the seismic cycle in the area of the 2011 mw9 0 tohoku oki earthquake we model seismic and aseismic slip on the japan megathrust in the area of the m w9 0 2011 tohoku oki earthquake based on daily time series from 400 gps stations of the geonet network and campaign measurements of six sea floor displacements the coseismic and postseismic slip distributions are inverted simultaneously using principal component analysis based inversion method pcaim exploring a wide range of boundary conditions and regularization constraints we found the coseismic slip distribution to be quite compact with a peak slip between 30 and 50 m near the trench our model shows deep afterslip fringing the downdip edge of the coseismic rupture but also a dominant zone of shallow afterslip afterslip over the first 279 days following the main shock represents about 40 of the coseismic moment we compare the coseismic and postseismic models with an interseismic coupling model derived from inland and sea bottom measurements determined in a self consistent manner assuming that seismic and aseismic slip had to match the long term slip rate along the megathrust the recurrence time of m w9 0 earthquakes is estimated to 100 300 years while historical and paleotsunami records suggest a return period more of the order of 1000 years the discrepancy is smaller if the shallower portion of the megathrust is assumed to produce both aseismic slip as the afterslip model suggests and seismic slip during occasional large tsunamigenic earthquakes

10be inventories in alpine soils and their potential for dating land surfaces abstract to exploit natural sedimentary archives and geomorphic landforms it is necessary to date them first landscape evolution of alpine areas is often strongly related to the activities of glaciers in the pleistocene and holocene at sites where no organic matter for radiocarbon dating exists and where suitable boulders for surface exposure dating using in situ produced cosmogenic nuclides are absent dating of soils could give information about the timing of landscape evolution this paper explores the applicability of soil dating using the inventory of meteoric 10be in alpine soils for this purpose a set of 6 soil profiles in the swiss and italian alps was investigated the surface at these sites had already been dated using the radiocarbon technique or the surface exposure determination using in situ produced 10be consequently a direct comparison of the ages of the soils using meteoric 10be and other dating techniques was made possible the estimation of 10be deposition rates is subject to severe limitations and strongly influences the obtained results we tested three scenarios using a the meteoric 10be deposition rates as a function of the annual precipitation rate b a constant 10be input for the central alps and c as b but assuming a pre exposure of the parent material the obtained ages that are based on the 10be inventory in soils and on scenario a for the 10be input agreed reasonably well with the age using surface exposure or radiocarbon dating the ages obtained from soils using scenario b produced ages that were mostly too old whereas the approach using scenario c seemed to yield better results than scenario b erosion calculations can in theory be performed using the 10be inventory and 10be deposition rates an erosion estimation was possible using scenario a and c but not using b the calculated erosion rates using these scenarios seemed to be plausible with values in the range of 0 57 mm ky the dating of soils using 10be has several potential error sources analytical errors as well as errors from other parameters such as bulk soil density and soil skeleton content have to be taken into account the error range was from 8 up to 21 furthermore uncertainties in estimating 10be deposition rates substantially influence the calculated ages relative age estimates and under optimal conditions absolute dating can be carried out age determination of alpine soils using 10be gives another possibility to date surfaces when other methods fail or are not possible at all it is however not straightforward quite laborious and may consequently have some distinct limitations

five million year10be record in chinese loess and red clay climate and weathering relationships 10be measurements in bulk samples in different size fractions in selective chemically leached fractions of several representative loess paleosol sequences and in the underlying red clay sediments from the chinese loess plateau back to ca 5 ma were made using the ams accelerator mass spectrometer our data support but considerably extend the earlier studies of shen and beer and their colleagues in the upper 0 75 ma luochuan loess paleosol sequences the effect of climatic change is dramatically expressed by10be concentrations 1 in the red clay sediments for which we estimate model accumulation rates of 5 8 and 8 7 m ma 1 for the upper sequences in lingtai and baoji respectively 2 in the paleosols where soil maturation processes are manifest in the10be distribution within different size fractions accompanied by downward movement to zones of high authigenic mineral concentration and 3 in loess samples which at deposition had an appreciable endowment of10be from the dust source regions on the basis of leaching experiments we estimate that on average the paleosol layers lost about 3 3 of their initial10be content to the underlying layers by transport with water finally we estimate that the relative average zonal precipitation rate during glacial periods was 2 3 the average interglacial value the estimates of the initial10be concentrations and dust composition are consistent with the measured values for the recent atmospheric dust falls sampled from the loess plateau and the shandong peninsula

the detection of low magnitude seismic events using array based waveform correlation summary it has long been accepted that occurrences of a known signal are most effectively detected by cross correlating the incoming data stream with a waveform template such matched signal detectors have received very little attention in the field of detection seismology because there are relatively few instances in which the form of an anticipated seismic signal is known a priori repeating events in highly confined geographical regions have been observed to produce very similar waveforms and good signals from events at a given site can be exploited to detect subsequent co located events at lower magnitudes than would be possible using traditional power detectors even greater improvement in signal detectability can be achieved using seismic arrays running correlation coefficients from single sensors can be stacked over an array or network to result in a network correlation coefficient displaying a significant array gain if two events are co located the time separating the corresponding patterns in the wave train as indicated by the cross correlation function is identical for all seismic stations and this property means that the correlation coefficient traces are coherent even when the waveforms are not we illustrate the power of array based waveform correlation using the 1997 august 16 kara sea event the weak event that occurred 4 hr after the main event was barely detected using an sta lta detector on the spits array but is readily detected by signal matching on a single channel the main event was also recorded by the far more distant norsar array but no conventional detection can be made for the second event a clear detection is however made when the correlation coefficient traces are beamformed over all sensors of the array we estimate the reduction in detection threshold of a test signal on a regional seismic array using waveform correlation by scaling down a master signal and immersing it into seismic noise we show that for this case waveform correlation using a single channel detects signals of approximately 0 7 orders of magnitude lower than is possible using an sta lta detector on the array beam waveform matching on the full array provides an additional improvement of approximately 0 4 magnitude units we describe a case study in which small seismic events at the barentsburg coal mine on spitsbergen were detected using the signals from a major rockburst as master waveforms many spurious triggers occurred in this study whereby short sections of signal exhibited coincidental similarity with unrelated incoming wave fronts we demonstrate how such false alarms can almost always be identified and screened out automatically by performing frequency wavenumber analysis upon the set of individual correlation coefficient traces

short and long term delivery rates of meteoric 10be to terrestrial soils well constrained long term average meteoric 10be deposition rates are important when meteoric 10be is used as a chronometer or tracer of earth surface processes to constrain meteoric 10be delivery to terrestrial soils we estimate time integrated 10be deposition rates from meteoric 10be inventories measured in dated soils and compare these results to a new synthesis of short term measurements of 10be in precipitation comparison of these long term rates to short term measurements suggests that short term measurements likely predict long term meteoric 10be deposition rates within uncertainties of 20 in precipitation measurements it is possible to deconvolve the contribution of atmospherically produced primary meteoric 10be from recycled meteoric 10be delivered by terrestrial dust if a second isotope is measured that quantifies either the recycled or primary components of meteoric 10be deposition we use dust concentration dependent differences between 7be and 10be measurements to make new estimates of the recycled contribution to total meteoric 10be flux delivered to the earth s surface these dust corrected data show a strong linear dependence between precipitation amount and primary meteoric 10be flux concentrations of primary meteoric 10be in mid and low latitude precipitation vary predictably by latitude between 0 63 104 and 2 05 104 atoms cm3 of precipitation providing a first order estimate of primary meteoric 10be deposition for a given latitude and precipitation rate

interplate quasi static slip off sanriku ne japan estimated from repeating earthquakes 1 space time distribution of quasi static slip on the plate boundary off sanriku northeastern ne japan was estimated by using small repeating earthquakes we found 2509 repeating earthquakes occurring on the plate boundary for the last 17 years based on the interpretation that these events are caused by repeating slips of small asperities surrounded by stable sliding area we regarded these repeating events as creepmeters embedded on the plate boundary the results show that deeper portions of the plate boundary are sliding almost stably and earthquakes with magnitudes more than 6 are accompanied by quasi static slips in the surrounding areas

late quaternary paleohydrology in the north american great plains inferred from the geochemistry of endogenic carbonate and fossil ostracodes from devils lake north dakota usa abstract devils lake north dakota is a closed basin lake in which water chemistry is responsive to hydrological changes making it a valuable resource for documenting paleoclimate conditions ostracode trace element and bulk carbonate geochemistry in a core are used to generate a 12 000 year record of salinity fluctuations the relative amounts of sr ca and ba in the bulk carbonate fraction can be linked mechanistically to changes in sediment mineralogy calcite aragonite and or solute chemistry whereas the elemental geochemistry of ostracode valves reflect solute chemistry associated minima in sr ca and maxima in mg ca in ostracode valves from the devils lake core may be due to aragonite mediation of sr chemistry during the precipitation of multiple mineral phases during more saline intervals the devils lake record can be divided into four hydrological periods on the basis of the geochemical proxies a 12 5 9 k y low salinity b 9 5 4 5 k y fluctuating saline conditions with a maximum at about 8 k y c 4 5 3 5 k y low salinity phase but probably not as fresh as at 12 5 9 k y d 3 5 k y present saline phase although generally less so than 9 5 4 5 k y however a large degree of variability characterizes the entire record suggesting the absence of long term climatic stability in this region

propagation of slow slip leading up to the 2011 mw 9 0 tohoku oki earthquake many large earthquakes are preceded by one or more foreshocks but it is unclear how these foreshocks relate to the nucleation process of the mainshock on the basis of an earthquake catalog created using a waveform correlation technique we identified two distinct sequences of foreshocks migrating at rates of 2 to 10 kilometers per day along the trench axis toward the epicenter of the 2011 moment magnitude mw 9 0 tohoku oki earthquake in japan the time history of quasi static slip along the plate interface based on small repeating earthquakes that were part of the migrating seismicity suggests that two sequences involved slow slip transients propagating toward the initial rupture point the second sequence which involved large slip rates may have caused substantial stress loading prompting the unstable dynamic rupture of the mainshock

very low frequency earthquakes off the pacific coast of tohoku japan we found very low frequency earthquakes vlfes at a shallow subduction zone close to the japan trench off the pacific coast of tohoku japan centroid moment tensor solutions of vlfes showed reverse fault mechanisms with a compression axis in the east west direction a cross correlation analysis of seismograms with template events between 2005 and 2013 revealed three major vlfe clusters and their temporal evolution a vlfe cluster in the central off tohoku region located in the large slip area of the 2011 tohoku earthquake was detectable only before the tohoku earthquake however vlfes in the northern and southern off tohoku regions at the rim of the large slip area were activated after the tohoku earthquake the change in the activity may reflect the stress redistribution by the coseismic and or afterslip processes of the tohoku earthquake

repeating earthquake activities associated with the philippine sea plate subduction in the kanto district central japan a new plate configuration revealed by interplate aseismic slips abstract we detect repeating earthquakes associated with the philippine sea plate subduction to reveal the plate configuration in the kanto district we find 140 repeating earthquake groups with 428 events by waveform similarity analysis most repeating earthquakes in the eastern part of the kanto district occur with a regular time interval they have thrust type focal mechanisms and are distributed near the upper surface of the philippine sea plate these observations indicate that the repeating earthquakes there occur as a repetition of ruptures on the isolated patches distributed on the plate boundary owing to the concentration of stress caused by aseismic slips in the surrounding areas this shows that the distributions of repeating earthquakes suggest the aseismic slips in the surrounding areas of small patches we determine spatial distributions of repeating earthquakes in the eastern part of the kanto district and find that they correspond to the upper boundary of the philippine sea plate that is the upper boundary of the oceanic crust layer of the philippine sea plate the plate geometry around choshi is newly constrained by repeating earthquake data and a rather flat geometry in the eastern part of the kanto district is revealed the obtained geometry suggests uplift of the philippine sea plate due to the collision with the pacific plate beneath choshi repeating earthquakes in the western part of the kanto district have extremely shorter recurrence times and their focal mechanisms are not of the thrust types these repeating earthquakes are classified as burst type activity and likely to occur on the preexistent fault planes which are distributed around the collision zone between the philippine sea plate and the inland plate the variation among the repeating earthquake activities in the kanto district indicates that regular repetition of repeating earthquakes is possible only on the plate boundary with a smooth and simple geometry

deep fault plane geometry inferred from multiplet relative relocation beneath the south flank of kilauea dense microearthquake swarms occur in the upper south flank of kilauea providing multiplets composed of hundreds of events the similarity of their waveforms and the quality of the data have been sufficient to provide accurate relative relocations of their hypocenters a simple and efficient method has been developed which allowed the relative relocation of more than 250 events with an average precision of about 50 m horizontally and 75 m vertically relocation of these events greatly improves the definition of the seismic image of the fault that generates them indeed relative relocations define a plane dipping about 6 northward although corresponding absolute locations are widely dispersed in the swarm a composite focal mechanism built from events providing a correct spatial sampling of the multiplet also gives a well constrained northward dip of about 5 to the near horizontal plane this technique thus collapses the clouds of hypocenters of single event locations to a plane coinciding with the slip plane revealed by previous focal mechanism studies we cannot conclude that all south flank earthquakes collapse to a single plane there may locally be several planes perhaps with different dips and depths throughout the south flank volume the 6 northward dipping plane we found is too steep to represent the overall flexure of the oceanic crust under the load of the island of hawaii this plane is probably an important feature that characterizes the basal slip layer below the upper south flank of kilauea volcano differences in seismicity rate and surface deformations between the upper and lower south flank could be related to the geometry of this deep fault plane the present work illustrates how high precision relative relocations of similar events in dense swarms combined with the analysis of geodetic measurements can help to describe deep fault plane geometry systematic selection and extensive relative relocation of similar earthquakes could be attempted in other well instrumented highly seismic areas to provide reliable basic information especially useful for understanding of earthquake generation processes

el nino southern oscillation signal associated with middle holocene climate change in intercorrelated terrestrial and marine sediment cores north island new zealand a synchronous textural variation in intercorrelated high resolution sediment records from floodplain continental shelf and continental slope settings of the eastern north island new zealand provides evidence of increased storminess after ca 4 ka an upcore change in sediment texture reflects the transition to landsliding which supplanted fluvial incision as the dominant mode of sediment production in the middle holocene this signal which appears in all three records indicates a regional response to external forcing and records the impact of an intensified atmospheric circulation marking the establishment of the contemporary climate that is strongly influenced by the el nino southern oscillation the change in climate was a hemispheric event and in the southern hemisphere its timing is confirmed by independent proxy records from elsewhere in new zealand and the circum south pacific region

a 200 kyr record of cosmogenic radionuclide production rate and geomagnetic field intensity from 10be in globally stacked deep sea sediments the reconstruction of geomagnetic field intensity variations during the last 200 kyr from paleomagnetic data is at present the subject of numerous studies and major debate there is currently no generally accepted record here we present a global stacked record of 230thex normalized 10be deposition in marine sediments representing relative variations in 10be production rate which are translated into field intensity variations the record shows major periods during which the field intensity was between 10 and 40 of the present day value namely 30 42 60 75 85 110 and 180 192 kyr b p our results are compared to independently derived paleomagnetic studies and th u calibrations of 14c dates on corals during most of the observed period the geomagnetic field intensity was weaker than today resulting in an overall 30 reduced value for the last 200 kyr

application of cosmogenic 10be to dating soils on the raised coral reef terraces of kikai island southwest japan 10be concentrations of six soils on the raised coral reef terraces of kikai island southwest japan range from 0 80 to 7 17 109 atoms g 1 the annual deposition rate of 10be from the atmosphere to kikai island from 2000 to 2002 ranges from 2 0 to 3 5 106 atoms cm 2 year 1 with a mean of 2 8 0 7 106 atoms cm 2 year 1 minimum absolute ages calculated from the inventory of meteoric 10be in the soils and the annual deposition rate of 10be are initial rendzina like soil 8 ka rendzina like soil 18 ka brown rendzina like soil 56 ka terra fusca like soil 127 ka terra rossa like soil 136 ka and intergrade between terra rossa like and red yellow soil 102 ka therefore it was concluded that soil formation during the first 60 000 years would be as rendzina like soils and more than 100 000 years would be required for red yellow soils to develop on raised coral reef terraces under subtropical humid climatic conditions

beryllium 10 transport to antarctica results from seasonally resolved observations and modeling 1 cosmogenic 10be measured in polar ice cores has important application in the reconstruction of past solar activity however the processes controlling its atmospheric transport and deposition to the ice sheets are not fully understood here we use the seasonal changes in 10be concentrations in a 10 year monthly resolved ice core record from the law dome site east antarctica in conjunction with echam5 ham general circulation model gcm simulations of 10be and 7be deposition as tools to examine this problem maximum 10be concentrations are observed in the ice core during the austral late summer to early autumn summer autumn while minimum concentrations are observed during the austral winter the gcm simulations corroborated by earlier observations of 10be 7be ratios in antarctica from the georg von neumayer air sampling station suggest that the 10be concentration maximum is linked to direct input of stratospheric 10be from the antarctic stratosphere to the lower levels of the antarctic troposphere during the austral summer autumn this result contrasts with the modeled transport of 10be to greenland where the seasonal maximum in stratospheric input is seen in the late winter to spring synchronous with the timing of the seasonal maximum in midlatitude stratosphere to troposphere exchange our results suggest that a different combination of processes is responsible for the transport of 10be to the antarctic and greenland ice sheets

calibrating a long term meteoric 10be accumulation rate in soil 1 using 13 samples collected from a 4 1 meter profile in a well dated and stable new zealand fluvial terrace we present the first long term accumulation rate for meteoric 10 be in soil 1 68 to 1 72 10 6 at cm 2 yr integrated over the past 18 ka site specific accumulation data such as these are prerequisite to the application of meteoric 10 be in surface process studies our data begin the process of calibrating long term meteoric 10 be delivery rates across latitude and precipitation gradients our integrated rate is lower than contemporary meteoric 10 be fluxes measured in new zealand rainfall suggesting that long term average precipitation dust flux or both at this site were less than modern values with accurately calibrated long term delivery rates such as this meteoric 10 be will be a powerful tool for studying rates of landscape change in environments where other cosmogenic nuclides such as in situ 10 be cannot be used

meteoric 10be clay and extractable iron depth profiles in the colorado front range implications for understanding soil mixing and erosion abstract analyzing meteoric 10be in soil profiles along with soil measurements such as pedogenic fe and clay content permits better understanding of meteoric 10be transport in soils soil formation and hillslope geomorphology this study presents meteoric 10be depth profiles from saprolite derived soil catenas sampled in the gordon gulch catchment colorado front range and from nearby c 130 and 15 ka glacial moraines we compare meteoric 10be data with more classically used soil analyses of clay and extractable iron fed content meteoric 10be and fed do not show consistent trends in the hillslope profiles meteoric 10be and clay concentrations however generally decrease with depth and highest concentrations of 10be in horizons coincide with highest clay concentrations soils at moraine sites are better developed than those on hillslopes and correlations of 10be fed and clay are stronger in gordon gulch south facing hillslopes display meteoric 10be bulges at depth and lower near surface concentrations compared to the declining profiles and higher near surface concentrations of north facing hillslopes the aspect differences imply that south facing hillslopes experience greater vertical mixing than north facing hillslopes and that greater lateral transport and erosion has occurred over the last 15 20 ka on south facing hillslopes relative to north facing hillslopes meteoric 10be depth profiles at moraine sites display bulge profiles with highest meteoric 10be concentrations in b horizons reflecting landform stability and pedogenic processes overall our data demonstrate that signatures of chemical weathering in soils fed and clay may or may not correlate to the meteoric 10be added through atmospheric deposition and that profile shape of meteoric 10be can provide insight into the relative contribution of vertical mixing and surface erosion in relation to catena location and aspect during hillslope evolution

preliminary estimates of regolith generation and mobility in the susquehanna shale hills critical zone observatory pennsylvania using meteoric 10be abstract this study seeks to quantify the rate and timing of regolith generation in the critical zone at the susquehanna shale hills critical zone observatory ssho meteoric 10 be depth profiles were determined using measurements from 30 hillslope soil and bedrock core samples in an effort to constrain 10 be inventories the ssho is located in the temperate climate zone of central pennsylvania and comprises a first order watershed developed entirely on a fe rich organic poor silurian aged shale two major perturbations to the landscape have occurred at ssho in the geologically recent past including significant and sustained periglacial activity until after the retreat of the laurentide ice sheet 21 ka and deforestation during early colonial land use bulk soil samples n 16 were collected at three locations along a planar hillslope on the southern ridge of the catchment representing the ridge top mid slope and valley floor rock chip samples n 14 were also collected from a 24 m deep core drilled into the northern ridge top all meteoric 10 be concentration profiles show a declining trend with depth with most of the 10 be retained in the uppermost decimeters of the soil meteoric 10 be inventories are higher at the mid slope and valley floor sample sites at 3 71 0 02 10 10 at cm 2 and 3 69 0 02 10 10 at cm 2 than at the ridge top site 1 90 0 01 10 10 at cm 2 the 10 be inventory at the convex ridge top site implies a minimum residence time of 10 6 ka or if erosion is steady an erosion rate of 19 4 0 2 m my

10be distribution in soils from merced river terraces california abstract the distribution and residence time of cosmogenic 10 be in clay rich soil horizons is fundamental to understanding and modelling the migration of 10 be on terrestrial sediments and in groundwater solutions we have analyzed seven profiles of clay rich soils developed from terrace sediments of the merced river california the terraces and soils of increasing age are used to compare the 10 be inventory with a simple model of accumulation decay and erosion the data show that the distribution of 10 be varies with soil horizon clay content that the residence time of 10 be in these horizons exceeds 10 5 years and that to a rough approximation the inventory of 10 be in a thoroughly sampled soil profile fits the equation n q em 1 e where q is delivery rate e is erosion rate m is the concentration of 10 be in the eroding surface layer is the decay constant and t is the age of the depositional unit from which the soil has developed the general applicability of this model is uncertain and warrants further testing in well calibrated terrace sequences

migrating pattern of deformation prior to the tohoku oki earthquake revealed by grace data understanding how and when far field continuous motions lead to giant subduction earthquakes remains a challenge an important limitation comes from an incomplete description of aseismic mass fluxes at depth along plate boundaries here we analyse earth s gravity field variations derived from grace satellite data in a wide space time domain surrounding the mw 9 0 2011 tohoku oki earthquake we show that this earthquake is the extreme expression of initially silent deformation migrating from depth to the surface across the entire subduction system our analysis indeed reveals large scale gravity and mass changes throughout three tectonic plates and connected slabs starting a few months before march 2011 before the tohoku oki earthquake rupture the gravity variations can be explained by aseismic extension of the pacific plate slab at mid upper mantle depth concomitant with increasing seismicity in the shallower slab for more than two years after the rupture the deformation propagated far into the pacific and philippine sea plate interiors suggesting that subduction accelerated along 2 000 km of the plate boundaries in march 2011 this gravitational image of the earthquake s long term dynamics provides unique information on deep and crustal processes over intermediate timescales which could be used in seismic hazard assessment deformation migrated from depth towards the surface in the months leading up to the 2011 tohoku oki earthquake according to analyses of satellite gravity data

the global average production rate of10be precipitation collected in continuously open containers for about a year at seven sites around the united states was analyzed for10be 90sr 210pb and238u based on these data and long term precipitation 90sr and210pb delivery patterns the stratospheric tropospheric and recycled10be components in the collections were estimated and the global10be production rate was assessed single station production rate estimates range from 0 52 106 atoms cm 2 yr 1 to 2 64 106 atoms cm 2 yr 1 the mean value is 1 21 106 atoms cm 2 yr 1 with a standard error of 0 26 106 atoms cm 2 yr 1

tracing hillslope sediment production and transport with in situ and meteoric 10be 1 we use in situ produced and meteoric 10be analyzed in soils from 28 pits on four hillcrest parallel transects along a 14 hillslope in the great smoky mountains north carolina as tracers of soil production and transport we rely upon amalgamation both to investigate and smooth spatial variability in 10be concentrations lidar indicates that the hillslope is topographically complex and that soil is moved downslope diffusively until it encounters the ephemeral channel network and is rapidly exported in situ produced 10be measured in depth profiles indicates that over millennial timescales soils are mixed above the soil saprolite boundary in contrast meteoric 10be concentrations increase with depth and are correlated to concurrent increases of dithionite extractable al and ph observations explained by similar al and be mobility in the soil the concentrations of both meteoric and in situ produced 10be increase downslope proportional to the maximum soil particle path length the data suggest virtual downslope soil velocities of 1 1 1 7 cm yr 1 in a well mixed active transport layer 60 cm thick the thickness of this transport layer is constant downslope and depends on the rooting depth and consequent root wad thickness of downed trees on the slope both of which reflect depth to the soil saprolite boundary both meteoric and in situ produced 10be suggest that soil production is balanced by surface denudation at rates between 10 and 13 m myr 1 soil residence times on the slope range from 21 to 33 kyr based on the meteoric 10be inventories major element geochemical analysis suggests little if any elemental loss during soil transport downslope

a decadal scale deformation transient prior to the 2011 mw 9 0 tohoku oki earthquake gps time series in northeast japan exhibit nonlinear trends from 1996 to 2011 before the mw 9 0 2011 tohoku oki earthquake after removing reference frame noise we model time series as linear trends plus constant acceleration correcting for coseismic and postseismic effects from the numerous mw 6 5 earthquakes during this period we find spatially coherent and statistically significant accelerations throughout northern honshu large areas of japan outside the tohoku region show insignificant accelerations demonstrating that the observation is not due to network wide artifacts while the accelerations in northern tohoku sanriku area can be explained by decaying postseismic deformation from pre 1996 earthquakes the accelerations in south central tohoku appear unrelated to postseismic effects the latter accelerations are associated with a decrease in average trench normal strain rate and can be explained by increasing slip rate on the japan trench plate interface and or updip migration of deep aseismic slip in the decades before the 2011 tohoku oki earthquake

upper tropospheric inversion and easterly jet in the tropics 1 shipboard radiosonde measurements revealed a persistent temperature inversion layer with a thickness of 200 m at 12 13 km in a nonconvective region over the tropical eastern pacific along 2 n in september 1999 simultaneous relative humidity measurements indicated that the thin inversion layer was located at the top of a very wet layer with a thickness of 3 4 km which was found to originate from the intertropical convergence zone itcz to the north radiative transfer calculations suggested that this upper tropospheric inversion uti was produced and maintained by strong longwave cooling in this wet layer a strong easterly jet stream was also observed at 12 13 km centered around 4 5 n this easterly jet was in the thermal wind balance with meridional temperature gradients produced by the cloud and radiative processes in the itcz and the wet outflow furthermore the jet in turn acted to spread inversions further downstream through the transport of radiatively active water vapor this feedback mechanism may explain the omnipresence of temperature inversions and layering structures in trace gases in the tropical troposphere examination of high resolution radiosonde data at other sites in the tropical pacific indicates that similar utis often appear around 12 15 km the uti around 12 15 km may thus be characterized as one of the climatological inversions in the tropical troposphere forming the lower boundary of the so called tropical tropopause layer where the tropospheric air is processed photochemically and microphysically before entering the stratosphere

a 600 year annual 10be record from the ngrip ice core greenland understanding the link between the sun and climate is vital in the current incidence of global climate change and 10be in natural archives constitutes an excellent tracer for this purpose as cosmic rays enter the atmosphere cosmogenic isotopes like 10be and 14c are formed variations in solar activity modulate the amount of incoming cosmic rays and thereby cosmogenic isotope production atmospherically produced 10be enters natural archives such as sediments and glaciers by wet and dry deposition within about a year of production 10be from natural archives therefore provides information on past solar activity and because these archives also contain climate information solar activity and climate can be linked one remaining question is to what degree 10be in natural archives reflects production and to what extent the local and regional environment overprints the production signal to explore this 10be was measured at annual resolution over the last 600 years in a greenland ice core measurement potentials for these samples benefited from the development of a new laboratory method of co precipitating 10be with niobium to diversify geographic location and archive media type a pioneer study of measuring 10be with annual resolution in varved lake sediments from finland was conducted with samples from the entire 20th century pathways of 10be into lake sediments are more complex than into glacial ice inferring that contemporary atmospheric conditions may not be recorded here it is shown for the first time that tracing the 11 year solar cycle through lake sediment 10be variations is possible results also show that on an annual basis 10be deposition in ice and sediment archives is affected by local environmental conditions on a slightly longer timescale however diverse 10be records exhibit similar trends and a negative correlation with solar activity cyclic variability of 10be deposition persisted throughout past grand solar minima when little or no sunspot activity was recorded 10be levels indicate that although solar activity has been high during the 20th century levels are not unprecedented in the investigated 600 years aerosol 10be 7be values indicate possible influence of stratosphere troposphere exchange on isotope abundance and the production signal

ice sheet erosion and the stripping of tertiary regolith from baffin island eastern canadian arctic abstract the erosion of glaciated regions and concomitant changes in ice sheet dynamics through the pleistocene are poorly documented the baffin island landscape which has been shaped by the foxe sector of the laurentide ice sheet lis contains a variety of glacial and proximal glaciomarine sedimentary archives spanning the pleistocene we examine these records to better understand when tertiary regolith was stripped from beneath the foxe sector of the lis till on the interior plateaux of the island in areas with scoured bedrock have low chemical index of alteration cia values low meteoric 10 be 10 be met concentrations and clay mineralogy consistent with erosion from an unweathered bedrock source however in some areas in between fiord onset zones more weathered till is present containing considerably higher cia values high 10 be met concentrations and secondary clay mineral weathering products implying that the till has persisted on the landscape and weathered during successive glaciations using these weathering signatures we analyze the coastal glaciogenic deposits of the clyde foreland formation cff at two sites for evidence of tertiary regolith removal from the interior of baffin island by lis erosion provenance indicators within the cff demonstrate that pleistocene lis ice flow lines across baffin island have remained generally constant the oldest cff glaciogenic unit likely representing one of the first if not the first lis advances across baffin island had high 10 be met concentrations at the time of deposition consistent with extensive regolith erosion evidence of notably weathered sediment is absent in all younger units suggesting that tertiary regolith was likely largely stripped from the interior of the island by 1 6 0 2 ma

meteoric 10be in soil profiles a global meta analysis abstract in order to assess current understanding of meteoric 10 be dynamics and distribution in terrestrial soils we assembled a database of all published meteoric 10 be soil depth profiles including 104 profiles from 27 studies in globally diverse locations collectively containing 679 individual measurements this allows for the systematic comparison of meteoric 10 be concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings percent clay 9 be and dithionite citrate extracted al positively correlate to meteoric 10 be in more than half of the soils where they were measured but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric 10 be distribution with depth dithionite citrate extracted fe and cation exchange capacity are only weakly correlated to meteoric 10 be percent organic carbon and ph are not significantly related to meteoric 10 be concentration when all data are complied the compilation shows that meteoric 10 be concentration is seldom uniform with depth in a soil profile in young or rapidly eroding soils maximum meteoric 10 be concentrations are typically found in the uppermost 20 cm in older more slowly eroding soils the highest meteoric 10 be concentrations are found at depth usually between 50 and 200 cm we find that the highest measured meteoric 10 be concentration in a soil profile is an important metric as both the value and the depth of the maximum meteoric 10 be concentration correlate with the total measured meteoric 10 be inventory of the soil profile in order to refine the use of meteoric 10 be as an estimator of soil erosion rate we compare near surface meteoric 10 be concentrations to total meteoric 10 be soil inventories these trends are used to calibrate models of meteoric 10 be loss by soil erosion erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected

holocene climate in the northern great plains inferred from sediment stratigraphy stable isotopes carbonate geochemistry diatoms and pollen at moon lake north dakota abstract seismic stratigraphy sedimentary facies pollen stratigraphy diatom inferred salinity stable isotope 18 o and 13 c and chemical composition sr ca and mg ca of authigenic carbonates from moon lake cores provide a congruent holocene record of effective moisture for the eastern northern great plains between 11 700 and 9500 14 c yr b p the climate was cool and moist a gradual decrease in effective moisture occurred between 9500 and 7100 14 c yr b p a change at about 7100 14 c yr b p inaugurated the most arid period during the holocene between 7100 and 4000 14 c yr b p three arid phases occurred at 6600 6200 14 c yr b p 5400 5200 14 c yr b p and 4800 4600 14 c yr b p effective moisture generally increased after 4000 14 c yr b p but periods of low effective moisture occurred between 2900 2800 14 c yr b p and 1200 800 14 c yr b p the data also suggest high climatic variability during the last few centuries despite the overall congruence the biological diatom sedimentological isotopic and chemical proxies were occassionally out of phase at these times the evaporative process was not the only control of lake water chemical and isotopic composition

accuracy of cosmogenic ages for moraines analyses of all published cosmogenic exposure ages for moraine boulders show an average age range of 38 between the oldest and youngest boulders from each moraine this range conflicts with the common assumption that ages of surface boulders are the same as the age of the landform the wide spread in boulder ages is caused by erosion of the moraine surface and consequent exhumation of fresh boulders a diffusion model of surface degradation explains the age range and shows that a randomly sampled small set of boulders n 3 7 will always yield a lower age limit for the moraine the model indicates that for identical dating accuracy six to seven boulders are needed from old and tall moraines 40 000 100 000 yr 50 100 m initial height but only one to four boulders from small moraines 20 000 100 000 yr 10 20 m by following these guidelines the oldest obtained boulder age will be 90 of the moraine age 95 probability this result is only weakly sensitive to a broad range of soil erosion rates our analysis of published boulder ages indicates that 3 of all moraine boulders have prior exposure and 85 of these boulders predate the dated moraine

coupling meteoric 10be with pedogenic losses of 9be to improve soil residence time estimates on an ancient north american interfluve we couple meteoric 10 be measurements with mass balance analysis of 9 be to estimate the soil residence time srt of a biogeomorphically stable ultisol in the southern piedmont physiographic region of the southeastern united states we estimate srt after correcting the meteoric 10 be inventory to account for observed 9 be losses which indicate that more than half of the 9 be weathered from primary minerals has been leached from the upper 18 3 m of the ultisol our estimates of minimum srt range between 1 3 1 4 ma and between 2 6 3 1 ma under high and low 2 0 and 1 3 10 6 atoms cm 2 yr 1 respectively estimates of 10 be delivery denudation rates of the physiographic region corroborate our estimates we redefine pedogenic time constraints in the southern piedmont and demonstrate that the assumption of complete meteoric 10 be retention in acidic soil systems cannot always be made the latter has far reaching consequences for soil sediment river and ocean research using meteoric 10 be

potential slab deformation and plunge prior to the tohoku iquique and maule earthquakes megathrust earthquakes rupture the shallow plate boundary in subduction zones analysis of seismic activity preceding megathrust quakes in japan and chile reveals deep seismicity that may mark plunging of the slabs prior to main fault rupture

relating the spatial variability of chemical weathering and erosion to geological and topographical zones abstract the relationship between the spatial variability of soil elements weathering and erosion rates can be very complex topography abruptly changing elevation gradients and slopes of varying geological composition exert an important influence on weathering trajectories and erosion this complex interconnectivity is only rarely addressed in weathering studies the main objectives of this investigation are therefore to relate weathering and erosion to various and geomorphic units in a dry alpine and threshold landscape having steep slopes kan catchment tehran province iran a number of common weathering indices were tested using a genetic algorithm the best indices are the k na ti ratio the wip weathering index according to parker and the pi product index according to ruxton however the recently suggested 4si m r2 and m f wmin systems discriminate weathering trends more accurately our results show that these soils have a low to moderate weathering stage weathering trajectories point to the active formation of kaolinite and oxyhydroxides river sediments are slightly more weathered and contain the most weathered topsoils and suggest erosion in the catchment is predominantly due to topsoil removal chemical weathering is influenced by the dominant geomorphic units unconsolidated deposits of the quaternary and solid bedrock and landform features combination of altitude and slope aspect does not appear to have a significant impact on weathering denudation erosion rates were determined using meteoric 10be since the fluvial sediments did not contain enough quartz for in situ 10be analyses this procedure has higher uncertainties due to difficulties in estimating the depositional flux of meteoric 10be due to tectonic uplift the erosion rates are very high to maintain a soil layer soil production rates must be also high although annual precipitation is relatively low slope and soil dynamics seem particularly high which leads to a fast turnover of the soil material and maintains the weathering intensity at a rather low to intermediate level

seismic activity preceding the 2011 m w 9 0 tohoku earthquake japan analyzed with multidimensional template matching the observation of a transient slip 1 month before the rupture of the 2011 tohoku earthquake is a conandrum since the area was supposedly fully coupled a better understanding of the mechanisms at work during the preseismic phase is thus fundamental however the configuration of the pacific plate and the location of the tohoku rupture zone 200 km from the coast make it difficult to detect microseismic events in this study we use a multidimensional template matching mdtm technique to detect earthquakes that are hidden in the noise the temporal distribution of these 395 newly detected earthquakes provides new insights on the slip history of the megathrust earthquake epicentral zone the detected events can be separated into two groups 187 low frequency detections below 5 hz that well recorded the episodes of earthquake migration prior to the tohoku earthquake and 208 high frequency detections above 10 hz that occurred close to the rupture zones of the m 4 8 6 earthquakes that struck between the 9 march 2011 m7 3 foreshock and the 30 november 2010 tohoku oki earthquake the seismic rate of these high frequency detection events starts to increase on 30 november 2010 until the tohoku earthquake

beryllium isotope geochemistry in tropical river basins abstract the distributions of beryllium 9 and beryllium 10 in rivers within the orinoco and amazon basins have been examined to extend our understanding of their geochemical cycles and to develop their use both in geochronometry and in studying erosional processes beryllium 9 the stable isotope is weathered from mineral lattices before entering the riverine dissolved or exchangeable phase the cosmogenic radioisotope 10be t 1 2 1 5 myr is produced primarily in the atmosphere and is brought into riverine systems via rainfall in dissolved or exchangeable form it may be used to examine the processes which affect beryllium partitioning between the dissolved and particulate phases ancillary data such as major ion distributions provide a basis for selecting regions in which riverine chemistry is dominated by a single geochemical process allowing examination of its effects on be distributions in isolation analyses of 9be in dissolved and suspended material from rivers with a wide range of chemical compositions indicate that its geochemistry is primarily controlled by two major factors 1 1 its abundance in the rocks of the watershed and 2 2 the extent of its adsorption onto particle surfaces the relative importance of these parameters in individual rivers is determined by the extent of interaction with flood plain sediments and the riverine ph this understanding of 9be geochemistry forms a basis for examination of the geochemical cycling of 10be in rivers which are dominated by interaction with sediments the riverine concentration of dissolved 10be is far lower than that in the incoming rainwater indicating that a substantial proportion of it is retained within the soils of the basin or is adsorbed onto riverine particles however in acidic rivers in which the stable dissolved be concentration is determined by the be level in the rocks of the drainage basin dissolved 10be has essentially the same concentration as in precipitation these observations imply that the soil column in such regions must be saturated with respect to 10be and that the ratio of the inventory to the flux does not represent an age as may be the case in temperate latitudes but rather a residence time

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

spatial and temporal variations in meteoric 10be inventories and long term deposition rates colorado front range abstract atmospherically derived cosmogenic nuclides such as meteoric 10 be offer great potential in quaternary science because they can be used as landform geochronometers and as sediment tracers use of meteoric 10 be inventories for determining landform age soil residence time or erosion rates requires knowing the long term rate of deposition for this cosmogenic nuclide to the earth s surface here we present meteoric 10 be inventories measured at 6 dated sites near the boulder creek critical zone observatory front range colorado each site lies on a relatively stable landform broad moraine or fluvial terrace at slopes between 10 be deposition precipitation dryfall and dust deposition calculated from measured inventories at these sites range from 0 4 to 5 0 10 6 atoms cm 2 yr 1 none of the inventories match expected primary meteoric 10 be deposition rates that global latitude based models or precipitation specific models predict for this region meteoric 10 be inventories and calculated deposition rates at the three older 90 ka sites fall below 0 3 0 7 model predictions inventories and rates at the three pinedale age sites lgm 21 15 ka are higher 1 5 4 than model predictions previous analysis of soils in the front range over the same timeframe as these sites indicate that long term dust accumulation rates are low and associated secondary meteoric 10 be deposition is unlikely to account for the deviation from model predictions at the pinedale age sites in particular long term dustfall would have to be 1 2 orders of magnitude higher to add the meteoric 10 be required to account for measured inventories low inventories at older sites are consistent with loss of meteoric 10 be through physical erosion or selective removal of near surface soil enriched in meteoric 10 be time averaged rates of total meteoric 10 be deposition for these sites are minima we speculate that higher inventories at pinedale age sites reflect the addition of meteoric 10 be due to snowdrifts and or interflow associated with landform location increasing the effective precipitation related primary meteoric 10 be deposition at the sampled sites given these constraints and the spatial variation observed around the front range we suggest that 1 5 0 2 10 6 atoms cm 2 yr 1 is an appropriate long term meteoric 10 be deposition rate to use across much of the front range region that receives 45 55 cm of precipitation a year this long term total meteoric 10 be deposition rate is 30 50 higher than that predicted by global or annual precipitation specific models emphasizing that local calibration of deposition rates is essential for geomorphic studies around the globe

volcanic like low frequency earthquakes beneath osaka bay in the absence of a volcano 1 among the many deep low frequency earthquakes lfes recently discovered worldwide lfes beneath osaka bay western japan are especially unusual their waveforms are monochromatic resembling those of some volcanic lfes but there are no active volcanoes around the area is close to but clearly distinct from a belt of tectonic lfes and is near the site of a large inland earthquake the 1995 kobe earthquake to characterize the activity of these lfes we present an extensive catalog constructed using a matched filter analysis on continuous seismic records with template lfes determined by the japan meteorological agency the relocated catalog of 1378 events over a period of 5 years shows spatially concentrated activity in two volumetric zones with several active periods including successive tremor like events the magnitude frequency statistics satisfy the gutenberg richter law with a b value of 2 unlike tectonic lfes which are highly sensitive to tidal stress the lfes beneath osaka bay show no spectral peak in activity at tidal periods and the overall pattern of the spectrum is similar to that of volcanic lfes beneath sakurajima japan these findings suggest that the osaka bay lfes are almost same as volcanic lfes in origin or at least related to fluid upwelling from the mantle

continuous borehole strain and pore pressure in the near field of the 28 september 2004 m 6 0 parkfield california earthquake implications for nucleation fault response earthquake prediction and tremor near field observations of high precision borehole strain and pore pres sure show no indication of coherent accelerating strain or pore pressure during the weeks to seconds before the 28 september 2004 m 6 0 parkfield earthquake minor changes in strain rate did occur at a few sites during the last 24 hr before the earth quake but these changes are neither significant nor have the form expected for strain during slip coalescence initiating fault failure seconds before the event strain is stable at the 10 11 level final prerupture nucleation slip in the hypocentral region is constrained to have a moment less than 2 10 12 nm m 2 2 and a source size less than 30 m ground displacement data indicate similar constraints localized rupture nucleation and runaway precludes useful prediction of damaging earthquakes coseismic dynamic strains of about 10 microstrain peak to peak were superimposed on volumetric strain offsets of about 0 5 microstrain to the northwest of the epicenter and about 0 2 microstrain to the southeast of the epicenter consistent with right lateral slip observed strain and global positioning system gps offsets can be simply fit with 20 cm of slip between 4 and 10 km on a 20 km segment of the fault north of gold hill m 0 7 10 17 n m variable slip inversion models using gps data and seismic data indicate similar moments observed postseismic strain is 60 to 300 of the coseismic strain indicating incomplete release of accumulated strain no measurable change in fault zone compliance preceding or following the earthquake is indicated by stable earth tidal response no indications of strain change accompany nonvolcanic tremor events reported prior to and following the earthquake

characteristic small earthquake sequence off sanriku northeastern honshu japan 1 we found eight similar earthquakes of m4 8 regularly occurring from 1957 to 1995 on the plate boundary off sanriku northeastern japan the mean recurrence interval of the events is 5 35 years and its standard deviation is only 0 53 years these events have the same focal mechanisms of low angle thrust fault type and their source sizes are estimated to be around 1 km the slip of each event is comparable to the cumulative amount of relative plate motion in the inter seismic period thus these events are probably caused by repeating slip at a small but strong asperity surrounded by creeping zone on the plate boundary the next event was expected to occur by the end of november 2001 with 99 probability and actually m4 7 event occurred on november 13 2001

extended nucleation of the 1999 mw 7 6 izmit earthquake laboratory and theoretical studies suggest that earthquakes are preceded by a phase of developing slip instability in which the fault slips slowly before accelerating to dynamic rupture we report here that one of the best recorded large earthquakes to date the 1999 moment magnitude mw 7 6 izmit turkey earthquake was preceded by a seismic signal of long duration that originated from the hypocenter the signal consisted of a succession of repetitive seismic bursts accelerating with time and increased low frequency seismic noise these observations show that the earthquake was preceded for 44 minutes by a phase of slow slip occurring at the base of the brittle crust this slip accelerated slowly initially and then rapidly accelerated in the 2 minutes preceding the earthquake

pre and postseismic slow slip surrounding the 2011 tohoku oki earthquake rupture abstract slow aseismic slip that accommodates part of the long term plate motion on subduction megathrusts is thought to be strongly related to the occurrence of large earthquakes on the same fault zone however the temporal evolution and spatial distribution of the aseismic slip before major earthquakes and of accelerated postseismic afterslip are largely unconstrained we estimate cumulative offsets of small repeating earthquakes that are interpreted to reflect the in situ aseismic slip history on the subduction zone offshore northeastern japan these data reveal contrasting aseismic slip patterns between the coseismic rupture area of the mw 9 0 tohoku oki earthquake and surrounding portions of the subduction thrust the rupture area is characterised by low and variable slip rates before 2008 and the slip stopped almost completely after the earthquake the region surrounding the rupture area exhibited higher aseismic fault slip rates before the earthquake and clear postseismic slip of up to 1 6 m within 9 months following the main shock the frictional fault properties and complete relief of ambient stress in the central rupture zone of the main shock probably control the observed distribution the postseismic slip shows a more abrupt increase in the region closer to the source suggesting outwards propagation of afterslip small but distinct increases in the slip rate in the 3 yr before the earthquake near the area of large coseismic slip suggests preseismic unfastening of the locked area in the last stage of the earthquake cycle

10be accumulation in a soil chronosequence we have measured the concentration of the cosmogenic isotope10be in soil samples from various horizons at six sites including three independently dated rappahannock river terraces and a previously undated piedmont soil to which we have assigned an age all of the incident10be can be accounted for in one of these soils and a second is within a factor of two in three soils whose concentrations vary widely with depth a significant fraction of the incident10be cannot be accounted for incomplete sampling and enhanced be mobility caused by organic components are the probable reasons for the low inventory of be from these three soils overall the data from these six sites indicate that10be accumulation could be used to assign ages to soils if be is not mobilized and lost from the soil profile

seismological studies at parkfield vi moment release rates and estimates of source parameters for small repeating earthquakes abstract waveform data from a borehole network of broadband seismographic stations have been used to study microearthquakes along the parkfield segment of the san andreas fault saf analysis of almost 10 years of such data demonstrates that much of the seismicity in this region consists of repeating sequences quasiperiodic sequences of earthquakes that are essentially identical in terms of waveform size and location scalar seismic moments have been estimated for 53 of these repeating sequences and combined with equivalent estimates from 8 similar but larger event sequences from the stone canyon section of the fault and the main parkfield sequence these estimates show that seismic moment is being released as a function of time in a very regular manner measurements of the moment release rate combined with an assumed tectonic loading rate lead to estimates of the seismic parameters source area slip and recurrence interval such parameters exhibit a systematic dependence upon source size over a range of 10 10 in seismic moment that can be described by three simple scaling relationships several implications of these scaling relationships are explored including the repeat time of earthquakes average stress drop strength of the fault and heat generated by earthquakes what emerges from this analysis of moment release rates is a quantitative description of an earthquake process that is controlled by small strong asperities that occupy less than 1 of the fault area this means that the fault is highly heterogeneous with respect to stress strength and heat generation such heterogeneity helps to explain many of the apparent contradictions that are encountered in the study of earthquakes such as why faults appear weak why significant heat flow is not observed how significant high frequencies can be generated by large earthquakes and how various geologic features such as pseudotachylytes might form

the depositional flux of meteoric cosmogenic 10be from modeling and observation abstract meteoric cosmogenic 10be is a powerful tracer to quantify dates and rates of earth surface processes over timescales of 103 105 yrs a prerequisite for its applications is knowledge of the flux at which 10be produced in the atmosphere is delivered to the earth surface four entirely independent approaches are available to quantify this flux 1 general circulation models gcm combined with 10be production functions and aerosol dynamics 2 10be in precipitation collections 3 10be inventories in dated soil profiles 4 riverine 10be exported in solid and dissolved forms we compiled and reprocessed published globally distributed 10be flux data from each of these methods and compared them with each other after normalization to a common atmospheric production rate based on precipitation records we propose a simple framework to discriminate between two delivery effects on 10be fluxes in the additive effect water vapor and 10be are continuously accumulating during long distance transport leading to an increase in 10be flux with precipitation rate in the dilution effect the 10be flux is delivered from proximal vapor sources limited by the rate of 10be introduction from the stratosphere and independent of precipitation rate both effects are mostly present in combination and the relative weight of either effect depends on vapor condensation rate and on the ratio of vapor condensation area to precipitation area a comparison between precipitation derived fluxes and gcm derived fluxes shows that half of the precipitation estimates are 2 times greater than gcm derived fluxes by comparison soil and gcm derived fluxes agree within a factor of 2 for more than half 57 of the dataset and the remaining soil estimates 43 are much lower than gcm derived fluxes 71 of 10be flux estimates from riverine export using 10be meteoric 9be ratios also agree with gcm derived fluxes within a factor of 2 we explain the precipitation derived fluxes that commonly exceed all other estimates by short term stochasticity in precipitation events that might introduce a measurement time interval bias towards higher fluxes this bias is not present over longer term 103 105 yrs flux estimates like those from soil profiles soil derived fluxes might still present an underestimation when retention of 10be in soil is incomplete we recommend producing more 10be depositional flux data from soil inventories with full be retention as these generate in our view the most relevant estimates for applications of meteoric 10be on millennial scale earth surface processes

seimological studies at parkfield v characteristic microearthquake sequences as fault zone drilling targets studies at very high resolution of microearthquakes at parkfield california since 1987 reveal a systematic organization in space and time dominated by clustering of nearly identical regularly occurring microearthquakes characteristic events on 10 to 20 m wide patches within the fault zone more than half of the 4000 events in our 1987 to 1996 catalog exhibit this trait in general recurrence intervals 0 5 to 2 yr scale with the magnitude of the repeating events for the on scale range mw 0 2 to 1 3 in this study the similar waveforms superimposed locations quasi periodic recurrence and uniform size of these characteristic events permit relative hypocenter location accuracy of meters and predictable occurrence times within windows of a few months clustered characteristic events occur at depths as shallow as about 3 km and these are feasible targets for deep scientific drilling and observation at the focus of a subsequent small earthquake within an active plate boundary fault zone at parkfield the achievable location accuracy to which a hypocenter can be specified as well as the predictability of its occurrence time appear to be uniquely favorable for in situ fault zone measurements

episodic slow slip events in the japan subduction zone before the 2011 tohoku oki earthquake abstract we describe two transient slow slip events that occurred before the 2011 tohoku oki earthquake the first transient crustal deformation which occurred over a period of a week in november 2008 was recorded simultaneously using ocean bottom pressure gauges and an on shore volumetric strainmeter this deformation has been interpreted as being an m6 8 episodic slow slip event the second had a duration exceeding 1 month and was observed in february 2011 just before the 2011 tohoku oki earthquake the moment magnitude of this event reached 7 0 the two events preceded interplate earthquakes of magnitudes m6 1 december 2008 and m7 3 march 9 2011 respectively the latter is the largest foreshock of the 2011 tohoku oki earthquake our findings indicate that these slow slip events induced increases in shear stress which in turn triggered the interplate earthquakes the slow slip event source area on the fault is also located within the downdip portion of the huge coseismic slip area of the 2011 earthquake this demonstrates episodic slow slip and seismic behavior occurring on the same portions of the megathrust fault suggesting that the faults undergo slip in slow slip events can also rupture seismically

10be in lake lisan sediments a proxy for production or climate abstract the geochemical behavior of 10 be in the modern dead sea hydrological limnological system was studied in order to evaluate the feasibility of using dead sea and lake lisan the late pleistocene precursor of the dead sea sediments as archives of the variations in the 10 be production rate 10 be concentrations in detrital and aragonite material from lake lisan laminated sediments were compared to those measured in modern dust terra rossa soil aeolian in origin loess from the negev desert flood suspended load and waters along a rain flood development pathway the transition from rain to incipient runoff and fully developed floods 10 be concentrations decreased throughout the flood development profile from 8 2 10 3 atoms g 1 in the runoff down to 1 10 3 atoms g 1 in dead sea brine due to fast removal of 10 be by the soil and dust particles thus most of the 10 be in the lake is contained within the detrital sediments that collect the 10 be transported by particles from the surrounding terrain e g desert dust with 1 6 0 8 10 8 atoms g 1 and terra rossa soil material with up to 12 5 0 5 10 8 atoms g 1 the high stand periods of lake lisan were characterized by annual deposition of silty detritus sediments reflecting rapid transfer of desert dust to the lake by floods indeed the bulk sediments of lake lisan in which 10 be is associated mainly with silty detritus display 10 be concentrations similar to those of desert dust this demonstrates that 10 be variations were modulated by climate i e particle transport significant positive 10 be peaks up to 1 6 10 8 atoms g 1 appear during intervals of geomagnetic anomalies in lake lisan stratigraphy and in the global record i e during the laschamp geomagnetic event at 41 ka bp this indicates that 10 be atmospheric production signal is superimposed on the climatic 10 be variations we conclude that after de trending of the climatic signal lake lisan sediments may be used as an archive for atmospheric 10 be production

months long thousand kilometre scale wobbling before great subduction earthquakes megathrust earthquakes are responsible for some of the most devastating natural disasters1 to better understand the physical mechanisms of earthquake generation subduction zones worldwide are continuously monitored with geophysical instrumentation one key strategy is to install stations that record signals from global navigation satellite systems2 3 gnss enabling us to track the non steady surface motion of the subducting and overriding plates before during and after the largest events4 6 here we use a recently developed trajectory modelling approach7 that is designed to isolate secular tectonic motions from the daily gnss time series to show that the 2010 maule chile moment magnitude 8 8 and 2011 tohoku oki japan moment magnitude 9 0 earthquakes were preceded by reversals of 4 8 millimetres in surface displacement that lasted several months and spanned thousands of kilometres modelling of the surface displacement reversal that occurred before the tohoku oki earthquake suggests an initial slow slip followed by a sudden pulldown of the philippine sea slab so rapid that it caused a viscoelastic rebound across the whole of japan therefore to understand better when large earthquakes are imminent we must consider not only the evolution of plate interface frictional processes but also the dynamic boundary conditions from deeper subduction processes such as sudden densification of metastable slab

10be imaging of sediment accretion and subduction along the northeast japan and costa rica convergent margins sediment accretion and subduction at convergent margins play an important role in the nature of hazardous interplate seismicity the seismogenic zone and the subduction recycling of volatiles and continentally derived materials to the earth s mantle identifying and quantifying sediment accretion essential for a complete mass balance across the margin can be difficult seismic images do not define the processes by which a prism was built and cored sediments may show disturbed magnetostratigraphy and sparse biostratigraphy this contribution reports the first use of cosmogenic 10be depth profiles to define the origin and structural evolution of forearc sedimentary prisms biostratigraphy and 10be model ages generally are in good agreement for sediments drilled at deep sea drilling project site 434 in the japan forearc and support an origin by imbricate thrusting for the upper section forearc sediments from ocean drilling program site 1040 in costa rica lack good fossil or paleomagnetic age control above the decollement low and homogeneous 10be concentrations show that the prism sediments are older than 3 4 ma and that the prism is either a paleoaccretionary prism or it formed largely from slump deposits of apron sediments low 10be in costa rican lavas and the absence of frontal accretion imply deeper sediment underplating or subduction erosion

denudation rate changes along a fast eroding mountainous river with slate headwaters in taiwan from 10 be meteoric 9 be ratios

geodetic constraints on afterslip characteristics following the march 9 2011 sanriku oki earthquake japan 1 a magnitude 7 3 foreshock occurred at the subducting pacific plate interface on march 9 2011 51 h before the magnitude 9 0 tohoku earthquake off the pacific coast of japan we propose a coseismic and postseismic afterslip model of the magnitude 7 3 event based on a global positioning system network and ocean bottom pressure gauge sites the estimated coseismic slip and afterslip areas show complementary spatial distributions the afterslip distribution is located up dip of the coseismic slip for the foreshock and northward of hypocenter of the tohoku earthquake the slip amount for the afterslip is roughly consistent with that determined by repeating earthquake analysis carried out in a previous study the estimated moment release for the afterslip reached magnitude 6 8 even within a short time period of 51h a volumetric strainmeter time series also suggests that this event advanced with a rapid decay time constant compared with other typical large earthquakes

catchment wide weathering and erosion rates of mafic ultramafic and granitic rock from cosmogenic meteoric 10be 9be ratios abstract quantifying rates of weathering and erosion of mafic rocks is essential for estimating changes to the oceans alkalinity budget that plays a significant role in regulating atmospheric co2 levels in this study we present catchment wide rates of weathering erosion and denudation measured with cosmogenic nuclides in mafic and ultramafic rock we use the ratio of the meteoric cosmogenic nuclide 10be deposited from the atmosphere onto the weathering zone to stable 9be a trace metal released by silicate weathering we tested this approach in stream sediment and water from three upland forested catchments in the north west czech republic the catchments are underlain by felsic granite mafic amphibolite and ultramafic serpentinite lithologies due to acid rain deposition in the 20th century the waters in the granite catchment exhibit acidic ph whereas waters in the mafic catchments exhibit neutral to alkaline ph values due to their acid buffering capability the atmospheric depositional 10be flux is estimated to be balanced with the streams dissolved and particulate meteoric 10be export flux to within a factor of two we suggest a correlation method to derive bedrock be concentrations required as an input parameter which are highly heterogeneous in these small catchments derived earth surface metrics comprise 1 denudation rates calculated from the 10be 9be ratio of the reactive be meaning sorbed to mineral surfaces range between 110 and 185 t km 2 y 1 40 and 70 mm ky 1 these rates are similar to denudation rates we obtained from in situ cosmogenic 10be in quartz minerals present in the bedrock or in quartz veins in the felsic and the mafic catchment 2 the degree of weathering calculated from the fraction of 9be released from primary minerals as a new proxy is about 40 50 in the mafic catchments and 10 in the granitic catchment lastly 3 erosion rates were calculated from 10be concentrations in river sediment and corrected for sorting and dissolved loss these amount to 50 of denudation rates from 10be 9be in the mafic and ultramafic catchments the remainder being mass loss in the dissolved form by weathering in contrast erosion comprises most of the mass loss in the granitic catchment these first results are encouraging given that we find overall good agreement between in situ and meteoric cosmogenic methods that our denudation rates are in the range of those published for middle european river catchments and that degrees of weathering are as expected for these diverse lithologies this method allows quantifying rates of erosion and weathering in mafic rock over the time scale of weathering that are unlike in situ cosmogenic 10be independent from the presence of quartz 10be 9be therefore offers to quantify earth surface processes in a wide range of landscapes underlain by mafic rock rates that are of high importance for exploring climate weathering feedbacks but that have been inaccessible to date

modeling the foreshock sequence prior to the 2011 mw9 0 tohoku japan earthquake 1 the 2011 mw9 0 tohoku earthquake japan was preceded by a 2 day long foreshock sequence initiated by a mw7 3 earthquake we analyze this foreshock sequence with the aim of detecting possible aseismic deformation transients that could have driven its evolution continuous broad band recordings at f net stations are processed to identify as exhaustive a set of mjma 1 2 earthquakes as possible we moreover directly quantify with these recordings the changes in detection level associated with changes in seismic or environmental noise this earthquake data set is then modeled to show that the whole sequence can be readily explained without the need to invoke aseismic transients the observation of a 3 hour long low frequency noise increase concurrent with an apparent migration of seismicity toward the epicenter of the impending mw9 0 mega thrust earthquake however suggests that some premonitory slip could have played a role in loading the asperity which failure initiated the mw9 0 shock we thus propose that this aseismic slip if it really existed had only a minor role in triggering and southward displacing the foreshock sequence as compared to earthquake interaction mechanisms that allow earthquakes to trigger one another

temporal variation of intermediate depth earthquakes around the time of the m9 0 tohoku oki earthquake author s delbridge bg kita s uchida n johnson cw matsuzawa t burgmann r abstract 2017 american geophysical union all rights reserved the temporal evolution of intermediate depth seismicity before and after the 2011 m9 0 tohoku oki earthquake reveals interactions between plate interface slip and deformation in the subducting slab we investigate seismicity rate changes in the upper and lower planes of the double seismic zone beneath northeast japan using both a statistic approach and a temporal epidemic type aftershock sequence model we do not observe an anomalous precursory increase in intermediate depth earthquake activity preceding the mainshock however following the mainshock we observe a rate increase for the intermediate depth earthquakes in the upper plane the average ratio of upper plane to lower plane activity and the mean deep aseismic slip rate both increased by factor of 2 an increase of downdip compression in the slab resulting from coseismic and postseismic deformation enhanced seismicity in the upper plane which is dominated by events accommodating downdip shortening from plate unbending

holocene environmental and climatic change in the northern great plains as recorded in the geochemistry of sediments in pickerel lake south dakota the sediments in pickerel lake northeastern south dakota provide a continuous record of climatic and environmental change for the last 12000 yr sediments deposited between 12 and 6 ka radiocarbon show extreme variations in composition oxygen and carbon isotopic composition of bulk carbonate carbon isotopic composition of organic matter and magnetic susceptibility these variations re ect changes in sources of moisture regional vegetation types precipitation evaporation balance ground and surface water in ux water residence time erosion lake productivity water level and water temperature the total carbonate content of late pleistocene sediments steadily increased from 20 at the base of the core to as much as 80 in sediments deposited between 11 and 9 ka by about 8 ka the total carbonate content of the sediments had declined to about 40 where it remained with little variation for the past 8 kyr suggesting relatively stable conditions there are marked increases in values of d13c and d18 oi n bulk carbonate and d13c of organic matter in sediments deposited between 10 and 6 ka as evaporation increased and the vegetation in the watershed changed from forest to prairie this shift toward more 18o enriched carbonate may also re ect a change in source or seasonality of precipitation during this early holocene interval the organic carbon oc content of the sediments remained relatively low 2 3 but then increased rapidly to 4 5 between 7 and 6 ka re ecting the rapid transition to a prairie lake the oc content uctuates slightly between 4 and 6 in sediments deposited over the past 6 kyr like oc and total carbonate most variables measured show little variation in the 13 m of sediment deposited over the past 6 kyr particularly when compared with early holocene variations although the magnetic susceptibility of this upper 13 m of sediment is generally low 10 si units the upper six meters of the section is marked by striking 1 m cycles ca 400 500 yr periodicity in susceptibility these cycles are interpreted as being due to variations in the in ux of eolian detrital clastic material century scale cyclic variations in di erent proxy variables for aridity and eolian activity from sediments deposited over the past 2000 yr in other lakes in the northern great plains as well as in sand dune activity suggest that aridity cycles were the dominant feature of late holocene climate of the northern great plains 2000 elsevier

erosion of the eastern united states observed with 10be the problem of identifying areas of accelerated erosion in a dynamic landscape is complicated the limited history of sediment yield measurements makes this task difficult even if geomorphic evidence is available beryllium 10 a cosmogenic isotope produced by cosmic rays interacting with the earth s atmosphere and surface has chemical and physical properties that make it useful as a tracer for erosion and sediment transport processes the rarity of the stable isotope 9be allows 10be to be detected with accelerator mass spectrometry in natural materials at extremely low levels backgrounds for rocks and sediments below 105 atom per g are now attainable a value to be compared with an average deposition rate of 1 3 106 atom cm 2 yr 1 the affinity of be for the components of soil and sediment is sufficiently high that it is effectively immobilized on contact thereby allowing 10be to function as a tracer of sediment transport to a good approximation all the 10be transport out of a drainage basin is on the sediment leaving it the number of 10be atoms passing the gauging station can be determined by measuring the concentration of the isotope in the sediment if the annual sediment load is known the ratio of the 10be carried from the basin by the sediment to that incident upon it called the erosion index has been determined for 48 drainage basins within the same physiographic province which allows them to be reasonably compared all of which have sediment yield data basins located in the atlantic coastal plain have an average index of 0 3 with the maximum observed being 0 9 basins located between the fall line and the mountains a region called the piedmont have an average value of 2 2 with individual values ranging from 0 6 to 6 7 this marked difference is thought to result from two centuries of farming on land of moderate gradient basins in the highland regions reflect local conditions with low indices for those in grass and timber and high indices associated with destructive land use the data allow an estimate of the erosion index for the pre colonial piedmont which then allows the pre colonial sediment yield to be calculated a number of basins have also been examined world wide with similar conclusions derived an important deviation from the rule is noted for rivers that erode large regions of loess such as the mississippi hwang ho and yangtze large aeolian deposits were laid down during the ice age in these basins deposits that brought inherited 10be with them and that are easily eroded

meteoric cosmogenic beryllium 10 adsorbed to river sediment and soil applications for earth surface dynamics abstract rainfall scavenges meteoric cosmogenic 10be from the atmosphere 10be falls to the earth s surface where it binds tightly to sediment particles in non acidic soils over the life span of those soils as such meteoric 10be has the potential to be an excellent geochemical tracer of erosion and stability of surfaces in a diverse range of natural settings meteoric 10be has great potential as a recorder of first order erosion rates and soil residence times even though this tracer was first developed in the late 1980s and showed great promise as a geomorphic tool it was sidelined in the past two decades with the rise of the sister nuclide in situ 10be which is produced at a known rate inside quartz minerals since these early days substantial progress has been made in several areas that now shed new light on the applicability of the meteoric variety of this cosmogenic nuclide here we revisit the potential of this tracer and we summarize the progress 1 the atmospheric production and fallout is now described by numeric models and agrees with present day measurements and paleo archives such as from rain and ice cores 2 short term fluctuations in solar modulation of cosmic rays or in the delivery of 10be are averaged out over the time scale soils accumulate 3 in many cases the delivery of 10be is not dependent on the amount of precipitation 4 we explore where 10be is retained in soils and sediment 5 we suggest a law to account for the strong grain size dependence that controls adsorption and the measured nuclide concentrations and 6 we present a set of algebraic expressions that allows calculation of both soil or sediment ages and erosion rates from the inventory of meteoric 10be distributed through a vertical soil column the mathematical description is greatly simplified if the accumulation of 10be is at a steady state with its export through erosion in this case a surface sample allows for the calculation of an erosion rate explored further this approach allows calculation of catchment wide erosion rates from river sediment similar to the approach using 10be produced in situ in contrast to the in situ 10be approach however these analyses can be performed on any sample of fine grained material even where no quartz minerals are present therefore this technique may serve as a tool to date sediment where no other chronometer is available to track particle sources and to measure earth surface process rates in soil suspended river sediment and fine grained sedimentary deposits

sediment transit time and floodplain storage dynamics in alluvial rivers revealed by meteoric 10be quantifying the time scales of sediment transport and storage through river systems is fundamental for understanding weathering processes biogeochemical cycling and improving watershed management but measuring sediment transit time is challenging here we provide the first systematic test of measuring cosmogenic meteoric beryllium 10 10bem in the sediment load of a large alluvial river to quantify sediment transit times we take advantage of a natural experiment in the rio bermejo a lowland alluvial river traversing the east andean foreland basin in northern argentina this river has no tributaries along its trunk channel for nearly 1 300 km downstream from the mountain front we sampled suspended sediment depth profiles along the channel and measured the concentrations of 10bem in the chemically extracted grain coatings we calculated depth integrated 10bem concentrations using sediment flux data and found that 10bem concentrations increase 230 from upstream to downstream indicating a mean total sediment transit time of 8 4 2 2 kyr bulk sediment budget based estimates of channel belt and fan storage times suggest that the 10bem tracer records mixing of old and young sediment reservoirs on a reach scale 10bem transit times are shorter where the channel is braided and superelevated above the floodplain and longer where the channel is incised and meandering suggesting that transit time is controlled by channel morphodynamics this is the first systematic application of 10bem as a sediment transit time tracer and highlights the method s potential for inferring sediment routing and storage dynamics in large river systems

a mediterranean perspective on 10be sedimentation and climate around the matuyama brunhes boundary les liaisons dangereuses abstract the 10be 9be ratio is commonly employed as a tool for establishing the stratigraphic position of paleomagnetic excursions and reversals whenever the traditional paleomagnetic approach fails to provide conclusive results in particular it is held that 10be production rates in the atmosphere depend on the strength of the earth s magnetic field and the fallout and deposition of cosmogenic beryllium at the surface happen on a very short time scale however investigations performed on terrestrial and marine successions demonstrate that the 10be record and the paleomagnetic signal are often asynchronous mechanisms that control the conveyance and deposition of cosmogenic 10be to the seafloor are still ambiguous and poorly documented here we discuss the dynamics of 10be in a central mediterranean marginal marine depositional scenario characterized by a pervasive terrigenous influx our data show that a very close correlation exists between 10be concentrations and the local proxy of rainfall rates and regimes pollen indicating that a considerable 10be transport from the mainland may occur in response to the remobilization of terrestrial reservoirs during periods of increased runoff superimposed is a dynamic oceanographic setting that further controls the preservation potential of 10be at the bottom in terms of changing water chemistry and or composition of the sedimentary flux to the seafloor results of our investigation suggest that in particular environmental and depositional settings the interplay between climate terrigenous yield and oceanography may jeopardize the sedimentary depiction of the meteoric 10be contribution thus challenging the use of 10be for tracking the stratigraphic position of geomagnetic reversals

soil formation and weathering in a permafrost environment of the swiss alps a multi parameter and non steady state approach spatially discontinuous permafrost conditions frequently occur in the european alps how soils under such conditions have evolved and how they may react to climate warming is largely unknown this study focuses on the comparison of nearby soils that are characterised by the presence or absence of permafrost active layer thickness 2 3 m in the alpine tundra and subalpine forest range of the eastern swiss alps using a multi method geochemical and mineralogical approach moreover a new non steady state concept was applied to determine rates of chemical weathering soil erosion soil formation soil denudation and soil production long term chemical weathering rates soil formation and erosion rates were assessed by using immobile elements fine earth stocks and meteoric 10be in addition the weathering index k ca ti the amount of fe and al oxyhydroxides and clay minerals characteristics were considered all methods indicated that the differences between permafrost affected and non permafrost affected soils were small furthermore the soils did not uniformly differ in their weathering behaviour a tendency towards less intense weathering in soils that were affected by permafrost was noted at most sites weathering rates the proportion of oxyhydroxides and the weathering stage of clay minerals were lower in permafrost soils in part erosion rates were higher at the permafrost sites and accounted for 79 97 of the denudation rates in general soil formation rates 8 8 86 7 t km2 y were in the expected range for alpine soils independent of permafrost conditions it seems that the local microenvironment particularly vegetation and subsequently soil organic matter has strongly influenced denudation rates as the climate has varied since the beginning of soil evolution the conditions for soil formation and weathering were not stable over time soil evolution in high alpine settings is complex owing to among others spatio temporal variations of permafrost conditions and thus climate this makes predictions of future behaviour very difficult this article is protected by copyright all rights reserved

inferring the coseismic and postseismic stress changes caused by the 2004 mw 6 parkfield earthquake from variations of recurrence times of microearthquakes 1 kinematic models of coseismic stress inverted from ground motion data do not usually find good correlation between the location of aftershocks and high stress patches in particular numerous earthquakes are recorded in areas of the fault where the stress decreases however most of coseismic slip distributions have limited spatial resolution typically not better than 1 km here we investigate the stress changes produced by the 2004 mw 6 parkfield earthquake on and near its rupture zone at the scale of magnitude 2 earthquake asperities approximately tens of meters after relocating earthquakes in this zone between 1984 and 2007 we form repeating highly similar earthquake sequences and study how the quasiperiodicity of occurrence at each sequence observed during the 20 years preceding the 2004 main shock is perturbed by this event we apply a simple model of the seismic cycle to infer the coseismic and postseismic stresses experienced by the repeatedly failing asperities despite being spatially sparse these stress distributions have resolutions only limited by the typical scale of an asperity we propose that the high spatial variability of the seismicity patterns following the mw 6 earthquake results from an heterogeneous coseismic stress field the emergence of the omori utsu law observed at large scale greater than kilometers at parkfield is simply the outcome of averaging such quasi deterministic patterns over many sequences the fact that the coseismic stress can significantly change over distances of the order of 100 m adds credence to the hypothesis that earthquake rupture is intrinsically very heterogeneous

relative variations in geomagnetic intensity from sedimentary records the past 200 000 years abstract eighteen records of relative paleointensity from marine sediments have been compiled in order to retrace the global changes in geomagnetic intensity during the past 200 kyr before dealing with any other source of noise we focused on problems inherent to the depth versus time correlations the accuracy and resolution of dating mostly deduced from isotopic stratigraphy were identified as significant factors of distortion we found also that different time scales have been used by authors after readjustment with respect to the same time scale the records were stacked together and the statistical significance of the results tested by a bootstrap technique seventeen records shown to be coherent were combined into a synthetic curve defined as sint 200 other stacks combining various subsets of data were found to be identical to sint 200 except for changes in dispersion in fact the dispersion around sint 200 could be reduced further by improving the correlations without violating the stratigraphy a procedure which at least for some records emphasizes the need for more detailed depth time correlations another characteristic emerging from the results is that paleointensity features as short as 10 kyr are observed between 120 200 ka and can thus in principle be resolved however subsequent refinement is still necessary for this period which is documented by fewer records than the following 120 kyr finally we compared sint 200 with the records from the labrador sea and the lac du bouchet ldb both of which rely mostly on 14c chronology the two records show satisfactory agreement with sint 200 when transferred with respect to the age model established by correlating their 18o labrador and susceptibility features ldb with the 18o reference record the offset of 7 kyr at 40 ka measured in both cases between the 14c and 18o ages is higher than the value deduced from a recent model of a geomagnetic field control of 14c production 1 but is not inconsistent with recent u th dates

a test of the cosmogenic 10be meteoric 9be proxy for simultaneously determining basin wide erosion rates denudation rates and the degree of weathering in the amazon basin we present an extensive investigation of a new erosion and weathering proxy derived from the 10be meteoric 9be stable ratio in the amazon river basin this new proxy combines a radioactive atmospheric flux tracer meteoric cosmogenic 10be with 9be a trace metal released by weathering results show that meteoric 10be concentrations 10be and 10be 9be ratios increase by 30 from the andes to the lowlands we can calculate floodplain transfer times of 2 30 kyr from this increase intriguingly however the riverine exported flux of meteoric 10be shows a deficit with respect to the atmospheric depositional 10be flux most likely the actual area from which the 10be flux is being delivered into the mainstream is smaller than the basin wide one despite this imbalance denudation rates calculated from 10be 9be ratios from bed load suspended sediment and water samples from amazon rivers agree within a factor of 2 with published in situ 10be denudation rates erosion rates calculated from meteoric 10be measured from depth integrated suspended sediment samples agree with denudation rates suggesting that grain size induced variations in 10be are minimized when using such sampling material instead of bed load in addition the agreement between erosion and denudation rates implies minor chemical weathering intensity in most amazon tributaries indeed the be specific weathering intensity calculated from mobilized 9be comprising reactive and dissolved fractions that are released during weathering is constant at approximately 40 of the total denudation from the andes across the lowlands to the amazon mouth therefore weathering in the amazon floodplain is not detected

migration of early aftershocks following the 2004 parkfield earthquake a significant number of the early aftershocks following large shallow earthquakes are missing in existing earthquake catalogues an analysis of the waveforms of 3 647 relocated earthquakes along the parkfield section of the san andreas fault reveals 11 times more aftershocks within three days of the 2004 parkfield earthquake than listed in a standard catalogue large shallow earthquakes are immediately followed by numerous aftershocks a significant portion of these events is missing in existing earthquake catalogues mainly because seismicity after the mainshock can be masked by overlapping arrivals of waves from the mainshock and aftershocks1 2 3 4 however recovery of the missing early aftershocks is important for understanding the physical mechanisms of earthquake triggering2 3 4 and for tracking postseismic deformation around the rupture zone associated with the mainshock5 6 7 here we use the waveforms of 3 647 relocated earthquakes8 along the parkfield section of the san andreas fault as templates9 10 to detect missing aftershocks within three days of the 2004 magnitude 6 0 parkfield earthquake we identify 11 times more aftershocks than listed in the standard catalogue of the northern california seismic network we find that the newly detected aftershocks migrate in both along strike and down dip directions with logarithmic time since the mainshock consistent with numerical simulations of the expansion of aftershocks caused by propagating afterslip11 12 the cumulative number of early aftershocks increases linearly with postseismic deformation in the first two days supporting the view that aftershocks are driven primarily by afterslip13 14

10 be and delta 2 h in polar ice cores as a probe of the solar variability s influence on climate and discussion by using the technique of accelerator mass spectrometry it is now possible to measure detailed profiles of cosmogenic cosmic ray produced 10 be in polar ice cores recent work has demonstrated that these profiles contain information on solar activity via its influence on the intensity of galactic cosmic rays arriving in the earth s atmosphere it has been known for some time that as a result of temperature dependent fractionation effects the stable isotope profiles delta 2 o and delta 2 h in polar ice cores contain palaeoclimate information thus by comparing the 10 be and stable isotope profiles in the same ice core one can test the influence of solar variability on climate and this independent of possible uncertainties in the absolute chronology of the records we present here the results of such a comparison for two antarctic ice cores one from the south pole covering the past ca 1000 years and one from dome c covering the past ca 3000 years

change in seismicity along the japan trench 1990 2011 and its relationship with seismic coupling we investigate the temporal evolution of the background seismicity rate related to the subduction of the pacific plate in northeast japan at latitudes 34o to 42o for the 1 1 1990 9 3 2011 period two declustering methods are used to identify robust features we find that the dominant behaviour is a lowering down of activity especially in the northern half of our studied area where changes appear related to the cycle of m7 5 earthquakes in particular the 1968 tokachi and the 1994 sanriku earthquakes acceleration of background seismicity is observed offshore the kanto region and could mark a long term decoupling of the pacific and the philippine sea plates over a 100 km long segment along the sagimi trough which cannot be simply explained by the earthquake cycle model our analysis further suggests that changes in background seismicity are plausibly related to changes in seismic coupling and thus further strengthens the recent observation that seismic coupling does vary at the time scales of tens of years for the japanese subduction zone

particle trajectories on hillslopes implications for particle age and 10be structure many geomorphic systems act as conveyor belts onto which material is loaded at a particular rate and is transported in one direction toward another system that serves as a sink as the material travels it ages it changes in grain size it accumulates cosmogenic radionuclides it adsorbs or releases nutrients and it weathers here i address the hillslope conveyor as many geochemical processes are depth dependent the depth history of a particle becomes important to know i calculate soil particle trajectories in the horizontal depth plane and address three cases one in which horizontal speeds decline exponentially with depth a second in which they are uniform with depth and a third in which horizontal speeds are also uniform but all profile values are vertically well mixed vertical speeds are governed by continuity in an incompressible medium and by the boundary condition of zero vertical particle speed at the soil surface particle trajectories must therefore become surface parallel at the surface knowledge of soil particle trajectories allows calculation of residence times and concentration profiles of 10be in the soil the results inform strategies for interpretation of nuclide concentrations in soils and stream sediments and for inference of transport rate profiles in all steady cases the particle age and 10be structure is uniform with distance from the divide when significant vertical gradients in horizontal speed occur the patterns of particle age and of 10be concentration are dominated by the depth scale of the transport process in unmixed cases the particle age and 10be concentration in near surface samples can greatly exceed the vertically averaged values reflecting the fact that the vertical speeds of particles slow dramatically as they near the surface in cases in which horizontal speed varies significantly with depth the vertically averaged concentration of 10be within the soil can significantly under predict the mean 10be concentration of sediment delivered to the channel proper averaging requires weighting by particle speed these results provide the backdrop for addressing chemical evolution of soil on a hillslope