physical links between crustal deformation seismic moment and seismic hazard for regions of varying seismicity summary seismic moment release rates m0 inferred from a weibull frequency magnitude distribution and its extreme value equivalent are compared with observation the seismotectonically diverse regions studied all exhibit the curvature of a log linear frequency magnitude plot associated with applying a maximum magnitude to earthquake recurrence statistics the inferred seismic moment release rates are consistent with available crustal deformation data within uncertainties resulting from the line fit and in magnitude determination the uncertainties for the regions studied southern california the new madrid seismic zone the central and eastern mediterranean and mainland uk vary from at worst an order of magnitude down to a factor of 2 or 3 this agreement can be used to justify the extrapolation of frequency magnitude statistics beyond the historical and instrumental era in seismic hazard studies as a test of the stationarity of short term statistics against long term effects a striking example of a bimodal seismicity distribution is observed in the new madrid zone this can be interpreted as being due to the superposition of two distinct seismogenic source types observed in the area a quantitative analysis of the separate orders of seismicity observed in the frequency magnitude statistics comparing the different maximum magnitudes and inferred seismic moment release rates with those observed supports this hypothesis superposition of many such seismogenic sources can explain the linearity observed in global frequency versus seismic moment magnitude statistics

integrated seismic hazard analysis of the wasatch front utah we examined the combined effects of different sources that influence earthquake hazard of the populated wasatch front utah we first evaluated the fault stress interaction of the two largest historic earthquakes of the intermountain seismic belt isb the 1959 hebgen lake montana m s 7 5 and the 1983 borah peak idaho m s 7 3 earthquakes which experienced multisegment normal faulting ruptures estimates of the static stress change for these events revealed an increase in coulomb failure stress in areas of extended aftershocks these observations suggested that fault stress analysis is applicable in evaluating the spatial distribution of aftershocks after large normal faulting earthquakes in the same extensional stress regime of the eastern basin range including the wasatch front utah which encompasses the 370 km long wasatch fault and surrounding faults on the basis of this result we applied the modeling technique to the historically seismically quiescent wasatch fault and examined the relation between the pattern of stress change and the space time distribution of paleoearthquakes ages and locations of the wasatch fault paleoseismic data imply 17 single segment or 11 multisegment ruptures in the past 5 6 kyr we prefer the multisegment model because almost all of the large historical normal faulting earthquakes in the isb were multisegment fitting the along fault displacements by an analytic half ellipse function provides a first order distribution of the displacement over an entire rupture length and allows new estimates of fault slip rates and seismic moment with these data we also estimated the occurrence rate of m w 6 6 wasatch paleoearthquakes and showed that the rate was about three times higher than that inferred by the historical seismicity this result along with new information from a megatrench on the wasatch fault near salt lake city that revealed no scarp forming earthquakes between ca 9 0 and 15 5 ka suggests that large wasatch fault events in the past 5 6 kyr may be clustered the recurrence rate of large earthquakes estimated by the geodetic measured strain on the other hand is three to four times higher than that estimated by the long term fault slip rate this difference together with the observation of a low regional strain rate from historical seismicity suggests that cumulative aseismic deformation may be significant on the wasatch fault we also examined a major consideration for along strike segmentation namely how stress contagion could affect the probability of failure of adjacent faults including paleoearthquake derived fault slip rates global positioning system derived geodetic moment rates and the effect of stress contagion in the earthquake hazard estimation for a specific location in the salt lake valley revealed an increase in the annual frequency of peak ground acceleration 0 25 g by a factor of 1 4 4 0 and 5 4 respectively compared with that derived from historical seismicity only manuscript received 31 may 2001

the gutenberg richter or characteristic earthquake distribution which is it abstract paleoearthquake and fault slip rate data are combined with the cit usgs catalog for the period 1944 to 1992 to examine the shape of the magnitude frequency distribution along the major strike slip faults of southern california the resulting distributions for the newport inglewood elsinore garlock and san andreas faults are in accord with the characteristic earthquake model of fault behavior the distribution observed along the san jacinto fault satisfies the gutenberg richter relationship if attention is limited to segments of the san jacinto that are marked by the rupture zones of large historical earthquakes or distinct steps in fault trace the observed distribution along each segment is consistent with the characteristic earthquake model the gutenberg richter distribution observed for the entirety of the san jacinto may reflect the sum of seismicity along a number of distinct fault segments each of which displays a characteristic earthquake distribution the limited period of instrumental recording is insufficient to disprove the hypothesis that all faults will display a gutenberg richter distribution when averaged over the course of a complete earthquake cycle but given that 1 the last 5 decades of seismicity are the best indicators of the expected level of small to moderate size earthquakes in the next 50 years and 2 it is generally about this period of time that is of interest in seismic hazard and engineering analysis the answer to the question posed in the title of the article at least when concerned with practical implementation of seismic hazard analysis at sites along these major faults appears to be the characteristic earthquake distribution

reassessment of probabilistic seismic hazard in the marmara region abstract in 1999 the eastern coastline of the marmara region turkey witnessed increased seismic activity on the north anatolian fault naf system with two damaging earthquakes m 7 4 kocaeli and m 7 2 duzce that occurred almost three months apart these events have reduced stress on the western segment of the naf where it continues under the marmara sea the undersea fault segments have been recently explored using bathymetric and reflection surveys these recent findings helped scientists to understand the seismotectonic environment of the marmara basin which has remained a perplexing tectonic domain on the basis of collected new data seismic hazard of the marmara region is reassessed using a probabilistic approach two different earthquake source models 1 the smoothed gridded seismicity model and 2 fault model and alternate magnitude frequency relations gutenberg richter and characteristic were used with local and imported ground motion prediction equations regional exposure is computed and quantified on a set of hazard maps that provide peak horizontal ground acceleration pga and spectral acceleration at 0 2 and 1 0 sec on uniform firm rock site condition 760 m sec average shear wave velocity in the upper 30 m these acceleration levels were computed for ground motions having 2 and 10 probabilities of exceedance in 50 yr corresponding to return periods of about 2475 and 475 yr respectively the maximum pga computed at rock site is 1 5 g along the fault segments of the naf zone extending into the marmara sea the new maps generally show 10 to 15 increase for pga 0 2 and 1 0 sec spectral acceleration values across much of marmara compared to previous regional hazard maps hazard curves and smooth design spectra for three site conditions rock soil and soft soil are provided for the istanbul metropolitan area as possible tools in future risk estimates

a note on adding viscoelasticity to earthquake simulators abstract here i describe how time dependent quasi static stress transfer can be implemented in an earthquake simulator code that is used to generate long synthetic seismicity catalogs most existing seismicity simulators use precomputed static stress interaction coefficients to rapidly implement static stress transfer in fault networks with typically tens of thousands of fault patches the extension to quasi static deformation which accounts for viscoelasticity of earth s ductile lower crust and mantle involves the precomputation of additional interaction coefficients that represent time dependent stress transfer among the model fault patches combined with defining and evolving additional state variables that track this stress transfer the new approach is illustrated with application to a california wide synthetic fault network

convergence improvement and noise attenuation considerations for beyond alias projection onto convex sets reconstruction a reconstruction method known as projection onto convex sets pocs is an effective uncomplicated and robust method for the recovery of irregularly missing seismic traces however slow convergence of the pocs reconstruction method could jeopardize its computational appeal for this reason we investigate the performance of the pocs reconstruction method in terms of different threshold schedules and present a new data driven threshold that leads to an efficient implementation of the pocs method in particular we show that high quality solutions can be obtained in a few iterations in addition we address an important issue with the classical implementations of pocs reconstruction in that they cannot interpolate regularly missing data to solve this problem we introduce a masking operator that is based on a dominant dip scanning method into the pocs iteration at the end we present a variant of the pocs method that permits de noising seismic volumes during the reconstruction stage this is achieved by defining a weighted trace re insertion strategy that alleviates the influence of noisy traces in the final reconstruction of the seismic volume we show the effectiveness of the proposed method using synthetic and field data

earthquake frequency distribution and the mechanics of faulting the level of intraplate seismicity in japan generally shows a positive correlation with the density of quaternary faulting in southwest japan where intraplate seismicity is concentrated on land rates of seismic moment release m 0 are similar when calculated from either the 400 year historical record of seismicity or geologically determined slip rates of quaternary faults a data set of 18 earthquakes with seismic moments m0 ranging from 0 01 to 3 1027 dyn cm shows a relationship between rupture lengthl and m0 log m0 23 5 1 94 log l when seismic moment on each quaternary fault is assumed to occur in discrete events every t m0 m 0g years where m0 is estimated for a rupture extended over the entire fault length and m 0g is proportional to the slip rate of each quaternary fault the moment frequency distribution of earthquakes log n a b log m0 predicted from the geologic record is virtually identical to that seen with the 400 year record of seismicity in contrast if it is assumed that earthquakes on each fault occur according to the gutenberg richter relation we obtain poor agreement with the observed seismicity thus while regional seismicity satisfies the relation log n a b log m0 or equivalently log n a b log m where m is magnitude it appears that seismicity on individual faults does not this further implies that the primary factor that leads to the magnitude frequency distribution in regional seismicity studies is the relative distribution of the slip rates and lengths of preexisting faults

statistics of small earthquakes and frequency of occurrence of large earthquakes along the mexican subduction zone abstract the validity of the gutenberg richter g r frequency magnitude relation over a wide range of magnitudes is usually accepted and the statistics of small earthquakes is often extrapolated to predict the frequency of occurrence of large earthquakes we take noaa and pde data from 1963 to 1981 related to the mexican subduction zone h 65 km and convert m b to m s in the range of 3 3 m b 5 7 for this conversion we use regression of m s on m b for mexican and central american events as well as an m s m b regression based on worldwide data wyss and habermann 1982 we also take into account the standard error in m s this may be important since the number of events decreases as m b increases the m s data of 18 5 yr is normalized to 75 5 yr and is compared to the statistics of observed large earthquakes m s 6 4 for the period 1906 to 1981 it is found that the g r relation in the range 4 5 m s 6 0 when extrapolated grossly underestimates the observed frequency of large earthquakes m s 6 5 for the oaxaca and jalisco regions there is strong evidence that the plate interface in the oaxaca region consists of a few 3 or 4 large fault zones each of which cyclically ruptures over its entire dimension without giving rise to smaller events in the manner implied by the g r relation the result is of profound importance in seismic risk analysis and in the understanding of fault mechanics this phenomenon has been reported for only a few regions e g turkey bath 1981 japan wesnousky et al 1983 it may have escaped detection in other regions due to a variety of causes the most important being the long recurrence periods of large earthquakes

surficial slip and rupture geometry on the beichuan fault near hongkou during the mw 7 9 wenchuan earthquake chinasurficial slip and rupture geometry on beichuan fault near hongkou during the wenchuan earthquake

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

seismic energy mapping applied to sweden abstract the release of seismic wave energy provides a dynamic seismicity parameter of general applicability the moving block method is used for the seismic energy mapping of sweden on this basis some general problems connected with such mapping are discussed maps of this type may be useful for estimating other related quantities e g the maximum magnitude to be expected at any point

detecting strain in the yucca mountain area nevada from repeated surveys of the relative motions between geodetic stations claim black mile 67tjs and wahomie fig 1 from 1991 through 1997 wernicke et al 1 deduce a n65 w strain accumulation rate of 50 9 nanostrains per year 2 across the proposed high level radioactive waste disposal repository at yucca mountain nevada that strain rate is sufficient to indicate a higher than expected earthquake hazard at the repository an earlier 1983 1993 u s geological survey usgs measurement table 1 of the strain accumulation in the network black triangles in fig 1 found a n65 w strain rate of 8 20 nanostrains per year a rate not significantly different from zero 3 although the two measurements are marginally consistent at the 95 confidence level that is the difference 42 22 nanostrains per year is less than 2 standard deviations sd the earthquake hazard implications are somewhat different the usgs strain determination is the better of the two measurements wernicke et al did not include the effects of monument instability in their error budget and as a consequence have significantly underestimated the uncertainties in their measurements moreover in their interpretation of the data they did not give proper weight to the coseismic and postseismic effects of the little skull mountain earthquake june 29 1992 m 5 4

earthquake recurrence of a particular type the recurrence relation for turkish earthquakes expressed as the single frequency versus magnitude dependence exhibits significant maxima and minima reflecting true physical conditions various mathematical formulations are developed to fit the observed data for the single or the cumulative frequency and are compared with each other as regards their accuracy and simplicity the results may be applicable to regions with high seismicity

earthquake frequency and energy in greece abstract on the basis of a newly published revised earthquake catalogue for the greek area a study is made of its seismicity in terms of earthquake frequency and energy as functions of space time and magnitude in addition attempts are made to estimate the maximum possible magnitudes as functions of space the study is essentially a methodological experiment with tectonophysical and engineering results

recurrence models and parkfield california earthquakes main shocks of the earthquake sequences that occurred on the parkfield section of the san andreas fault in central california in 1922 1934 and 1966 are characterized by southeast rupture expansion over the same 20 to 30 km long section of the fault whereas the seismic moments for the 1922 and 1934 events are identical to within a precision of 10 the seismic moment for 1966 is 20 greater than for the earlier events to within a precision of 20 the parkfield area seismicity in general seems well described by a recurring moderate size characteristic earthquake repeating the same epicenter magnitude seismic moment rupture area and southeast direction of rupture expansion an unexplained 10 year advance of the 1934 event is the only discrepancy in the hypothesis that the parkfield earthquakes in 1857 1881 1901 1922 1934 and 1966 represent a strictly periodic process assuming the strictly periodic model and the absence since 1966 of the perturbations hypothesized for the 1922 to 1934 period the next characteristic parkfield earthquake should occur between 1983 and 1993

incorporating and reporting uncertainties in fault slip rates 1 quantitative slip rate estimates are essential to understanding crustal deformation processes and assessing seismic hazard computing slip rates requires two fundamental ingredients estimates of the age of an offset landforrn or deposit and displacement along the fault of interest because both of these measures contain uncertainty slip rates are inherently uncertain methods to compute and report slip rates have not been standardized and therefore slip rate data are presented inconsistently and are frequently ambiguous in particular slip rate uncertainty is often insufficiently characterized we present a rigorous probabilistic approach to computing and reporting intermediate to long term fault slip rates additionally we have developed freely available software that provides standard age and displacement uncertainty models we demonstrate the method using recent observations from the neodani and death valley fish lake valley fault zones and we compare slip rates determined using this approach with previously published results

attenuation of strong ground motion in canada from a random vibrations approach abstract theoretical relations are developed for the attenuation of horizontal peak ground acceleration pga and velocity pgv in canada with emphasis on eastern canada the theoretical basis is a composite of several approaches at intermediate epicentral distances results from random vibration theory hanks and mcguire 1981 boore 1983 which can be used to describe pga and pgv in terms of shear radiation implied by brune9s 1970 source model are applied to canadian earthquakes motions are extended into the near source region using arguments concerning magnitude scaling joyner and boore 1981 at distances greater than two crustal thicknesses ground motions are attributed largely to the lg phase and are attenuated accordingly nuttli 1982 the resulting attenuation relations for pga and pgv in eastern canada are in excellent agreement with strong motion data from moderate eastern canadian and central united states earthquakes compared to empirical attenuation relationships based on modified mercalli intensity the theoretical model predicts a stronger dependence of peak ground motions on magnitude in other respects amplitude levels and distance decay empirical and theoretical predictions are similar the model predicts that eastern events will have higher peak accelerations but similar peak velocities in comparison to their western counterparts of the same moment magnitude this arises from the relative enrichment of eastern earthquakes in higher frequencies

hybrid simulations of ground motions from local earthquakes affecting hong kong hong kong is located in a continental intraplate region within southeastern china historical records indicate that hong kong has been affected by both moderate local earthquakes and major distant ones but recent probabilistic seismic hazard analyses psha showed that the seismic hazard in hong kong was mainly dominated by strong and major earthquakes at distances between 90 and 400 km from the city further investigation on the result of the psha reveals that the conventional gutenberg richter seismicity model used in the psha may have underestimated the probability of occurrence of local large magnitude earthquakes the fact that the dangan island fault which has generated a moderate earthquake in 1874 lies only 30 km southeast of hong kong warrants a thorough investigation on the likely ground motion intensities that may be produced by local earthquakes in the future although the seismogenic potential of the dangan island fault has not been assessed definitely it could perhaps generate an m max 7 earthquake a series of ground motion simulations are carried out using a hybrid kinematic stochastic model to estimate the peak ground accelerations pgas peak ground velocities pgvs and response spectral accelerations rsas at eight representative locations within hong kong the capability of the simulation model and the appropriateness of the key parameters used in the simulations are confirmed by simulating the ground motions recorded in hong kong during a recent microearthquake on the dangan island fault the results of the simulations are used to derive a set of attenuation relationships for pga pgv and rsa that will be essential for future probabilistic and deterministic seismic hazard analyses using the spectral attenuation relationship derived it is revealed that strong earthquakes with m w 6 0 6 5 along the dangan island fault rather than major distant earthquakes m w 7 3 r 340 km would dominate the seismic hazard in hong kong for natural periods longer 1 sec which correspond to the natural periods of most buildings in hong kong it is therefore timely for the authority to initiate a series of geological investigations to determine the slip rate of the fault system more precisely to access the actual seismogenic potential of the dangan island fault

an alternative analysis of the probabilistic seismic hazard for las vegas valley nevada abstract probabilistic seismic hazard calculations relevant for rock site conditions in the las vegas valley lvv nevada have been computed these account for seismic sources not included in the current 2008 u s geological survey national seismic hazard model nshm due to insufficient knowledge or documentation using the commercial software package ez frisk the lvv is underlain by a system of mapped active normal faults that comprise the lvv fault system lvvfs with maximum potential earthquakes of m 6 8 the 2008 nshm explicitly includes only one fault of the lvvfs this analysis includes four more faults of the lvvfs plus four regional faults in addition to those included in the 2008 nshm and modifies parameters of two others as such this study demonstrates the effect of a significant modification to expectations for seismic sources these results can be considered as a what if scenario for seismic hazard of the lvv nominal peak ground acceleration pga and 5 damped spectral acceleration sa were calculated for 0 2 s and 1 0 s periods using five ground motion prediction equations gmpes a logic tree formulation accounted for uncertainty in the gmpes and source parameters hazard values for pga and sa computed at 2 8 km spacing are comparable with those of the 2008 nshm on the margins of the lvv but are considerably higher in the north central parts of the lvv near downtown las vegas and the city of north las vegas the study provides a rationale for the urgency to intensify investigations of faults in and around the lvv

asperities barriers characteristic earthquakes and strong motion prediction recent results from paleoseismology suggest that earthquakes recurrent on a given fault may often have the same characteristic length and amount of slip stable asperities and barriers which survive many earthquakes can explain these results the activity of volcano usu japan since 1977 which produced a dacite dome with a total upheaval of 180 m offered a great opportunity to study the recurrence behavior of a fault seismologists at hokkaido university revealed a family of repeated earthquakes with nearly the same amount of slip generated from the same fault plane on the crater wall along which the dome moved upward this family can be explained by the existence of a stable asperity on the crater wall and is called the asperity type family they found however another type of family of earthquakes which share the same fault plane but show a great range of variation in the amount of slip the behavior of the latter family can be explained by the presence of weak barriers over a fault plane defined by strong stable barriers and this family is referred to as the barrier type family this type of earthquake model has been used successfully in the interpretation of observed strong motion acceleration spectra from california and the results reveal the stability of local stress drop among different earthquakes the agreement found between local stress drops estimated from strong motion data and those inferred from geological observation supports the possibility for predicting earthquake strong motion directly from geological observation of the causative fault

geodetic control on recent tectonic movements in the central mediterranean area abstract during the neogene and quaternary the western mediterranean geodynamics was apparently dominated by the nearly eastward migration of the apenninic arc and the associated opening spreading of the back arc basin tyrrhenian sea however during the last 5 my the collision of the arc with the apulian platform led to a dramatic change in the tectonic setting of the area as geological processes require a long period of time to register the displacements of the different blocks it is indispensable to take into account the present day motion given by space geodesy data analysis in order to better constrain the geological models geodetic motions were derived from global positioning system gps satellite laser ranging slr and very long baseline interferometry vlbi observations collected from different networks all the geodetic solutions have been computed and combined at the centre of space geodesy cgs at matera italy the geodetic results show a nne motion of the adriatic plate with a small component of counter clockwise rotation in good agreement with the geological and geophysical observations in the southern tyrrhenian area the lengthening of the matera cagliari baseline should imply that convergence cannot be considered as the driving mechanism for the apenninic subduction process the estimated motion of noto is in quite good agreement with the estimated motion of the african plate

association of earthquakes and faults in the san francisco bay area using bayesian inference bayesian inference provides a method to use seismic intensity data or instrumental locations together with geologic and seismologic data to make quan titative estimates of the probabilities that specific past earthquakes are associated with specific faults probability density functions are constructed for the location of each earthquake and these are combined with prior probabilities through bayes theorem to estimate the probability that an earthquake is associated with a specific fault results using this method are presented here for large preinstrumental his torical earthquakes and for recent earthquakes with instrumental locations in the san francisco bay region the probabilities for individual earthquakes can be summed to construct a probabilistic frequency magnitude relationship for a fault segment other applications of the technique include the estimation of the probability of back ground earthquakes that is earthquakes not associated with known or considered faults and the estimation of the fraction of the total seismic moment associated with earthquakes less than the characteristic magnitude results for the san francisco bay region suggest that potentially damaging earthquakes with magnitudes less than the characteristic magnitudes should be expected comparisons of earthquake locations and the surface traces of active faults as determined from geologic data show sig nificant disparities indicating that a complete understanding of the relationship be tween earthquakes and faults remains elusive

variability of displacement at a point implications for earthquake size distribution and rupture hazard on faults abstract to investigate the nature of earthquake magnitude distributions on faults we compare the interevent variability of surface displacement at a point on a fault from a composite global data set of paleoseismic observations with the variability expected from two prevailing magnitude frequency distributions the truncated exponential model and the characteristic earthquake model we use forward modeling to predict the coefficient of variation cv for the alternative earthquake distributions incorporating factors that would effect observations of displacement at a site the characteristic earthquake model with a characteristic magnitude range of 0 25 produces cv values consistent with the data cv 0 5 only if the variability for a given earthquake magnitude is small this condition implies that rupture patterns on a fault are stable in keeping with the concept behind the model this constraint also bears upon fault rupture hazard analysis which for lack of point specific information has used global scaling relations to infer variability in average displacement for a given size earthquake exponential distributions of earthquakes from m 5 to the maximum magnitude give rise to cv values that are significantly larger than the empirical constraint a version of the model truncated at m 7 however yields values consistent with a larger cv 0 6 determined for small displacement sites although this result allows for a difference in the magnitude distribution of smaller surface rupturing earthquakes it may reflect in part less stability in the displacement profile of smaller ruptures and or the tails of larger ruptures online material global surface displacement data and identified sources of uncertainty

the length to which an earthquake will go to rupture abstract using a database of 22 historical strike slip surface rupture earthquakes an apparent upper limit is observed in the number of steps through which an earthquake is likely to rupture the number of ruptures is also observed to decrease as a function of the number of steps through which the respective earthquakes propagated the observations may be important for assessing the expected length of earthquake ruptures where fault sections interact on mapped fault systems

probabilistic models for earthquakes with large return periods in himalaya region determination of the frequency of large earthquakes is of paramount importance for seismic risk assessment as large events contribute to significant fraction of the total deformation and these long return period events with low probability of occurrence are not easily captured by classical distributions generally with a small catalogue these larger events follow different distribution function from the smaller and intermediate events it is thus of special importance to use statistical methods that analyse as closely as possible the range of its extreme values or the tail of the distributions in addition to the main distributions the generalised pareto distribution family is widely used for modelling the events which are crossing a specified threshold value the pareto truncated pareto and tapered pareto are the special cases of the generalised pareto family in this work the probability of earthquake occurrence has been estimated using the pareto truncated pareto and tapered pareto distributions as a case study the himalayas whose orogeny lies in generation of large earthquakes and which is one of the most active zones of the world has been considered the whole himalayan region has been divided into five seismic source zones according to seismotectonic and clustering of events estimated probabilities of occurrence of earthquakes have also been compared with the modified gutenberg richter distribution and the characteristics recurrence distribution the statistical analysis reveals that the tapered pareto distribution better describes seismicity for the seismic source zones in comparison to other distributions considered in the present study

strain rates in northwestern italy from spatially smoothed seismicity 1 this work presents seismic strain rate maps for the western alps and northern apennines northern italy as derived from an earthquake catalog collecting both historical and instrumental data strain rates are calculated on the basis of the rate of seismic moment release using the anderson method unlike previous applications which determined the total strain rate associated with specific seismogenic sources we have employed an innovative zoneless approach based on a spatially smoothed seismicity method in addition a monte carlo simulation procedure is applied to allow for uncertainty in the input data e g magnitude to moment conversion seismogenic thickness maximum earthquake magnitude strain rate maps are developed by summing the moments of the earthquakes reported in the catalog and by using two different earthquake recurrence relations our results indicate that deformation rates are quite high ranging from about 2 to 12 10 9 yr 1 in the northern apennines and from 0 5 to 6 10 9 yr 1 in the western alps these values however are 1 order less than those derived from global positioning system measurements suggesting that a portion of the recent deformation in northwestern italy is related to aseismic processes the discrepancies between seismic and geodetic strain rates may also indicate that the record of seismicity may not provide a sufficient time window for assessment of secular rates of moment release or secular deformation rates and rates of recurrence of large magnitude earthquakes in the study area

implications of fault slip rates and earthquake recurrence models to probabilistic seismic hazard estimates abstract increasingly fault slip rates are being used to constrain earthquake recurrence relationships for site specific probabilistic seismic hazard ground motion assessments this paper shows the sensitivity of seismic hazard assessments to variations in recurrence models and parameters that incorporate fault slip rates two models are considered to describe the partitioning of the slip rate or seismic moment rate into various magnitude earthquakes an exponential magnitude distribution and a characteristic earthquake distribution assuming an exponential distribution the activity rate n m 0 is constrained by the upper bound magnitude m u the b value for the region and the fault slip rate s for a given s variations in m u and b value have significant effects on recurrence and computed hazard depending on whether the assumption is made that the seismicity rate is constant or the moment rate is constant there is increasing evidence that the characteristic earthquake model is more appropriate for individual faults than the exponential magnitude distribution based on seismicity data from areas having repeated large earthquakes a generalized recurrence density function is developed and the resulting recurrence relationship requires only m u b value and s a comparison of the recurrence relationships from this model with the historical seismicity and paleoseismicity data on the wasatch and san andreas faults shows a good match the computed hazard based on the characteristic earthquake model differs from that obtained for the exponential model as a function of the fault to site distance and the acceleration level one check on the recurrence models using slip rate is to compare over large regions activity rates based on seismicity data and slip rate data such a comparison in the western transverse ranges shows a reasonable match for both the exponential and characteristic earthquake models in the moderate to large magnitude range

seismic gaps and recurrence periods of large earthquakes along the mexican subduction zone a reexamination abstract seismic gaps and recurrence periods of large shallow interplate earthquakes along the mexican subduction zone are reexamined after combining information from a catalog of nineteenth century9s earthquakes some relocated epicenters of the early part of this century source parameters of recent large earthquakes and redetermined magnitudes of great shallow earthquakes of this century tehuantepec and michoacan gaps have not experienced a large shock in this century and perhaps none in the past century they are either aseismic or have anomalously large repeat times guerrero jalisco and ometepec regions presently appear to have a high seismic potential observed average repeat times of large earthquakes m s 7 4 in six regions east central and west oaxaca san marcos petatlan and colima are between 32 to 56 yr data of this century indicate that the strain is released mostly in large events m s 7 4 a simple dislocation model with parameters obtained from the studies of recent earthquakes explains the observed recurrence periods quite well the b value for this zone is not meaningful an observation which is of significance for seismic risk estimation most of seismic moment or equivalently seismic energy release since 1800 appears to occur for 15 yr followed by relative quiescence in the next 15 yr

palaeoseismicity studies on end pleistocene and holocene lake deposits around basle switzerland summary palaeoseismological investigations in the lakes of seewen and bergsee in the basle region switzerland and southern germany revealed characteristic event horizons in an otherwise uniform background sedimentary record dated and correlated based on radiocarbon ages palynostratigraphy and sedimentation rates some of these event horizons show soft sediment deformation features and fractures that can be interpretated as being the result of earthquake shaking two of the event horizons with clear indications for earthquake deformation were detected in both lakes showing approximately the same age as indicated by radiocarbon dating a third event horizon with fractures of apparent seismogenic origin was detected at several drill sites in only one lake bergsee three further event horizons two in the bergsee and one in lake seewen are of uncertain origin though they show some characteristics that could well be caused by earthquakes based on the observations in both lakes five events were detected of which three are most probably related to earthquakes which occurred between 180 bc 1160 bc 8260 bc 9040 bc and 10 720 bc 11 200 bc respectively the basle region is well known for the strongest historical earthquake north of the alps the ad 1356 basle earthquake based on combined historical and palaeoseismological data it has been inferred that earthquakes with size comparable to the ad 1356 basle earthquake have occurred several times within the last 12 000 yr and that the recurrence time for such strong earthquakes are in the range of 1500 3000 yr

fault trace complexity cumulative slip and the shape of the magnitude frequency distribution for strike slip faults a global survey summary we examine whether the shape of the magnitude frequency distribution for strike slip faults is described by the gutenburg richter relationship log n a bm or by the characteristic earthquake model by analysing a data set of faults from california mexico japan new zealand china and turkey for faults within regional seismic networks curves of the form log n yrpl a bm where n yr is the number of events per year equal to magnitude m are fit to the instrumental record of seismicity and geological data are used to estimate independently the size and recurrence rate of the largest expected earthquakes that would rupture the total length of the fault extrapolation of instrumentally derived curves to larger magnitudes agrees with geological estimates of the recurrence rate of the largest earthquakes for only four of the 22 faults if uncertainties in curve slope are considered and significantly underestimates the geological recurrence rates in the remaining cases also if we predict the seismicity of the faults as a function of fault length and slip rate and the predicted seismicity is distributed in accord with the gutenburg richter relationship we find the predicted recurrence rate to be greater than the observed recurrence rates of smaller earthquakes along most faults if individual fault zones satisfy the gutenburg richter relationship over the long term our observations imply that during the recurrence interval of the largest expected earthquakes the recurrence of lesser sized events is not steady but rather strongly clustered in time however if the instrumental records provide an estimate of the long term rate of small to moderate earthquakes along the faults our observations imply that the faults generally exhibit a magnitude frequency distribution consistent with the characteristic earthquake model also we observe that the geometrical complexity of strike slip faults is a decreasing function of cumulative strike slip offset the four faults we observe to be consistent with the gutenburgrichter relationship are among those characterized by the least amount of cumulative slip and greatest fault trace complexity we therefore suggest that the ratio of the recurrence rate of small to large earthquakes along a fault zone may decrease as slip accumulates and the fault becomes smoother

earthquake rate analysis abstract earthquake rate analysis explores the quantitative relationship between earthquake occurrence rates and geological deformation rates one application is the estimation of tectonic deformation rates from seismicity for comparison with tectonic models another application is the use of geological models to help quantify seismic hazards seismicity is described by a catalog of the largest earthquakes in the region the contribution of small earthquakes towards causing geological deformation is insignificant although the occurrence rate of small events may be predictable from the occurrence rate of large events by a b value relationship the critical information about each earthquake is its seismic moment or better still its seismic moment tensor when moment is not available directly it can be estimated from the earthquake magnitude although this increases uncertainties considerably the average annual moment from all the earthquakes in the catalog is the seismic moment rate uncertainties in seismic estimates of moment rate arise from the short time period of observations from the magnitude moment relationship from the shape of the distribution function giving number of earthquakes as a function of magnitude and from uncertainties in the physical properties of the earth near the source geological models for deformation rates are described by slip rates on individual faults or by regional strain rates a regional strain rate can be derived as a limiting case where there are numerous individual faults such a strain rate is a particularly useful concept where information about each of the faults is limited in the case of either faulting or regional strain the average seismic moment rate is proportional to the deformation rate geological uncertainties arise from difficulties in estimating slip rates or strain rates from fault creep and other aseismic deformation from uncertainty in the part of the fault that fails during earthquakes and boundaries of the deforming region and from uncertainty about the earth s physical properties the seismic moment rate is the critical factor for relating the earthquake occurrence rate and the geological deformation rate using this intermediate parameter one can infer earthquake occurrence rates from deformation rates or infer deformation rates from earthquake occurrence rates generally it is found that deformation rates and earthquake occurrence rates are consistent within uncertainties where both are well constrained they are generally consistent within a factor of two or three

displacement and geometrical characteristics of earthquake surface ruptures issues and implications for seismic hazard analysis and the process of earthquake rupture there now exist about three dozen historical earthquakes for which in vestigators have constructed maps of earthquake rupture traces accompanied by de scriptions of the coseismic slip observed along the fault strike the maps and slip distributions are compiled here to place observational bounds on aspects of seismic hazard analysis and fault mechanics analysis leads to an initial statistical basis to predict the end points of rupture and the amount of surface slip expected at sites along the strike during earthquakes on mapped faults the observations also give support to the ideas that there exists a process zone or volume of about 3 4 km in dimension at the fronts of large laterally propagating earthquake ruptures within which stress changes may be sufficient to trigger slip on adjacent faults and that the ultimate length of earthquake ruptures is controlled primarily by the geometrical complexity of fault traces and variations in accumulated stress levels along faults that arise due to the location of past earthquakes to this may be added the observation that the form of earthquake surface slip distributions is better described by asymmetric rather than symmetric curve forms and that earthquake epicenters do not appear to correlate in any systematic manner to regions of maximum surface slip observed along strike online material maps of surface ruptures digitized values and curve fits to surface slip distributions and notes and references for tables 1 and 2

evaluating quaternary activity versus inactivity on faults and folds using geomorphological mapping and trenching seismic hazard implications abstract the incorporation of active faults in seismic hazard analyses may have a significant impact on the feasibility design and cost of major engineering projects e g nuclear facilities dams especially when located in the site vicinity the regulatory definition of active versus inactive fault is generally based on whether the fault has ruptured or not after a specific chronological bound i e fault recency this work presents a methodology mainly based on geomorphological mapping and trenching for determining whether specific faults can be considered as active or inactive the approach is illustrated through the analysis of several faults located in the spanish pyrenees loiti leyre la trinidad ruesta faults the 29 km long loiti thrust was included in the neotectonic map of spain as a probable neotectonic structure previous works based on geomorphological investigations incorporated the 28 km long leyre thrust as a significant seismic source in a probabilistic seismic hazard analysis which challenged the seismic design of nearby large dams the production of detailed geomorphological strip maps along the faults allowed the recognition of specific sites where the faults are covered by quaternary deposits the establishment of chronosequences pediments terrace sequences and the available geochronological data helped identifying the most adequate morpho stratigraphic units for satisfactorily evaluating fault activity vs inactivity the excavation of trenches at the selected sites provided unambiguous information on the presence or lack of deformation in the quaternary cover overlying the fault and the origin of scarps tectonic versus erosional trenches were also useful for collecting samples and reliably measuring the relative height of terraces overlain by thick colluvium the evidence gathered by these methods were complemented with the numerical dating of non deformed slope deposits covering a fault the analysis of the longitudinal profiles of old pediment surfaces located in the proximity of a fault the examination of a cave situated next to a fault searching for speleoseismological evidence and regional geodetic and seismotectonic data gps measurements earthquake focal mechanisms the integration of all the data and especially the trenches dug in non deformed old terrace deposits 100 ka truncating the faults indicates that the analysed faults can be considered inactive and that previous neotectonic postulations were based on non valid geomorphological interpretations

probabilistic seismic hazard analysis considering nonlinear site effect a modified method is proposed for the probabilistic seismic hazard analysis considering nonlinear site effect a case study is presented to show the hazard curves that consider the nonlinearity of the soil layers at gilroy 2 source parameters and an earthquake occurrence model are assigned to the caleveras fault which is assumed the dominant seismic source to the site a relationship between ground surface and bedrock accelerations at the site is established by recordings from three earthquake events using the program nonli3 which calculates the nonlinear responses of the soil layers to strong motions various values of standard errors of the estimated surface pga given the bedrock motions are assumed to perform a sensitivity analysis an alternative nonlinear relation is included in the case study in addition to the nonlinear models a linear response model is also performed using the same soil profile at gilroy 2 the results demonstrate that the hazard curves are sensitive to the standard error of the estimated surface pga values at the site the hazard curve may be severely distorted if the soil condition of a nonlinear site is treated inadequately the alternative nonlinear model obtained empirically from regression analysis and the linear response model are both unsuitable for the hazard assessment considering nonlinear site effect

lateral offsets and revised dates of large prehistoric earthquakes at pallett creek southern california recent excavation and new radiocarbon dates of sediments at pallett creek are the basis for new conclusions regarding the late holocene history of the san andreas fault systematic dissection of a 50 m long 15 m wide 5 m deep volume of earth centered on the fault enables documentation in three dimensions of fault patterns lateral offsets and vertical deformation associated with large earthquakes of the past the excavations expose evidence for 12 earthquakes that occurred between about 260 and 1857 a d with an average recurrence interval of about 145 years prehistoric slip events that occurred in 1720 50 1550 70 1350 50 1080 65 and 845 75 a d have lateral offsets that are comparable to those of the most recent great earthquake of 1857 thus all of these events represent earthquakes of large magnitude the lateral offsets of two other events in 935 85 and 1015 100 a d are an order of magnitude smaller and may be interpreted in several ways with regard to the size of these events the new data constrain the average recurrence interval for large earthquakes at this site to between 145 and 200 years but suggest a monotonic decrease in individual intervals to below this range during the past 900 years on the basis of these data the probability of a large earthquake with surficial fault rupture at this site is between 0 2 and 5 during 1984 and 7 and 60 by the year 2000

time intervals between characteristic earthquakes and correlations with smaller events an analysis based on a mechanical model of a fault certain correlations between characteristic events and smaller events are studied in the context of a spatially homogeneous mechanical model for a fault the model satisfies a one dimensional quasi linear wave equation in which the key nonlinearity is associated with the slipstick friction force at the interface between tectonic plates we find that the model gives rise to slipping events of all sizes the smaller events are consistent with the gutenberg richter statistical law whereas the characteristic events have a separate statistical distribution the crossover from smaller events to characteristic events coincides with a correlation length which sets the scale for clustering of smaller events before the characteristic rupture numerical results and scaling arguments relate the features of the distribution of characteristic events to the corresponding features of the distribution of smaller events as well as the length of the fault the distribution of time intervals between characteristic events has the distinguishing features of asymmetry and a finite upper cutoff the mean t and standard deviation of the time interval distribution are found to be related to features of the magnitude versus frequency distribution of smaller events and the coefficient of variation t is independent of the driving rate because this analysis relates properties of characteristic earthquakes to statistical features of smaller more numerous events as well as geometric features of the fault it may ultimately be useful for long term earthquake prediction

probabilistic seismic hazard analysis of victoria british columbia considering an active fault zone in the nearby leech river valleyprobabilistic seismic hazard analysis of victoria british columbia

effect of seismic source model parameters on the probabilistic seismic hazard assessment results a case study for the north anatolian fault zone the inputs to the probabilistic seismic hazard analysis psha contain large uncertainties regarding the seismic source model parameters therefore results may vary significantly due to subjective judgment and interpretation of the limited data the objective of this study is to show the effect of seismic source models on the hazard results by quantifying the differences in the design ground motions for different hazard levels at different locations around the north anatolian fault analysis showed the variances in the hazard results obtained by different seismic source models are closely correlated with the location of the site and hazard level additionally sensitivity of the hazard results to the uncertainties involved in each source parameter especially the source zone boundaries annual slip rate maximum and minimum magnitudes fault width b value and scenario weights are analyzed and presented to provide insight on the relative contribution of source or fault parameters to the psha results

erratum to surficial slip and rupture geometry on the beichuan fault near hongkou during the mw 7 9 wenchuan earthquake china worldwide occurrence and documentation of reverse type ruptures are sparse near hongkou the wenchuan rupture passes through the broad baisha river valley and provides excellent opportunities to trace the surface faulting in fine details for 13 km distance one of the longest continuous sections along the entire rupture in this paper we present the results of our mapping of the surface rupture in this reach based on the discontinuities in slip and geometry the rupture was divided into four sections for convenience from west to east the shenxi gou the miaoba the gaoyuan and the bajiao miao sections respectively the vertical offset is large in the shenxi gou and the bajiao miao sections locally reaching 5 6 m in maxima and generally low in the miaoba section 1 2 m or less in most places the slip gradient for vertical offset is generally 10 3 locally up to 10 1 similar to that in well documented strike slip ruptures near gaoyuan village the surface rupture con sists of two subparallel branches with the northern one exhibiting right lateral slip with minor southeast side up thrusting while the southern one is almost pure south east side up thrusting this pattern mimics the incomplete slip partitioning of oblique thrusting on parallel faults but at a local scale in addition the sense of vertical throw on these two strands is opposite to the general northwest side up thrusting of the wenchuan rupture we propose that it is likely due to the inheritance at shallow depth from the southeast dipping geological faults and that old fault zone structures can have a strong effect on the dynamic rupture by guiding the rupture propagation onto paths of preexisting though locally unfavorable dipping fault planes we also discuss the cross cutting slickenside striations observed near bajiao miao which indicated temporal rake rotation during dynamic rupture and their geological and seismological implications

can strong motion observations be used to constrain probabilistic seismic hazard estimates abstract because of the new regulatory requirements that hazards have to be estimated in probabilistic terms the number of probabilistic hazard studies conducted has recently been increasing the present study aims at defining the possibilities and limits for comparing predictions from these studies and observations comparison tests based directly on the rate of ground motion occurrences are favored over the rate of earthquake occurrences based on the properties of poisson processes the minimum time window ensuring reliable occurrence rate estimates at a site is computed and evaluated for example for ground motions with a 475 yr return period at a site a minimal 12 000 yr observation time window is required for estimating the rate with a 20 uncertainty coefficient of variation standard deviation divided by the mean these values are not dependent on the seismicity level of the regions under study an analysis of recorded ground motions at the stations of the permanent french accelerometer network shows that at best the occurrence rates can be estimated with an accuracy of 30 for very low acceleration levels 0 0001 0 001 g for the station stet the same analysis carried out at two stations with longer recording histories and located in higher seismicity regions greece and california provides ground motion levels up to 0 1 g therefore the question posed is can the results of a comparison test at low acceleration levels be generalized to higher acceleration levels even if using a ground motion prediction equation uniformly valid for a wide range of accelerations

characteristic earthquake model and seismicity around late quaternary active faults in japan a total of 172 late quaternary active fault zones in japan are examined to determine whether the gutenberg richter relationship or the characteristic earthquake model more adequately describes the magnitude frequency distribution during one seismic cycle by combining seismicity data for more than 100 active fault zones at various stages in their seismic cycles we reduced the short instrumental observation period compared to the average recurrence interval in only 5 of the active fault zones were the number of observed events equal to or larger than the number of events expected by the gutenberg richter relationship the average and median frequency ratios of the number of observed events to the number of expected events from the gutenberg richter relationship are only 0 33 and 0 06 respectively suggesting that the characteristic earthquake model more appropriately describes the magnitude frequency distribution along the late quaternary active faults during one seismic cycle moreover the larger an average slip rate is or the shorter an average recurrence interval the larger the gap in magnitude tends to be between the characteristic earthquake and the largest among other events a fault zone with a shorter average recurrence interval and or a larger average slip rate has generally produced more earthquakes in the past or is likely to be at a more mature or developed stage thus these tendencies may reflect a change in the magnitude frequency distribution related to the maturity or development of fault zones

fault behavior and characteristic earthquakes examples from the wasatch and san andreas fault zones paleoseismological data for the wasatch and san andreas fault zones have led to the formulation of the characteristic earthquake model which postulates that individual faults and fault segments tend to generate essentially same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum analysis of scarp derived colluvium in trench exposures across the wasatch fault provides estimates of the timing and displacement associated with individual surface faulting earthquakes at all of the sites studied the displacement per event has been consistently large measured values range from 1 6 to 2 6 m and the average is about 2 m on the basis of variability in the timing of individual events as well as changes in scarp morphology and fault geometry six major segments are recognized along the wasatch fault on the basis of the most likely number of surface faulting events 18 that have occurred on segments of the wasatch fault zone during the past 8000 years an average recurrence interval of 400 666 years with a preferred average of 444 years is calculated for the entire zone geologic data on the distribution of slip associated with prehistoric earthquakes and slip rates along the south central segment of the san andreas fault suggest that the m 8 1857 earthquake is a characteristic earthquake for this segment comparisons of earthquake recurrence relationships on both the wasatch and san andreas faults based on historical seismicity data and geologic data show that a linear constant b value extrapolation of the cumulative recurrence curve from the smaller magnitudes leads to gross underestimates of the frequency of occurrence of the large or characteristic earthquakes only by assuming a low b value in the moderate magnitude range can the seismicity data on small earthquakes be reconciled with geologic data on large earthquakes the characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as well

frequency moment distribution of earthquakes in the aleutian arc a test of the characteristic earthquake model the frequency moment distribution of earthquakes is derived for discrete regions of the entire aleutian arc both for segments which have ruptured in historic times and those regions which have been identified as seismic gaps this distribution is then compared to the moment of the largest event in the respective region or for gaps the largest event which is likely to occur based on a plate kinematic model of accumulated moment data for this study are based upon three data sources instrumental data are utilized for the 18 yr subsequent to the establishment of the world wide standardized seismograph network wwssn data for events of magnitude 7 and greater have been carefully collected and are presumed to be complete for the time period 1899 to present the last data set is comprised of the largest event in each region either an actual earthquake or the moment estimate based on current plate slip rates data were normalized to the recurrence time of the largest event in the respective zone in all cases the data seriously underestimate the largest moment event indicating that a characteristic earthquake model is appropriate for individual fault zones however if the data are combined for the entire arc the largest event is closely predicted this indicates that a b value model may be utilized only for regions in which there is a distribution in the size of earthquake producing faults

statistics of characteristic earthquakes statistical methods are used to test the characteristic earthquake hypothesis several distributions of earthquake size seismic moment frequency relations are described based on the results of other researchers as well as my own tests evidence of the characteristic earthquake hypothesis can be explained either by statistical bias or statistical artifact since other distributions of earthquake size provide a simpler explanation for available information the hypothesis cannot be regarded as proven

accelerating slip rates on the puente hills blind thrust fault system beneath metropolitan los angeles california usa slip rates represent the average displacement across a fault over time and are essential to estimating earthquake recurrence for probabilistic seismic hazard assessments we demonstrate that the slip rate on the western segment of the puente hills blind thrust fault system which is beneath downtown los angeles california usa has accelerated from 0 22 mm yr in the late pleistocene to 1 33 mm yr in the holocene our analysis is based on syntectonic strata derived from the los angeles river which has continuously buried a fold scarp above the blind thrust slip on the fault beneath our field site began during the late middle pleistocene and progressively increased into the holocene this increase in rate implies that the magnitudes and or the frequency of earthquakes on this fault segment have increased over time this challenges the characteristic earthquake model and presents an evolving and potentially increasing seismic hazard to metropolitan los angeles

seismic moment rates in the utah region an estimate of the long term seismicity of utah is obtained through the calculation of seismic moment rates from available geologic data on quaternary faulting the recurrence rates calculated from these geologic seismic moment rates agree well with recurrence rates estimated from historical earthquake data a return period of 80 to 190 yr for a magnitude 7 0 to 7 5 earthquake in the utah region is predicted by historical seismic and geologic data the estimation of recurrence rates from geologic data requires the use of a moment versus magnitude relationship for earthquakes characteristic of the utah region spectral studies of 19 utah earthquakes define this relationship in addition moment tensors and other source parameters are estimated for these earthquakes a resultant strain tensor for utah indicates the amount of horizontal east west extensional strain is nearly equal to the amount of vertical compressional strain in the region

revisiting the slip rate of quaternary faults in the iberian chain ne spain geomorphic and seismic hazard implications abstract the seismogenic potential of active faults for seismic hazard analyses are typically constrained using slip rates these parameters derived from numerically dated quaternary deposits and landforms have a critical impact on seismic hazard estimates with relevant societal and economic implications recently published geomorphological and paleoseismic investigations on active normal faults in the intraplate iberian chain spain based on osl ages from a now closed commercial laboratory indicate anomalously high slip rates and paleoearthquake frequencies and extremely high fluvial incision rates parameters derived from those numerical ages have been used for seismic hazard assessments at critical facilities this work revisits the chronology of quaternary deposits associated with several faults applying various geochronological methods electro spin resonance esr ams radiocarbon optically stimulated luminescence osl and u series dating the totality of the new numerical ages is markedly different from the previously published osl ages the thirteen new esr osl and u series ages are systematically between three and six times older than the previous osl ages these data strongly suggest that previous ages overestimate the activity of the faults and seismic hazard in the region the lack of validity of the revisited osl analyses is attributed to inadequate dating procedures slip rates calculated with the new numerical ages are consistent with the slip rates estimated using pliocene markers in the iberian chain and the slip rates published for other normal faults in eastern spain the new geochronological data also indicate reasonable fluvial incision rates comparable with those estimated in nearby regions the findings presented in this work have also implications for other quaternary geomorphological studies in spain based on potentially non valid osl ages