excess 210pb inventories and fluxes along the continental slope and basins of the gulf of papua 1 sediment samples were collected from continental slopes and marginal basins in the gulf of papua and analyzed for excess 210pb to elucidate transport processes of fine grained particles to this region estimated excess 210pb fluxes of 1 0 12 8 dpm cm 2 a 1 were derived from measured seabed inventories highest sediment accumulation rates 0 28 0 35 cm a 1 were measured along the northeastern shelf edge and they decrease in seaward directions and along isobaths to the southwest the excess 210pb flux could result from either focused deposition of high 210pb activity sediments from the continental shelf and upper slope or scavenging of 210pb brought landward from deep sea waters this sediment flux is concentrated in the northeastern gulf of papua where the shelf is narrow and calcium carbonate contents are lowest analysis of sedimentary fabric and 210pb distributions in cores suggests sediment delivery to the slope occurs on a 100 year timescale as both diffuse hemipelagic deposition as well as turbidity flows the flux of sediment in turbidity flows is not well constrained but may be producing additional deep sea accumulation in the moresby trough as well as export from the study area

the diffusion and telegraph equations in diagenetic modelling this paper considers the practical aspects of differentiating between the solutions of the diffusion and telegraph equations when they are used to model molecular diffusion in sediment pore waters and the diffusive bioturbation of solids if molecular diffusion is the only transport mechanism in pore water then the results from a simple random walk model coupled to the hydrodynamic or kinetic theories of diffusion indicate that the solute profiles predicted by these two equations differ measurably only for periods up to 10 sup minus 10 s after the introduction of a transient and for spatial scales less than 10 sup minus 6 cm in addition the distinct propagating front predicted by the telegraph equation moves so fast and is so attenuated as to be unmeasurable in this situation the telegraph equation offers no practical advantage over the diffusion equation for the description of diagenetic pore water profiles these findings also hold when advection due to burial and chemical reaction are included in the model the time scales associated with bioturbation of solids are sufficiently long compared to normal sampling times that the profiles of some transients both in deep sea and near shore sediments should exhibit behavior characteristic of the telegraph equation if mixing is diffusive local

analytical expressions for transient specific yield and shallow water table drainage 1 new closed form expressions are introduced to capture the dependence of specific yield on time and depth to water table the expressions allow the user to convert observations of water table fluctuations to volumes of water released from storage in a shallow water table aquifer whereas a linear relationship between water table fluctuations and released volumes holds for a deep water table aquifer this relationship is nonlinear for shallow water table aquifers the dependence of specific yield on time stems from the slow drainage of soil water from pores above the water table the new expressions allow determination of transient specific yield and time to drain the soil water profile for a given water table fluctuation if the time step in a numerical groundwater model is longer than the time for limiting specific yield then a constant time independent specific yield can be justifiably adopted the new expressions are easy to use and require knowledge of soil hydraulic properties which are readily available from soil water retention data and surveys

experimental tests for particle size dependent bioturbation in the deep ocean the potential for particle size dependent bioturbation rates was experimentally tested at 1 240 m in the santa catalina basin eastern pacific spherical glass bead tracers in five size classes 816 17 31 32 62 63 125 and 126 420 m were spread over the sediment surface and tube cored 997 d later downcore concentrations of glass beads were enumerated in each of the five size categories and page s l test was used to test the null hypothesis of equal vertical penetration of all size classes of tracer in all cores the null hypothesis was rejected finer tracers penetrated deeper into the sediment in two of the three cores vertical biodiffusivities were computed from concentration profiles of downcore tracers these also showed size dependence with biodiffusivities ranging from 1 cm2 yr for the 8 1 6 pm fraction to 0 1 cm2 yr for the 1 25 420 pm size class these data demonstrate that vertical bioturbation rates are particle size dependent in santa catalina basin the likely cause is preferential ingestion and downward transport of fine particles by deposit feeders

quantifying fault zone activity in arid environments with high resolution topography 1 high resolution airborne laser swath mapping alsm topography illuminates active faulting with unprecedented clarity we contrast alsm topography of two dextral faults in arid regions of california with slip rates that differ by an order of magnitude the lenwood fault with rate of 1 mm yr and the clark fault a strand of the san jacinto fault with net slip rate 10 mm yr visualization of alsm data reveals abundant fault scarps and deflected channels that when reconstructed can yield powerful slip constraints though many of these features may also be detected in existing aerial photography these data are limited by stereo depth resolution and fixed illumination angle

evidence for prehistoric earthquakes on the superstition hills fault from offset geomorphic features offset geomorphic features along the superstition hills fault show evidence for at least one slip event prior to the 1987 surface rupture and possibly as many as four to five earlier prehistoric earthquakes we documented several geomorphic features that appeared offset by multiple events by making detailed topographic maps offset features were abundant along reaches of the fault with high topographic relief and large displacement slip distribution for the penultimate event as recorded by offset rills streams and shrub coppice dunes is very similar to the slip distribution from the 1987 earthquake through april 1988 this similarity may prove to be fortuitous if afterslip from the 1987 event continues to increase the total slip for this earthquake but if afterslip associated with the 1987 event ceases in the near future then the past two earthquakes were nearly identical in slip and the superstition hills fault may be expected to produce characteristic earthquakes of roughly magnitude 6

chlorophyll a and pheopigments as tracers of labile organic carbon at the central equatorial pacific seafloor high rates of primary production and fast sinking rates lead to the deposition of phytodetritus and highly reactive organic matter to the sediments of the central equatorial pacific these substances are responsible for driving important chemical fluxes and fueling benthic organisms chloropigments have proven useful as tracers of similar highly reactive organic carbon components in lacustrine and nearshore marine sediments in this study we investigate the degradation of chlorophyll a and pheopigments a at four abyssal sites on the jgofs equatorial pacific transect along 140 w and explore the usefulness of these chloropigments as tracers of the most reactive component of the deep sea particulate organic carbon poc rain first order reaction rate constants k 1 75 yr 1 half life 3 250 d and relative reactivities chlorophyll a allomer and pheophorbide a pheophytin a derived from most of the sedimentary profiles are similar to those found in laboratory and other field lake and coastal marine studies however in some profiles the rate constants determined by fitting data below 0 5 cm are slower by up to 3 orders of magnitude despite an apparent abundance of bacteria macrofauna and porewater oxygen model results assuming multi g kinetics suggest that these chloropigments degrade as two components one which accounts for at least 99 of the degradation and 11 57 of the sediment inventory degrades with a half life of 4 120 days the other component degrades with a half life of up to 440 years these results suggest that some otherwise labile poc may be protected and escape rapid degradation near the sediment water interface if phytodetritus is deposited continuously throughout the year our model calculated chlorophyll a fluxes indicate that it could account for 25 100 of the annual poc flux at sites close to the equator

rapid bioturbation in equatorial pacific sediments evidence from excess 234th measurements in order to evaluate bioturbation in equatorial pacific sediments profiles of excess 234th were measured in cores collected during november and december 1992 at six abyssal sites along the jgofs equatorial pacific 140 w transect from 5 s to 9 n excess 234th half life 24 1 days was detected at all sites mean inventories ranged from a low of 0 25 dpm cm 2 at 9 n to a high of 2 6 dpm cm 2 at 2 n eddy diffusive models of the excess 234th profiles suggest that on 100 day timescales particle mixing is slow at 5 s and 2 s eddy diffusion coefficient db 0 4 cm2 year 1 faster at 0 and 2 n db 0 34 4 8 cm2 year 1 and fastest at 5 n db 4 7 11 cm2 year 1 at 9 n 234th is found almost entirely in the upper 5 mm of the seabed and db values are 0 1 cm2 year 1 db values generally increase as poc flux increases although the linear relationship r2 0 334 p 0 365 displays considerable scatter however if the only sites included in the regression are those where 234th profiles were measured in at least two core sets i e 0 2 n 5 n and 9 n the linear regression improves substantially r2 0 754 p 0 0012 these results suggest that measurements on a single core may not fully characterize the sediment mixing regime in a particular region and highlight the need for multiple samples from an individual site thorium 234 db values at 5 s 2 s and 9 n are in rough agreement with published db values calculated from the profiles of intermediate half life radioisotopes such as 210pb and 137cs in open ocean abyssal sediments however at 0 2 n and 5 n 234th db values are as much as an order of magnitude greater than published 210pb db values this phenomenon has been observed in other marine environments and may result from age dependent mixing non steady state mixing or a combination of the two processes particle mixing in cores collected at 5 s and 5 n appears to be best described as a largely eddy diffusive process however in cores collected at 2 s 0 2 n and 9 n non local mixing processes appear to affect 15 30 of the excess 234th inventory at these sites non local mixing appears to transport recently deposited material at least 3 4 cm below the sediment water interface within 100 days of its arrival at the seafloor the combination of rapid biodiffusive mixing and non local transport allows recently deposited reactive biogenic debris to be rapidly mixed into the seabed this may affect a wide range of diagenetic processes including oxygen consumption dissolution of biogenic debris and organic carbon remineralization models of early diagenesis in deep sea sediments may need to incorporate both non diffusive transport terms and rapid biodiffusive mixing of recently deposited particles

constraining recent fault offsets with statistical and geometrical methods example from the jasneuf fault western alps france we propose two new approaches regarding recent fault offset measurements by studying the seismogenic potential of the jasneuf fault the ne trending right lateral strike slip jasneuf fault is the southwestern extension of the belledonne fault system in the vercors massif this fault which is located in an intraplate domain does not show strongly associated seismicity but displays morphological anomalies that are related to recent faulting right lateral offset of late cenozoic cliffs recent talwegs and post ganz scarps the two methods that we use to quantify fault slip are as follows 1 recursive measurements of stream offsets are conducted this analysis reveals that a stream network can display characteristic distances between streams that can be mistakenly interpreted as long term cumulative fault offsets a comparison of the apparent stream offset values and stream spacing values is necessary to identify the true offsets 2 we propose a new method that enables us to determine the fault offset and kinematics by using recursive measurements of topographic apparent offsets to counter the lack of morphologic features that are used to determine piercing points or lines this method enables us to define each possible slip vector for numerous artificial piercing points along a fault the slip vector that is shared by these piercing points is the true slip vector by applying these methodologies we determine that the jasneuf fault has accumulated slip since the messinian which corresponds to an average slip rate of 0 13 0 03 mm year the extension of the fault is poorly constrained nevertheless if we do not consider the potential aseismic creep slip component of the faulting we calculate that this fault could generate mw 5 7 earthquakes every similar to 500 years according to wells and coppersmith s scaling laws and by assuming that the faulting is limited to the sedimentary cover and the vercors plateau c 2016 elsevier b v all rights reserved

accumulation and biological mixing of peru margin sediments abstract rates of sediment accumulation and biological particle mixing in eight cores from the peru shelf have been estimated by application of uranium series disequilibrium techniques and radiocarbon dating activities of 210pb 226ra 234th and 238u have been determined in closely spaced intervals in each sediment core biological particle mixing coefficients were determined via a two box advection diffusion steady state mixing model based on the distribution profiles of excess 210pb and in some cases excess 234th activities the sedimentation rates estimated were in the order of a few millimeters yr except for cores enriched in phosphatic components which displayed rates a few orders of magnitude slower bioturbation was significant in most cores studied with the exception of one core collected from within the middle of the oxygen minimum zone estimated biological mixing coefficients were in the order of 100 101 cm2 yr 1 for the surface mixed layer and 10 1 100 cm2 yr 1 for the layer below sediment slumping appears to have affected the 210pb distribution of two or three of our cores

bioturbation short lived radioisotopes and the tracer dependence of biodiffusion coefficients bioturbation refers to the mixing of sediment particles resulting from benthic faunal activity it is the dominant particle mixing process in most marine sediments and exerts an important control on diagenetic processes in models bioturbation is usually treated as a diffusive process where the biodiffusion coefficient db characterizes the biological mixing intensity biodiffusion coefficients are classically computed by fitting a diffusive model to vertical profiles of particle bound radioisotopes one peculiar observation is tracer dependence db values from short lived tracers tend to be larger than those obtained from long lived tracers from the same site recent theoretical work based on random walk theory and lattice automaton bioturbation simulations labs has suggested that this tracer dependence is simply a model artifact and has concluded that the biodiffusion model is not applicable to the short observational time scales associated with short lived radioisotopes here we have compiled a global dataset of db values obtained from different radiotracers to assess tracer dependence from a data perspective tracer dependence is significant in low mixing environments like slope and deep sea sediments but is not present in intensely mixed coastal areas tracer dependence is absent when the number of mixing events is larger than 20 or the potential length scale is greater than 0 5 cm roughly this comes down to tracer derived db values greater than 2 cm2 yr 1 this condition is met for 68 50 and 8 of published db values obtained from coastal continental slope and abyssal environments respectively these results show that short lived radioisotopes are suitable to quantify biodiffusion mixing in sedimentary environments featuring intense bioturbation

rapid determination of near fault earthquake deformation using differential lidar improved near field measurements of earthquake slip and deformation patterns have the potential for expanding our understanding of fault behavior and the relationship of active faulting to topography current techniques for obtaining these measurements including field observation global navigation satellite systems displacement estimation and optical or radar remote sensing have limitations that can be mitigated by the inclusion of results from differential airborne light detection and ranging lidar analysis of the rupture zone the 2005 airborne lidar survey of the southern san andreas san jacinto and banning faults the b4 survey mapped 1100 km of the most seismically active fault systems in southern california for the purpose of providing a baseline for determining slip from a future earthquake we used the b4 survey to develop a processing algorithm that yields rapid estimates of near fault ground deformation using simultaneous cross correlation of both topography and backscatter intensity from pre earthquake and simulated postearthquake lidar datasets we show robust recovery of the direction and magnitude of an applied synthetic slip of 5 m in the horizontal and 0 5 m in the vertical within our area of study with clear discrimination between areas with and without applied slip we also successfully recovered more complex deformation from a modeled fault stepover in the same study area our results indicate that we should be able to recover slip to accuracies of better than 20 cm in the horizontal and 1 cm in the vertical at a spatial resolution of 15 m for lidar datasets with sample densities as low as 0 5 points m2

regional patterns of bioturbation and iron and manganese reduction in the sediments of the southeastern bering sea regional patterns of iron fe and manganese mn reduction rates across the shelf and slope of the southeastern bering sea as well as the relative importance of these pathways in sedimentary organic matter remineralization were investigated during the spring and summer of 2009 reduction rates of fe and mn were calculated using depth pro les of solid phase iron and manganese oxide concentrations and bioturbation coef cients db determined from pro les of excess 234 th iron reduction was found to be a signi cant pathway for carbon mineralization across the shelf with an average rate of 1 74 mmol m 2 d 1 however fe reduction rates higher than 6 mmol m 2 d 1 were calculated and a signi cant regional pattern was observed with highest rates found on the northern shelf and dropping toward the south and offshore conversely mn oxide reduction was found to be of minor signi cance with low reduction rates in all regions averaging only 0 09 mmol m 2 d 1 across the shelf and accounting for no more than 5 of total carbon oxidation in any region these results indicate that fe oxide reduction is a signi cant pathway for carbon remineralization in the northern and middle shelf regions where organic matter deposition rates and benthic biomass are high additionally this work provides insight into the potential role of sedimentary iron reduction as a source of bioavailable fe in this region

234th and 21pb evidence for rapid ingestion of settling particles by mobile epibenthic megafauna in the abyssal ne pacific particle scavenged 234 th and 210 pb can be used to trace the fate of particulate matter reaching the deep sea floor we used this technique to demonstrate rapid ingestion of particles arriving at the sea floor at a depth of 4 100 m by mobile epibenthic holothuroids abyssocucumis abyssorum and oneirophanta mutabilis excess 234 th and 210 pb activities of sediment trap material detrital aggregates from the sea floor and animal gut contents all were similar while activities of surface sediments top 0 5 mm were considerably lower a simple calculation using the excess 210 pb concentration of two potential food sources sediment trap material and surface sediments shows that 91 of gut content material of a abyssorum must have come from material similar to that found in the sediment trap cups by setting the sediment trap material as age 0 apparent ages of 100 d and 12 13 d were estimated for the aggregates surface sediments and a abyssorum guts respectively the population of a abyssorum at this site could potentially process 0 2 4 of the vertical mass flux m 2 d 1 during the high particle flux period between june and october 1994 the percentage of vertical flux processed could be substantially greater when all of the mobile epibenthic megafauna species are considered

sedimentary processes in the thau lagoon france from seasonal to century time scales as a part of the microbent programme an investigation of the sedimentation framework was carried out at the water sediment interface in the thau lagoon french mediterranean coast two main sites c4 in the middle of the lagoon and c5 near oyster farms were visited six times between december 2001 and may 2003 interface sediments were studied using classical sedimentology parameters radiography rx grain size distribution and analysis of selected radionuclides 234th 7be 210pb 226ra on a century time scale excess 210pb 210pbxs presents classical profiles with an upper mixed layer followed by an exponential decrease of activities to undetectable levels below 20 30 cm at the central site c4 cores seem to register episodic changes in mean grain size presenting recurrently peaks the upper 10 cm of 210pbxs profiles at site c5 exhibit a mixed layer associated with coarser sediments this could be related to biological activity sedimentation rates derived from 210pbxs varied from 0 15 cm y 1 at the edge of the basin to 0 25 cm y 1 at the central site on a seasonal time scale 234th and 7be both show significant variations in activities and in penetration within the sediment bioturbation rates derived from both radionuclides agree well and range between 1 10 cm2 y 1 at site c4 and 1 31 cm2 y 1 at site c5 234th and 7be fluxes at the water sediment interface show too seasonal variations more pronounced for site c5 this latter site presents especially a higher variability that is well marked with season probably in relation with its position near oyster farms

lebensspuren of the bathyal mid atlantic ridge the extent of megafaunal bioturbation was characterised at flat sedimented sites on the mid atlantic ridge mar at 2500 m depth this study investigated the properties of and spatial variation in surficial bioturbation at the mar lebensspuren assemblages were assessed at four superstations either side of the mar and in two different surface productivity regimes north and south of the sub polar front high definition rov videos from these superstations were used to quantify area and abundance of 58 lebensspuren types lebensspuren area was lowest at the sw with 4 12 lebensspuren coverage and the se nw had the greatest area coverage of lebensspuren 9 69 for both all stations except the sw were dominated by epifaunal particularly track style lebensspuren infaunal mounds were more significant in the southern superstations particularly in the sw in terms of lebensspuren assemblage composition all superstations were significantly different from one another which directly corresponded with the composition of lebensspuren forming epifauna lebensspuren assemblages appeared to have been primarily influenced by local scale environmental variation and were independent of detrital flux this investigation presented a novel relationship between lebensspuren and faunal density that conflicted with the traditionally held view of inverse proportionality and suggests that at the mar megafaunal reworking was not the only significant control on lebensspuren assemblages

fault slip and earthquake recurrence along strike slip faults contributions of high resolution geomorphic data article i nfo understanding earthquake eq recurrence relies on information about the timing and size of past eq ruptures along a given fault knowledge of a fault s rupture history provides valuable information on its potential future behavior enabling seismic hazard estimates and loss mitigation stratigraphic and geomorphic evidence of faulting is used to constrain the recurrence of surface rupturing eqs analysis of the latter data sets culminated during the mid 1980s in the formulation of now classical eq recurrence models now routinely used to assess seismic hazard within the last decade light detection and ranging lidar surveying technology and other high resolution data sets became increasingly available to tectono geomorphic studies promising to contribute to better informed models of eq recurrence and slip accumulation patterns after reviewing motivation and background we outline requirements to successfully reconstruct a fault s offset accumulation pattern from geomorphic evidence we address sources of uncertainty affecting offset measure ment and advocate approaches to minimize them a number of recent studies focus on single eq slip distribu tions and along fault slip accumulation patterns we put them in context with paleoseismic studies along the respective faults by comparing coefficients of variation cv for eq inter event time and slip per event and find that a single event offsets vary over a wide range of length scales and the sources for offset variability differ with length scale b at fault segment length scales single event offsets are essentially constant c along fault offset accumulation as resolved in the geomorphic record is dominated by essentially same size large offset in crements and d there is generally no one to one correlation between the offset accumulation pattern constrained in the geomorphic record and eq occurrence as identified in the stratigraphic record revealing the higher resolution and preservation potential of the latter while slip accumulation along a fault segment may be dominated by repetition of large nearly constant offset increments timing of surface rupture is less regular

near field deformation from the el mayor cucapah earthquake revealed by differential lidar large moment magnitude m w 7 continental earthquakes often generate complex multifault ruptures linked by enigmatic zones of distributed deformation here we report the collection and results of a high resolution nine returns per square meter airborne light detection and ranging lidar topographic survey of the 2010 m w 7 2 el mayor cucapah earthquake that produced a 120 kilometer long multifault rupture through northernmost baja california mexico this differential lidar survey completely captures an earthquake surface rupture in a sparsely vegetated region with pre earthquake lower resolution 5 meter pixel lidar data the postevent survey reveals numerous surface ruptures including previously undocumented blind faults within thick sediments of the colorado river delta differential elevation changes show distributed kilometer scale bending strains as large as 10 3 microstrains in response to slip along discontinuous faults cutting crystalline bedrock of the sierra cucapah

comparison of different tracers and methods used to quantify bioturbation during a spring bloom 234 thorium luminophores and chlorophylla rates and types of particle bioturbation were measured before and during the 1993 phytoplankton spring bloom in long island sound u s a bioturbation rates were determined at intervals of 2 weeks using three independent tracers 234th chlorophyllaand luminophores that have different boundary conditions and reaction properties 234th t1 2 24 days is supplied continuously from overlying water the delivery of chlorophylla chl a a non conservative tracer of fresh organic matter having a known degradation rate tracks overlying water productivity and is characterized by non steady state pulses luminophores fluorescent particulate tracers were used in a series of manipulative pulse input experiments under bothin situand laboratory conditions sediment temperature varied from 0 4 to 15 8 c during the measurement period bioturbation was quantified by applying either steady or non steady state biodiffusive bioadvective models that take into account both diffusive transport db and vertical advective transport vb by conveyor belt feeders pulsed inputs of chl aand luminophores demonstrated rapid biogenic burial of surface sediment that was not resolved by234th there was discernible small scale spatial heterogeneity in mixing as indicated by large variations in bioturbation coefficients estimated in duplicate field or triplicate lab luminophore cores during the sampling period both types of biological sediment transport biodiffusive mixing and bioadvection were low dbranged from 0 001 0 04 cm2day 1andvb 0 00 0 05 cm day 1 biodiffusive mixing estimated fromin situtracer profiles increased lq2 3 during the pulsed organic matter input and temperature rise that characterized the bloom and post bloom period laboratory measurements of luminophores using three replicate cores from each sampling time also indicated a post bloom increase in biodiffusion with a possible transient peak enhancement lw4 about 40 days after the bloom there was an apparent short term relationship between fresh organic flux to the sea floor and elevated biodiffusion but the most consistent post bloom relationship is between mixing rate and temperature apparent activation energies 45 60 kj mol 1 bothin situand laboratory measurements also demonstrated that bioadvection coefficients increased 10 50 with chl ainput and rising temperature and correlated directly with specific changes in benthic community composition diffusive mixing coefficients calculated from the different tracers are of the same order of magnitude use of234th resulted in the lowest estimates of overall particle transport combined diffusive and advective multiple tracers and replication of mixing coefficient measurements are required for accurate quantification and resolution of bioturbation

the 1999 hector mine earthquake southern california vector near field displacements from ers insar two components of fault slip are uniquely determined from two line of sight los radar interferograms by assuming that the fault normal component of displacement is zero we use this approach with ascending and descending interferograms from the ers satellites to estimate surface slip along the hector mine earthquake rupture the los displacement is determined by visually counting fringes to within 1 km of the outboard ruptures these los estimates and uncertainties are then transformed into strike and dip slip estimates and uncertainties the transformation is singular for a n s oriented fault and optimal for an e w oriented fault in contrast to our previous strike slip estimates which were based only on a descending interferogram we now find good agreement with the geological measurements except at the ends of the rupture the ascending interferogram reveals significant west side down dip slip 1 0 m which reduces the strike slip estimates by 1 to 2 m especially along the northern half of the rupture a spike in the strike slip displacement of 6 m is observed in central part of the rupture this large offset is confirmed by subpixel cross correlation of features in the before and after amplitude images in addition to strike slip and dip slip we identify uplift and subsidence along the fault related to the restraining and releasing bends in the fault trace respectively our main conclusion is that at least two look directions are required for accurate estimates of surface slip even along a pure strike slip fault models and results based only on a single look direction could have major errors our new estimates of strike slip and dip slip along the rupture provide a boundary condition for dislocation modeling a simple model which has uniform slip to a depth of 12 km shows good agreement with the observed ascending and descending interferograms

developing sub 5 m lidar dems for forested sections of the alpine and hope faults south island new zealand implications for structural interpretations abstract kilometre wide airborne light detection and ranging lidar surveys were collected along portions of the alpine and hope faults in new zealand to assess the potential for generating sub 5 m bare earth digital elevation models dems from ground return data in areas of dense rainforest bush cover as an aid to mapping these faults the 34 km long franz whataroa lidar survey was flown along the densely vegetated central most portion of the transpressive alpine fault six closely spaced flight lines 200 m apart yielded survey coverage with double overlap of swath collection which was considered necessary due to the low density of ground returns 0 16 m 2 or a point every 6 m2 under mature west coast podocarp broadleaf rainforest this average point spacing 2 5 m allowed for the generation of a robust high quality 3 m bare earth dem the dem confirmed the zigzagged form of the surface trace of the alpine fault in this area originally recognised by norris and cooper 1995 norris and cooper 1997 and highlights that the surface strike variations are more variant than previously mapped the 29 km long hurunui hope lidar survey was flown east of the main divide of the southern alps along the dextral slip hope fault where the terrain is characterised by lower rainfall and more open beech forest flight line spacings of 275 m were used to generate a dem from the ground return data the average ground return values under beech forest were 0 27 m 2 and yielded an estimated cell size suitable for a 2 m dem in both cases the lidar revealed unprecedented views of the surface geomorphology of these active faults lessons learned from our survey methodologies can be employed to plan cost effective high gain airborne surveys to yield bare earth dems underneath vegetated terrain and multi storeyed canopies from densely forested environments across new zealand and worldwide

ground based and uav based photogrammetry a multi scale high resolution mapping tool for structural geology and paleoseismology this contribution reviews the use of modern 3d photo based surface reconstruction techniques for high fidelity surveys of trenches rock exposures and hand specimens to highlight their potential for paleoseismology and structural geology we outline the general approach to data acquisition and processing using ground based photographs acquired from standard dslr cameras and illustrate the use of similar processing approaches on imagery from unmanned aerial vehicles uavs it is shown that digital map and trench data can be acquired at ultra high resolution and in much shorter time intervals than would be normally achievable through conventional grid mapping the resulting point clouds and textured models are inherently multidimensional x y z point orientation colour texture archival and easily transformed into orthorectified photomosaics or digital elevation models dems we provide some examples for the use of such techniques in structural geology and paleoseismology while pointing the interested reader to free and commercial software packages for data processing visualization and 3d interpretation photogrammetric models serve to act as an ideal electronic repository for critical outcrops and observations similar to the electronic lab book approach employed in the biosciences this paper also highlights future possibilities for rapid semi automatic to automatic interpretation of the data and advances in technology

primary surface rupture associated with the mw 7 1 16 october 1999 hector mine earthquake san bernardino county california the m w 7 1 hector mine earthquake occurred within the mojave desert portion of the eastern california shear zone and was accompanied by 48 km of dextral surface rupture complex northward rupture began on two branches of the lavic lake fault in the northern bullion mountains and also propagated southward onto the bullion fault lesser amounts of rupture occurred across two right steps to the south surface rupture was mapped using postearthquake 1 10 000 scale aerial photography field mapping provided additional detail and more than 400 fault rupture observations of these approximately 300 measurements were used to characterize the slip distribution en echelon surface rupture predominated in areas of thick alluvium whereas in the bedrock areas rupture was more continuous and focused within a narrower zone measured dextral offsets were relatively symmetrical about the epicentral region with a maximum displacement of 5 25 0 85 m 1 vertical slip was a secondary component and was variable with minor west side down displacements predominating in the bullion mountains field and aerial photographic evidence indicates that most of the faults that ruptured in 1999 had had prior late quaternary displacement although only limited sections of the rupture show evidence for prior holocene displacement 1 fn 1

is burial velocity a master parameter for bioturbation abstract the intensity of biological mixing in a marine sediment is widely believed to be related to the flux of labile organic matter at the same time this flux has been shown to be strongly correlated to the burial velocity one would then expect a significant correlation between biological mixing coefficient d b and burial velocity a nonlinear regression of existing data with a power law eqns 2 and 3 of the text produces a statistically significant correlation the statistical significance of the regression in no way implies causation and in fact it accounts for only about 22 of the total variance in the dataset thus reducing its physical significance a number of additional processes contribute to the large observed variance including timing of mixing events temporal and spatial heterogeneity differences in temporal scales sampling artifacts and specific particle associations with due care the d b relationship may prove useful in defining the likely range of d b values in a particular environment a similar analysis of the tracer identified surface mixed depth shows that it is essentially independent of burial velocity with a worldwide mean of 9 8 4 5 cm depth of mixing is probably more closely related to the energetic costs of deep burrowing

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

fault kinematics and surface deformation across a releasing bend during the 2010 mw 7 1 darfield new zealand earthquake revealed by differential lidar and cadastral surveying dextral slip at the western end of the east west striking greendale fault during the 2010 m w 7 1 darfield earthquake transferred onto a northwest trending segment across an apparent transtensional zone here named the waterford releasing bend we used detailed surface mapping differential analysis of pre and postearthquake light detection and ranging lidar and property boundary cadastral resurveying to produce high resolution centimeter scale estimates of coseismic ground surface displacements across the waterford releasing bend our results indicate that the change in orientation on the greendale fault incorporates elements of a large scale releasing bend from the viewpoint of westward motion on the south side of the fault as well as a smaller scale restraining stepover from the viewpoint of southeastward motion on the north side of the fault these factors result in the waterford releasing bend exhibiting a decrease in displacement to near zero at the change in strike and the presence within the overall releasing bend of a nested localized restraining stepover with contractional bulging the exceptional detail of surface deformation and kinematics obtained from this contemporary surface rupture event illustrates the value of multimethod investigations our data provide insights into strike slip fault bend kinematics and into the potentially subtle but important structures that may be present at bends on historic and prehistoric rupture traces

bioturbation in the abyssal arabian sea influence of fauna and food supply abstract in order to evaluate bioturbation in abyssal arabian sea sediments of the indus fan profiles of 210 pb half life 22 3 yr and 234 th half life 24 1 d were measured in cores collected during september and october 1995 and april 1997 respectively the density and composition of epibenthic megafauna and lebensspuren were determined in vertical seafloor photographs during april 1997 mean eddy diffusive mixing coefficients according to the distribution of excess 210 pb 210 pb db were 0 072 0 028 0 068 0 055 0 373 0 119 0 037 0 009 and 0 079 0 119 cm2 yr 1 in the northern western central eastern and southern abyssal arabian sea respectively mean eddy diffusive mixing coefficients according to the distribution of excess 234 th 234 th db were 0 53 1 64 and 0 47 cm2 yr 1 in the northern western and central abyssal arabian sea respectively mobile epibenthic megafauna at the western northern central and southern study sites were dominated by ophiuroids holothurians ophiuroids and natant decapods the respective densities were 100 82 29 and 6 individuals 1000 m 2 the northern study site was characterized by a high abundance of spoke traces and fecal casts the central site showed spoke traces and many tracks the southern site displayed the highest abundance of spoke traces whereas at the western site hardly any lebensspuren were observed there is evidence for at least two functional endmember communities in the arabian sea in the northwestern arabian sea wast vertical particle displacement seems to be dominated by macrofauna and primarily eddy diffusive in the southern arabian sea sast non local and incidental mixing due to spoke trace producers might become more important and superimpose reduced eddy diffusive mixing with respect to biological data cast is an intermediate location given the biological data average 210 pb db is higher and decimeter scale variability of 210 pb db smaller at cast than expected these findings indicate that in a mixture of both endmember communities the organisms may interact in way that increases values of biodiffusivity as reflected by 210 pb db and reduces decimeter scale 210 pb db heterogeneity in comparison to the simple sum of the isolated effects of the endmembers for time scales 210 pb db and 234 th db bioturbation intensity should be controlled primarily by the composition of the benthic fauna its specific adaptation to the environmental setting and the abundance of each species of the benthic community food supply can have only an indirect influence on bioturbation intensity in certain parts of the ocean the a priori overall positive relationship between poc flux and biodiffusivity might include restricted intervals displaying no or even negative relations

a generalized stochastic approach to particle dispersal in soils and sediments abstract we explore a generalized stochastic description for the dispersal of particles in soils and sediments the model is based on the continuous time random walk ctrw which enables a very general description of particle mixing due to biological activity a community of burrowing organisms is characterized by a bioturbation fingerprint that consists of two probability distributions the jump length distribution describes the distance a particle travels within a given bioturbation event the waiting time distribution describes the time interval a particle waits at a given location in between two bioturbation events our stochastic analysis provides insight on the applicability of the widely used biodiffusion model which forms the asymptotic limit of the ctrw model this asymptotic behaviour of diffusion is always reached independent of the shape of bioturbation fingerprint provided that the waiting time distribution has a finite mean and the jump length distribution has a finite variance the biodiffusion coefficient can be decomposed as the variance of the jump length distribution over the mean of the waiting time distribution since the variance enables a squared weighing of the jump distance long range displacements will contribute more to the mixing intensity d b than short range displacements therefore large macrofauna will contribute disproportionately to the mixing intensity relative to their abundance as they displace particles over longer distances than smaller organisms finally we review the potential for bioturbation of so called anomalous transport models where either the mean of the waiting time distribution or the variance of the jump length distribution becomes infinite

unconfined aquifer response to infiltration basins and shallow pump tests summary we measure and model the unsteady axisymmetric response of an unconfined aquifer to delayed arbitrary recharge water table drainage follows the initial elastic aquifer response as modeled for uniform instantaneous recharge by zlotnik and ledder zlotnik v ledder g 1992 groundwater flow in a compressible unconfined aquifer with uniform circular recharge water resources research 28 6 1619 1630 and delayed drainage by moench moench a f 1995 combining the neuman and boulton models for flow to a well in an unconfined aquifer ground water 33 3 378 384 we extend their analyses with a convolution integral that models the delayed response of an aquifer to infiltration from a circular infiltration basin the basin routes the hydrograph to the water table with a decay constant dependent on a brooks and corey brooks r h corey a t 1966 properties of porous media affecting fluid flow journal of the irrigation and drainage division asce 92 2 61 88 unsaturated permeability exponent the resulting closed form model approaches neuman s neuman s p 1972 theory of flow in unconfined aquifers considering delayed response of the water table water resources research 8 4 1031 1045 partially penetrating pump test equation for a small source radius instantaneous uniform drainage and a shallow screen section irrigation pump data at a well characterized part of the plymouth carver aquifer in southeastern massachusetts calibrate the small source model while infiltration data from the closed drainage system of state route 25 calibrate the infiltration basin model the calibrated permeability elasticity specific yield and permeability exponent are plausible and consistent for the pump and infiltration data sets

three dimensional surface displacements and rotations from differencing pre and post earthquake lidar point clouds 1 the recent explosion in sub meter resolution airborne lidar data raises the possibility of mapping detailed changes to earth s topography we present a new method that determines three dimensional 3 d coseismic surface displacements and rotations from differencing pre and post earthquake airborne lidar point clouds using the iterative closest point icp algorithm tested on simulated earthquake displacements added to real lidar data along the san andreas fault the method reproduces the input deformation for a grid size of 50 m with horizontal and vertical accuracies of 20 cm and 4 cm values that mimic errors in the original spot height measurements the technique also measures rotations directly resolving the detailed kinematics of distributed zones of faulting where block rotations are common by capturing near fault deformation in 3 d the method offers new constraints on shallow fault slip and rupture zone deformation in turn aiding research into fault zone rheology and long term earthquake repeatability

particle mixing rates in sediments of the northeast tropical atlantic evidence from 210pbxs 137cs 228thxs and 234thxs downcore distributions particle mixing rates were estimated from distribution of 137cs and excess activities of 210pb 228th and 234th measured in nine sediment cores taken from the northeast tropical atlantic i e at the three sites of the french eumeli eutrophic mesotrophic and oligotrophic programme at the oligotrophic site activities of 137cs and excess 210pb decrease smoothly with depth on the other hand at the mesotrophic and eutrophic sites 210pbxs and 137cs profiles suggest a mixing process with three different regimes with subsurface sediments being mixed more rapidly than those at the surface bioturbation rates were found to be slowest at the oligotrophic site intermediate at the mesotrophic site and fastest at the eutrophic site these mixing intensities appear closely linked to benthic fauna abundance organic carbon flux to the sediments and primary production in overlying surface waters the use of a multitracer approach for studying sediment particle reworking has allowed bioturbation rates to be better constrained and an assessment of whether radionuclide distributions in surface sediments are in steady state for only one core from the mesotrophic site were surface sediments not in steady state perhaps because of the occurrence of a benthic animal i e a xenophyophore at the surface of this core

clustering of offsets on the haiyuan fault and their relationship to paleoearthquakes we used airborne light detection and ranging lidar data to reevaluate the single event offsets of the 1920 haiyuan ms 8 5 earthquake and the cumulative offsets along the western and middle segments of the coseismic surface rupture zone our lidar data indicate that the offset observations along both the western and middle segments fall into groups the group with the minimum slip amount is associated with the 1920 haiyuan ms 8 5 earthquake which ruptured both the western and middle segments our research highlights two new interpretations first the previously reported maximum displacement of the 1920 earthquake was likely due to at least two earthquakes second our results reveal that the cumulative offset probability density copd peaks of the same offset amounts on the western and middle segments do not correspond to one another one to one we suggest that any discussion of the rupture pattern of a certain fault based on the offset data should also consider fault segmentation and paleoseismological data therefore the copd peaks should be computed and analyzed on fault subsections and not entire fault zones to study the number of paleoearthquakes and their rupture patterns

time series measurements of macrobenthos abundance and sediment bioturbation intensity on a flood dominated shelf abstract four 70 m stations on the continental shelf offshore from the eel river northern california were occupied at roughly four month intervals between february 1995 and march 1998 and in august 1999 at each of the stations profiles of excess 234 th were used to quantify sediment bioturbation intensity in addition at two of the stations macrofaunal abundance species composition and functional groupings were quantified during the study period the eel river displayed a range of hydrological conditions with historically significant floods in january 1995 and january 1997 return periods of 15 and 40 y respectively relatively low flows during the winters of 1995 1996 and 1998 1999 and an el nino year characterized by moderate but frequent discharges in 1997 1998 the january 1995 and 1997 floods deposited 3 7 cm of fine grained high porosity sediment with high c n ratios and a terrestrial organic carbon signature at the study sites the following general questions are addressed herein 1 how do macrofaunal abundance species composition and functional groupings vary over time 2 does the sediment deposition following the january 1997 flood constitute a major disturbance to the eel shelf macrobenthos 3 how does sediment bioturbation intensity vary in time space and what are the main factors controlling this variation the eel shelf macrofauna is strongly dominated by subsurface deposit feeding polychaetes with anomalously low abundances of surface deposit feeders and virtually no suspension feeders among the community dominants the abundance data revealed a clear seasonal pattern with peak density 4 5 10 4 m 2 in the fall and a factor of two lower density in the late winter spring 2 10 4 m 2 within this seasonal context there was little evidence for extraordinary mortality caused by the january 1997 flood in that overall wintertime mortality and the mortality of most community dominants during a year 1995 1996 when there was no flood deposition were comparable to the mortality observed following the january 1997 flood in contrast the depth distribution of the macrofauna revealed a distinctive post flood pattern whereby a majority 55 70 of individuals were temporarily found at depths 4 cm this pattern suggests an active response by the resident fauna to sediment deposition and supports the idea that the floods did not cause a widespread disturbance although there may not be clear evidence for short term flood effects the overall species composition and functional groupings do imply that the sedimentary environment high sediment accumulation rates and abundant terrestrial organic matter has had a long term influence on the eel shelf macrofauna model fits to 75 profiles of excess 234 th show that in general the data are consistent with a steady state biodiffusive model the resultant mixing intensities ranged from 3 to 325 cm 2 y 1 with averages standard deviation of 35 33 24 19 37 35 and22 9 cm 2 y 1 at stations c70 i70 l70 and o70 respectively the average biodiffusivity for all stations and times was 29 25 cm 2 y 1 n 62 due to the large amount of variability which is consistent with other continental margin studies it was not possible to detect significant spatial or temporal variability although there is a hint of higher mixing intensities during the late summer early fall the period of maximal carbon flux to the seabed correlations between total macrofaunal abundance and mixing intensity are notably poor whereas a slightly better correlation r 2 0 22 was obtained between the abundance of large animals and bioturbation intensity by explicitly considering organic carbon flux or some measure of seabed food resources and the abundance of larger organisms it may be possible to predict bioturbation intensity better in future studies although the pervasive small scale variability detected on the eel river shelf warrants in depth theoretical and experimental consideration

structural analysis of the 1997 mw 7 5 manyi earthquake and the kinematics of the manyi fault central tibetan plateau abstract on 8th november 1997 the mw 7 5 manyi earthquake ruptured the left lateral strike slip manyi fault in the central tibetan plateau despite its large magnitude a comprehensive geological study on the co seismic surface rupture has not yet been reported so far here we reported on our new results of the co seismic surface ruptures and left lateral offsets caused by the earthquake based on detailed interpretation of recently acquired high resolution worldview and spot 5 images we recognized a primary 185 km long surface rupture that trends n80 e in consistence with previous results along the poorly developed segment at the eastern end of the manyi fault a new rupture is also identified which trends n57 e and extends 17 km the co seismic surface rupture zone exhibits many distinct features such as stepovers extensional cracks ponds restraining and releasing bends in relation to fault geometrical complexities by visual analysis of the displaced geomorphic features using satellite imagery we measured 198 co seismic offsets along the 200 km fault trace the results show a 3 7 m average offset and a maximum offset of up to 7 5 m near the epicenter area the newly found 17 km long rupture is interpreted to be linked to the main fault during the event if the manyi fault continues this northeastward propagation for additional 100 km it will separate the bayanhar block into two sub blocks such a new hypothetical block model will influence assessment of seismic potential near the block boundaries and estimate of deformation of the bayanhar block and the central tibetan plateau

high resolution topography derived offsets along the 1857 fort tejon earthquake rupture trace san andreas fault the great fort tejon earthquake of 1857 with an 350 km long surface rupture was the most recent major earthquake along the south central san andreas fault saf prior reconstruction of its surface slip distribution and reconstruction of preceding earthquakes along the 1857 rupture trace have contributed to formulation of the characteristic earthquake cem and uniform slip models usm for earthquake recurrence that find wide application in seismic hazard assessment and earthquake forecasting we used the high resolution b4 light detection and ranging lidar topographic data set sufficient for depiction of meter scale tectonic landforms to reevaluate the distribution of surface displacement along the 1857 rupture trace we present 450 offset measurements with displacements below 60 m increasing observation density relative to previous studies by a factor of 2 our results show that the 1857 earthquake had overall an average displacement below 3 5 m with 4 6 m released along the northwestern half of the rupture its along fault slip distribution is smooth at 10 km length scales at 28 less than prior estimates assuming a 10 km rupture depth and a 30 gpa shear modulus reconstruction of pre 1857 earthquakes is impeded by an exponential decrease in observation density with increasing displacement amount offset observation density soon reaches a level where only tentative and nonunique reconstructions are permitted the results of this study question prior surface slipreconstructions of pre 1857 rupture s that were based on a distinctly lower number of offset observations challenging the applicability of the aforementioned earthquake recurrence models to explain saf rupture behavior online material catalog of offset measurements along the 1857 surface rupture trace as well as an annotated map 1 embed inline graphic 1 gif

particle age distributions and o2 exposure times timescales in bioturbated sediments 1 a stochastic particle tracking approach is used to compute particulate age distributions and oxygen exposure times oets in bioturbated marine sediments simulations representative of abyssal plain continental slope and continental shelf sediments indicate that within the mixed zone the variability in particle age is of the same order of magnitude as the average age itself this spreading of particle age by bioturbation complicates the interpretation of sedimentary archives the results further show that average and median ages of particle bound constituents undergoing decay during early diagenesis deviate from those of inert tracers similarly oets depend on the biological mixing and biogeochemical reactivity of particulate constituents hence ratios of the o2 penetration depth lo2 and the linear sedimentation rate may not offer reliable measures of actual oets taking into account biodiffusional particle mixing and preferential degradation of organic matter under oxygenated conditions the stochastic model predicts a global inverse relationship between the burial efficiency and the oet of organic carbon in ocean sediments the relationship however differs significantly from that proposed by hartnett et al 1998 who used o2 penetration depths divided by linear sedimentation rates lo2 to estimate oets

bias in the paleoceanographic time series tests with a numerical model of u corg and al burial 1 we have constructed a nonsteady state numerical model of organic carbon aluminum and uranium burial to examine the dynamic response of sediments to variations on thousand years scale the three components are defined by distinct behaviors in the sedimentary system the aluminum is a conservative component the organic carbon is a nonconservative component degraded in superficial sediment and the uranium is a component affected by redox conditions by introducing a simultaneous variation of incoming fluxes of corg and al geochemical profiles of al corg and u clearly show separate distributions after burial each component record the synchronous variation of the incoming fluxes but the position in the sedimentary pile of the recording differs from a component to another we show that a minimum of u could be linked to a rapid ascent of the oxic front during an increase in corg flux

estimates of particle flux and reworking at the deep sea floor using234th 238u disequilibrium abstract because of high specific activities of excess234th t1 2 24 1 days on suspended particles in the deep sea this nuclide is potentially an extremely sensitive indicator of particle inputs and dynamics at the seafloor measurements were made at two deep sea sites in order to examine this potential inventories of excess234th at a low current hemipelagic mud site 3990 m in the panama basin were 1 5 september 81 and 2 5 june 82 dpm cm2 the steady state fluxes to the seafloor calculated from these inventories are in rough agreement with radionuclide fluxes measured in sediment traps small scale 100m spatial variability in inventories implies biologically significant heterogeneity in particle inputs sediment from the continental rise site in the northwest atlantic 2800 m a site with higher current velocities than the panama basin had an inventory of 1 9dpm cm2 this inventory is also in rough agreement with predictions made on the basis of nearby sediment trap data particle mixing coefficients of 30cm2 yr calculated at the pacific and atlantic sites are similar to those in shallow water deposits but could reflect disturbance during handling based on210pb data from the panama basin sediment from below 6cm is mixed at a rate 10 slower than the near surface sediment to a depth of at least 20 cm agreement between234th predicted mixing rates at the panama basin site with210pb profiles and in situ experiments with glass bead tracers implies that these rates are real although the diffusion of dissolved234th into deep sea sediments complicates interpretations 234thxs distributions in bottom sediments offer a useful adjunct to sediment traps for investigation of particle dynamics near the deep sea floor

high resolution topography along surface rupture of the 16 october 1999 hector mine california earthquake mw 7 1 from airborne laser swath mapping in order to document surface rupture associated with the hector mine earthquake in particular the area of maximum slip and the deformed surface of lavic lake playa we acquired high resolution data using relatively new topographic mapping methods we performed a raster laser scan of the main surface breaks along the entire rupture zone as well as along an unruptured portion of the bullion fault the image of the ground surface produced by this method is highly detailed comparable to that obtained when geologists make particularly detailed site maps for geomorphic or paleoseismic studies in this case however for the first time after a surface rupturing earthquake the detailed mapping is along the entire fault zone rather than being confined to selected sites these data are geodetically referenced using the global positioning system thus enabling more accurate mapping of the rupture traces in addition digital photographs taken along the same flight lines can be overlaid onto the precise topographic data improving terrain visualization we demonstrate the potential of these techniques for measuring fault slip vectors

laboratory studies of oxic and anoxic degradation of chlorophyll a in long island sound sediments abstract laboratory incubations of long island sound lis sediments show that chlorophyll a chla degradation generally follows first order kinetics but that the rates and mechanisms of degradation differ under oxic and anoxic conditions chl a in fresh sediment can be operationally defined as being present in three pools bound chl a nonextractable by acetone free acetone extractable anoxically degradable chl a and free anoxically stable chl a a major pathway of degradation is initial release of bound chl a into the free pool the release rate constants of bound chl a into free chl a are remarkably faster 10 under oxic 4 d 1 compared to anoxic 0 1 d 1 conditions and a much greater fraction of total chl a degrades under oxic conditions however the apparent degradation rate constants of free chl a are two to three times higher in the absence of oxygen in sediments with high bound chla 0 2 0 3 d 1 for anoxic 0 1 d 1 for oxic and about seven times higher in sediments without bound chl a 0 3 d 1 for anoxic 0 04 d 1 for oxic the differences between anoxic and oxic decomposition in incubation experiments together with naturally observed concentration profiles which reach low levels of chl a imply that chl a in natural sediments degrades during the oscillation between oxic and anoxic conditions caused by physical and biological mixing processes oscillation experiments oxic vs anoxic and anoxic vs oxic suggest that the activities of aerobic organisms may be an important factor affecting chl a degradation examination of effects of meiofauna on chl a degradation under oxic conditions implies that microorganisms may play a stronger role in chl a degradation than meiofauna 0 125 mm the relative temperature independence of anoxic degradation and temperature dependence of oxic degradation suggest that anoxic degradation may be controlled largely by chemical factors while oxic degradation may be more strongly controlled by biophysical and biochemical processes

ensuring confidence in radionuclide based sediment chronologies and bioturbation rates abstract sedimentary records of naturally occurring and fallout derived radionuclides are widely used as tools for estimating both the ages of recent sediments and rates of sedimentation and bioturbation developing these records to the point of data interpretation requires careful sample collection processing analysis and data modeling in this work we document a number of potential pitfalls that can impact sediment core records and their interpretation this paper is not intended as an exhaustive treatment of these potential problems rather the emphasis is on potential problems that are not well documented in the literature as follows 1 the mere sampling of sediment cores at a resolution that is too coarse can result in an apparent diffusive mixing of the sedimentary record at rates comparable to diffusive bioturbation rates observed in many locations 2 210 pb profiles in slowly accumulating sediments can easily be misinterpreted to be driven by sedimentation when in fact bioturbation is the dominant control multiple isotopes of different half lives and or origin may help to distinguish between these two possible interpretations 3 apparent mixing can occur due simply to numerical artifacts inherent in the finite difference approximations of the advection diffusion equation used to model sedimentation and bioturbation model users need to be aware of this potential problem solutions to each of these potential pitfalls are offered to ensure the best possible sediment age estimates and or sedimentation and bioturbation rates can be obtained

what controls the mixed layer depth in deep sea sediments the importance of poc flux the depth of biogenic particle mixing i e the mixed layer depth l is fundamental in models of organic matter recycling and paleoreconstructions for deep sea sediments factors postulated to control l in the oxygenated deep sea include particulate organic carbon poc flux oxygen penetration into the sediment and a balance between the downward mixing and decay of labile poc we explore the dependence of l on biogeochemical characteristics by compiling from 36 sites in three oceans an internally consistent set of deep sea estimates of l poc flux biogenic mixing intensity db and poc reactivity we use excess 210 pb as a tracer for l and db to avoid the confounding effects of tracer dependent mixing we find that l estimated from the penetration depth of excess 210 pb varies systematically with poc flux with an asymptotic function explaining 88 of the variance in l stepwise multiple regression suggests that the penetration depth of excess 210 pb and estimated l is much more likely to be controlled by poc flux than by 1 the sediment inventory of excess 210 pb or 2 biogenic mixing intensity db in addition l is negatively related to oxygen penetration into the sediment r 52 0 629 and not significantly related to predictions of l from a recent mixing poc decay model we conclude that in the food poor deep sea poc flux substantially controls the size and activities of the sediment mixing benthos and in turn the thickness of the biogenic mixed layer thus in contrast to previous suggestions average mixed layer depth is not environmentally invariant but rather responds predictably to ecologically important parameters such as poc flux

geologic and paleoseismic study of the lavic lake fault at lavic lake playa mojave desert southern california paleoseismic investigations of the lavic lake fault at lavic lake playa place constraints on the timing of a possible earlier earthquake along the 1999 hector mine rupture trace and reveal evidence of the timing of the penultimate earthquake on a strand of the lavic lake fault that did not rupture in 1999 three of our four trenches trenches a b and c were excavated across the 1999 hector mine rupture a fourth trench d was excavated across a vegetation lineament that had only minor slip at its southern end in 1999 trenches a c exposed strata that are broken only by the 1999 rupture trench d exposed horizontal bedding that is locally warped and offset by faults stratigraphic evidence for the timing of an earlier earthquake along the 1999 rupture across lavic lake playa was not exposed thus an earlier event if there was one along that rupture trace predates the lowest stratigraphic level exposed in our trenches radiocarbon dating of strata near the bottom of trenches constrains a possible earlier event to some time earlier than about 4950 b c buried faults revealed in trench d are below a vegetation lineament at the ground surface a depositional contact about 80 cm below the ground surface acts as the upward termination of fault breaks in trench d thus this contact may be the event horizon for a surface rupturing earthquake prior to 1999 the penultimate earthquake on the lavic lake fault radiocarbon ages of detrital charcoal samples from immediately below the event horizon indicate that the earthquake associated with the faulting occurred later than a d 260 an approximately 1300 year age difference between two samples at about the same stratigraphic level below the event horizon suggests the potential for a long residence time of detrital charcoal in the area coupled with a lack of bioturbation that could introduce young organic material into the stratigraphic section the charcoal ages provide only a maximum bounding age thus the recognized event may be younger there is abundant subtle evidence for pre 1999 activity of the lavic lake fault in the playa area even though the fault was not mapped near the playa prior to the hector mine earthquake the most notable indicators for long term presence of the fault are pronounced persistent vegetation lineaments and uplifted basalt exposures primary and secondary slip occurred in 1999 on two southern vegetation lineaments and minor slip locally formed on a northern lineament trench exposures across the northern vegetation lineament revealed the post a d 260 earthquake and a geomorphic trough extends northward into alluvial fan deposits in line with this lineament the presence of two basalt exposures in lavic lake playa indicates the presence of persistent compressional steps and uplift along the fault fault line scarps are additional geomorphic markers of repeated slip events in basalt exposures

active tectonics in 4d high resolution abstract with a little more than 100 years since the publication of seminal and field defining investigations active tectonics is still a relatively young sub discipline of structural geology this research field addresses the accumulation of strain due to plate tectonic motion and more importantly release thereof through the occurrence of earthquakes or other strain releasing events in that regard active tectonics aims to characterize the incremental steps of plate tectonics determining earthquake chronologies fault slip rates and other common objectives importantly feed into our understanding of for example fault mechanics and crustal rheology characterizing the recurrence of large and potentially devastating earthquakes is further motivated by seismic hazard assessment and risk mitigation the primary data source in active tectonics is surface and shallow subsurface evidence of faulting presenting itself in topographic and stratigraphic data sets respectively field observations and air photo interpretation of displaced stratigraphic and geomorphic markers were used almost 40 years ago to formulate end member models of earthquake recurrence technological developments since then especially within the last two decades have dramatically increased the abundance and resolution of topographic data sets and the ability to date stratigraphic units and geomorphic surfaces enabling the formulation of better informed conceptual models of earthquake recurrence here we provide an overview of the high resolution topographic data sets and dating methods that enabled the recent advances of active tectonics

airborne laser altimeter survey of long valley california summary airborne laser altimetry has proved useful in recent years in examining volcanic landforms and glacial ice sheets with the advent of accurate differential gps aircraft tracking we believe that airborne lasers will also prove useful in monitoring timevarying topographic uplift with rates as low as several centimetres of vertical motion per year the long valley california caldera provides an excellent testing ground for this new technology the region has a history of extensive volcanism and its central dome has recently been undergoing resurgent uplift of up to 4 cm per year in september 1993 we conducted three aircraft topographic surveys over the caldera and resurgent dome utilizing a nasa t39 jet aircraft outfitted with a nadir profiling altimetric laser atlas two p code gps receivers a litton ltn92 inertial unit for attitude and aerial cameras in addition we operated two base station gps receivers for post flight differential navigation and conducted a kinematic automobile survey of roads crossing the dome the aircraft flew at a mean altitude of 500m above ground and at speeds of 80 100 m s the laser had a divergence of 1 7 mrad and output 50 pulses per second yielding footprints of 0 9 m diameter separated by about 2 m along track precision flying yielded multiple profiles along nearly identical paths including crossing profiles over the resurgent dome off the dome and along a nearby highway the surveys included daily flights over mono lake for roll and pitch bias calibrations and over the well surveyed lake crowley to provide an independent check of estimated elevations much progress has been made in developing analysis procedures for the laser timing and attitude corrections crossover points from repeated profiles over the dome and the lake indicate that although some profiles contain relative bias errors of up to 10 cm most are substantially more accurate the accuracy of the measurements will increase as the various sources of error are better defined and dealt with even with the present analysis level the distribution of crossovers near the centre of the dome is roughly gaussian with a mean of 2 6 cm and a standard deviation of 11 cm the standard error of the mean is low 1 cm due to the high number of crossover points which holds promise for measuring systematic changes in the dome height from year to year also comparison of laser heights of lake crowley to tidal gauge heights yields only a 1 4 cm difference in absolute height these encouraging results serve to confirm further the concept of using aircraft laser surveys for geodetic tectonic monitoring

fault slip distribution of the 1999 mw 7 1 hector mine earthquake california estimated from postearthquake airborne lidar data the 16 october 1999 hector mine earthquake m w 7 1 was the first large earthquake for which postearthquake airborne light detection and ranging lidar data were collected to image the fault surface rupture in this work we present measurements of both vertical and horizontal slip along the entire surface rupture of this earthquake based on airborne lidar data acquired in april 2000 we examine the details of the along fault slip distribution of this earthquake based on 255 horizontal and 85 vertical displacements using a 0 5 m digital elevation model derived from the lidar imagery the slip measurements based on the lidar dataset are highest in the epicentral region and taper in both directions consistent with earlier findings by other works the maximum dextral displacement measured from lidar imagery is 6 60 1 10 m located about 700 m south of the highest field measurement 5 25 0 85 m our results also illustrate the difficulty in resolving displacements smaller than 1 m using lidar imagery alone we analyze slip variation to see if it is affected by rock type and whether variations are statistically significant this study demonstrates that a postearthquake airborne lidar survey can produce an along fault horizontal and vertical offset distribution plot of a quality comparable to a reconnaissance field survey although lidar data can provide a higher sampling density and enable rapid data analysis for documenting slip distributions we find that relative to field methods it has a limited ability to resolve slip that is distributed over several fault strands across a zone we recommend a combined approach that merges field observation with lidar analysis so that the best attributes of both quantitative topographic and geological insight are utilized in concert to make best estimates of offsets and their uncertainties

particle mixing rates in deep sea sediments determined from excess 210pb and 32si profiles particle mixing rates have been determined for 5 south atlantic antarctic and 3 equatorial pacific deep sea cores using excess 210 pb and 32 si measurements radionuclide profiles from these siliceous calcareous and clay rich sediments have been evaluated using a steady state vertical advection diffusion model in antarctic siliceous sediments 210 pb mixing coefficients 0 04 0 16 cm 2 y are in reasonable agreement with the 32 si mixing coefficient 0 2 or 0 4 cm 2 y depending on 32 si half life in an equatorial pacific sediment core however the 210 pb mixing coefficient 0 22 cm 2 y is 3 7 times greater than the 32 si mixing coefficient 0 03 or 0 07 cm 2 y the difference in 210 pb and 32 si mixing rates in the pacific sediments results from 1 non steady state mixing and differences in characteristic time and depth scales of the two radionuclides 2 preferential mixing of fine grained clay particles containing most of the 210 pb activity relative to coarser particles large radiolaria containing the 32 si activity or 3 the supply of 222 rn from the bottom of manganese nodules which increases the measured excess 210 pb activity relative to 226 ra at depth and artificially increases the 210 pb mixing coefficient based on 32 si data and pore water silica profiles dissolution of biogenic silica in the sediment column appears to have a minor effect on the 32 si profile in the mixed layer deep sea particle mixing rates reported in this study and the literature do not correlate with sediment type sediment accumulation rate or surface productivity based on differences in mixing rate among three antarctic cores collected within 50 km of each other local variability in the intensity of deep sea mixing appears to be as important as regional differences in sediment properties

continuous gps observations of postseismic deformation following the 16 october 1999 hector mine california earthquake mw 7 1 rapid field deployment of a new type of continuously operating global positioning system gps network and data from southern california integrated gps network scign stations that had recently begun operating in the area allow unique observations of the postseismic deformation associated with the 1999 hector mine earthquake innovative solutions in fieldcraft devised for the 11 new gps stations provide high quality observations with 1 year time histories on stable monuments at remote sites we report on our results from processing the postseismic gps data available from these sites as well as 8 other scign stations within 80 km of the event a total of 19 sites from these data we analyze the temporal character and spatial pattern of the postseismic transients data from some sites display statistically significant time variation in their velocities although this is less certain the spatial pattern of change in the postseismic velocity field also appears to have changed the pattern now is similar to the pre landers pre 1992 secular field but laterally shifted and locally at twice the rate we speculate that a 30 km 50 km portion of crust near twentynine palms which was moving at nearly the north american plate rate to within 3 5 mm yr of that rate prior to the 1992 landers sequence now is moving along with the crust to the west of it as though it has been entrained in flow along with the pacific plate as a result of the landers and hector mine earthquake sequence the inboard axis of right lateral shear deformation at lower crustal to upper mantle depth may have jumped 30 km farther into the continental crust at this fault junction that comprises the southern end of the eastern california shear zone

airborne lidar analysis and geochronology of faulted glacial moraines in the tahoe sierra frontal fault zone reveal substantial seismic hazards in the lake tahoe region california nevada usa we integrated high resolution bare earth airborne light detection and ranging lidar imagery with field observations and modern geochronology to characterize the tahoe sierra frontal fault zone which forms the neotectonic boundary between the sierra nevada and the basin and range province west of lake tahoe the lidar imagery clearly delineates active normal faults that have displaced late pleistocene glacial moraines and holocene alluvium along 30 km of linear right stepping range front of the tahoe sierra frontal fault zone herein we illustrate and describe the tectonic geomorphology of faulted lateral moraines we have developed new three dimensional modeling techniques that utilize the high resolution lidar data to determine tectonic displacements of moraine crests and alluvium the statistically robust displacement models combined with new ages of the displaced tioga 20 8 1 4 ka and tahoe 69 2 4 8 ka 73 2 8 7 ka moraines are used to estimate the minimum vertical separation rate at 17 sites along the tahoe sierra frontal fault zone near the northern end of the study area the minimum vertical separation rate is 1 5 0 4 mm yr which represents a two to threefold increase in estimates of seismic moment for the lake tahoe basin from this study we conclude that potential earthquake moment magnitudes m w range from 6 3 0 25 to 6 9 0 25 a close spatial association of landslides and active faults suggests that landslides have been seismically triggered our study underscores that the tahoe sierra frontal fault zone poses substantial seismic and landslide hazards

surface slip gradients of large earthquakes for earthquakes that are large enough to break the earth s surface slip can be measured directly providing model independent information of spatially vary ing behavior in earthquakes here new techniques are developed and applied to extract robust measures of surface slip in particular i examine how differences in slip scale with differences in separation examining slip distributions of seven large earthquakes in a digital database i find that the curves collapse into a common behavior over kilometer to tens of kilometer length scales distributions of differences of slip are found to be reasonably well fit by normal distributions with the variance of the dis tributions scaling with separation distance in particular average slip differences are seen to be increasing linearly out to length scales of the seismogenic crust but with a nonzero intercept when extrapolated back to a zero separation of around 1 m offset the variability of slip extrapolated to zero separation the mean offset of around 1 m 96 15 m is a remarkable feature of the observations holding for all seven of the large earthquakes analyzed leaving aside the offset and looking at the increase as a function of separation the slope or lateral strain has a value consistent with large scale average strains thus behavior consistent with constant stress drop is seen at length scales smaller than the event size revealing a further invariant of earthquake dy namics finally taking into account the noisy environment by looking for coherent structures unlikely to be noise related i find structures which have moderate values of lateral strains on the order of a factor of 10 times mean values with values appearing to be independent of length scale and magnitude

late pleistocene slip rate of the central haiyuan fault constrained from optically stimulated luminescence 14c and cosmogenic isotope dating and high resolution topography the haiyuan fault is a major left lateral active fault of the india asia collision zone while the 1000 km long fault between hala lake in the west to liupan shan in the east accommodates eastward displacement of northeast tibet relative to the gobi alashan to the north the amount of slip accumulated and its slip rate remain debated we revisit the site of daqing or sangedun at 102 7 e in gaudemer et al 1995 to better constrain the long term slip rate of the haiyuan fault in its central part we used terrestrial lidar to build a high resolution dem and unmanned aerial vehicle to build an aerial photomosaic with 0 1 m resolution to survey the offset terraces their geomorphology and the fault trace we refine the geomorphological interpretation of the site measure riser offsets and determine their relation to terrace formation the well constrained age of the highest terrace t3 at 13 7 1 5 ka determined from the combination of surface and sub surface osl 14 c and terrestrial in situ 10 be cosmogenic nuclide dating associated with the maximum lower terrace riser offset of 88 m yield a minimum slip rate of 6 4 1 2 mm yr over the late pleistocene the age of the intermediate terrace t2 is bracketed between 8 0 ka 14 c and 12 ka 10 be the ages and vertical offsets of the 2 highest terraces is used to infer the age of t2 offset vertically 5 7 m at 5 4 1 ka its 29 2 m offset is consistent with a rate of 6 5 mm yr given the vertical offset youngest terrace t1 of 1 3 0 2 m its age is estimated at 1 2 0 2 ka in agreement with the youngest surface exposure age overall a slip rate of 5 8 mm yr fits all offset and age data at the daqing site the smallest offset of a gully incised into t1 of 6 0 0 5 m is potentially associated with the most recent slip event that occurred in the last millennia

steady state tracer dynamics in a lattice automaton model of bioturbation the intensity of biogenic sediment mixing is often expressed as a biodiffusion coefficient db quantified by fitting a diffusive model of bioturbation to vertical profiles of particle bound radioisotopes the biodiffusion coefficient often exhibits a dependence on tracer half life short lived radioisotopes e g 234th tend to yield notably larger db values than longer lived radioisotopes e g 210pb it has been hypothesized that this is a result of differential mixing of tracers by particle selective benthos this study employs a lattice automaton model of bioturbation to explore how steady state tracers with different half lives are mixed in typical marine settings every particle in the model is tagged with the same array of radioisotopes so that all tracers experienced exactly the same degree of mixing two different estimates of the mixing intensity are calculated a tracer derived db obtained in the standard way by fitting the biodiffusion model to resulting tracer profiles and a particle tracking db derived from the statistics of particle movements the latter provides a tracer independent measure of mixing for use as a reference our simulations demonstrate that an apparent db tracer dependence results from violating the underlying assumptions of the biodiffusion model breakdown of the model is rarely apparent from tracer profiles emphasizing the need to evaluate the model s criteria from biological and ecological parameters rather than relying on obvious indications of model breakdown e g subsurface maxima simulations of various marine environments coastal slope abyssal suggest that the time scales of short lived radioisotopes such as 234th and 7be are insufficient for the tracers to be used with the biodiffusion model 210pb appears an appropriate tracer for abyssal sediments while 210pb and 228th are suitable for slope and coastal sediments

bioturbation and erosion rates along the soil hillslope conveyor belt part 2 quantification using an analytical solution of the diffusion advection equation particles on soil mantled hillslopes are subject to downslope transport by erosion processes and vertical mixing by bioturbation both are key processes for understanding landscape evolution and soil formation and affect the functioning of the critical zone we show here how the depth age information derived from feldspar based single grain post infrared infrared stimulated luminescence pirir can be used to simultaneously quantify erosion and bioturbation processes along a hillslope in this study we propose for the first time an analytical solution for the diffusion advection equation to calculate the diffusivity constant and erosion deposition rates we have fitted this model to age depth data derived from 15 soil samples from four soil profiles along a catena located under natural grassland in the santa clotilde critical zone observatory in the south of spain a global sensitivity analysis was used to assess the relative importance of each model parameter in the output finally the posterior probability density functions were calculated to evaluate the uncertainty in the model parameter estimates the results show that the diffusivity constant at the surface varies from 11 4 to 81 9 mm2 a 1 for the hilltop and hill base profile respectively and between 7 4 and 64 8 mm2 a 1 at 50 cm depth the uncertainty in the estimation of the erosion deposition rates was found to be too high to make a reliable estimate probably because erosion deposition processes are much slower than bioturbation processes in this environment this is confirmed by a global sensitivity analysis that shows how the most important parameters controlling the age depth structure in this environment are the diffusivity constant and regolith depth finally we have found a good agreement between the soil reworking rates proposed by earlier studies considering only particle age and depth and the estimated diffusivity constants the soil reworking rates are effective rates corrected for the proportion of particles actually participating in the process

optimization of legacy lidar data sets for measuring near field earthquake displacements airborne lidar light detection and ranging topography acquired before and after an earthquake can provide an estimate of the coseismic surface displacement field by differencing the preevent and postevent lidar point clouds however estimated displacements can be contaminated by the presence of large systematic errors in either of the point clouds we present three dimensional displacements obtained by differencing airborne lidar point clouds collected before and after the el mayor cucapah earthquake a mw 7 2 earthquake that occurred in 2010 the original surface displacement estimates contained large periodic artifacts caused by systematic errors in the preevent lidar data reprocessing the preevent data detailed herein removed a majority of these systematic errors that were largely due to misalignment between the scanning mirror and the outgoing laser beam the methodology presented can be applied to other legacy airborne laser scanning data sets in order to improve change estimates from temporally spaced lidar acquisitions

a reductionist physical approach to unsaturated aquifer recharge from a circular spreading basin in this paper the process of aquifer recharge from a circular area through the unsaturated zone is investigated the same basic methodology described previously by the authors for the case of a long strip recharging area morel seytoux et al 1988 is applied an approximate solution to the three dimensional problem is obtained by matching two unidimensional flows a vertical and a radial one the mathematical formulation is obtained first for the case of a constant infiltration rate and then for a time dependent rate through the unsaturated zone the formulation leads to an integrodifferential equation whose solution is obtained numerically using the discrete kernel approach morel seytoux et al 1973 morel seytoux and daly 1975 in both cases concrete examples illustrate the influence of the parameters on the discharge into the saturated zone and on the water table level also a criterion to evaluate the efficiency of the recharge is provided for practical purposes this criterion allows comparison between different recharge designs

coseismic deformation from the 1999 mw 7 1 hector mine california earthquake as inferred from insar and gps observations we use interferometric synthetic aperture radar insar and global positioning system gps observations to investigate static deformation due to the 1999 m w 7 1 hector mine earthquake that occurred in the eastern california shear zone interferometric decorrelation phase and azimuth offset measurements indicate regions of surface and near surface slip which we use to constrain the geometry of surface rupture the inferred geometry is spatially complex with multiple strands the southern third of the rupture zone consists of three subparallel segments extending about 20 km in length in a n45 w direction the central segment is the simplest with a single strand crossing the bullion mountains and a strike of n10 w the northern third of the rupture zone is characterized by multiple splays with directions subparallel to strikes in the southern and central the average strike for the entire rupture is about n30 w the interferograms indicate significant along strike variations in strain which are consistent with variations in the ground based slip measurements using a variable resolution data sampling routine to reduce the computational burden we invert the insar and gps data for the fault geometry and distribution of slip we compare results from assuming an elastic half space and a layered elastic space results from these two elastic models are similar although the layered space model predicts more slip at depth than does the half space model the layered model predicts a maximum coseismic slip of more than 5 m at a depth of 3 to 6 km contrary to preliminary reports the northern part of the hector mine rupture accommodates the maximum slip our model predictions for the surface fault offset and total seismic moment agree with both field mapping results and recent seismic models the inferred shallow slip deficit is enigmatic and may suggest that distributed inelastic yielding occurred in the uppermost few kilometers of the crust during or soon after the earthquake

accuracy and resolution of shuttle radar topography mission data 1 we assess the accuracy and resolution of topography data provided by the shuttle radar topography mission srtm through spectral comparisons with the national elevation dataset ned and a high resolution laser data set of the 1999 hector mine earthquake rupture we find that srtm and the ned are coherent for wavelengths greater than 200 m however the spatial resolution of the ned data is superior to the srtm data for wavelengths shorter than 350 m likely due to the application of a boxcar filter applied during final srtm processing stages from these results a low pass filter decimation algorithm can be designed in order to expedite large area srtm applications

the 2010 2011 canterbury earthquake sequence environmental effects seismic triggering thresholds and geologic legacy abstract seismic shaking and tectonic deformation during strong earthquakes can trigger widespread environmental effects the severity and extent of a given effect relates to the characteristics of the causative earthquake and the intrinsic properties of the affected media documentation of earthquake environmental effects in well instrumented historical earthquakes can enable seismologic triggering thresholds to be estimated across a spectrum of geologic topographic and hydrologic site conditions and implemented into seismic hazard assessments geotechnical engineering designs palaeoseismic interpretations and forecasts of the impacts of future earthquakes the 2010 2011 canterbury earthquake sequence ces including the moment magnitude m w 7 1 darfield earthquake and m w 6 2 6 0 5 9 and 5 8 aftershocks occurred on a suite of previously unidentified primarily blind active faults in the eastern south island of new zealand the ces is one of earth s best recorded historical earthquake sequences the location of the ces proximal to and beneath a major urban centre enabled rapid and detailed collection of vast amounts of field geospatial geotechnical hydrologic biologic and seismologic data and allowed incremental and cumulative environmental responses to seismic forcing to be documented throughout a protracted earthquake sequence the ces caused multiple instances of tectonic surface deformation 3 events surface manifestations of liquefaction 11 events lateral spreading 6 events rockfall 6 events cliff collapse 3 events subsidence 4 events and hydrological 10s of events and biological shifts 3 events the terrestrial area affected by strong shaking e g peak ground acceleration pga 0 1 0 3 g and the maximum distances between earthquake rupture and environmental response r rup both generally increased with increased earthquake m w but were also influenced by earthquake location and source characteristics however the severity of a given environmental response at any given site related predominantly to ground shaking characteristics pga peak ground velocities and site conditions water table depth soil type geomorphic and topographic setting rather than earthquake m w in most cases the most severe liquefaction rockfall cliff collapse subsidence flooding tree damage and biologic habitat changes were triggered by proximal moderate magnitude m w 6 2 earthquakes on blind faults ces environmental effects will be incompletely preserved in the geologic record and variably diagnostic of spatial and temporal earthquake clustering liquefaction feeder dikes in areas of severe and recurrent liquefaction will provide the best preserved and potentially most diagnostic ces features rockfall talus deposits and boulders will be well preserved and potentially diagnostic of the strong intensity of ces shaking but challenging to decipher in terms of single versus multiple events most other phenomena will be transient e g distal groundwater responses not uniquely diagnostic of earthquakes e g flooding or more ambiguous e g biologic changes preliminary palaeoseismic investigations in the ces region indicate recurrence of liquefaction in susceptible sediments of 100 to 300 yr recurrence of severe rockfall event s of ca 6000 to 8000 yr and recurrence of surface rupturing on the largest ces source fault of ca 20 000 to 30 000 yr these data highlight the importance of utilising multiple proxy datasets in palaeoearthquake studies the severity of environmental effects triggered during the strongest ces earthquakes was as great as or equivalent to any historic or prehistoric effects recorded in the geologic record we suggest that the shaking caused by rupture of local blind faults in the ces comprised a worst case seismic shaking scenario for parts of the christchurch urban area moderate m w blind fault earthquakes may contribute the highest proportion of seismic hazard be the most important drivers of landscape evolution and dominate the palaeoseismic record in some locations on earth including locations distal from any identified active faults a high scientific priority should be placed on improving the spatial extent and quality of off fault shaking records of strong earthquakes particularly near major urban centres