relocation and assessment of seismicity in the iran region summary more than 2000 instrumentally recorded earthquakes occurring in the iran region during the period 1918 2004 have been relocated and reassessed with special attention to focal depth using an advanced technique for 1 d earthquake location a careful review of starting depths association of teleseismic depth phases and the effects of reading errors on these phases are made and when necessary waveforms have been examined to better constrain ehb focal depths uncertainties in ehb epicentres are on the order of 10 15 km in the iran region owing to the earth s lateral heterogeneity and uneven station distribution uncertainties of reviewed ehb focal depth estimates are on the order of 10 km as compared to about 4 km for long period p and sh body waveform inversions nevertheless these ehb depth estimates are sufficiently accurate to resolve robust differences in focal depth distribution throughout the iran region and within their errors show patterns that are in agreement with the smaller number of earthquakes whose depths have been confirmed by body wave modelling or local seismic networks the importance of this result is that future earthquakes with apparently anomalous depths can easily be identified and checked if necessary most earthquakes in the iranian continental lithosphere occur in the upper crust with the crustal shortening produced by continental collision accommodated entirely by thickening and distributed deformation in the zagros mountains nearly all earthquakes are confined to the upper crust depths 20 km and there is no evidence for a seismically active subducted slab dipping ne beneath central iran by contrast in southeastern iran where the arabian seafloor is being subducted beneath the makran coast low level earthquake activity occurs in the upper crust as well as to depths of at least 150 km within a northward dipping subducting slab near the oman line a region transitional between the zagros and the makran seismicity extends to depths of up to 30 45 km in the crust consistent with low angle thrusting of arabian basement beneath central iran in north central iran along the alborz mountain belt seismic activity occurs primarily in the upper crust but with some infrequent events in the lower crust particularly in the western part of the belt the talesh where the south caspian basin underthrusts nw iran earthquakes that occur in a band across the central caspian following the apscheron balkhan sill between azerbaijan and turkmenistan have depths in the range 30 100 km deepening northwards these are thought to be connected with either incipient or remnant northeast subduction of the south caspian basin basement beneath the east west trending apscheron balkhan sill curiously in this region of genuine mantle seismicity there is no evidence for earthquakes shallower than 30 km

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

application of stress release models to historical earthquakes from north china univariate and multivariate stress release models are fitted to historical earthquake data from north china it is shown that a better fit is obtained by treating separately the eastern part of the region including the north china plain and bohai sea and the western part of the region including the ordos plateau and its eastern boundary further improvement is obtained by fitting the large events m 7 6 and smaller events in the western region by different stress release models the comparisons are made by computing the likelihoods of the fitted models and discounting the number of parameters used by akaike s aic criterion the models are used to develop long term risk scenarios for the east and west regions

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

earthquake size as a function of fault slip rate abstract estimates of the potential size of earthquakes on mapped active faults are generally based on regressions of earthquake magnitude m w versus length l of fault rupture for historical earthqukes the fault slip rate s has been ignored in formal prediction equations but more accurate predictions of future earthquake magnitudes on mapped faults may be obtained when it is included a least squares regression for a data set of 43 earthquakes occurring on faults for which slip rates are reported shows m w 5 12 1 16 log l 0 20 log s where l is in units of km and s is in units of mm yr the result indicates that the largest earthquakes will occur on the slowest slipping faults if the rupture length is held constant

seismic moment distribution revisited i statistical results summary an accumulation of seismic moment data gathered over the previous decade justifies a new attempt at a comprehensive statistical analysis of these data herein more rigourous statistical techniques are introduced their properties investigated and these methods are employed for analysis of large modern data sets several theoretical distributions of earthquake size seismic moment frequency relations are described and compared we discuss the requirements for such distributions and introduce an upper bound or a corner moment for a distribution to have a finite energy or moment flux we derive expressions for probability density functions and statistical moments of the distributions we also describe parameter evaluation in particular how to estimate the seismic moment distribution for the largest earthquakes simulating earthquake size distributions allows for a more rigourous evaluation of distribution parameters and points to the limitations of the classical statistical analysis of earthquake data simulations suggest that several earthquakes approaching or exceeding the corner magnitude mc limit need to be registered to evaluate mc with reasonable accuracy using the harvard catalogue data we compare moment distribution parameters for various temporal spans of the catalogue for different tectonic provinces and depth ranges and for earthquakes with various focal mechanisms the statistical analysis suggests that the exponent b is universal b 0 60 0 65 for all moderate earthquakes the corner moment mc value determined by the maximum likelihood method both in subduction zones and globally is about 10 21 n m corresponding to the corner moment magnitude mc 8 0 for midoceanic earthquakes mc is apparently smaller for spreading ridges it is about 5 8 and for strike slip earthquakes on transform faults it decreases from 7 2 to 6 5 as the relative slip velocity of faults increases we investigate the seismic moment errors both random and systematic and their dependence on earthquake size the relative errors seem to decrease for larger events the influence of moment uncertainties on the parameter estimates is studied whereas the b values do not appear to be significantly influenced by the errors for the corner moment large errors can lead to substantially biased estimates we compare the harvard catalogue results with the earthquake data from instrumental catalogues in the first three quarters of the 20th century several very large earthquakes mi9 occurred around the middle of the century their magnitude values cannot be fitted by a modified gutenberg richter law with mc 8 0 8 5 among other factors this discrepancy can be explained by either substantially higher errors in the earlier magnitude values or by mc being higher for some subduction zones it is unlikely that data available presently or soon will be sufficient to determine the corner magnitude of 9 and above with reasonable precision using purely statistical methods

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

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

estimation of earthquake hazard parameters from incomplete data files part iii incorporation of uncertainty of earthquake occurrence model most probabilistic seismic hazard analysis procedures require that at least three seismic source parameters be known namely the mean seismic activity rate the gutenberg richter b value and the area characteristic seismogenic source maximum possible earthquake magnitude m max in almost all currently used seismic hazard assessment procedures that utilize these three parameters it is explicitly assumed that all three remain constant over time and space however closer examination of most earthquake catalogs has indicated that significant spatial and temporal variations existed in the seismic activity rate as well as in the gutenberg richter b value in this study the maximum likelihood estimation of these earthquake hazard parameters considers the incompleteness of the catalogs the uncertainty in the earthquake magnitude determination as well as the uncertainty associated with the applied earthquake occurrence models the uncertainty in the earthquake occurrence models is introduced by assuming that both the mean seismic activity rate and the gutenberg richter b value are random variables each described by the gamma distribution this approach results in the extension of the classic frequency magnitude gutenberg richter relation and the poisson distribution of the number of earthquakes with their compounded counterparts benjamin 1968 campbell 1982 1983 the proposed procedure was applied in the estimation of the seismicity parameters in an area that had experienced the strongest and most devastating earthquake in contemporary south african history namely the 29 september 1969 m w 6 3 ceres tulbagh event in this example it was shown that the introduction of uncertainty in the earthquake occurrence model reduced the mean return periods leading to an increase of the estimated seismic hazard additionally this study confirmed that accounting for magnitude uncertainties had the opposite effect that is it brought about increases in the return periods or equivalently a reduction of the estimated seismic hazard

a new insight into probabilistic seismic hazard analysis for central india the son narmada tapti lineament and its surroundings of central india ci is the second most important tectonic regime following the converging margin along himalayas myanmar andaman of the indian sub continent which attracted several geoscientists to assess its seismic hazard potential our study area a part of ci is bounded between latitudes 18 26 n and longitudes 73 83 e representing a stable part of peninsular india past damaging moderate magnitude earthquakes as well as continuing microseismicity in the area provided enough data for seismological study our estimates based on regional gutenberg richter relationship showed lower b values i e between 0 68 and 0 76 from the average for the study area the probabilistic seismic hazard analysis carried out over the area with a radius of 300 km encircling bhopal yielded a conspicuous relationship between earthquake return period t and peak ground acceleration pga analyses of t and pga shows that pga value at bedrock varies from 0 08 to 0 15 g for 10 t 475 years and 2 t 2 475 years probabilities exceeding 50 years respectively we establish the empirical relationships text zpa t 475 0 1146 v text s 30 0 2924 and text zpa t 2475 0 2053 v text s 30 0 2426 between zero period acceleration zpa and shear wave velocity up to a depth of 30 m v s 30 for the two different return periods these demonstrate that the zpa values decrease with increasing shear wave velocity suggesting a diagnostic indicator for designing the structures at a specific site of interest the predictive designed response spectra generated at a site for periods up to 4 0 s at 10 and 2 probability of exceedance of ground motion for 50 years can be used for designing duration dependent structures of variable vertical dimension we infer that this concept of assimilating uniform hazard response spectra and predictive design at 10 and 2 probability of exceedance in 50 years at 5 damping at bedrocks of different categories may offer potential inputs for designing earthquake resistant structures of variable dimensions for the ci region under the national earthquake hazard reduction program for india

hydraulic conductivity of geosynthetic clay liners exhumed from landfill final covers samples of geosynthetic clay liners gcls from four landfill covers were tested for water content swell index hydraulic conductivity and exchangeable cations exchange of ca and mg for na occurred in all of the exhumed gcls and the bentonite had a swell index similar to that for ca or mg bentonite hydraulic conductivities of the gcls varied over 5 orders of magnitude regardless of cover soil thickness or presence of a geomembrane hydraulic conductivity was strongly related to the water content at the time of sampling controlled desiccation and rehydration of exhumed gcls that had low hydraulic conductivity 10 9 to 10 7 cm s resulted in increases in hydraulic conductivity of 1 5 4 orders of magnitude even with overburden pressure simulating a 1 m thick cover comparison of these data with other data from the united states and europe indicates that exchange of ca and or mg for na is likely to occur in the field unless the overlying cover soil is sodic sodium rich the comparison also shows th

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

origin of sheet structure 1 morphology and boundary conditions abstract sheet structure or large scale exfoliation is the division of a rock mass into lenses plates or sheets approximately parallel to the earth s surface sheet fractures which separate the plates are characterized by surface markings resembling those formed during the brittle fracture of metals glass and ceramics and those on joints in rock lineations or hackle marks parallel to the direction of fracture propagation are common branching occurs during propagation so that the fractures appear as many echelon segments in profile the opposing surfaces of sheet fractures observed in quarry walls and natural exposures are typically in contact damage if any to rock adjacent to sheet fractures is generally limited to a zone less than one centimeter wide sheets tend to parallel preferred orientations of microcracks in many rock masses most sheets that are exposed today are of prehistoric origin but in some rock masses such as chelmsford granite in massachusetts new sheets continue to form sheet structure forms in environments of high differential stress dominated by large scale compression parallel to an exposed rock surface in parts of the chelmsford granite the magnitude of this compression is greater than 30 mpa in the zone of sheeting high differential stresses near the ground surface can result from several natural agents including contemporary tectonic forces vertical unloading of a rock mass that formed at depth under high triaxial compression and suppression of expansion that would otherwise result from temperature increases or chemical alteration of the rock exfoliation of boulders during forest fires and spheroidal weathering of boulders appears to occur under similar states of stress although the agents responsible for the stresses differ

evolution of stress deficit and changing rates of seismicity in cellular automaton models of earthquake faults we investigate the internal dynamics of two cellular automaton models with heterogeneous strength fields and differing nearest neighbour laws one model is a crack like automaton transferring all stress from a rupture zone to the surroundings the other automaton is a partial stress drop automaton transferring only a fraction of the stress within a rupture zone to the surroundings to study evolution of stress the mean spectral density cal s k r of a stress deficit field is examined prior to and immediately following ruptures in both models both models display a power law relationship between cal s k r and spatial wavenumber k r of the form cal s k r sim k beta r in the crack model the evolution of stress deficit is consistent with cyclic approach to and retreat from a critical state in which large events occur the approach to criticality is driven by tectonic loading short range stress transfer in the model does not affect the approach to criticality of broad regions in the model the evolution of stress deficit in the partial stress drop model is consistent with small fluctuations about a mean state of high stress behaviour indicative of a self organised critical system despite statistics similar to natural earthquakes these simplified models lack a physical basis physically motivated models of earthquakes also display dynamical complexity similar to that of a critical point system studies of dynamical complexity in physical models of earthquakes may lead to advancement towards a physical theory for earthquakes

near source attenuation of peak horizontal acceleration strong motion data recorded within 50 km of the rupture zone were used to study near source attenuation characteristics of horizontal peak ground acceleration for worldwide earthquakes of magnitudes 5 0 to 7 7 the data base consisted of 229 horizontal components of peak acceleration recorded from 27 earthquakes including the 15 october 1979 imperial valley earthquake these data were found to be adequately represented by the functional relationship pga a exp b m r c m d where pga represents the mean of the peak values scaled from the two horizontal components of each recording m is richter magnitude and r is distance from the fault rupture zone peak acceleration was found to be lognormally distributed with a standard error representing a 45 per cent increase in the median estimate the regression analysis statistically confirmed the results of earthquake simulation studies that have predicted peak acceleration to become independent of magnitude and distance in the near field an extensive sensitivity study showed that predictions based on our attenuation relationships are stable with respect to reasonable model and parameter variations an analysis of residuals was used to investigate the behavior of peak acceleration with respect to various earthquake site and recording parameters the more significant findings being 1 a similarity in the level of acceleration recorded on soil or rock 2 larger than average accelerations recorded at sites located on shallow soils or in areas of steep topography 3 larger than average accelerations associated with earthquakes having reverse fault mechanisms and 4 lower than average accelerations recorded in large embedded structures

a seismic hazard map of india and adjacent areas abstract we have produced a probabilistic seismic hazard map showing peak ground accelerations in rock for india and neighboring areas having a 10 probability of being exceeded in 50 years seismogenic zones were identified on the basis of historical seismicity seismotectonics and geology of the region procedures for reducing the incompleteness of earthquake catalogs were followed before estimating recurrence parameters an eastern united states acceleration attenuation relationship was employed after it was found that intensity attenuation for the indian region and the eastern united states was similar the largest probabilistic accelerations are obtained in the seismotectonic belts of kirthar hindukush himalaya arakan yoma and the shillong massif where values of over 70 g have been calculated

the preservation of seismic anisotropy in the earth s mantle during diffusion creep summary seismic anisotropy in the earth particularly in the mantle is commonly interpreted as the result of solid state deformation by dislocation creep that induces a lattice preferred orientation lpo diffusion creep operates where stress levels are lower and or grain sizes smaller it is often assumed that diffusion creep induces grain rotations that eventually destroy any existing lpo a new numerical test of this assumption shows that it is not necessarily the case diffusion creep will create some relative grain rotations but rotation rates decrease through time hence when microstructural change due to diffusion creep dominates that due to grain growth defined here as type p behaviour the converse being type o behaviour the model indicates that lpo will be weakened but preserved for a variety of strain paths including both pure and simple shear one measure of anisotropy is the proportional difference in shear wave velocities for different polarization vectors avs a model olivine microstructure with equant grains and initial maximum avs of 10 0 percent has this value reduced to 6 7 per cent when rotational steady state is attained other models with different initial maximum avs values exhibit final maximum avs values more than half the initial values if the grains are initially elongate by a factor of 2 maximum avs is reduced just slightly to 8 5 per cent thus when grain growth plays a subordinate role to the deformation diffusion creep weakens seismic anisotropy by a factor of less than 2 using maximum avs as a measure and olivine as an example consequently the link between seismic anisotropy and deformation mechanism in the mantle requires reappraisal regions with lpo may comprise material which once deformed by dislocation creep but is now deforming by diffusion creep in a rotational steady state

quantifying seismicity parameter uncertainties and their effects on probabilistic seismic hazard analysis a case study of iran probabilistic seismic hazard analysis psha can accommodate various sources of uncertainties and it provides a rational framework for the precise portrayal of the hazard of a given region often the information used in the psha is incomplete and uncertain therefore the question arises how the uncertainty of the input data affects the estimated hazard characteristics in this study sensitivity analysis sa was conducted to identify the most dominant inputs affecting the assessment of the key seismicity parameters sps including the mean seismic activity rate b value of gutenberg richter and the maximum possible earthquake magnitude m hbox max the study was applied in five areas of iran for which such analyses have not been conducted in previous studies subsequently monte carlo simulation was employed to determine the effects of the uncertain input parameters on psha relevant to spectral accelerations corresponding to 10 and 2 probability of exceedance at least once in 50 years for this purpose a unified and declustered earthquake catalogue was used for the five major seismotectonic provinces of iran alborz azarbayejan zagros central east iran koppeh dagh and makran the results showed that the last complete part of the catalogue has a significant effect on the estimated value of seismic activity and the b value in contrast its influence is insignificant on the area characteristic maximum possible earthquake magnitude for which the most influential inputs are the maximum observed earthquake and its uncertainty furthermore the uncertainties of the input sps affected the seismic hazard estimates substantially and led to significant variability in the estimated ground motion characteristics

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

a note on falling head and rising tail permeability tests on saturated soils in centrifuge the falling head and rising tail method for permeability test allows for both inflow and outflow rates to be conveniently measured this helps to detect any possible swelling or consolidation of sp

application of the stress release model to the nankai earthquake sequence southwest japan abstract the stress release model was applied to the nankai earthquakes which occurred in an area off the kii peninsula and shikoku island in the southwest of japan these are considered to be inter plate earthquakes the result of relative movement between the eurasian and the philippine sea plates the dates and sizes of earlier events were determined from historical documents recurrence intervals of the earthquakes were distributed in a range from around 90 to 210 years the stress release model attempts to provide a general formulation of the idea of the elastic rebound theory the hazard rate of the model is given in the form of exp a0 b0t c0s t where a0 b0 and c0 are the parameters adjusted to the data the function of s t corresponds to the stress released by the events up to time t the adjusted parameters are estimated through the optimization of the likelihood function by using the akaike information criterion aic the stress release model is compared with models based on a renewal process several cases were studied using subsets of the sequence the best example of the stress release model in comparison with renewal models is observed in the case of the eight most recent events this model evaluates the timing of the next event in later years and in a narrower time range than those obtained from the renewal models

accuracy of modern global earthquake catalogs we compare several modem 1977 present worldwide earthquake catalogs to infer their completeness earthquake origin time and hypocenter location accuracy magnitude scalar seismic moment errors and difference between individual focal mechanism moment tensor solutions the harvard centroid moment tensor cmt us geological survey usgs mt usgs first motion fm focal mechanism pde and isc catalogs have been analyzed and compared the catalogs completeness and accuracy vary in time and depend on earthquake depth and tectonic environment we propose a new statistical method for evaluating catalog completeness and show the results for the cmt dataset a difference in frequency range of seismic waves used in earthquake processing leads to varying degrees of catalog completeness for foreshocks and aftershocks close in time earthquake origin time versus centroid time as well as hypocenter location versus centroid location can be explained well by earthquake scaling relations comparing moment magnitudes and regular earthquake magnitudes yields estimated magnitude uncertainties and shows that latter magnitudes poorly estimate earthquake size for large events moment errors reported in the cmt solutions are well correlated with the cmt gs mt magnitude difference and hence indicate magnitude uncertainty well a normalized seismic moment tensor has 4 d f and its accuracy can be represented as the non double couple non dc component value the 3 d angle phi of dc source rotation and a position of the rotation pole our results suggest that a routinely determined non dc component is in most cases only an artifact the distribution of the phi value varies over catalog time earthquake depth focal mechanism and magnitude the seismic moment errors and the value of the non dc component are indicative of the phi value for the best solutions the 3 d angle in the cmt catalog is on the order of 5 7degrees the cmt catalog is obviously the best dataset in completeness and accuracy of its detailed solutions our results specifying uncertainties and completeness of global earthquake catalogs can be used in studies of geodynamic processes tectonic deformation associated with earthquakes earthquake stress analysis and in many other applications of earthquake catalog data seismogram interpretation techniques can be reviewed and possibly revised in light of these results c 2002 elsevier science b v all rights reserved

chemical signature detection of groundwater and geothermal waters for evidence of crustal deformation along fault zones abstract common crustal igneous and high grade metamorphic rocks contain peroxy defects which remain dormant until the rock experiences stress upon deformation stress activated peroxy defects form highly reactive oxygen species ros at the rock water interface observed in both terrestrial and extraterrestrial rock samples the ros complex is formed upon rock fluid interaction when groundwater combines with the ros to produce hydrogen peroxide giving an indirect measure of the underlying rock stress and crustal deformation along active faults the average concentration of hydrogen peroxide from the sohna thermal spring water falling along the active sohna fault and geothermal field was measured to be 0 53 0 014 mg l similar average concentration was also recorded from borewell sample north of the spring 0 56 0 017 mg l within the same geothermal field lower concentration of hydrogen peroxide was recorded within samples collected from hard rock aquifers outside the geothermal field and the active fault zone 0 138 0 095 mg l the detailed analysis suggests that the presence of hydrogen peroxide is largely dependent on the circulation pattern through the interconnected fractures joints within the quartzite bedrock lying adjacent to the fault plane laboratory analysis results also show high hydrogen peroxide concentration within two borewell samples falling adjacent to the epicentre of a shallow microtremor event within the hard rock region falling alongside a lineament along the delhi hard rock mega fold rock water interaction post stress activation of peroxy defects and formation of ros has therefore been inferred to be responsible for the formation of hydrogen peroxide at the rock water interface within these zones this pilot study provides scientific field evidence that hydrogen peroxide concentrations within groundwaters might offer prospects for seismic stress estimation and crustal deformation along seismically active zones

reassessment of earthquakes 1900 1999 in the eastern mediterranean and the middle east summary we have reappraised locations and surface wave magnitudes of earthquakes this century in the eastern mediterranean and the middle east between 10 and 44 n and 18 and 70 e the results are presented in an improved parametric catalogue of shallow earthquakes h 40 km large enough ms 6 0 to be of interest in seismotectonics and earthquake engineering a considerable number of early events of 6 ms 7 2 not included in other catalogues have been identified and their magnitudes assessed we find that iss isc locations are systematically shifted by 10 30 km to the north or northeast of their macroseismic epicentres also we derived a regional average relationship between log m0 and ms we show that the correlation of magnitude with epicentral intensity is very weak as is expected and a source of error in frequency relations

probabilistic appraisal of earthquake hazard parameters deduced from a bayesian approach in the northwest frontier of the himalayas a straightforward bayesian statistic is applied in five broad seismogenic source zones of the northwest frontier of the himalayas to estimate the earthquake hazard parameters maximum regional magnitude mmax value of g r relationship and seismic activity rate or intensity for this purpose a reliable earthquake catalogue which is homogeneous for mw 5 0 and complete during the period 1900 to 2010 is compiled the hindukush pamir himalaya zone has been further divided into two seismic zones of shallow h 70 km and intermediate depth h 70 km according to the variation of seismicity with depth in the subduction zone the estimated earthquake hazard parameters by bayesian approach are more stable and reliable with low standard deviations than other approaches but the technique is more time consuming in this study quantiles of functions of distributions of true and apparent magnitudes for future time intervals of 5 10 20 50 and 100 years are calculated with confidence limits for probability levels of 50 70 and 90 in all seismogenic source zones the zones of estimated mmax greater than 8 0 are related to the sulaiman kirthar ranges hindukush pamir himalaya and himalayan frontal thrusts belt suggesting more seismically hazardous regions in the examined area the lowest value of mmax 6 44 has been calculated in northern pakistan and hazara syntaxis zone which have estimated lowest activity rate 0 0023 events day as compared to other zones the himalayan frontal thrusts belt exhibits higher earthquake magnitude 8 01 in next 100 years with 90 probability level as compared to other zones which reveals that this zone is more vulnerable to occurrence of a great earthquake the obtained results in this study are directly useful for the probabilistic seismic hazard assessment in the examined region of himalaya

heterogeneity and the earthquake magnitude frequency distribution regional earthquake populations are widely observed to have power law magnitude frequency statistics whether earthquake distributions on individual faults are similarly power law is presently the subject of considerable research effort recent careful observations suggest that event statistics on rough faults are power law whereas earthquake distributions on smooth faults are better described by a characteristic model in which there are more large earthquakes than would be expected by extrapolation from the distribution of small events here the relation between heterogeneity and the magnitude frequency distribution is investigated in a cellular automaton that includes new nearest neighbor stress transfer rules which produce realistic stress concentrations the results agree with the suggestion that smooth faults have more characteristic earthquake distributions and support the view that an earthquake s size is controlled by rupture arrest

patterns of historical earthquake rupture in the iranian plateau the iranian plateau accommodates the 35 mrn yr convergence rate be tween the eurasian and arabian plates by strike slip and reverse faults with relatively low slip rates in a zone 1000 km across although these faults have only locally been the subject of paleoseismological studies a rich historical and archeological record spans several thousand years long enough to establish recurrence intervals of 1000 to 5000 yr on individual fault segments several clusters of earthquakes provide evidence of interaction among reverse and strike slip faults probably due to adjacent faults being loaded by individual earthquakes the dasht e bayaz sequence of 1936 to 1997 includes earthquakes on left lateral right lateral and reverse faults the neyshabur sequence of four earthquakes between 1209 and 1405 respected the seg ment boundary between the neyshabur and binalud reverse fault systems the two pairs of earthquakes may have ruptured different faults in each segment similar to the 1971 and 1994 san fernando california earthquakes the 1978 tabas reverse fault earthquake was preceded by the 1968 ferdows earthquake part of the dasht e bayaz sequence the north tabriz fault system ruptured from southeast to north west in three earthquakes from 1721 to 1786 a previous cluster may have struck this region in 855 to 958 the mosha fault north of tehran ruptured in three earthquakes in 958 1665 and 1830 five large earthquakes struck the tehran region from 743 to 1177 but only two that large have struck the area since 1177 other earthquakes occurred in pairs in the talesh mountains near the caspian sea 1863 1896 the iran turkey border 1840 1843 and the nayband gowk fault system both 1981 other historical events did not occur as parts of sequences the historic seismic moment release in iran accounts for only a small part of the plate convergence rate which may be due to aseismic slip or to the iranian historical record long as it is being too short to sample long term deformation across the plateau no historic earthquakes of m 8 have struck iran however several long straight strike slip faults doruneh west neh east neh and nayband have not sustained large historical earthquakes raising the possibility that these long faults could produce earthquakes of m 8 thereby removing at least part of the apparent slip deficit an increased understanding of iran s seismic hazard could be obtained by an extensive paleoseismology program and space geodetic arrays supplementing the abundant historical and archaeological record

hydraulic conductivity of bentonite slurry mixed sands the hydraulic conductivity k of specimens from columns containing initially dry sands mixed with bentonite slurries was measured the mixed specimens represented a range in void ratios 0 672 e 3 94 and bentonite contents 0 61 bc 7 65 by dry weight the measured k values which ranged from 2 4 10 7 cm s to 6 8 10 4 cm s correlated poorly with the total void ratio e of the specimens due to the complicating effect of the bentonite in the sand bentonite slurry mixtures however the measured k values correlated better with the void ratio of the bentonite eb which is consistent with the results of previous studies involving permeation of compacted bentonite and sand bentonite specimens even though the range in values of eb in this study 42 5 eb 127 was much higher than that previously reported the relatively large range in eb values for the sand bentonite slurry mixtures was also consistent with the relatively large range in measured k values which are about one to seven or

estimating earthquake hazard parameters from instrumental data for different regions in and around turkey abstract we conducted a study of the spatial distributions of seismicity and earthquake hazard parameters for turkey and the adjacent areas applying the maximum likelihood method the procedure allows for the use of either historical or instrumental data or even a combination of the two by using this method we can estimate the earthquake hazard parameters which include the maximum regional magnitude m max the activity rate of seismic events and the well known b value which is the slope of the frequency magnitude gutenberg richter relationship these three parameters are determined simultaneously using an iterative scheme the uncertainty in the determination of the magnitudes was also taken into consideration the return periods rp of earthquakes with a magnitude m m are also evaluated the whole examined area is divided into 24 seismic regions based on their seismotectonic regime the homogeneity of the magnitudes is an essential factor in such studies in order to achieve homogeneity of the magnitudes formulas that convert any magnitude to an m s surface scale are developed new completeness cutoffs and their corresponding time intervals are also assessed for each of the 24 seismic regions each of the obtained parameters is distributed into its respective seismic region allowing for an analysis of the localized seismicity parameters and a representation of their regional variation on a map the earthquake hazard level is also calculated as a function of the form m max rp 6 0 and a relative hazard scale defined as the index k is defined for each seismic region the investigated regions are then classified into five groups using these parameters this classification is useful for theoretical and practical reasons and provides a picture of quantitative seismicity an attempt is then made to relate these values to the local tectonics

the determination of earthquake hazard parameters deduced from bayesian approach for different seismic source regions of western anatolia the bayesian method is used to evaluate earthquake hazard parameters of maximum regional magnitude mmax value and seismic activity rate or intensity and their uncertainties for the 15 different source regions in western anatolia a compiled earthquake catalog that is homogenous for ms 4 was completed during the period from 1900 to 2013 the computed mmax values are between 6 00 and 8 06 low values are found in the northern part of western anatolia whereas high values are observed in the southern part of western anatolia related to the aegean subduction zone the largest value is computed in region 10 comprising the aegean islands the quantiles of functions of distributions of true and apparent magnitude on a given time interval 0 t are evaluated the quantiles of functions of distributions of apparent and true magnitudes for future time intervals of 5 10 20 50 and 100 years are calculated in all seismogenic source regions for confidence limits of probability levels of 50 70 and 90 according to the computed earthquake hazard parameters the requirement leads to the earthquake estimation of the parameters referred to as the most seismically active regions of western anatolia the aegean islands which have the highest earthquake magnitude 7 65 in the next 100 years with a 90 probability level is the most dangerous region compared to other regions the results found in this study can be used in probabilistic seismic hazard studies of western anatolia

long term seismicity behavior of the zagros region in iran to achieve a comprehensive attitude about seismicity it is necessary to consider spatial and magnitude distributions of earthquakes earthquake distributions in space and magnitude can be quantified by means of spatial fractal dimension d s and gutenberg richter b value in this paper b value and d s are used to evaluate seismicity of the zagros zone iran in time interval 1964 to 2012 seismic catalog of the zagros zone is extracted from unified seismic catalog of the iranian plateau the b value and d s are estimated using frequency magnitude distribution kijko sellevoll bull seism soc am 79 3 645 654 1989 and correlation integral methods correlations between spatial variations in b value and d s along individual profiles across the north zagros and the central zagros indicate different stress release regimes for north and central parts of the zagros zone evaluation of b value with respect to depth along the profiles indicates larger b values at shallower depths temporal variations in b value and d s are also obtained from background seismicity to evaluate seismicity behavior of the zagros zone our results indicate high b values and moderate d s for seismicity of the north zagros while seismicity of the central zagros has low b values and high d s during time interval 1964 2012 asperities of the main zagros thrust are also located by investigating ratio d s b along the main zagros thrust

timing of tectonic events in the menderes massif western turkey implications for tectonic evolution and evidence for pan african basement in turkey the menderes massif forms the western of the two large metamorphic culminations within the turkish alpide orogen it has three major lithologic units with a gneissic core at the base and a schist and a marble envelope overlying it successively although relations between them have been largely obscured by the polymetamorphic and structurally complex history of the massif we present a review of the available stratigraphic evidence and combine it with new isotopic ages from the central and southern parts of the massif to constrain the timing of major tectonic events that shaped the massif since the late proterozoic pt3 in the southern part of the massif sensu stricto three episodes of deformation and metamorphism are distinguished whereas in its northern part there are four the first episode occurred at 500 10 ma with intense deformation and metamorphism at high grade amphibolite facies with local anatexis in the central part of the massif the 470 9 ma old now highly deformed tonalitic and granitic intrusions mark the end of this episode on a cambrian reconstruction of continents around the eastern mediterranean the menderes massif forms the southern end of the pan african orogenic collage of northeastern africa and arabia the area of earliest palaeozoic deformation in the menderes may connect with the northwest african orogenic collage along the strike via the bozburun and saricicek diabases arkoses and schists in the center of the karacahisar dome interpreted herein as fragments of a pan african suture the earliest palaeozoic deformations to affect the rocks were probably related to the last pan african collisions and associated postcollisional convergence the southern part of the massif was undeformed from early ordovician to the early later eocene whereas the northern part was deformed metamorphosed and intruded possibly during the late triassic related to the closure of the karakaya marginal basin of palaeo tethys the next major event affecting the whole of the massif was the intense deformation and widespread metamorphism that reached high amphibolite grade in the structurally lower parts and only greenschist grade in the outermost envelope this metamorphism here called the main menderes metamorphism mmm is biostratigraphically constrained between early eocene and early oligocene time rb sr isotopic data show a spread of ages between 60 ma and 25 ma with the greatest number of determinations around 35 5 ma this number is in excellent agreement with the stratigraphic evidence and shows that mmm took place during latest eocene time or at the transition from eocene to oligocene time along the northern border of the massif deformation and metamorphism had already taken place during the late cretaceous in a high pressure low temperature hp lt metamorphic belt northernmost part of menderes massif sensu lato which was then covered by palaeocene molasse the evolution of the hp lt belt was probably related to the obduction of the bozkir ophiolites from the izmir ankara branch of the neo tethys ocean and preceded terminal collision in the evolution of the massif the mmm was a product of the latest palaeocene collision across neo tethys and the consequent internal imbrication of the menderes taurus block that resulted in the burial of the menderes massif area beneath the lycian nappe complex a low grade metamorphic event dated at 10 to 5 ma is interpreted to be related to the extensional deformation in the aegean and western turkey which has been dated stratigraphically to have begun during the tortonian 11 5 ma

temporal variations of seismic parameters in tehran region the study of earthquake precursors can lead to deliver an entirely measurable time varying estimation of the coming events which is strongly based on physical and geological principals and fully responsive to any future examination the temporal variation of the seismic parameters such as b values in the gutenberg richter formula logn a bm some details of the pre shock accelerating moment release amr and the variation of the thirumalai and mountain tm metric before the past big event is investigated in the vicinity of the tehran city the temporal variation of the b value in some cases strongly supports the assumption that it has potential to be used as a precursory signal in addition analysis of the pre shock amr along with the inverse tm metric signal in the region shows deviations from the background long term behavior prior to some of the bigger events in the studied area the aggregation of these signs suggests that a combination of studied physical precursors has a potential which could be employed in a medium term earthquake warnings

morphological impacts of low magnitude seismic events on granite viewing certain landforms with new eyes abstract several landforms developed in massive brittle rocks located in cratonic settings and formerly thought to be caused by external agencies are now attributed to low magnitude seismic events or earth tremors field observations and particularly monitoring of specific sites have shown that the frequent joggling of shield areas has given rise to miniature scarps that define dislodged segments furthermore sheeting fractures previously well known as offloading joints are planes of dislocation and are initiated during low energy earthquakes a tents or pop ups were in past times widely attributed to insolation and less commonly to offloading but they too and like sheet structures and rock wedges are formed by compressive stress applied either instantly during earth tremors or gradually over decades many of these forms develop after exposure but some a tents are almost certainly initiated at the weathering front wedges also develop in the subsurface rock bursts and slabs and blocks are displaced or split during earth tremors it is not suggested that lithostatic pressure can be overlooked but applied compression as well as reduced lithostatic loading are necessary for the development of sheet fractures and the other forms cited

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

late cenozoic volcanic evolution of the northeastern aegean region abstract late cenozoic volcanism occurred in an extensional tectonic regime in the northeastern aegean activity commenced in northeastern greece during the early oligocene and in northwestern turkey during the late oligocene early miocene the beginning of activity was characterized by calc alkaline intermediate acid volcanism however alkaline intermediate basic volcanism became dominant from the late miocene until the pleistocene this change in nature of volcanism is not related to a change of regional tectonic regime as previously thought instead we propose that the volcanic evolution reflects an increasing asthenospheric contribution facilitated by a thinned extended lithosphere arising from the regional extensional tectonics

permeation of sand processed clay mixtures with calcium chloride solutions the hypothesis that the substitution of attapulgite clay for bentonite in an otherwise sand bentonite s b mixture will improve the resistance to change in hydraulic conductivity of the mixture upon permeation with calcium chloride cacl d2 solutions relative to permeation with a processed tap water is tested for mixtures with the same clay soil content complete substitution of attapulgite clay for bentonite significantly decreases the change in hydraulic conductivity relative to that observed for the s b mixtures upon permeation with a 0 5 m cacl d2 solution in addition the resistance to change in hydraulic conductivity of the sand attapulgite clay bentonite s ac b mixtures containing 20 clay soil is improved by increasing the percentage of attapulgite clay in the clay soil admixture from 50 to 100 and by decreasing the concentration of the cacl d2 solution from 0 5 m to 0 the first exposure effect also decreases with increasing amount of attapulgite clay in s ac b mixtures containing 20 clay soil however the resistance to change in hydraulic conductivity resulting from substituting only half of the bentonite in the s b mixtures with an equal amount of attapulgite clay is not improved substantially due to the dominating influence of the bentonite portion of the sand clay mixture

quantitative analysis of seismicity in iran we use historical and recent major earthquakes and gps geodetic data to compute seismic strain rate geodetic slip deficit static stress drop the parameters of the magnitude frequency distribution and geodetic strain rate in the iranian plateau to identify seismically mature fault segments and regions our analysis suggests that 11 fault segments are in the mature stage of the earthquake cycle with the possibility of generating major earthquakes these faults primarily are located in the north and the east of iran four seismically mature regions in southern iran with the potential for damaging strong earthquakes are also identified we also delineate four additional fault segments in iran that can generate major earthquakes without robust clues to their maturity the most important fault segment in this study is the strike slip system near the capital city of tehran with the potential to cause more than one million fatalities

further applications of the stochastic stress release model to historical earthquake data abstract the stochastic stress release model provides a stochastic version of the elastic rebound model which may be used to fit simulate and forecast occurrence of large earthquakes within a seismic region this paper reviews its applications to historical earthquakes from china iran and japan thereby extending and supporting earlier work on the chinese historical data the model generally provides an improvement in fit over poisson models with either constant rate or linear trend a crucial factor is the identification of suitable subregions which can act as largely independent seismic units in northern china divisions into two and four such units are considered based on recognized geophysical subdivisions in iran the best results are obtained from a subdivision into three such units the situation in japan seems more complex a preliminary model with two units gives a significant improvement of fit in one out of the two cases in all regions treating the subregions separately gives marked improvements over treating the whole region as a single unit however the quality of fit within subregions differs sharply from case to case pointing to substantial differences in the seismic regimes as reflected in the historical data

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

seismic zonation of the delhi region for bedrock ground motion an endeavor is made to compute peak ground horizontal accelerations at bedrock level in the delhi region due to the seismogenic sources present around delhi the entire area is divided into six seismogenic sources for which seismic hazard analysis is carried out using the complete and extreme part of the seismicity data maximum likelihood estimates of hazard parameters viz seismic activity rate b value and maximum probable earthquake mmax are made for each zone the return periods and the probabilities of occurrence of various magnitudes for return periods of 50 100 and 1000 years are also computed for each zone the peak ground acceleration pga values for 20 exceedance in 50 years are then computed for the delhi region from each zone the maximum pga value considering all the zones is 0 34 g which is due to the mathura fault zone the seismogenic zones v and vi i e mathura fault zone and the sohna fault zone are observed to be contributing maximum pga values in the delhi region governing the isoacceleration contours computed for the region the seismic zonation map for the pga values at the bedrock level is obtained for the delhi region this can be used directly as input for the microzonation of ground motion at the surface by incorporating the local site conditions

sheet fractures other stress forms and some engineering implications field evidence shows that contrary to common belief sheet fractures and structures are due to compressive stress a suite of minor forms including a tents or pop ups are of similar origin this interpretation carries a range of implications for civil engineering and quarrying projects the minor forms are also indicators of seismicity

repeated intermittent earthquake cycles in the san francisco bay region forecasts of future earthquake hazard in the san francisco bay region sfbr are dependent on the distribution used for the possible magnitude of future events based on the limited observed data it is not possible to statistically distinguish between many distributions with very different tail behavior these include the modified and truncated gutenberg richter distributions and a composite distribution assembled by the working group on california earthquake probabilities there is consequent ambiguity in the estimated probability of very large and hence damaging events a related question is whether the energy released in earthquakes is a small or large proportion of the stored energy in the crust corresponding loosely to the ideas of self organized criticality and intermittent criticality respectively however the sfbr has experienced three observed accelerating moment release amr cycles terminating in the 1868 hayward 1906 san andreas and 1989 loma prieta events a simple stochastic model based on elastic rebound has been shown to be capable of producing repeated amr cycles in large synthetic catalogs we propose that such catalogs can provide the basis of a test of a given magnitude distribution via comparisons between the amr properties of the real and synthetic data our results show that the truncated gutenberg richter distribution produces amr behavior closest to the observed amr behavior the proviso is that the magnitude parameters b and m max are such that a sequence of large events that suppresses activity for several centuries is unlikely to occur repeated simulation from the stochastic model using such distributions produces 30 year hazard estimates at various magnitudes which are compared with the estimates from the 2003 working group on california earthquake probabilities

what controls an earthquake s size results from a heterogeneous cellular automaton the controls on an earthquake s size are examined in a heterogeneous cellular automaton that includes stress concentrations which scale with rupture size large events only occur when stress is highly correlated with strength over the entire fault although the largest events occur when this correlation is the highest the magnitude of the correlation has no predictive value as events of all magnitudes occur during times of high stress strength correlation rather the size of any particular event depends on the local stress heterogeneity encountered by the growing rupture patterns of energy release with time for individual ruptures reflect this heterogeneity and many show nucleation type behaviour although there is no relation between the duration of nucleation phase and the size of the event these results support the view that earthquake size is determined by complex interactions between previous event history and dynamic stress concentrations and suggest that deterministic earthquake prediction based on monitoring nucleation zones will not be possible

seismicity parameters and spatially smoothed seismicity model for iran abstract in the present study seismicity parameters seismic activity value and maximum regional magnitude of the iranian plateau are computed for sites equally distributed all over the country on a grid of 1 1 decimal degree the most complete available catalog including historical and instrumental earthquakes of the plateau from 734 b c to a d 2011 is first prepared from numerous resources earthquakes within a 200 km buffer surrounding each grid point are selected and historical and instrumental parts are more accurately specified based on the completeness test of stepp 1972 the instrumental part is also analyzed to identify the various completeness intervals and the minimum completeness magnitude for each interval is determined by the maximum curvature method next the seismicity parameters are calculated from uncertain and incomplete data by the maximum likelihood procedure of kijko and sellevoll 1989 1992 and kijko 2004 after removing aftershocks and foreshocks the spatial variation of seismicity parameters is illustrated in the form of contour maps over the whole iranian plateau for the first time the value corresponding to the magnitudes m w 4 varies over the plateau from 0 7 to 23 4 and the highest values are located in the zagros and alborz mountains confirming that a large portion of the seismic deformation in the plateau is accommodated in these regions the estimated values for all points lie between 1 3 and 2 9 this spatial distribution of values demonstrates the crustal heterogeneity over the plateau low values in northeast and east iran also indicate high probability of large earthquake occurrence it is observed that the estimated m max is between m w 6 5 and 8 and hence most of that part of the country may experience large earthquakes the obtained results are important for two aspects 1 new seismotectonic models could be proposed by combining the presented maps with geological geodetic and tectonic data and 2 these results together with a detailed geological data describing potential seismogenic sources can be used directly to evaluate ground motion hazard for engineering design and generate seismic hazard maps an approximate and gross estimate of peak ground acceleration pga level at bedrock for 2 and 10 probabilities of exceedance in a 50 year period is also computed using an area source model characterized by the presented seismicity parameters the regional distribution of the estimated pga sheds a new light on facilitating risk management and allocating national resources for mitigating potential losses at a country based level online material table of completeness magnitude and seismicity parameters

non poissonian earthquake occurrence in coupled stress release models and its effect on seismic hazard summary most seismic hazard estimations are based on the assumption of a poisson process for earthquake occurrence even though both observations and models indicate a departure of real seismic sequences from this simplistic assumption instrumental earthquake catalogues show earthquake clustering on regional scales while the elastic rebound theory predicts a periodic recurrence of characteristic earthquakes on longer timescales for individual events recent implementations of time dependent hazard calculations in california and japan are based on quasi periodic recurrences of fault ruptures according to renewal models such as the brownian passage time model however these renewal models neglect earthquake interactions and the dependence on the stressing history which might destroy any regularity of earthquake recurrences in reality to explore this we investigate the coupled stress release model a stochastic version of the elastic rebound hypothesis in particular we are interested in the time variability of the occurrence of large earthquakes and its sensitivity to the occurrence of gutenberg richter type earthquake activity and fault interactions our results show that in general large earthquakes occur quasi periodically in the model the occurrence probability of large earthquakes is strongly decreased shortly after a strong event and becomes constant on longer timescales although possible stress interaction between adjacent fault zones does not affect the recurrence time distributions in each zone significantly it leads to a temporal clustering of events on larger regional scales the non random characteristics especially the quasi periodic behaviour of large earthquakes are even more pronounced if stress changes due to small earthquakes are less important the recurrence time distribution for the largest events is characterized by a coefficient of variation from 0 6 to 0 84 depending on the relative importance of small earthquakes

a quantitative appraisal of earthquake hazard parameters evaluated from bayesian approach for different regions in iranian plateau in this study we used the program for seismic hazard bayesian estimate which was elaborated by alexey lyubushin our study is the next in the sequence of applications of this software to seismic hazard assessment in different regions of the world however earthquake hazard parameters of maximum regional magnitude m hbox max value and seismic activity rate or intensity and their uncertainties for the 15 different source regions in iranian plateau have been evaluated with the help of a complete and homogeneous earthquake catalogue during the period 1900 2014 with m text w 4 0 the estimated m hbox max values varies between 6 25 and 8 37 lowest value is observed in the zagros foredeep whereas highest value is observed in the makran also it is observed that there is a strong relationship between the estimated maximum earthquake magnitudes estimated by bayesian approach and maximum observed magnitudes moreover in this study quantiles of functions of distributions of true and apparent magnitudes for future time intervals of 5 10 20 50 and 100 years are calculated with confidence limits for probability levels of 50 70 and 90 in 15 different source regions based on computed earthquake hazard parameters the prerequisite guides to the earthquake estimation of the parameters referred to as the most seismically active regions of iranian plateau the makran and east iran show earthquake magnitude greater than 8 0 in next 100 years with 90 probability level as compared to other regions which declares that these regions are more susceptible to occurrence of large earthquakes the outcomes which obtained in the study may have useful implications in the probabilistic seismic hazard studies of iranian plateau

the upper truncated power law applied to earthquake cumulative frequency magnitude distributions evidence for a time independent scaling parameter earthquake cumulative frequency magnitude cfm distributions are described by the gutenberg richter power law where the exponent is the b value although it has been reported that the b value changes before large earthquakes we find that an upper truncated power law applied to earthquake cfm distributions yields a time independent scaling parameter herein called the value we analyze earthquakes associated with subduction of the nazca plate beneath south america and find a region of isolated seismic activity at depths greater than 500 km between 20 s and 30 s for the entire record 1973 2000 the earthquake cfm distribution in this isolated region is well described by a gutenberg richter power law with b 0 58 the data set includes several large seismic events with m b 6 8 a power law applied to the cfm distributions for short time intervals between the large events yields b values greater than the b value for the entire record cfm distributions for the short time intervals are better described by an upper truncated power law than by a power law the value determined by applying an upper truncated power law to the short time intervals is equal to the b value obtained by applying the gutenberg richter power law to the entire record temporal changes in b value are due to temporal fluctuations in maximum magnitude analysis of four flinn engdahl regions two in subduction zones and two along spreading ridges demonstrates wider applicability of the results the value is an unchanging characteristic of the system that may be determined from a short term record manuscript received 2 july 2001

groundwater flows in weathered crystalline rocks impact of piezometric variations and depth dependent fracture connectivity summary groundwater in shallow weathered and fractured crystalline rock aquifers is often the only perennial water resource especially in semi arid region such as southern india understanding groundwater flows in such a context is of prime importance for sustainable aquifer management here we describe a detailed study of fracture properties and relate the hydraulic connectivity of fractures to groundwater flows at local and watershed scales investigations were carried out at a dedicated experimental hydrogeological park in andhra pradesh southern india where a large network of observation boreholes has been set up twenty height boreholes have been drilled in a small area of about 18 000 m 2 in which borehole loggings and hydraulic tests were carried out to locate the main flowing fractured zones and investigate fractures connectivity several hydraulic tests nineteen slug tests and three pumping tests performed under two water level conditions revealed contrasting behavior under high water level conditions the interface including the bottom of the saprolite and the first flowing fractured zone in the upper part of the granite controls groundwater flows at the watershed scale under low water level conditions the aquifer is characterized by lateral compartmentalization due to a decrease in the number of flowing fractures with depth depending on the water level conditions the aquifer shifts from a watershed flow system to independent local flow systems a conceptual groundwater flow model which includes depth dependent fracture connectivity is proposed to illustrate this contrasting hydrological behavior implications for watershed hydrology groundwater chemistry and aquifer vulnerability are also discussed

a mutually consistent seismic hazard source model for southern california abstract a previous attempt to integrate geological geodetic and observed seismicity data into a probabilistic hazard source model predicted a rate of magnitude 6 to 7 earthquakes significantly greater than that observed historically one explanation was that the discrepancy or apparent earthquake deficit is an artifact of the upper magnitude limit built into the model this was controversial however because removing the discrepancy required earthquakes larger than are seen in the geological record and larger than implied from empirical relationships between fault dimension and magnitude although several articles have addressed this issue an alternative integrated source model without an apparent deficit has not yet appeared we present a simple geologically based approach for constructing such a model that agrees well with the historical record and does not invoke any unsubstantiated phenomena the following factors are found to be influential the b value and minimum magnitude applied to gutenberg richter seismicity the percentage of moment released in characteristic earthquakes a round off error in the moment magnitude definition bias due to historical catalog incompleteness careful adherence to the conservation of seismic moment rate uncertainty in magnitude estimates obtained from empirical regressions allowing multi segment ruptures cascades and the time dependence of recurrence rates the previous apparent deficit is shown to have resulted from a combination of these factors none alone caused the problem nor solves it the model presented here is relatively robust with respect to these factors

second order moment of central california seismicity 1969 1982 the second order moment cross correlation function of earthquakes in the u s geological survey central california catalog between 1969 and 1982 was calculated with respect to a magnitude threshold m 4 0 over interevent distances up to 80 km and interevent times up to 320 days the statistical procedure results in a representation of the spatial temporal structure of the catalog associated with m 4 0 earthquakes and is capable of revealing patterns too weak to be detected in the space time distribution of seismicity for individual earthquake sequences a method is introduced for identifying aftershocks based on a physical two parameter model of the earthquake interaction process the results show that the aftershock process dominates the second order moment and may even obscure the statistical expression of a precursory process a concentration of foreshocks within 15 km and 3 days of m 4 0 main shocks exhibits an apparent migration toward the main shock loci with velocity 2 6 5 3 km d this concentration may be related to an observed tendency for m 4 0 events to cluster auto correlate over this interevent range with the identified aftershocks removed the residual catalog is poissonion in space and time when two m 4 0 earthquakes occur within 80 km and 40 days of each other aftershock productivity appears to be relatively enhanced in the earlier sequence this suggests that aftershock populations are not solely dependent on their main shocks and that unusually productive aftershock sequences may be predictors of future moderate earthquakes

a review of source models of the 2015 illapel chile earthquake and insights from tsunami data the 16 september 2015 illapel chile earthquake and associated tsunami have been studied by many researchers from various aspects this paper reviews studies on the source model of the earthquake and examines tsunami data the illapel earthquake occurred in the source region of previous earthquakes in 1943 and 1880 the earthquake source was studied using various geophysical data such as near field seismograms teleseismic waveform and backprojection gps and insar data and tsunami waveforms most seismological analyses show a duration of 100 s with a peak at 50 s the spatial distribution has some variety but they all have the largest slip varying from 5 to 16 m located at 31 s 72 w which is 70 km nw of the epicenter the shallow slip seems to be extended to the trench axis a deeper slip patch was proposed from high frequency seismic data a tsunami earthquake model with a total duration of 250 s and a third asperity south of the epicenter is also proposed but we show that the tsunami data do not support this model

earthquake hazard parameters in crete island and its surrounding area inferred from bayes statistics an integration of morphology of the seismically active structures and seismological data the study addresses the evaluation of earthquake hazard parameters such as maximum regional magnitude mmax and the slope of gutenberg richter law where b log e for the hellenic wadati benioff zone and the overriding lithospheric plate in the area of crete and its surroundings the seismicity of the area is divided in a cellular 1 0 1 0 manner allowing analysis of the localized earthquake hazard parameters and graphical representation of their spatial variation our approach incorporates the recently updated earthquake catalogue for greece and the adjacent areas the consideration of the morphology of the deep seismically active structures in the studied area and use of a probabilistic procedure for estimating the earthquake hazard parameters one of the main inconsistencies in the earthquake hazard assessment is the estimation of the maximum magnitude and the related uncertaint y the bayesian approach applied in the present is a straightforward technique for evaluating the earthquake hazard parameters and is based on the following assumptions poissonian character of seismic events flow a frequency magnitude law of gutenberg richter s type with cutoff maximal value for estimated parameter and a seismic catalogue having a rather sizeable number of events i e 50 events at least per cell for five cells in which the number of events is less than 50 an effort is made to produce synthetic data the re assessed parameters obtained from the synthetic data show no significant difference and the real data of the five cells are finally taken into account although the estimated uncertainty is high for four random cells we constructed hazard curves showing the probabilities that a certain magnitude m will be exceeded in one year and the return periods in years that are expected for a given magnitude these are particularly useful for the mapping of earthquake hazard in regions of either low or high seismic activity as is crete and the adjacent area the obtained results show that the w and e parts of both subducting and overriding plates differ in the spatial distribution of all the estimated earthquake hazard parameters the mmax distribution indicates strong coupling between the western portions of the interacting plates mmax 6 3 to the south of 36 n the smaller values of mmax mmax 1 0 are found to the south and east of crete for the wadati benioff zone and over the central part of the island and the area to the northeast of it cell 11 for the continental wedge which suggests nonuniform stress field and or heterogeneous material

hydraulic conductivity of compacted bentonite sand mixtures in the absence of impervious natural soils compacted mixtures of bentonite and sand have been used to form barriers to fluids and the focus of this paper is on the hydraulic conductivity behaviou

generalised seismic hazard maps for the pannonian basin using probabilistic methods a set of seismic hazard maps expressed as horizontal peak ground acceleration is presented for a large area of central eastern europe covering the pannonian basin and surrounding area these maps are based on a a compound earthquake catalogue for the region b a seismic source model of 50 zones compiled on the basis of tectonic divisions and seismicity and c a probabilistic methodology using stochastic monte carlo modelling it is found that the highest hazard in the region derives from intermediate focus earthquakes occurring in the vrancea seismic zone here the hazard exceeds 0 4 g at return periods of 475 years special account has been taken of the directional nature of attenuation from this source the maps are intended for use in studies of comparative methodologies for seismic hazard assessment

sediment thicknesses of the western anatolia graben structures determined by 2d and 3d analysis using gravity data abstract western turkey is tectonically one of the most active and rapidly deforming regions of continental crust in the world the most pronounced structural and morphological features of this region are defined by normal faulting in an e w direction which creates the boundaries of the buyuk menderes kucuk menderes and gediz grabens the graben systems may have become active between 11 7 ma and are now deeper than the surrounding topography the gediz and buyuk menderes grabens exhibit negative bouguer gravity anomalies the bouguer gravity anomalies increase towards the center of the aegean sea in a regional sense the grabens are filled with recent sediments giving rise to relative negative gravity anomalies these anomalies were interpreted using 2d and 3d gravity inversion techniques in order to determine the depth to the metamorphic basement inversion of geophysical anomalies implies fitting the observed data to theoretical anomalies possibly produced by subsurface bodies inversion of gravity anomalies is a non linear problem in the sense that body parameters are not linearly related to the anomalies gravity anomalies caused by structures are mostly determined by a 2d model which has an n sided polygonal cross section for non linear problems theoretically it is more suitable to determine the parameters of the structure by a series of juxtaposing prisms or vertical dykes extending to infinity rather than using a single n side polygonal model the depths to the top surfaces of a rectangular prisms with infinite depth represent the relief of the basement the basement relief can be computed on the basis of density contrast if the reference depth is assessed as a result of 3d analysis of the bouguer gravity map the maximum thickness of sedimentary cover appears to be more than 2 0 and 1 5 km for the gediz and buyuk menderes grabens respectively towards the saraykoy kizildere area the sedimentary thickness cover thickens to more than 2 0 km 2d analysis of the bouguer gravity profiles indicate that the maximum thickness of the sedimentary cover is between 2 5 and 3 5 km in the buyuk menderes graben and between 0 5 and 2 0 km in the gediz graben

application of a bayesian approach for estimation of seismic hazard parameters in some regions of the circum pacific belt the maximum possible regional magnitude mmax and other seismic hazard parameters like which is the slope of gutenberg richter law and which is the intensity rate of seismic activity are estimated in eight seismic regions of the west side of the circum pacific belt the bayesian approach as described by pisarenko et al 1996 pisarenko and lyubushin 1997 1999 is a straightforward technique of estimating the seismic hazard the main assumptions for the method applied are a poissonian character of seismic events flow a frequency magnitude law of gutenberg richter s type with cutoff maximum value for the estimated parameter and a seismic catalog which have a rather sizeable number of events we also estimated the quantiles of the probabilistic distribution of the apparent mmax for future given time length intervals

general theory of the modified gutenberg richter law for large seismic moments abstract it is well known that the gutenberg richter power law distribution has to be modified for large seismic moments because of energy conservation and geometrical reasons several models have been proposed either in terms of a second power law with a larger b value beyond a crossover magnitude or based on a hard magnitude cut off or a soft magnitude cut off using an exponential taper since large scale tectonic deformation is dominated by the very largest earthquakes and since their impact on loss of life and properties is huge it is of great importance to constrain as much as possible the shape of their distribution we present a simple and powerful probabilistic theoretical approach that shows that the gamma distribution is the best model given the two hypotheses that the gutenberg richter power law distribution holds in absence of any condition and that one or several constraints are imposed either based on conservation laws or on the nature of the observations themselves the selection of the gamma distribution does not depend on the specific nature of the constraint we illustrate the approach with two constraints the existence of a finite moment release rate and the observation of the size of a maximum earthquake in a finite catalog our predicted soft maximum magnitudes compare favorably with those obtained by kagan for the flinn engdahl regionalization of subduction zones collision zones and midocean ridges

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

australia s large earthquakes and recent fault scarps abstract nineteen large earthquakes up to magnitude ms 6 8 have occurred within continental australia this century and at least seven recent prehistoric fault scarps have been discovered the magnitude of the earthquake causing each of these prehistoric fault scarps has been estimated from the observed fault length and maximum scarp height and none exeeds magnitude 7 0 their occurrence demonstrates that the australian plate is undergoing significant internal deformation but as yet there is no model to explain their cause nor the likely site of the next large earthquake the absence of earthquake epicentres on the current tectonic map of australia is a regrettable omission

estimating rate and state friction parameters using a two node stochastic model for aftershocks abstract the well known omori and modified omori omori utsu empirical formulae describe the decay in the rate of occurrence of aftershocks dieterich s rate and state dependent constitutive law for aftershock production produces a similar temporal formula with physically interpretable parameters such as the shear stressing rates the normal stress and a fault constitutive parameter this naturally leads to an interest in estimating these parameters from earthquake catalogs which requires a simpler stochastic model an alternative to the epidemic type aftershock sequence etas model is the two node seismic transfer and release model where one node represents the mainshock process and a secondary node represents the aftershock zone the aftershock decay rate in the two node model equals that derived from dieterich s rate and state dependent constitutive law and the inclusion of aseismic slip in the aftershock zone allows for values of p 1 in the best matching modified omori law the two node model can be easily fitted to aftershock data and has an application to aftershock stacking for estimating p values the equivalence between the rate and state and two node aftershock rates forms a bridge between a formula derived from physical considerations and a phenomenological stochastic model we show how this can be exploited by identifying physical units for the parameters in the latter to estimate the fault constitutive parameters and the stressing rates in dieterich s formula through a best fit inversion on real aftershock sequences the procedure is illustrated using data from four japanese earthquakes

seismic moment frequency relation for shallow earthquakes regional comparison we determine the parameter values for the seismic moment frequency relation using flinn engdahl s regionalization of global seismicity and the harvard centroid moment tensor data the earthquake size distribution is approximated by the gamma law a version of the gutenberg richter distribution with an exponential taper at the maximum moment there is no statistically significant variation of the fj value the analog of the b value for all seismic regions except for the midocean ridge systems for the latter regions fj 0 93 whereas for all other zones fj 0 63 the maximum moment mxg can be statistically evaluated only for subduction zones treated as a whole mxg 10 21 2 x 10 22 newton m which corresponds to the worldwide mxg value for other regions as well as for single subduction zones mxg is determined by comparing the number of events in each zone with the seismic moment rate calculated on the basis of the nuvel 1 model of plate motion for subduction zones we obtain the estimate of mxg which agrees with the statistical value giving evidence that most tectonic deformation is released by earthquakes we test the hypothesis that no statistically significant variation in mxg occurs in subduction and continent collision zones the hypothesis cannot be rejected with available data for the midocean ridges the mxg estimate cannot be unambiguously determined it is quite possible that the estimate is significantly biased because only a small part of tectonic deformation at the ridges is released by earthquakes these results have importance in evaluating seismic risk and may also lead to developing a physical theory for earthquake generation

stress relief buckles in the mcfarland quarry ottawa six quarry floor buckles in a west end ottawa bedrock quarry are described and a semi quantitative estimate of the stress field is inferred from them the maximum principal stress component is hori

m 6 earthquakes in southern california during the twentieth century no evidence for a seismicity or moment deficit abstract a broadly based report on seismic hazards in southern california wgcep 1995 concluded that the predicted seismicity exceeds that observed since 1850 a subsequent independent analysis argued that infrequent huge m 8 earthquakes are needed to explain the low rate of large earthquakes jackson 1996 frequency magnitude relationships and earthquake reporting suggest that the 1903 to 1997 catalog we present here with a b value of 1 0 and a rate of m 6 shocks of 0 42 to 0 49 yr 1 is nearly complete in contrast the 1850 to 1994 catalog used by wgcep is incomplete before the turn of the century and thus its reported seismicity rate of 0 32 m 6 shocks yr 1 is too low principally because the wgcep 1995 model results in b values of up to 4 0 for regions of lesser and blind faults the rate of m 6 shocks off the san andreas system predicted by the wgcep 1995 model is three times greater than that observed in this century because they obtained b 0 4 for m b 2 2 for m 7 3 on major faults their expected rate of m 7 san andreas shocks is twice as high as observed thus part of the seismicity and moment discrepancy identified by wgcep was caused by use of an incomplete catalog and part was caused by inappropriate b values we obtain a southern california moment release rate of 8 to 12 10 18 n m yr 1 which cannot be distinguished from the moment release estimated by fault slip or the moment accumulation inferred from plate motions or geodetically measured shear strain we thus find no evidence for a moment deficit significant aseismic moment release or for rare m 8 earthquakes off the san andreas fault system finally the number of m 6 earthquakes per decade does not depart significantly from a poisson process during this century and thus we find no evidence that the rate of seismicity is increasing now or at any other time since 1900

large earthquake cycles and intermittent criticality on heterogeneous faults due to evolving stress and seismicity 1 we analyze evolving stress and seismicity generated by three realizations of a discrete model of a strike slip fault in a three dimensional 3 d elastic half space using five functions of stress and five functions of seismicity the first model f has realistic dynamic weakening static minus dynamic frictions the second fc has zero critical dynamic weakening and the third sys is constrained to produce only system size events the results for model f show cyclical development saturation and destruction of fluctuations and long range correlations on the fault punctuated by the system size events the development stage involves evolution of stress and seismicity to distributions having broad ranges of scales evolution of response functions toward scale invariant behavior increasing seismicity rate and event sizes and increasing hypocenter diffusion most functions reach asymptotically stable values around 2 3 of the cycle and then fluctuate until one event cascades to become the next large earthquake in model fc the above evolution is replaced by scale invariant statistical fluctuations while in model sys the signals show simple cyclic behavior the results suggest that large earthquake cycles on heterogeneous faults with realistic positive dynamic weakening are associated with intermittent criticality produced by spontaneous evolution of stress heterogeneities toward a critical level of disorder having a broad range of scales the stress evolution and development of large earthquake cycles may be tracked with seismicity functions

an evaluation of tsunami hazard using bayesian approach in the indian ocean abstract the present study deals with the estimation of tsunami hazard parameters maximum regional tsunami intensity imax slope value where b log10 e of tsunami intensity frequency relationship and tsunami activity rate in the whole indian ocean as well as andaman sumatra java asj region using bayesian statistics technique for this purpose a reliable homogeneous and complete tsunami catalog during the period 1797 to 2006 with tsunami intensities soloviev imamura intensity scale i 2 0 having average wave heights h 2 83 m is utilized the slope b value of linear tsunami intensity frequency relationship log10 n a b i of g r type for observed tsunami data with intensities i 2 0 is calculated as 0 41 the applied method of bayesian statistics follow three assumptions viz poissonian character of tsunami events existence of the frequency intensity relation of g r type with a cut off maximum value of tsunami intensities and catalog contains rather sizable events in this study the maximum regional tsunami intensity imax has been estimated as 5 39 0 30 and 5 41 0 31 for the whole indian ocean and asj regions respectively which is reasonably comparable to the maximum observed tsunami intensity of 5 0 for august 27 1883 indonesia tsunami the slope value of tsunami intensity frequency relationship is calculated as 0 81 for both the indian ocean and asj regions by bayesian statistics theory we have also estimated quantiles of true and apparent tsunami intensities for future time intervals of 20 30 40 and 50 years with confidence limits for probability levels of 50 60 70 80 90 and 95 in the indian ocean along with asj region it is observed that the differences between true and apparent quantiles of tsunami intensities are negligible revealing that a good quality of tsunami data is used in the study the results estimated in the present study have potential useful implications in the probabilistic tsunami hazard assessment in the indian ocean region

an overview on the seismic zonation and microzonation studies in india abstract the present study presents a review on the progressive development of the seismic zonation map of india both from official agencies and also from independent individual studies the zonation map have been modified and updated regularly with the occurrence of major destructive earthquakes over the years in the indian subcontinent with the addition of new data this study discusses the criteria chosen for the progressive zonation and the major earthquakes that were responsible for retrospection of the earlier published maps the seismic zonation maps of india have also been prepared by various independent workers by adopting different approaches to achieve the purpose of the zonation despite the endeavors from various sources to provide a solution for the problem of earthquake hazards in india there were many limitations on the zonation map as it gives the picture at a regional scale mostly on the bedrock level without addressing the local site conditions but nevertheless the seismic zonation map gives basic guidelines for any region to know the hazard scenario and if any city or urban population is under threat from seismic point of view further site specific seismic microzonation may be carried out in the international scenario the global seismic hazard assessment program gshap in 1999 prepared a hazard map for world in terms of peak ground acceleration pga with a 10 probability of exceedance in 50 years but it turned out to be an underestimation of the hazard parameter when compared with the observed pga to tackle the problem of seismic hazards there was a need to have a detail study on the local site conditions in terms of its geological geophysical and geotechnical properties with the advent of better instrumentation and knowledge on the mechanics of earthquakes it was possible to identify zones of hazards at a local level and this gives rise to the study of seismic microzonation seismic microzonation work has been carried out in india in some of the strategic important mega cities and industrial build up that has the potential of being damaged from future earthquakes as has been shown in the past though the microzonation map is not the final output map as it can still be updated at later stage with more input data it does provide a more realistic picture on the site specific seismic hazard