake phenomena occurring at relatively long periods slow events follow a unified scaling relationship that clearly differentiates their behaviour from that of regular earthquakes indicating that they comprise a new earthquake category recently a series of unusual earthquake phenomena have been discovered including deep episodic tremor1 low frequency earthquakes2 very low frequency earthquakes3 slow slip events4 and silent earthquakes5 6 7 8 9 each of these has been demonstrated to arise from shear slip just as do regular earthquakes but with longer characteristic durations and radiating much less seismic energy here we show that these slow events follow a simple unified scaling relationship that clearly differentiates their behaviour from that of regular earthquakes we find that their seismic moment is proportional to the characteristic duration and their moment rate function is constant with a spectral high frequency decay of f 1 this scaling and spectral behaviour demonstrates that they can be thought of as different manifestations of the same phenomena and that they comprise a new earthquake category the observed scale dependence of rupture velocity for these events can be explained by either a constant low stress drop model or a diffusional constant slip model this new scaling law unifies a diverse class of slow seismic events and may lead to a better understanding of the plate subduction process and large earthquake generation

dating the quaternary progress in luminescence dating of sediments abstract luminescence dating comprises a collection of numerical age techniques that are among the most significant chronological tools currently used in quaternary research this paper briefly reviews the key historical developments in luminescence dating from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight exposed sediments we describe the principles and practicalities of the various techniques commonly used in luminescence dating including multiple aliquot single aliquot and single grain procedures and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation e g by means of component analysis and dose distribution methods in optical dating the overview also introduces the other papers in this special issue of quaternary science reviews which address a selection of important issues in basic research technique development and application of luminescence dating to critical questions in the geological and archaeological sciences illustrated with examples from around the world and the last million years of earth history

shallow creep on the haiyuan fault gansu china revealed by sar interferometry interferometric synthetic aperture radar data are used to map the interseismic velocity field along the haiyuan fault system hfs at the north eastern boundary of the tibetan plateau two m 8 earthquakes ruptured the hfs in 1920 and 1927 but its 260 km long central section known as the tianzhu seismic gap remains unbroken since 1000 years the envisat sar data spanning the 2003 2009 period cover about 200 300 km2 along three descending and two ascending tracks interferograms are processed using an adapted version of roi pac the signal due to stratified atmospheric phase delay is empirically corrected together with orbital residuals mean line of sight velocity maps are computed using a constrained time series analysis after selection of interferograms with low atmospheric noise these maps show a dominant left lateral motion across the hfs and reveal a narrow 35 km long zone of high velocity gradient across the fault in between the tianzhu gap and the 1920 rupture we model the observed velocity field using a discretized fault creeping at shallow depth and a least squares inversion the inferred shallow slip rate distribution reveals aseismic slip in between two fully locked segments the average creep rate is 5 mm yr 1 comparable in magnitude with the estimated loading rate at depth suggesting no strain accumulation on this segment the modeled creep rate locally exceeds the long term rate reaching 8 mm yr 1 suggesting transient creep episodes the present study emphasizes the need for continuous monitoring of the surface velocity in the vicinity of major seismic gaps in terms of seismic hazard assessment

carbon mineralization and oxygen dynamics in sediments with deep oxygen penetration lake superior to understand carbon and oxygen dynamics in sediments with deep oxygen penetration we investigated eight locations 160 318 m depth throughout lake superior despite the 2 4 weight percent organic carbon content oxygen penetrated into the sediment by 3 5 to 12 cm at all locations such deep penetration is explained by low sedimentation rates 0 01 0 04 cm yr 21 high solubility of oxygen in freshwater and a shallow 2 cm bioturbation zone in response mainly to oxygen variations in the bottom waters the sediment oxygen penetration varied seasonally by as much as several centimeters suggesting that temporal variability in deeply oxygenated sediments may be greater than previously acknowledged the oxygen uptake rates 4 4 7 7 mmol m 22 d 21 average 6 1 mmol m 22 d 21 and carbon mineralization efficiency 90 of deposited carbon were similar to those in marine hemipelagic and pelagic sediments of comparable sedimentation rates the reactivity of organic carbon was found to decrease with age similarly to the power law documented in marine environments the burial flux of carbon into the deep sediment 0 7 mmol m 22 d 21 was 2 5 of the previously estimated primary production maximum volume specific carbon degradation rates were 0 3 1 5mmol cm 23 d 21 bioturbation coefficient near the sediment surface was 3 8 cm 2 yr 21 these results indicate that carbon cycling in large freshwater systems conforms

shallow creep along the 1999 izmit earthquake rupture turkey from gps and high temporal resolution interferometric synthetic aperture radar data 2011 2017 characterizing the spatiotemporal evolution of creep is essential to constrain fault slip budget and understand creep mechanism studies based on interferometric synthetic aperture radar and global positioning system gps satellite observations until 2012 have shown that the central segment of the 17 august 1999 mw 7 4 izmit earthquake on the north anatolian fault began slipping aseismically following the event in the present study we combine new interferometric synthetic aperture radar time series based on terrasar x and sentinel 1a b radar images acquired over the period 2011 2017 with near field gps measurement campaigns performed every 6 months from 2014 to 2016 the mean velocity fields reveal that creep on the central segment of the 1999 izmit fault rupture continues to decay more than 19 years after the earthquake in overall agreement with models of postseismic afterslip decaying logarithmically with time for a long period of time along the fault section that experienced supershear velocity rupture during the izmit earthquake creep continues with a rate up to 8 mm year a significant transient accelerating creep is detected in december 2016 on the sentinel 1 time series near the maximum creep rate location associated with a total surface slip of 10 mm released in 1 month only additional analyses of the vertical velocity fields show a persistent subsidence on the hanging wall block of the golcuk normal fault that also ruptured during the izmit earthquake our results demonstrate that afterslip processes along the north anatolian fault east southeast of istanbul are more complex than previously proposed as they vary spatiotemporally along the fault

along strike variations of the partitioning of convergence across the haiyuan fault system detected by insar oblique convergence across tibet leads to slip partitioning with the coexistence of strike slip normal and thrust motion on major fault systems a key point is to understand and model how faults interact and accumulate strain at depth here we extract ground deformation across the haiyuan fault restraining bend at the northeastern boundary of the tibetan plateau from envisat radar data spanning the 2001 textendash2011 period we show that the complexity of the surface displacement field can be explained by the partitioning of a uniform deep seated convergence mountains and sand dunes in the study area make the radar data processing challenging and require the latest developments in processing procedures for synthetic aperture radar interferometry the processing strategy is based on a small baseline approach before unwrapping we correct for atmospheric phase delays from global atmospheric models and digital elevation model errors a series of filtering steps is applied to improve the signal to noise ratio across high ranges of the tibetan plateau and the phase unwrapping capability across the fault required for reliable estimate of fault movement we then jointly invert our insar time series together with published gps displacements to test a proposed long term slip partitioning model between the haiyuan and gulang left lateral faults and the qilian shan thrusts we explore the geometry of the fault system at depth and associated slip rates using a bayesian approach and test the consistency of present day geodetic surface displacements with a long term tectonic model we determine a uniform convergence rate of 10 8 6 textendash11 5 mm yr 1 with an n89 81 textendash97 e across the whole fault system with a variable partitioning west and east of a major extensional fault jog the tianzhu pull apart basin our 2 d model of two profiles perpendicular to the fault system gives a quantitative understanding of how crustal deformation is accommodated by the various branches of this thrust strike slip fault system and demonstrates how the geometry of the haiyuan fault system controls the partitioning of the deep secular motion

slip along the hayward fault california estimated from space based synthetic aperture radar interferometry for 3 5 years following the 1989 m 7 1 loma prieta earthquake creep along the southern hayward fault california slowed or ceased slip apparently resumed pre earthquake rates by 1994 except for a locked 3 km long segment at the southern fault tip which had consistently slipped at 9 mm yr before 1989 we use repeated interferometric synthetic aperture radar intsar measurements to map active deformation along the hayward fault while slip rates recovered between 1992 and 1995 if pure strike slip is assumed then the slip rates estimated from intsar range changes between 1992 and 1995 are generally consistent with creepmeter and alignment array measurements along much of the fault and confirm the temporary locking of the southernmost fault segment however along 6 km of the fremont segment intsar slip estimates appear to be at least twice those measured in the field transient vertical slip northeast side up of 2 3 mm yr near the southern tip of the creep patch could explain this observation first order boundary element models of a vertical frictionless fault in an elastic half space predict some but not all of the inferred vertical slip

geochemical controls on internal phosphorus loading in lake of the woods abstract sediment phosphorus p diagenesis and release in polymictic systems are poorly understood here we determine the mechanistic controls on the processes that drive p release from the sediments in lake of the woods low the vertical distributions of the relevant diagenetic parameters including oxygen ph redox potential dissolved p iron fe and other metals in the porewater were measured and the fluxes of dissolved oxygen and p across the sediment water interface swi at the four locations in low were quantified we characterized solid p speciation and analyzed the iron and corresponding metal contents in five sediment p binding forms short term diffusive fluxes of p ranged between 0 3 and 7 8 mg m 2d 1 controlled by the mineralization of freshly deposited organic matter and the redox sensitive iron cycle long term net p release rates were between 0 21 and 9 96 mg m 2d 1 controlled by the diagenetic remineralization of p binding pools which regulates long term sediment p releases hypoxia may have led to the release of previously stored fe p in the sediments which has likely increased internal p loading for a timescale that is longer than seasonal while fe sorbed phosphorus is the major barrier for p release in the surface sediments p is immobilized in deep sediments via the formation of calcium ca p aluminum al p and possibly vivianite our study demonstrates the importance of sediments as sources of the productivity limiting nutrient phosphorus reveals the geochemical controls on sediment p release and helps further the understanding of how sediments regulate water quality and affect eutrophication and the possibility of algal blooms

postglacial left slip rate and past occurrence of m 8 earthquakes on the western haiyuan fault gansu china high resolution hr air photographs and a 1 m horizontal and 2 m vertical resolution digital elevation model derived from them by stereophotogrammetry provide new constraints on the behavior of the western stretch of the active haiyuan fault in gansu province china the photographs cover three swaths along the fault each about 2 km long and at least 500 m wide near the village of songshan at 103 5oe this high resolution data set is used to map and measure cumulative horizontal offsets of alluvial terraces and risers that range between 115 and la 135 m and 70 and 90 m at two sites dating these terraces with 14c yields minimum and maximum ages of 8400 and 7600 and 14 200 years b p respectively this leads to a postglacial slip rate of 12 4 mm yr with a most likely minimum value of 11 6 1 1 mm yr the smallest stream offsets observed on the hr photographs range between 8 and 16 m and are interpreted as coseismic displacements of the last few earthquakes with m 8 that ruptured the 220 km long tianzhu gap of the fault west of the yellow river earthquakes of that size within this gap which has been quiescent for at least 800 years would recur at intervals of 1050 450 years

thirty five year creep rates for the creeping segment of the san andreas fault and the effects of the 2004 parkfield earthquake constraints from alignment arrays continuous global positioning system and creepmeters we present results from differential global positioning system gps surveys of seven alignment arrays and four continuous gps sites along the creeping segment of the san andreas fault surveys of four alignment arrays from the central creeping segment yield 33 to 36 year average minimum slip rates of 21 26 mm yr these rates are consistent with previous alignment array surveys spanning a 10 year period and with rates determined by creepmeters indicating approximate steady state creep along the central creeping segment for at least 35 years motion between continuous gps sites that span the central creeping segment is 28 2 0 5 mm yr for two sites that are 1 km apart and 33 6 1 mm yr for two sites that are 70 km apart slip rates therefore increase with distance from the creeping segment of the san andreas fault all rates reported here are significantly slower than the 39 2 mm yr rate predicted for motion between the sierra nevada great valley block and the pacific plate repeat surveys of three alignment arrays following the 2004 parkfield earthquake demonstrate that its coseismic and short term postseismic offsets decrease rapidly with distance from the epicenter from 150 mm to 15 mm to 5 mm at respective distances of 9 36 and 54 km to the northwest continuous gps data confirm that little coseismic and postseismic slip occurred along the central creeping segment geodetic and geologic slip rates are compared and different models for the accommodation of transcurrent deformation across the creeping segment are discussed

roughness of fault surfaces over nine decades of length scales 1 we report on the topographic roughness measurements of five exhumed faults and thirteen surface earthquake ruptures over a large range of scales from 50 m to 50 km we used three scanner devices lidar laser profilometer white light interferometer spanning complementary scale ranges from 50 m to 10 m to measure the 3 d topography of the same objects i e five exhumed slip surfaces vuache sillingy bolu corona heights dixie valley magnola a consistent geometrical property i e self affinity emerges as the morphology of the slip surfaces shows at first order a linear behavior on a log log plot where axes are fault roughness and spatial length scale covering five decades of length scales the observed fault roughness is scale dependent with an anisotropic self affine behavior described by four parameters two power law exponents h constant among all the faults studied but slightly anisotropic h 0 58 0 07 in the slip direction and h 0 81 0 04 perpendicular to it and two pre factors showing variability over the faults studied for larger scales between 200 m and 50 km we have analyzed the 2 d roughness of the surface rupture of thirteen major continental earthquakes these ruptures show geometrical properties consistent with the slip perpendicular behavior of the smaller scale measurements our analysis suggests that the inherent non alignment between the exposed traces and the along or normal slip direction results in sampling the slip perpendicular geometry although a data gap exists between the scanned fault scarps and rupture traces the measurements are consistent within the error bars with a single geometrical description i e consistent dimensionality over nine decades of length scales

imbricated slip rate processes during slow slip transients imaged by low frequency earthquakes low frequency earthquakes lfes often occur in conjunction with transient strain episodes or slow slip events sses in subduction zones their focal mechanism and location consistent with shear failure on the plate interface argue for a model where lfes are discrete dynamic ruptures in an otherwise slowly slipping interface sses are mostly observed by surface geodetic instruments with limited resolution and it is likely that only the largest ones are detected the time synchronization of lfes and sses suggests that we could use the recorded lfes to constrain the evolution of sses and notably of the geodetically undetected small ones however inferring slow slip rate from the temporal evolution of lfe activity is complicated by the strong temporal clustering of lfes here we apply dedicated statistical tools to retrieve the temporal evolution of sse slip rates from the time history of lfe occurrences in two subduction zones mexico and cascadia and in the deep portion of the san andreas fault at parkfield we find temporal characteristics of lfes that are similar across these three different regions the longer term episodic slip transients present in these datasets show a slip rate decay with time after the passage of the sse front possibly as t 1 4 they are composed of multiple short term transients with steeper slip rate decay as t with between 1 4 and 2 we also find that the maximum slip rate of sses has a continuous distribution our results indicate that creeping faults host intermittent deformation at various scales resulting from the imbricated occurrence of numerous slow slip events of various amplitudes

the burst like behavior of aseismic slip on a rough fault the creeping section of the haiyuan fault china recent observations suggesting the influence of creep on earthquakes nucleation and arrest are strong incentives to investigate the physical mechanisms controlling how active faults slip we focus here on deriving generic characteristics of shallow creep along the haiyuan fault a major strike slip fault in china by investigating the relationship between fault slip and geometry we use optical images and time series of synthetic aperture radar data to map the surface fault trace and the spatiotemporal distribution of surface slip along the creeping section of the haiyuan fault the fault trace roughness shows a power law behavior similar to that of the aseismic slip distribution with a 0 8 roughness exponent typical of a self affine regime one possible interpretation is that fault geometry controls to some extent the distribution of aseismic slip as it has been shown previously for coseismic slip along active faults creep is characterized by local fluctuations in rates that we define as creep bursts the potency of creep bursts follows a power law behavior similar to the gutenberg richter earthquake distribution whereas the distribution of bursts velocity is non gaussian suggesting an avalanche like behavior of these slip events such similarities with earthquakes and lab experiments lead us to interpret the rich dynamics of creep bursts observed along the haiyuan fault as resulting from long range elastic interactions within the heterogeneous earth s crust

under the hood of the earthquake machine toward predictive modeling of the seismic cycle advances in observational laboratory and modeling techniques open the way to the development of physical models of the seismic cycle with potentially predictive power to explore that possibility we developed an integrative and fully dynamic model of the parkfield segment of the san andreas fault the model succeeds in reproducing a realistic earthquake sequence of irregular moment magnitude m w 6 0 main shocks including events similar to the ones in 1966 and 2004 and provides an excellent match for the detailed interseismic coseismic and postseismic observations collected along this fault during the most recent earthquake cycle such calibrated physical models provide new ways to assess seismic hazards and forecast seismicity response to perturbations of natural or anthropogenic origins

fast late pleistocene slip rate on the leng long ling segment of the haiyuan fault qinghai china 1 fieldwork along the western haiyuan fault where it cuts young glacial landforms in the leng long ling range qinghai northeastern tibet yields new constraints on its long term left slip rate our mapping near 101 85 e based on aerial photographs 1 50 000 topographic maps and spot images shows glacial valley edges and lateral moraines offset 200 m by the fault quartz rich cobbles were sampled on top of one moraine for in situ 10be and 26al cosmogenic nuclide dating among 12 dated samples the 6 oldest show ages clustering at 10 300 339 years this age probably reflects the time of last reshaping of the moraine before the valley glacier withdrew south of the fault around the end of the younger dryas 11 000 years b p assuming that the 200 40 m moraine offset started to be recorded after glacial retreat across the fault constrains the late pleistocene slip rate on the leng long ling segment of the haiyuan fault to be 19 5 mm yr

multiphase flow of the late wisconsinan cordilleran ice sheet in western canada in central british columbia ice flow during the late wisconsinan fraser glaciation ca 25 10 ka occurred in three phases the ice expansion phase occurred during an extended period when glaciers flowed westward to the pacific ocean and east southeastward onto the nechako plateau from ice centers in the skeena hazelton coast and omineca mountains initially glacier flow was confined by topography along major valleys but eventually piedmont and montane glaciers coalesced to form an integrated glacier system the cordilleran ice sheet in the maximum phase a cordilleran ice divide developed over the nechako plateau to 300 km inland from the pacific coast at this time the surface of the ice sheet extended well above 2500 m above sea level and flowed westward over the skeena hazelton and coast mountains onto the continental shelf and eastward across the rocky mountains into alberta in the late glacial phase a rapid rise of the equilibrium line caused ice lobes to stagnate in valleys and restricted accumulation centers to high mountains discordant directions in ice flow are attributed to fluctuations of the ice divide representing changes in the location of accumulation centers and ice thickness ice centers probably shifted in response to climate irregular growth in the ice sheet rapid calving ice streaming and drainage of proglacial and subglacial water bodies crosscutting ice flow indicators and preservation of early valley parallel flow features in areas exposed to later cross valley glacier erosion indicate that the ice expansion phase was the most erosive and protracted event

spatial and temporal variations in creep rate along the el pilar fault at the caribbean south american plate boundary venezuela from insar in eastern venezuela the caribbean south american plate boundary follows the el pilar fault system previous studies based on three gps campaigns 2003 2005 2013 demonstrated that the el pilar fault accommodates the whole relative displacement between the two tectonic plates 20 mm yr and proposed that 50 60 of the slip is aseismic jouanne et al 2011 reinoza et al 2015 in order to quantify the possible variations of the aseismic creep in time and space we conducted an insar time series analysis using the nsbas method on 18 images from the alos 1 satellite spanning the 2007 2011 period during this 3 5 year period insar observations show that aseismic slip decreases eastwards along the fault the creep rate of the western segment reaches 25 3 9 4 mm yr on average compared to 13 4 6 9 mm yr on average for the eastern segment this is interpreted through slip distribution models as being related to coupled and un coupled areas between the surface and ca 20 km in depth insar observations also show significant temporal creep rate variations accelerations during the considered time span along the western segment the transient behavior of the creep is not consistent with typical postseismic afterslip following the 1997 ms 6 8 earthquake the creep is thus interpreted as persistent aseismic slip during an interseismic period which have a pulse or transient like behavior

creep and quakes on the northern transition zone of the san andreas fault from gps and insar data 1 the san juan bautista sjb segment forms the northern transition zone of the creeping section of the san andreas fault it is an area of moderate seismicity the largest instrumentally recorded earthquakes have been m5 5 however historic records suggest six m 6 earthquakes occurred near the sjb segment between 1840 and 1899 it is also an area that has experienced several slow earthquakes we perform a joint inversion of gps and insar data to determine the current rate and distribution of interseismic creep we find two low slip locked segments at mid seismogenic depths that may represent source regions for the 19th century earthquakes we find that the sjb segment is currently accumulating strain energy at the rate of one m6 3 6 7 earthquake per century at this rate the 1840 1899 sequence released 135 510 years of accumulated moment deficit

millennial recurrence of large earthquakes on the haiyuan fault near songshan gansu province china the haiyuan fault is a major active left lateral fault along the northeast edge of the tibet qinghai plateau studying this fault is important in understanding current deformation of the plateau and the mechanics of continental deformation in general previous studies have mostly focused on the slip rate of the fault paleo seismic investigations on the fault are sparse and have been targeted mostly at the stretch of the fault that ruptured in the 1920 m 8 6 earthquake in ningxia province to investigate the millennial seismic history of the western haiyuan fault we opened two trenches in a small pull apart basin near songshan in gansu province the excavation exposes sedimentary layers of alternating colors dark brown silty to clayey deposit and light yellowish brown layers of coarser grained sandy deposit the main fault zone is readily recognizable by the disruption and tilting of the layers six paleoseismic events are identified and named ss1 through ss6 from youngest to oldest charcoal is abundant yet generally tiny in the shallowest parts of the trench exposures thirteen samples were dated to constrain the ages of paleoseismic events all six events have occurred during the past 3500 3900 years the horizontal offsets associated with these events are poorly known however events ss3 to ss6 appear to be large ones judging from comparison of vertical separations and widths of fault zones the youngest event ss1 instead seems to be a minor one probably the 1990 mw 5 8 earthquake thus four large events in 3500 3900 years would imply a re currence interval of about 1000 years three events ss2 to ss4 prior to 1990 occurred sometime during 1440 1640 a d shortly after 890 1000 a d and 0 410 a d re spectively we tentatively associate them with the 1514 a d 1092 a d and 143 or 374 a d historical earthquakes taking 10 2 m of slip for large events ss3 and ss4 comparable to the 1920 m 8 haiyuan earthquake their occurrence times would be consistent with the long term 12 4 mm yr estimate of lasserre et al 1999 however a more realistic evaluation of slip rate and its possible change with time requires a more rigorous determination of coseismic slip amounts of past earth quakes

creep burst coincident with faulting in marble observed in 4 d synchrotron x ray imaging triaxial compression experiments faults in carbonate rocks show both seismic and aseismic deformation processes leading to a wide range of slip velocities we deformed two centimeter scale cores of carrara marble at 25 c und

roughness of natural fault surfaces the roughness of fault surfaces is important in the mechanics of fault slip and could play a role in determining whether sliding occurs via earthquakes or fault creep we have made preliminary measurements of the power spectral density of several fault surfaces over the wavelength range from 10 5 to 1 m using field and laboratory scale profilimeters the fault surfaces are strongly anisotropic profiles parallel to the slip direction have amplitudes about one order of magnitude lower than those perpendicular to the slip direction over most of the wavelength interval measured fault roughness perpendicular to the slip direction is similar to the roughness of natural joints the greater smoothness in the slip direction presumably represents wear resulting from slip combining our data with previous measurements of the roughness spectrum of the san andreas fault shows that fault surfaces are fractal over nearly eleven orders of magnitude in wavelength

precise location of san andreas fault tremors near cholame california using seismometer clusters slip on the deep extension of the fault 1 we examine a 24 hour period of active san andreas fault saf tremor and show that this tremor is largely composed of repeated similar events utilizing this similarity we locate the subset of the tremor with waveforms similar to an identified low frequency earthquake lfe master template located using p and s wave arrivals to be 26 km deep to compensate for low signal to noise we estimate event pair differential times at clusters of nearby stations rather than at single stations we find that the locations form a near linear structure in map view striking parallel to the saf and near the surface trace therefore we suggest that at least a portion of the tremor occurs on the deep extension of the fault likely reflecting shear slip similar to subduction zone tremor if so the saf may extend to the base of the crust 10 km below the deepest regular earthquakes on the fault

seismic velocity change patterns along the san jacinto fault zone following the 2010 m7 2 el mayor cucapah and m5 4 collins valley earthquakes

crustal deformation in the india eurasia collision zone from 25 years of gps measurements the india eurasia collision zone is the largest deforming region on the planet direct measurements of present day deformation from global positioning system gps have the potential to discriminate between competing models of continental tectonics but the increasing spatial resolution and accuracy of observations have only led to increasingly complex realizations of competing models here we present the most complete accurate and up to date velocity field for india eurasia available comprising 2576 velocities measured during 1991 2015 the core of our velocity field is from the crustal movement observation network of china i ii 27 continuous stations observed since 1999 56 campaign stations observed annually during 1998 2007 1000 campaign stations observed in 1999 2001 2004 and 2007 260 continuous stations operating since late 2010 and 2000 campaign stations observed in 2009 2011 2013 and 2015 we process these data and combine the solutions in a consistent reference frame with stations from the global strain rate model compilation then invert for continuous velocity and strain rate fields we update geodetic slip rates for the major faults some vary along strike and find that those along the major tibetan strike slip faults are in good agreement with recent geological estimates the velocity field shows several large undeforming areas strain focused around some major faults areas of diffuse strain and dilation of the high plateau we suggest that a new generation of dynamic models incorporating strength variations and strain weakening mechanisms is required to explain the key observations seismic hazard in much of the region is elevated not just near the major faults

sedimentary phosphorus dynamics and the evolution of bottom water hypoxia a coupled benthic pelagic model of a coastal system the present study examines oxygen and phosphorus dynamics at a seasonally hypoxic site in the arkona basin of the baltic sea a coupled benthic pelagic reactive transport model is used to describe the evolution of bottomwater solute concentrations as well as pore water and sediment profiles aerobic respiration dominates remineralization with iron reduction denitrification and sulphate reduction playing secondary roles while other pathways are negligible sediments represent a significant oxygen sink chiefly due to the aerobic degradation of organic matter as well as nitrification and iron oxyhydroxide precipitation most phosphorus deposited in sediments is in organic matter yet cycling is dominated by iron bound phosphorus due to rapid dissimilatory iron reduction coupled with aerobic iron oxyhydroxide formation sustained hypoxia results in an initial decrease in sediment phosphorus content due to dissolution of phosphorus bearing iron oxyhydroxides resulting in a pulse of phosphate to overlying waters although an organic rich layer is formed under low oxygen conditions enhanced remineralization of organic phosphorus relative to organic carbon tempers sedimentary phosphorus accumulation upon reoxygenation of bottom waters after a decade of sustained hypoxia oxygen concentrations do not immediately achieve values observed prior to hypoxia because the organic rich layer creates a higher benthic oxygen demand artificial reoxygenation of bottom waters leads to a substantial increase in the ironbound phosphorus pool the total phosphorus content of the sediment however is unaffected a relapse into hypoxia would consequently produce a large pulse of phosphate to the overlying waters potentially exacerbating the situation

partitioning of oblique convergence coupled to the fault locking behavior of fold and thrust belts evidence from the qilian shan northeastern tibetan plateau oblique plate convergence is common but it is not clear how the obliquity is achieved by continental fold and thrust belts we address this problem in the qilian shan northeastern tibetan plateau using fieldwork observations geomorphic analysis and elastic dislocation modeling of published geodetic data a thrust dips ssw from the northern range front and underlies steeper thrusts in the interior cenozoic thrust related shortening across the qilian shan is 155 175 km based on two transects elastic dislocation modeling indicates that horizontal strain in the interseismic period is consistent with oblique slip on a single low angle detachment thrust below 26 km depth dipping ssw at 17o we suggest this detachment is located above north china block crust originally underthrust during paleozoic orogeny horizontal shear strain is localized directly above the up dip limit of creep on the detachment and is coincident with the left lateral haiyuan fault this configuration implies oblique slip on the detachment below seismogenic depths is partitioned in the shallow crust onto separate strike slip and thrust faults this is consistent with strain partitioning in oceanic subduction zones but has not previously been found by dislocation models of continental interiors the marginal strike slip altyn tagh fault influences thrusting within the qilian shan for 100 200 km from the fault but does not control the regional structure where paleozoic basement faults have been reactivated the qilian shan resembles the main tibetan plateau in nascent form active thrusts are marginal to an interior that is developing plateau characteristics involving low relief and low seismicity

coseismic deformation of the 2001 mw 7 8 kokoxili earthquake in tibet measured by synthetic aperture radar interferometry the 14 november 2001 m w 7 8 kokoxili earthquake ruptured more than 400 km of the westernmost stretch of the left lateral kunlun fault in northern tibet interferometric synthetic aperture radar data from descending orbits along four adjacent tracks covering almost the entire rupture and 1 m pixel ikonos satellite images are used to map the rupture geometry and the surface displacements produced by the event interferograms are then inverted to solve for coseismic slip on the fault at depth the radar data show that the rupture connected the heituo fault where the earthquake initiated to the main kunlun fault cutting across a pull apart trough in between the two strike slip faults the fault model includes two vertical sections extending to a depth of 20 km and discretized into 5 km 5 km patches using a nonnegative least squares method that includes an appropriate degree of smoothing we solve for the left lateral slip on each fault patch our solution shows that the largest slip occurred at depths between 0 and 5 km reaching 8 m in two areas 200 and 250 km east of the earthquake epicenter significant slip took place below 10 km at both ends of the rupture slip appears to have been highly variable along the fault defining six sections of major moment release these sections correspond to six subsegments of the kunlun fault system defined from the surface morphology of the fault this suggests that fault geometry exerted a predominant influence on controlling the rupture propagation

fault slip distribution and fault roughness summary we present analysis of the spatial correlations of seismological slip maps and fault topography roughness illuminating their identical self affine exponent though the complexity of the coseismic spatial slip distribution can be intuitively associated with geometrical or stress heterogeneities along the fault surface this has never been demonstrated based on new measurements of fault surface topography and on statistical analyses of kinematic inversions of slip maps we propose a model which quantitatively characterizes the link between slip distribution and fault surface roughness our approach can be divided into two complementary steps i using a numerical computation we estimate the influence of fault roughness on the frictional strength pre stress we model a fault as a rough interface where elastic asperities are squeezed the hurst exponent h characterizing the self affinity of the frictional strength field approaches h h 1 where h is the roughness exponent of the fault surface in the direction of slip ii using a quasi static model of fault propagation which includes the effect of long range elastic interactions and spatial correlations in the frictional strength the spatial slip correlation is observed to scale as hs h 1 where hs represents the hurst exponent of the slip distribution under the assumption that the origin of the spatial fluctuations in frictional strength along faults is the elastic squeeze of fault asperities we show that self affine geometrical properties of fault surface roughness control slip correlations and that hs h given that h 0 6 for a wide range of faults various accumulated displacement host rock and slip movement we predict that hs 0 6 even if our quasi static fault model is more relevant for creeping faults the spatial slip correlations observed are consistent with those of seismological slip maps a consequence is that the self affinity property of slip roughness may be explained by fault geometry without considering dynamical effects produced during an earthquake

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

deglacial changes in ocean circulation from an extended radiocarbon calibration temporal variations in the atmospheric concentration of radiocarbon sometimes result in radiocarbon based age estimates of biogenic material that do not agree with true calendar age this problem is particularly severe beyond the limit of the high resolution radiocarbon calibration based on tree ring data which stretches back only to1 2 about 11 8 kyr before present bp near the termination of the younger dryas cold period if a wide range of palaeoclimate records are to be exploited for better understanding the rates and patterns of environmental change during the last deglaciation extending the well calibrated radiocarbon timescale back further in time is crucial several studies attempting such an extension using uranium thorium dated corals3 4 5 and laminae counts in varved sediments6 7 8 9 show conflicting results here we use radiocarbon data from varved sediments in the cariaco basin in the southern caribbean sea to construct an accurate and continuous radiocarbon calibration for the period 9 to 14 5 kyr bp nearly 3 000 years beyond the tree ring based calibration a simple model compared to the calculated atmospheric radiocarbon concentration and palaeoclimate data from the same sediment core suggests that north atlantic deep water formation shut down during the younger dryas period but was gradually replaced by an alternative mode of convection possibly via the formation of north atlantic intermediate water

measurement of interseismic strain across the haiyuan fault gansu china by insar the haiyuan fault is part of a major left lateral fault system at the northeastern edge of the tibet qinghai plateau two m8 earthquakes 1920 and 1927 occurred along the fault bracketing an unbroken section of the fault identified as the tianzhu seismic gap we use interferometric synthetic aperture radar data from descending orbits of the ers satellites acquired between 1993 and 1998 along two adjacent tracks covering the gap to measure the current surface movements and better understand the present day mechanical behavior of this fault section the analysis of the radar data involves first the combined correction of orbital errors and errors associated with the phase delay through the troposphere a subset of the data is then selected based on the analysis of the residual noise spectra for each pair of data the selected interferograms are stacked and the average phase change rate is converted in fault parallel velocity assuming that the ground movement is horizontal and parallel to the fault velocity maps from both tracks show a zone of high velocity gradient across the fault a few kilometers wide consistent with left lateral slip on the haiyuan fault the average velocity field from the two tracks in their overlapping area is well fit with a single screw dislocation model in an elastic half space the derived fault slip rate at depth 4 2 8 mm yr is consistent with recent gps results the corresponding shallow apparent locking depth 0 4 2 km can be explained by a current low stress accumulation on the fault due to creep almost on the entire fault plane however unless it is transient this creep would be paradoxical with the occurrence of past large earthquakes along this fault section as revealed by paleoseismology an alternative model implying both shallow creep in the brittle upper crust and deep aseismic slip beneath the seismogenic layer separated by a locked section would be consistent with insar observations and with the potential for large earthquakes on the fault as well a two dislocation model with slip at 5 mm yr beneath 15 km and a transient creep rate of 11 mm yr between 2 and 7 km fits the insar data however the width and creep rate of the shallow creeping zone and their possible along strike variations are still poorly resolved with the present data set

the 14 november 2001 kokoxili tibet earthquake high frequency seismic radiation originating from the transitions between sub rayleigh and supershear rupture velocity regimes seismic array based analysis of the major kokoxili earthquake tibet 14 november 2001 yields an unambiguous reconstruction of the seismic rupture history and relates it to the generated seismic radiation we demonstrate that after a classical sub rayleigh velocity stage the rupture speed has jumped to supershear values close to compressional wave velocity over a 175 km long fault segment before abruptly slowing down in the late part of the earthquake the transition locations between these three phases are correlated with the fault geometry and are associated with the most energetic radiation this observation proves that the rupture velocity changes as theoretically predicted are a primary source of high frequency seismic radiation this result requires reconsidering the origins of seismic damage generally attributed to slip variations

the implications of fault zone transformation on aseismic creep example of the north anatolian fault turkey aseismic creep is observed at surface along several segments of the north anatolian right lateral active fault in turkey a major plate boundary between eurasia and anatolia identifying the mechanisms that control creep and their temporal and spatial change represents a major challenge for predicting the mechanical evolution of active faults the interplay between creep and earthquakes and the link between short term observations from geodesy and the long term fault zone evolution we combine geological observations laboratory analyses and imaging techniques shedding new light on the mechanism of fault creep along the north anatolian fault naf and its time dependent change a clear correlation is shown between shallow creep and near surface fault gouge composition locked segments of the naf are mostly composed of massive limestones without clay gouges whereas creeping segments comprise clay gouges that contain low friction minerals such fault gouges appear to result from a progressive change of initial volcanic host rocks during their deformation anastomosing cleavage develops during the first stage of displacement leading to layering oblique at first and then subparallel to the fault which accommodates part of the aseismic creep by pressure solution soluble minerals are dissolved leading to passive concentration of phyllosilicates in the gouges where alteration transformations by fluid flow produce low friction minerals at the same time damage zones are fractured and fractures are sealed by carbonates as a result these mineralogical and structural transformations weaken the gouge and strengthen the damage zone leading to the change from diffuse to localized seismic aseismic zones

interseismic and postseismic shallow creep of the north qaidam thrust faults detected with a multitemporal insar analysis understanding the mechanisms by which earthquake cycles produce folding and accommodate shortening is essential to quantify the seismic potential of active faults and integrate aseismic slip within our understanding of the physical mechanisms of the long term deformation however measuring such small deformation signals in mountainous areas is challenging with current space geodesy techniques due to the low rates of motion relative to the amplitude of the noise here we successfully carry out a multitemporal interferometric synthetic aperture radar analysis over the north qaidam fold thrust system in ne tibet where eight mw 5 2 earthquakes occurred between 2003 and 2009 we report various cases of aseismic slip uplifting the thickened crust at short wavelengths we provide a rare example of a steep shallow 13 km long and 6 km wide afterslip signal that coincides spatially with an anticline and that continues into 2011 in response to a mw 6 3 event in 2003 we suggest that a buried seismic slip during the 2003 earthquake has triggered both plastic an elastic folding and aseismic slip on the shallow thrusts we produce a first order two dimensional model of the postseismic surface displacements due to the 2003 earthquake and highlight a segmented slip on three fault patches that steepen approaching the surface this study emphasizes the fundamental role of shallow aseismic slip in the long term and permanent deformation of thrusts and folds and the potential of interferometric synthetic aperture radar for detecting and characterizing the spatiotemporal behavior of aseismic slip over large mountainous regions

an aseismic slip transient on the north anatolian fault constellations of synthetic aperture radar sar satellites with short repeat time acquisitions allow exploration of active faults behavior with unprecedented temporal resolution along the north anatolian fault naf in turkey an 80 km long section has been creeping at least since the 1944 m w 7 3 earthquake near ismetpasa with a current interferometric synthetic aperture radar insar derived average creep rate of 8 3 mm yr i e a third of the naf long term slip rate we use a dense set of sar images acquired by the cosmo skymed constellation to quantify the spatial distribution and temporal evolution of creep over 1 year we identify a major burst of aseismic slip spanning 31 days with a maximum slip of 2 cm between the surface and 4 km depth this result shows that fault creep along this section of the naf does not occur at a steady rate as previously thought highlighting a need to revise our understanding of the underlying fault mechanics

factors controlling long term phosphorus efflux from lake sediments exploratory reactive transport modeling abstract we perform for the first time a global sensitivity analysis on a generic diagenetic reaction transport model rtm to elucidate the effects of environmental thermodynamic and kinetic factors on the magnitudes of phosphorus release fluxes from aquatic sediments under a range of conditions typically found in lake sediments our model includes the processes that describe redox sensitive phosphorus releases the so called classical model and processes by which phosphorus mobilization is affected by porewater sulfate on decadal and longer time scales sediment phosphorus effluxes are primarily determined by sedimentation flux of reactive organic matter sedimentation flux of iron oxyhydroxides concentrations of dissolved oxygen and sulfate at the sediment water interface and the rate at which phosphate is immobilized in reduced sediment we show that the effects of these factors on phosphorus effluxes are interdependent and discuss the mechanisms of such interactions the dominant pathways by which dissolved sulfate increases phosphorus efflux in iron rich hypoxic sediments are discussed in detail in contrast to short term phosphorus releases such as described by the classical model long term phosphorus retention is controlled by phosphorus removal to deep reduced sediment rather than processes at the sediment water interface hence the results of short term laboratory or in situ studies such as sediment incubations experiments cannot be unequivocally extended to long time scales our results provide explanations to the reports that lake restoration measures such as restricting phosphorus inputs to a lake or oxygenating the lake s hypolimneon or both in the long term often fail to decrease sediment phosphorus effluxes the re deposition of sediment substances after their release into the water column the feedback often overlooked in sediment rtms can critically affect the magnitude and dynamics of phosphorus efflux from sediments depending on sediment history the same set of external boundary conditions can generate diagenetic regimes with either high or low phosphorus effluxes bistability

modelling temporal variation of surface creep on the chihshang fault in eastern taiwan with velocity strengthening friction summary the active chihshang fault at the boundary between the eurasian and the philippine sea plates along the longitudinal valley in eastern taiwan is creeping near the surface but has also produced large earthquakes at mid crustal depth such as the 2003 m w 6 5 chengkung earthquake the creep rate measured at the surface shows strong seasonal fluctuations before the chengkung earthquake correlated with groundwater pressure variations measured at nearby wells the chengkung earthquake did not rupture the fault near the surface but induced a sudden increase of creep rate that decayed with time during the postseismic period these observations suggest that the near surface fault obeys a rate strengthening friction law we conduct numerical simulations based upon the observed variations of creep rate with regard to a velocity strengthening friction law and 1 d groundwater diffusion model to investigate the fault rheology behind this phenomenon the model which assumes a creeping fault segment extending from the surface to a depth of 5 km yields a good fit to the creep data when the friction parameters are assumed to vary with depth or to have changed at the time of the chengkung earthquake our best model suggests that the creeping zone is characterized by a rate parameter a log v o f 1 3 10 2 and a friction coefficient of 0 84 and a long term slip rate of 25 9 mm yr 1 at depths less than 87 m by contrast the lower segment of the creeping zone exhibits a much lower friction coefficient of 0 19 a smaller a of 6 6 10 3 and a higher long term slip rate of 38 1 mm yr 1 at depths between 0 087 and 5 0 km this change in rate parameters implies that the lithologies or physical properties of the fault rocks may vary with depth alternatively a model assuming a dramatic increase in rate parameter from 5 6 10 4 to 6 2 10 3 by the strong ground shaking of the chengkung earthquake can also yield a fair agreement with the observed data the lack of a notable deceleration in fault creep rate during the dry period from 2002 to mid 2003 suggests that the real recharging system for the fault zone may be more complicated than what we assumed in this study

constant dimensionality of fault roughness from the scale of micro fractures to the scale of continents 1 many faults and fractures in various natural and man made materials share a remarkable common fractal property in their morphology we report on the roughness of faults in rocks by analyzing the out of plane fluctuations of slip surfaces they display a statistical power law relationship with a nearly constant fractal exponent from millimeter scale micro fractures in fault zones to coastlines measuring thousands of kilometers that have recorded continental breakup a possible origin of this striking fractal relationship over 11 orders of magnitude of length scales is that all faulting processes in rocks share common characteristics that play a crucial role in the shaping of fault surfaces such as the effects of elastic long range stress interactions and stress screening by mechanical heterogeneities during quasi static fracture growth

relation between continental strike slip earthquake segmentation and thickness of the crust 1 high resolution maps of large continental strike slip earthquake surface ruptures show that they are formed of fault segments these segments are bounded by fault bends step overs or combinations of the two the lowest limit in size for such segments may not be relevant in the understanding of earthquake mechanics as it pertains to the granular properties of fault zones the maximum limit in segment length however is important as it is directly relates to the maximum extent of seismic rupture to measure the length of the segments a new quantitative method based on piecewise linear fitting is developed and is used to automatically retrieve segments from earthquake rupture maps next this approach is tested against a set of ten continental strike slip earthquake ruptures derived from similar high quality maps the test suggests that segments have a maximum length of 18 km independent of regional tectonic setting slip inversions for earthquakes based on seismological and or geodetic data most often are not unique and can show some variability even for one particular event some basic characteristics however such as total moment release or general source geometry seem to persist that are relevant to earthquake mechanics measurements of the maximum horizontal extent of individual slip patches derived from seismic source inversion for strike slip ruptures show that their strike dimension does not increase infinitely with magnitude but instead reaches a maximum value of 25 km these two independent lines of observations complemented by earlier data and analog experiments suggest that it is the thickness of the seismogenic crust that controls the structural scaling of the length of seismic segments and that it is independent of the ultimate size of individual earthquakes

spatio temporal evolution of aseismic slip along the haiyuan fault china implications for fault frictional properties article history we use 20 years of synthetic aperture radar acquisitions by the ers and envisat satellites to investigate the spatial and temporal variations of strain rates along the 35 km long creeping section of the haiyuan fault at the north eastern boundary of the tibetan plateau we then use the derived displacements to infer the fault s frictional properties and discuss the relationship between creep and the seismic behavior of the fault located in between a millennial seismic gap and the 1920 m8 surface rupture trace this section has an average creep rate of 5 1m m yr about the interseismic loading rate the comparison of average surface velocity profiles derived from sar interferometry across the creeping section reveals a creep rate increase and or a creep migration to shallower depth between the 1990s and the 2000s we apply a smoothed time series analysis scheme on envisat insar data to investigate the creep rate variations during the 2004 2009 time period our analysis reveals that the creep rate accelerated in 2007 although data resolution does not allow to better constrain the onset of creep acceleration and its amplitude both decadal and short term transient behaviors are coeval with the largest earthquakes m 4 5 along the fault segment in recent years from the precise mapping of the surface fault trace we use the fault strike variations and the mohr circle construction to compute the along strike distribution of the friction coefficient along the creeping segment and compare it with the observed distribution of the creep rate we find that the creep rate scales logarithmically with the friction coefficient in agreement with the rate and state friction law in a rate strengthening regime the estimated value of log v 2 10 3 indicates that the earthquakes occurring along the creeping section cannot be the cause for a significant change in the overall segment s creep rate and that the recorded micro seismicity is most likely creep driven finally given the size and frictional properties of the creeping section we estimate based on previous models of dynamic rupture simulations a 0 20 probability for a rupture to break through this section together with the geometrical configuration of the haiyuan fault these results suggest that the creeping segment may act as a persistent barrier to earthquake propagation

biogeochemical mechanisms controlling phosphorus diagenesis and internal loading in a remediated hard water eutrophic embayment abstract phosphorus p levels in eutrophic lakes with restricted external p inputs often show hysteresis resulting from sediment p diagenetic recycling hard water oxygenated lakes are often thought to be less susceptible to p release from sediment due to precipitation of p with calcium carbonate and p sorption on iron fe oxyhydroxides in oxidized surface sediments however perpetuated eutrophic conditions in many hard water oxygenated lakes persist despite drastic reduction of external p inputs what limits p sediment binding capacity and drives its release from sediments in such lakes is often less understood here we characterize sediment p diagenetic processes driving persistent internal loading in the bay of quinte a hard water polymictic embayment of lake ontario canada we used a multifaceted approach combining a comprehensive three year study of sediment p binding forms recent sediment stratigraphy and accumulation high spatial resolution measurement of dissolved oxygen redox potential and ph across the sediment water interface and depth profiles of nutrient and metals concentrations in pore water despite oxygenated bottom water conditions p diffusive fluxes during summer are substantial 1 6 5 mg p m2 day representing as much as 50 of external p inputs estimated rates of benthic organic carbon degradation indicate that anaerobic organic p mineralization in anoxic sediments is the main driver of p release which is strongly influenced by fe reduction estimated rates of benthic organic carbon degradation indicate that anaerobic organic p mineralization in anoxic sediments is the main driver of p release in surface sediment the redox sensitive p is the prevailing diagenetically reactive p phase emphasizing strong coupling with ferric fe while this indicates substantial p sorption on fe oxyhydroxides their spare binding capacity is limited as reducible fe p ratios are close to sorption limit the calcium carbonate bound p increased with sediment depth at the expense of redox sensitive p suggesting diagenetic sequestration into apatite with sediment burial however only 40 of diagenetically reactive p forms which account for 2 3 of the total p in surface sediment are permanently retained during burial importantly our data show that in fact significant p flux occurs in shallow areas with an apparent discordance with concurrent measures of long term p release from the sediments these results also demonstrate that short term measures cannot be extrapolated to long term estimates and vice versa

evidence for an earthquake barrier model from mw 7 8 kokoxili tibet earthquake slip distribution abstract the slip distribution of the mw 7 8 kokoxili tibet 2001 earthquake has been measured at high resolution using optical correlation of satellite images and provides both the parallel and perpendicular components of the horizontal co seismic slip this reveals a variation of the horizontal slip at a scale of 20 km along strike anti correlation of slip parallel and perpendicular to the fault indicates transfer of slip from the horizontal to the vertical component at the ends of segments these features suggest a rupture model with segments separated by strong persistent geometric barriers the unexpected ending of the rupture south of the main fault can be explain by such a structure but bears important implications for the initiation and rupture directivity of the next earthquake

interplay of seismic and aseismic deformations during earthquake swarms an experimental approach observations of earthquake swarms and slow propagating ruptures on related faults suggest a close relation between the two phenomena earthquakes are the signature of fast unstable ruptures initiated on localized asperities while slow aseismic deformations are experienced on large stable segments of the fault plane the spatial proximity and the temporal coincidence of both fault mechanical responses highlight the variability of fault rheology however the mechanism relating earthquakes and aseismic processes is still elusive due to the difficulty of imaging these phenomena of large spatiotemporal variability at depth here we present laboratory experiments that explore in great detail the deformation processes of heterogeneous interfaces in the brittle creep regime we track the evolution of an interfacial crack over 7 orders of magnitude in time and 5 orders of magnitude in space using optical and acoustic sensors we explore the response of the system to slow transient loads and show that slow deformation episodes are systematically accompanied by acoustic emissions due to local fracture energy disorder features of acoustic emission activities and deformation rate distributions of our experimental system are similar to those in natural faults on the basis of an activation energy model we link our results to the rate and state friction model and suggest an active role of local creep deformation in driving the seismic activity of earthquake swarms

episodic creep events on the san andreas fault caused by pore pressure variations recent seismic and geodetic observations indicate that interseismic creep rate varies in both time and space the spatial extent of creep pinpoints locked asperities while its temporary accelerations known as slow slip events may trigger earthquakes although the conditions promoting fault creep are well studied the mechanisms for initiating episodic slow slip events are enigmatic here we investigate surface deformation measured by radar interferometry along the central san andreas fault between 2003 and 2010 to constrain the temporal evolution of creep we show that slow slip events are ensembles of localized creep bursts that aseismically rupture isolated fault compartments using a rate and state friction model we show that effective normal stress is temporally variable on the fault and support this using seismic observations we propose that compaction driven elevated pore fluid pressure in hydraulically isolated fault zone and subsequent frictional dilation cause the observed slow slip episodes we further suggest that the 2004 mw6 parkfield earthquake might have been triggered by a slow slip event which increased the coulomb failure stress by up to 0 45 bar per year this implies that while creeping segments are suggested to act as seismic rupture barriers slow slip events on these zones might promote seismicity on adjacent locked segments

optical dating studies of quaternary organic rich sediments from southwestern british columbia and northwestern washington state the suitability of optical dating using 1 4 ev infrared excitation for determining the time of deposition or compaction of organic rich sediments and peat is assessed with measurements on seven samples from six different lithostratigraphic units one is of zero age two have associated 14c ages three are known to have been deposited during an interglaciation and one is 1 ma old the samples yield satisfactory optical ages ranging from 0 to over 100 ka we conclude that the muir point formation southern vancouver island and the whidbey formation northwestern washington state were both deposited during 18o stage 5 as previously deduced from other evidence the age obtained from the 1 ma sample was significantly too low the optical dating method is simpler and more precise than thermoluminescence dating and is recommended for future work

geochemistry of marine sediments by david j burdige princeton nj princeton university press 2006 609 pages 110 line figures 33 tables 85 00 cloth

are stress distributions along faults the signature of asperity squeeze we propose a possible model for the origin of the spatial fluctuations of the stress field along faults and test our model in the case of the nojima fault japan where unique estimates of the absolute stress field have been obtained the model consists of two parts an up scaling of the fault morphology measured at laboratory scales and a numerical computation using a boundary element approach of the influence on the stress field along the fault of an elastic squeeze of the fault asperities accordingly fluctuations of the stress field along the fault would be dominated by quenched fault properties rather than dynamical stress fluctuations produced during earthquakes

spatial variations in slip deficit on the central san andreas fault from insar summary we use ers insar measurements to record spatial variations in creep rate along the creeping segment of the san andreas fault saf california between 1992 and 2001 inversion of geodetic data yields a slip rate distribution along the creeping segment which is used for firstorder moment release and deficit calculations we present a time averaged spatial picture of surface deformation and associated subsurface creep an interferometric stack is constructed from 12 interferograms that show good coherence for the decade of observation the total right lateral offset spanned by the data is 34 mm yr 1 along most of the length of the creeping segment this offset occurs within a narrow 2 km zone close to the fault trace in the northern part a minor part of the offset is taken up by the nearby calaveras paicines fault in general the observed rates of surface creep are consistent with those obtained by several other studies for a longer and or earlier period of time using different geodetic methods this suggests that the average creep rate has been constant over a period of almost four decades a joint gps insar inversion implies that the shallow creep rate is variable along strike reaching up to 31 5 1m m yr 1 in the central section of the creeping segment tapering off along strike to the south and becoming partitioned across two subparallel faults in the north the deep slip rate beneath the seismogenic layer is 33 3m m yr 1 the difference between shallow and deep slip rates suggests that there is a shallow slip deficit on the creeping segment of the saf csaf moment release rate due to aseismic slip is approximately three orders of magnitude greater than seismic moment release the annual creep on the csaf is equivalent to the moment released in a m 6 earthquake the equivalent moment of the slip deficit relative to the deep slip rate is between 4 1 10 17 and 8 4 10 17 nm yr 1 which is equivalent to a magnitude 5 7 5 9 earthquake over a 150 yr period the deficit is equivalent to a m 7 2 7 4 earthquake this slip deficit may be compensated by intermittent moderate sized events or by accelerated afterslip following large events on nearby fault segments

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

an integrated perspective of the continuum between earthquakes and slow slip phenomena slow slip a mechanism by which faults can relieve stress was thought to be distinct from earthquakes however a global review of slow slip phenomena suggests that instead there is a continuum between the two types of event

quaternary stratigraphy and history of the ootsa lake cheslatta river area nechako plateau central british columbia erosion along the nechako reservoir and cheslatta river spillway has resulted in unusually well exposed late quaternary and holocene stratigraphy surficial sediments in the study area are mostly products of late wisconsinan glaciation however evidence for pre late wisconsinan sedimentation has been found along the shores of the nechako reservoir including till of an older glaciation and organic bearing blue grey lacustrine sediments of probable middle wisconsinan age stratigraphic correlation of the lake sediments suggests that an extensive lake system occurred in the region during the olympia nonglacial interval late wisconsinan ice initially moved along major valleys with glaciofluvial outwash deposited in front of the advancing ice advance phase glaciolacustrine sediments are rare but significant as slope failures are spatially associated with areas where they are preserved the distribution of these sediments and associated deltaic deposits indicates that advance phase glacial lakes occurre

sawtooth segmentation and deformation processes on the southern san andreas fault california five contiguous 12 13 km fault segments form a sawtooth geometry on the south ernmost san andreas fault the kinematic and morphologic properties of each segment depend on fault strike despite differences of strike between segments of as little as 3 degrees oblique slip transpression of fault segments within the indio hills mecca hills and durmid hill results from an inferred 8 1 ratio of dex tral slip to convergence across the fault zone triggered slip and creep are confined almost en tirely to transpressive segments of the fault durmid hill has been formed in the last 28 n 6 ka by uplift at an average rate of 3 1 mm a

strain budget of the ecuador colombia subduction zone a stochastic view the 2016 pedernales earthquake m w 7 8 ruptured a portion of the colombia ecuador subduction interface where several large historical earthquakes have been documented since the great 1906 earthquake m 8 6 considering all significant ruptures that occurred in the region it has been suggested that the cumulative moment generated co seismically along this part of the subduction over the last century exceeds the moment deficit accumulated inter seismically since 1906 such an excess challenges simple models with earthquakes resetting the elastic strain accumulated inter seismically in locked asperities these inferences are however associated with large uncertainties that are generally unknown the impact of spatial smoothing constraints on co seismic and inter seismic models also prevents any robust assessment of the strain budget we propose a bayesian kinematic slip model of the 2016 pedernales earthquake using the most comprehensive dataset to date including insar and gps offsets tsunami waveforms and kinematic records from high rate gps and strong motions in addition we use inter seismic geodetic velocities to produce a probabilistic inter seismic coupling model of the subduction interface our stochastic co seismic and inter seismic solutions include the ensemble of all plausible models consistent with our prior information and that fit the observations within uncertainties the analysis of these model ensembles indicates that an excess of co seismic moment during the 1906 2016 period is likely in central ecuador only if we assume that 1942 and 2016 earthquakes are colocated if this assumption is relaxed we show that this conclusion no longer holds given uncertainties in co and inter seismic processes the comparison of 1942 and 2016 teleseismic records reveals large uncertainties in the location of the 1942 event hampering our ability to draw strong conclusions on the unbalanced moment budget in the region our results also show a heterogeneous coupling of the subduction interface that coincides with two slip asperities in our co seismic model for the 2016 pedernales earthquake and with the location of historical ruptures in 1958 1979 and 1998 the spatial variability in coupling and complexity in earthquake history suggest strong heterogeneities in frictional properties of the subduction megathrust

under pressure clastic dykes in glacial settings abstract clastic dykes are widespread in glacial settings and we provide examples from switzerland patagonia iceland and the antarctic ranging in age from tertiary to recent on the basis of these examples we establish the general characteristics of clastic dykes and proceed to establish the direction of propagation on sedimentological grounds micromorphological analysis reveals that sedimentation in the dykes is ruled by pressure gradients and that ordinary sedimentological rules do not apply clastic dykes act like safety valves in the subglacial hydraulic system their development depends on specific subglacial conditions like water volume and pressure the nature of the bed sediments or bedrock and the hydraulic properties of the bed a number of scenarios for clastic dyke development are presented as there is not just one set of conditions under which they form development of clastic dykes affects glaciodynamics like velocity and surging and landform formation like till thickness and bedrock disruption

late wisconsinan glacial history in the bonaparte lake map area south central british columbia implications for glacial transport and mineral exploration1this article is one of a series of papers published in this special issue on the theme of new insights in cordilleran intermontane geoscience reducing exploration risk in the mountain pine beetle affected area british columbia 2earth sciences sector contribution number 20100093 this study is centred on the bonaparte lake map area located in the southern interior plateau of south central british columbia the reconstruction of the late wisconsinan glacial history of this part of the southern sector of the cordilleran ice sheet incorporates i the analysis and interpretation of landforms of various scales ii the sedimentology and stratigraphy of glacial sediments and iii the geochemical and mineralogical composition of till and analysis of regional glacial dispersal of these components the onset of the last glacial event was initiated by ice advancing westerly and southwesterly into the study area from an alpine source region located in the cariboo mountains as glaciation intensified ice from the coast mountains coalesced with the cariboo mountain ice over the interior plateau and developed into an ice divide around 52 north latitude which resulted in ice flow to be diverted to a southerly direction over the study area the two dominant ice flow directions produced pal

quaternary stratigraphy and glacial history of the peace river valley northeast british columbiathis article is one of a selection of papers published in this special issue on the theme geology of northeastern british columbia and northwestern alberta diamonds shallow gas gravel and glaciers two cordilleran and three laurentide glacial advances are recorded in quaternary sediments and landforms in the peace river valley northeast british columbia the advances are inferred from fluvial gravels glaciolacustrine sedi ments and tills within nested paleovalleys excavated during three interglaciations and from the distribution of granitoid clasts derived from the canadian shield till of the last late wisconsinan laurentide glaciation occurs at the surface ex cept where it is overlain by postglacial sediments the advance that deposited this till was the most extensive in the study area and the only advance definitively recognized in western alberta south of the study area late wisconsinan cordil leran till has not been found in the study area but cordilleran and laurentide ice may have coalesced briefly during the last glaciation support for this supposition is provided by the inferred deflection of laurentide flutings to the southeast by cordilleran ice the earliest laurentide advance may have been the least extensive of the three laurentide events recog nized in the study area erratics attributed to this advance occur only east of the halfway river beatton river drainage divide

origin and diagenesis of polyphosphate in lake sediments a 31pߚnmr study polyphosphate poly p was detected with the use of 31 p nuclear magnetic resonance nmr spectroscopy in sediments from a large variety of lakes with different trophic state and morphometry in the top 0 5 cm of sediment poly p was 1 5 to 11 4 of total p nonreactive phosphorus nrp in the naoh fraction often classified as organically bound phosphate was up to 46 inorganic poly p in some surface sediments the poly p content equalled the iron fixed phosphorus determined by chemical phosphorus fractionation sediments were probably supplied with poly p by sedimentation because there were substantial amounts of poly p in plankton and settling seston as demonstrated with sediments of lake petersdorf benthic organisms can also contribute to the formation of poly p up to 0 11 mg p g dry weight 21 under favorable aerobic conditions poly p is more rapidly transformed into single orthophosphate during diagenesis than other inorganic and organic p species the transformation of organic p compounds and poly p can contribute significantly to the release of p during diagenesis and should be considered along with the reductive dissolution of p sorbed to iron oxihydroxides

advance of alpine glaciers during final retreat of the cordilleran ice sheet in the finlay river area northern british columbia canada abstract sharp crested moraines up to 120 m high and 9 km beyond little ice age glacier limits record a late pleistocene advance of alpine glaciers in the finlay river area in northern british columbia the moraines are regional in extent and record climatic deterioration near the end of the last glaciation several lateral moraines are crosscut by meltwater channels that record downwasting of trunk valley ice of the northern cordilleran ice sheet other lateral moraines merge with ice stagnation deposits in trunk valleys these relationships confirm the interaction of advancing alpine glaciers with the regionally decaying cordilleran ice sheet and verify a late glacial age for the moraines sediment cores were collected from eight lakes dammed by the moraines two tephras occur in basal sediments of five lakes demonstrating that the moraines are the same age plant macrofossils from sediment cores provide a minimum limiting age of 10 550 10 250 cal yr bp 9230 50 14c yr bp for abandonment of the moraines the advance that left the moraines may date to the younger dryas period the finlay moraines demonstrate that the timing and style of regional deglaciation was important in determining the magnitude of late glacial glacier advances

quaternary geology of the babine porphyry copper district implications for geochemical exploration the quaternary stratigraphy of the babine lake region is characterized by a late wisconsinan succession of advance phase glaciolacustrine sediments glaciofluvial deposits and till pollen data from a rare new interglacial site suggest a colder than present middle wisconsinan climate ice flow during the last glaciation was dominantly southeasterly but in the babine range a regional westerly ice flow event occurred evidence for westerly flow diminishes eastward of babine lake suggesting that the valley was near the eastward limit of an interior ice divide deglacial sediments include ice marginal debris flow glaciofluvial and glaciolacustrine sediments raised delta elevations indicate that glacial lake babine extended nearly 150 m above present lake level to 850 m asl and higher earlier phases may have existed locally a variety of holocene deposits cap the quaternary succession glaciation has important implications for exploration in this copper producing area southeasterly glacial dispersal patterns dominate despite a regionally complex ice flow history highly anomalous concentrations of copper occur in tills down ice of most known bedrock copper occurrences and a number of similarly anomalous till sites with no known copper sources have been identified in drift covered areas exploration problems due to the thick and complex surficial cover can be overcome by selective sampling of basal tills the composition of which clearly reflects the presence of buried mineral deposits the effectiveness of till geochemistry as a method for locating buried mineralization in the region will be enhanced by careful selection of sample media and by a clear understanding of the glacial history

fennoscandian palaeoglaciology reconstructed using a glacial geological inversion model the evolution of ice sheet configuration and flow pattern in fennoscandia through the last glacial cycle was reconstructed using a glacial geological inversion model i e a theoretical model that formalises the procedure of using the landform record to reconstruct ice sheets the model uses mapped flow traces and deglacial melt water landforms as well as relative chronologies derived from cross cutting striae and till lineations as input data flow trace systems were classified into four types i time transgressive wet bed deglacial fans ii time transgressive frozen bed deglacial fans iii surge fans and iv synchronous non deglacial event fans using relative chronologies and aggregation of fans into glaciologically plausible patterns a series of ice sheet configurations at different time slices was erected a chronology was constructed through correlation with dated stratigraphical records and proxy data reflecting global ice volume geological evidence exists for several discrete ice sheet configurations centred over the scandinavian mountain range during the early weichselian the build up of the main weichselian fennoscandian ice sheet started at approximately 70 ka and our results indicate that it was characterised by an ice sheet with a centre of mass located over southern norway this configuration had a flow pattern which is poorly reproduced by current numerical models of the fennoscandian ice sheet at the last glacial maximum the main ice divide was located overthe gulf of bothnia a major bend in the ice divide was caused by outflow of ice to the northwest over the lowest part of the scandinavian mountain chain widespread areas of preserved pre late weichselian landscapes indicate that the ice sheet had a frozen bed core area which was only partly diminished in size by inward transgressive wet bed zones during the decay phase

the relationship between seismic and aseismic slip on the philippine fault on leyte island bayesian modeling of fault slip and geothermal subsidence delineating seismic and aseismic slip on faults allows the exploration of the complex relationship between these different modes of slip further quantifying them helps in the assessment of seismogenic potential we present a distributed slip model of the rate of aseismic slip along the leyte island section of the philippine fault and make comparisons with the extent of seismic slip from the latest significant earthquakes in july 2017 we derived both coseismic and aseismic slip distributions from kinematic inversions of synthetic aperture radar interferometric insar observations using a probabilistic bayesian framework velocity maps from stacking and time series analysis of alos interferograms spanning 4 years 2007 2011 show a step change in ground deformation right on the fault inverting for slip at depth reveals along strike variations of aseismic slip rate over 100 km aseismic slip on the surface reaches rates of more than 3 cm yr equivalent to the long term slip rate 3 3 0 2 cm yr over the same period a 20 km segment in tongonan appears to be locked this segment ruptured in mw 6 5 and mw 5 8 earthquakes on 6 and 10 july 2017 respectively as constrained by sentinel 1 and alos 2 insar data seismic slip appears to be restricted within the tongonan segment with up to 152 21 cm of left lateral displacement the slip budget and complementarity between the extents of interseismic and coseismic slip suggest that a seismogenic asperity exists in tongonan the presence of active hydrothermal systems and rate strengthening materials provide physical conditions that can promote aseismic slip

fault slip rates at depth from recurrence intervals of repeating microearthquakes unique attributes in sequences of recurring similar microearthquakes at parkfield california provide a means for inferring slip rate at depth throughout the active fault surface from the time intervals between sequence events application of the method using an 11 year microseismicity record revealed systematic spatial and temporal changes in the slip rate that were synchronous with earthquake activity and other independent measures of fault zone slip if this phenomenon is found to be generally common behavior in active faults it forms the basis for a method to monitor the changing strain field throughout a seismogenic fault zone

quaternary geology of part of the mcleod lake map area nts 093j central british columbia lithostratigraphy glacial history and chronology the coalescence and subsequent divergence of glaciers near the mcleod lake map area during the last fraser glaciation are recorded by landforms ice flow indicators and the distribution of sediments ice initially flowed into the study area from the northwest with at least one fluctuation in the ice front position ice flow during glacial maximum was generally to the northeast and transitioned to the east during deglaciation the quaternary stratigraphic record spans the fraser glaciation and is represented by a sequence of advance glaciolacustrine sediments multiple till units retreat glaciolacustrine and glaciofluvial sediments and associated postglacial aeolian material the surficial geology is dominated by thick streamlined till that thins where relief is high glaciofluvial outwash occurs mostly in northeast and southeast trending meltwater channels while ice contact glaciofluvial deposits and ablation till occur in depressions throughout the region extensive glaciolacustrine deposits bla

stratigraphy and paleoecology of pleistocene interstadial sediments central british columbia abstract two exposures of organic rich interstadial sediments in central british columbia provide information on middle wisconsinan environments and climates near the center of the region subsequently covered by the late wisconsinan cordilleran ice sheet interstadial sediments at bullion pit overlie drift of early wisconsinan or older age and underlie thick drift of late wisconsinan age alluvium or colluvium and peat were deposited on the floor of the ancestral quesnel river valley 46 000 40 000 14 c yr ago when the vegetation consisted of spruce forest with dry openings and local fens and the climate was colder and perhaps drier than today this is broadly consistent with paleoclimatic reconstructions for the same time interval for babine lake 400 km to the northwest and for meadow creek 400 km to the southeast plant rich pond sediments containing tephra layers and vertebrate remains are exposed between two drifts in a ravine at mexican hill 30 km east of quesnel although they may be contemporaneous with the bullion pit beds the nonglacial sediments at mexican hill more likely were deposited sometime after the warmest part of the last interglaciation but prior to 50 000 yr b p at that time the vegetation at mexican hill probably was parkland the present vegetation at mexican hill is boreal forest thus a drier and possibly cooler climate is indicated

late quaternary glacial and interglacial environments of the nechako river cheslatta lake area central british columbia the quaternary stratigraphy of the nechako river cheslatta lake area of central british columbia is de scribed and interpreted to reconstruct the late quaternary history of the region exposures of glacial and nonglacial sediments deposited prior to the last glaciation fraser are limited to three sites pollen assemblages from pre fraser nonglacial sediments at two of these sites reveal forested conditions around 39 000 bp during the advance phase of the fraser glaciation glacial lakes were ponded when trunk glaciers blocked some tributary valleys early in the glaci ation the drainage was free in easterly draining valleys subsequently the easterly drainage was blocked either locally by sediments and ice or as a result of impoundment of the fraser river and its tributaries east of the study area ice generally moved east and northeast from accumulation zones in the coast mountains ice flow was influenced by to pography major late glacial lakes developed in the nechako river valley and the knewstubb lake region because po tential drainage routes were blocked by ice

displacement along the haiyuan fault associated with the great 1920 haiyuan china earthquake abstract we used a plane table and an alidade to construct detailed topographic maps of offset features stream channels dry gullies and old terrace walls along the fault zone that ruptured during the 1920 haiyuan earthquake m 8 7 in ningxia and gansu china the maximum displacement appears to have reached 10 m at shikaguangou between the salt lake and xianzhou basins in southern ningxia the average displacement along the 100 km of the fault that we studied was about 8 m assuming that the average slip rate to be between 5 and 10 mm yr the recurrence interval for events similar to that in 1920 would be about 800 to 1600 yr

mineralization pathways in lake sediments with different oxygen and organic carbon supply the intensity and pathways of mineralization of sedimentary organic matter were investigated in eutrophic lake zug switzerland in a depth transect 25 180 m from oxic to anoxic bottom water we recorded in situ sediment pore water concentration profiles of o2 n o and nh z with a benthic lander system equipped with both oxygen and ion selective electrodes anaerobic sedimentary mineralization ranged from 13 1 to 34 9 mmol carbon c m22 d21 and increased linearly with water depth as determined from the nh z flux rates in the anoxic pore water and the molar c nitrogen n ratio of the surface sediment a parallel increase of the total organic carbon concentration of the sediment was attributed to lateral transfer of resuspended sedimentary matter denitrification was estimated from nitrate profiles and contributed only 1 5 3 2 to the total organic carbon mineralization at any water depth aerobic respiration and oxidation of reduced compounds were calculated from o2 microprofiles and pore water data of dissolved mn ii fe ii s ii and ch4 when the o2 concentration exceeded 0 15 mmol l 21 in the sediment overlying water 41 58 or 12 4 18 1 mmol c m 22 d 21 was mineralized aerobically whereas at lower concentrations 0 04 mmol l21 92 of organic carbon was mineralized anaerobically total benthic mineralization of organic carbon was 26 9 34 9 mmol c m22 d21 a budget including particulate as well as dissolved reduced compounds in the sediment indicated that 95 of the anaerobic mineralization was due to methanogenesis oxidation of ch4 consumed 39 56 of the o2 at the sediment water interface oxygen exposure times for these sediments were estimated to be on the order of weeks to months these time spans are too short to change the reactivity spectrum of sedimentary organic matter

coseismic and early post seismic slip associated with the 1999 izmit earthquake turkey from sar interferometry and tectonic field observations summary we use combined tectonic field observations and sar data to determine an improved model of the slip associated with the 1999 izmit earthquake which ruptured the north anatolian fault at the eastern end of the sea of marmara the leading goal is to understand the main features of the coseismic and post seismic deformation which are captured together in the sar data to achieve this we make a critical analysis of the ers1 2 sar data which allows atmospheric effects to be identified and removed we also use detailed field mapping and measurements of the earthquake surface rupture dislocations in elastic half space and a forward modelling strategy allow us to obtain a slip model by steps a trial and error approach is combined with conventional inversion techniques to determine the slip in the different regions of the fault the sar data are well explained with three main zones of high slip along the fault releasing a total moment of 2 3 10 20 nm mw 7 6 which is higher than the seismological estimates 1 7 2 0 10 20 n m the inhomogeneous slip distribution correlates with fault segments identified at the surface the izmit rupture appears to have extended 30 km west of the hersek peninsula into the sea of marmara with slip tapering fro m2mt ozero the western end of the rupture is located 40 km sse from istanbul we show that some features seen near to mudurnu and gevye and previously interpreted as slip on secondary faults are explained mostly as atmospheric effects correlated with the topography using our approach and the available gps data we obtain a slip model that represents the coseismic slip alone which suggests that the moment release during the main shock was 1 9 10 20 nm mw 7 5 consistent with the seismological estimates we conclude that the sar data include the effects of 2 m of fast after slip during the month following the main shock within a zone of the fault located 12 24 km below the epicentral region near the hypocentre at a depth of 18 km the fault appears to have experienced dynamic slip of 1 m associated with the main shock followed by 2 m of rapidly decelerating post seismic shear during the following month we suggest that the distribution of heterogeneous slip and loading along the different fault segments may be important factors controlling the propagation of large earthquake ruptures along the north anatolian fault

influence of water column anoxia on the elemental fractionation of carbon and phosphorus during sediment diagenesis abstract organic carbon oxidation and benthic total phosphorus flux measurements from sites covering a range of bottom water oxygen concentrations have been compiled the data show that p regeneration relative to carbon oxidation is much more extensive in sediments overlain by oxygen depleted waters these results are consistent with studies showing that low oxygen bottom water concentrations correlate with reduced total phosphorus burial efficiencies and enhanced organic carbon burial efficiencies based on these observations a positive feedback is proposed between water column anoxia enhanced benthic phosphorus regeneration and marine productivity this feedback may help explain the widespread accumulation of organic rich marine sediments from anoxic waters observed in the geologic record

optical dating studies of postglacial aeolian deposits from the south central interior of british columbia canada abstract tests of the validity of optical dating of the fine grained 4 11 m component of aeolian deposits from six sites in south central british columbia using 1 4 ev infrared excitation of potassium feldspars were made making use of known age tephra beds at one site on the western side of the fraser valley samples bracketing the mazama 7 5 7 6 ka cal yrs and bridge river tephras 2 3 ka cal yrs yielded optical ages in accordance with the known ages when a correction for thermal transfer was used the same method was applied to aeolian deposits on the fraser plateau known to have been deposited between 14 and 2 3 ka cal yrs the ages obtained from five samples from four separate exposures spanning 10 km varied from 30 to 94 ka clearly indicating that this sediment was not exposed to sufficient sunlight prior to burial as a result of a detailed investigation it is suggested that the reason is that some grains had been transported over short distances

spatiotemporal evolution of a transient slip event on the san andreas fault near parkfield california 1 in 1993 several baselines of the two color electronic distance meter edm network at parkfield california deviated from their long term rates coincident with anomalous observations from nearby strain meters and a creep meter as well as an increase in microseismicity between october 1992 and december 1994 three m 4 5 earthquakes occurred beneath middle mountain near the hypocenter of the 1934 and 1966 parkfield m6 events we analyzed the two color edm data using a kalman filtering based technique to image the spatiotemporal evolution of slip on the fault at parkfield between the mid 1980s and 2003 this method accounts for localized random walk motion of the geodetic monuments and a prominent seasonal signal that affects many baselines we find that a slip rate increase occurred between january 1993 and july 1996 on the upper 8 km of the fault near middle mountain the peak estimated slip rate during this time was 49 mm yr which exceeds the long term geologic rate of 35 mm yr the slip rate evolution appears episodic with an initial modest increase after the m4 3 earthquake and a much larger jump following the shallower m4 7 event in december 1994 this temporal correlation between inferred slip and seismicity suggests that the moderate earthquakes triggered the aseismic fault slip the edm data cannot resolve whether transient slip propagated across the nucleation zone of the 1934 and 1966 m6 parkfield earthquakes however transient slip and its associated stress release in the hypocentral area of previous parkfield events is consistent with the nucleation of the 2004 m6 parkfield earthquake elsewhere on the fault

evidence for enhanced phosphorus regeneration from marine sediments overlain by oxygen depleted waters phosphorus regeneration and burial fluxes determined from in situ benthic flux chamber and solid phase measurements at sites on the californian continental margin peruvian continental slope north carolina continental slope and from the santa monica basin california are reported comparison of these sites indicates that o2 depleted bottomwaters enhance p regeneration from sediments diminishing overall phosphorus burial efficiency based on these observations a positive feedback linking ocean anoxia enhanced benthic phosphorus regeneration and marine productivity is proposed on shorter timescales these results also suggest that o2 depletion in coastal regions caused by eutrophication may enhance p regeneration from sediments thereby providing additional p necessary for increased biological productivity