correlations of earthquake focal mechanisms summary we performed a statistical analysis of the harvard catalogue of seismic moment tensor solutions we investigated the distribution of hypocentres on focal spheres of earthquakes the hypocentres are concentrated along fault planes the hypocentre distribution does not significantly differ for earthquakes in different depth ranges to study the rotation of focal mechanisms we have solved an inverse problem of a 3 d rotation of double couple earthquake sources i e for each pair of focal mechanisms we find all four 3 d rotations which rotate one mechanism into another the stochastic disorientation of focal mechanisms is well approximated by the rotational cauchy distribution which has previously been identified through theoretical arguments and simulations as the result of stress perturbations caused by random defects in the medium the cauchy distribution is characterized by one parameter k k 0 means no rotations and k 0 5 corresponds to approximately random rotation for earthquake focal mechanisms the value of k is between 0 05 and 0 1 in a fault zone and it increases with distance between pairs of events in directions other than a fault plane k reaches the value 0 5 the cauchy distribution is then close to completely random rotations although k increases slowly with depth in general disorientations of focal mechanisms in various depth ranges display the same dependence therefore we can conclude that deep earthquakes are controlled by the same stress interaction regime as shallow events the results of these measurements made us question the suitability of some terms and models that are commonly used in the theory of an earthquake source for example we argued that tectonic earthquakes rupture rock material which has large scale defects or faults comparable in size with tectonic blocks in which they originate properties of the rocks should be significantly different from those of regular materials where the size of defects is typically much smaller than the scale of interest these properties should strongly depend on the geometry location and orientation of major defects

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

seismic gaps and earthquakes 1 mccann et al 1979 published a widely cited seismic gap model ascribing earthquake potential categories to 125 zones surrounding the pacific rim nishenko 1991 published an updated and revised version including probability estimates of characteristic earthquakes with specified magnitudes within each zone these forecasts are now more than 20 and 10 years old respectively and sufficient data now exist to test them rather conclusively for the mccann et al forecast we count the number of qualifying earthquakes in the several categories of zones we assume a hypothetical probability consistent with the gap model e g red zones have twice the probability of green zones and test against the null hypothesis that all zones have equal probability the gap hypothesis can be rejected at a high confidence level contrary to the forecast of mccann et al the data suggest that the real seismic potential is lower in the gaps than in other segments and plate boundary zones are not made safer by recent earthquakes for the 1991 nishenko hypothesis we test the number of filled zones the likelihood scores of the observed and simulated catalogs and the likelihood ratio of the gap hypothesis to a poissonian null hypothesis for earthquakes equal to or larger than the characteristic magnitude the new seismic gap hypothesis failed at the 95 confidence level in both the number and ratio tests if we lower the magnitude threshold by 0 5 for qualifying earthquakes the new gap hypothesis passes the number test but fails in both the likelihood and likelihood ratio tests at the 95 confidence level

linear and nonlinear relations between relative plate velocity and seismicity relationships between relative plate velocity and seismicity differ by plate boundary class we test the null hypothesis of linearity of earthquake rates with velocity in each of seven classes a linear relationship is expected if earthquake rate is proportional toseismicmoment rate whichis proportional torelative platevelocity to reducebiasbyaftershocksandswarms weestimateindependenceprobabilitiesofearth quakes and use them as weights we assign shallow earthquakes to boundary steps and classes thensortboundarystepswithineachclassbyvelocityandplotcumulativeearth quakesagainstcumulativemodelmomentrate weusetwomeasuresofnonlinearityand 10 4 stochastic simulations to assess significance in subduction zones the relationship betweenseismicityandvelocityisnonlinearwith99 9 confidence slowersubduction at 66 mm a producing35 oftectonicmomentunderthenullhypothesis produces only 20 of subduction earthquakes continental convergent boundaries display simi larnonlinearity p 0 001forthenullhypothesis oceanspreadingridgesshowseis micity decreasing with velocity oceanic transform faults and oceanic convergent boundaries show marginal nonlinearity p 0 01 p 0 05 continental rifts and continental transform faults follow the null hypothesis three effects may contribute to velocity dependence in subduction 1 the brittle ductile transition at a critical tem peratureisadvecteddeeperbyfasterunderthrusting 2 subductedsedimentisviscous so lower stresses in slower boundaries discourage earthquakes 3 pore pressures increase with velocity encouraging frictional failure mechanism 1 has only minor effects on earthquake productivity but mechanisms 2 and 3 could be important online material earthquake subcatalogs and cumulative distribution tables

seismic moment catalog of large shallow earthquakes 1900 to 1989 we compile a worldwide catalog of shallow depth 70 km and large ms 7 earthquakes recorded between 1900 and 1989 the catalog is shown to be complete and uniform at the 20 sec surface wave magnitude ms 7 0 we base our catalog on those of abe 1981 1984 and abe and noguchi 1983a b for events with ms 7 0 those catalogs however are not homogeneous in seismicity rates for the entire 90 year period we assume that global rates of seismicity are constant on a time scale of decades and most inhomogeneities arise from changes in instrumentation and or reporting we correct the magnitudes to produce a homogeneous catalog the catalog is accompanied by a reference list for all the events with seismic moment determined at periods longer than 20 sec using these seismic moments for great and giant earthquakes and a moment magnitude relationship for smaller events we produce a seismic moment catalog for large earthquakes from 1900 to 1989 the catalog is used to study the distribution of moment released worldwide although we assumed a constant rate of seismicity on a global basis the rate of moment release has not been constant for the 90 year period because the latter is dominated by the few largest earthquakes we find that the seismic moment released at subduction zones during this century constitutes 90 of all the moment released by large shallow earthquakes on a global basis the seismic moment released in the largest event that occurred during this century the 1960 southern chile earthquake represents about 30 to 45 of the total moment released from 1900 through 1989 a frequency size distribution of earthquakes with seismic moment yields an average slope b value that changes from 1 04 for magnitudes between 7 0 and 7 5 to b 1 51 for magnitudes between 7 6 and 8 0 this change in the b value is attributed to different scaling relationships between bounded large and unbounded small earthquakes thus the earthquake process does have a characteristic length scale that is set by the downdip width over which rupture in earthquakes can occur that width is typically greater for thrust events at subduction zones than for earthquakes along transform faults and other tectonic environments

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

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

seismic moment distribution summary we review possible errors in determining the size of earthquakes we propose that the size distribution can be effectively defined only for earthquake sequences not for individual earthquakes as a result of the error analysis we question the validity of many reported correlations between the 6 value and spatio temporal characteristics of tectonics and seismicity the study of the distribution of earthquake seismic moment largely avoids the influence of these errors and biases and is therefore superior to the standard analysis of the magnitude frequency law the gamma distribution is applied to describe the distribution of seismic moments of earthquake sequences this distribution which generalizes the well known gutenberg richter g r relation is characterized by two parameters we use the maximum likelihood method to determine the parameters of the gamma distribution for worldwide earthquakes in different depth ranges the empirical distribution is derived from the moment tensor catalogue compiled by the harvard group the p value for scalar seismic moment of earthquake sequences an analogue of the 6 value in the g r magnitude frequency law is close to 1 2 for all earthquakes the value predicted by a critical branching model of seismicity this result which will be improved as more seismic moment data become available provides input for modelling of seismicity based on percolation or on self organized criticality models if 3 equals 1 2 then using the critical branching model we find that most small earthquakes in available catalogues are dependent shocks i e aftershocks even among earthquakes of intermediate magnitudes the number of dependent events may exceed that of independent events

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

cephalopod ancestry and ecology of the hyolith allatheca degeeri s l in the cambrian evolutionary radiation abstract pyritized elongate conical conchs of allatheca degeeri s l are common in dysoxic dark gray mudstone intervals in the early cambrian upper terreneuvian series 2 boundary interval cuslett formation at keels eastern newfoundland wave oriented horizontal specimens are most abundant in this cool water high latitude off shore shelf facies of the early palaeozoic avalon microcontinent based on conch morphology shell microstructure and the operculum the species is an orthothecid hyolith comparison with the sizes of the early shells of planktic gastropods indicates a non planktic life mode of a degeeri s l hatchlings although buoyancy calculations show that small juveniles with septate conchs to ca 17 mm long could have been nektic planktic if smaller a degeeri s l individuals had a non benthic mode of life they and pseudoconodonts were the oldest skeletalized pelagic nektic animals in the cambrian evolutionary radiation most a degeeri s l conchs at keels are horizontally embedded and show a bimodal wave determined orientation but about 10 of the large conchs are vertically embedded with their aperture down as larger shells were not neutrally buoyant the vertical orientations of about 10 of the conchs suggests an infaunal likely detritivore life mode suggestive of a scaphopod available morphologic and taphonomic evidence suggests that the vertically embedded conchs are in situ remains of dead benthic animals that colonized the bottom in better oxygenated intervals based on the current knowledge of early palaeozoic hyolith and cephalopod larval and adult morphologies existing hypotheses of a planktic origin of cephalopods from hyolith ancestors are evaluated and no evidence for such an evolutionary relationship is concluded to exist

revised tectonic forecast of global shallow seismicity based on version 2 1 of the global strain rate maprevised tectonic forecast of global shallow seismicity based on version 2 1 of the global strain rate map

are spontaneous earthquakes stationary in california 1 aftershocks and some main shocks are triggered with timing controlled by preceding events the remaining spontaneous earthquakes presumably respond to tectonic stresses we consider whether triggered events can be reliably identified whether the rest are stationary and whether external phenomena control them to all three questions some studies of earthquake physics and hazard assume answers many suggest that stress changes from large distant earthquakes can alter the local spontaneous earthquake rate we demonstrate significant differences in the apparent earthquake rate after declustering by different methods and we present criteria for assessing the influence of such distant events the estimated spontaneous earthquake rate depends on the lower magnitude threshold of included events whether spontaneity is treated in binary or probabilistic form as well as assumptions about catalog completeness different statistical tests give different answers to the question of stationarity we examine a reported rate change in southern california and the suggestion that it might have resulted from the 1960 chile and 1964 alaska earthquakes the rate change itself is questionable if it has occurred it was probably not caused by those distant events because the rate change is not present in northern california or in all parts of southern california

seismicity alert probabilities at parkfield california revisited for a decade the u s geological survey has used the parkfield earthquake prediction experiment scenario document to estimate the probability that earthquakes observed on the san andreas fault near parkfield will turn out to be foreshocks followed by the expected magnitude 6 mainshocks during this time we have learned much about the seismogenic process at parkfield about the long term probability of the parkfield mainshock and about the estimation of these types of probabilities the probabilities for potential foreshocks at parkfield are reexamined and revised in light of these advances as part of this process we have confirmed both the rate of foreshocks before strike slip earthquakes in the san andreas physiographic province and the uniform distribution of foreshocks with magnitude proposed by earlier studies compared to the earlier assessment these new estimates of the long term probability of the parkfield mainshock are lower our estimate of the rate of background seismicity is higher and we find that the assumption that foreshocks at parkfield occur in a unique way is not statistically significant at the 95 confidence level while the exact numbers vary depending on the assumptions that are made the new alert probabilities are lower than previously estimated considering the various assumptions and the statistical uncertainties in the input parameters we also compute a plausible range for the probabilities the range is large partly due to the extra knowledge that exists for the parkfield segment making us question the usefulness of these numbers

earthquake statistics at parkfield 2 probabilistic forecasting and testing construct two probabilistic forecasts h 1 with a spatially varying b value and h 2 with a uniform b value and test these hypotheses against each other both hypotheses use a spatially varying seismicity level a value determined from past seismicity we used a range of sampling parameters magnitude threshold cell size etc to assure robust results we found that in most of the tests hypothesis h 1 showed a higher likelihood than h 2 although both are a poor approximation to the seismicity data the most positive results for h 1 are obtained for testing magnitude ranges down to m 1 5 and with sampling radii as defined in paper 1 as appropriate for parkfield the superior performance of h 1 suggests that spatially varying b values should be considered in earthquake forecasts index terms 7215 seismology earthquake parameters 7223 seismology seismic hazard assessment and prediction 7230 seismology seismicity and seismotectonics keywords earthquake statistics probabilistic forecasting parkfield

earthquake potential of the sichuan yunnan region western china abstract we estimate the seismic hazard potential in the sichuan yunnan region western china using three different approaches our first approach based on the assumption that the earthquake probability is proportional to the past seismicity rate uses a regional earthquake catalog to constrain the probability model a retrospective test shows that the forecasts have some predictive power for strong events occurred on fault segments with shorter earthquake recurrence time but not for that with longer recurrence time such as the longmenshan fault our second approach based on the assumption that the earthquake probability is proportional to crustal strain rate uses secular geodetic strain rate deduced from gps velocity data to constrain the probability model a retrospective test of the model with earthquake occurrence of the past 30 years shows that the model forecasted poorly however the model seems to forecast spatial intensity of earthquakes for the past 500 years reasonably well suggesting that the geodetic strain rate obtained at the decadal scale may still be a good indicator of long term earthquake activity in the region but only at a time scale of hundreds of years our third approach uses gps velocity data to determine the seismic moment accumulation rates on major faults and a historical earthquake catalog to estimate seismic moments released in the past comparison of the two yields estimates of present day seismic moments cumulated on major faults and a retrospective test shows some predictive power of the method our result suggests that numerous faults in the sichuan yunnan region have cumulated seismic moments capable of producing m 7 5 earthquakes including the xiaojiang jiali northern nujiang nandinghe and red river puer faults and the junction fault between the xianshuihe and ganzi yushu faults

automated near realtime cmt inversion the earthquake research institute eri of the university of tokyo has completely automated the process of determining source mechanisms of earthquakes using waveform data the solutions are automatically distributed using the internet without being checked the process is initiated by receipt of e mail giving the origin time and location of an earthquake to determine the source mechanism we apply the harvard centroid moment tensor cmt inversion method to long period body wave data the portion of the seismogram from the first arrival to the initial surface wave the method has been successfully applied since october 1993 to all of the major earthquakes in the world for which we received event e mail 108 of the 242 cmt solutions in 1994 were determined within 6 hours of the event with an average delay of 3 8 hours for local events e g events around japan it is also possible to determine cmt solutions within 30 minutes from the occurrence of the earthquakes using an efficient dialup data retrieval system operated by eri

are earthquakes predictable summary the answer to the above question depends on the definition of earthquake prediction we discuss several definitions and possible classifications of earthquake prediction methods we also consider various measures of prediction efficiency review several recent examples of earthquake prediction and describe the methods that can be used to verify prediction schemes we conclude that an empirical search for earthquake precursors that forecast the size of an impending earthquake has been fruitless despite considerable effort in several countries no statistically rigorous validation of proposed precursory phenomena is available therefore reported cases of precursors can be explained by random noise or by chance coincidence we present evidence that earthquakes are non linear chaotic scale invariant phenomena the most probable consequence of earthquake self similarity is a lack of earthquake predictability as popularly defined that is a forecast of a specific individual earthquake many small earthquakes occur throughout any seismic zone demonstrating that the critical conditions for earthquake nucleation are satisfied almost everywhere apparently any small shock can grow into a large event thus it is likely that an earthquake has no preparatory stage this sceptical view of current earthquake prediction efforts should not be interpreted as a statement that any further attempts to mitigate the destructive effects of earthquakes are futile the seismic moment conservation principle when combined with geodetic deformation data offers a new way to evaluate the seismic hazard not only for tectonic plate boundaries but also for areas of low seismicity that is the interiors of continents earthquake clustering with a power law temporal decay omori s law can be used to estimate the rate of future earthquake ocurrence realtime seismology can facilitate relief efforts after large earthquakes and eventually provide an immediate warning of severe shaking a few seconds or tens of seconds before the shaking starts

constraints on the frequency magnitude relation and maximum magnitudes in the uk from observed seismicity and glacio isostatic recovery rates summary earthquake populations have recently been shown to have many similarities with critical point phenomena with fractal scaling of source sizes energy or seismic moment corresponding to the observed gutenberg richter g r frequency magnitude law holding at low magnitudes at high magnitudes the form of the distribution depends on the seismic moment release rate mand the maximum magnitude m max the g r law requires a sharp truncation at an absolute maximum magnitude for finite m i n contrast the gamma distribution has an exponential tail which allows a soft or credible maximum to be determined by negligible contribution to the total seismic moment release here we apply both distributions to seismic hazard in the mainland uk and its immediate continental shelf constrained by a mixture of instrumental historical and neotectonic data tectonic moment release rates for the seismogenic part of the lithosphere are calculated from a flexural plate model for glacio isostatic recovery constrained by vertical deformation rates from tide gauge and geomorphological data earthquake focal mechanisms in the uk show near vertical strike slip faulting with implied directions of maximum compressive stress approximately in the nnw sse direction consistent with the tectonic model maximum magnitudes are found to be in the range 6 3 7 5 for the g r law or 7 0 8 2 m l for the gamma distribution which compare with a maximum observed in the time period of interest of 6 1 m l the upper bounds are conservative estimates based on 100 per cent seismic release of the observed vertical neotectonic deformation glacio isostatic recovery is predominantly an elastic rather than a seismic process so the true value of m max is likely to be nearer the lower end of the quoted range

earthquake hazard after a mainshock in california after a strong earthquake the possibility of the occurrence of either significant aftershocks or an even stronger mainshock is a continuing hazard that threatens the resumption of critical services and reoccupation of essential but partially damaged structures a stochastic parametric model allows determination of probabilities for aftershocks and larger mainshocks during intervals following the mainshock the probabilities depend strongly on the model parameters which are estimated with bayesian statistics from both the ongoing aftershock sequence and from a suite of historic california aftershock sequences probabilities for damaging aftershocks and greater mainshocks are typically well constrained after the first day of the sequence with accuracy increasing with time

likelihood analysis of earthquake catalogues summary we apply several classes of stochastic multidimensional models to statistical analysis of earthquake catalogues using likelihood methods we investigate the importance of including different earthquake parameters in the model epicentral coordinates hypocentral depth time limits for interearthquake interaction and especially spatial distribution of earthquakes as well as spatial aftershock patterns results of this study combined with other investigations suggest that most distributions controlling earthquake interaction have a fractal or scale invariant form developed models are used for statistical analysis of several earthquake catalogues to evaluate parameters of earthquake occurrence these parameters are shown to be similar for shallow earthquakes of different magnitude ranges and seismogenic regions confirming self similarity of the earthquake process whereas intermediate earthquakes seem to emulate the pattern of shallow earthquake occurrence albeit at a much smaller aftershock rate deep earthquakes differ significantly in their properties predictability of standard shallow earthquake catalogues has been analysed we present evidence that for the best availabfe catalogues the predictability is close to 10 bits per earthquake several synthetic earthquake catalogues have been created and processed through the likelihood inversion scheme the results from likelihood analysis of these catalogues confirm our approach

using the etas model for catalog declustering and seismic background assessment the concept of background seismicity is strictly related to the identification of spontaneous and triggered earthquakes the definition of foreshocks main shocks and aftershocks is currently based on procedures depending on parameters whose values are notoriously assumed by subjective criteria we propose a method for recognizing the background and the induced seismicity statistically rather than using a binary distinction of the events in these two categories we prefer to assign to each of them a probability of being independent or triggered this probability comes from an algorithm based on the etas model a certain degree of subjectivity is still present in this procedure but it is limited by the possibility of adjusting the free parameters of the algorithm by rigorous statistical criteria such as maximum likelihood we applied the method to the seismicity of southern california and analyzed the sensitivity of the results to the free parameters in the algorithm finally we show how our statistical declustering algorithm may be used for mapping the background seismicity or the moment rate in a seismic area

seismic hazard estimate from background seismicity in southern california abstract we analyzed the historical seismicity in southern california to develop a rational approach for calculating the seismic hazard from background seismicity of magnitude 6 5 or smaller the basic assumption for the approach is that future earthquakes will be clustered spatially near locations of historical mainshocks of magnitudes equal to or greater than 4 we analyzed the declustered california seismicity catalog to compute the rate of earthquakes on a grid and then smoothed these rates to account for the spatial distribution of future earthquakes to find a suitable spatial smoothing function we studied the distance r correlation for southern california earthquakes and found that they follow a 1 r power law relation where increases with magnitude this result suggests that larger events are more clustered in space than smaller earthquakes assuming the seismicity follows the gutenberg richter distribution we calculated peak ground accelerations pga for 10 probability of exceedance in 50 yr pga estimates range between 0 25 and 0 35 g across much of southern california these ground motion levels are generally less than half the levels of hazard that are obtained using the entire seismic source model that also includes geologic and geodetic data we also calculated the overall uncertainty for the hazard map using a monte carlo method and found that the coefficient of variation is about 0 24 0 01 for much of the region

comparative performance of time invariant long range and short range forecasting models on the earthquake catalogue of greece 1 time invariant long range and short range forecasting models were fitted to the earthquake catalogue of greece for magnitudes 4 0 and greater to optimize their ability to forecast events of magnitude 6 0 and greater in the period 1966 1980 the models considered were stationary spatially uniform and spatially varying poisson models a long range forecasting model based on the precursory scale increase phenomenon with every earthquake regarded as a precursor according to scale and epidemic type short range forecasting models with spatially uniform and spatially varying spontaneous seismicity each of the models was then applied to the catalogue for 1981 2002 and their forecasting performance was compared using the log likelihood statistic the long range forecasting model performed substantially better than the time invariant models and the short range forecasting models performed substantially better again the results show that the information value to be gained from modeling temporal and spatial variation of earthquake occurrence rate at both long and short range is much greater than can be gained from modeling spatial variation alone

kernel estimation methods for seismic hazard area source modeling in probabilistic seismic hazard analysis the representation of seismic sources by area zones is a standard means of data reduction however where the association between seismicity and geology is complex as it is in many tectonic regimes the construction of zone geometry may become contentiously subjective and ambiguities may end up being resolved through appeal to the nonscientific rule of conservatism or pragmatism although consideration of alternative zonations within a logic tree framework provides a channel for some of the uncertainty it does not address the fundamental validity of the zonation procedure itself in particular neither the minimal assumption of uniform seismicity within a zone nor the euclidean geometry of a zone accord with the fractal spatial distribution of seismicity and the magnitude insensitivity of zonation ignores the spatial extent and correlations of different sized earthquakes an alternative procedure for area source modeling avoids euclidean zones and is based statistically on kernel estimation of the activity rate density inferred from the regional earthquake catalog the form of kernel is governed by the concepts of fractal geometry and self organized criticality with the bandwidth scaling according to magnitude in contrast with zonal models for intraplate regions the kernel estimation methodology makes provision for moderate earthquakes to cluster spatially while larger events may migrate over sizeable distances

in pursuit of anomalies analyzing the poleward transport of atlantic water with surface drifters we examine the trajectories of 168 drifters as a proxy for atlantic water flowing through the nordic seas the drifters were released at or passed through the svinoy section off the west coast of norway for comparison we generate a set of synthetic trajectories using a stochastic model with a range of diffusivities with the both sets we determine the transit times of both drifters and particles from svinoy to arctic gateways the barents sea and spitsbergen the mean arrival times to these locations are roughly 200 and 500 days respectively this implies ample time for cooling of the surface waters which increases densities and permits subduction before reaching the arctic however a range of transit times is seen some parcels reach fram strait in only 4 months while others are still in the southern nordic seas after 2 years the results do not support the idea that temperature or salinity anomalies can exist as coherent packets the drifters passing svinoy when treated as a group quickly spread over large distances mixing with water in the norwegian and lofoten basins thus an anomaly entering the nordic seas would quickly be obliterated however the velocity of the clusters center of mass is consistent with anomaly propagation speeds inferred previously from hydrographic measurements suggesting the observed variability is advective in nature

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

local magnitudes and apparent variations in seismicity rates in southern california redetermination of local magnitudes for moderate earthquakes recorded by the southern california seismographic network scsn from 1932 to 1990 has shown that the magnitudes have not been consistently determined over that time period the amplitudes of ground velocities recorded on wood anderson instruments were systematically overestimated prior to 1944 compared to present reading procedures leading to a significant overestimation of local magnitudes in addition the change from human to computerized estimation of event magnitude from a suite of amplitudes in 1975 led to slightly lower event magnitudes for the time after 1975 compared to the time before these changes contribute to an apparently higher rate of seismicity in the 1930s and 1940s than later in the catalog which had been interpreted as a decrease in seismicity rate after the 1952 kern county m w 7 5 earthquake wood anderson amplitudes have been reread and consistent magnitudes recalculated using uniform procedures for all earthquakes with a catalog magnitude of 4 5 and greater within the scsn from 1932 to 1943 and those with a catalog magnitude of 4 8 and greater from 1944 to 1990 so as to create a complete list of all earthquakes with a modern local magnitude of 5 0 or greater using these new magnitudes we find that the rate of m l 5 0 and greater earthquakes in southern california over this 59 year period to be poissonian with no changes in rate significant above the 90 level from this rate in any 30 year period the poissonian probability of a m 6 earthquake is 99 7 the probability of an m 7 earthquake is 65 and the probability of an m 8 event is 18

application of a modified pattern informatics method to forecasting the locations of future large earthquakes in the central japan we propose a modification of the pattern informatics pi method that has been developed for forecasting the locations of future large earthquakes this forecast is based on analyzing the space time patterns of past earthquakes to find possible locations where future large earthquakes are expected to occur a characteristic of our modification is that the effect of errors in the locations of past earthquakes on the output forecast is reduced we apply the modified and original methods to seismicity in the central part of japan and compared the forecast performances we also invoke the relative intensity ri of seismic activity and randomized catalogs to constitute null hypotheses we do statistical tests using the molchan and relative operating characteristic roc diagrams and the log likelihoods and show that the forecast for using the modified pi method is generally better than the competing original pi forecast and the forecasts from the null hypotheses using the bootstrap technique with monte carlo simulations we further confirm that earthquake sequences simulated based on the modified pi forecast can be statistically the same as the real earthquake sequence so that the forecast is acceptable the main and innovative science in this paper is the modification of the pi method and the demonstration of its applicability showing a considerable promise as an intermediate term earthquake forecasting tool

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

mixture models for improved short term earthquake forecasting abstract the short term earthquake probability step forecasting model applies the omori utsu aftershock decay relation and the gutenberg richter frequency magnitude relation to clusters of earthquakes it is mainly intended to forecast aftershock activity and depends on a time invariant background model to forecast most of the major earthquakes on the other hand the long range earthquake forecasting model eepas every earthquake a precursor according to scale exploits the precursory scale increase phenomenon and associated predictive scaling relations to forecast the major earthquakes months years or decades in advance depending on magnitude both models are shown to be more informative than time invariant models of seismicity by forming a mixture of the two we aim to create an even more informative short term forecasting model using the advanced national seismic system catalog of california over the period 1984 2004 the optimal mixture model for forecasting earthquakes with m 5 0 is a convex linear combination consisting of 0 42 of the eepas forecast and 0 58 of the step forecast this mixture gives an average probability gain of more than 2 compared to each of the individual models several different mixture models will be submitted to the csep testing center at the southern california earthquake center to ascertain whether or not this result is borne out by real time tests of the models against future earthquakes

a long term earthquake rate model for the central and eastern united states from smoothed seismicity abstract i present a long term earthquake rate model for the central and eastern united states from adaptive smoothed seismicity by employing pseudoprospective likelihood testing l test i examined the effects of fixed and adaptive smoothing methods and the effects of catalog duration and composition on the ability of the models to forecast the spatial distribution of recent earthquakes to stabilize the adaptive smoothing method for regions of low seismicity i introduced minor modifications to the way that the adaptive smoothing distances are calculated across all smoothed seismicity models the use of adaptive smoothing and the use of earthquakes from the recent part of the catalog optimizes the likelihood for tests with m 2 7 and m 4 0 earthquake catalogs the smoothed seismicity models optimized by likelihood testing with m 2 7 catalogs also produce the highest likelihood values for m 4 0 likelihood testing thus substantiating the hypothesis that the locations of moderate size earthquakes can be forecast by the locations of smaller earthquakes the likelihood test does not however maximize the fraction of earthquakes that are better forecast than a seismicity rate model with uniform rates in all cells in this regard fixed smoothing models perform better than adaptive smoothing models the preferred model of this study is the adaptive smoothed seismicity model based on its ability to maximize the joint likelihood of predicting the locations of recent small to moderate size earthquakes across eastern north america the preferred rate model delineates 12 regions where the annual rate of m 5 earthquakes exceeds 2 10 3 although these seismic regions have been previously recognized the preferred forecasts are more spatially concentrated than the rates from fixed smoothed seismicity models with rate increases of up to a factor of 10 near clusters of high seismic activity online material figures of minimum magnitude determination b value estimation and maps of earthquake rate and forecasts and tables of optimized neighbor numbers and smoothing distances

currently active regions of decelerating accelerating seismic strain in central asia 1 accelerating preshock seismic strain in a broad critical region and decelerating preshock seismic strain in a narrower seismogenic region constitute a model for intermediate term prediction of strong main shocks an effort is made in the present work for a forward test of the decelerating accelerating seismic strain d as model by identifying such patterns and estimating the corresponding probably ensuing strong main shocks m 7 0 in central asia 20 n 45 n 42 e 105 e five such patterns have been identified and the origin time magnitude and epicentral geographic coordinates of each of the corresponding main shocks have been estimated predicted model uncertainties of the estimated time magnitude and space parameters of these probably ensuing main shocks as well as appropriate statistical tests against a standard gutenberg richter seismicity distribution are also presented to allow a future objective evaluation of the model s efficiency for intermediate term earthquake prediction

earthquake forecasting in diverse tectonic zones of the globe we present a simple method for long and short term earthquake forecasting estimating earthquake rate per unit area time and magnitude for illustration we apply the method to the pacific plate boundary region and the mediterranean area surrounding italy and greece our ultimate goal is to develop forecasting and testing methods to validate or falsify common assumptions regarding earthquake potential our immediate purpose is to extend the forecasts we made starting in 1999 for the northwest and southwest pacific to include somewhat smaller earthquakes and then adapt the methods to apply in other areas the previous forecasts used the cmt earthquake catalog to forecast magnitude 5 8 and larger earthquakes like our previous forecasts the new ones here are based on smoothed maps of past seismicity and assume spatial clustering our short term forecasts also assume temporal clustering an important adaptation in the new forecasts is to abandon the use of tensor focal mechanisms this permits use of earthquake catalogs that reliably report many smaller quakes with no such mechanism estimates the result is that we can forecast earthquakes at higher spatial resolution and down to a magnitude threshold of 4 7 the new forecasts can be tested far more quickly because smaller events are considerably more frequent also our previous method used the focal mechanisms of past earthquakes to estimate the preferred directions of earthquake clustering however the method made assumptions that generally hold in subduction zones only the new approach escapes those assumptions in the northwest pacific the new method gives estimated earthquake rate density very similar to that of the previous forecast

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

explanation of temporal clustering of tsunami sources using the epidemic type aftershock sequence model temporal clustering of tsunami sources is examined in terms of a branching process model it previously was observed that there are more short interevent times between consecutive tsunami sources than expected from a stationary poisson process the epidemic type aftershock sequence etas branching process model is fitted to tsunami catalog events using the earthquake magnitude of the causative event from the centennial and global centroid moment tensor cmt catalogs and tsunami sizes above a completeness level as a mark to indicate that a tsunami was generated the etas parameters are estimated using the maximum likelihood method the interevent distribution associated with the etas model provides a better fit to the data than the poisson model or other temporal clustering models when tsunamigenic conditions magnitude threshold submarine location dip slip mechanism are applied to the global cmt catalog etas parameters are obtained that are consistent with those estimated from the tsunami catalog in particular the dip slip condition appears to result in a near zero magnitude effect for triggered tsunami sources the overall consistency between results from the tsunami catalog and that from the earthquake catalog under tsunamigenic conditions indicates that etas models based on seismicity can provide the structure for understanding patterns of tsunami source occurrence the fractional rate of triggered tsunami sources on a global basis is approximately 14 online material figures of residual analysis for tsunami and earthquake catalogs

seismic cycles and earthquake predictability on east pacific rise transform faults the concept of a seismic cycle where the stress on a fault repeatedly builds up over a long period of time and then is rapidly released in a large earthquake influences studies of both the basic physics of faulting and applied research aimed at estimating earthquake hazards this hypothesis suggests that large earthquakes might be quasi periodic and that the probability of a particular portion of a fault rupturing twice in quick succession should be low however this basic hypothesis has been difficult to verify owing to the long repeat times of the largest earthquakes on most faults east pacific rise epr transform faults are an advantageous location to evaluate the seismic cycle hypothesis owing to their fast slip rates and the moderate size m w 6 of their largest earthquakes using surface wave based determinations of the relative separations between earthquake centroids i document 16 pairs of m w 5 5 events that had overlapping ruptures the distribution of interevent times for these pairs is tightly clustered around 5 yr with a coefficient of variation 0 2 indicating that quasi periodicity may be prevalent for the largest events on these faults moreover i find no pairs of overlapping m w 5 5 6 2 earthquakes separated by less than 50 cm of elapsed plate motion indicating that the two basic features of the seismic cycle hypothesis are evident in the timing of large epr transform mainshocks i have also confirmed earlier results demonstrating a high degree of short term predictability of epr mainshocks by combining teleseismic and hydroacoustic earthquake catalogs thus there appears to be a high degree of both short and long term predictability on epr transforms

new seismic gap hypothesis five years after we use earthquake data from 1989 1994 to test a forecast by nishenko based on the seismic gap theory we refer to this forecast as the new seismic gap hypothesis because it is the first global forecast based on the seismic gap hypothesis that considers the recurrence time and characteristic earthquake magnitude specific to each plate boundary segment nishenko s forecasts gave probabilities that each of about 100 zones would be filled by characteristic earthquakes during periods of 5 10 and 20 years beginning on the first day of 1989 only the first of these can be tested now we used three tests based on 1 the total number of zones filled by characteristic earthquakes 2 the likelihood that the observed list of filled zones would result from a process with the probabilities specified in nishenko s hypothesis and 3 the likelihood ratio to that of a poissonian null hypothesis the null hypothesis uses a smoothed version of seismicity since 1977 and assumes a gutenberg richter magnitude distribution we used both the harvard centroid moment tensor and the national oceanic and atmospheric administration preliminary determination of epicenters catalogs in our test we also used several different magnitude cutoffs in our tests because nishenko s forecast did not specify a clear relationship between the characteristic earthquake magnitude and the threshold magnitude for a successful prediction using a strict interpretation that only earthquakes equal to or larger than the characteristic magnitude should be counted both catalogs show only two qualifying earthquakes in the entire area covered by the forecast the predicted number is 9 2 and the discrepancy is too large to result from chance at the 99 confidence level the new seismic gap hypothesis predicts too many characteristic earthquakes for three reasons first forecasts were made for some zones specifically because they had two or more earthquakes in the previous centuries biasing the estimated earthquake rate second open intervals before the first event and after the last event are excluded in calculation of recurrence rate third the forecast assumes that all slip in each zone is released in characteristic earthquakes of the same size while in fact considerable slip is released by both smaller and larger earthquakes the observed size distribution of earthquakes is inconsistent with the characteristic hypothesis instead of a deficit of earthquakes above the characteristic limit earthquake numbers are distributed according to the standard gutenberg richter relation by lowering the magnitude threshold for qualifying earthquakes it is possible to reduce the discrepancy between the observed and predicted number of earthquakes to an acceptable level however for every magnitude threshold we tried the new seismic gap model failed the test on the number of filled zones or the likelihood ratio test or both at least at the 95 confidence level

single link cluster analysis of earthquake aftershocks decay laws and regional variations using single link cluster analysis the authors investigate how various properties of aftershock sequences depend on their tectonic regime and focal depth for international seismological centre earthquakes of m sub b ge 4 8 they find that earthquakes deeper than 70 km have the fewest and smallest aftershock sequences even after accounting for differences in detectability and maximum magnitude they find that ridge transform earthquakes have smaller aftershock sequences that shallow subduction zone earthquakes among different subduction zones they find that zones with high moment release rates possess larger aftershock sequences comparing ridge transform zones they find those with slower spreading rates possess larger aftershock sequences by transposing origin times of several different aftershock sequences as if all had main shocks occurring at time zero they are able to study the properties of aftershock sequences which individually have too few aftershocks to study by other means secondary events determined by single link cluster analysis follow a modified omori s power law decay for time separations of 0 1 day to 20 days from the parent event with p values ranging from 0 539 plus minus 0 022 intermediate and deep focus earthquakes to 0 928 plus minus 0 024 ridge transform earthquakes they find that earthquake foreshocks and multiplets also follow a modified omori s law atmore greater times from the main shock the decay is steeper than a power law decay more like an exponential decay aftershocks in the adak catalog m sub b ge 2 0 show a marked decrease in activity between 40 and 50 km depth they speculate that the observed differences in number of aftershocks and p values may be caused by variations in fault heterogeneity or in fluid pressures less

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

earthquake potential in and around china estimated from past earthquakes 1 we present an earthquake potential estimate for magnitude 5 4 or larger earthquakes for china the potential is expressed as the rate density or the probability per unit area magnitude and time and it is based on smoothed seismicity we constructed a special earthquake catalog which combines previous catalogs covering different times after deriving regression relationships we estimated moment magnitudes for some events then we used the special catalog for constructing our smoothed seismicity model and testing it retrospectively using maximum likelihood we estimated the completeness threshold the b value and the corner magnitude we adopted a kind of gutenberg richter distribution with modifications at higher magnitude and assumed a uniform b value and upper magnitude limit derived from the special catalog from smoothed seismicity we estimated local a values we have begun a prospective test finding that earthquakes since the beginning of 2000 are quite compatible with the model

a comparison of characteristic parameters of mining related and tectonic seismic aftershock sequences abstract the temporal decay pattern of seismicity following rock bursts and large magnitude events is studied for aftershock sequences in several mines in ontario canada the decay phenomenon is described by the so called modified omori s law the dependency of the parameters k c and p with the magnitude of large mine seismic events is analyzed a total of eleven mining related seismic sequences with mainshock magnitudes ranging from 0 5 to 4 0 mn nuttli magnitude scale and from four different mine environments are examined results including the calculation of the gutenberg richter s and reasenberg jones parameters b and a are compared with previous research in tectonic seismicity using available data from new zealand italy and u s a further parameters were derived and applied in a correlation study of mining related and tectonic events the study revealed a good correlation between the productivity parameter a and b values particularly the b values show significant different number ranges for mining related and tectonic data which was applied to derive a direct numerical relationship between mining related and tectonic parameters and the aftershock number estimation finally numerical values for the b values in mining related seismic activity were obtained

circum pacific seismic potential 1989 1999 the seismic potential for 96 segments of simple plate boundaries around the circum pacific region is presented in terms of the conditional probability for the occurrence of either large or great interplate earthquakes during the next 5 10 and 20 years i e 1989 1994 1989 1999 and 1989 2009 this study represents the first probabilistic summary of seismic potential on this scale and involves the comparison of plate boundary segments that exhibit varying recurrence times magnitudes and tectonic regimes presenting these data in a probabilistic framework provides a basis for the uniform comparison of seismic hazard between these differing fault segments as well as accounting for individual variations in recurrence time along a specific fault segment and uncertainties in the determination of the average recurrence time

probability map of the next m 5 5 earthquakes in italy 1 the main goal of this work is to provide a probability map for the next moderate to large earthquakes m 5 5 in italy for this purpose we apply a new nonparametric multivariate model to characterize the spatiotemporal distribution of earthquakes the method is able to account for tectonics physics parameters that can potentially influence the spatiotemporal variability and tests their relative importance moreover it allows straightforward testing of a variety of hypothesis such as seismic gap cluster and poisson hypothesis the method has been applied to italian seismicity of the last four centuries for earthquakes with m 5 5 italy has been divided into 61 irregular zones representing areas with homogeneous tectonic regime resulting from active stress data besides the magnitude and the time of the earthquakes the model includes information on the tectonic stress regime the homogeneity of its orientation the number of active faults the dimension of the area and the homogeneity of the topography the time distribution of the m 5 5 earthquakes appears clustered in time for a few years after an event and then the distribution becomes similar to a memoryless poisson process leading to a time dependent probability map this map shows that the most likely regions where the next moderate to large earthquakes may occur are friuli umbria marche and part of southern apennines and the calabrian arc

a ten year earthquake occurrence model for italy the recent m w 6 3 destructive l aquila earthquake has further stimulated the improvement of the italian operational earthquake forecasting capability at different time intervals here we describe a medium term 10 year forecast model for m w 5 5 earthquakes in italy that aims at opening new possibilities for risk mitigation purposes while a longer forecast yielded by the national seismic hazard map is the primary component in establishing the building code a medium term earthquake forecast model may be useful to prioritize additional risk mitigation strategies such as the retrofitting of vulnerable structures in particular we have developed an earthquake occurrence model for a 10 year forecast that consists of a weighted average of time independent and different types of available time dependent models based on seismotectonic zonations and regular grids the inclusion of time dependent models marks a difference with the earthquake occurrence model of the national seismic hazard map and it is motivated by the fact that at the 10 year scale the contribution of time dependency in the earthquake occurrence process may play a major role the models are assembled through a simple averaging scheme whereby each model is weighted through the results of a retrospective testing phase similar to the ones carried out in the framework of the collaboratory for the study of earthquake predictability in this way the most hazardous italian areas in the next ten years will arise from a combination of distinct models that place more emphasis on different aspects of the earthquake occurrence process such as earthquake clustering historical seismic rate and the presence of delayed faults capable of large events finally we report new challenges and possible developments for future updating of the model

universality of the seismic moment frequency relation we analyze the seismic moment frequency relation in various depth ranges and for different seismic regions using flinn engdahl s regionalization of global seismicity three earthquake lists of centroid moment tensor data have been used the harvard catalog the usgs catalog and the huang et al 1997 catalog of deep earthquakes the results confirm the universality of the values and the maximum moment for shallow earthquakes in continental regions as well as at and near continental boundaries moreover we show that although fluctuations in earthquake size distribution increase with depth the values for earthquakes in the depth range of 0 500 km exhibit no statistically significant regional variations the regional variations are significant only for deep events near the 660 km boundary for declustered shallow earthquake catalogs and deeper events we show that the worldwide values have the same value of 0 60 0 02 this finding suggests that the value is a universal constant we investigate the statistical correlations between the numbers of seismic events in different depth ranges and the correlation of the tectonic deformation rate and seismic activity the number of earthquakes above a certain threshold level per year the high level of these correlations suggests that seismic activity indicates tectonic deformation rate in subduction zones combined with the universality of the value this finding implies little if any variation in maximum earthquake seismic moment among various subduction zones if we assume that earthquakes of maximum size are similar in different depth ranges and the seismic efficiency coefficient is close to 100 for shallow seismicity then we can estimate for deeper earthquakes for intermediate earthquakes 5 and 1 for deep events these results may lead to new theoretical understanding of the earthquake process and better estimates of seismic hazard

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

bayesian inference of stress release models applied to some italian seismogenic zones summary in this paper we evaluate the seismic hazard of a region in southern italy by analysing stress release models from the bayesian viewpoint the data are drawn from the most recent version of the parametric catalogue of italian earthquakes for estimation we just use the events up to 1992 then we forecast the date of the next event through a stochastic simulation method and we compare the result with the really occurred shocks in the span 1993 2002 the original version of the stress release model proposed by vere jones in 1978 transposes reid s elastic rebound theory in the framework of stochastic point processes since the nineties enriched versions of this model have appeared in the literature applied to historical catalogues from china iran japan they envisage the identification of independent or interacting tectonic subunits constituting the region under exam it follows that the stress release models designed for regional analyses are evolving towards studies on fault segments realizing some degree of convergence to those models that start from an individual fault and considering the interactions with nearby segments are driven to studies on regional scale the optimal performance of the models we consider depends on a set of choices among which the seismogenic region and possible subzones the threshold magnitude the length of the time period in this paper we focus our attention on the influence of the subdivision of the region under exam into tectonic units in the light of the recent studies on the fault segmentation model of italy we propose a partition of sannio matese ofanto irpinia one of the most seismically active region in southern italy the results show that the performance of the stress release models improves in terms of both fitting and forecasting when the region is split up into parts including new information about potential seismogenic sources

a statistical investigation of the earthquake predictions using lurr in terms of the spatial scanning of lurr load unload response ratio we have been predicting the seismic tendency within the next year for the mainland of china from 1995 to 2003 in order to make the quantitative retrospective assessment of lurr method we compare the results with poisson null hypothesis the results show that the prediction by lurr method is much better than poisson hypothesis

reading a 400 000 year record of earthquake frequency for an intraplate fault our understanding of the frequency of large earthquakes at timescales longer than instrumental and historical records is based mostly on paleoseismic studies of fast moving plate boundary faults similar study of intraplate faults has been limited until now because intraplate earthquake recurrence intervals are generally long 10s to 100s of thousands of years relative to conventional paleoseismic records determined by trenching long term variations in the earthquake recurrence intervals of intraplate faults therefore are poorly understood longer paleoseismic records for intraplate faults are required both to better quantify their earthquake recurrence intervals and to test competing models of earthquake frequency e g time dependent time independent and clustered we present the results of u th dating of calcite veins in the loma blanca normal fault zone rio grande rift new mexico united states that constrain earthquake recurrence intervals over much of the past 550 ka the longest direct record of seismic frequency documented for any fault to date the 13 distinct seismic events delineated by this effort demonstrate that for 400 ka the loma blanca fault produced periodic large earthquakes consistent with a time dependent model of earthquake recurrence however this time dependent series was interrupted by a cluster of earthquakes at 430 ka the carbon isotope composition of calcite formed during this seismic cluster records rapid degassing of co2 suggesting an interval of anomalous fluid source in concert with u th dates recording decreased recurrence intervals we infer seismicity during this interval records fault valve behavior these data provide insight into the long term seismic behavior of the loma blanca fault and by inference other intraplate faults

assessing historical rate changes in global tsunami occurrence summary the global catalogue of tsunami events is examined to determine if transient variations in tsunami rates are consistent with a poisson process commonly assumed for tsunami hazard assessments the primary data analyzed are tsunamis with maximum sizes 1m the record of these tsunamis appears to be complete since approximately 1890 a secondary data set of tsunamis 0 1m is also analyzed that appears to be complete since approximately 1960 various kernel density estimates used to determine the rate distribution with time indicate a prominent rate change in global tsunamis during the mid 1990s less prominent rate changes occur in the early and mid 20th century to determine whether these rate fluctuations are anomalous the distribution of annual event numbers for the tsunami catalogue is compared to poisson and negative binomial distributions the latter of which includes the effects of temporal clustering compared to a poisson distribution the negative binomial distribution model provides a consistent fit to tsunami event numbers for the 1m data set but the poisson null hypothesis cannot be falsified for the shorter duration 0 1m data set temporal clustering of tsunami sources is also indicated by the distribution of interevent times for both data sets tsunami event clusters consist only of two to four events in contrast to protracted sequences of earthquakes that make up foreshock main shock aftershock sequences from past studies of seismicity it is likely that there is a physical triggering mechanism responsible for events within the tsunami source mini clusters in conclusion prominent transient rate increases in the occurrence of global tsunamis appear to be caused by temporal grouping of geographically distinct mini clusters in addition to the random preferential location of global m 7 earthquakes along offshore fault zones

stress transferred by the 1995 mw 6 9 kobe japan shock effect on aftershocks and future earthquake probabilities the kobe earthquake struck at the edge of the densely populated osaka kyoto corridor in southwest japan we investigate how the earthquake transferred stress to nearby faults altering their proximity to failure and thus changing earthquake probabilities we find that relative to the pre kobe seismicity kobe aftershocks were concentrated in regions of calculated coulomb stress increase and less common in regions of stress decrease we quantify this relationship by forming the spatial correlation between the seismicity rate change and the coulomb stress change the correlation is significant for stress changes greater than 0 2 1 0 bars 0 02 0 1 mpa and the nonlinear dependence of seismicity rate change on stress change is compatible with a state and rate dependent formulation for earthquake occurrence we extend this analysis to future mainshocks by resolving the stress changes on major faults within 100 km of kobe and calculating the change in probability caused by these stress changes transient effects of the stress changes are incorporated by the state dependent constitutive relation which amplifies the permanent stress changes during the aftershock period earthquake probability framed in this manner is highly time dependent much more so than is assumed in current practice because the probabilities depend on several poorly known parameters of the major faults we estimate uncertainties of the probabilities by monte carlo simulation this enables us to include uncertainties on the elapsed time since the last earthquake the repeat time and its variability and the period of aftershock decay we estimate that a calculated 3 bar 0 3 mpa stress increase on the eastern section of the arima takatsuki tectonic line attl near kyoto causes fivefold increase in the 30 year probability of a subsequent large earthquake near kyoto a 2 bar 0 2 mpa stress decrease on the western section of the attl results in a reduction in probability by a factor of 140 to 2000 the probability of a mw 6 9 earthquake within 50 km of osaka during 1997 2007 is estimated to have risen from 5 6 before the kobe earthquake to 7 11 afterward during 1997 2027 it is estimated to have risen from 14 16 before kobe to 16 22

the linked stress release model for spatio temporal seismicity formulations procedures and applications summary the linked stress release model is based on the build up of stress through elastic rebound and its dissipation in the form of earthquakes in addition stress can be transferred between large scale geological or seismic features the model can be statistically fitted to both historical and synthetic seismicity catalogues and through simulation can be used to create probabilistic forecasts of earthquake risk we review the genesis of the model provide some observations on forecasting using the model and follow with a comprehensive review of applications to date a systematic procedure for identification of the best model is illustrated by data from the persian region we then consider the evaluation of fitted models using residual point processes and information gains implications of the use of benioff strain rather than seismic moment are discussed the sensitivity of the model to regionalization magnitude errors catalogue incompleteness catalogue size and declustering magnitude cut off is then considered in detail with reference to data from north china the latter data are also used to illustrate the model evaluation techniques introduced earlier some technical material on numerical fitting simulation and calculation of the information gain is given in an appendix

gear1 a global earthquake activity rate model constructed from geodetic strain rates and smoothed seismicity global earthquake activity rate model 1 gear1 estimates the rate of shallow earthquakes with magnitudes 6 9 everywhere on earth it was designed to be reproducible and testable our preferred hybrid forecast is a log linear blend of two parent forecasts based on the global centroid moment tensor cmt catalog smoothing 4602 m 5 767 shallow earthquakes 1977 2004 and the global strain rate map version 2 1 smoothing 22 415 global positioning system velocities optimized to best forecast the 2005 2012 global cmt catalog strain rate is a proxy for fault stress accumulation and earthquakes indicate stress release so a multiplicative blend is desirable capturing the strengths of both approaches this preferred hybrid forecast outperforms its seismicity and strain rate parents the chance that this improvement stems from random seismicity fluctuations is less than 1 the preferred hybrid is also tested against the independent parts of the international seismological centre global earthquake model catalog m 6 8 during 1918 1976 with similar success gear1 is an update of this preferred hybrid comparing gear1 to the uniform california earthquake rupture forecast version 3 ucerf3 net earthquake rates agree within 4 at m 5 8 and at m 7 0 the spatial distribution of ucerf3 epicentroids most resembles gear1 after ucerf3 is smoothed with a 30 km kernel because ucerf3 has been constructed to derive useful information from fault geometry slip rates paleoseismic data and enhanced seismic catalogs not used in our model this is encouraging to build parametric catastrophe bonds from gear1 one could calculate the magnitude for which there is a 1 or any annual probability of occurrence in local regions online material discussion of forecast scoring metrics tables of scoring results and source code and data files needed to reproduce forecast