conditional probabilities for large events estimated by small earthquake rate we examined forecasting quiescence and activation models to obtain the conditional probability that a large earthquake will occur in a specific time period on different scales in taiwan the basic idea of the quiescence and activation models is to use earthquakes that have magnitudes larger than the completeness magnitude to compute the expected properties of large earthquakes we calculated the probability time series for the whole taiwan region and for three subareas of taiwan the western eastern and northeastern taiwan regions using 40 years of data from the central weather bureau catalog in the probability time series for the eastern and northeastern taiwan regions a high probability value is usually yielded in cluster events such as events with foreshocks and events that all occur in a short time period in addition to the time series we produced probability maps by calculating the conditional probability for every grid point at the time just before a large earthquake the probability maps show that high probability values are yielded around the epicenter before a large earthquake the receiver operating characteristic roc curves of the probability maps demonstrate that the probability maps are not random forecasts but also suggest that lowering the magnitude of a forecasted large earthquake may not improve the forecast method itself from both the probability time series and probability maps it can be observed that the probability obtained from the quiescence model increases before a large earthquake and the probability obtained from the activation model increases as the large earthquakes occur the results lead us to conclude that the quiescence model has better forecast potential than the activation model

seismic evidence for an earthquake nucleation phase near source observations show that earthquakes initiate with a distinctive seismic nucleation phase that is characterized by a low rate of moment release relative to the rest of the event this phase was observed for the 30 earthquakes having moment magnitudes 2 6 to 8 1 and the size and duration of this phase scale with the eventual size of the earthquake during the nucleation phase moment release was irregular and appears to have been confined to a limited region of the fault it was characteristically followed by quadratic growth in the moment rate as rupture began to propagate away from the nucleation zone these observations suggest that the nucleation process exerts a strong influence on the size of the eventual earthquake

towards a formal description of foraminiferal assemblage formation in shallow water environments qualitative and quantitative concepts the use of foraminifera in palaeoenvironmental reconstructions e g sea level may be complicated by processes such as infaunal test production taphonomic degradation and bioturbation which act to modify contemporary analogue surface assemblages during and subsequent to burial understanding the palaeoenvironmental significance of these processes is limited by the absence of a clear theoretical description of the mechanics of foraminiferal assemblage formation a conceptual framework is proposed which describes assemblage formation in terms of the balance of test inputs and losses within a volume of sediment undergoing burial through the upper sedimentary zones of test production taphonomic processes and bioturbation a corresponding mathematical model is described and shown to explain empirical dead test distributions in terms of empirically defined standing crops sedimentation and mixing rates together with model estimates of standing crop turnover and or taphonomic decay rates this approach provides a quantitative basis for understanding assemblage formation and for comparing assemblage forming processes between species environments and study sites rates of standing crop turnover and taphonomic loss are identified as the primary unknowns in the study of foraminiferal assemblage formation these multiple unknowns make interpretations of cored data ambiguous emphasising the need for a detailed and coherent framework of theory and assumptions for understanding the mechanics assemblage formation if interpretations are to be clear and conclusive

major storm periods and climate forcing in the western mediterranean during the late holocene abstract big storm events represent a major risk for populations and infrastructures settled on coastal lowlands in the western mediterranean where human societies colonized and occupied the coastal areas since the ancient times the variability of storm activity for the past three millennia was investigated with a multi proxy sedimentological and geochemical study from a lagoonal sequence mappings of the geochemistry and magnetic susceptibility of detrital sources in the watershed of the lagoon and from the coastal barriers were undertaken in order to track the terrestrial or coastal marine origin of sediments deposited into the lagoon the multi proxy analysis shows that coarser material low magnetic susceptibility and high strontium content characterize the sedimentological signature of the paleostorm levels identified in the lagoonal sequence a comparison with north atlantic and western mediterranean paleoclimate proxies shows that the phases of high storm activity occurred during cold periods suggesting a climatically controlled mechanism for the occurrence of these storm periods besides an in phase storm activity pattern is found between the western mediterranean and northern europe spectral analyses performed on the sr content revealed a new 270 year solar driven pattern of storm cyclicity for the last 3000 years this 270 year cycle defines a succession of ten major storm periods sp with a mean duration of 96 54 yr periods of higher storm activity are recorded from 680 to 560 cal yr bc sp10 end of the iron age cold period from 140 to 820 cal yr ad sp7 to sp5 with a climax of storminess between 400 and 800 cal yr ad dark ages cold period and from 1230 to 1800 cal yr ad sp3 to sp1 little ice age periods of low storm activity occurred from 560 cal yr bc to 140 cal yr ad sp9 and sp8 roman warm period and from 820 to 1230 cal yr ad sp4 medieval warm period

intense southwest florida hurricane landfalls over the past 1000 years abstract recent research has proposed that human induced sea surface temperature sst warming has led to an increase in the intensity of hurricanes over the past 30 years however this notion has been challenged on the basis that the instrumental record is too short and unreliable to reveal long term trends in hurricane activity this study addresses this limitation by investigating hurricane induced overwash deposits paleotempestites behind a barrier island in naples fl usa paleotempestologic proxies including grain size percent calcium carbonate and fossil shells species were used to distinguish overwash events in two sediment cores spanning the last one thousand years two prominent paleotempestites were observed in the top 20 cm of both cores the first identified as hurricane donna in 1960 whereas an older paleotempestite 1900 1930 could represent one of three documented storms in the early 1900s an active period of hurricane overwash from 1000 to 500 yrs bp and an inactive period from 500 to 150 yrs bp correlate with reconstructed ssts from the main development region mdr of the north atlantic ocean we observe an increased number of paleotempestites when mdr ssts are warmer coinciding with the medieval warm period and very few paleotempestites when mdr ssts are cooler coinciding with the little ice age results from this initial southwest florida study indicate that mdr ssts have been a key long term climate driver of intense southwest florida hurricane strikes

correlations in aftershock and seismicity patterns correlations in space and time play a fundamental role in earthquake processes one direct manifestation of the effects of correlations is the occurrence of aftershocks due to the stress transfer in the vicinity of a main shock less obvious and more speculative changes in correlations may occur in the background seismicity before large earthquakes using statistical physics it is possible to introduce a measure of spatial correlations through a correlation length this quantity characterizes how local fluctuations can influence the occurrence of earthquakes over distances comparable with the correlation length in this work the physical basis of spatial correlations of earthquakes is discussed in the context of critical phenomena and the percolation problem the method of two point correlation function is applied to the seismicity of california well defined variations in time of the correlation length are found for aftershock sequences and background seismicity the scaling properties of our obtained distributions are analyzed with respect to changes in several scaling parameters such as lower magnitude cutoff of earthquakes the maximum time interval between earthquakes and the spatial size of the area considered this scaling behavior can be described in a unified manner by utilizing the multifractal fit utilizing the percolation approach the time evolution of clusters of earthquakes is studied with the correlation length defined in terms of the radius of gyration of clusters this method is applied to the seismicity of california

the statistical mechanics of earthquakes abstract we review recent theoretical developments on the physics of earthquakes in particular we focus on the rise of the statistical mechanical view of earthquakes as a kind of phase transition this view is appealing in light of the well known scaling relations such as the gutenberg richter magnitude frequency and omori s law of aftershock decay scaling relations such as these which are in reality power laws are known to be associated with dynamical systems residing near a critical point in the state space of the system these second order critical points are associated with second order transitions which are a result of gradual changes of the controlling parameters at the same time characteristic earthquakes which involve the entire fault segment sliding nearly at once are more reminiscent of a first order transition which is characterized by sudden widespread changes in the physical state of the system in this paper we review these ideas and show how recent developments are leading to a view of earthquake fault systems based on modern statistical mechanics

earthquake precursors activation or quiescence summary we discuss the long standing question of whether the probability for large earthquake occurrence magnitudes m 6 0 is highest during time periods of smaller event activation or highest during time periods of smaller event quiescence the physics of the activation model are based on an idea from the theory of nucleation that a small magnitude earthquake has a finite probability of growing into a large earthquake the physics of the quiescence model is based on the idea that the occurrence of smaller earthquakes here considered as magnitudes m 3 5 may be due to a mechanism such as critical slowing down in which fluctuations in systems with long range interactions tend to be suppressed prior to large nucleation events to illuminate this question we construct two end member forecast models illustrating respectively activation and quiescence the activation model assumes only that activation can occur either via aftershock nucleation or triggering but expresses no choice as to which mechanism is preferred both of these models are in fact a means of filtering the seismicity time series to compute probabilities using 25 yr of data from the california nevada catalogue of earthquakes we show that of the two models activation and quiescence the latter appears to be the better model as judged by backtesting by a slight but not significant margin we then examine simulation data from a topologically realistic earthquake model for california seismicity virtual california this model includes not only earthquakes produced from increases in stress on the fault system but also background and off fault seismicity produced by a bass etas driving mechanism applying the activation and quiescence forecast models to the simulated data we come to the opposite conclusion here the activation forecast model is preferred to the quiescence model presumably due to the fact that the bass component of the model is essentially a model for activated seismicity these results lead to the weak conclusion that california seismicity may be characterized more by quiescence than by activation and that bass etas models may not be robustly applicable to the real data

paleotempestology database for the western north atlantic basin paleotempestology the study of past tropical cyclone activity has grown considerably over the past two decades and there is now a relatively dense network of sites across the western north atlan

evidence for possible precursor events of megathrust earthquakes on the west coast of north america megathrust earthquakes in western north america may be preceded by a precursor phase several years prior to megathrust induced earthquakes for example on 27 march 1964 a 9 2 magnitude on the richter scale earthquake occurred on the coast of alaska changes in foraminifera and diatom assemblages at girdwood flats alaska provide evidence of a precursor to this earthquake thereby detailing a previously unknown sequence of events we describe further evidence of precursor phases from marshes in turnagain arm alaska united states and farther south in netarts bay oregon united states this is the first time that two widely spaced locations have been examined for earthquake related precursor stages the alaska earthquake offers the possibility to compare a modern sequence a d 1964 of events with the geologic record the netarts bay marsh has experienced no modern earthquake that could be used for comparison but the nature of megathrust zones implies that the modern and ancient events should be physically similar new cores examined from turnagain arm include both the 1964 earthquake and an event identified and dated at 1800 yr b p prior to the 1964 event the foraminifera and thecamoebian assemblages changed from a forest phase to a mildly brackish stage this sequence was dated as being 15 yr or less in length using pb210 and cs137 dating techniques the event at 1800 yr b p was also associated with a similar precursor stage indicating a small subsidence prior to the megathrust earthquake related subsidence event in netarts bay a new core was taken at a previously cored site to make use of carbon 14 dates and the assurance that at least four events were known to have occurred over the past 3000 yr the new core contains four transitions each identified by a mineralic deposit often sharply bounded below and gradationally overlain by marsh peat transition in this context refers to the section of core analyzed 15 cm above and below each of the four sand layers foraminiferal assemblage analyses indicate that these units represented a high marsh prequake phase followed by a lower marsh precursor stage the earthquake related deposition sand layer and then a rebound back into postquake marsh deposits sand deposits with either no or few foraminifera are inferred as tsunami earthquake related deposition stages these transitions in two widely separated geographic areas alaska and oregon indicate that similar mechanisms operate for large megathrust earthquakes at subduction zones from alaska to northern california in the cascadia subduction zone thus implying that precursor events also occur and can be detected by foraminiferal zonation all along this area in a recent article dragert et al 2001 1 scientists from the west coast suggested that slow or silent earthquakes they measured with continuous geographical positioning systems might be indicators of megathrust earthquakes the transitions we document may be the prehistoric representations of these silent quakes foraminiferal evidence may help by allowing more accurate positioning of seismometers along the west coast of north america and thereby lead to more precise and timely earthquake prediction methods 1 ref 14

assessing surficial foraminiferal distributions as an overwash indicator in sur lagoon sultanate of oman abstract the identification of tsunami and storm deposits in arid coastal environments can be problematic as overwash sediments may not show significant contrasting lithologic characters with lagoonal sediments in this study foraminifera were evaluated as an overwash indicator in a small 12 km2 intertidal lagoon located at sur in the sultanate of oman the lagoon is shallow

tropical cyclone activity and western north atlantic stratification over the last millennium a comparative review with viable connections tropical cyclones tc are recognized to modify the thermal structure of the upper ocean through the process of vertical mixing assessing the role this mixing plays in the overall stratification of the upper ocean is difficult due to the relatively short and incomplete instrumental record proxy records for both tc landfalls and oceanographic stratification are preserved within the geological record and provide insight for how past changes in tc induced mixing have potentially affected water column structure prior to the instrumental record here we provide the first comparison between previously published paleo reconstructions of vertical ocean density and tropical cyclone activity from the western north atlantic a prominent lull in tc activity has been observed prior to approximately 1700 ce that extends back several centuries this interval of low tc activity is shown to be concurrent with the timing of increased ocean stratification near great bahama bank potentially due in part to reduced tc induced mixing to test whether this relationship is feasible we present numerical results from a coarse resolution ocean general circulation model experiment isolating the effect of tc surface wind forcing on the upper ocean an anomaly of roughly 0 12 kg m 3 in vertical stratification occurs above and below the mixed layer for model runs with and without tc mixing this anomaly is roughly 25 of the entire paleo density signal observed just prior to 1700 ce these results suggest that tc mixing alone cannot completely explain the density anomaly observed prior to 1700 ce but support tc variability as an important contributor to enhancing oceanic stratification during this interval copyright 2011 john wiley sons ltd

constitutive relations between dynamic physical parameters near a tip of the propagating slip zone during stick slip shear failure abstract constitutive relations between physical parameters in the cohesive zone during stick slip shear failure are experimentally investigated stick slip was generated along a 40 cm long precut fault in tsukuba granite samples using a servocontrolled biaxial loading apparatus dynamic behavior during local breakdown processes near a tip of the slipping zone is revealed the slip velocity and acceleration are given as a function of the slip displacement and the cohesive or breakdown shear stress as a function of the slip velocity a cycle of the breakdown and restrengthening process of stick slip is composed of five phases characterized in terms of the cohesive strength and the slip velocity the cohesive strength can degrade regardless of the slip velocity during slip instabilities the maximum slip acceleration u max and the maximum slip velocity u max are obtained experimentally as u max 2 u c u max 2 and u max b g v where u c is the critical displacement b the breakdown stress drop g the rigidity and v the rupture velocity these relations are consistent with ida s theoretical estimation based on the cohesive zone model the above formula gives good estimates for the maximum slip acceleration of actual earthquakes the cutoff frequency max of the power spectral density of the slip acceleration increases with increasing normal stress in particular max is found to be directly proportional to the normal stress n within the normal stress range less than 17 mpa as max khz 4 0 n mpa n max increase with an increase in u max or u max all these results lead to the conclusion that u max u max and max increase with increasing normal stress this is consistent with a previous observation that b increases with increasing normal stress the above empirical linear relation between max and n can be explained by a linear dependence of b on n the size scale dependence of physical parameters is discussed and such size scale dependent parameters as u max and apparent fracture energy are scaled to the breakdown zone size regarded as a characteristic length to extend the results obtained in the laboratory to an earthquake failure in the earth

the spatial and vertical distribution of living stained benthic foraminifera from a tropical intertidal environment north queensland australia we investigated the distribution of living stained benthic foraminifera across a tropical intertidal shoreline adjacent to cocoa creek queensland australia for the purpose of better understanding the nature of test production and ultimately fossil assemblage development within such environments short cores up to 1 m were collected during the wet and dry season along an elevational gradient comprising non vegetated intertidal mudflat and higher intertidal mangrove forest environments the distribution of stained specimens can be broadly delineated into assemblages characterising upper mangrove 2 64 2 91 m above lowest astronomical tide lat and low mangrove mudflat 1 62 2 18 m above lat environments agglutinated species were generally limited to upper mangrove stations calcareous species occurred within all of the intertidal environments examined but differ in their composition between upper and lower intertidal settings upper mangrove faunas were characterised by the agglutinated species arenoparrella mexicana haplophragmoides wilberti miliammina fusca miliammina obliqua and trochammina inflata and the calcareous species helenina anderseni live stained assemblages at lower intertidal elevations were dominated by the calcareous species ammonia aoteana as well as rosalina spp elphidium oceanicum triloculina oblonga ammonia pustulosa and shackoinella globosa absolute densities of stained specimens were lowest within the low mangrove sediments 6 8 specimens per cm2 but higher within the upper mangrove 25 249 specimens per cm2 and mudflat 8 77 specimens per cm2 abundances within mudflat sediments varied seasonally being significantly larger in the wet season whereas those within mangrove zone sediments changed little through the year stained foraminifera were found to a maximum depth of 50 cm at cocoa creek extending to the greatest depth at the upper mangrove stations and were generally shallowest beneath the lower mangroves all stations had over 50 of their foraminiferal standing crop below the upper 1 cm although at most stations 10 of living specimens occurred within this layer comparison of this data with dead assemblages suggests that 1 abundances of stained specimens averaged over two sampling events reasonably approximate aggregate in situ test production and 2 a clear enrichment of infaunal species occurs within the mangrove the latter effect was less conspicuous on the mudflat due to high rates of mixing and assemblage time averaging which obscure the signal of test production within the dead assemblages in both cases the validity and stratigraphic resolution of surface assemblages for sea level and other palaeoenvironmental reconstructions is questionable

abrupt deep sea warming palaeoceanographic changes and benthic extinctions at the end of the palaeocene a remarkable oxygen and carbon isotope excursion occurred in antarctic waters near the end of the palaeocene 57 33 myr ago indicating rapid global warming and oceanographic changes that caused one of the largest deep sea benthic extinctions of the past 90 million years in contrast the oceanic plankton were largely unaffected implying a decoupling of the deep and shallow ecosystems the data suggest that for a few thousand years ocean circulation underwent fundamental changes producing a transient state that although brief had long term effects on environmental and biotic evolution

temporal assessment of sediment transport from beach nourishments by using foraminifera as natural tracers this paper presents the application of a technique that can be easily applied in monitoring programs following beach fills where sand is dredged from subtidal zones seabed or bays usually rich in foraminifera shells its utility lies in a simple and rapid estimation of the prevailing longshore transport paths and determination of the main eroding accreting zones a beach monitoring program was undertaken in a embayment on the south atlantic spanish coast where several nourishments were carried out in order to recover an eroding beach once the nourishment was complete a temporal analysis of foraminifera shell distribution was made in a nearby beach inside the embayment by monthly sediment sampling foraminifera shells were used as natural tracers for estimating sediment pathways the results showed a complex pattern of sedimentary transport between both beaches where wind action and reflected diffracted waves interfered with the dominant longshore current depending on the prevailing hydrodynamic regime these results were later confirmed by a 3 year morphodynamic study although foraminifera dispersion only accounts for the behaviour of fine fractions the monitoring of shell dispersion after dumping demonstrated to be a useful tool for studying the stability of nourished beaches in the case of nourished beaches foraminifera shells could be considered as mixed tracers with many advantages over both natural and artificial traditional tracers

incorporating temporal and spatial variability of salt marsh foraminifera into sea level reconstructions abstract foraminifera from salt marsh environments have been used extensively in quantitative relative sea level reconstructions due to their strong relationship with tidal level however the influence of temporal and spatial variability of salt marsh foraminifera on quantitative reconstructions remains unconstrained here we conducted a monitoring study of foraminifera from four intertidal monitoring stations in new jersey from high marsh environments over three years that included several extreme weather temperature precipitation and storm surge events we sampled four replicates from each station seasonally four times per year for a total of 188 samples the dead foraminiferal assemblages were separated into four site specific assemblages after accounting for systematic trends in changes in foraminifera over time among stations the distribution of foraminiferal assemblages across monitoring stations explained 87 of the remaining variation while 13 can be explained by temporal and or spatial variability among the replicate samples we applied a bayesian transfer function to estimate the elevation of the four monitoring stations all samples from each station predicted an elevation estimate within a 95 uncertainty interval consistent with the observed elevation of that station combining samples into replicate and seasonal aggregate datasets decreased elevation estimate uncertainty with the greatest decrease in aggregate datasets from fall and winter information about the temporal and spatial variability of modern foraminiferal distributions was formally incorporated into the bayesian transfer function through informative foraminifera variability priors and was applied to a common era relative sea level record in new jersey the average difference in paleomarsh elevation estimates and uncertainties using an informative vs uninformative prior was minimal

phytolith assemblages as indicators of coastal environmental changes and hurricane overwash deposition we demonstrate that phytolith assemblages are a useful proxy for reconstructing coastal environmental changes and for validating the overwash origin of sand layers in palaeotempestology studies phytolith analysis was conducted on 50 topsoil or surface sediment samples collected from a variety of coastal plant communities or depositional environments in the southeastern usa the data suggest that different coastal subenvironments can be distinguished by their modern phytolith assemblages for example coastal marsh samples contain a diverse phytolith assemblage dominated by smooth elongate and square morpho types and maritime forest samples are dominated by phytoliths from palms and broadleaf dicotyledonous plants remarkably the phytolith assemblages from sand dunes are characterized by high percentages of two horned tower flat tower spool horned tower and short saddle types phytolith analysis of three prehistoric sand layers in a sediment core from western lake northwestern florida shows that they contain a phytolith assemblage similar to those characteristic of sand dunes and interdune meadows these observations are confirmed by the results of principal components analysis and discriminant analysis on the modern and fossil phytolith data sets our study results support the interpretation that the sand layers in western lake were indeed formed by the erosion of sand dunes during overwash processes caused by landfalling catastrophic hurricanes

a 1900 year paleohurricane record from wassaw island georgia usa we present here the first paleotempestology record from wassaw island on the georgia bight located in the south atlantic coast of the united states in the historical period the georgia bight has experienced less frequent hits by hurricanes than other locations along the us gulf and atlantic coasts the 1900 year record inferred from the overwash sand layers from a back barrier marsh on wassaw island suggests that the island was directly struck by major storms on nine occasions during this interval the wassaw island record shows alternating regimes with periods of increased activity from 2000 a bp until 1100 a bp and 100 a bp until the present sandwiching a quiet period from 1100 to 250 a bp storm deposits from the most recent active period are perhaps amalgamated indicating that site specific conditions may result in event undercounting and suggests that the relative thickness of sand layers in the sedimentary record is not always indicative of hurricane strength copyright 2011 john wiley sons ltd

instability model for recurring large and great earthquakes in southern california the locked section of the san andreas fault in southern california has experienced a number of large and great earthquakes in the past and thus is expected to have more in the future to estimate the location time and slip of the next few earthquakes an earthquake instability model is formulated the model is similar to one recently developed for moderate earthquakes on the san andreas fault near parkfield california in both models unstable faulting the earthquake analog is caused by failure of all or part of a patch of brittle strain softening fault zone in the present model the patch extends downward from the ground surface to about 12 km depth and extends 500 km along strike from parkfield to the salton sea the variation of patch strength along strike is adjusted by trial until the computed sequence of instabilities matches the sequence of large and great earthquakes sincea d 1080 reported by sieh and others the last earthquake was them 8 3 ft tejon event in 1857 the resulting strength variation has five contiguous sections of alternately low and high strength from north to south the approximate locations of the sections are 1 parkfield to bitterwater valley 2 bitterwater valley to lake hughes 3 lake hughes to san bernardino 4 san bernardino to palm springs and 5 palm springs to the salton sea sections 1 3 and 5 have strengths between 53 and 88 bars sections 2 and 4 have strengths between 164 and 193 bars patch section ends and unstable rupture ends usually coincide although one or more adjacent patch sections may fail unstably at once the model predicts that the next sections of the fault to slip unstably will be 1 3 and 5 the order and dates depend on the assumed length of an earthquake rupture in about 1700

microhabitats of salt marsh foraminifera st catherines island georgia usa abstract salt marsh foraminifera of st catherines island georgia occupy a range of epibenthic to deep infaunal to 30 cm micro habitats freshly collected specimens of arenoparrella mexicana from 27 to 30 cm below the marsh surface extruded pseudopodial nets and actively collected foreign material about the aperture salt marsh foraminifera may be primarily epibenthic 0 1 cm epibenthic to intermediate infaunal 0 10 cm or deep infaunal 0 30 cm most of the twelve commonly occurring species in st catherines island marshes are epibenthic to intermediate infaunal species distributional patterns differ with regard to maximum depth of infaunal occurrences infaunal microhabitat utilization in different marsh zones and environments and the presence or absence of subsurface population maxima selective preservation impacts both calcareous and agglutinated foraminifera intense bioturbation primarily by halophytes and decapod crustaceans may contribute to the deep infaunal occurrences of foraminifera in these environments

micropaleontology of the 2013 typhoon haiyan overwash sediments from the leyte gulf philippines abstract coastal geologic records allow for the assessment of long term patterns of tropical cyclone variability however the accuracy of geologic reconstructions of tropical cyclones is limited by the lack of modern analogues we describe the microfossil foraminifera and testate amoebae assemblages contained within overwash sediments deposited by typhoon haiyan when it made landfall on the islands of leyte and samar in the philippines on 7 november 2013 as a category 5 super typhoon the overwash sediments were transported up to 1 7 km inland at four study sites the sediments consisted of light brown medium sand in a layer

mixing sedimentation rates and age dating for sediment cores abstract analytic solutions to the advection diffusion equation useful as a guide for the interpretation of mixing sedimentation rate and age dating effects in sediment cores have been derived various simplified mixing models appropriate to 14 c and 210 pb measurements have been considered the emphasis has been on a discussion of the various interrelations and dependencies among the mixing coefficient sedimentation rate and radioactive decay constant parameters in determining the 14 c and 210 pb concentrations as a function of depth porosity variations within the sediment column are also considered and the transformed advection diffusion equation including porosity effects is derived

forecast model for large and great earthquakes in southern california an earthquake instability model is used to compute theoretical fault slip and ground surface deformation before possible future earthquakes on the san andreas fault in southern california the quasistatic model represents the earth s crust by an elastic half space and the san andreas imperial cerro prieto and san jacinto faults by flat rectangular surfaces whose strikes approximate the actual local strikes the seismogenic zone of the san andreas fault is represented by a brittle strain softening patch extending from the ground surface to 11 km depth and from parkfield to the salton sea 500 km the strength of the patch varies along strike and unstable failures of parts of the patch are earthquake analogs failed areas heal immediately after instability for the model to reproduce the lengths slips and times of earthquakes since 1080 a d reported by k sieh and others the patch must be divided into five sections along strike the sections have alternately low and high strength with the two strongest sections being roughly coincident with the major bends of the san andreas fault ten to twenty years before unstable slippage of patch areas portions of the patch bottom begin to fail stably aseismically the stable failure causes accelerating fault slip at depth and at the fault trace as well as anomalous changes in lengthening rates of trilateration lines in the model simulation the next two sections to fail unstably in the future are just north of the salton sea and just south of parkfield rupture lengths are about 100 km and 40 km at favorable locations precursory anomalies of fault slip and trilateration line length become large enough to be detected in field data a few years before each earthquake

uranium thorium and lead nuclides in a delaware salt marsh sediment natural isotopes of uranium 234 238 thorium 232 230 and lead 210 have been assayed in sediments from a lower delaware salt marsh uranium is concentrated in the top sections of the core and decreases with depth 3 to 1 d min 1 g 1 a significant proportion of this uranium has been authigenically extracted from seawater as demonstrated by an excess ratio of 234u 238u 1 03 1 14 thorium 232 is rather constant 2 4 4 7 parts 10 6 for all but one sample while the concentration of 230th is deficient with respect to its uranium parent in contrast to the deep sea the fixation of authigenic reduced uranium dominates over the scavenging of 230th in these tidal sediments excess 210pb shows an exponential decay over the length of the core and when corrected for a correspondingly significant exponential decrease in organic carbon and salt yields a sedimentation rate of 0 47 cm year 1 although this rate approximates the local apparent rate of sea level rise a lower limit for the rate of salt marsh accumulation the actual rate is higher suggesting net filling and acccretion of salt marshes the total integrated flux of 210pb to this and other salt marsh surfaces in the eastern u s is calculated to more often exceed the reported local atmospheric flux it appears that salt marshes may scavenge 210pb as other trace metals from flooding waters

spatio lateral continuity of hurricane deposits in back barrier marshes sedimentological and micropaleontological analysis of fifteen 3 m gouge auger cores revealed a lack of spatio lateral continuity for paleohurricane deposits from the back barrier marshes of folly island south carolina the offshore indicative calcareous microfossil content of some storm deposits was taphonomically altered or destroyed and in many cases cores taken 10 m apart provided significantly different storm records in several low marsh cores where bioturbation is more intense storm deposits were completely unrecognizable using foraminifer or sedimentological analyses in nearly all cores the sedimentary record of storm deposits was more extensive than the record produced using foraminifers and as a result the sedimentary proxy produced shorter hurricane return periods while offshore indicative foraminifers in the salt marshes behind folly island are good indicators of their original source and mode of deposition storm current transport from the shelf by overwash storm inlet or via lighthouse inlet their susceptibility to destruction from bioturbation and dissolution suggests that they provide a less accurate or less complete record of storm frequency than previously thought

historical nankai suruga megathrust earthquakes recorded by tsunami and terrestrial mass movement deposits on the shirasuka coastal lowlands shizuoka prefecture japan geological investigations of coastal sediment sequences play a key role in verifying earthquake and tsunami characteristics inferred from historical records in this paper we present a multi proxy investigation of a coastal lowland site facing the nankai suruga megathrust and appraise evidence for tsunamis and earthquake triggered terrestrial mass movements occurring over the last 800 years combining a high resolution chronology with x ray computed tomography and analyses of particle size diatoms pollen non pollen palynomorphs and aerial photographs we present the most compelling geological evidence of the 1361 ce koan also known as shohei tsunami reported to date from any site along the megathrust this finding is consistent with either of two recent hypotheses a single larger rupture of both the nankai and tnankai regions or two smaller ruptures separated by a few days enhancing the site chronology using bayesian age modelling we verify evidence for inundation during the 1498 ce mei tsunami while previous investigations identified evidence for historically recorded tsunamis in 1605 1707 and 1854 ce and a storm surge in 1680 or 1699 ce we encountered a thick sand layer rather than discrete extreme wave deposits in this interval the overprinting of evidence highlights the potential for geological records to underestimate the frequency of these events a terrestrial mass movement also deposited a sand layer at the site radionuclide dating and aerial photographs provide independent confirmation that this may have been triggered by intense shaking in 1944 ce during the most recent great nankai suruga megathrust earthquake

hurricane signatures and landforms toward improved interpretations and global storm climate chronology abstract the correct understanding of the geological and geomorphic evolution of paralic basins and coastal barriers is a prerequisite for establishing holocene hurricane archives worldwide detection and documentation of hurricane signatures in coastal deposits are becoming instrumental in attempts to reconstruct mid and late holocene storm climate history subsurface exploration and field studies on the ne gulf coast and data gleaned from the literature suggest the need for a complex approach that provides well documented details of coastal landscape evolution until recently prehistoric hurricanes and their intensity levels have been automatically interpreted from the frequency and thickness of sand layers in muddy paralic deposits however in addition to wind velocity several hydro aerodynamic and other factors a wide range of stratigraphic conditions topographic setting and sand sources also determine variations in the extent and intensity of storm flooding erosion transfer and deposition of sand layers in small paralic basins inherent limitations in these sedimentary records and their interpretation must be overcome in order to improve local hurricane chronologies and establish interregional correlations before sedimentary and chemical signatures are accepted as diagnostic indicators of overwash especially by catastrophic hurricanes alternative causes must also be considered a parallel scale of storm flood level stages should supplement the saffir simpson hurricane categories the relationship between storm intensities and flooding elevations is highly complex changes in sea level shore positions formation and extinction of preexisting incised valley networks the impact of transgression and regression processes on estuaries and their deposits play determining roles in setting the stage for overwash processes strandplain progradation followed by erosive shore retreat played a key role in framing certain paralic lakes without overwash sand layers and marine microfossils may be also emplaced by storm driven currents that enter unobstructed estuaries inlets and storm breaches bioturbation also distorts the storm record significant lateral variations in the number and thickness of intercalated sand layers at closely adjacent sites suggest the importance of local differences in sources transport and preservation processes in the dimensions relative positions and accessibility of sand resources inside and adjacent to coastal basins variations in the number thickness and ages of sand laminae may not be related to the number of storms and their intensities this may impair correlations between regionally interpreted calm and intensive phases in partial overlap with an assumed quiescent storm phase stable isotope ratios in lacustrine muds impacted by salt water influx reveal frequent hurricane activity during the last 1 5 ka as well by mimicking effects of reduced storminess the fewer and thinner sand laminae deposited between 7 0 and 3 4 ka b p may be attributed to greater distances of estuarine landward transport by storm tidal currents at times of lower sea levels

premonitory spreading of seismicity over the faults network in southern california precursor accord 1 we establish a connection between geometry of the faults network in a region and seismicity preceding the strong earthquakes in the intermediate term timescale of years previous studies of observed and computer simulated seismicity demonstrated that strong earthquakes are preceded in that timescale by the rise of seismic activity in a lower magnitude range here we explore a complementary phenomenon spreading of activity over the fault network this phenomenon is depicted by the seismicity pattern accord defined as a simultaneous rise of seismicity in a sufficiently large number of fault zones hence its name pattern accord has been found recently in synthetic seismicity generated by the colliding cascades cc model the present study demonstrates this pattern in observed seismicity of southern california we applied to observations a prediction algorithm based on the pattern accord scaled to the target magnitude 7 5 the pattern accord emerges within a few years before each of the three largest earthquakes in southern california kern county 1952 landers 1992 and hector mine 1999 and at no other time scaled to the target magnitude interval from 6 5 to 7 4 the pattern accord precedes six out of nine earthquakes the duration of alarms in both cases is about 30 of the time considered we repeated prediction with different combinations of adjustable numerical parameters of the algorithm summing up the success and error scores on an error diagram this numerical experiment shows that the prediction results are stable under moderate variations of adjustable parameters the final test would be as always an advance prediction the pattern accord has a simple physical explanation connected with equilibrium of the crustal blocks system under the impact of tectonic driving forces at the same time accord is a manifestation of a broader phenomenon premonitory increase of earthquakes correlation range the latter phenomenon was found for the first time in the cc model although it was hypothesized by one of the authors much earlier

foraminifera reveal a shallow nearshore origin for overwash sediments deposited by tropical cyclone pam in vanuatu south pacific abstract tropical cyclone inundation is a major threat to the highly exposed islands of the south pacific this vulnerability was highlighted in march 2015 when tropical cyclone tc pam made landfall on vanuatu as a category 5 storm impacting coastlines with storm surges that produced high water marks up to 7 m above mean sea level msl and deposited overwash sediments up to 400 m inland we examined the foraminiferal assemblages contained within tc pam sediments at two locations in vanuatu a mixed carbonate embayment at manuro on efate island and a volcaniclastic beach at port resolution bay on tanna island at manuro the tc pam sediments were up to 10 cm thick and composed of coarse to medium sand that contained abundant foraminifera 955 to 2015 individuals per 5 cm3 and fragments of corals and mollusks at port resolution bay tc pam sediments were up to 44 cm thick and composed of medium sand sized volcaniclastics with low to moderate abundances of foraminifera 27 to 206 individuals per 5 cm3 tc pam sediments could be discriminated from underlying units by a sharp basal contact an abrupt decrease in organic matter and an increase in the concentration of foraminifera foraminiferal assemblages between the two sites varied in terms of taxonomy and taphonomy at both sites the tc pam assemblage was generally dominated by intertidal e g amphistegina spp baculogypsina sphaerulata calcarina mayori elphidium spp pararotalia spp and subtidal e g peneroplis pertusus quinqueloculina spp foraminifera that are characteristic of beach reef flat and reef crest environments the tc pam assemblage at manuro was characterized by individuals that were dominantly unaltered i e pristine but also those that showed signs of abrasion including edge rounded fragments by contrast tc pam sediments at port resolution bay contained fewer unaltered and more corraded i e combined influence of corrosion and abrasion foraminifera we compared modern surface foraminiferal distributions with those from tc pam sediments to assess provenance partitioning around a medoid pam cluster analysis discriminated six subenvironments within the modern coastal zone open bay forereef reef crest reef flat mangrove and beach discrete intervals sampled from tc pam sediments at manuro were individually clustered with the surface samples and revealed a shallow nearshore to supratidal reef crest to beach 4 9 to 1 3 m above msl source for the sand

the sedimentary record of the 2005 hurricane season from the mississippi and alabama coastlines abstract the instrumental record of hurricane activity is too short to fully capture the occurrence of the rare but most destructive hurricanes therefore obtaining a record of present and past landfalling hurricanes and their extent of geological and ecological impacts is one means to assess future risk reveal the spatial and temporal variability of hurricane activity and decipher its relationship with global climatic changes we rapidly dispatched survey teams to collect the readily available but perishable data of hurricanes katrina and rita storm surge from two salt marshes in mississippi and one salt marsh in alabama in mississippi we recorded hurricane katrina storm surge heights greater than 7 5 m north american vertical datum 88 navd88 with inland extents in excess of 700 m whereas in alabama the maximum recorded storm surge was 3 43 m navd88 at one salt marsh in mississippi we recorded the maximum inland extent and elevation of maximum penetration of hurricane rita as 370 m and 3 43 m navd88 respectively we observed a three dimensional distribution of hurricane induced storm surge deposits that tapered landward overlying salt marsh sediment there was a sharp or erosional boundary between the pre storm surge and storm surge sedimentary units which was accompanied by a change in color and lithology the overlying storm surge sediment unit was coarser than the pre storm surge unit with a lower organic content the thickness of the hurricanes katrina and rita storm surge sediments ranged from 9 to 13 cm and approximately 7 cm respectively foraminiferal analyses revealed a virtual absence of tests within the storm surge sediments whereas abundant agglutinated foraminifera were found in the underlying salt marsh deposits

pattern dynamics and forecast methods in seismically active regions large extended fault systems such as those in california demonstrate complex space time seismicity patterns which include repetitive events precursory activity and quiescence and aftershock sequences although the characteristics of these patterns can be qualitatively described a systematic quantitative analysis remains elusive our research suggests that a new pattern dynamics methodology can be used to define a unique finite set of seismicity patterns for a given fault system in addition while a long sought goal of earthquake research has been the reliable forecasting of these events very little progress has been made in developing a successful consistent methodology in this report we document the discovery of systematic space time variations in seismicity from southern california using a new technique here we present examples of this analysis technique on data obtained prior to events in seismically active areas that show coherent regions associated with the future occurrence of major earthquakes in the same areas these results strongly support the hypothesis that seismic activity is highly correlated across many space and time scales within large volumes of the earth s crust

foraminifera as an indicator of overwash deposits barrier island sediment supply and barrier island evolution folly island south carolina abstract micropaleontological analysis of four vibracores from back barrier marshes of folly island south carolina detected intervals of storm deposited sediment individual washover intervals were not detectable from lithology alone but only in conjunction with associated foraminifera washovers contained more modern offshore and oligo miocene genera and total calcareous foraminifera than background marsh samples the presence of tertiary foraminifera in the back barrier cores from folly island supports the hypothesis that much of the sediment for barrier island migration is derived from offshore foraminiferal analyses of back barrier cores were also used to calculate relative bioturbation rates by the method of officer and lynch officer c b lynch d r 1983 mixing sedimentation rates and age dating for sediment cores mar geol 46 261 278 eqs 10 14 in all cores the current depositional environment correlated well with the expected mixing parameter g the highest mixing parameter greatest signal attenuation was recorded in a core from a low marsh creek side environment whereas the lowest mixing parameter least smearing of signal was recorded in a high marsh core

palaeohurricane reconstructions from sedimentary archives along the gulf of mexico caribbean sea and western north atlantic ocean margins hurricanes annually threaten the atlantic ocean margins historical hurricane records are relatively short and palaeohurricane sedimentary archives provide a geological and climatic context that sheds light on future hurricane activity here we review palaeo trends in hurricane activity elucidated from sedimentary archives we discuss dating methods site selection and stat istics associated with previously published records these archives have been useful for under standing the long term evolution of coastal systems and the response of intense hurricane activity to climatic changes regional shifts in hurricane overwash on centennial to millennial timescales have been linked to various climatic modes of variability including el nino southern oscillation and the north atlantic oscillation but could also reflect regional scale controls on hurricane activity

the application of δ13c toc and c n geochemistry of mangrove sediments to reconstruct holocene paleoenvironments and relative sea levels puerto rico abstract we assessed the use of 13c toc and c n values of bulk sedimentary organic matter om to reconstruct paleoenvironmental and relative sea level change from mangrove environments in puerto rico the modern distribution of 13c toc and c n values was described from 63 vegetation and 59 surface sediment samples collected from three sites containing basin and riverine mangrove stands and was compared to microfossil foraminiferal and thecamoebian assemblages four vertically zoned environments were identified tidal flat 13c 18 6 2 8 toc 10 2 5 7 c n 12 7 3 1 mangrove 13c 26 4 1 0 toc 33 9 13 4 c n 24 3 6 2 brackish transition 13c 28 8 0 7 toc 40 8 11 7 c n 21 7 3 7 and freshwater swamp 13c 28 4 0 4 toc 42 8 4 8 c n 17 0 1 1 these environments had distinct 13c toc and c n values with the exception of the brackish transition and freshwater swamp zones that were difficult to distinguish on a geochemical basis alone the foraminiferal assemblages were complicated by a group that did not show a relationship to elevation due to the presence of calcareous foraminifera occurring above mean higher high water mhhw likely resulting from washover or transport by storms however the ratio of foraminifera to thecamoebians f t along with 13c toc and c n values refines the distinction between brackish and freshwater environments using linear discriminant analysis we applied the 13c toc c n and f t distributions to a 1 7 m core containing a continuous sequence of rhizophora mangle peat which began accumulating at 1650 1930 ce together microfossils 13c toc and c n values and the core chronology from 137cs and radiocarbon dating revealed that sediments in the core likely accumulated in response to anthropogenic sediment delivery making it unsuitable for relative sea level reconstruction we caution that in the absence of detailed litho bio chemo or chrono stratigraphic analyses as presented here care should be taken in interpreting sea level histories derived from single dates on mangrove peats

evidence for and implications of self healing pulses of slip in earthquake rupture dislocation time histories of models derived from waveforms of seven earthquakes are discussed in each model dislocation rise times the duration of slip for a given point on the fault are found to be short compared to the overall duration of the earthquake 10 however in many crack like numerical models of dynamic rupture the slip duration at a given point is comparable to the overall duration of the rupture i e slip at a given point continues until information is received that the rupture has stopped propagating alternative explanations for the discrepancy between the short slip durations used to model waveforms and the long slip durations inferred from dynamic crack models are 1 the dislocation models are unable to resolve the relatively slow parts of earthquake slip and have seriously underestimated the dislocations for these earthquakes 2 earthquakes are composed of a sequence of small dimension short duration events that are separated by locked regions barriers 3 rupture occurs in a narrow self healing pulse of slip that travels along the fault surface evidence is discussed that suggests that slip durations are indeed short and that the self healing slip pulse model is the most appropriate explanation a qualitative model is presented that produces self healing slip pulses the key feature of the model is the assumption that friction on the fault surface is inversely related to the local slip velocity the model has the following features high static strength of materials kilobar range low static stress drops in the range of tens of bars and relatively low frictional stress during slip less than several hundreds of bars it is suggested that the reason that the average dislocation scales with fault length is because large amplitude slip pulses are difficult to stop and hence tend to propagate large distances this model may explain why seismicity and ambient stress are low along fault segments that have experienced large earthquakes it also qualitatively explains why the recurrence time for large earthquakes may be irregular

implications of a statistical physics approach for earthquake hazard assessment and forecasting there is accumulating evidence that distributed seismicity is a problem in statistical physics seismicity is taken to be a type example of self organized criticality this association has important implications regarding earthquake hazard assessment and forecasting a characteristic of a thermodynamic system is that it exhibits a background noise that is self organized in the case of a dilute gas this self organization is the maxwell boltzmann distribution of molecular velocities in seismicity it is the gutenberg richter frequency magnitude scaling this scaling is fractal observations favor the hypothesis that smaller earthquakes in moderate sized regions occur at rates that are only weakly dependent on time thus the rate of occurrence of smaller earthquakes can be extrapolated to assess the hazard of larger earthquakes in a region we obtain the rate of occurrence of earthquakes with m 4 in 1 1 areas from the neic catalog using only this data we produce global maps of the seismic hazard observations also favor the hypothesis that the stress level at which an earthquake occurs is a second order critical point as a critical point is approached correlations extend over increasingly larger distances in terms of seismicity the approach to a critical point is associated with an increase in the rate of occurrence of intermediate sized earthquakes prior to a large earthquake this precursory activation has been shown to exhibit power law scaling and to occur over a region about ten times larger than the rupture length of the large earthquake analyses of the spinoidal behavior associated with second order critical points predict the power law increase in seismic activity prior to a characteristic earthquake this precursory activation provides the basis for intermediate range earthquake forecasting

records of prehistoric hurricanes on the south carolina coast based on micropaleontological and sedimentological evidence with comparison to other atlantic coast records singleton swash on the south carolina coast provides an extended record of storm events for this coast we used experience gained by looking at storm traces detected as layers of offshore foraminifera intercalated with marsh sediments from a known storm in the area hugo which occurred in 1989 to detect storm horizons from the sediments that have been accumulating in singleton swash since 5700 yr b p we suggest here that the most intense storm activity occurred in the 0 1000 yr b p interval six storms only three occurred in the 1000 2000 yr b p interval and two in the 2000 3000 yr b p time interval calibrated radiocarbon years there was one giant storm in the pre 5000 yr b p interval a sea level oscillation in the 3500 5000 yr b p interval appears to have destroyed most records during that period previous work suggests that the position of the bermuda or azores high influences the direction of general storm paths for major north atlantic hurricanes a position of the bermuda high farther to the south tends to force storms into the gulf of mexico whereas a northern position allows them to track up the atlantic coast results here combined with results of other workers on the gulf coast suggest a more southern position for the bermuda high causing more storms on the gulf coast in the interval of 1000 3400 yr b p conversely a more northern position during the past 1000 yr is suggested to have contributed to higher frequencies of storms on the atlantic coast in that period to test this hypothesis modern records of the movement of the north atlantic oscillation nao which controls the position of the bermuda high have been compared with historical records of hurricane tracks over the twentieth century there does appear to be a strong correlation between the position of the nao and the track the storms have pursued in modern times

dynamic response of oceanic hydrate deposits to ocean temperature change the dynamic response of oceanic hydrate deposits to ocean temperature change matthew t reagan and george j moridis earth sciences division lawrence berkeley national laboratory 1 cyclotron rd berkeley ca 94720 usa

earthquake size frequency relations from an analytical stochastic rupture model an analytical stochastic model of earthquake rupture is presented although the general formulation makes no a priori self similarity assumption scale independent earthquake size frequency esf statistics emerge from the interaction between fault strength heterogeneity and rupture mechanics the model also gives theoretical derivations for scale dependent esf statistics including gradual frequency saturation for small earthquakes and a continuum of possible transitions in the statistics of large earthquakes a model fault is characterized as a surface composed of a large number of asperities defined as small discrete contact surfaces of finite strength an earthquake rupture grows via successive asperity breaking subevents the probability of rupture to a certain size earthquake or greater is the total product of incremental rupture growth probabilities these are governed by a new asperity failure probability distribution derived as a mixture of weibull distributions by including fracture mechanics the resulting mixture distribution characterized by the scale and shape parameters and is written in terms of the rupture size the important difference between the mixture distribution and the weibull distribution is that the mixture results in power law esf statistics self similarity occurs when material heterogeneity and rupture mechanics are mutually tuned to give 1 frequency saturation for small earthquakes is shown to be a simple consequence of a general aseismic nucleation process the nucleation magnitude m defines the roll off point in esf statistics that occurs when the area of seismic rupture equals the area of precursory aseismic rupture growth by fitting the model to the parkfield earthquake data set m 0 9 is obtained the change in esf scaling for the transition from moderate to large earthquakes depends on the changes in stress at the growing rupture front the northern california earthquake data center seismicity data set is fitted for a transition at magnitude m 5 with 0 4 and 0 75 this result indicates that the change in the esf relation associated with the transition from moderate to large earthquakes in california and nevada is caused by surface rupture accompanied by partial width and slip saturation

a simplified spring block model of earthquakes the time interval between earthquakes is much larger than the actual time involved during slip in an individual event the authors have used this fact to construct a cellular automaton model of earthquakes this model describes the time evolution of a 2 d system of coupled masses and springs sliding on a frictional surface the model exhibits power law frequency size relations and can exhibit large earthquakes with the same scatter in the recurrence time observed for actual earthquakes

time dependent response of the global ocean clathrate reservoir to climatic and anthropogenic forcing 1 buffett and archer 2004 showed a model of the steady state global ocean clathrate reservoir that reproduces drill data and predicts a global methane inventory of about 5000 gton c the model inventory is very sensitive to ocean temperature with factor of two changes in methane inventory in response to temperature changes of 1 5 c here we explore the potential time dependent behavior of the clathrate reservoir assuming simple first order rate constants for methane accumulation and meltdown in response to changes in the predicted steady state reservoir for melting we divide the reservoir into two parts one melting catastrophically and the other slowly evolution of clathrates through geologic time is very sensitive to the choice of these rate constants a positive feedback exists during a transient meltdown event stronger if the catastrophic melting fraction is high and its melting timescale is fast a clathrate reservoir governed by such kinetics would melt down periodically on a multimillion year timescale determined by the rate constant for clathrate accumulation ideally we would like a model that predicts runaway melting in the paleocene and stability in the pleistocene however the model is most unstable when climate is cold rather than warm opting for stability in the pleistocene constrains the melting kinetic parameters leaving one degree of freedom the grow in timescale must be 5 myr or longer to get the deglacial 13c right but shorter than 10 myr in order for clathrates to have built up through geologically recent cooling the model thus constrained predicts methane fluxes of 200 gton c or less on deglaciations but eventual releases of 2000 4000 gton c in response to a 2000 gton c anthropogenic carbon release anthropogenic climate change differs from a deglaciation in that it warms the ocean to temperatures not seen in millions of years

statistical physics approach to understanding the multiscale dynamics of earthquake fault systems 1 earthquakes and the faults upon which they occur interact over a wide range of spatial and temporal scales in addition many aspects of regional seismicity appear to be stochastic both in space and time however within this complexity there is considerable self organization we argue that the occurrence of earthquakes is a problem that can be attacked using the fundamentals of statistical physics concepts of statistical physics associated with phase changes and critical points have been successfully applied to a variety of cellular automata models examples include sandpile models forest fire models and particularly slider block models these models exhibit avalanche behavior very similar to observed seismicity a fundamental question is whether variations in seismicity can be used to successfully forecast the occurrence of earthquakes several attempts have been made to utilize precursory seismic activation and quiescence to make earthquake forecasts some of which show promise

eigenpatterns in southern california seismicity 1 earthquakes in seismically active regions of the world are known to be associated with a variety of spatial and temporal patterns examples include precursory quiescence or activation seismic clustering and mogi donuts although the characteristics of these patterns can be qualitatively described a systematic quantitative analysis has proved elusive in this paper we employ a new method developed using numerical simulations that allows a systematic quantification of the spatial and temporal characteristics of the patterns in historic seismicity in southern california this method decomposes a set of boolean activity functions representing historic seismicity into their orthonormal eigenvalues and eigenfunctions here we show the results of this analysis which strongly support the hypothesis that seismic activity is highly correlated across many space scales and timescales within large volumes of the earth s crust

pilot study of fossil evidence of onshore directed storm events in estuarine sediments chezzetcook inlet nova scotianatural resources canada climate change impacts and adaptation program sst 20090027 sediment cores collected from the landward side of a baymouth barrier in a lower estuarine environment of chezzetcook inlet contain proxy signals of onshore directed storms that are manifested by the sudden appearance of benthic and planktic foraminifera species these taxa have been eroded and transported from adjacent inner shelf open marine environments one relatively strong onshore directed storm hurricane event appears to have caused a reduction in seawater exchange in the southeastern part of the inlet that persisted for at least several decades in this particular barrier protected lower estuarine depositional environment foraminiferal storm indicator species distributions in older sediments seem to be spatially patchy consequently in this chezzetcook depositional setting the successful reconstruction of a complete proxy storm record will require replicate coring and high frequency core subsampling strategies

foraminifera and tidal notches dating neotectonic events at korphos greece abstract fossil assemblages of foraminifera and thecamoebians from three salt marsh cores recovered at korphos greece provided evidence for five transgression events since the mid holocene marsh accretion rates based on radiocarbon dated peat and geomorphic evidence from a series of discrete v shaped submerged tidal notches indicated that these transgression events were rapid and episodic correlation of the tidal notches with the transgression horizons in the salt marsh stratigraphy revealed a stepwise pattern of relative sea level change at korphos which is best explained by coseismic subsidence related to fault displacement earthquakes associated with the hellenic subduction zone a comparison between the korphos data and a model of holocene sea level change for the peloponnesus reinforces this interpretation as sea level rose in a series of jumps by amounts greater than accounted for by eustatic and glacio hydro isostatic factors up to 2 0 m this study illustrates that by combining microfossil sedimentary and geomorphic records of past sea level change problems frequently encountered with each record individually e g dating submerged notches and autocompaction of marsh sediments may be overcome

changes in frequency size relationship from small to large earthquakes the constant b value observed in frequency magnitude distributions of earthquakes has been taken as an indication of self similarity at all magnitudes hence earthquake properties should scale uniformly in the same way from small to large earthquakes it has often been observed however that the seismic moment released in small earthquakes scales differently with rupture length than it does for large events1 2 where the crossover between small and large events is defined at a rupture dimension equal to the down dip width of the seismogenic zone a possible explanation for this contradiction is that frequency size distributions are biased by small earthquakes small events dominate most global earthquake catalogues because of the short time period covered another source of bias in size distributions is the saturation of earthquake magnitudes for large events here we correct biases in calculations of b values and present evidence for a change in b value in frequency size distributions we find that a break in self similarity from small to large earthquakes occurs at a point where the dimension of the event equals the down dip width of the seismogenic layer

a review of the ecological and taphonomic controls on foraminiferal assemblage development in intertidal environments intertidal foraminifera from surface sediments are commonly used as a high resolution indicator of sea level change the integrity of this approach is based upon the assumption that surface assemblages are similar in composition to their buried fossil counterparts this assumption may in some cases be inappropriate due to subsurface or infaunal production and taphonomic alteration here we review the current understanding of foraminiferal production and taphonomic loss in intertidal environments and examine the extent to which these processes can affect the development of foraminiferal assemblages in intertidal environments as a sediment layer undergoes burial dead tests are added at a rate proportionate to the standing crop at that depth as a consequence test accumulation within the layer is proportionate to the depth integrated standing crop depending on the nature of its vertical living distribution the upper 1 cm of sediment may therefore not adequately characterise a given species total input instead a comparison of each species contribution to the entire depth integrated living community may offer a better a priori estimate of relative input to the sediment column this provides an improved base line for identifying true taphonomic trends downcore the potential for infauna to create discrepancies between surface and subsurface assemblages may be minimised however where 1 reproduction is concentrated near to the sediment surface transforming an apparent infaunal standing crop into an effective epifaunal production 2 the living fauna is composed similarly at all depths of production and or 3 intense bioturbation homogenises the upper sediment layers the likely decline in the intensity of taphonomic processes with depth may mean that the foraminiferal production from different depths may not experience taphonomic processes uniformly consequently in addition to their possible gradual enrichment due to subsurface production infaunal species may be preferentially preserved by virtue of their production closer to the base of the taphonomically active zone additionally homogenisation of the sediment column by reworking may mix temporally and perhaps environmentally distinct faunas affecting the stratigraphic integrity of the sediment deposit the most important taphonomic processes in intertidal environments are those associated with early diagenesis while the organic cements of agglutinated taxa may be directly oxidised the associated changes in the saturation state of porewaters with respect to calcium carbonate may affect calcareous species the type of diagenetic reaction operating within the sediment provides a quantitative control on agglutinated test degradation but a largely qualitative control on calcareous preservation in addition calcareous test preservation is dependent upon the rate with which organic matter is supplied while agglutinated test preservation is independent of organic matter concentrations although the specific morphological pathways of test degradation for calcareous species are well understood the stages under which agglutinated tests are lost are less clear the combined but varying influences of production infaunal and species composition taphonomic processes and bioturbation may create complex pathways in the transition from live to dead to fossil assemblages understanding the extent to which infauna taphonomic loss and sediment reworking affect assemblage development in different intertidal environments is essential in order to interpret the fossil record

critical point theory of earthquakes observation of correlated and cooperative behavior on earthquake fault systems 1 the critical point theory for earthquakes was originally proposed to explain the scaling relations observed in earthquakes including the gutenberg richter frequency magnitude relation and the omori s law for aftershocks in this model main shocks their foreshocks and aftershocks are all associated with the formation of a correlated cooperative spatial region with high stress until now only indirect evidence of the existence of these correlated regions has been reported here in this paper we present observations and analyses that allow us to directly map the high stress spatially correlated regions preceding four major earthquakes i e the 1992 landers california 1995 kobe japan 1999 chi chi taiwan and 1999 hector mine california earthquakes we therefore conclude that the locations and extent of large main shocks and their immediate aftershocks can be determined from seismicity data taken prior to the main shocks and provide additional evidence in support of the critical point theory for earthquakes

a decadally resolved paleohurricane record archived in the late holocene sediments of a florida sinkhole article i nfo a 4500 year record of hurricane induced storm surges is developed from sediment cores collected from a coastal sinkhole near apalachee bay florida recent deposition of sand layers in the upper sediments of the pond was found to be contemporaneous with significant historic storm surges at the site modeled using slosh and the best track post 1851 a d dataset using the historic portion of the record for calibration paleohurricane deposits were identified by sand content and dated using radiocarbon based age models marine indicative foraminifera some originating at least 5 km offshore were present in several modern and ancient storm deposits the presence and long term preservation of offshore foraminifera suggest that this site and others like it may yield promising microfossil based paleohurricane reconstructions in the future due to the sub decadal 7 years resolution of the record and the site s high susceptibility to hurricane generated storm surges the average local frequency of recorded events approximately 3 9 storms per century is greater than that of previously published paleohurricane records from the region the high incidence of recorded events permitted a time series of local hurricane frequency during the last five millennia to be constructed variability in the frequency of the largest storm layers was found to be greater than what would likely occur by chance alone with intervals of both anomalously high and low storm frequency identified however the rate at which smaller layers were deposited was relatively constant over the last five millennia this may suggest that significant variability in hurricane frequency has occurred only in the highest magnitude events the frequency of high magnitude events peaked near 6 storms per century between 2800 and 2300 years ago high magnitude events were relatively rare with about 0 3 storms per century occurring between 1900 and 1600 years ago and between 400 and 150 years ago a marked decline in the number of large storm deposits which began around 600 years ago has persisted through present with below average frequency over the last 150 years when compared to the preceding five millennia

a renormalization group approach to the stick slip behavior of faults we treat a fault as an array of asperities with a prescribed statistical distribution of strengths when an asperity fails the stress on the failed asperity is transferred to one or more adjacent asperities for a linear array the stress is transferred to a single adjacent asperity and for a two dimensional array to three adjacent asperities using a renormalization group rg method we investigate the properties of a scale invariant hierarchical model for the stochastic growth of fault breaks through induced failure by stress transfer an extrapolation to arbitrarily large scales shows the existence of a critical applied stress at which the solutions bifurcate at stresses less than the critical stress virtually no asperities fail on a large scale and the fault is locked above the critical stress asperity failure cascades away from the nucleus of failure we interpret this catastrophic failure as an earthquake and it corresponds to the transition from stick to slip behavior on the fault thus the stick slip behavior of most faults can be attributed to the distribution of asperities on the fault we propose our stochastic mechanism as an alternative to the traditional hypotheses for the stick slip behavior of faults a major advantage of our approach is the inclusion of scale invariance thus the observed frequency magnitude relation for seismicity is a natural consequence of our basic hypothesis

earthquake failure sequences along a cellular fault zone in a three dimensional elastic solid containing asperity and nonasperity regions numerical simulations of earthquake failure sequences along a discrete cellular fault zone are performed for a three dimensional 3 d model representing approximately the central san andreas fault the model consists of an upper crust overlying a lower crust and mantle region together defining an elastic half space with a vertical half plane fault the fault contains a region where slip is calculated on a uniform grid of cells governed by a static kinetic friction law and regions where slip is prescribed so as to represent tectonic loading aseismic fault creep and adjacent great earthquakes the computational region models a 70 km long and 17 5 km deep section of the san andreas fault to the nw of the great 1857 rupture zone different distributions of stress drops on failing computational cells are used to model asperity parkfield asperity and nonasperity fault regions the model is inherently discrete and corresponds to a situation in which a characteristic size of geometric disorder within the fault i e cell size here a few hundreds of meters is much larger than the nucleation size of the order of tens of centimeters to tens of meters based on slip weakening or state evolution slip distances the computational grid is loaded by a constant plate motion imposed at the lower crust upper mantle and creeping fault regions and by a staircase slip history imposed at the 1857 and 1906 rupture zones stress transfer along and outside the fault due to the imposed loadings and failure episodes along the computational grid is calculated using 3 d elastic dislocation theory the resulting displacement field in the computational region is compatible with geodetic and seismological observations only when the asperity and nonasperity regions are characterized by significantly different average stress drops the frequency magnitude statistics of the simulated failure episodes are approximately self similar for small events with b 1 2 the b value of statistics based on rupture area ba is about 1 but are strongly enhanced with respect to self similarity for events larger than a critical size this is interpreted as a direct manifestation of our 3 d elastic stress transfer calculations beyond certain rupture area and potency seismic moment divided by rigidity release values the event is usually unstoppable and it continues to grow to a size limited by a characteristic model dimension this effect is not accounted for by cellular automata and block spring models in which the adopted simplified stress transfer laws fail to scale properly with increasing rupture size the simulations suggest that local maxima in observed frequency magnitude statistics correspond to dimensions of coherent brittle zones such as the width of the seismogenic layer or the length of a fault segment bounded by barriers the analysis indicates that a single cell size representing approximately a single scale of geometric disorder cannot induce self similarity in a 3 d elastic model over a broad range of magnitudes a representation of geometric disorder covering a range of scales may thus be required to generate a wide domain of self similar gutenberg richter statistics our simulations show a great diversity in the mode of failure of the parkfield asperity the earthquakes themselves define an irregular sequence of events the modeling like many other discrete fault models suggests that expectations for periodic parkfield earthquakes and or simple precursory patterns repeating from one event to the other are unrealistic

contrasting sediment records of marine submersion events related to wave exposure southwest france abstract sediment records of two contrasting backshore coastal marshes extremely vulnerable to recent and historical marine flooding events located on the sw coast of france have been investigated using a multiproxy approach the studied marshes are 30 km apart and have been flooded by similar storm events 7 marine floods in the last 250 years one is located in a wave exposed coast but isolated from the sea by a sediment barrier whereas the other is located in a sheltered estuarine environment and isolated from the sea by a dike one core was collected in each marsh and information on grain size foraminifera shell contents and stable carbon isotopes was obtained along with an age model using 210 pb 137 cs and 14 c core data combined with historical maps give evidence of a typical estuarine backfilling part of the holocene regressive parasequence including an intertidal mudflat at the base and a backshore environment at the top despite the absence of grain size anomalies marine flood related sedimentation in the backshore area of both marshes is identified by a mixture of marine and terrestrial features including marine fauna vegetation debris and variation in the 13 c signature of the organic fraction very low sedimentation rates between flood events and or bioturbation prevents the identification of individual episodic marine floods in the sediment succession comparison of the two sedimentary successions shows that the foraminifera deposited by marine submersions are of two different types foraminifera are monospecific and originate from the upper tidal mudflat in the sheltered marsh whereas in the backshore marsh located in a wave exposed environment they show higher diversity and originate from both shallow and deeper water marine environments this study shows that wave exposure can control the faunal content of marine flood sediment records in coastal marshes

contrasting styles of hurricane irene washover sedimentation on three east coast barrier islands cape lookout north carolina assateague island virginia and fire island new york abstract storm surge and wind driven waves generated by hurricane irene which made landfall on the u s east coast on august 27 2011 resulted in overwash of sandy barrier islands from north carolina to new york state overwash has significant impacts on barrier island geomorphology it represents a sediment pathway into island interiors a component of island sediment budgets and can cause considerable aggradation of backshore surfaces important for potentially offsetting the effects of rising sea level this study describes the morphology texture and microfossil content of hurricane irene washover deposits at three contrasting barrier island sites cape lookout north carolina assateague island virginia and fire island new york at all three sites run up overwash occurred wherein waves were sufficient to overtop parts of the beach system and transport sediment inland however at fire island overwash was restricted by a higher elevational threshold to low spots in the beach system coinciding with pre existing breaches in foredunes the result was the formation of isolated thinner low volume washover fans at assateague island and cape lookout lower elevational thresholds allowed waves to overtop longer continuous sections of beach systems resulting in the formation of laterally continuous thicker larger volume washover terraces overall the deposits lacked consistent trends in thickness and texture such as thinning and fining inland reflecting a progressive reduction in overwash competence thickness and texture of the deposits were both spatially variable and probably reflect infilling of low points on the former surface and the influence of beach and foredune sediment sources all the washover deposits were essentially barren of foraminiferal microfossils supporting the textural evidence that the adjacent beach and foredunes were the predominant sediment sources

microfossils from coastal environments as indicators of paleo earthquakes tsunamis and storms abstract coastal risk assessment and hazard mitigation require datasets on centennial and millennial temporal scales to capture natural variability and multiple occurrences of the largest but least frequent events coastal sediments from low energy depositional environments archive geologic evidence of paleo earthquakes tsunamis and storms many of the best reconstructions of these events are derived from changes in microfossil diatoms foraminifera and pollen assemblages in this review we explain how microfossils are used to reconstruct records of paleoearthquakes by quantifying the amount of coseismic and interseismic vertical land movements along tectonically active coastlines examples from the united states alaska and the pacific northwest japan and chile show that microfossil based transfer functions may provide continuous records of vertical land movement during earthquake deformation cycles we discuss how microfossil habitat preferences and taphonomic character are used to constrain sediment provenance e g beach nearshore or offshore sources and identify overwash deposits and how this information can be used to reconstruct the recurrence of tsunamis and storms analysis of overwash deposits from thailand and malaysia indicates the ability of microfossils to resolve individual waves within tsunami sediments and an example from the sendai coastal plain in japan uses foraminifera to ascribe a beach to nearshore provenance for the 2011 tohoku tsunami deposit finally we present recent examples from the gulf of mexico on the use of foraminifera to estimate the volume and distance of transport of storm overwash from hurricanes

tsunami sediments and their foraminiferal assemblages abstract tsunami hazard assessment begins with a compilation of past events that have affected a specific location given the inherent limitations of historical archives the geological record has the potential to provide an independent dataset useful for establishing a richer chronologically deeper time series of past events recent geological studies of tsunami are helping to improve our understanding of the nature and character of tsunami sediments wherever possible geologists should be working to improve the research tool kit available to identify past tsunami events marine foraminifera single celled heterotrophic protists have often been reported as present within tsunami deposited sediments but in reality little information about environmental conditions and by analogy the tsunami that deposited them has been reported even though foraminifera have an enormous capacity to provide meaningful palaeo environmental data here we review what foraminifera are describe their basic form and significance summarise where they have been reported in tsunami sediments and identify what can be learnt from them we review the gaps in our understanding and make recommendations to assist researchers who examine foraminiferal assemblages in order to enhance their use within tsunami geology

physical basis for statistical patterns in complex earthquake populations models predictions and tests understanding the physics of earthquakes and the space time patterns they produce is illuminated by the use of coarse grained models and simulations that capture the basic physical processes and that are amenable to analysis we present a summary of ideas that describe the nucleation growth and arrest of earthquakes on individual faults under shear loading we find that faults reside in a metastable state near a classical spinodal that governs the nucleation and growth of slip events the roughness of an associated stress distribution field x t determines whether slip events are confined within the initial high stress patch or break away and grow to become very large we find a critical value of roughness that is associated with a first order order disorder transition we also give a number of predictions examples and applications of these ideas and indicate how they might be tested through systematic observational programs

low sea level emplacement of a very large late pleistocene megaturbidite in the western mediterranean sea large volume turbidites termed megaturbidites or megabeds result from catastrophic slope failures and the associated downslope transport of enormous quantities of sediment from continental margins to the deep sea such large sediment failures can generate tsunamis and in terrains underlain by gas hydrates clathrates may be associated with the release of substantial amounts of the greenhouse gas methane it has been proposed that the megaturbidite events may be triggered by seismic activity or may result from gas hydrate release itself caused by a lowering of hydrostatic pressure on clathrates as a result of low sea level previous conclusions on the significance of sea level change however have been conditional because of the lack of absolute times of turbidite emplacement here we use accelerator mass spectrometry radiocarbon dating in five widely spaced cores to constrain the date of emplacement of a large volume 500 km3 bed in the balearic basin of the western mediterranean this turbidite is exceptional in its magnitude and represents the main sedimentation event in the balearic basin over the past 100 kyr our data provide an estimate of 22 000 calendar years before present for emplacement of the megabed a time when sea level stood at its lowest level during the last glacial maximum the coincidence of these dates is consistent with emplacement due to clathrate destabilization caused by low sea level although other triggering mechanisms such as seismic shock cannot be ruled out

assessing the suitability of holocene environments along the central belize coast central america for the reconstruction of hurricane records since the belize coast was repeatedly affected by hurricanes and the paleohurricane record for this region is poor sediment cores from coastal lagoon environments along the central belize coast have been examined in order to identify storm deposits the paleohurricane record presented in this study spans the past 8000 years and exhibits three periods with increased evidences of hurricane strikes occurring at 6000 4900 4200 3600 and 2200 1500 cal yr bp two earlier events around 7100 and 7900 cal yr bp and more recent events around 180 cal yr bp and during modern times have been detected sand layers redeposited corals and lagoon shell concentrations have been used as proxies for storm deposition additionally hiatuses and reversed ages may indicate storm influence while sand layers and corals represent overwash deposits the lagoon shell concentrations which mainly comprise the bivalve anomalocardia cuneimeris and cerithid gastropods have been deposited due to changes in lagoon salinity during and after storm landfalls comparison with other studies reveals similarities with one record from belize but hardly any matches with other published records the potential for paleotempestology reconstructions of the barrier lagoon complexes along the central belize coast differs depending on geomorphology and deposition of washovers in the lagoon basins is limited probably due to the interplay of biological geological and geomorphological processes

proxy records of holocene storm events in coastal barrier systems storm wave induced markers abstract extreme storm events in the coastal zone are one of the main forcing agents of short term coastal system behavior as such storms represent a major threat to human activities concentrated along the coasts worldwide in order to better understand the frequency of extreme events like storms climate science must rely on longer time records than the century scale records of instrumental weather data proxy records of storm wave or storm wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia this review provides a detailed state of the art compilation of the proxies available from coastal barrier systems to reconstruct holocene storm chronologies paleotempestology the present paper aims i to describe the erosional and depositional processes caused by storm wave action in barrier and back barrier systems i e beach ridges storm scarps and washover deposits ii to understand how storm records can be extracted from barrier and back barrier sedimentary bodies using stratigraphical sedimentological micro paleontological and geochemical proxies and iii to show how to obtain chronological control on past storm events recorded in the sedimentary successions the challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm chronologies using these various proxies are discussed and future research prospects are outlined

2500 year paleotempestological record of intense storms for the northern gulf of mexico united states abstract the northern gulf of mexico has been devastated by recent intense storms camille 1969 and katrina 2005 are two notable hurricanes that made landfall in nearly the same location in mississippi fully understanding the risks and processes associated with hurricane impacts are impeded by a short and fragmented instrumental record however paleotempestology has the potential to employ modern analogues from intense storms in this region to extend the hurricane record beyond pre observational time existing empirically based models can back calculate surge heights over coastal systems as a function of transport distance particle settling velocity and gravitational acceleration we collected sediment cores in a pond 3 and adjacent beach 1 in hancock county mississippi grain size loss on ignition and microfossil analyses were conducted on cores in the context of a bayesian statistical age model using 137cs and 14c dating using hurricane camille to calibrate the archive similar coarse grained deposits were identified and inverse sediment transport models calculated paleosurge intensities similar in magnitude to camille over the 2500 yr record our multi millennial annual average landfall probability 0 48 closely matches previously published studies from the gulf of mexico indicating that intense hurricanes have not varied over these timescales over centennial timescales active intervals occurred between 900 to 600 and 2200 to 1900 yr bp with relative quiescence between 1900 to 900 yr bp comparisons with other published sites support the notion that southerly shifts in the loop current may be responsible for the decline in activity around 600 yr bp