analyzing earthquake clustering features by using stochastic reconstruction 1 on the basis of the epidemic type aftershock sequence etas model and the thinning procedure this paper gives the method about how to classify the earthquakes in a given catalogue into different clusters stochastically the key points of this method are the probabilities of one event being triggered by another previous event and being a background event making use of these probabilities we can reconstruct the functions associated with the characteristics of earthquake clusters to test a number of important hypotheses about the earthquake clustering phenomena we applied this reconstruction method to the shallow seismic data in japan and also to a simulated catalogue the results show the following assertions 1 the functions for each component in the formulation of the space time etas model are good enough as a first order approximation for describing earthquake clusters 2 a background event triggers less offspring in expectation than a triggered event of the same magnitude 3 the magnitude distribution of the triggered event depends on the magnitude of its direct ancestor 4 the diffusion of the aftershock sequence is mainly caused by cascades of individual triggering processes while no evidence shows that each individual triggering process is diffusive and 5 the scale of the triggering region is still an exponential law as formulated in the model but not the same one for the expected number of offspring

global earthquake forecasts summary we have constructed daily worldwide long and short term earthquake forecasts these forecasts specify the earthquake rate per unit area time and magnitude on a 0 5 degree grid for a global zone region between 75n and 75s latitude 301 by 720 grid cells we use both the global centroid moment tensor gcmt and preliminary determinations of epicenters pde catalogues like our previous forecasts the new forecasts are based largely on smoothed maps of past seismicity and assume spatial and temporal clustering the forecast based on the gcmt catalogue with the magnitude completeness threshold 5 8 includes an estimate of focal mechanisms of future earthquakes and of the mechanism uncertainty the forecasted tensor focal mechanism makes it possible in principle to calculate an ensemble of seismograms for each point of interest on the earth s surface we also introduce a new approach that circumvents the need for focal mechanisms this permits the use of the pde catalogue that reliably documents many smaller quakes with a higher location accuracy the result is a forecast at a higher spatial resolution and down to a magnitude threshold below 5 0 such new forecasts can be prospectively tested within a relatively short time such as a few years because smaller events occur with greater frequency the forecast s efficiency can be measured by its average probability gains per earthquake compared to the spatially or temporally uniform poisson distribution for the short term forecast the gain is about 2 0 for the gcmt catalogue and 3 7 for the pde catalogue relative to a temporally random but spatially localized null hypothesis preliminary tests indicate that for the long term global spatial forecast the gain is of the order 20 25 compared to the uniform event distribution over the earth s surface we can also prospectively test the long term forecast to check whether it can be improved

variability of el nino southern oscillation activity at millennial timescales during the holocene epoch the variability of el nino southern oscillation enso during the holocene epoch in particular on millennial timescales is poorly understood palaeoclimate studies have documented enso variability for selected intervals in the holocene but most records are either too short or insufficiently resolved to investigate variability on millennial scales1 2 3 here we present a record of sedimentation in laguna pallcacocha southern ecuador which is strongly influenced by enso variability and covers the past 12 000 years continuously we find that changes on a timescale of 2 8 years which we attribute to warm enso events become more frequent over the holocene until about 1 200 years ago and then decline towards the present periods of relatively high and low enso activity alternating at a timescale of about 2 000 years are superimposed on this long term trend we attribute the long term trend to orbitally induced changes in insolation and suggest internal enso dynamics as a possible cause of the millennial variability however the millennial oscillation will need to be confirmed in other enso proxy records

enso reconstructions over the past 60 ka using giant clams tridacna sp from papua new guinea we present 12 seasonally resolved delta o 18 profiles of giant clams tridacna sp from the huon peninsula papua new guinea spanning discrete periods of time 9 38 years over the past 60 ka the interannual anomaly time series of these shells are used to reconstruct interannual variability which can predominantly be attributed in the modern climate to the el nino southern oscillation enso in this region we have found a significant reduction in interannual delta o 18 variance during the early holocene whereas during marine isotope stage 3 there were at least some periods with variance not significantly different to the twentieth century we show that enso variability seen during the late twentieth century is rare but not unprecedented within glacial climates

real time earthquake forecasting in italy abstract we have applied an earthquake clustering epidemic model to real time data at the italian earthquake data center operated by the istituto nazionale di geofisica e vulcanologia ingv for short term forecasting of moderate and large earthquakes in italy in this epidemic type model every earthquake is regarded at the same time as being triggered by previous events and triggering following earthquakes the model uses earthquake data only with no explicit use of tectonic geologic or geodetic information the forecasts are displayed as time dependent maps showing both the expected rate density of m l 4 0 earthquakes and the probability of ground shaking exceeding modified mercalli intensity vi pga 0 01 g in an area of 100 100 km 2 around the zone of maximum expected rate density in the following 24 h for testing purposes the overall probability of occurrence of an m l 4 5 earthquake in the same area of 100 100 km 2 is also estimated the whole procedure is tested in real time for internal use only at the ingv earthquake data center forecast verification procedures have been carried out in forward retrospective way on the 2006 2007 ingv data set making use of statistical tools as the relative operating characteristics roc diagrams these procedures show that the clustering epidemic model performs up to several hundred times better than a simple random forecasting hypothesis the seismic hazard modeling approach so developed after a suitable period of testing and refinement is expected to provide a useful contribution to real time earthquake hazard assessment even with a possible practical application for decision making and public information

probabilistic forecasting of earthquakes we present long term and short term forecasts for magnitude 5 8 and larger earthquakes we discuss a method for optimizing both procedures and testing their forecasting effectiveness using the likelihood function our forecasts are expressed as the rate density that is the probability per unit area and time anywhere on the earth our forecasts are for scientific testing only they are not to be construed as earthquake predictions or warnings and they carry no official endorsement for our long term forecast we assume that the rate density is proportional to a smoothed version of past seismicity using the harvard cmt catalogue this is in some ways antithetical to the seismic gap model which assumes that recent earthquakes deter future ones the estimated rate density depends linearly on the magnitude of past earthquakes and approximately on a negative power of the epicentral distance out to a few hundred kilometres we assume no explicit time dependence although the estimated rate density will vary slightly from day to day as earthquakes enter the catalogue the forecast applies to the ensemble of earthquakes during the test period it is not meant to predict any single earthquake and no single earthquake or lack of one is adequate to evaluate such a hypothesis we assume that 1 per cent of all earthquakes are surprises assumed uniformly likely to occur in those areas with no earthquakes since 1977 we have made specific forecasts for the calendar year 1999 for the northwest pacific and southwest pacific regions and we plan to expand the forecast to the whole earth we test the forecast against the earthquake catalogue using a likelihood test and present the results our short term forecast updated daily makes explicit use of statistical models describing earthquake clustering like the long term forecast the short term version is expressed as a rate density in location magnitude and time however the short term forecasts will change significantly from day to day in response to recent earthquakes the forecast applies to main shocks aftershocks aftershocks of aftershocks and main shocks preceded by foreshocks however there is no need to label each event and the method is completely automatic according to the model nearly 10 per cent of moderately sized earthquakes will be followed by larger ones within a few weeks

second round of evaluations of proposed earthquake precursors this review summarizes the result of the second round of nominations for the iaspei preliminary list of significant precursors currently this list contains five cases of precursors 1 foreshocks 2 preshocks 3 seismic quiescence before major aftershocks 4 radon decrease in ground water and 5 ground water level increase a list of four cases that could not be accepted nor rejected by the panels reviewing them contains three on crustal deformations and one on seismic quiescence in the second round 10 nominations were evaluated nine new ones and one which had been considered previously two were accepted for the list two were placed in the category of undecided cases to date a total of 40 nominations have been evaluated by iaspei for 37 of these the nominations the mail reviews the panel opinions and where supplied the author s reply were published this evaluation process remains active throughout the international decade for natural hazards reduction additional nominations are invited

sedimentary processes and the distribution of tsunami deposits on a narrow coastal lowland backed by a cliff in flume experiments abstract we performed flume experiments to examine tsunami flow conditions sedimentary processes and the distribution of tsunami deposits on a narrow coastal lowland backed by a cliff the experiments directed tsunamis of eight magnitudes onto a terrestrial model of a narrow coastal plain backed by a cliff and the results were compared with those of similar previously conducted experiments without a cliff in the experimental series with the cliff the tsunami flow was blocked and pooled and as a consequence the flow changed from supercritical to subcritical with a hydraulic jump the flow transformation forced the suspended sediment in the subsequent flow to stall and deposit as a result the distribution of deposits show a local maximum at a short distance from the cliff in particular in the case of larger tsunami flows this result suggests that an impeder such as a cliff can cause transformation of a tsunami flow and locally thick deposits

foreshock occurrence before large earthquakes rates of foreshock occurrence involving shallow m 6 and m 7 mainshocks and m 5 foreshocks were measured in two worldwide catalogs over 20 year intervals the overall rates observed are similar to ones measured in previous worldwide and regional studies when they are normalized for the ranges of magnitude difference they each span the observed worldwide rates were compared to a generic model of earthquake clustering based on patterns of small and moderate aftershocks in california the aftershock model was extended to the case of moderate foreshocks preceding large mainshocks overall the observed worldwide foreshock rates exceed the extended california generic model by a factor of 2 significant differences in foreshock rate were found among subsets of earthquakes defined by their focal mechanism and tectonic region with the rate before thrust events higher and the rate before strike slip events lower than the worldwide average among the thrust events a large majority composed of events located in shallow subduction zones had a high foreshock rate while a minority located in continental thrust belts had a low rate these differences may explain why previous surveys have found low foreshock rates among thrust events in california especially southern california while the worldwide observations suggests the opposite california lacking an active subduction zone in most of its territory and including a region of mountain building thrusts in the south reflects the low rate apparently typical for continental thrusts while the worldwide observations dominated by shallow subduction zone events are foreshock rich if this is so then the california generic model may significantly underestimate the conditional probability for a very large m 8 earthquake following a potential m 7 foreshock in cascadia the magnitude differences among the identified foreshock mainshock pairs in the harvard catalog are consistent with a uniform distribution over the range of observation

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

old radiocarbon ages in the southwest pacific ocean during the last glacial period and deglaciation marine radiocarbon 14c dates are widely used for dating oceanic events and as tracers of ocean circulation essential components for understanding ocean climate interactions past ocean ventilation rates have been determined by the difference between radiocarbon ages of deep water and surface water reservoirs but the apparent age of surface waters currently approximately 400 years in the tropics and approximately 1 200 years in antarctic waters might not be constant through time as has been assumed in radiocarbon chronologies and palaeoclimate studies here we present independent estimates of surface water and deep water reservoir ages in the new zealand region since the last glacial period using volcanic ejecta tephras deposited in both marine and terrestrial sediments as stratigraphic markers compared to present day values surface reservoir ages from 11 900 14c years ago were twice as large 800 years and during glacial times were five times as large 2 000 years contradicting the assumption of constant surface age furthermore the ages of glacial deep water reservoirs were much older 3 000 5 000 years the increase in surface to deep water age differences in the glacial southern ocean suggests that there was decreased ocean ventilation during this period

intermediate term prediction of occurrence times of strong earthquakes pattern recognition procedures for infrequent events are adapted to the problem of identifying patterns of clustering of small and intermediate scale seismicity before large earthquakes identification procedures derived from analysis of large california and nevada earthquakes yield a high success rate when applied to other parts of the world

testing an earthquake prediction algorithm a test to evaluate earthquake prediction algorithms is being applied to a russian algorithm known as m8 the m8 algorithm makes intermediate term predictions for earthquakes to occur in a large circle based on integral counts of transient seismicity in the circle in a retroactive prediction for the period january 1 1985 to july 1 1991 the algorithm as configured for the forward test would have predicted eight of ten strong earthquakes in the test area a null hypothesis based on random assignment of predictions predicts eight earthquakes in 2 87 of the trials the forward test began july 1 1991 and will run through december 31 1997 as of july 1 1995 the algorithm had forward predicted five out of nine earthquakes in the test area which success ratio would have been achieved in 53 of random trials with the null hypothesis

statistical analysis of the central europe seismicity abstract the aim of this paper is to characterize the spatio temporal distribution of central europe seismicity specifically by using a non parametric statistical approach the proportional hazard model leading to an empirical estimation of the hazard function we provide some constrains on the time behavior of earthquake generation mechanisms the results indicate that the most conspicuous characteristics of mw 4 0 earthquakes is a temporal clustering lasting a couple of years this suggests that the probability of occurrence increases immediately after a previous event after a few years the process becomes almost time independent furthermore we investigate the cluster properties of the seismicity of central europe by comparing the obtained result with the one of synthetic catalogs generated by the epidemic type aftershock sequences etas model which previously have been successfully applied for short term clustering our results indicate that the etas is not well suited to describe the seismicity as a whole while it is able to capture the features of the short term behaviour remarkably similar results have been previously found for italy using a higher magnitude threshold

development of an inshore fringing coral reef using textural compositional and stratigraphic data from magnetic island great barrier reef australia the stratigraphy of fringing coral reef environments and platforms provides unique insights into reef development and evolution this study used twelve sediment cores from three transects across a reef flat in nelly bay magnetic island ne australia to examine its development over the holocene the maximum thickness of the holocene reefal material based on seismic and bore log data was around 5 m and comparable to other fringing reefs in the great barrier reef gbr six different sedimentary facies were identified in the cores and two coincided with reef accretion the lower muddy sand with coral rubble and the upper siliciclastic sand with coral rubble radiocarbon and u series dates show that the nelly bay fringing reef initiated around 6300 yr bp on a gently sloping unconsolidated or weakly cemented pleistocene alluvial sedimentary facies the ages of four massive coral heads range between 5790 and 6290 calibrated c 14 yr bp were almost contemporaneous with reefal initiation indicating that conditions were favourable for reef growth around this time vertical accretion rates for the nelly bay fringing reef were on average about 0 5 mm yr over the last 6000 yr although rates were as high as 5 mm yr during initiation average lateral accretion rates varied from 98 to 120 mm yr which are comparable to rates of other fringing reefs in the region the age structure of the lower muddy sedimentary facies was consistent with the classic seaward prograding model of fringing reef development in contrast the upper siliciclastic sand with coral rubble facies was much younger in age 1100 yr bp than the models and appears to represent an erosional unconformity between the upper and lower reefal facies possibly linked to late holocene sea level fall this younger facies extends laterally across the reef flat and has no obvious prograding symmetry our integrated approach using multi proxy analyses of sediment cores from the nelly bay reef flat highlights the complex development of this reef which include changes in coral composition and rubble preservation reef evolution in response to sea level change and changes in reef accretion rates

holocene variability in the intensity of wind gap upwelling in the tropical eastern pacific wind driven upwelling in pacific panama is a significant source of oceanographic variability in the tropical eastern pacific this upwelling system provides a critical teleconnection between the atlantic and tropical pacific that may impact climate variability on a global scale despite its importance to oceanographic circulation ecology and climate little is known about the long term stability of the panamanian upwelling system or its interaction with climatic forcing on millennial time scales using a combination of radiocarbon and u series dating of fossil corals collected in cores from five sites across pacific panama we reconstructed the local radiocarbon reservoir correction r from 6750 cal b p to present because the r of shallow water environments is elevated by upwelling our data set represents a millennial scale record of spatial and temporal variability of the panamanian upwelling system the general oceanographic gradient from relatively strong upwelling in the gulf of panama to weak to absent upwelling in the gulf of chiriqui was present throughout our record however the intensity of upwelling in the gulf of panama varied significantly through time our reconstructions suggest that upwelling in the gulf of panama is weak at present however the middle holocene was characterized by periods of enhanced upwelling with the most intense upwelling occurring just after of a regional shutdown in the development of reefs at 4100 cal b p comparisons with regional climate proxies suggest that whereas the intertropical convergence zone is the primary control on modern upwelling in pacific panama the el nino southern oscillation drove the millennial scale variability of upwelling during the holocene

changes in north atlantic radiocarbon reservoir ages during the allerod and younger dryas estimates of the radiocarbon age of seawater are required in correlations between marine and terrestrial records of the late quaternary climate we radiocarbon dated marine shells and terrestrial plant remains deposited in two bays on norway s west coast between 11 000 and 14 000 years ago a time of large and abrupt climatic changes that included the younger dryas yd cold episode the radiocarbon age difference between the shells and the plants showed that sea surface reservoir ages increased from 400 to 600 years in the early yd stabilized for 900 years and dropped by 300 years within a century across the yd holocene transition

climate variability over the last 35 000 years recorded in marine and terrestrial archives in the australian region an oz intimate compilation abstract the australian region spans some 60 of latitude and 50 of longitude and displays considerable regional climate variability both today and during the late quaternary a synthesis of marine and terrestrial climate records combining findings from the southern ocean temperate tropical and arid zones identifies a complex response of climate proxies to a background of changing boundary conditions over the last 35 000 years climate drivers include the seasonal timing of insolation greenhouse gas content of the atmosphere sea level rise and ocean and atmospheric circulation changes our compilation finds few climatic events that could be used to construct a climate event stratigraphy for the entire region limiting the usefulness of this approach instead we have taken a spatial approach looking to discern the patterns of change across the continent the data identify the clearest and most synchronous climatic response at the time of the last glacial maximum lgm 21 3 ka with unambiguous cooling recorded in the ocean and evidence of glaciation in the highlands of tropical new guinea southeast australia and tasmania many terrestrial records suggest drier conditions but with the timing of inferred snowmelt and changes to the rainfall runoff relationships driving higher river discharge at the lgm in contrast the deglaciation is a time of considerable south east to north west variation across the region warming was underway in all regions by 17 ka post glacial sea level rise and its associated regional impacts have played an important role in determining the magnitude and timing of climate response in the north west of the continent in contrast to the southern latitudes no evidence for cooling during the younger dryas chronozone is evident in the region but the antarctic cold reversal clearly occurs south of australia the holocene period is a time of considerable climate variability associated with an intense monsoon in the tropics early in the holocene giving way to a weakened monsoon and an increasingly el nino dominated enso to the present the influence of enso is evident throughout the southeast of australia but not the southwest this climate history provides a template from which to assess the regionality of climate events across australia and make comparisons beyond our region

atmospheric 14c variations derived from tree rings during the early younger dryas abstract atmospheric radiocarbon variations over the younger dryas interval from 13 000 to 11 600 cal yr bp are of immense scientific interest because they reveal crucial information about the linkages between climate ocean circulation and the carbon cycle however no direct and reliable atmospheric 14c records based on tree rings for the entire younger dryas have been available in this paper we present 1 high precision 14c measurements on the extension of absolute tree ring chronology from 12 400 to 12 560 cal yr bp and 2 high precision high resolution atmospheric 14c record derived from a 617 yr long tree ring chronology of huon pine from tasmania australia spanning the early younger dryas the new tree ring 14c records bridge the current gap in european tree ring radiocarbon chronologies during the early younger dryas linking the floating lateglacial pine record to the absolute tree ring timescale a continuous and reliable atmospheric 14c record for the past 14 000 cal yr bp including the younger dryas is now available the new records indicate that the abrupt rise in atmospheric 14c associated with the younger dryas onset occurs at 12 760 cal yr bp 240 yrs later than that recorded in cariaco varves with a smaller magnitude of 40 followed by several centennial 14c variations of 20 25 comparing the tree ring 14c to marine derived 14c and modelled 14c based on ice core 10be fluxes we conclude that changes in ocean circulation were mainly responsible for the younger dryas onset while a combination of changes in ocean circulation and 14c production rate were responsible for atmospheric 14c variations for the remainder of the younger dryas

influence of the intertropical convergence zone on the east asian monsoon a palaeoclimate record spanning the past 16 000 years with nearly annual time resolution has been obtained from lake huguang maar in china the magnetic properties and titanium content of the lake sediments are thought to reflect changes in the east asian winter monsoon strength thus providing a complement to palaeoclimate archives that record the strength of the rain bearing summer monsoon the records point to an anti correlation between winter and summer monsoon strength best explained by migration of the intertropical convergence zone itcz a belt of low pressure air at the equator interestingly the decline of china s tang dynasty and the mayan civilization broadly coincide with drought periods recorded in lake huguang maar and cariaco basin sediments respectively did major shifts in the position of the itcz catalyse simultaneous events in civilizations on opposite sides of the pacific ocean the asian australian monsoon is an important component of the earth s climate system that influences the societal and economic activity of roughly half the world s population the past strength of the rain bearing east asian summer monsoon can be reconstructed with archives such as cave deposits1 2 3 but the winter monsoon has no such signature in the hydrological cycle and has thus proved difficult to reconstruct here we present high resolution records of the magnetic properties and the titanium content of the sediments of lake huguang maar in coastal southeast china over the past 16 000 years which we use as proxies for the strength of the winter monsoon winds we find evidence for stronger winter monsoon winds before the bolling allerod warming during the younger dryas episode and during the middle and late holocene when cave stalagmites suggest weaker summer monsoons1 2 3 we conclude that this anticorrelation is best explained by migrations in the intertropical convergence zone similar migrations of the intertropical convergence zone have been observed in central america for the period ad 700 to 900 refs 4 6 suggesting global climatic changes at that time from the coincidence in timing we suggest that these migrations in the tropical rain belt could have contributed to the declines of both the tang dynasty in china and the classic maya in central america

retrospective forecasting of m 4 0 earthquakes in new zealand we have applied a variation of the epidemic type aftershock sequence etas model which is a stochastic triggering epidemic model incorporating short term clustering to data collected by the new zealand seismological observatory wellington geonet for forecasting earthquakes of moderate and large magnitude in the new zealand region the model uses earthquake data only with no explicit use of tectonic geologic or geodetic information in this epidemic type model every earthquake is regarded at the same time as being triggered by previous events and triggering following earthquakes a maximum likelihood estimate of the model parameters has been performed on the learning period from 1960 to 2005 for earthquakes of magnitude 4 0 and larger forecast verification procedures have been carried out in a forward retrospective way on the january 2006 to april 2008 data set making use of statistical tools as the log likelihood ratio the relative operating characteristics roc diagrams the molchan error diagrams the probability gain and the r score these procedures show that the clustering epidemic model achieves a log likelihood ratio per event of the order of some units and a probability gain up to several hundred times larger than a time independent spatially uniform random forecasting hypothesis the results show also that a significant component of the probability gain is linked to the time independent spatial distribution of the seismicity used in the model

earthquake prediction a critical review summary earthquake prediction research has been conducted for over 100 years with no obvious successes claims of breakthroughs have failed to withstand scrutiny extensive searches have failed to find reliable precursors theoretical work suggests that faulting is a non linear process which is highly sensitive to unmeasurably fine details of the state of the earth in a large volume not just in the immediate vicinity of the hypocentre any small earthquake thus has some probability of cascading into a large event reliable issuing of alarms of imminent large earthquakes appears to be effectively impossible key word earthquake prediction

short term earthquake forecasting using early aftershock statistics abstract we present an alarm based earthquake forecast model that uses the early aftershock statistics east this model is based on the hypothesis that the time delay before the onset of the power law aftershock decay rate decreases as the level of stress and the seismogenic potential increase here we estimate this time delay from t g the time constant of the omori utsu law to isolate space time regions with a relative high level of stress the single local variable of our forecast model is the e a value the ratio between the long term and short term estimations of t g when and where the e a value exceeds a given threshold i e the c value is abnormally small an alarm is issued and an earthquake is expected to occur during the next time step retrospective tests show that the east model has better predictive power than a stationary reference model based on smoothed extrapolation of past seismicity the official prospective test for california started on 1 july 2009 in the testing center of the collaboratory for the study of earthquake predictability csep during the first nine months 44 m 4 earthquakes occurred in the testing area for this time period the east model has better predictive power than the reference model at a 1 level of significance because the east model has also a better predictive power than several time varying clustering models tested in csep at a 1 level of significance we suggest that our successful prospective results are not due only to the space time clustering of aftershocks

testing earthquake prediction methods the west pacific short term forecast of earthquakes with magnitude mwhrv 5 8 in his paper kossobokov investigates the e ciency of our short term forecast for two western paciflc regions although we agree with the basic results of his evaluation that the forecast statistics is much better than a random guess we have reservations about his deflnition of earthquake prediction some of his tests and his interpretation of the test results we distinguish between deterministic earthquake predictions and statistical forecasts we argue that some techniques used by kossobokov may not be appropriate for testing our forecasts and discuss other testing methods based on the likelihood function we demonstrate that kossobokov s null hypothesis may be biased and this bias can in uence some of his conclusions we show that contrary to kossobokov s statement our algorithm predicts mainshocks when they are preceded by foreshocks

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

a poisson model for earthquake frequency uncertainties in seismic hazard analysis 1 frequency magnitude distributions and their associated uncertainties are of key importance in statistical seismology when fitting these distributions the assumption of gaussian residuals is invalid since event numbers are both discrete and of unequal variance in general the observed number in any given magnitude range is described by a binomial distribution which given a large total number of events of all magnitudes approximates to a poisson distribution for a sufficiently small probability associated with that range in this paper we examine four earthquake catalogues new zealand institute of geological and nuclear sciences southern california southern california earthquake center the preliminary determination of epicentres and the harvard centroid moment tensor both held by the united states geological survey using independent poisson distributions to model the observations we demonstrate a simple way of estimating the uncertainty on the total number of events occurring in a fixed time period

post glacial sea level changes around the australian margin a review abstract it has been known since rhodes fairbridge s first attempt to establish a global pattern of holocene sea level change by combining evidence from western australia and from sites in the northern hemisphere that the details of sea level history since the last glacial maximum vary considerably across the globe the australian region is relatively stable tectonically and is situated in the far field of former ice sheets it therefore preserves important records of post glacial sea levels that are less complicated by neotectonics or glacio isostatic adjustments accordingly the relative sea level record of this region is dominantly one of glacio eustatic ice equivalent sea level changes the broader australasian region has provided critical information on the nature of post glacial sea level including the termination of the last glacial maximum when sea level was approximately 125 m lower than present around 21 000 19 000 years bp and insights into meltwater pulse 1a between 14 600 and 14 300 cal yr bp although most parts of the australian continent reveals a high degree of tectonic stability research conducted since the 1970s has shown that the timing and elevation of a holocene highstand varies systematically around its margin this is attributed primarily to variations in the timing of the response of the ocean basins and shallow continental shelves to the increased ocean volumes following ice melt including a process known as ocean siphoning i e glacio hydro isostatic adjustment processes several seminal studies in the early 1980s produced important data sets from the australasian region that have provided a solid foundation for more recent palaeo sea level research this review revisits these key studies emphasising their continuing influence on quaternary research and incorporates relatively recent investigations to interpret the nature of post glacial sea level change around australia these include a synthesis of research from the northern territory queensland new south wales south australia and western australia a focus of these more recent studies has been the re examination of 1 the accuracy and reliability of different proxy sea level indicators 2 the rate and nature of post glacial sea level rise 3 the evidence for timing elevation and duration of mid holocene highstands and 4 the notion of mid to late holocene sea level oscillations and their basis based on this synthesis of previous research it is clear that estimates of past sea surface elevation are a function of eustatic factors as well as morphodynamics of individual sites the wide variety of proxy sea level indicators used their wide geographical range and their indicative meaning some progress has been made in understanding the variability of the accuracy of proxy indicators in relation to their contemporary sea level the inter comparison of the variety of dating techniques used and the nuances of calibration of radiocarbon ages to sidereal years these issues need to be thoroughly understood before proxy sea level indicators can be incorporated into credible reconstructions of relative sea level change at individual locations many of the issues which challenged sea level researchers in the latter part of the twentieth century remain contentious today divergent opinions remain about 1 exactly when sea level attained present levels following the most recent post glacial marine transgression pmt 2 the elevation that sea level reached during the holocene sea level highstand 3 whether sea level fell smoothly from a metre or more above its present level following the pmt 4 whether sea level remained at these highstand levels for a considerable period before falling to its present position or 5 whether it underwent a series of moderate oscillations during the holocene highstand

earthquake prediction in seismogenic areas of the iberian peninsula based on computational intelligence abstract a method to predict earthquakes in two of the seismogenic areas of the iberian peninsula based on artificial neural networks anns is presented in this paper anns have been widely used in many fields but only very few and very recent studies have been conducted on earthquake prediction two kinds of predictions are provided in this study a the probability of an earthquake of magnitude equal or larger than a preset threshold magnitude within the next 7 days to happen b the probability of an earthquake of a limited magnitude interval to happen during the next 7 days first the physical fundamentals related to earthquake occurrence are explained second the mathematical model underlying anns is explained and the configuration chosen is justified then the anns have been trained in both areas the alboran sea and the western azores gibraltar fault later the anns have been tested in both areas for a period of time immediately subsequent to the training period statistical tests are provided showing meaningful results finally anns were compared to other well known classifiers showing quantitatively and qualitatively better results the authors expect that the results obtained will encourage researchers to conduct further research on this topic

global seismicity of 2003 centroid moment tensor solutions for 1087 earthquakes abstract centroid moment tensor cmt solutions are presented for 1087 earthquakes that occurred during 2003 the solutions are obtained using the method of dziewonski et al dziewonski a m chou t a woodward j h 1981 determination of earthquake source parameters from waveform data for studies of global and regional seismicity j geophys res 86 2825 2852 and applying corrections for aspherical earth structure as represented by the whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward dziewonski a m woodward r l 1992 acoustic imaging at the planetary scale in emert h harjes h p eds acoustical imaging vol 19 plenum press new york pp 785 797 the model of inelastic attenuation of durek and ekstrom durek j j ekstrom g 1996 a radial model of inelasticity consistent with long period surface wave attenuation bull seism soc am 86 144 158 is used to predict the decay of the waveforms the focal mechanisms of the largest or otherwise significant earthquakes of 2003 are reviewed

long term earthquake clustering summary we analyse statistically the long term properties of several instrumental earthquake catalogues complete catalogues exhibit both short and long term clustering for earthquakes of all depth ranges after accounting for the effect of short term clustering we find that in residual declustered catalogues long term clustering not periodicity characterizes the occurrence of all earthquakes shallow intermediate and deep the degree of clustering in residual catalogues is the same for earthquakes in different depth ranges circumstantial evidence indicates that the long term v ariation of seismicity is governed by a power law temporal distribution as in short term clustering it is scale invariant the fractal dimension of an earthquake set on the time axis is of the order of 0 8 0 9 therefore mainshock occurrence is closer to a stationary poisson process than standard aftershock sequences of shallow earthquakes

testing earthquake prediction algorithms statistically significant advance prediction of the largest earthquakes in the circum pacific 1992 1997 abstract algorithms m8 and msc i e the mendocino scenario were used in a real time intermediate term research prediction of the strongest earthquakes in the circum pacific seismic belt predictions are made by m8 first then the areas of alarm are reduced by msc at the cost that some earthquakes are missed in the second approximation of prediction in 1992 1997 five earthquakes of magnitude 8 and above occurred in the test area all of them were predicted by m8 and msc identified correctly the locations of four of them the space time volume of the alarms is 36 and 18 correspondingly when estimated with a normalized product measure of empirical distribution of epicenters and uniform time the statistical significance of the achieved results is beyond 99 both for m8 and msc for magnitude 7 5 10 out of 19 earthquakes were predicted by m8 in 40 and five were predicted by m8 msc in 13 of the total volume considered this implies a significance level of 81 for m8 and 92 for m8 msc the lower significance levels might result from a global change in seismic regime in 1993 1996 when the rate of the largest events has doubled and all of them become exclusively normal or reversed faults the predictions are fully reproducible the algorithms m8 and msc in complete formal definitions were published before we started our experiment keilis borok v i kossobokov v g 1990 premonitory activation of seismic flow algorithm m8 phys earth and planet inter 61 73 83 kossobokov v g keilis borok v i smith s w 1990 localization of intermediate term earthquake prediction j geophys res 95 19763 19772 healy j h kossobokov v g dewey j w 1992 a test to evaluate the earthquake prediction algorithm m8 u s geol surv ofr 92 401 m8 is available from the iaspei software library healy j h keilis borok v i lee w h k eds 1997 algorithms for earthquake statistics and prediction vol 6 iaspei software library

seismicity based earthquake forecasting techniques ten years of progress abstract earthquake fault systems interact over a broad spectrum of spatial and temporal scales and in recent years studies of the regional seismicity in a variety of regions have produced a number of new techniques for seismicity based earthquake forecasting while a wide variety of physical assumptions and statistical approaches are incorporated into the various methodologies they all endeavor to accurately replicate the statistics and properties of both the historic and instrumental seismic records as a result the last ten years have seen significant progress in the field of intermediate and short term seismicity based earthquake forecasting these include general agreement on the need for prospective testing and successful attempts to standardize both evaluation methods and the appropriate null hypotheses here we differentiate the predominant approaches into models based upon techniques for identifying particular physical processes and those that filter or smooth the seismicity comparison of the methods suggests that while smoothed seismicity models provide improved forecast capability over longer time periods higher probability gain over shorter time periods is achieved with methods that integrate statistical techniques with our knowledge of the physical process such as the epidemic type aftershock sequence etas model or those related to changes in the b value for example in general while both classes of seismicity based forecasts are limited by the relatively short time period available for the instrumental catalog significant advances have been made in our understanding of both the limitations and potential of seismicity based earthquake forecasting there is general agreement that both short term forecasting on the order of days to weeks and longer term forecasting over five to ten year periods is within reach this recent progress serves to illuminate both the critical nature of the different temporal scales intrinsic to the earthquake process and the importance of high quality seismic data for the accurate quantification of time dependent earthquake hazard

long term probabilistic forecasting of earthquakes we estimate long term worldwide earthquake probabilities by extrapolating catalogs of seismic moment solutions we base the forecast on correlations of seismic moment tensor solutions the forecast is expressed as a map showing predicted rate densities for earthquake occurrence and for focal mechanism orientation focal mechanisms are used first to smooth seismicity maps to obtain expected hazard maps and then to forecast mechanisms for future earthquakes several types of smoothing kernels are used in space domain we use the 1 distance kernel for the distribution of seismicity around any epicenter the kernel is parameterized using two adjustable parameters maximum distance and directivity distribution of seismicity around an epicenter with regard to the focal mechanism of an earthquake for temporal prediction we use the poisson hypothesis of earthquake temporal behavior we test these forecasts we use the first half of a catalog to smooth seismicity level and the second half of the catalog is used to validate and optimize the prediction to illustrate the technique we use available data in the harvard catalog of seismic moment solutions to evaluate seismicity maps for several seismic regions the method can be used with similar catalogs the technique is completely formal and does not require human operator intervention hence the prediction results can be objectively tested moreover the maps can be used as the poisson null hypothesis for testing by the likelihood method against any other prediction model which shares the same sample space the same zones time window and acceptance criteria

variability of surface ocean radiocarbon and stable isotopes in the southwestern pacific we present high precision radiocarbon 14c results and stable isotope 18o and 13c records for a coral from heron island 23 s 152 e and new stable isotope 18o and 13c records for annual coral bands from abraham reef 22 s 153 e in the southern great barrier reef studied earlier druffel and griffin 1993 these tracers provide unique information on the regional water mass history and together these data allow us to constrain the variability of circulation in the upper pacific over the past four centuries first we observe decreases in 18o of coral from abraham reef and heron island indicating an increase in sea surface temperature and or a decrease in surface salinity since 1850 second the small suess effect value 14c decrease from 1880 to 1955 due mostly to fossil fuel co2 observed previously at abraham reef druffel and griffin 1993 is confirmed in the measurements reported here from the heron island coral this value is low compared to those observed in other areas of the ocean druffel 1997 druffel and linick 1978 nozaki et al 1978 between 1880 and 1955 third we report alterations in the correlation between el nino events and the occurrence of low 14c which is indicative of long term change s in circulation in the sw pacific the 14c shifts reported here are not large but even small temporal changes in prebomb 14c suggest that important changes in the large scale state of the ocean have occurred such as a temporal change in circulation

mesoscale structure of the mean east australian current system and its relationship with topography abstract we document the mean circulation of the east australian current eac system which is the major western boundary current in the southwest pacific ocean a new high resolution climatology of the region csiro atlas of regional seas cars is used to produce regional fields of steric height and sections of geostrophic velocity the realism of these fields has been enhanced by the high spatial resolution allowance for bathymetric control and the influence of land barriers the increased detail in the maps and sections reveal the major influence that the complex regional topography has on the circulation the results also provide the appropriate resolution for comparison with recent model studies of the region we have been able to both resolve well known features with greater detail and identify previously unrecognized aspects of the circulation important results include 1 the zonal inflow north of 30 s breaks into a series of individual jets after flowing through the island chains as suggested by recent model results 2 the interaction of the zonal inflow with the local topography as it undergoes bifurcation is documented 3 a detailed picture of the evolution of the eac at the western boundary is presented including surface currents and transports 4 separation and recirculation of the eac within the tasman abyssal basin are shown to occur as a double cell structure constrained by bathymetry 5 the eac outflow is resolved as a series of eastward and northeastward currents 6 the path of the tasman front is defined as it interacts with the tasman ridge systems 7 a quasi permanent eddy is identified for the first time adjacent to the norfolk ridge northwest of new zealand

a large drop in atmospheric 14c 12c and reduced melting in the younger dryas documented with 230th ages of corals paired carbon 14 14 c and thorium 230 230 th ages were determined on fossil corals from the huon peninsula papua new guinea the ages were used to calibrate part of the 14 c time scale and to estimate rates of sea level rise during the last deglaciation an abrupt offset between the 14 c and 230 th ages suggests that the atmospheric 14 c 12 c ratio dropped by 15 percent during the latter part of and after the younger dryas yd this prominent drop coincides with greatly reduced rates of sea level rise reduction of melting because of cooler conditions during the yd may have caused an increase in the rate of ocean ventilation which caused the atmospheric 14 c 12 c ratio to fall the record of sea level rise also shows that globally averaged rates of melting were relatively high at the beginning of the yd thus these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the mississippi to the st lawrence river triggered the yd event

speleothem derived asian summer monsoon variations in central china 54 46 ka the oxygen isotope signature delta o 18 of stalagmite si3 collected from shizi cave in north east sichuan province provides an asian summer monsoon asm record in central china for the period 54 46 ka the si3 delta o 18 record clearly shows a negative delta o 18 excursion centred around 49 4 ka which was reported in hulu cave in east china but not identified in the speleothem records from south west china as a whole this record displays a higher coherence with the two hulu records from east china than with the speleothem delta o 18 records from south west china suggesting that at 54 46 ka central china was influenced more by the east asian summer monsoon than by the indian summer monsoon it also displays a significant negative delta o 18 excursion at 47 5 46 6 ka which is not clearly documented in two other speleothem delta o 18 records previously reported from south west china this suggests that details of the greenland interstadial 12 warrant further investigations in future in monsoonal china the si3 delta o 18 record displays more significant centennial scale variations than the other four speleothem delta o 18 records from east and south west china which may be due to the fact that the study site is closer to the north west boundary of the asm and more sensitive to variations of the asm than east and south west china copyright c 2011 john wiley sons ltd

kuroshio intrusion into the south china sea a review the kuroshio carrying the northwestern pacific water intrudes into the south china sea scs through the luzon strait significantly affecting the temperature salinity circulation and eddy generation in the scs thus the kuroshio intrusion makes important contributions to the momentum heat and salt budgets in the scs in the past decades much work has been done on the kuroshio intrusion this paper reviews past efforts and summarizes our current understanding of the kuroshio intruding processes from observational evidence laboratory results theoretical analyses and a range of numerical model simulations in addition discrepancies between results simulated by models as well as those between simulations and observations are presented specifically this paper addresses the following topics 1 different types of the kuroshio intrusion into the scs and their identification 2 vertical structure of the kuroshio in the luzon strait 3 an overview of the luzon strait transport resulting from observations and numerical model simulations 4 seasonal and interannual variations of the kuroshio intrusion as well as eddy generation due to the kuroshio path variation and 5 dynamical mechanisms e g wind forcing interbasin pressure gradient beta effect and hysteresis potential vorticity eddy activity controlling the kuroshio intrusion into the scs finally several future research topics for gaining a better understanding of the kuroshio intruding processes are suggested c 2014 the authors published by elsevier ltd

temporal variability in the holocene marine radiocarbon reservoir effect for the tropical and south pacific understanding the marine radiocarbon reservoir effect i e marine radiocarbon reservoir age r and or correction r is important for the construction of robust radiocarbon chronologies for marine archives for various research areas including archaeology palaeoecology paleoceanography quaternary research and climate change studies in this study we examined temporal r variability for the south china sea scs and the great barrier reef gbr during the past 8 1 ka based on 14c analysis of 230th dated corals results show large r variations of 410 yr and 490 yr for the scs and the northern gbr for 5 5 8 1 ka and 5 5 7 ka respectively and a smaller r variability of 200 yr for the scs for 2 3 5 ka our data together with those previously published for the tropical and south pacific indicate that variability in ocean upwelling bringing old subsurface waters to the surface and or changes in the sources or 14c level of the upwelled waters are responsible for seeing large r variations in coastal areas along the eastern pacific and the tropical east pacific tep of several hundred to a thousand years mostly during the early to middle holocene r variations in the central and western pacific of several and a couple of hundred years during the middle and late holocene respectively might be due to variability in pacific wide ocean circulation associated with climatic changes controlling the spread of upwelled waters from the tep to the west this mechanism together with local regional effects such as changes in ocean upwelling in the scs resulting from east asian monsoon variability and changes in upwelling and or horizontal advection in the northern gbr associated with variability in the el nino southern oscillation might be responsible for the observed r variations in these areas the results of our study also indicate the need for regional marine radiocarbon calibration curves for improved radiocarbon dating of marine samples as the observed holocene r values for the tropical and south pacific are not fully reproduced by a recent modelling work using a 3d ocean model which takes into account climate change effects ocean circulation changes were included in the model for the period of 11 5 50 cal kyr bp but possibly not considered or not well represented for the holocene which might explain the differences between the observed and modelled r values

foreshock occurrence rates before large earthquakes worldwide global rates of foreshock occurrence involving shallow m 6 and m 7 mainshocks and m 5 foreshocks were measured using earthquakes listed in the harvard cmt catalog for the period 1978 1996 these rates are similar to rates ones measured in previous worldwide and regional studies when they are normalized for the ranges of magnitude difference they each span the observed worldwide rates were compared to a generic model of earthquake clustering which is based on patterns of small and moderate aftershocks in california and were found to exceed the california model by a factor of approximately 2 significant differences in foreshock rate were found among subsets of earthquakes defined by their focal mechanism and tectonic region with the rate before thrust events higher and the rate before strike slip events lower than the worldwide average among the thrust events a large majority composed of events located in shallow subduction zones registered a high foreshock rate while a minority located in continental thrust belts measured a low rate these differences may explain why previous surveys have revealed low foreshock rates among thrust events in california especially southern california while the worldwide observations suggest the opposite california lacking an active subduction zone in most of its territory and including a region of mountain building thrusts in the south reflects the low rate apparently typical for continental thrusts while the worldwide observations dominated by shallow subduction zone events are foreshock rich

comment on testing earthquake prediction methods the west pacific short term forecast of earthquakes with magnitude mwhrv 5 8 by v g kossobokov in his paper kossobokov investigates the efficiency of our short term forecast for two western pacific regions although we agree with the basic results of his evaluation that the forecast statistics is much better than a random guess we have reservations about his definition of earthquake prediction some of his tests and his interpretation of the test results we distinguish between deterministic earthquake predictions and statistical forecasts we argue that some techniques used by kossobokov may not be appropriate for testing our forecasts and discuss other testing methods based on the likelihood function we demonstrate that kossobokov s null hypothesis may be biased and this bias can influence some of his conclusions we show that contrary to kossobokov s statement our algorithm predicts mainshocks when they are preceded by foreshocks

interevent times in a new alarm based earthquake forecasting model summary this study introduces a new earthquake forecasting model that uses the moment ratio mr of thefirst to second order moments of earthquake interevent times as a precursory alarm index to forecast large earthquake events this mr model is based on the idea that the mr is associated with anomalous long term changes in background seismicity prior to large earthquake events in a given region the mr statistic is defined as the inverse of the index of dispersion or fano factor with mr values or scores providing a biased estimate of the relative regional frequency of background events here termed the background fraction to test the forecasting performanceofthisproposedmrmodel acompositejapan wideearthquakecatalogueforthe years between 679 and 2012 was compiled using the japan meteorological agency catalogue for the period between 1923 and 2012 and the utsu historical seismicity records between 679 and 1922 mr values were estimated by sampling interevent times from events with magnitude m 6 using an earthquake random sampling ers algorithm developed during previous research three retrospective tests of m 7 target earthquakes were undertaken to evaluate the long intermediate and short term performance of mr forecasting using mainly molchan diagrams and optimal spatial maps obtained by minimizing forecasting error defined by miss and alarm rate addition this testing indicates that the mr forecasting technique performs well at long intermediate and short term the mr maps produced during longterm testing indicate significant alarm levels before 15 of the 18 shallow earthquakes within the testing region during the past two decades with an alarm region covering about 20percent alarm rate of the testing region the number of shallow events missed by forecasting was reduced by about 60percent after using the mr method instead of the relative intensity ri forecasting method at short term our model succeeded in forecasting the occurrence region of the 2011 mw 9 0 tohoku earthquake whereas the ri method did not cases where a period of quiescent seismicity occurred before the target event often lead to low mr scores meaning that the target event was not predicted and indicating that our model could be further improved by taking into account quiescent periods in the alarm strategy

a high resolution absolute dated holocene and deglacial asian monsoon record from dongge cave china abstract we present a continuous record of the asian monsoon over the last 16 ka from 18o measurements of stalagmite calcite over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230th dates 18o and therefore asian monsoon intensity generally follows changes in insolation although changes in 18o are generally accommodated in abrupt shifts in contrast to smoothly varying insolation indicating that threshold effects may be important 18o decreased dramatically 3 at the start of the holocene 11 5 ka and remained low for 6 ka four positive 18o events centered at 11225 97 yr bp 1 05 10880 117 yr bp 1 15 9165 75 yr bp 1 4 and a double event centered at 8260 64 yr bp 1 1 and 8080 74 yr bp 1 0 punctuated this period of high monsoon intensity all four events correlate within error with climate changes in greenland ice cores thus the relationship between the asian monsoon and the north atlantic observed during the glacial period appears to continue into the early holocene in addition three of the four events correlate within error with outburst events from lake agassiz the decline of monsoon intensity in the mid late holocene is characterized by an abrupt positive shift in 18o which occurs at 3550 59 yr bp 1 1 in 100 yr in addition the holocene is punctuated by numerous centennial and multi decadal scale events amplitudes 0 5 to 1 up to half the amplitude of the glacial interstadial events seen in the last glacial period thus holocene centennial and multi decadal scale monsoon variability is significant although not as large as glacial millennial scale variability the monsoon shows a strong connection with northern south american hydrological changes related by changes in itcz position spectral analysis of the 18o record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing however there are numerous other significant peaks including peaks at el nino frequencies observed for high resolution portions of the record between 8110 and 8250 yr which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling holocene monsoon climate in addition for this high resolution portion we observe a distinctive biennial oscillation of the asian monsoon which has been associated with the tropospheric biennial oscillation tbo

wintertime circulation off southeast australia strong forcing by the east australian current numerical results and observations are used to examine the sub weather band wintertime circulation off the eastern shelf slope region between tasmania and cape howe the numerical model is forced using wintertime averaged atmospheric fluxes of momentum heat and freshwater and using transports along open boundaries that are obtained from a global ocean model the boundary to the north of cape howe has a prescribed transport of 17 sv which from available observations represents strong forcing by the east australian current eac nonetheless the model results are in qualitative and quantitative agreement with several observational studies in accord with observations water within bass strait is found to be driven to the east and north with speeds of up to 30 cm s 1 off the southeast victorian coast the water is colder and denser than that found farther offshore which is associated with the southward flowing warm eac in agreement with observations the density difference between the two water masses is about 0 6 kg m 3 and leads to a cascade of dense bass strait water to depths of 300 m and as a plume that extends 5 10 km in the cross shelf direction typical vertical velocities of the model cascade are 20 m d 1 along isobath currents become bottom intensified with speeds of 20 cm s 1 or so at depths of 200 m the eac is found to flow along isobaths and to the south and then west past tasmania with speeds of up to 20 cm s 1 mesoscale eddies grow to diameters of 100 km speeds 40 cm s 1 and in accord with observations a semipermanent anticyclonic eddy is found to the east of cape howe

large variations in the holocene marine radiocarbon reservoir effect reflect ocean circulation and climatic changes accurate radiocarbon dating of marine samples requires knowledge of the marine radiocarbon reservoir effect this effect for a particular site region is generally assumed constant through time when calibrating marine 14c ages however recent studies have shown large temporal variations of several hundred to a couple of thousand years in this effect for a number of regions during the late quaternary and holocene here we report marine radiocarbon reservoir correction r r for heron reef and moreton bay in southwestern sw pacific for the last 8 ka derived from 14c analysis of 230th dated corals most of our r r for the last 5 4 ka agree well with their modern value but large r r variability of 410 yr from trough to peak with possible decadal centennial fluctuations is evident for the period 5 4 8 ka the latter time interval also has significant variations with similar features in previously published r r values for other sites in the pacific including southern peru northern chile in southeastern se pacific the south china sea vanuatu and papua new guinea with the largest magnitude of 920 yr from se pacific the mechanisms for these large r r variations across the pacific during the mid holocene are complex processes involving 1 changes in the quantity and 14c content of upwelled waters in tropical east pacific tep frequency and intensity of ocean upwelling in the tep and contribution of subantarctic mode water to the upwelled waters which is influenced by the intensity and position of southern westerly winds and 2 variations in ocean circulation associated with climate change la nina el nino conditions intensity of easterly trade winds positions of the intertropical convergence zone and the south pacific convergence zone which control the spreading of the older upwelled surface waters in the tep to the western sites our results imply the need for employing temporal changes in r r values instead of constant modern values for age calibration of holocene marine samples not only for the sw pacific sites but also for other tropical and subtropical sites in the pacific

comparison of short term and time independent earthquake forecast models for southern california we have initially developed a time independent forecast for southern california by smoothing the locations of magnitude 2 and larger earthquakes we show that using small m 2 earthquakes gives a reasonably good prediction of m 5 earthquakes our forecast outperforms other time independent models kagan and jackson 1994 frankel et al 1997 mostly because it has higher spatial resolution we have then developed a method to estimate daily earthquake probabilities in south ern california by using the epidemic type earthquake sequence model kagan and knopoff 1987 ogata 1988 kagan and jackson 2000 the forecasted seismicity rate is the sum of a constant background seismicity proportional to our time independent model and of the aftershocks of all past earthquakes each earthquake triggers aftershocks with a rate that increases exponentially with its magnitude and decreases with time following omori s law we use an isotropic kernel to model the spatial distribution of aftershocks for small m 5 5 mainshocks for larger events we smooth the density of early aftershocks to model the density of future aftershocks the model also assumes that all earthquake magnitudes follow the gutenberg richter law with a uniform b value we use a maximum likelihood method to estimate the model parameters and test the short term and time independent forecasts a retro spective test using a daily update of the forecasts between 1 january 1985 and 10 march 2004 shows that the short term model increases the average probability of an earthquake occurrence by a factor 11 5 compared with the time independent forecast

a worldwide test of three long term premonitory seismicity patterns a review abstract worldwide analysis of the clustering of earthquakes has lead to the hypothesis that the occurrence of abnormally large clusters indicates an increase in probability of a strong earthquake in the next 3 4 years within the same region three long term premonitory seismicity patterns which correspond to different non contradictory definitions of abnormally large clusters were tested retrospectively in 15 regions the results of the tests suggest that about 80 of the strongest earthquakes can be predicted by monitoring these patterns most of results concern pattern b burst of aftershocks i e an earthquake of medium magnitude with an abnormally large number of aftershocks during the first few days two other patterns s and often complement pattern b and can replace it in some regions where the catalogs show very few aftershocks the practical application of these patterns is strongly limited by the fact that neither the location of the coming earthquake within the region nor its time of occurrence within 3 4 years is indicated however these patterns present the possibility of increasing the reliability of medium and short term precursors also they allow activation of some important early preparatory measures the results impose the following empirical constraint on the theory of the generation of a strong earthquake it is preceded by abnormal clustering of weaker earthquakes in the space time energy domain corresponding clusters are few but may occur in a wide region around the location of the coming strong earthquake the distances are of the same order as for the other reported precursors

holocene marine 14c reservoir age variability evidence from 230th dated corals in the south china sea the south china sea scs is well connected with the western pacific and influenced by the east asian monsoon we have examined temporal variations in radiocarbon marine reservoir ages r and regional marine reservoir corrections delta r of the scs during the holocene using paired measurements of ams c 14 and tims th 230 on 20 pristine corals the results show large fluctuations in both r and delta r values over the past 7500 years yrs with two distinct plateaus during 7 5 5 6 and 3 5 2 5 thousand calendar years before present cal ka bp the respective weighted mean delta r values of these plateaus are 151 85 and 89 59 yrs which are significantly higher than its modern value of 23 52 yrs this suggests that using a constant modern delta r value to calibrate c 14 dates of the scs marine samples will introduce additional errors to the calibrated ages our results provide the first database for the holocene r and delta r values of the scs for improved radiocarbon calibration of marine samples we interpret the two delta r plateaus as being related to two intervals with weakened el nino southern oscillation enso and intensified east asian summer monsoon easm this is because the c 14 content of the scs surface water is controlled by both the c 14 concentration of the pacific north equatorial current nec which is in turn influenced by enso induced upwelling along the pacific equator and vertical upwelling within the scs as a result of moisture transportation to midlatitude region to supply the easm rainfall

on the surface circulation in the western coral sea and residence times in the great barrier reef surface velocity observations from satellite tracked drifters made between 1987 and 2008 were used to resolve the surface circulation of the western coral sea west of 158 e and the great barrier reef gbr the mean surface current map depicts well the major circulation patterns of the region such as the position of the north vanuatu and north caledonia jets nvj and ncj and the western boundary currents the north queensland current nqc and the east australian current eac are well defined flowing at speeds greater than 50 cm s 1 to the north south of 15 s and 19 s respectively the nqc eac is mainly formed by the nvj ncj flows respectively the presence of the queensland plateau greatly affects the westward flow causing a zone of weak and highly variable currents that extends from 15 s to 18 s between the queensland plateau and the gbr shelf of the 235 drifters that crossed the western coral sea 75 entered the gbr analysis of the drifter trajectories inside the gbr reveals the presence of a northwestward circulation at speeds of 22 cm s 1 north of 18 s and 0 5 cm s 1 south of 18 s drifter travel times used to evaluate the water residence times within the gbr indicate residence times of a few weeks for most of the lagoon

glacial interglacial changes in the east australian current the east australian current eac is the western boundary current of the south pacific gyre transporting warm tropical waters to higher southern latitudes recent modelling shows that the partial separation of the eac 32 s and the coupled formation of the tasman front 34 s are caused by a steep gradient in the zonally integrated wind stress curl analysis of oxygen isotope ratios 18o in the planktonic foraminifer globigerinoides ruber from sediment cores from the coral sea and tasman sea indicates that the eac separation shifted northward to between 23 and 26 s during the last glacial we suggest these results indicate a significant change in the pacific wind stress curl during the glacial given recent evidence for el nino like conditions in the pacific during the last glacial with a reduction in the east west sea surface temperature sst gradient we suggest that weaker trade winds combined with more northerly stronger westerlies were associated with a change to the wind stress curl which repositioned the eac separation and tasman front in contrast by 11 ka bp the eac separation was forced south of 26 s this southward shift was synchronous with a rapid warming of tropical ssts and the onset of a la nina like sst configuration across the tropical pacific it appears that the south pacific trade winds strengthened accordingly causing the eac to readjust its flow this readjustment of the eac marks the onset of modern surface ocean circulation in the southwest pacific but the present eac transport was only achieved in the late holocene after 5 ka bp

marine radiocarbon reservoir effect along the northern chile southern peru coast 14 24 s throughout the holocene abstract through an extensive sampling and dating of pairs of associated shells and charcoal fragments combined with reanalysis of all the available previous data we reconstruct the evolution throughout the holocene of the regional marine radiocarbon reservoir effect r values along the northern chile southern peru area 14 24 s after elimination of the cases in which the terrestrial component yielded older ages than the marine shells to which they were associated the study is based upon data from 47 pairs of associated marine and terrestrial material our results suggest major changes in both the magnitude and variability range of r during the whole holocene period 1 between 10 400 and 6840 cal yr bp high values 511 278 yr probably result from a strengthened se pacific subtropical anticyclone and shoaling of equatorial subsurface waters during intensified upwelling events 2 between 5180 and 1160 cal yr bp lower values 226 98 yr may reflect a major influence of subtropical water and diminished coastal upwelling processes 3 during the last thousand years high values between 355 105 and 253 207 yr indicate an increased influence of 14 c depleted water masses and of enso for the early twentieth century a r value of 253 207 yr was calculated

226ra in barite absolute dating of holocene southern ocean sediments and reconstruction of sea surface reservoir ages absolute dating of marine sediments is necessary to achieve reliable correlations of paleoclimate records the 2 2 6 ra decay in barite separated from a deep sea core of the southern ocean was used to determine absolute ages for the holocene epoch comparison with 1 4 c ages measured on planktic foraminifers provides the first past sea surface reservoir ages in the antarctic zone of the southern ocean throughout the middle to late holocene our results indicate a reservoir age of ca 1100 yr comparable to modern estimates a significantly higher reservoir age ca 1900 yr is obtained for the early holocene which suggests a major change in the southern ocean circulation at that time