major and rare earth elements in rainwaters from japan and east china sea natural and anthropogenic sources abstract rainwater samples collected from tokyo and nearby locations in japan as well as from two locations over the east china sea have been analyzed for their rare earth elements rees and major ions the major ion compositions of these samples show the contributions of oceanic crustal and anthropogenic sources and suggest the relative importance of these sources rainwater samples collected in tokyo and chofu a town about 8 km from metropolitan tokyo have distinctly higher so42 and no3 content than in rainwater samples from the coastal area and the east china sea whereas the major ion compositions of the latter two areas are dominated by sea salt the rainwater samples also have variable ree compositions with various enrichment of light rees over heavy rees rainwater samples from chofu are significantly enriched in light rees whereas those collected in tokyo have loess or shale like ree composition rainwater from both places however has similar major ion compositions the enrichment of light rees in the chofu rainwater samples corresponds to the typical signature of an anthropogenic source the y ho ratios in these samples are all higher than average crustal values and in general increase with increasing enrichment of light rees this indicates that physical mixing of crustal and oceanic sources of the rees cannot account for the variations of the y ho ratios furthermore although the anthropogenic source of the rees is generally characterized by a high y ho ratio factors such as particle rainwater interactions ph and speciation of rees may also be responsible for the variable abundance and fractionation of rees and y ho in these rainwaters

interpretation of significant ground response and structure strong motions recorded during the 1994 northridge earthquake abstract some of the largest accelerations and velocities ever recorded at ground response and structural sites occurred during the northridge earthquake these motions are greater than most existing attenuation models would have predicted although the motions are large the correspondence between measured acceleration and damage requires further study since some sites with high acceleration experienced only moderate damage also some peak vertical accelerations were larger than the horizontal but in general they are smaller and fit the pattern observed in previous earthquakes strong motion records processed to date show significant differences in acceleration and velocity waveforms and amplitudes across the san fernando valley analysis of processed data from several buildings in the san fernando valley indicates that short period buildings such as shear wall buildings experienced large forces and relatively low inter story drift during the northridge earthquake however long period 1 to 5 sec steel or concrete moment frame buildings experienced large inter story drift for this earthquake accelerations did not always amplify from base to roof for flexible structures like the moment frame buildings but the displacements were always larger at the roof the drifts at many of the moment frame buildings were larger than the drift limit for working stress design in the building code the records from a base isolated building indicate that high frequency motion was reduced significantly by the isolators the isolators deformed about 3 5 cm which is much less than the design displacement the records from a parking structure show important features of the seismic response of this class of structure

empirical observations regarding reverse earthquakes blind thrust faults and quaternary deformation are blind thrust faults truly blind active thrust faults pose a significant seismic hazard worldwide many of these faults include blind thrusts where the propagating fault tip does not reach the earth s surface and buried faults where the geomorphic expression of the fault is obscured by subsequent sedimentation and or erosion this raises the issue of whether conventional geologic geomorphic and paleoseismic methods can be used to identify and characterize thrust faults for the assessment of seismic hazards or whether these faults sometimes are truly blind we compiled a data base of 148 worldwide moderate to large magnitude thrust reverse earthquakes to evaluate whether or not the event occurred on a fault that could have been identified prior to the earthquake on the basis of recognizable quaternary surface deformation i e a pre existing fault or fold analysis of the data shows that interplate reverse earthquakes almost always are associated with pre existing quaternary deformation that was or could have been recognized prior to the earthquake in particular most interplate reverse earthquakes are associated with an active reverse fault at the surface and or an active anticline in contrast intraplate reverse earthquakes seldom occur on faults associated with pre existing recognizable surface deformation we conclude that thrust faults can be detected in interplate regions with careful quaternary geologic and geomorphic mapping furthermore the absence of quaternary surface deformation can be used to infer the absence of an underlying active blind thrust fault in interplate tectonic settings however the data show that quaternary geologic mapping techniques alone likely are insufficient to characterize blind thrusts in intraplate regions in these areas inclusion of a floating or random earthquake may be necessary to assess earthquake hazards

the state of stress on some faults of the san andreas system as inferred from near field strong motion data we present a simple method to calculate the stress produced on an earthquake fault during rupture this method allows the complete evaluation of the stress spatio temporal history over the fault we apply this approach to study the changes in shear stress produced during four of the largest earthquakes which occurred along the san andreas fault system over the last 20 years the imperial valley earthquake of 1979 the morgan hill earthquake of 1984 the loma prieta earthquake of 1989 and the northridge earthquake of 1994 we use for this study the tomographic models of the fault rupture obtained from the inversion of the near field seismic data recorded during these earthquakes the results obtained show that the static and the dynamic stress drops vary greatly over the fault the peak values obtained for the four earthquakes studied range from about 20 to 100 mpa these high values imply that the initial shear stress level on the fault at the onset of the earthquake was high on at least a significant portion of the fault the regions of the fault which break with a high stress drop are also the regions where slip is large this suggests that most of the slip produced in a large earthquake takes place over the strong areas of the fault low slip regions tend to break with low stress drops after the earthquake the shear stress is increased over a significant portion of the fault which corresponds to low slip regions aftershock activity tends to be concentrated in these areas of stress increase the apparent strength of the fault before the earthquake that is the local shear stress increase which is required for rupture is also extremely heterogeneous the rupture velocity seems to be inversely correlated with this apparent fault strength the rupture accelerating over the weak areas of the fault and slowing down over the high strength areas

some considerations concerning seismic geomorphology and paleoseismology abstract seismic geomorphology studies landforms which developed in connection with earthquakes among them two different end members may be distinguished 1 seismo tectonic landforms including surface faults and fractures land uplift and subsidence at different scales surface bulges elongate ridges and any other permanent ground deformations directly related to tectonic stress and 2 seismo gravitational landforms such as landslides deep seated gravitational slope deformations sinkholes and fissures due to sediment compaction or liquefaction and sand blows connected with both seismic shaking and gravitational stress a clear cut distinction between the two categories of landforms is not always easy to make and in many instances not really useful while there are in many cases ground effects that might be and should be considered as simultaneous combinations of seismo tectonic and seismo gravitational processes this applies especially to surface fracturing and faulting which could be the combined result of tectonic stress stress produced by seismic shaking and gravitational stress the objective of this paper is to review selected case histories mainly from italy and the mediterranean region in order to show the importance of a comprehensive study of earthquake generated landforms for understanding the seismicity level of the area under investigation we argue that in earthquake prone areas seismic landforms often constitute typical patterns seismic landscapes whose recognition mapping and paleoseismological analysis may help in the evaluation of seismic hazards

strike slip earthquakes on quasi vertical transcurrent faults inferences for general scaling relations the recent occurrence of several large strike slip earthquakes provides the opportunity to review and complement available data on the scaling of seismic moment mo with length of rupture l for large earthquakes depending on their tectonic setting and mechanism for strike slip earthquakes on quasi vertical transcurrent faults the mo versus l relation has a significant change of slope around mo 0 6 0 8 1020 n m and for larger earthquakes mo scales linearly with l this is compatible with models where slip is controlled by the width of the fault also it appears to be easier to categorize large earthquakes by their mechanism strike slip on vertical transcurrent fault versus pure thrust normal than their tectonic setting interplate intraplate

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

comparison of subtropical surface water chemistry between the large pearl river in china and small mountainous rivers in taiwan abstract small mountainous rivers in oceania typically have higher sediment yields than larger rivers because of their steep gradients and frequent tropical storm induced high rainfall the high sediment yields of these small mountainous rivers enable them to transport a large amount of terrigenous material to the oceans however data are unfortunately sparse on this topic in this study we investigated the water quality and sediment geochemistry of 35 small rivers in taiwan and compared these data with that of the large pearl river although taiwan and the pearl river basin are both traversed by the tropic of cancer and thus have similar weather patterns their water chemistry is quite different the most notable difference is that despite higher rainfall in taiwan and hence a larger dilution effect the total dissolved solid concentration tds mg 2 na k cl and so 4 2 are generally higher in the taiwanese rivers compared to the pearl river on the other hand the sediment load in taiwanese rivers is higher compared with the pearl river as expected these observations reflect the higher rate of chemical weathering and denudation in taiwan due to its steeper terrain and the larger impact of typhoons hence episodic heavy rains in that region the pattern of distribution vs altitude is also different with higher tds ca 2 mg 2 so 4 2 hco 3 and ph values at higher altitudes in the pearl river basin whereas these values are lower at higher elevations in taiwan we see this difference because the upper reaches of the pearl river are primarily covered with limestone whereas the high mountains of taiwan are mainly composed of slate and schist that are more resistant to chemical weathering and less affected by acid rain compared with limestone pollution related parameters such as non sea salt so 4 2 nss so 4 2 nss so 4 na k and cl na k also suggest that rivers in taiwan are much more polluted than the pearl river basin perhaps due to the widespread burning of coal and plastic laden refuse in taiwan

source complexity of the october 1 1987 whittier narrows earthquake long and short period body waveform data recorded at regional and teleseismic distances are modeled to obtain the source parameters of the whittier narrows earthquake of october 1 1987 although the long period data can be satisfied by a simple thrust earthquake on a plane striking 280 at a depth of 14 km we require a double source solution to satisfy both the long and short period teleseismic data the first subevent has a focal mechanism of strike 250 dip 30 n and a slip vector 90 the second is 280 40 n and 98 the second event occurred 1 0 s after the first was 5 times larger 1 2 1025 dyn cm for the second 0 23 1025 for the first in terms of seismic moment and was also shallower 12 km whereas the first subevent was at 15 km the two subevents probably occurred on a north dipping listric fault but may have occurred on two subparallel faults these features were determined by studying a variety of phases including teleseismic p and sh and regional pnl the whittier narrows earthquake was a high stress drop event but a single value for stress drop cannot be obtained because of the complex nature of the source if we define the fault area as the aftershock area we obtain a stress drop of about 750 bars

ground motion prediction model from local earthquakes of the mexico basin at the hill zone of mexico city abstract we developed ground motion prediction equations gmpes based on bayesian regressions to predict response spectra at sites located in the hill zone of mexico city for local earthquakes of the mexico basin the coefficients of the gmpes are built as functions of magnitude 2 3 m w 3 8 and hypocentral distance 8 r 60 km using 15 local earthquakes we compare our results with five gmpes an attenuation model obtained in the northern region of the subduction zone in the pacific coast of mexico from small earthquakes and four other existing gmpes for shallow crustal earthquakes two of the gmpes although not the most recent ones are still used to perform probabilistic seismic hazard analysis for the region under study

studies of stress and displacement distribution and the evolution law during rock failure process based on acoustic emission and microseismic monitoring abstract the evolutions of stress and deformation inside of rock is highly important in studies of the rock failure mechanism but is difficult to obtain via the traditional stress measurement methods due to limited measuring points thus studies of the stress and displacement evolution within rock were conducted based on acoustic emission ae monitoring in laboratory experiments the differences in the distributions and evolution characteristics of the stress field and deformation field before caving in a deep stope were also examined based on in situ microseismic ms monitoring the results show that the distributions of micro cracks apparent stress and deformation inside the rock are highly consistent and can reflect the spatial temporal evolution characteristics of the stress field and deformation field within the rock the accumulated apparent volume is more accurately than the strain to reflect the changes in inelastic deformation inside the rock based on in situ ms monitoring ms activities were found to be closely related to blasting disturbances during the caving process before a caving of the deep stope the distributions of stress and displacement showed obvious differences reflecting the loosening process of the rock mass the non uniformity and the differences in the stress and deformation can deepen the understanding of the rock mass failure process

surface rupture associated with a 5 3 mb earthquake the 5 april 1986 cuzco earthquake and kinematics of the chincheros quoricocha faults of the high andes peru abstract the shallow mb 5 3 1986 earthquake that affected the cuzco region reactivated the 18 km long chincheros qoricocha faults in the central part of the cuzco fault system although the event has a moderate magnitude clear surface ruptures were observed to total 3 km in length with maximum 10 cm normal displacements fault kinematics related to the earthquake analyzed where the qoricocha fault had a maximum surface fault displacement is in agreement with roughly n s extension the normal fault mechanism proposed for this earthquake is compatible with the surface kinematic analysis seismic activity prior to the 1986 earthquake is deduced from analysis of holocene scarps trench exposures give evidence for at least three fault displacements suggesting an average recurrence interval of the order of a few thousand years for surface rupturing seismic events these fault reactivations with vertical displacement ranging from 0 6 to 2 m were related to seismic events of mw magnitude probably ranging from 5 8 to 6 9 structural analyses of holocene faults indicate that the chincheros qoricocha fault activity was related to roughly n s trending extension characterized by a horizontal n s trending 3 axis and a vertical 1 axis the n s extensional tectonics that controlled the holocene and 1986 chincheros qoricocha fault activity are the typical deformational pattern of the peruvian high andes and seem to be in agreement with compensated high topography

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

shallow intraplate earthquakes in western australia observed by interferometric synthetic aperture radar 1 we investigate two intraplate earthquakes in a stable continental region of southwest western australia both small magnitude events occur in the top 1 km of crust and their epicenters are located with an accuracy of 100 m 1 using satellite interferometric synthetic aperture radar insar for the mw 4 7 katanning earthquake 10 october 2007 the average slip magnitude is 42 cm over a rupture area of 1 km2 this implies a high static stress drop of 14 27 mpa even for this very shallow earthquake which may have important implications for regional seismic hazard assessment the earthquake rupture extends from a depth of around 640 m to the surface making it a rarely observed intraplate surface rupturing event using insar observations we estimate the coseismic slip distribution of the shallow earthquake such estimates being rarely available for small magnitude events for the mw 4 4 composite kalannie earthquake sequence 21 22 september 2005 we use a long term time series analysis technique to improve the measurement of the co seismic signal which is a maximum of 27 mm in the line of sight direction double difference seismic analysis shows some relocated cluster seismicity which corresponds in timing location and source parameters to the insar observed deformation this earthquake is the smallest magnitude seismic event to have been investigated using insar and demonstrates the capability of the technique to provide important constraints on small magnitude coseismic events the shallow depth of both these events adds weight to the suggestion that earthquakes associated with tectonic processes in this area of western australia often initiate in the upper 1 km of crust

capable faulting environmental effects and seismic landscape in the area affected by the 1997 umbria marche central italy seismic sequence abstract the september october 1997 seismic sequence in the umbria marche regions of central italy has been one of the best studied from the seismological macroseismic and geological point of view numerous papers have been published in the period immediately after the seismic sequence providing a significant database of effects triggered by the earthquake on natural environment in the following years further studies have provided additional pieces of evidence that allow to better relate the seismic sequence with its geological background moreover recent developments in the characterization of coseismic environmental effects provide new horizons in seismic hazard assessment sha procedures which should take into account even long term geomorphological and geological features resulting from repeated characteristic earthquakes concept of seismic landscape this paper reviews the current state of knowledge on the 1997 umbria marche seismic sequence with particular regard to coseismic environmental effects primary and secondary that have been used for esi seismic intensity assessment in order to verify if i they are consistent with geological seismological and macroseismic data in the location and characterization of the seismogenic structure and ii if they fit the seismic landscape features that mark the epicentral area of colfiorito

effects of chemical weathering and sorting on the petrogenesis of siliciclastic sediments with implications for provenance studies the bulk chemical compositions mineralogy and mineral proportions of sands and muds of the mallacoota basin in southeastern australia reflect the composition of weathering profiles mantling source rocks rather than bedrock muds contain abundant clay minerals that are virtually absent from the source rocks but abundant in the weathering profiles sands are strongly enriched in quartz relative to source rocks even in the headwaters of the fluvial system demonstrating that feldspar destruction occurs by in situ chemical weathering within profiles and before detritus enters the fluvial system k feldspar is proportionally more abundant in fluvial sands than in source rocks because plagioclase is more rapidly destroyed than either quartz or k feldspar in weathering profiles subsequent erosion and sorting produce sands enriched in quartz with high k feldspar plagioclase ratios relative to source rocks the composition of plagioclase incorporated into the fluvial sands is also controlled by chemical weat

fault scaling relationships deformation rates and seismic hazards an example from the lazio abruzzo apennines central italy abstract spatial variations in the number of seismic shaking events in a given time period frequency implied by measured throw rates associated with active normal faults in central italy are investigated through comparison with models of fault growth and the historical record of earthquake shaking for the region measured offsets of 18 ka glacial features provide a throw rate database averaged over a time period much longer than the reliable portion of the historical earthquake record for the region

a procedure for modelling shallow dislocation sources summary expressions for displacements on the surface of a layered half space due to an arbitrary oriented shear dislocation are given in terms of generalized ray expansions useful approximations of these expressions for shallow events as recorded at teleseismic distances for realistic earth models are presented the results of this procedure are used to generate synthetic p sv and sh waveforms for various assumptions of stress drop

fault geometry and slip distribution of the 2010 yushu earthquakes inferred from insar measurement we construct a coseismic deformation interferogram for the april 2010 yushu earthquakes using alos palsar data from the ascending track path 487 we then infer the trace of the yushu fault using the coherence image and we build five fault models for the yushu fault to determine the fault geometry parameters that give the best fit to the coseismic interferogram we apply an elastic dislocation algorithm our preferred fault model consists of two faults dipping to the northeast one strikes n60 w with a dip of 82 the other strikes n67 w with a dip of 86 lastly we infer the coseismic slip distributions of the yushu earthquakes by the inversion of the displacement in the line of sight los the results show that three high slip concentrations are located at a depth of 5 8 km with a peak slip of 1 32 m at 96 93 e 33 03 n the yushu fault is a left lateral strike slip faulting with small north side up dip slip components

moment magnitude rupture area scaling and stress drop variations for earthquakes in the mediterranean region abstract a dataset of moment magnitudes and rupture areas is compiled for 53 earthquakes that occurred in the mediterranean region during the period 1976 2013 moment magnitudes of these events range from 4 45 to 7 56 and the rupture areas are mainly inferred from the dimensions of their aftershocks zone three magnitude area relationships that have been determined using global datasets namely wells and coppersmith 1994 hanks and bakun 2002 and shaw 2009 are examined to determine how well they fit these observations the relationship of shaw 2009 exhibits the best goodness of fit to the data followed very closely by a modified version of the hanks and bakun bilinear relationship statistical tests show that the magnitude residuals of the two relationships are not significantly different thus either of them could be used for seismic hazard analysis stress drop of the selected events varies within a narrow range increasing from 1 mpa for seismic moments less than 1 10 18 n m to about 6 mpa for larger events taking into account that the majority of the events under study are either normal or strike slip earthquakes this pattern of stress drop variation is in contrast to that in areas like taiwan or the mexico subduction zone where thrust faulting is dominant for these areas earthquakes tend to exhibit larger stress drops of up to 100 mpa suggesting there is an apparent dependence of stress drop variation on faulting type online material detailed information for 53 earthquakes used to derive the magnitude rupture area scaling relation

the spatiotemporal strain partitioning across the longmen shan fault zone during seismic cycles implications for deformation mechanisms and seismicity in eastern tibet abstract we develop a two dimensional plane strain viscoelastoplastic finite element model to simulate the evolutions of displacement velocity and strain across the longmen shan lms fault zone during seismic cycles in this study we investigate strain partitioning and seismicity in eastern tibet due to purely crustal shortening lateral variations in lithospheric viscosity beneath eastern tibet the increased lower crustal flow velocity and the active longriba lrb fault our results show that the accumulated interseismic strain across eastern tibet is released mainly by the characteristic large earthquakes on the lms fault leading to prominent coseismic uplift of eastern tibet during the postseismic period eastern tibet especially the lms region continues to uplift due to viscoelastic stress relaxation in the middle lower crust and upper mantle when a stronger ahba sub block or middle lower crustal flow is considered the modeled vertical displacement and velocity in the upper crust increase largely in the lms sub block causing more rapid uplift of this region we also demonstrate that the active lrb fault would accommodate some crustal shortening repartition the strain in eastern tibet and eventually change the seismicity on the lms fault

weathering and global denudation a negative correlation between sediment yield and weathering history as measured by the chemical alteration cia of the suspended sediment is observed for many of the world s major rivers and other regions of denudation the weathering history is a first order control on the sediment yield of such areas termed equilibrium denudation regions for other areas data scatter with either apparent increases or decreases of sediment yield for given cia values these areas are termed nonequilibrium denudation regions low sediment yields can be attributed to moderated erosion either natural or human induced and or the incorporation of unweathered glacial debris accelerated erosion resulting in high sediment yield is primarily human induced and results from cultivation and other land use each of these effects has a profound influence on global sediment discharge from the continents pre human suspended sediment discharge from the continents is estimated to be 12 6 times 10 15 g yr or about 0 6 the

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

moderate chemical weathering of subtropical taiwan constraints from solid phase geochemistry of sediments and sedimentary rocks abstract the well known earthquake and storm triggered extremely high physical weathering rate in taiwan is consistent with present geochemical studies of sediments from different subenvironments offshore coastal river and lake and sedimentary rocks of different geological ages indicating a moderate chemical weathering condition major and trace element concentrations normalized to the average upper crust of yangtze craton show that the sediments and the average composition of sedimentary rocks of taiwan are depleted in ca mg na and sr enriched in rb and zr and unchanged with respect to k indicating their moderately altered nature the mean chemical index of alteration cia 71 75 and plagioclase index of alteration pia 81 86 values of coastal and offshore sediments reveal the sediments derivation from sedimentary rocks by moderate silicate chemical weathering processes the mean cia value 62 of sedimentary rocks of taiwan is similar to that for chinese sediment 61 further confirming

assessing interaction of active extensional faults from structural and paleoseismological analysis the teruel and concud faults eastern spain abstract the relationship of independence interaction or linkage between two neighbouring intraplate active extensional faults the teruel and concud faults are investigated from structural and paleoseismological data and the results are discussed to improve seismic hazard assessment for the region this paper provides the structural and paleoseismological characterization of the almost unknown teruel fault from detailed mapping and trench analysis and discusses its kinematic and dynamic relationships with the concud fault four individual events occurred between 76 0 ka and 9 2 ka bp have been recorded at two branches of the teruel fault unfortunately these only represent a small fraction of its overall activity during such time lapse and their time constraints do not allow correlating them with those at the concud fault the teruel and concud faults are independent structures from the geometric and kinematic point of view as evinced by their distinct i transport directions n275 e and n220 e respectively and ii average coseismic displacements 0 5 m and 1 9 m respectively these displacements are consistent with their respective lengths 9 0 km and 14 2 km and significantly smaller than those expected for a hypothetically joint concud teruel 23 km long fault however their displacement gradients close to the relay zone indicate that both faults undergo dynamic interaction thus suggesting a transient stage from independence to linkage we hypothesize that slip on both structures occurred at the scale of the seismic cycle in a broadly alternating manner which induced strain partitioning between them and allowed accommodating bulk biaxial extension in the region such deformation pattern would have increased the earthquake frequency with respect to the scenario of a hypothetically linked concud teruel fault but diminished the potential seismic magnitude

source spectra for the 1988 saguenay quebec earthquakes abstract source spectra are obtained for the 1988 saguenay quebec earthquake m n 6 5 its foreshock m n 4 8 and largest aftershock m n 4 1 using recordings from analog and digital seismographs on rock sites at epicentral distances from 40 to 700 km the source spectra of the foreshock and the aftershock are well matched by a single corner frequency 2 model with seismic moments of 2 2 10 22 and 2 2 10 21 dyne cm respectively and a stress parameter of 65 bars for both events by contrast the spectrum of the mainshock differs dramatically from this simple shape a stress parameter of 500 bars is required to match the observed high frequency amplitudes using the seismic moment determined from teleseismic observations as a constraint this single corner frequency model however overestimates amplitudes at frequencies near 1 hz by a factor of about 2 the relative radiation of short and long period energy for the mainshock is inconsistent with that from other intraplate earthquakes the fore and aftershocks appear typical in this regard the extraction of source spectra from the regional data required a careful examination of attenuation azimuthal variations were observed with the attenuation being most severe to the southeast normal to the st lawrence valley and the dominant structural grain of the region the st lawrence river coincides in part with the boundary between the grenville and appalachian tectonic provinces and the difference in attenuation may be related to the difference in tectonic province the distribution of data however makes it difficult to obtain good estimates of the attenuation in each province lumping the data from both provinces and the three earthquakes together results in an anelastic attenuation factor given by q 755 f 0 5 for frequencies f from 0 6 to 18 hz using data at distances r beyond 100 km from the sources and assuming 1 r geometrical spreading this attenuation is similar to that obtained in a number of other studies in the general area three component recordings were available at a few stations and from these the following frequency dependent ratio of horizontal to vertical motion was obtained hiv 1 14 0 118 f 0 00638 f 2 for frequencies from 0 2 to 15 hz different methods of correcting observations for attenuation in order to derive source spectra were examined source spectra derived by simple regression analyses of observed data assuming a uniform medium are very similar to those based on a more complicated synthetic seismogram correction which accounts for wave propagation in a layered earth

scaling of ground motion parameters state of stress and focal depth the ground motion parametersrv and ra where r is hypocentral distance v is peak velocity is density and a is peak acceleration are found observationally to be strong functions of stress state and linearly related to focal depth z if the stress state and focal depth are properly taken into account then the ground motion parameters depend on the seismic moment m0 as expected from basic scaling principles that is rv m01 3 and ra is independent of earthquake size regression lines fitted to observations covering broad ranges in seismic moment and focal depth indicate that for extensional and compressional tectonic regimes corresponding to normal and thrust or reverse faulting earthquakes respectively peak acceleration is given by ra 1 08 mpa 3 06 mpa km z normal and ra 5 65 mpa 8 76 mpa km z thrust and for peak velocity rv m01 3 10 4 m2 s n m 1 3 3 00 0 69 km 1 z normal and rv m01 3 10 4 m2 s n m 1 3 4 63 1 82 km 1 z thrust for strike slip earthquakes the data currently are insufficient to define regression fits but such lines would definitely lie between those for the normal and thrust stress regimes these equations are appropriate for ground motion at small hypocentral distance as recorded in a whole space it follows that for comparable hypocentral depth peak acceleration in a compressional tectonic regime for example much of the eastern united states is a factor of about 3 greater than in an extensional regime such as nevada and for peak velocity a similar comparison yields a factor of 2 difference the similarity in behavior of the peak acceleration parameter to crustal strength estimated from byerlee s law of friction with respect to depth and stress state indicates that crustal strength is probably the factor governing the seismic source processes that give rise to the high frequency peak ground motion analysis of the peak acceleration data in the context of crustal strength suggests bounds on this ground motion parameter as recorded at a typical surface site that depend on stress state specifically a normal 0 5 g and a thrust 1 9 g thus the state of stress as well as the focal depth clearly is an important factor to be taken into account in the prediction of seismic ground motion

source complexity of the 1994 northridge earthquake and its relation to aftershock mechanisms we determined the source process of the 1994 northridge earthquake in relation to the aftershock mechanisms to study the source complexity of the mainshock we inverted the p and sh waveforms recorded by the iris and ida iris networks using the method of kikuchi and kanamori 1991 in which the rupture is represented by a series of discrete subevents with varying mechanisms the waveforms show that the rupture consisted of several subevents with about 2 sec in between our solution consists of three subevents with essentially the same mechanism viz strike dip and slip of 130 42 and 116 respectively the first subevent occurred at a depth of about 19 km followed after 2 sec by the second and largest subevent at a depth of 17 km and the third subevent again 2 sec after the second at a depth of about 13 km the total moment from the body waves of this sequence is about 1 1 10 26 dyne cm m w 6 6 with a source duration of 7 sec the large depths of these subevents explain the lack of any surface rupture furthermore the upward propagation of the subevents is consistent with the depth of the hypocenter and the distribution of the aftershocks which are shallower and more northerly than the mainshock hypocenter the aftershocks were analyzed using data from the terrascope network we inverted short period surface waves to determine the moment tensor for 70 events with m w 3 5 the aftershocks can be grouped into three regions based on the mechanisms the eastern part of the aftershock zone where we find thrust events with mechanisms very similar to the main event a central area with predominantly strike slip events and an area to the west where we find oblique thrust events but with more northerly p axes than in the eastern region this distribution suggests that the fault system on which the northridge earthquake occurred is segmented and that the extent of the northridge rupture is controlled by a change in geometry of the fault we find a high stress drop 270 bar for the mainshock we propose that the changes in the fault geometry prevented a slip pulse from propagating thereby causing a high ratio of slip to rupture length

source parameters of the 1980 mammoth lakes california earthquake sequence from the more than 1500 mammoth lakes earthquakes recorded on three component digital seismographs spudich et al 1981 150 were used in an analysis of the locations mechanism and source parameters a composite fault plane solution of nine earthquakes 3 9 m 5 1 defines a right lateral strike slip mechanism on a steeply dipping nearly east west plane striking s75 e or left lateral strike slip on a nearly north south plane striking n10 e vertical cross sections of well located aftershocks indicate possibly three east west planes that coincide with the locations of the four largest earthquakes with ml 6 0 using the spectral analysis of s waves brune 1970 source parameters for 67 earthquakes were determined forty eight had magnitudes greater than or equal to 3 0 seismic moments ranged from 9 20 1018 dyn cm to 2 33 1024 dyn cm earthquakes with seismic moment greater than about 1 0 1021 dyn cm had nearly constant stress drops 50 bars earthquakes with seismic moment less than about 1 0 1021 dyn cm had stress drops that apparently decrease as seismic moment decreases

the 13 january 2001 el salvador earthquake a multidata analysis 1 on 13 january 2001 a large normal faulting intermediate depth event mw 7 7 occurred 40 km off the el salvadorian coast central america we analyze this earthquake using teleseismic regional and local data we first build a kinematic source model by simultaneously inverting p and sh displacement waveforms and source time functions derived from surface waves using an empirical green s function analysis in an attempt to discriminate between the two nodal planes 30 trenchward dipping and 60 landward dipping we perform identical inversions using both possible fault planes after relocating the hypocentral depth at 54 km we retrieve the kinematic features of the rupture using a combination of the neighborhood algorithm of sambridge 1999 and the simplex method allowing for variable rupture velocity and slip we find updip rupture propagation yielding a centroid depth around 47 km for both assumed fault planes with a larger variance reduction obtained using the 60 landward dipping nodal plane we test the two possible fault models using regional broadband data and near field accelerograms provided by universidad centro americana 2001 near field data confirm that the steeper landward dipping nodal plane is preferred rupture propagated mostly updip and to the northwest resulting in a main moment release zone of approximately 25 km 50 km with an average slip of 3 5 m the large slip occurs near the interplate interface at a location where the slab steepens dip significantly the occurrence of this event is well explained by bending of the subducting plate

source parameters of the bay of bengal earthquake of 21 may 2014 and related seismotectonics of 85 e and 90 e ridges abstract source parameters of the bay of bengal earthquake of 21 may 2014 have been studied using full waveform inversion its source mechanism thus determined the orientation of the strike slip faulting as nw se ne sw the occurrence of past earthquakes along the ne sw nodal plane suggested its preference as the main fault which could result from the transmission of stresses from the indian plate boundary high stress drop of this earthquake 216 bar is attributed to its location in the intraplate region strike slip faulting and focus in the colder upper mantle comparison of the stress drop of deeper focus hindukush earthquakes with that of the bay of bengal earthquake showed a smaller felt radius due to fractured lithosphere in the himalayas vis a vis more efficient propagation of seismic waves in the peninsular region from the source region of this recent earthquake the seismological evidence presented for the 85 e and 90 e ridges shows the predominance of strike slip faulting with thrusting on both the ridges integrating their source mechanism with that of the may 2014 earthquake it could be inferred that the bay of bengal region excluding andaman sumatra subduction zone is characterised predominantly by strike slip faulting in the region north of latitude 20 n and strike slip with thrusting in the remaining portion

future trends in paleoseismology integrated study of the seismic landscape as a vital tool in seismic hazard analyses this paper forms the introduction to this special issue of tectonophysics devoted to selected scientific research presented during events sponsored by the inqua subcommission on paleoseismicity in the past few years in this note we summarize the contents of the contributed papers and use the issues they raise to review the state of the art in paleoseismology from a quaternary geology perspective in our opinion the evolution of paleoseismological studies in the past decade clearly demonstrates that in order to properly understand the seismic potential of a region and to assess the associated hazards broad based multidisciplinary studies are necessary to take full advantage from the geological evidence of past earthquakes a major challenge in future paleoseismic research is to build detailed empirical relations between various categories of coseismic effects in the natural environment and earthquake magnitude intensity these relations should be compiled in a way that is fully representative of the wide variety of natural environments on earth in terms of climatic settings quaternary tectonic evolution rheological parameters of the seismogenic crust and stress environment for instance available data indicate that between earthquake magnitude and surface faulting parameters different scaling laws exist and they are a function of the local geodynamic setting including style of faulting typical focal depths heat flow in this regard we discuss in some detail the concept of seismic landscape which provides the necessary background for developing paleoseismological research strategies the large amount of paleoseismological data collected in recent years shows that each earthquake source creates a signature on the geology and the geomorphology of an area that is unequivocally related with the order of magnitude of its earthquake potential this signature is defined as the seismic landscape of the area e g serva l vittori e ferreli l michetti a m 1997 geology and seismic hazard in grellet b mohammadioun b hays w eds proceedings of the second france united states workshop on earthquake hazard assessment in intraplate regions central and eastern united states and western europe october 16 1995 nice france 20 24 ouest editions nantes france michetti a m hancock p l 1997 paleoseismology understanding past earthquakes using quaternary geology

helium isotope ratios in easter microplate basalts abstract 3 he 4 he ratios in easter microplate basalt glasses show clear evidence of the effects of a mantle plume the east rift of the microplate between 26 and 28 s identified by la sm sr and pb isotopes and ridge crest elevation as the region of maximum plume influence has 3 he 4 he ratios spanning the entire range from 7 5 to 11 7 r a the easter microplate is the only section of the entire east pacific rise that is associated with a known hotspot track mantle plume and has elevated 3 he 4 he ratios although most of the west rift basalts contain morb helium 8 0 8 7 r a the basalt closest to the east rift has an elevated 3 he 4 he ratio 11 3 r a consistent with a significant plume component the diversity in isotopic signatures also indicates that homogenization of isotopic anomalies does not occur even in this region of super fast spreading the overall 3 he 4 he 206 pb 204 pb and 3 he 4 he 87 sr 86 sr trends have positive correlations although the high 3 he 4 he 87 sr 86 sr and 206 pb 204 pb component is not a single value but rather a broad band the apparent decoupling between the he and sr isotope distribution is modeled in the context of a plume source migrating ridge sink during channeling of the plume toward the ridge helium is preferentially lost from the center of the channeled plume resulting in lower he pb and he sr concentration ratios in the high 3 he 4 he component mixing trajectories in he sr isotopic space between a lile depleted asthenosphere and a variably degassed plume component provide a reasonably good fit to the data and may explain the isotope systematics of plume ridge interactions in the context of modern theories of plume dynamics

inversion of source parameters and site effects from strong ground motion records using genetic algorithms the low frequency flat levels and corner frequencies of the aftershocks of the kobe earthquake together with the site effects of the recording stations are inverted by using genetic algorithms all records were corrected by the quality factor q of propagation path and for each aftershock a different omega squared model was assumed such that the low frequency flat levels and corner frequencies would minimize the standard deviation of the site effects at all stations it was observed that site effects for rock sites showed significant amplification at high frequencies this amplification was found to correlate with spectral ratios of records located at 70 m depth and at the surface for one of the stations after estimating the seismic moment and the stress drop it was observed that the relation of the seismic moment m0 versus the corner frequency fo followed the scaling law m0 fo 3 large values of stress drop were found around asperities on the fault zone and at depth

the muzaffarabad pakistan earthquake of 8 october 2005 surface faulting environmental effects and macroseismic intensity the mw 7 6 muzaffarabad earthquake of 8 october 2005 occurred on a lateral equivalent of the main ramp of the hymalaia frontal thrust and is the result of the collision tectonics between the indian and eurasian plates the epicentre was located near the town of basantkot muzaffarabad and the focal depth was about 13 km the muzaffarabad earthquake provides unequivocal evidence about the localization of severe damage intense ground shaking and secondary environmental effects near the surface expression of the source fault we analyse its nature and impact on man made structures and the physical environment on the basis of a detailed survey and macroseismic study of the affected areas conducted by the micro seismic studies programme mssp team ishfaq ahmad research laboratories pakistan atomic energy commission immediately after the mainshock assisted by a careful review of the subsequent data and literature in the course of the field survey the displacement and surface expression of the causative fault and accompanying secondary environmental effects were observed at a number of places along a capable thrust fault structure we refer to this structure as the kashmir thrust kt capable fault following the terminology of local research geologists in pakistan the seismological evidence of this structure is already known in the literature as the indus kohistan seismic zone a complex clearly segmented at least 112 km long surface rupture was mapped along the kt the maximum values of vertical displacement on the order of 4 to 7 m were observed mainly between muzaffarabad and balakot along the central segment of the rupture 52 km associated with maximum slip at depth and a major portion of the energy release both the nw alai segment 38 km and se bagh segment 22 km are characterized by scattered minor surface ruptures with a few centimetres of displacement accompanied by extensive surface cracking landslides and severe damage concentrated in a narrow belt along the fault trace a maximum intensity of xi on the modified mercalli intensity mmi scale and on the environmental seismic intensity scale esi 2007 was recorded in the epicentral area between muzaffarabad and balakot extremely severe damage and very important secondary environmental effects in the hanging wall adjacent to the trace of the causative fault plane are mainly due to near fault strong motion and rupture directivity effects to our knowledge this is the first study to present field observations over the whole near field of the earthquake and to include the intensity map of the entire meizoseismal region the geological society of london 2009

evaluation of elemental enrichments in surface sediments off southwestern taiwan surface slices of 20 sediment cores off south western taiwan and bed sediment of river kaoping were measured for major and trace elements al as ca cd cl cr cu fe k mg mn na ni p pb s si ti v and zn to evaluate the geochemical processes responsible for their distribution including elemental contamination major element al ratio and mean grain size indicate quartz dominated coarse grained sediments that likely derived from sedimentary rocks of taiwan and upper crust of yangtze craton bi plot of sio2 versus fe2o3 suggests the possible iron enrichment in sediments of slag dumping sites highest concentrations of cr mn p s and zn found in sediments of dumping sites support this correlation analysis shows dual associations detrital and organic car bon for cr p s and v with the latter association typical for sediments in dumping sites normalization of trace elements to al indicates high enrichment factors 2 for as cd pb and zn revealing contamination factor analysis extracted four geochemical associations with the principal factor accounted for 25 1 of the total variance and identifies the combined effects of dumped iron and steel slag induced c s fe relationship owing to authigenic precipitation of fe mn oxyhydroxides and or metal sul fides and organic matter complexation of fe mn ca cr p and v factors 2 3 and 4 reveal detrital association ti al ni pb cu and v effect of sea salt cl mg na and k and anthropogenic component as and zn carbonate link respectively in the investigated sediments

spatial and temporal variation of palaeoseismic activity at an intraplate historically quiescent structure the concud fault iberian chain spain abstract several faults in the teruel and jiloca grabens iberian chain ne spain particularly the targeted concud fault show evidences of recent continuous activity despite their scarce instrumental and historic seismic record three trenches are studied in two locations central and southeastern sectors of the concud fault respectively after comparing with previous works we reconstruct a palaeoseismic succession with nine events distributed along a maximum time lapse bracketed between 81 6 and 14 0 ka this succession involves an average recurrence interval of 7 4 2 8 ka with individual interseismic periods between 4 and 11 ka the calculated coseismic displacements range from 0 6 to 2 7 m with an average value of 1 9 m that results in a slip rate of 0 26 mm a due to the incomplete sedimentary record for holocene times we cannot affirm that the youngest event detected was actually the last one we conjecture that some other events may have occurred during the period between 15 0 and 3 4 ka temporal and spatial variations have been detected in palaeoseismic activity specifically in the distribution of coseismic displacements first a non steady slip rate is evidenced during plio pleistocene times a long term tendency towards increasing slip rate is modulated in detail by the occurrence of minor cycles as the sequence of increasing decreasing activity recorded within the studied time window suggests secondly an asymmetric distribution of coseismic slip along the fault trace is observed paralleling the distribution of total fault throw which shows an absolute maximum close to the southeastern tip a combination of factors is proposed to explain this branching of the main fault dominant remote stress driven slip towards n 220 e on the nw se fault segment guided movement on the passive nnw sse segment giving rise to an oblique roll over monocline and decoupling of the hanging wall block owing to the transverse los mansuetos valdecebro fault zone

paleoseismological analysis of an intraplate extensional structure the concud fault iberian chain eastern spain the concud fault is a 13 5 km long nw se striking normal fault at the eastern iberian chain its recent late pleistocene slip history is characterized from mapping and trench analysis and discussed in the context of the accretion incision history of the alfambra river the fault has been active since late pliocene times with slip rates ranging from 0 07 to 0 33 mm year that are consistent with its present day geomorphologic expression the most likely empirical correlation suggests that the associated paleoseisms have potential magnitudes close to 6 8 coseismic displacements of 2 0 m and recurrence intervals from 6 1 to 28 9 ka at least six paleoseismic events have been identified between 113 and 32 ka the first three events u to w involved displacement along the major fault plane the last three events x to z encompassed downthrow and hanging wall synthetic bending prompting fissure opening this change is accompanied by a decrease in slip rate from 0 63 to 0 08 0 17 mm year and has been attributed to activation of a synthetic blind fault at the hanging wall the average coseismic displacement 1 9 2 0 m and recurrence period 6 7 7 9 ka inferred from this paleoseismic succession are within the ranges predicted from empirical correlation such paleoseismic activity contrasts with the moderate present day seismicity of the area maximum instrumental mb 4 4 which can be explained by the long recurrence interval that characterizes intraplate regions

changes in frequency size relationship from small to large earthquakes the constant b value observed in frequency magnitude distributions of earthquakes has been taken as an indication of self similarity at all magnitudes hence earthquake properties should scale uniformly in the same way from small to large earthquakes it has often been observed however that the seismic moment released in small earthquakes scales differently with rupture length than it does for large events1 2 where the crossover between small and large events is defined at a rupture dimension equal to the down dip width of the seismogenic zone a possible explanation for this contradiction is that frequency size distributions are biased by small earthquakes small events dominate most global earthquake catalogues because of the short time period covered another source of bias in size distributions is the saturation of earthquake magnitudes for large events here we correct biases in calculations of b values and present evidence for a change in b value in frequency size distributions we find that a break in self similarity from small to large earthquakes occurs at a point where the dimension of the event equals the down dip width of the seismogenic layer

stress drop slip type earthquake magnitude and seismic hazard care must be taken to provide reliable antiseismic protection in earthquake prone areas where the impact of a large earthquake in megacities with industrial facilities as well as in ordinary buildings is liable to cause massive loss of human life and to cripple the nation s economy this protection needs to take into account not only vibratory ground motion but also permanent ground failure and notably surface faulting hazard a fact tragically illustrated during the recent events of turkey and taiwan the purpose of this contribution is to conduct a survey of our current state of knowledge concerning theoretical relationships between earthquake source parameters such as moment magnitude m m w surface wave magnitude m s seismic moment m o stress drop rupture length l and displacement on the fault d a relationship is proposed that links m s to l and m s 2 log l 1 33 log 1 66 using a simple rupture model earthquake data from all over the world for which the parameters of rupture length fault width w fault displacement and surface wave magnitude are available have enabled stress drop values to be computed for each event using both geological observation 1 and the previously proposed equation 2 the results obtained tend to indicate that stress drop values increase versus fault width depth up to approximately 15 km corresponding perhaps to the brittle ductile boundary this increase is more pronounced in the case of reverse faults than it is for those with strike slip or normal mechanisms an equation of the type kw n has been used to fit the data and preliminary values for k and n have been supplied for the three slip types for depths in excess of 15 km the data do not display significant variation 100 bars these results are in agreement with certain laboratory models of the continental lithosphere although more data particularly in the large magnitude range are needed to ascertain whether it is the w or the l model that better describes earthquake scaling laws stress drop does not appear to be fault length dependent thus being supportive of the l model the risk of surface faulting is dependent on the dynamic environment of the fault that is the stress drop the rupture length and the fault width although statistics show that surface faulting appears in most instances at magnitudes of at least 6 1 data from certain regions indicate that seismicity at superficial depths is under certain conditions accompanied by significant surface faulting even for magnitudes as small as 5 5 suggesting a change in scaling law the threshold magnitude for surface faulting is accordingly seen to depend on the rheology of materials in the fault area and on the stress environment manuscript received 31 may 2000

upper mantle heterogeneities and dynamics the width of geochemical and residual elevation anomalies along the mid ocean ridge system decrease as both the distance between migrating ridge segments and related hotspots and the local geochemical dispersion in the anomalies increase these observations provide further evidence that flows of mantle plumes in the upper mantle are deflected by migrating ridge sinks once they override hotspots

comparison of source scaling relations of eastern and western north american earthquakes source scaling relations have been obtained for earthquakes in eastern north america and other continental interiors and compared with a relation obtained for earthquakes in western north america the scaling relation for eastern north american earthquakes was constructed from measurements of seismic moment and source duration obtained by the waveform modeling of seismic body waves the events used include nine events of m blg magnitude 4 7 to 5 8 that occurred after 1960 and four earlier events with magnitudes between 5 5 and 6 6 the scaling relation for events in other continental interiors was used for comparative purposes and to provide constraints for large magnitudes detailed analysis of the uncertainties in the scaling relations has allowed the resolution of two important issues concerning the source scaling of earthquakes in eastern north america first the source characteristics of earthquakes in eastern north america and other continental interiors are consistent with constant stress drop scaling and are inconsistent with nonconstant scaling models such as that of nuttli 1983 second the stress drops of earthquakes in eastern north america and other continental interiors are not significantly different from those of earthquakes in western north america and have median values of approximately 100 bars the source parameters of earthquakes in eastern north america are consistent with a single constant stress drop scaling relation whereas the source parameters of earthquakes in western north america are much more variable and show significant departures from an average scaling relation in which stress drop decreases slightly with seismic moment

multi element geochemistry of sediments from the pearl river system china sediment samples were taken along the west north and east rivers of the pearl river system at 28 locations in 1998 and a total of 49 elements were determined by icp aes icp ms and inaa the probability features of the datasets were studied and the average concentrations of these elements in sediments of the three rivers were calculated significant differences in element concentrations among the three rivers were observed and the results were confirmed by statistical tests including analysis of variance anova kruskal wallis test and t test spatial distribution maps of element concentrations were produced using a geographical information system gis the immobile trace elements such as sc ti v cr mn fe co and ni are enriched in the west river where limestone dominates the rock types in the watershed because of the strong weathering immobile trace elements are enriched and reside in secondary minerals of the weathering products all three rivers have high concentrations of rare earth elements rees because of strong weathering but relatively higher concentrations of rees are observed in sediments of the east river where granite dominates the rock type granite contains high concentrations of rees and the sediments have inherited this feature from their bedrock alkaline element li na k rb and cs concentrations are elevated in sediments of the east river these may reside in granitic primary minerals relatively high concentrations of alkaline earth elements mg ca sr and ba are observed in the west river inherited from the limestone bedrock high pb and bi concentrations are found in the north river and are caused by pb mineralization and the discharge of a smelter in the upper reaches of the river however statistical tests did not indicate a significant difference between pb concentrations in the north river and the other two rivers which suggests that statistical results should be carefully used and explained

a methodology for seismic loss estimation in urban regions based on ground motion simulations seismic vulnerability assessment of residential buildings in regions of high seismicity is an interdisciplinary problem requiring major inputs from fields of seismology and earthquake engineering the basic two components of loss estimation methods are information on regional seismicity and building stock this study presents a realistic loss estimation methodology where the first component input ground motions is obtained from regional ground motion simulations using the stochastic finite fault technique the second component building vulnerability information on the other hand is taken into account using fragility analyses introducing the ground motion intensity parameters obtained from simulations to the fragility curves we obtain seismic loss distribution in a region in this study we demonstrate the loss estimation methodology with an application to three northwestern cities in turkey duzce bolu and kaynasli that experienced two major earthquakes graphic 1 and graphic 2 in less than three months in 1999 we initially verify the methodology with comparisons of observed and estimated damage ratios for the 12 november 1999 graphic 3 duzce earthquake later we present the estimated damage ratios under scenario earthquakes in the region for a magnitude range of graphic 4 graphic 5 is predicted to be the threshold magnitude for the cities of duzce and kaynasli where more than 60 of the building stock experience moderate and heavy damage because bolu is at a farther distance from the fault plane less damage is estimated for graphic 6 than those in the other centers for graphic 7 all three cities are predicted to experience substantial rates of heavy damage and collapse 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif 4 embed inline graphic 4 gif 5 embed inline graphic 5 gif 6 embed inline graphic 6 gif 7 embed inline graphic 7 gif

climatic and tectonic controls on weathering in south china and indochina peninsula clay mineralogical and geochemical investigations from the pearl red and mekong drainage basins 1 results of clay mineralogy major element geochemistry and sr and nd isotopes in 93 argillaceous samples collected from drainage basins of the pearl red and mekong rivers reveal different degrees of chemical weathering in southeast asia despite similar climate conditions across these regions the kaolinite illite ratio illite chemistry index and illite crystallinity can be used as indicators of chemical weathering intensity these mineralogical proxies combined with the k2o na2o cao molar ratio chemical index of alteration cia and weathering trends observed from major element results indicate intensive silicate weathering in the pearl river basin moderate to intensive in the mekong river basin and moderate in the red river basin although a significant modification of epsilon nd 0 values in our riverine sediments during chemical weathering and transport is unlikely sr 87 sr 86 ratios are controlled by various states of chemical weathering of high sr minerals such as plagioclase rich in na and ca with a linear decrease trend from the pearl mekong to red river basins our results suggest that it is not the warm climate with heavy monsoon precipitation but tectonics playing the most significant role in controlling weathering and erosion processes in south china and indochina peninsula strong physical erosion caused by tectonic activities and river incision along the eastern margin of the tibetan plateau and along the red river fault system is responsible for high contents of primary minerals in the lowlands of red and mekong river basins

detrital fine grained sediment contribution from taiwan to the northern south china sea and its relation to regional ocean circulation article i nfo results of clay mineralogy in 140 samples collected in major rivers and lakes in southwestern taiwan and on the seafloor off taiwan in the northeastern south china sea scs combined with clay mineral records of the pearl river drainage basin rivers in luzon and the south china shelf and slope are used to semi quantitatively evaluate the detrital fine grained sediment contribution of taiwan to the northern scs the clay mineral assemblage of the taiwan sourced sediments consists dominantly of illite average 56 and chlorite 41 with very scarce kaolinite and smectite their respective distribution from the rivers and lakes to the seafloor off taiwan does not show obvious basin wide differences linear correlations of illite chemistry index with illite crystallinity and of illite crystallinity with kaolinite present two end members of provenances the pearl river and taiwan for the south china shelf and slope assuming that kaolinite in the northern scs is provided completely from the pearl river the contribution of taiwan in clay minerals is evaluated as 29 to the south china shelf and 23 to the south china slope respectively accordingly the contribution of the pearl river to the south china shelf and slope is 52 and 31 respectively the luzon arc accounts for the rest of clay mineral components for the northern scs mainly by providing smectite the bashi strait crossed branches of the southward deep north pacific deep water and the northward surface kuroshio current in the western pacific may transport taiwan sourced suspended sediments westwards to the northern scs

correlation of sedimentary units from grain size and mineralogic analyses as a tool for constraining trench interpretations in palaeoseismology in palaeoseismological trench studies precise correlation of sedimentary units between fault blocks has an unquestionable value for accurately inferring the amounts of coseismic displacement and hence for assessing seismic hazard a methodology based on laser analysis of particle size and mineralogic composition by x ray diffraction is proposed in order to strengthen the correlation of sedimentary units in a trench excavated across the concud fault central iberian chain spain the surveyed sediments show sharp and multiple lateral facies changes as well as inconsistent optically stimulated luminescence osl ages the results reinforce the correlation based on field inspection of lithologic and sedimentologic features moreover they allow interpretation of rejuvenation of osl ages of samples in the upthrown fault block which has been attributed to partial erosion of sedimentary units as evidenced by their smaller thickness and erosive boundaries the correlated units are then used to estimate coseismic displacements for three palaeoseismic events

earthquake hazard and the environmental seismic intensity esi scale the main objective of this paper was to introduce the environmental seismic intensity scale esi a new scale developed and tested by an interdisciplinary group of scientists geologists geophysicists and seismologists in the frame of the international union for quaternary research inqua activities to the widest community of earth scientists and engineers dealing with seismic hazard assessment this scale defines earthquake intensity by taking into consideration the occurrence size and areal distribution of earthquake environmental effects eee including surface faulting tectonic uplift and subsidence landslides rock falls liquefaction ground collapse and tsunami waves indeed eees can significantly improve the evaluation of seismic intensity which still remains a critical parameter for a realistic seismic hazard assessment allowing to compare historical and modern earthquakes moreover as shown by recent moderate to large earthquakes geological effects often cause severe damage therefore their consideration in the earthquake risk scenario is crucial for all stakeholders especially urban planners geotechnical and structural engineers hazard analysts civil protection agencies and insurance companies the paper describes background and construction principles of the scale and presents some case studies in different continents and tectonic settings to illustrate its relevant benefits esi is normally used together with traditional intensity scales which unfortunately tend to saturate in the highest degrees in this case and in unpopulated areas esi offers a unique way for assessing a reliable earthquake intensity finally yet importantly the esi scale also provides a very convenient guideline for the survey of eees in earthquake stricken areas ensuring they are catalogued in a complete and homogeneous manner

local earthquakes of the mexico basin in mexico city κ q source spectra and stress drop abstract we analyzed 14 local earthquakes of the mexico basin 2 3 m w 3 8 recorded on hill sites at local distances 8 0 r 60 5 km to study the spectral attenuation of seismic waves spectral decay parameter kappa quality factor q source spectra and brune stress drop we found an average 0 value of 0 0457 s in hill sites which is similar to values reported in other regions assuming a 1 r geometrical spreading we obtain a quality factor given by q f 72 f 0 83 source spectra of all studied events are in good agreement with the 2 model from the synthetic modeling of ground motions at local distances we explain an anomalous behavior of the corner frequency versus seismic moment and also explain the relatively low values observed for stress drop 5 mpa the resulting high spectral attenuation values obtained may be responsible for the low acceleration values of ground motions observed for crustal earthquakes occurring inside and near to the mexico basin

volcanic and seismic hazards at a proposed nuclear power site in central java abstract a nuclear power plant site has been proposed near the base of mount muria a long dormant volcano in indonesia over a period of eight years the volcanic and seismic hazards were investigated first by the contractor and later by a joint team of indonesian geologists and consultants to the international atomic energy agency in order to assess the risk posed by a large volcano for which there is no record of historical eruptions it was necessary to determine the age of the last activity by geological and geochronological means and to deduce from this whether the volcano posed a credible risk similarly because there was no adequate record of seismic activity the seismic hazards were investigated mainly by geological geomorphological and geophysical methods that identified and characterized potential seismogenic sources related to the volcano or tectonic movements i e active capable faults muria volcano has not erupted since about two thousand years ago but the last activity was sufficiently recent to rule out any assumption that the volcano is extinct detailed studies indicated that the proposed site may be vulnerable to the effects of air borne tephra pyroclastic flows and surges debris flows lahars and opening of new vents a more serious factor however was the poor geotechnical properties of the foundation material that required a careful analysis of the seismic hazards although the project was suspended the study proved useful because it provided an opportunity to develop procedures and techniques that could be applied in similar studies elsewhere