evaluation of the results for an intermediate term prediction of the 8 january 2006 mw 6 9 cythera earthquake in the southwestern aegean during the past few decades the critical earthquake model which is based on observations concerning accelerating seismic deformation and concepts of the critical point dynamics has been proposed by various seismologists as a useful tool for intermediate term earthquake prediction a refined approach of this model has been previously applied to search for preshock critical regions in the southern aegean using all available data until the middle of 2002 a critical region corre sponding to a large mainshock had been identified papazachos et al 2002a b in the southwestern part of the aegean near the cythera island the predicted in 2002 parameters for this ensuing earthquake are u 36 5 n k 22 7 e for the epicental geographic coordinates with a model uncertainty of 120 km focal depth 100 km moment magnitude m 6 9 0 5 and origin time tc 2006 4 2 0 the generation of the strong cythera earthquake on 8 january 2006 with m 6 9 epicenter coordinates u 36 2 n and k 23 4 e and a focal depth of h 65 km satisfies this intermediate term prediction the region where significant macroseismic effects were anticipated from the predicted mainshock cythera south peloponnesus west crete and west cyclades corresponds to the area where damage by the 8 january 2006 strong earthquake has been observed the verification of this prediction is strong evidence that the intermediate term prediction of strong earthquakes is potentially feasible but additional forward testing of the model is needed to validate this result

earthquake activity related to seismic cycles in a model for a heterogeneous strike slip fault we investigate the evolution of seismicity within large earthquake cycles in a model of a discrete strike slip fault in elastic solid the model dynamics is governed by realistic boundary conditions consisting of constant velocity motion of regions around the fault static kinetic friction and dislocation creep along the fault and 3d elastic stress transfer the fault consists of brittle parts which fail during earthquakes and undergo small creep deformation between events and aseismic creep cells which are characterized by high ongoing creep motion this mixture of brittle and creep cells is found to generate realistic aftershock sequences which follow the modified omori law and scale with the mainshock size furthermore we find that the distribution of interevent times of the simulated earthquakes is in good agreement with observations the temporal occurrence however is magnitude dependent in particular the small events are clustered in time whereas the largest earthquakes occur quasiperiodically averaging the seismicity before several large earthquakes we observe an increase of activity and a broadening scaling range of magnitudes when the time of the next mainshock is approached these results are characteristics of a critical point behavior the presence of critical point dynamics is further supported by the evolution of the stress field in the model which is compatible with the observation of accelerating moment release in natural fault systems

diagnosis of time of increased probability of strong earthquakes in different regions of the world algorithm cn abstract an algorithm for intermediate term earthquake prediction is suggested which allows diagnosis of the times of increased probability of strong earthquakes tips tips are declared for the time period of one year and an area with linear dimensions of a few hundred kilometers and can be extended in time the algorithm is based on the following traits of an earthquake flow level of seismic activity its temporal variation clustering of earthquakes in space and time their concentration in space and their long range interaction the algorithm is normalized so that it can be applied in various regions without readaptation tips diagnosed by the algorithm precede 80 of strong earthquakes and take on average 24 of the total time

fractal structure of spatial distribution of microfracturing in rock summary a constant stress fracture experiment of oshima granite was carried out at the confining pressure of 40mpa hypocentres of 2064 acoustic emissions were located during the experiment using the correlation integral we found that the spatial distribution of hypocentres of acoustic emission is a fractal and that the fractal dimension decreases with the evolution of rock fracturing the spatial distribution of earthquake s hypocentres reveals fractals ranging from regional to worldwide distribution if we extrapolate from laboratory measurements it is possible to predict the occurrence of large earthquakes by the decrease in the fractal dimension

development of a combination approach for seismic hazard evaluation we developed a synth esis approach to augment current techniques for seismic hazard evaluation by combining four previously unrelated subjects the pattern informatics pi load unload response ratio lurr state vector sv and accelerating moment release amr methods since the pi is proposed in the premise that the change in the seismicity rate is a proxy for the change in the tectonic stress this method is used to quantify localized changes surrounding the epicenters of large earthquakes to objectively quantify the anomalous areas hot spots of the upcoming events on the short to intermediate term estimation we apply the lurr sv and amr methods to examine the hazard regions derived from the pi hot spots a predictive study of the 2014 earthquake tendency in chinese mainland using the seismic data from 1970 01 01 to 2014 10 01 shows that during jan 01 to oct 31 2014 most of the m 5 0 earthquakes especially the feb 12 m7 3 yutian may 30 m6 1 yingjiang aug 03 m6 5 ludian and oct 07 m6 6 earthquakes occurred in the seismic hazard regions predicted comparing the predictions produced by the pi and combination approaches it is clear that by using the combination approach we can screen out the false alarm regions from the pi estimation without reducing the hit rate and therefore effectively augment the predictive power of current techniques this provided evidence that the multi method combination approach may be a useful tool to detect precursory information of future large earthquakes

accelerating seismic release from a self correcting stochastic model 1 we investigate the conditions under which the stress release model a stochastic version of the elastic rebound model produces synthetic earthquake sequences characterized by accelerating seismic release asr in this model the level or stress of the process accumulates linearly with time through tectonic input and decreases as the result of earthquakes these stress drops correspond to some power of the energy released in the earthquakes either e0 5 benioff strain or e seismic moment earthquakes occur in a point process with rate controlled by the level of the process we hypothesize that the critical factor in the appearance of asr is the manner in which the event sizes depend on the level of the process this is modeled by the square root of energy released following either a tapered pareto or truncated gutenberg richter distribution with maximum earthquake size controlled by a tail off or truncation point as the tail off point becomes large so does the average size corresponding to an acceleration to criticality of the system we found that those cases where the underlying level of the process corresponded to accumulated seismic moment produced numerous asr sequences whereas those cases using accumulated benioff strain as the level did not these results suggest that the occurrence of asr is strongly dependent on how large earthquakes affect the dynamics of the fault system in which they are embedded and hopefully provide some insight into the mechanics of acceleration to criticality i e on the possible causes of occurrence nonoccurrence of asr

basement hydrogeology and fortification of the channel islands legacies of british and german military engineering the islands of jersey guernsey alderney and sark lie close to the normandy coast of france they expose a largely precambrian crystalline basement of metamorphic and igneous rocks jersey and alderney also expose some early palaeozoic clastic sediments and all have a thin but widespread quaternary sedimentary cover the three largest islands were progressively fortified by the british between the early 13th and mid 19th centuries and by german forces during occupation in world war ii a legacy illustrated by the castles forts and numerous german coastal fortifications that still adorn them a german military geologist based on jersey from mid 1941 to mid 1944 and a military geological team on guernsey and alderney during 1942 generated hydrogeological maps and reports that were then in advance of understanding of crystalline basement aquifers elsewhere in the british isles all the major documents have now been found in germany the usa and uk although none survived on the islands themselves geological mapping and hydrogeological studies postwar under the auspices of the british geological survey were completed without access to german data however german and british data together now facilitate an appraisal of the heavily stressed aquifers on these small hard rock islands over an unusually long 65 year timespan

an examination of the nature and dynamics of seismogenesis in south california usa based on non extensive statistical physics abstract we examine the nature of the seismogenetic system in south california usa by searching for evidence of complexity and non extensivity in the earthquake record we attempt to determine whether earthquakes are generated by a self excited poisson process in which case they are independent or by a critical process in which long range interactions in non equilibrium states are expected correlation emphasis is given to background seismicity i e to the rudimentary expression of the seismogenetic system we use the complete and homogeneous earthquake catalogue published by the south california earthquake data centre in which aftershocks are either included or have been removed by a stochastic declustering procedure we examine multivariate cumulative frequency distributions of earthquake magnitudes interevent time and interevent distance in the context of non extensive statistical physics which generalizes the additive boltzmann gibbs thermodynamics to non additive non extensive dynamic systems our results indicate that the seismogenetic systems of south california are generally sub extensive complex and certainly non poissonian background seismicity exhibits long range interaction as evidenced by the overall increase of correlation observed by declustering the earthquake catalogues as well as by the high correlation observed for earthquakes separated by long interevent distances the results compare very well with those obtained in previous work for the seismogenetic systems of north california specifically the walker lane eastern california shear zone on one hand and the san andreas fault system south california continental borderland region on the other appear to comprise fault networks with different dynamics and expression the former exhibits persistent very high correlation and has attributes of stationary self organized criticality soc the latter exhibits high correlation mainly at long ranges and has attributes of evolutionary of self organized criticality all in all our results are compatible with simulations of small world fault networks in which free boundary conditions at the surface allow for self organization and criticality to develop

accelerating moment release revisited examples of application to italian seismic sequences abstract from simple considerations we propose a revision of the accelerating moment release amr methodology for improving our knowledge of seismic sequences and then hopefully in a close future to reach the capability of predicting the main shock location and occurrence with sufficient accuracy the proposed revision is based on the introduction of a reduced benioff strain for the earthquakes of the seismic sequence where for the same magnitude and after a certain distance from the main shock epicentre the closer the events the more they are weighted in addition we retain the usual expressions proposed by the ordinary amr method for the estimation of the corresponding main shock magnitude although this parameter is the weakest of the analysis then we apply the revised method to four case studies in italy three of which are the most recent seismic sequences of the last 9 years culminating with a shallow main shock and one is instead a 1995 1996 swarm with no significant main shock the application of the r amr methodology provides the best results in detecting the precursory seismic acceleration when compared with those found by ordinary amr technique we verify also the stability of the results in space applying the analysis to real data with moving circles in a large area around each main shock epicentre and the efficiency of the revised technique in time comparing the results with those obtained when applying the same analysis to simulated seismic sequences

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

retrospective on the accelerating seismic release asr hypothesis controversy and new horizons abstract the hypothesis that large earthquakes may be preceded by a period of accelerating seismicity or accelerating seismic release asr was proposed about twenty years ago a compilation of almost one hundred peer reviewed publications on this topic since the late 1980s to the present day shows that the rate of asr studies increased gradually until 2004 but decreased afterwards this negative trend is amplified by a recent increase in the number of negative results and criticisms of the asr hypothesis the author suggests that much of the recent negativity regarding this topic is due to the formulation of this hypothesis as a power law fit to cumulative seismicity series this approach is intrinsically linked to the consensus for criticality evident from an overview of the asr literature to explain the emergence of power laws in earthquake populations the holistic view of the earth s crust as a complex system restricts seismicity pattern analyses to the study of main features such as power laws while a reductionist view would allow for more refined ones such a paradigm shift or sea change might be under way in the asr literature where in 2007 a new approach was proposed to explain the asr power law from combined concepts of elastic rebound and geometry reductionism versus holism is a fundamental problem that not only applies to the study of asr but also to the broader field of earthquake physics and earthquake predictability science

test of the predictability of the pi method for recent large earthquakes in and near tibetan plateau five large earthquakes of m 7 0 based on the magnitude scale of the china earthquake networks center occurred in and near the tibetan plateau during 2008 2014 including the wenchuan m8 0 earthquake on may 12 2008 bjt in this paper the tibetan plateau was chosen to be the study region and calculating parameters of pattern informatics pi method with grid of 1 1 and forecasting time interval of 8 years were employed for the retrospective study according to the previous studies for m7 earthquake forecasting the sliding step of forecasting interval was 1 year and the hotspot diagrams of each forecasting interval since 2008 were obtained year by year the relationships among the hotspots and the m 7 0 earthquakes that occurred during the forecast intervals were studied the predictability of pi method was tested by verification of receiveroperating characteristic curve roc and r score the results show that the successive obvious hotspots occurred during the sliding forecasting intervals before four of the five earthquakes while hotspots only occurred in one forecasted interval without successive evolution process before one of the five earthquakes which indicates that four of the five large earthquakes could be forecasted well by pi method test results of the predictability of pi method by roc and r score show that positive prospect of pi method could be expected for long term earthquake forecast

intermediate term earthquake prediction using the modified time to failure method in southern california abstract based on retrospective modeling of earthquakes from the southern california earthquake catalog along with previously published evaluations from the new madrid seismic zone the modified time to failure method may be used as an intermediate term earthquake prediction technique for locating and predicting the size and time of a future mainshock modeling previous mainshocks for hypothesis development indicates that the method predicts the actual magnitude of the mainshock to within approximately 0 5 magnitude units the error associated with the time of failure is approximately 1 1 years assuming the last precursory event is known when the last event in the precursory sequence is not known the predicted magnitude remains similar but the predicted time will require refinement as additional events are added with time to the sequence the mainshock location can also be identified within a circular region with a radius on the order of tens of kilometers criteria are provided for defining acceleration sequences and mainshock locations the criteria reduce the number of false predictions but also eliminate some mainshocks from our evaluation mainshocks as small as magnitude 5 5 occurring between 1980 and 1995 were evaluated from the southern california earthquake catalog scc the results were used in association with previous studies to develop a method that can be used for practical future prediction applications the modified time to failure method was used to search the scc for future mainshocks occurring after 17 august 1998 one region satisfied all the criteria and may be modeled by the modified time to failure method the region likely to have a mainshock is a 65 km radius area centered at 31 43 n 115 47 w northern baja california mexico the predicted magnitude is 6 36 0 55 and the predicted time of failure is 1998 565 7 25 98 1 127 years the addition of future precursory events will allow refinement of the predicted values

seismic activity on neighbouring faults as a long term precursor to large earthquakes in the san francisco bay area activity in moderate size earthquakes accelerated in the several decades before the large california earthquakes of 1989 1906 and 1868 this type of precursor seems to require the presence of several major faults in close enough proximity to one another that moderate size shocks are selectively triggered on surrounding faults during the latter stages of the cycle of strain buildup to large earthquakes it may be possible to use quantitative aspects of similar seismic precursors to make predictions of large earthquakes on timescales of a few years to one decade

seismicity precursors to large earthquakes unified in a stress accumulation framework 1 various seismicity patterns before large earthquakes have been reported in the literature they include foreshocks medium term acceleration and short term activation quiescence doughnut patterns and event migration the existence of these precursory patterns is however debated here we develop an approach based on the concept of stress accumulation to unify and categorize all claimed seismic precursors in a same physical framework we first extend the non critical precursory accelerating seismicity theory n c past which already explains most precursors to additionally include short term activation theoretical results are then compared to the time series observed prior to the 2009mw 6 3 l aquila italy earthquake we finally show that different precursory paths are possible before large earthquakes with possible coupling of different patterns or non occurrence of any this is described by a logic tree defined from the combined probabilities of occurrence of the mainshock at a given stress state and of precursory silent slip on the fault in the case of the l aquila earthquake the observed precursory path is coupling of quiescence and accelerating seismic release followed by activation these results provide guidelines for future research on earthquake predictability

the newest developments of load unload response ratio lurr the load unload response ratio lurr method is an intermediate term earthquake prediction approach that has shown considerable promise it is inspiring that its predictions using lurr have been improving since 2004 we have made a major breakthrough in intermediate term earthquake forecasting of the strong earthquakes on the chinese mainland using lurr and successfully predicted the pakistan earthquake with magnitude m 7 6 on october 8 2005 the causes for improving the prediction in terms of lurr have been discussed in the present paper

increased long range intermediate magnitude earthquake activity prior to strong earthquakes in california we study the space time relationships between strong earthquakes in california and the intermediate magnitude earthquakes that both precede and follow them all 11 earthquakes in california with nominal magnitudes greater than or equal to 6 8 from 1941 to 1993 were preceded by an increase in the rate of occurrence of earthquakes having magnitudes greater than 5 1 ten of the 11 earthquakes occurred when or shortly after the intermediate magnitude activity was greater than its 75th percentile three of these strong earthquakes are in a conventional space time foreshock aftershock relationship with others of the 11 strong events the precursory activity is concentrated in regions having linear dimensions of the order of a few hundred kilometers these dimensions are significantly larger than the estimated fracture lengths of the ensuing strong earthquakes the correlations are ill defined for smaller earthquakes and are almost unidentifiable for earthquakes with magnitudes less than about 4 6 the precursors to the strong earthquakes appear over a time interval of the order of 5 to 10 years before the strong earthquake although the onset was about 25 years before the san francisco earthquake in the case of the loma prieta and san francisco earthquakes the onset of increased activity appears to be relatively abrupt the increased activity is either switched off abruptly to distances of the order of hundreds of kilometers shortly after the occurrence of a strong earthquake or the strong events are themselves part of a precursory pattern of continuing high activity before a second strong earthquake that takes place soon thereafter with subsequent extinction of activity after it thus the intermediate magnitude precursors do not directly influence the time and location of the subsequent strong event but the strong event has a strong influence on the stress field in the vicinity of intermediate magnitude earthquakes to distances of the order of many times the scale size of the strong earthquake

can damage mechanics explain temporal scaling laws in brittle fracture and seismicity time delays associated with processes leading to a failure or stress relaxation in materials and earthquakes are studied in terms of continuum damage mechanics damage mechanics is a quasi empirical approach that describes inelastic irreversible phenomena in the deformation of solids when a rock sample is loaded there is generally a time delay before the rock fails this period is characterized by the occurrence and coalescence of microcracks which radiate acoustic signals of broad amplitudes these acoustic emission events have been shown to exhibit power law scaling as they increase in intensity prior to a rupture in case of seismogenic processes in the earth s brittle crust all earthquakes are followed by an aftershock sequence a universal feature of aftershocks is that their rate decays in time according to the modified omori s law a power law decay in this paper a model of continuum damage mechanics in which damage microcracking starts to develop when the applied stress exceeds a prescribed yield stress a material parameter is introduced to explain both laboratory experiments and systematic temporal variations in seismicity

evolving towards a critical point a review of accelerating seismic moment energy release prior to large and great earthquakes there is growing evidence that some proportion of large and great earthquakes are preceded by a period of accelerating seismic activity of moderate sized earthquakes these moderate earthquakes occur during the years to decades prior to the occurrence of the large or great event and over a region larger than its rupture zone the size of the region in which these moderate earthquakes occur scales with the size of the ensuing mainshock at least in continental regions a number of numerical simulation studies of faults and fault systems also exhibit similar behavior the combined observational and simulation evidence suggests that the period of increased moment release in moderate earthquakes signals the establishment of long wavelength correlations in the regional stress field the central hypothesis in the critical point model for regional seismicity is that it is only during these time periods that a region of the earth s crust is truly in or near a self organized critical soc state such that small earthquakes are capable of cascading into much larger events the occurrence of a large or great earthquake appears to dissipate a sufficient proportion of the accumulated regional strain to destroy these long wavelength stress correlations and bring the region out of a soc state continued tectonic strain accumulation and stress transfer during smaller earthquakes eventually re establishes the long wavelength stress correlations that allow for the occurrence of larger events these increases in activity occur over longer periods and larger regions than quiescence which is usually observed within the rupture zone of a coming large event the two phenomena appear to have different physical bases and are not incompatible with one another

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

the lithosphere of the earth as a nonlinear system with implications for earthquake prediction the lithosphere of the earth can be viewed as a hierarchy of volumes from tectonic plates to grains of rock their relative movement against the forces of friction and cohesion is realized to a large extent through earthquakes the movement is controlled by a wide variety of independent processes concentrated in the thin boundary zones between the volumes a boundary zone has a similar hierarchical structure consisting of volumes separated by boundary zones etc altogether these processes transform the lithosphere into a large nonlinear system featuring instability and deterministic chaos from this background some integral grossly averaged empirical regularities emerge indicating a wide range of similarity collective behavior and the possibility of intermediate term earthquake prediction

a model of damage mechanics for the deformation of the continental crust 1 we derive a continuum rheology for the deformation of the continental crust using continuum damage mechanics it is hypothesized that when a constant strain rate is applied to a solid material the stress and damage increase until failure occurs which is analogous to an earthquake we further assume that this process is repeated in analogy to the reoccurrence of earthquakes on a fault our model assumes that the continental crust behaves elastically below a yield stress y above this stress the continuum deformations can be modeled as a non newtonian viscous flow with y n where n is constant we derive the modified omori s law for aftershock decay using a viscoelastic version of our model and get good agreement with observations taking n 6 using parameter values appropriate for aftershocks we obtain a continuum crustal rheology that can explain major orogenies such as the indian asian collision

acoustic emission experiments of rock failure under load simulating the hypocenter condition a series of acoustic emission ae experiments of rock failure have been conducted under cyclic load in tri axial stress tests to simulate the hypocenter condition the specimens are loaded by the combined action of a constant stress intended to simulate the tectonic loading and a small sinusoidal disturbance stress analogous to the earth tide induced by the sun and the moon each acoustic emission signal can indicate the occurrence time location and relative magnitude of the damage micro crack in the specimen the experimental results verified some precursors such as lurr load unload response ratio and aer accelerating energy release before macro fracture of the samples a new parameter the correlation between the ae and the load has been proposed to describe the loading history on the eve of some strong earthquakes the correlation between the benioff strain and the coulomb failure stress cfs decreases similar to the variation of lurr prior to strong earthquakes

hydrogeology and the bundeswehr water supply to german armed forces in somalia kosovo and afghanistan between 1993 and 2010

precursory seismic activation and critical point phenomena in this paper we relate the behavior of seismicity prior to a characteristic earthquake to the excitation in proximity to a spinodal instability we illustrate the spinodal instability as the upper limit of superheated water prior to a steam explosion we draw an analogy between the steam explosion and a characteristic earthquake and show that the power law activation associated with the spinodal instability is essentially identical to the power law increase in benioff strain observed prior to characteristic earthquakes we find that theory and actual data give very similar results

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

precursory accelerating seismic moment release amr in a synthetic seismicity catalog a preliminary study 1 a power law like acceleration of seismic moment release amr has been proposed as a precursor to large earthquakes because of problems with real world data we have used a synthetic seismicity model of 256 interacting faults embedded in a 3 d elastic half space to search for periods of amr preceding the largest events mw 7 1 in only 5 of 18 cases does the amr model fit the data significantly better than a linear moment release and then only weakly so this proportion or higher occurs in 8 of 1000 randomized catalogs we conclude that either amr is unlikely to be a common precursor or that factors contributing to the amr pattern in the real world are missing from the synthetic model

fiber bundle model for multiscale modeling of hydromechanical triggering of shallow landslides 1 sudden and rapid mass movements associated with landslides and snow avalanches present a hazard to life and infrastructure yet their predictions and triggering mechanisms remain poorly understood statistical methods and correlative studies have been used to produce landslide or avalanche susceptibility maps often with limited physical basis mechanistic approaches based on factor of safety computation seldom represent the progressive transition from local failure events to a landslide and in general do not include heterogeneities associated with land cover or with subsurface material properties and hydrologic pathways focusing on rainfall induced shallow landslides we propose the use of the fiber bundle model fbm a generic yet powerful and adaptable model used in modeling fatigue and fracture of complex and disordered materials the primary strength of the fbm is its ability to represent the progressive failure of cracks and shear zones and the ruptures of highly heterogeneous bonding elements that are present in soils at all scales the model also provides a natural framework for interpretation of acoustic emission signatures from failing slopes which may form the basis of a monitoring and warning system

new observational information on the precursory accelerating and decelerating strain energy release recent reliable data are used to study the behavior of seismic activity before 46 strong shallow earthquakes m 6 0 which correspond to five complete samples of mainshocks these samples include 6 mainshocks m 6 0 7 1 that occurred in western mediterranean since 1980 17 mainshocks m 6 0 7 2 which occurred in the aegean greece and surrounding area since 1980 5 mainshocks m 6 4 7 5 that occurred in anatolia since 1980 12 mainshocks m 6 0 7 3 that occurred in california since 1980 and 6 mainshocks m 7 0 8 3 that occurred in japan since 1990 in all 46 cases a similar precursory seismicity pattern is observed specifically it is observed that accelerating benioff strain square root of seismic energy release caused by preshocks occurs in a broad circular region critical region with a radius about eight times larger than the fault length of the mainshock in agreement with results obtained by various research groups during the last two decades however in a much smaller circular region seismogenic region with a radius about four times the fault length the corresponding preshock strain decelerates with the time to the mainshock the time variation of the strain follows in both cases a power law but the exponent power is smaller than unit m 0 3 in the case of the accelerating preshock strain and larger than unit m 3 0 in the case of the decelerating preshock strain predictive properties of this decelerating in accelerating out strain model are expressed by empirical relations the possibility of using this model for intermediate term earthquake prediction is discussed and the relative model uncertainties are estimated

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

seismicity trends and potential for large earthquakes in the alaska aleutian region the high likelihood of a gap filling thrust earthquake in the alaska subduction zone within this decade is indicated by two independent methods analysis of historic earthquake recurrence data and time to failure analysis applied to recent decades of instrumental data recent may 1993 earthquake activity in the shumagin islands gap is consistent with previous projections of increases in seismic release indicating that this segment along with the alaska peninsula segment is approaching failure based on this pattern of accelerating seismic release we project the occurrence of one or morem 7 3 earthquakes in the shumagin alaska peninsula region during 1994 1996 different segments of the alaska aleutian seismic zone behave differently in the decade or two preceding great earthquakes some showing acceleration of seismic release type a zones while others show deceleration type d zones the largest alaska aleutian earthquakes in 1957 1964 and 1965 originated in zones that exhibit type d behavior type a zones currently showing accelerating release are the shumagin alaska peninsula delarof and kommandorski segments time to failure analysis suggests that the large earthquakes could occur in these latter zones within the next few years

intermediate term earthquake prediction using precursory events in the new madrid seismic zone abstract earthquake prediction may be possible for some mainshock events the time to failure method described by varnes 1989 and bufe and varnes 1990 uses precursory events foreshocks to define an accelerated energy release curve by fitting an equation to the data a predicted time of failure and magnitude can be calculated until recently this method has been used in only a few studies in tectonically active areas and for moderate to large magnitude mainshock events using the microearthquake network data set from the new madrid seismic zone nmsz which is reasonably complete for earthquakes of magnitude 1 5 in the area of interest the method has yielded predicted values of past events as small as m b 3 5 the network data set used in this evaluation covers the time interval from 29 june 1974 to 20 july 1995 for the nmsz there have been 36 earthquakes of magnitude 3 5 over the 21 yr period in which the network has been operating because precursory events are required for the application of the time to failure method mainshocks that occurred before 1980 do not have enough data to adequately define the accelerated energy release curve therefore we utilized the 26 earthquakes that occurred after 1980 and that had a magnitude 3 5 sixteen of the 26 mainshock events were modeled in most cases the precursory sequences yielded predicted times of failure and magnitudes that were reasonably close to the actual mainshock values the remaining mainshocks including those occurring before 1980 could not be modeled due to either 1 not enough events to adequately define the precursory sequence or 2 interfering events that disrupt the accelerated energy release curve in addition two events were modeled from the nuttli catalog nuttli 1979 along with one that used a combination of both catalogs nineteen earthquakes with magnitudes 3 5 were evaluated using the time to failure method the first calculation using the time to failure method gave predicted results with large error bounds essentially no upper bound on the predicted magnitude an empirical relationship between parameters has helped to constrain the range of the predicted magnitude and to a lesser extent the estimated time of failure this relationship modifies the time to failure equation and yields predicted values for magnitudes that have an upper limit another empirical relationship suggests that the logarithm of the moment of the mainshock increases linearly with the logarithm of the size of the precursory event search diameter the relative seismicity of the region also influences the optimum search diameter used to find precursory events in addition to the evaluation of the acceleration sequences associated with the mainshocks an analysis of the occurrence of false positive acceleration sequences acceleration sequences that do not end in a mainshock was conducted the preliminary false positive analysis was conducted by randomly selecting potential mainshock locations the results yielded a false positive acceleration sequence occurrence rate of 2 with the incorporation of the empirical relationships into the time to failure method the potential for future intermediate term earthquake predictions for the nmsz is encouraging

iron sulfide minerals at cement oil field oklahoma implications for magnetic detection of oil fields aeromagnetic anomalies at cement oil field anadarko basin oklahoma have been attributed to authigenic magnetite the following characteristics of the magnetite however indicate that it is contamination introduced by drilling 1 occurrence as sharp angular blades and as spheres commonly with metallographic textures typical of industrial alloys and with associated steel and wustite feo 2 presence only in well cuttings and absence from core and quarry samples and 3 lack of association with detrital framework grains or with authigenic carbonate and sulfide minerals ferrimagnetic pyrrhotite occurs in well cuttings cores and quarry samples at cement and is a possible natural source of the magnetic anomalies pyrrhotite which is intergrown with more abundant fes 2 minerals formed as a result of hydrocarbon seepage pyrrhotite is confined to beds above oil and gas reservoirs these beds which lack detrital organic matter contain higher mineral sulfide and lower mineral sulfate sulfur 1 7 and 0 1 wt respectively than do correlative beds off the field 0 2 and 1 1 wt respectively in the field isotopic values of sulfide s show a systematic decrease upward through the permian section from positive values maximum 12 per mil at 610 760 m depth to negative values 1 to 11 per mil between 32 and 230 m 26 to 30 per mil at the surface geochemical results together with time temperature data derived from burial curves limit the major sources of the sulfide in the fe s minerals to two possibilities isotopically heavy sulfide was generated either inorganically at temperatures 90 c in beds beneath permian beds or by bacterial sulfate reduction at temperatures

predictive modeling of the seismic cycle of the greater san francisco bay region the seismic cycle for the san francisco bay region is synthesized by a model combining the pre and post 1906 seismic histories the long term acceleration of seismic release seismic moment benioff strain release or event count in the seismic cycle and the shorter term accelerations preceding the larger earthquakes within that cycle are modeled using an empirical predictive technique called time to failure analysis in which rate of seismic release is proportional to an inverse power of the remaining time to failure the exponent of time to failure in the accelerating sequences appears to be scale invariant and the length of the full cycle is estimated at 269 50 years the 1989 loma prieta earthquake which is the culmination of the first subcycle in the present long term seismic cycle should have been predictable with an uncertainty of 2 years in time and 0 5 in magnitude although the specific location at loma prieta was not predictable by this technique if our model is correct and if the loma prieta earthquake is the culmination of a subcycle the san francisco bay region should be entering a relatively long 20 50 years period of seismic quiescence above magnitude 6 a great earthquake such as the 1906 san francisco event would appear to be more than a century in the future

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

detecting precursory earthquake migration patterns using the pattern informatics method 1 in this paper we analyze the evolution of seismic activity using a dynamic modification of the pattern informatics method this method identifies locations that have systematic fluctuations in seismicity on pi maps by investigating the evolution of hotspot configurations on the pi map and calculating the distance between hotspots and the epicenter of the impending large earthquake a migrating pattern of increasing or decreasing precursory change in seismicity is revealed we find that hotspots on the pi map appear increasingly closer to the epicenter as the time of the forthcoming earthquake is approached implying the existence of an earthquake preparation process the migration pattern and associated decreasing distance is confirmed by a stochastic test and therefore we conclude that a preparation process prior to large earthquakes can be detected

accelerating seismicity of moderate size earthquakes before the 1999 chi chi taiwan earthquake testing time prediction of the self organizing spinodal model of earthquakes summary seismic activation of moderate size earthquakes for the 1999 chi chi taiwan earthquake has been found a self organizing spinodal sos model can explain some observations concerning seismic activation but the equal time durations of the mid and precursory periods during an earthquake cycle conjectured in the original published sos model have not been supported in this case the chi chi test presented here shows unequal time durations of the mid and precursory periods of an earthquake cycle this in turn makes the possibility of time prediction of a characteristic earthquake impossible in the context of the sos model in addition comparisons with numerical simulations of the sliding block model suggest the change in the system s stiffness is a potential mechanism of seismic activation

frequency of occurrence of moderate to great earthquakes in intracontinental regions implications for changes in stress earthquake prediction and hazards assessments we investigate the departure of shallow intracontinental earthquakes from the frequency magnitude relationship log n m a bm we consider seven large continental regions but exclude subduction zones in each active and stable areas are differentiated within active areas we separately categorize earthquakes on faults with high slip rates we use data sets from 1978 1994 and 1900 1994 which are complete for moment magnitudes mw 5 3 and 7 0 to calculate changes in b value with mw for all active intracontinental regions combined except asia b changes at 98 confidence from 0 90 to 2 1 at a corner magnitude mc of 6 9 to 7 0 the distribution for stable regions indicates a similar change values of mc are associated with downdip widths of rupture of about 23 to 27 km which are smaller than those for subduction zones in each case mc marks a transition from unbounded to bounded earthquakes in asia events from 1958 to 1994 also delineate a similar change near mc 7 0 earthquakes in asia of 7 0 mw 8 1 from 1900 to 1957 however define a b value of 1 0 and a moment release rate 5 6 times higher than that from 1958 to 1994 those anomalous values indicate that a large region of asia was close to failure i e near a self organized critical state during the earlier period we associate those changes with the giant himalayan earthquake in 1950 of mw 8 6 regional variations in seismic strain release rates correlate with the types of processes at adjacent plate boundaries extrapolating rates of activity of the past 95 years to mw 8 0 indicates that such events should be very rare in stable areas

the cyclic and fractal seismic series preceding an mb 4 8 earthquake on 1980 february 14 near the virgin islands summary seismic activity in the 10 months preceding the 1980 february 14 mb 4 8 earthquake in the virgin islands reported on by frankel in 1982 consisted of four principal cycles each cycle began with a relatively large event or series of closely spaced events and the duration of the cycles progressively shortened by a factor of about 3 4 had this regular shortening of the cycles been recognized prior to the earthquake the time of the next episode of seismicity the main shock might have been closely estimated 41 days in advance that this event could be much larger than the previous events is indicated from time to failure analysis of the accelerating rise in released seismic energy using a non linear time and slip predictable foreshock model examination of the timing of all events in the sequence shows an even higher degree of order rates of seismicity measured by consecutive interevent times when plotted on an iteration diagram of a rate versus the succeeding rate form a triangular circulating trajectory the trajectory becomes an ascending helix if extended in a third dimension time this construction reveals additional and precise relations among the time intervals between times of relatively high or relatively low rates of seismic activity including period halving and doubling the set of 666 time intervals between all possible pairs of the 37 recorded events appears to be a fractal the set of time points that define the intervals has a finite non integer correlation dimension of 0 70 in contrast the average correlation dimension of 50 random sequences of 37 events is significantly higher close to 1 0 in a similar analysis the set of distances between pairs of epicentres has a fractal correlation dimension of 1 52 well defined cycles numerous precise ratios among time intervals and a non random temporal fractal dimension suggest that the seismic series is not a random process but rather the product of a deterministic dynamic system