shrimp zircon u pb dating of quartz porphyry from zhongjia tin polymetallic deposit in longyan area fujian province and its geological significance mineralizations of the zhongjia tin polymetallic deposit in longyan area of fujian province are composed of vein type ore bodies in the external contact zone and veinlet disseminated sn wo mineralization in the inner contact zone belonging to post magmatic hydrothermal type related to quartz porphyry of the area shrimp u pb dating of twenty zircon grains from the quartz porphyry gived the weighted mean age of 98 5 1 7 ma n 29 mswd 1 8 suggesting that the quartz porphyry in the deposit was produced by regional tectono magmatic activities during the late stage of early cretaceous tin polymetallic mineralization of the zhongjia deposit occurred in late cretaceous instead of in early jurassic and constituted a part of late yanshanian metallogenic activity on the margin of the south china tungsten tin and polymetallic province as evidenced by regional metallogenic correlation the authors hold that the prospecting targets of tin polymetallic deposits in southwestern fujian province should be late yanshanian granitic bodies and their external contact zones

mapping geochemical anomalies related to fe polymetallic mineralization using the maximum margin metric learning method abstract geochemical anomaly identification is an important task in mineral exploration targeting this task can be regarded as a binary classification problem whereby the aim is to discriminate between anomalous and not anomalous i e background we can analyze geochemical data from the aspects of frequency distributions correlations and variances geometrical properties of geochemical anomalies and scale independence of geochemical patterns in this study we recognize geochemical anomalies based on the intrinsic relationship between geochemical elements which can be addressed by measuring their separation distance as a machine learning method metric learning aims at exploiting the statistical information between the geochemical features in limited training samples and developing a more suitable distance to evaluate the similarity of samples without priori distribution assumptions accordingly a metric learning method based on the maximum margin frame was applied to identify multivariate geochemical anomalies related to fe polymetallic mineralization in the southwestern fujian province of china the geochemical exploration data were firstly translated into a dimensional reduced subspace with the help of maximum margin metric learning mmml the adaptive coherence estimator ace detector from the field of target detection was then employed to identify geochemical anomalies the anomaly results obtained by this integrated procedure using a combination of mmml and ace were compared to those obtained by ace without metric learning using a receiver operating characteristic roc curve the area under the curve value implied superior performance using the combination of mmml and ace suggesting that this hybrid method can be effectively applied to recognize geochemical anomalies linked to mineralization

three dimensional finite difference simulation of long period ground motions for the 2003 tokachi oki japan earthquake 1 to explore the generation and propagation mechanisms of long period ground motions we used a 3 d finite difference method to simulate wave propagation during the 2003 mw 8 3 tokachi oki japan earthquake a large scale computation with an inverted slip model and a geological and geophysical based velocity structure model successfully reproduced the overall characteristics of substantial observed velocity seismograms for a period range of 3 3 to 25 s significant long period ground motions of extended duration were observed in the yufutsu basin where oil tanks were damaged at tomakomai because of sloshing associated with the ground motions our simulation revealed that the combination of the large and shallow earthquake and the deep extent of the sedimentary basin generated long period ground motions with a duration of several hundred seconds the yufutsu basin contains an internal subbasin that deepens from east to west in contrast with the geometry of the overall basin that deepens from west to east the long period ground motions were amplified in both the eastern and western parts of the basin with the durations being greatly extended in the western part a series of computations with and without each of the velocity layers within the basin demonstrated that the basin response amplifies long period ground motions as expected and that the subbasin response is effective in amplifying and extending long period ground motions our quantitative 3 d finite difference simulations clarify the generation of disastrous long period ground motions that occurred in the yufutsu basin during the 2003 tokachi oki earthquake

a hot water ice coring drill a new method of ice core drilling uses an annulus of hot water jets to melt out a cylindrical ice core this lightweight device used in combination with a fast hot water drill can quickly obtain ice cores from any depth

borehole response studies at the garner valley downhole array southern california the garner valley downhole array gvda consists of a set of seven downhole strong motion instruments ranging from 0 to 500 m depth one of the objectives of this experiment is to estimate site response and study wave propagation as the energy travels from the bedrock underneath the site up through the soil column the gvda velocity structure is studied by computing synthetic accelerograms for a small event located at an epicentral distance of 10 km these synthetics simulate well the data recorded at the borehole stations in addition theoretical transfer functions are calculated using the obtained velocity model and compare well with the empirical transfer functions from 54 recorded events it is also observed that the downgoing wave effect is predominant in the first 87 m and is strongly reduced at depth using the velocity structure at gvda and the transfer function results it has also been possible to develop a simple method to compute the incident wave field which is needed in nonlinear site response for instance recently there have been many comparative studies between horizontal to vertical h v spectral ratios and traditional spectral ratios although many of these studies show that h v spectral ratios can reproduce the shape of the site response curve most show differences in the amplitude level in the case of garner valley where we have both surface and multiple borehole instruments we find that this discrepancy in amplitude of the site response estimates is because the vertical component has significant site response associated with it due to s to p conversions that begin in the weathered granite boundary at 87 m depth manuscript received 27 august 2001

locating spatial changes of seismic scattering property by sparse modeling of seismic ambient noise cross correlation functions application to the 2008 iwate miyagi nairiku mw 6 9 japan earthquake

earthquake induced snow avalanches i historical case studies strong ground motions caused by earthquakes can induce catastrophic avalanches massive snow avalanching has also been observed on slopes near quarries and underground mines where ground motions are produced by explosives to address a lack of information regarding seismogenic snow avalanches we have compiled an inventory to document case histories for the period 1899 2010 22 cases are identified worldwide related to natural or artificial seismicity with magnitudes of 1 9 mw 9 2 and source to site distances of 0 2 640 km in the extreme case many thousands of simultaneously released large scale avalanches have been reported the obtained distribution and variety of parameters are discussed and compared with earthquake induced landslides and ice avalanches the results are similar among these three types of failure events although all data derived from statistical analyses i e non witnessed cases represent outliers suggesting a significant reduction in the threshold magnitudes proposed for landslides this proposal could be verified by the collection of additional data

accounting for source effects in the shakemap procedure the 2000 tottori and the 2008 miyagi earthquakes italian presidenza del consiglio dei ministri dipartimento della protezione civile dpc under the contract 2007 2009 dpc ingvs3project

decomposing of mixed pattern of arsenic using fractal model in gangdese belt tibet china abstract decomposing mixed geochemical patterns is a challenge in geochemical exploration and environmental assessment in this paper the spectrum area technique s a is used to decompose a mixed pattern of arsenic in gangdese belt based on stream sediment data s a is a multifractal model based on power law relationships between area of the set consisting of wave numbers with spectral energy density above s a s on the 2d frequency domain the original spatial distribution map of arsenic obtained by inverse distance weighted idw shows a mixed pattern due to superposition of different geological processes or events and is converted into the frequency domain by means of fourier transformation two components including power spectrum density and phases are obtained the spectrum energy density s and the area a enclosed by the above threshold spectrum energy density is plotted on a log log scale two cutoff values determined by three straight lines define three filters which decompose the original map of arsenic into background anomalous and high frequency noise components the areas with high anomaly of arsenic mainly are located surrounding known cu deposits indicating that arsenic anomalies may be related to cu mineralization

nonlinear soil behavior examined on the basis of propagation time observed at the kik net ichinoseki nishi vertical array abstract the iwate miyagi nairiku earthquake 14 june 2008 m 7 2 depth 8 km caused severe damage in the southern part of iwate and the northern part of miyagi prefectures in japan the kik net ichinoseki nishi vertical array site iwth25 operated by the national research institute for earth science and disaster prevention nied is situated near the epicenter the observed peak ground accelerations at the surface in the up down east west and north south directions were respectively 3866 cm s 2 1432 cm s 2 and 1143 cm s 2 the extreme ground motions recorded at this site provide valuable information about the wave propagation and soil degradation at a large strain level we examined the nonlinear soil behavior at the site due to the earthquake on the basis of normalized input output minimization niom analysis first we analyzed 279 records observed before the iwate miyagi nairiku earthquake and estimated the vertical propagation time initial value between the bottom of the well and the ground surface by taking into account incidence angles then we analyzed the records of the iwate miyagi nairiku earthquake and 179 events that occurred after it from 14 june 2008 to 19 october 2009 the results revealed that 1 the s wave propagation time increased from 0 265 s to about 0 35 s because of the nonlinear behavior of the soil 2 this propagation time change corresponded to a 60 reduction in the shear moduli of the upper soil layers surface to 64 m depth and a strain level of 1 10 3 3 a gradual decrease in the propagation time with decreasing seismic intensity was observed soon after the principal motions however 4 the propagation times in the coda part and for the events after the iwate miyagi nairiku earthquake were still larger than the initial value indicating that the shear rigidities of soils remained less than their values before the earthquake for more than a year

nonlinear ground motion amplification by sediments during the 1994 northridge earthquake it has been known since at least 1898 ref 1 that sediments can amplify earthquake ground motion relative to bedrock for the weak ground motion accompanying small earthquakes the amplification due to sediments is well understood in terms of linear elasticity hooke s law 2 but there has been a long standing debate regarding the amplification associated with the strong ground motion produced by large earthquakes the view of geotechnical engineers based largely on laboratory studies is that hooke s law breaks down at larger strains causing a reduced nonlinear amplification seismologists on the other hand have tended to remain sceptical of this nonlinear effect mainly because the relatively few strong motion observations seemed to be consistent with linear elasticity although some recent earthquake studies have demonstrated nonlinear behaviour under certain circumstances3 4 the significance of nonlinearity for the type of stiff soil sites found in the greater los angeles region remains unresolved5 here we report that ground motion amplification due to sediments for the main shock of the 1994 northridge earthquake was up to a factor of two less than the amplification observed for its aftershocks these observations imply significant nonlinearity in such amplification and bring into question the use of measurements of weak ground motion to predict the strong ground motion at sedimentary sites

translating the mineral systems approach into an effective exploration targeting system abstract holistic mineral systems approaches are being increasingly adopted in the study of ore deposits but application in industry has been suboptimal because of the lack of a conceptual framework to help translate the mineral system understanding to practical application a four step process is proposed for linking the conceptual mineral system with data available to support exploration targeting these steps include translation from 1 critical processes of the mineral system to 2 constituent processes of the mineral system to 3 targeting elements reflected in geology and 4 targeting criteria used to detect the targeting elements directly or by proxy this translation process is illustrated using examples from komatiite hosted ni cu pge and orogenic au mineral systems ranking of targets must be at the critical process level rather than the current practice of mixing processes elements and proxies the significance of targeting elements and their mappable criteria changes as a function of the scale at which the critical processes operate and the availability of relevant geoscience datasets this scale dependence is rarely recognised in current practice sources of uncertainty when translating the mineral system understanding into an effective exploration targeting system include 1 resolution of a mappable criterion in a dataset 2 how well the targeting criterion reflects the targeting element 3 how well the targeting element reflects the critical process and 4 whether the process being mapped is critical for the genesis of a mineral deposit the first three sources of uncertainty collectively are termed the representativeness of the targeting criteria i e how representative is a mappable criterion of the constituent process for which it is a proxy the last source of uncertainty reflects our lack of understanding of the processes that control mineralisation and highlights areas for further research

application of fuzzy logic and geometric average a cu sulfide deposits potential mapping case study from kapsan basin dpr korea abstract in this paper two kinds of knowledge driven methods one using the fuzzy logic and another using geometric average were applied to create the mineral potential maps for cu sulfide deposits in the greenfield kapsan basin dpr korea the ore geology studies for the study area have revealed that cu sulfide deposits of hydrothermal genesis in kapsan basin are closely associated with jurassic intrusions and faulting tectonics based on the conceptual model of cu sulfide deposits and the available spatial datasets in the study area we used five independent evidential maps for cu sulfide deposits potential mapping they include 1 faults 2 aeromagnetic anomaly 3 cu geochemical data 4 pb geochemical data and 5 zn geochemical data the evidential map values were transformed into continuous values of the 0 1 range using the non linear fuzzy membership functions logistic sigmoid and fuzzy gaussian functions because the fuzzy logic and geometric average methods can use the same fuzzification methodology based on suitable membership functions it is very economic and efficient to simultaneously apply two predictive models for mineral potential mapping of the study area the preparation of these evidential layers were performed using spatial analyses supported in arcgis 10 4 gis platform based on geological geophysical and geochemical spatial datasets the validation and comparative analysis results for the two predictive models demonstrated that most of known mineral occurrences are distributed in areas with high potential values the target areas classified by the fuzzy logic occupy 15 of the study area and contain 78 of the total number of known mineral occurrences compared with the fuzzy logic the resulting areas by the geometric average occupy 13 of the study area but contain 93 of the total number of known mineral occurrences although the total number of known mineral occurrences is relatively low for the application of roc receiver operating characteristics technique the areas under the roc curve auc obtained by two predictive models were greater than 0 5 suggesting that both predictive models and their resulting potential maps are useful for evaluating the prospectivity of cu sulfide deposits in kapsan basin

effects of misclassification costs on mapping mineral prospectivity abstract mineral prospectivity mapping is a classification process because in a given study area a specific region is classified as either a prospective or non prospective area the cost of false negative errors differs from the cost of false positive errors because false positive errors lead to wasting much more financial and material resources whereas false negative errors result in the loss of mineral deposits traditional machine learning algorithms using for mapping mineral prospectivity are aimed to minimize classification errors and ignore the cost sensitive effects in this study the effects of misclassification costs on mapping mineral prospectivity are explored the cost sensitive neural network csnn for minimizing misclassification costs is applied to map fe polymetallic prospectivity in china s southwestern fujian metalorganic belt sfmb a csnn with a different cost ratio ranging from 1 10 to 10 1 was used to represent various misclassification costs the cross validation results indicated a lower misclassification cost compared to traditional neural networks through a threshold moving based csnn the csnn s predictive results were compared to those of a traditional neural network and the results demonstrate that the csnn method is useful for mapping mineral prospectivity the targets can be used to further explore undiscovered deposits in the study area

recognition of geochemical anomalies using a deep variational autoencoder network abstract deep learning dl algorithms have received increased attention in various fields in the field of geoscience dl has been shown to be a powerful tool for mining complex high level and non linear geospatial data and for extracting previously unknown patterns related to geological processes in this study a deep variational autoencoder vae network was used to extract features related to mineralization and these features were then integrated as a anomaly map in support of mineral exploration based on geochemical exploration data which consist of cu pb mn zn and fe2o3 various experiments were conducted to determine the optimal parameters of the vae the structure of the vae in which the network depth and number of hidden units were 24 12 3 12 24 was built to recognize geochemical anomalies related to fe polymetallic mineralization in the southwest fujian province china the geochemical anomalies recognized by the vae show a close spatial correlation with known fe polymetallic deposits meanwhile the areas with high probability are located in or around the yanshanian intrusions and the contact zones of the carboniferous permian formation and yanshanian intrusions these results suggest that the anomalous areas identified by the vae are meaningful for mineral exploration

influence of a sedimentary basin infilling description on the 2 d p sv wave propagation using linear and non linear constitutive models numerical modelling is a useful tool to understand the role of different parameters site geometry impedance contrast material properties constitutive model input motion governing site effects we focus here on the 2 d p sv seismic wave propagation in a simple shaped asymmetric model we consider two ways of describing the sedimentary infilling properties the basin is either composed of distinct homogeneous geological layers or is described through properties progressively changing as a function of depth smooth model in order to study the wave propagation in the two basins with similar soil properties p and s velocities of the layered basin are deduced from the smooth basin ones making both models compatible in a kinematic point of view p and s velocities globally increase with depth following epri non linear properties are considered as constant in layers for the two basins we assess the influence of the model choice on the wave propagation while taking into account linear and non linear constitutive models we test the influence of the input motion by propagating two different input motions the first being a simple impulsive one and the second a real complex accelerogram we find that transfer functions computed in each basin are quite similar irrespective of the soil constitutive behaviour and the input motion moreover we show that the maximum shear strain spatial distribution depends on the input motion frequency content and maximum values depend on the input motion strength and complexity maximum shear strains are generally higher for superficial layers than for deeper ones we show that the highest shear strain values are located above discontinuities where velocities are lower and the soil is more non linear than in the underlying layer regardless of the input motion indeed in a layered basin the shear strain is higher above interfaces for all the soil constitutive models that were used in the smooth visco elastoplastic model a kind of layering appears absent in a viscoelastic model due to the different non linear properties in each layer moreover no matter what the model structure and the input motion used maximum shear strain levels are higher in the visco elastoplastic soil than in the viscoelastic one such a numerical study helps to understand the non linearity location and therefore the consequences of a model choice when performing a site specific study

episodic seafloor mud brecciation due to great subduction zone earthquakes the nankai trough off southwest japan has an 1300 yr historical record of great earthquakes including the most recent the a d 1944 tonankai m 8 2 earthquake evaluation of the activity of an individual submarine fault is difficult when only onland observations are available submarine core records can pinpoint individual fault activity here we present integrated ocean drilling program iodp nankai trough seismogenic zone experiment data from the shallow portion iodp expedition 316 drilled and cored several holes in the shallow portion of the offshore tonankai earthquake area including sites in the hanging wall of a margin dominating splay fault that has previously been interpreted to have ruptured coseismically during megathrust earthquakes x ray computed tomography scanning revealed that the uppermost core at one site contains repeated occurrences of mud breccia radioisotope dating of the uppermost mud breccia indicates a deposition time consistent with the 1944 tonankai earthquake suggesting that the mud breccia layers result from episodic brecciation caused by seismic shaking mud brecciation provides a potential new tool to reconstruct ancient earthquake history in subduction zones

inversion of strain dependent nonlinear characteristics of soils using weak and strong motions observed by borehole sites in japan during the 1995 hyogo ken nanbu earthquake strong motions with horizontal peak ground accelerations of 507 cm sec 2 or more 187 cm sec 2 and 126 cm sec 2 were observed at surface stations of borehole sites at amagasaki takasago and nanko in japan respectively we showed qualitative evidence of nonlinear soil response during strong motions at amgasaki and takasago but not at nanko using cross correlation and spectral ratio analyses of weak and strong motions we evaluated soil nonlinearity by inversion for s wave velocities and frequency dependent damping factors the strain dependence of shear modulus ratios inverted for gravel is larger than that for clay which is consistent with laboratory test results in the shear strain range from about 10 4 to 10 3 the strain dependence of shear modulus ratios inverted for clay and gravel at amagasaki and takasago is consistent with empirical relations based on laboratory test results for clay and gravel respectively these results support using laboratory estimates of shear modulus ratios to simulate strong motions at clay and gravel sites the damping factors for gravel inverted from the mainshock at amagasaki are the largest among the others but the strain dependence of damping factors are not as significant as that of shear modulus ratios the reason why the strain dependence of damping factors is not so significant may be because scattering attenuation is relatively dominated in the low strain range

the mineralization age of the makeng fe deposit south china implications from u pb and sm nd geochronology the makeng fe deposit is located in the southwestern fujian district south china the sm nd isochron ages of seven samples of pure garnet and five of pure magnetite separates from the makeng ores yielded an isochron age of 157 15 ma laser ablation inductively coupled plasma mass spectrometry la icp ms zircon u pb dating of the nearby exposed the dayang juzhou dj porphyritic biotite granite and fine grained syenogranite yielded 206pb 238u ages of 140 2 1 1 and 140 1 1 0 ma respectively these results suggest that the intrusion of the dj granite and the makeng skarn alterations and fe mineralization are contemporaneous the dj granite exhibits geochemical characteristics of a type granites including high values of na2o k2o 8 13 8 92 wt feot mgo 3 4 21 5 and ga al 2 64 3 45 10 4 and low al2o3 10 71 13 29 wt value chondrite normalized rare earth element patterns are characterized by obviously negative eu anomalies eu 0 02 0 28 and primitive mantle normalized spidergrams show the enrichment in high field strength element and depleting in sr ti ba and eu the geochemical characteristics of dj granite suggest that the granite was derived from partial melting of the paleoproterozoic metasedimentary rocks of the cathaysia basement and some underplating of mafic magma in the lower tholeiitic crust and or depleted mantle might be involved and provide the heat source for the partial melting the dj granite also fits the spatiotemporal distribution of the jurassic cretaceous coastward migration of both extensional and arc related magmatism and fills the a type granites gap in the early stage of the early cretaceous 145 125 ma therefore it is suggested that the late jurassic and early cretaceous magmatism in southwestern fujian district were generated in an extensional environment responding to the slab rollback and concomitant retreating arc system of the paleo pacific plate within the south china block and the fe metallogeny in southwestern fujian district is genetically linked with the magmatism during this period

a comparative study of two modes for mapping felsic intrusions using geoinformatics abstract identifying felsic intrusions is an essential task in support of mineral exploration because the intrusions can be a source of energy and metals for magmatic hydrothermal mineralization in this paper two models for mapping felsic intrusions are compared based on regional geochemical and geophysical data geochemical data as a type of compositional data which carry relative information should be preprocessed using log ratio transformation the first model a factor ratio f2 f1 model was developed based on the chemical characteristics of the felsic intrusions which are rich in k2o and high field strength elements f2 but poor in fe2o3 and compatible elements f1 the second model a hybrid model that combines principal component analysis and local singularity analysis was based on the chemical and physical properties of the felsic intrusions the results showed that 1 raw geochemical data should be processed using log ratio transformation prior to multivariate data analysis to avoid spurious correlations between variables and 2 the hybrid model performed better than the ratio of factors model for inferring felsic intrusions in the study area the felsic intrusions mapped in this study provide information that can support further mineral exploration in the dong ujimqin fe cu polymetallic district inner mongolia northern china

hysteretic and dilatant behavior of cohesionless soils and their effects on nonlinear site response field data observations and modeling in this study we present evidence that nonlinearity can be directly observed in acceleration time histories such as those recorded at the wildlife refuge and kushiro port downhole arrays from the 1987 superstition hills california and the 1993 kushiro oki japan earthquakes respectively these accelerograms and others compiled in this study present a characteristic waveform composed of intermittent high frequency peaks riding on a low frequency carrier in addition soil amplification of the surface records is strongly observed compared to their downhole counterpart this is contrary to the expected amplification reduction produced by the nonlinear soil behavior laboratory studies show that the physical mechanism that produces such phenomena is the dilatant nature of cohesionless soils which introduces the partial recovery of the shear strength under cyclic loads this recovery translates into the ability to produce large deformations followed by large and spiky shear stresses the spikes observed in the acceleration records are directly related to these periods of dilatancy and generation of pore pressure these results are significant in strong motion seismology because these spikes produce large if not the largest acceleration they are site related not source related using the in situ observations from the kushiro port downhole array we have modeled the 1993 kushiro oki earthquake the synthetic accelerograms show the development of intermittent behavior high frequency peaks as observed in the recorded acceleration time histories shear modulus degradation due to pore pressure produces large strains in the soil with large amplification in the low frequency band of the ground motion we also modeled data from the 1987 superstition hills earthquake recorded at the wildlife refuge station the results show the importance of better soil characterization when pore pressure may develop and the effects of dilatancy in the understanding of nonlinear site response

sensitivity analysis of prospectivity modeling to evidence maps enhancing success of targeting for epithermal gold takab district nw iran abstract the takab metallogenic province in the northwestern iran hosts a number of gold resources including carline like and epithermal type mineralization these occurrences are hosted by tectonized country rocks of precambrian basement metamorphic rocks and tertiary volcanic and sedimentary units which are intruded by the intrusion of probable age of eocene and the sub volcanic domes of miocene age plausible mineralized zones in this high potential area can be delimited based on mineral prospectivity maps during the regional exploration surveys however the success of mineral prospectivity mapping mpm is always plagued by different types of uncertainties stochastic and systemic the main aim of this study is to reduce those uncertainties resulting from a the imprecise incorrect selection of targeting criteria b adverse effects of using inefficient or least efficient evidence maps and c employing an integration methodology which suffers from user interference in this regard the first case was modulated through the precise identification and selection of controls on mineralization as well as ore forming processes the second case was declined by the sensitivity analysis of input geochemical geological and structural parameters to mpm using the area under the receiver operating characteristics roc curve and the third case was controlled by incorporation of genetic algorithm ga and artificial neural networks here mlp ann as a suitable data driven mpm method through sensitivity analysis and using mlp ga ann and mlp ann algorithms various prospectivity models were generated and compared the results of prediction rate curves demonstrated that the exclusion of poor evidence maps and that employing a self adapted data driven approach e g mlp ga ann can significantly reduce the systematic uncertainty in mapping of mineral prospectivity accordingly the superior model was then selected for delineating efficient exploration targets

trampoline effect in extreme ground motion in earthquake hazard assessment studies the focus is usually on horizontal ground motion however records from the 14 june 2008 iwate miyagi earthquake in japan a crustal event with a moment magnitude of 6 9 revealed an unprecedented vertical surface acceleration of nearly four times gravity more than twice its horizontal counterpart the vertical acceleration was distinctly asymmetric the waveform envelope was about 1 6 times as large in the upward direction as in the downward direction which is not explained by existing models of the soil response we present a simple model of a mass bouncing on a trampoline to account for this asymmetry and the large vertical amplitude the finding of a hitherto unknown mode of strong ground motion may prompt major progress in near source shaking assessments

progress in integrated quantitative mineral resource assessments abstract three part resource assessments begun over 30 years ago provide a framework for making decisions concerning mineral resources under conditions of uncertainty the parts include general locations of undiscovered deposits that are delineated from a deposit type s geologic setting frequency distributions of tonnages and grades of well explored deposits that serve as models of grades and tonnages of undiscovered deposits and number of undiscovered deposits that are estimated probabilistically by type recently improved deposit density models show how to make probabilistic estimates of numbers of undiscovered deposits significant progress has been made showing how to reduce uncertainty and risk by the practical integration of the fundamental kinds of information needed by decision makers the approach is founded on internally consistent mineral deposit models that help convert the output of assessments into forms helpful to decision makers this integration of models and methods is a source of strength that reduces the chances of biased estimates but it is also a burden requiring careful development of models and applications of methods before decisions are made on where to explore decisions must be made about what to explore for and whether it is worth the risk

dda validation of the mobility of earthquake induced landslides abstract this paper studies the run out of earthquake induced landslides there are more than 20 mechanical models to explain long run out of rapid landslides including some earthquake induced landslides however notably few of them considered the effect of seismic loading on the run out of landslides in a previous study we have proposed a model which is called the multiplex acceleration model mam to interpret the long run out mechanism and a shaking table test has been performed to verify the mam because the previous mam is a conceptual model and only a single stone has been examined under sine waves by the shaking table test the mam needs to be extended and further verified in this paper the mam was extended by introducing the movement change that was induced by the so called trampoline effect of earthquake loading and the latest practical numerical simulation program discontinuous deformation analysis dda was used to verify the mobility of earthquake induced landslides after a conceptual landslide model was used to verify the effect of seismic loading on the mobility the donghekou landslide which was a typical long run out landslide that was induced by the 2008 wenchuan earthquake was analyzed the results show that the seismic loading could be one of the factors that could eventually help increase the run out of landslides

rupture process of the 2008 iwate miyagi nairiku japan earthquake derived from near source strong motion records abstract we derive the rupture process of the 2008 iwate miyagi nairiku japan earthquake m jma 7 2 during which the largest ground acceleration to date namely 4022 cm sec 2 was recorded at a hanging wall station iwth25 station of kik net just above the hypocenter velocity waveform data 0 1 1 hz at 14 strong motion stations of k net and kik net including the borehole records of iwth25 are inverted using the multi time window linear waveform inversion method we assume a horizontally layered velocity structure model having low velocity subsurface layers for each station in order to calculate the green s functions the waveform inversion indicates that there are two major slip patches one patch extends from the hypocenter to the southern shallower part of the fault a particularly large slip area in this patch is centered approximately 8 km to the south of the hypocenter with a maximum slip of 6 2 m the area ruptured between 4 and 9 sec after the initial break the other patch with smaller slip is located in the northern part which broke after the rupture of the southern slip patch the initial 0 4 sec rupture occurred beneath iwth25 contributing to the synthesis of a distinctive upward velocity pulse at this station examination of the slip contribution to the synthetic velocity waveforms and comparison of the isochrones with the slip distribution suggest that a peak acceleration greater than 4000 cm sec 2 observed at iwth25 was generated from the area that is closest to the hypocenter in the southern particularly large slip area

response of high strength rock slope to seismic waves in a shaking table test studies on landslides by the 2008 wenchuan earthquake showed that the topography is of great importance in amplifying the seismic shaking the present study carried out experiments on rock slopes by means of a shaking table the recorded wenchuan earthquake waves are scaled to excite the model slopes measurements from accelerometers installed on free surface of the model slope simulating high strength rocks are analyzed with much effort on acceleration responses to both horizontal and vertical components of seismic shaking it is found that the amplification factor of peak horizontal acceleration pha is increasing with elevation of the model slope though the upper and lower halves of the slope exhibit different increasing patterns the amplification factor of peak vertical acceleration pva exhibits a lying s shaped changing trend with the elevation indicating attenuations of pvas at the toe and top of a slope in addition the xz direction shaking produces a horizontal and vertical response stronger than x direction and z direction shaking alone both pha and pva increase with the excitation intensity however the corresponding amplification factors generally decrease indicating the acceleration response of a slope weakens with the excitation intensity of shaking finally the statistic of ratio of pva to pha indicates that 85 of the slope height especially the upper middle part is likely subject to pvas greater than or equal to 2 3 of pha and 32 of the slope height to pvas greater than or equal to pha this indicates the nonignorable role of pva in responses of a slope to an earthquake and necessity of considering during design work

mapping singularities with stream sediment geochemical data for prediction of undiscovered mineral deposits in gejiu yunnan province china abstract this paper proposes the concept of singularity for characterizing hydrothermal mineralization processes a singular physical process may result in anomalous amounts of energy release or material accumulation within a narrow spatial temporal interval mineralization can be considered as a type of singular process due to large amounts of material accumulation and element enrichment a spatial singularity mapping technique is developed based on the local singularity involved in the context of multifractal theory it assembles geochemical map at different scales and calculates an index indicating the scaling characteristics of enrichment and depletion of geochemical concentration at multiple scales this index was used for quantifying spatial singularity of mineralization associated geochemical anomalies a case study for the gejiu tin polymetallic mineral district yunnan province china demonstrates that the concepts of singularity and the singularity mapping technique are applicable and useful for delineating anomalies caused by mineralization and for predicting the locations of undiscovered mineral deposits

the eclipse drill a field portable intermediate depth ice coring drill a derivative of the danish tipping tower intermediate depth ice coring drill system has been developed for use in remote areas the system as described is capable of drilling to depths of 250 m although the drill has been proven to 350 m the drill system is designed to be transported by hand and consumes 700 w maximum power from a 24 v d c battery bank charged by solar panels or a small generator a field test in the st elias mountains yukon produced good quality core to 161 6 m depth drilling at 6500 m a s l on far east rongbuk glacier mount everest produced good core to 42 m depth

mapping mineral prospectivity through big data analytics and a deep learning algorithm abstract identification of anomalies related to mineralization and integration of multi source geoscience data are essential for mapping mineral prospectivity in this study we applied big data analytics and a deep learning algorithm to process geoscience data to identify and integrate anomalies related to skarn type iron mineralization in the southwestern fujian metallogenic zone of china based on the geological setting and environment for the formation of skarn type iron mineralization 42 relevant variables including two geological one geophysical and 39 geochemical variables were analyzed and integrated for detecting anomalies related to mineralization using a deep autoencoder network the results indicate that the mapped prospectivity areas have a strong spatial relationship with the locations of known mineralization and demonstrate that big data analytics supported by deep learning methods is a potential technique to be considered for use in mineral prospectivity mapping

imaging the high frequency energy radiation process of a main shock and its early aftershock sequence the case of the 2008 iwate miyagi nairiku earthquake japan to understand the energy release process that operates at the end of the main shock rupture and start of the aftershock activity we propose an inversion method that uses continuous high frequency seismogram envelopes of the main shock and early aftershocks i e events that occur at short times after the main shock in our approach the aftershock sequence is regarded as a continuous energy release process rather than a discrete time series of events to correct for the contribution of coda wave energy excited by multiple scattering we use the theoretical envelope synthesized on the basis of the radiative transfer theory as a green s function the site amplification factors are corrected considering the conservation of energy flux and using the coda normalization method the inverted temporal energy release rate for the 2008 mw 6 9 iwate miyagi nairiku earthquake japan decays following t 1 1 at the lapse time t of 40 900 s after the main shock origin time this exponent of the decay rate is similar to the p value of the modified omori law the amount of estimated energy release is consistent with that calculated from the magnitude listed in the aftershock catalog although the uncertainty is large the location of large energy release at the lapse times of 40 900 s approximately overlaps to that of the aftershocks which surrounds the large energy release area during the main shock faulting the maxima of the energy release rate normalized by the average decay rate distributes following a power law similar to the gutenberg richter law

dynamic response of rock slopes to oblique incident sv waves abstract most dynamic response analyses of rock slopes only consider the vertical incidence of seismic waves however obliquely incident waves dominate in near field seismic areas this paper presents a new seismic input method that considers near field oblique incidence based on mechanisms of artificial viscous boundaries and the influence of incident angle on the dynamic response of rock slopes three numerical model slopes with different slope angles of 30 45 and 60 are excited with the el centro earthquake record assuming varying incident angles from 0 to 90 the results show that the incident angle significantly affects the dynamic response of the slopes the most damaging incident directions are approximately perpendicular to the slope surface rather than in the vertical direction the dynamic response of the slopes will be underestimated if only the vertical incidence is considered the incident angle affects the reflection wave field in the slope and the areas affected by the reflection waves decrease with increasing slope angle however the predominant period of the response spectrum of the rock slopes is not sensitive to the incident angle and location this study unveils the dynamic mechanism of earthquake induced rock slides which is of significance for earthquake hazard prevention

coseismic velocity change in and around the focal region of the 2008 iwate miyagi nairiku earthquake 1 the 2008 m7 2 iwate miyagi nairiku earthquake occurred in ne japan where dense seismic networks exist using the data from these networks we determined the coseismic seismic velocity change associated with this earthquake by two different methods ambient noise interferometry and vertical array interferometry of coda wave the purpose of this article is to reveal the spatial distribution and the cause of the velocity change by integrating these two approaches ambient noise interferometry revealed a coseismic velocity decrease of rayleigh wave by 0 1 0 5 at 0 25 0 5 hz we also estimated the spatial distribution of the velocity change by a tomographic inversion the velocity decrease was distributed in and around the focal area in the second method we applied cross correlation analysis to coda waves observed by the kik net vertical array we detected a shear velocity decrease of approximately 5 in shallow layers up to a few hundred meters depth quantitative comparison of the two results reveals that the 5 shear velocity decrease in shallow layers can explain the 0 1 0 5 decrease of rayleigh wave velocity the distribution of the velocity decrease is similar to that of the strong ground motion and the static stress change however a significant velocity increase is not observed in the compression area where a velocity increase is expected based on the observations we consider that the primary factor affecting the velocity change is damage in shallow layers due to strong motion the effect of the static stress change might be masked by the larger effect of the strong motion

how does the ground shake when earthquakes occur near man made structures such as buildings or dams not only the absolute magnitude but also the precise characteristics of ground motions of the main shock and the aftershock determine the damage that occurs unconsolidated materials such as soil amplify ground motions more than rocks do but at the high strains near major earthquakes the behavior of the soils may be modified by scattering or nonlinear effects frankel discusses recent insights gained by o9connell page 2045 that shed new light on these scattering effects and points out that closely spaced monitoring networks are imperative if we are to understand the time histories of earthquake ground motions

compositional data analysis in the study of integrated geochemical anomalies associated with mineralization abstract geochemical data are typical compositional data which should be opened prior to univariate and multivariate data analysis in this study a frequency based method robust principal component analysis rpca and a frequency space based method spectrum area fractal model s a are applied to explore the effects of the data closure problem and to study the integrated geochemical anomalies associated with polymetallic cu mineralization using a stream sediment geochemical dataset collected from the zhongteng district fujian province china the results show that 1 geochemical data should be opened prior to rpca to avoid spurious correlation between variables 2 geochemical pattern is a superimposition of multi processes and should be decomposed and 3 the s a fractal model is a powerful tool for decomposing the mixed geochemical pattern

statistical features of short period and long period near source ground motions abstract this study collects recorded ground motions from the near source region of large earthquakes and considers to what extent this historic record can inform expectations of future ground motions at similar sites the distribution of observed peak ground acceleration pga is well approximated by the lognormal distribution and we expect the observed distribution to remain unchanged with the addition of data from future earthquakes however the distribution of peak ground displacements pgd will likely change after a well recorded large earthquake specifically we expect future observations of pgd greater than those previously recorded we use seismic scaling relations to motivate the expected distribution of pgd as uniform on the logarithmic scale or at least fat tailed because pga does not scale with fault rupture area or slip on the fault there are no such scaling relations to predict the observed distribution of pga the observed records show that there is essentially no correlation between pgd and pga for near source ground motions from large events the large uncertainty in a future value of pgd in the near source region of a large earthquake exists despite the ability of earth scientists to accurately model long period ground motions in contrast the relative certainty in a future value of pga exists despite the inability to model short period ground motions reliably the stability of the observed distribution of pga with respect to new ground motion records enables us to predict the distribution of future pga and to calculate the probability of exceeding the largest recorded pga

changes in shear moduli of liquefied and nonliquefied soils during the 1995 kobe earthquake and its aftershocks at three vertical array sites acceleration records of the 1995 kobe earthquake and its first after shocks provided by vertical arrays at port island pi sgk and tks sites were used to estimate changes in the shear moduli of subsurface soils caused by strong ground motion shear moduli estimates are based on stress strain relations deter mined for consecutive time intervals during the mainshock and aftershocks we found that in the upper 0 13 m at pi reclaimed fill above the groundwater level the shear modulus decreased by 80 90 of its initial value owing to liquefaction signs of its recovery appeared 3 5 min after the decrease in the intensity of strong motion at depths of 13 18 m reclaimed fill below the water level and 27 32 5 m water saturated sand at pi 0 11 m at sgk and 0 14 m at tks water saturated alluvium the shear modulus decrease was estimated at about 80 50 60 60 70 and 50 respectively recovery began immediately after the decrease in the intensity of strong motion and was completed within a few minutes the results show that the behavior of the upper layers at sites pi and sgk where the highest accelerations were recorded was dynamically unstable so far as the method can be applied to any site where vertical array records and profiling data are available ac cumulation of representative data on nonlinear soil behavior during strong motion for various soil conditions is desirable summarizing and generalizing these data we may be able to predict soil behavior in future earthquakes

nonlinear behavior of soils revealed from the records of the 2000 tottori japan earthquake at stations of the digital strong motion network kik net acceleration records of the tottori earthquake 6 october 2000 pro vided by stations of the digital strong motion network kik net show clear evidence of the nonlinearity of soil response at sites located in near fault zones in this study records of the mainshock of the tottori earthquake are analyzed and stresses and strains induced by the strong motion in the upper 100 or 200 m of soil are recon structed at sites located within 80 km from the fault plane for reconstructing stresses and strains the method is applied which we developed and used previously for studying the response of soils during the 1995 kobe earthquake nonlinear time dependent stress strain relations in the soil layers are estimated based on vertical array records a good agreement between the observed and simulated accelerograms of the tottori earthquake testifies to the validity of the obtained vertical distributions of stresses and strains in the soil layers we also evaluated variations of the shear moduli of the soil layers caused by the strong motion at stations located at different distances from the fault plane changes in the rheological properties of the upper soil layers were found at the stations closest to the fault plane a similarity in stress strain relations describing the behavior of similar soils during the 1995 kobe earth quake and the 2000 tottori earthquake was obtained indicating the possibility of precasting soil behavior in future earthquakes at sites where profiling data are available

nonlinear soil behavior observed at vertical array in the kashiwazaki kariwa nuclear power plant during the 2007 niigata ken chuetsu oki earthquake abstract the kashiwazaki kariwa nuclear power plant suffered extreme shaking during the 2007 niigata ken chuetsu oki earthquake accelerograms observed at the dense seismometer array in the plant are now open to the public and will provide valuable knowledge the temporal changes of s wave velocity were examined by using normalized input output minimization niom method based on the vertical array records observed during the mainshock and the events before and after it it was found that the s wave velocity in the layers surface 50 m depth and 50 100 m depth decreased significantly during the principal motion of the mainshock indicating nonlinear behavior whereas nearly linear behavior was observed in the bedrock layer below 100 m depth it was also found that the s wave velocity increased in the layers above 100 m depth soon after this motion indicating no major liquefaction in these layers finally the relationship between the shear modulus and shear strain was examined based on the obtained s wave velocities the normalized shear moduli g g 0 in the surface and intermediate layers decreased to about 0 2 at a strain level of 1 10 3 to 1 10 2 and about 0 6 at a strain level of 1 10 3 to 2 10 3

the 2014 cephalonia earthquakes finite fault modeling fault segmentation shear and thrusting at the nw aegean arc greece we present refined finite fault models ffm for the 2014 cephalonia keffalinia kefalonia seismic sequence mw 6 0 at the nw edge of the aegean arc ionian sea the area represents the seismically most active part of europe and a continental promontory in which fault modeling is a challenge because of structural complexity and poor coverage by seismological gps and insar data inversion was based on gps data and a new algorithm permitting fusion of slip vectors of individual earthquakes and of their cumulative dislocation and accepting constraints and collocation type analysis of uncertainties computed ffm which correspond to an essentially strike slip fault and a blind shallow oblique slip thrust were assessed by sensitivity analysis and insar data and are consistent with the tectonic fabric of the area they can also explain the observed extreme peak ground accelerations the 2014 faults in combination with ffms of the 2003 and 2015 leucas lefkada lefkas earthquakes farther ne and of the 1983 m7 0 earthquake farther sw constrain a 100 km long immature strike slip fault zone along close to the cephalonia leucas coasts this fault pattern previously regarded as a poorly documented cephalonia transform fault consists of occasionally overlapping oblique slip segments with variable geometric and kinematic characteristics in a shear zone landwards of the plate interface as evidence from seismic profiles reveals this pattern may explain the enigmatic superimposition of shear and compression in the nw edge of the aegean arc

introduction to the special issue mineral prospectivity analysis and quantitative resource estimation abstract this introduction provides an overview of the history present status and future perspective of research in the fields of mineral prospectivity analysis and quantitative resource estimation it also summarizes the papers included in the special issue

exploration information systems a proposal for the future use of gis in mineral exploration targeting abstract the advent of modern data collection and storage technologies has brought about a huge increase in data volumes with both traditional and machine learning tools struggling to effectively handle manage and analyse the very large data quantities that are now available the mineral exploration industry is by no means immune to this big data issue exploration decision making has become much more complex in the wake of big data in particular with respect to questions about how to best manage and use the data to obtain information generate knowledge and gain insight one of the ways in which the mineral exploration industry works with big data is by using a geographic information system gis for example gis platforms are often used for integration interrogation and interpretation of diverse geoscience and mineral exploration data with the goal of refining and prioritising known and identifying new targets here we i briefly discuss the importance of carefully translating conceptual ore deposit models into effective exploration targeting maps ii propose and describe what we term exploration information systems eis a new idea for an information system designed to better integrate the conceptual mineral deposit model i e the critical and constituent processes of the targeted mineral system with data available to support exploration targeting and iii discuss how best to categorise mineral systems in an eis as scale dependent subsystems to form mineral deposits our vision for the future use of eis in exploration targeting is one whereby the mappable ingredients of a targeted mineral system are translated and combined into a set of weighted evidence or proxy maps automatically resulting in an auto generated mineral prospectivity map and a series of ranked exploration targets we do not envisage the eis replacing human input and ingenuity rather we envisage the eis as an additional tool in the exploration toolbox and as an intelligence amplifying system in which humans are making use of machines to achieve the best possible results

mesozoic tectonic evolution of the southeast china block new insights from basin analysis abstract in order to better understand the mesozoic tectonic evolution of southeast china block secb in short this paper describes geological features of mesozoic basins that are widely distributed in the secb the analyzed data are derived from a regional geological investigation on various mesozoic basins and a recently compiled 1 1 500 000 geological map of mesozoic cenozoic basins two types of basin are distinguished according to their tectonic settings namely the post orogenic basin type i and the intracontinental extensional basin type ii the latter includes the graben and the half graben or faulted depression basins our studies suggest that the formation of these basins connects with the evolution of geotectonics of the secb the post orogenic basin type i was formed in areas from the piedmont to the intraland during the interval from late triassic to early jurassic and the formation of the intracontinental extensional basin type ii connects with an intracontinental crustal thinning setting in the late mesozoic the graben basin was generated during the middle jurassic and is associated with a bimodal volcanic eruption and the half graben or faulted depression basin filled mainly by the rhyolite tuff and sedimentary rocks during early cretaceous is occupied by the late cretaceous paleogene red colored terrestrial clastic rocks we noticed that the modern outcrops of numerous granites and basins occur in a similar level and the mesozoic granitic bodies contact with the adjacent basins by large normal faults suggesting that the modern landforms between granites and basins were yielded by the late crustal movement the modern basin and range framework was settled down in the cretaceous abundant sedimentary structures are found in the various basins from that the deposited environments and paleo currents are concluded during the late triassic early jurassic time the source areas were situated to the north and northeast sides of the outcrop region in this paper we present the study results on one geological and geographical separating unit and two separating fault zones the wuyi orogenic belt is a late mesozoic paleo geographically separating unit the ganjiang fault zone behaves as the western boundary of early cretaceous volcanic rocks and the zhenghe dapu fault zone separates the se china coastal late mesozoic volcanic sedimentary basins and the wuyi orogenic belt finally we discuss the geodynamic mechanisms forming various basins proposing a three stage model of the mesozoic sedimentary evolution

evidential belief functions for data driven geologically constrained mapping of gold potential baguio district philippines abstract a data driven application of the theory of evidential belief to map mineral potential is demonstrated with a redefinition of procedures to estimate evidential belief functions the redefined estimates of evidential belief functions take into account not only the spatial relationship of an evidence with the target mineral deposit but also consider the relationships among the subsets of spatial evidences within a set of evidential data layer proximity of geological features to mineral deposits is translated into spatial evidence and evidential belief functions are estimated for the proposition that mineral deposits exist in a test area the integrated maps of degrees of belief for the proposition that mineral deposits exist in a test area is classified into a binary mineral potential map for the baguio district philippines the binary gold potential map delineates a about 74 of the training data i e locations of large scale gold deposits and b about 64 of the validation data i e locations of small scale gold deposits the results demonstrate the usefulness of a geologically constrained mineral potential mapping using data driven evidential belief functions to guide further surficial exploration work in the search for yet undiscovered gold deposits in the baguio district the results also indicate the usefulness of evidential belief functions for mapping uncertainties in the geologically constrained integrated predictive model of gold potential

deep seated downslope slip during strong seismic shaking 1 strong seismic waves cause frictional failure within regolith on hillslopes the material responds anelastically to the combined oscillating dynamic and static gravitational stresses gravity drives preferential downslope movement of the transiently weakened material the net effect over many earthquake cycles is a tens of meter thick slow landslide that is a sackung the classical approach to hillside failure involves downslope dynamic accelerations or equivalently downslope dynamic shear tractions rate and state friction quantifies that the starting coefficient of friction is a few tenths higher that the apparent long term coefficient of friction from the angle of repose 0 96 1 25 in the calculations retaining an extra digit furthermore the dynamic coulomb stress ratio for dynamic to lithostatic stress for s waves refracted toward vertical paths is the dynamic acceleration in g s above the scale depth 1 k the inverse of the wave number in more detail a dynamic acceleration of 0 13 0 35 g destabilizes slopes near the angle of repose seismologists expect such acceleration near active major faults compatible with the widespread occurrence of sackungen on steep slopes accelerations of 0 96 1 25 1 g destabilize shallow slopes leading to net downhill movement analogous to the movement of an object down a vibrating ramp however sackungen are rare or even absent on shallow slopes in california indicating the rarity of sustained 1 g accelerations a second mechanism may drive downhill movement on modest 19 slopes as observed in the san gabriel mountains of california near the san andreas fault the near field velocity pulse on strike slip faults produces only a few tenths g acceleration but particle velocities of over 1 m s 1 persisting over 1 s dynamic stresses and strains scale with this velocity and extend all the way to the free surface coulomb failure criteria are exceeded at shallow depths failure greatly weakens the regolith allowing it to move downhill in response to gravity this mechanism appears capable of producing prehistoric 1 m per event slip on modest slopes observed in the san gabriel mountains

earthquakes on dipping faults the effects of broken symmetry dynamic simulations of earthquakes on dipping faults show asymmetric near source ground motion caused by the asymmetric geometry of such faults the ground motion from a thrust or reverse fault is larger than that of a normal fault by a factor of 2 or more given identical initial stress magnitudes the motion of the hanging wall is larger than that of the footwall in both thrust reverse and normal earthquakes the asymmetry between normal and thrust reverse faults results from time dependent normal stress caused by the interaction of the earthquake generated stress field with earth s free surface the asymmetry between hanging wall and footwall results from the asymmetric mass and geometry on the two sides of the fault

strong seismic shaking of randomly prestressed brittle rocks rock damage and nonlinear attenuation strong seismic waves produce frequent episodes of transient oscillating dynamic stress in the shallow subsurface within seismically active areas dynamic stress drives slip on a network of preexisting small fracture planes and leaves residual stresses once shaking ceases the residual stresses act as prestresses during the next strong earthquake local failure occurs on fractures at low dynamic stresses where the prestresses are favorably aligned while most of the bulk rock remains intact hence nonlinear attenuation of strong seismic waves commences at dynamic stresses well below those for pervasive coulomb failure consideration of the fractal distribution of prestresses indicates that nonlinear attenuation increases rapidly with dynamic stress vertically propagating shear waves provide simple scaling relationships for quick application 1 nonlinear attenuation is concentrated near the quarter wavelength depth 2 the coulomb stress ratio dynamic lithostatic stress above the quarter wavelength depth scales with the sustained dynamic acceleration in g s rate and state friction thus provides estimates of the maximum sustained acceleration from coulomb stress ratio at failure 1 for regolith that has repeatedly failed 1 5 for shallow intact sandstone and 2 for shallow intact granite a potentially observable effect occurs with shallow brittle regolith on hillslopes where gravity causes net downslope creep during strong shaking analogous crack network behavior with prestress occurs in the damage zone surrounding the rupture zone of major faults pulverized rock forms at shallow depths when rock is repeatedly deformed in strong shaking to just beyond the elastic limit but strain does not localize into a crack network

applying modified discontinuous deformation analysis to assess the dynamic response of sites containing discontinuities abstract the accurate consideration of seismic wave propagation through discontinuous media is crucial in rock engineering discontinuous deformation analysis dda with the ability to study discontinuity behaviors is modified by incorporating a seismic input method based on a viscous boundary and the free field theory after confirming the accuracy of the modified dda using several verification examples two practical applications 1 the extreme ground motion during the 2008 iwate miyagi earthquake japan and 2 the donghekou landslide induced by the 2008 wenchuan earthquake china are simulated and reproduced by the modified dda the results show that seismic wave propagation through discontinuous media can be accurately simulated by the modified dda further the simulation results indicate that discontinuities are critical in the dynamic response of structures conclusively the modified dda provides an alternative approach for analyzing the dynamic response of sites containing discontinuities

exceptional ground motions recorded during the 26 april 2008 mw 5 0 earthquake in mogul nevada abstract an unusually shallow swarm of earthquakes in mogul a suburb in west reno nevada started 28 february 2008 and continued for several months temporary instruments in the epicentral region constrained event depths and locations and provided onscale recordings of the strong ground motions and supplemented a network of over 21 permanent advanced national seismic system anss strong motion stations deployed throughout the metropolitan reno area by the end of august the swarm had produced over 200 earthquakes with magnitude m l greater than 2 0 the largest earthquake in the sequence occurred at 06 40 utc on 26 april 2008 11 40 p m on 25 april local time with magnitude m l 4 7 m w 5 0 and a hypocentral depth of about 3 1 km in the m w 5 0 mainshock mean horizontal peak ground acceleration exceeded 0 6 g at three stations the strongest peak vector acceleration was 1164 cm sec 2 or about 1 19 g at the station mogl 0 4 km from the epicenter at a frequency of about 3 hz the mean horizontal peak velocity exceeded 12 cm sec at the four nearest stations and the peak vector velocity at the strongest was 54 cm sec the duration of the strongest shaking was about 2 sec at these stations the observed peak accelerations and peak velocities decreased more rapidly with distance than predicted to values below the median predictions at most stations in the reno metropolitan area the shallow source depth is to some degree a likely contributing factor to these unusual observations the motions in the residential neighborhood near the epicenter are significantly greater than the seismic forces required by the 1985 uniform building code zone 3 that was in effect when the mogul neighborhood was developed but damage to the wood frame structures in the neighborhood was minimal

linking mineral deposit models to quantitative risk analysis and decision making in exploration this paper describes a methodology of translating mineral deposit models into flexible probabilistic structures based on 1 extraction of ore components fluids metals and ligands from crustal or mantle sources or both 2 fluid or melt assisted transport of ore components from source to trap zones 3 formation of trap zones i e effective melt or fluid channels that can focus melt or fluid migration and accommodate large amounts of metal and 4 operation of the physicochemical processes that promote and sustain the deposition of metal from fluids or melts passing through a particular trap site our approach integrates these critical mineralization processes and conditions with concepts of probability theory decision analysis and financial modeling the principal objective is to make mineral deposit models amenable to financial risk and value analysis and suitable for communication of value creating geologic concepts to financial stakeholders in economic terms a case study based on an actual porphyry copper project illustrates how the resulting probabilistic mineral systems model can generate a measure of the probability of ore occurrence as an input for exploration decision trees and simulations to calculate the expected value of an exploration project and the probability distribution of all possible surrounding net present values npvs within a minimum and maximum range formulation of the probabilistic model closely follows and combines principles of the well established petroleum and mineral systems approaches and makes use of excel based model templates with decision tree and simulation add in software packages

prospectivity mapping for high sulfidation epithermal porphyry deposits using an integrated compositional and topographic remote sensing dataset abstract the targeting and discovery of epithermal porphyry mineral deposits can be enhanced using a structured quantitative methodology to analyse the distribution of ore deposits and model their spatial association with exploration evidence providing improved understanding on the controls of ore deposition a novel exploration tool integrating field and aster swir and tir satellite imagery has been developed which provides an enhanced means of resolving surface expressions of the residual silica core of the lithocap the alteration zones were clearly resolved by the remote sensing data and an intimate spatial relationship between high grade altered rocks and topographic highs was identified at a number of locations a mineral prospectivity modelling mpm approach parameterized by the results of the remote sensing study using a gis based weighted linear combination implementation of a multi criteria evaluation approach and utilising a fuzzy analytical hierarchy process to elucidate expert knowledge has been implemented to target high sulfidation epithermal porphyry deposits on the island of lesvos greece the results from this integrated altitudinal compositional modelling approach closely matched the hydrothermal alteration mapped in the field supporting the accuracy of this mpm approach

earthquake induced snow avalanches ii experimental study we conducted experiments on the stability of snow subjecting snow to vibrations with the aim of improving our understanding of poorly studied mechanisms behind the triggering of avalanches during earthquakes most experiments were carried out on a specially constructed shaking table using artificial snowpacks containing a weak layer accelerations in the snow samples were measured using high frequency sensors enabling calculation of vibration induced stresses within the snow at the moment of fracture we used a high speed camera to film different types of fracturing in all cases the vibrations caused failure of the snow by fracturing along the weak layer or at the base of the snow sample an additional inertial stress induced by accelerations normal to the shear plane was quantified we find that this stress can be related to smaller values of the shear strength in snow

evaluation of uncertainty in mineral prospectivity mapping due to missing evidence a case study with skarn type fe deposits in southwestern fujian province china in this paper the southwestern fujian metallogenic belt one of the important fe polymetallic belts in southern china was chosen as a case study area to evaluate the uncertainty due to missing evidence in mineral prospectivity mapping four geological features were considered important for mineral prospectivity mapping based on the geological model for skarn deposits in the belt 1 the yanshanian granitic intrusions because they provided energy fluids and part of the metal budget 2 faults because they served as pathways for hydrothermal fluids 3 the carboniferous permian carbonate sequences because they supplied part of the metal budget and served as host rocks for ore deposition and 4 geochemical anomalies because they indicate presence of skarn type alteration and mineralization four separate predictive evidence layers depicting each the above geological features were extracted from relevant geoscience data and were integrated using a modified fuzzy weights of evidence model which retains the advantages of both fuzzy weights of evidence and logistic regression modeling the results show that most of the known fe deposits occur in or near and thus have strong correlation with areas of high posterior probabilities as indicated by the delineated prospective areas that occupy only 4 6 of the studied region but contain 88 5 of the total number of known fe deposits different combinations of predictive evidence layers were used to examine prediction uncertainty related to missing evidence plots of accumulative number of fe deposits versus accumulative prospective areas show that the order of the most to the least important evidence of mineral prospectivity in the studied region is favorable rock types geochemical anomalies intrusive rocks faults results of blind testing the prospectivity models indicate that the geological model of fe mineralization in the belt is suitable for predicting exploration target areas for skarn type fe deposits and suggest that the highest risk in follow up exploration is related to sequences of carbonates in the carboniferous permian formations that were likely either not mapped or not represented at the present regional scale of mapping

a comparison study of the c a and s a models with singularity analysis to identify geochemical anomalies in covered areas abstract fractal multifractal modeling of geochemical data is an interesting topic in the field of applied geochemistry identification of weak anomalies for mineral exploration in covered areas is one of the most challenging tasks for utilization of geochemical data in this study three fractal models consisting of the concentration area c a spectrum area s a and singularity index models were applied to identify geochemical anomalies in the covered area located in the chaobuleng fe polymetallic district inner mongolia china the results show that 1 the grassland cover weakens the concentrations of geochemical elements 2 the c a model has a limitation to identify weak anomalies in covered areas 3 the s a model is a powerful tool to decompose mixed geochemical patterns into a geochemical anomaly map and a varied geochemical background map but suffers edge effects in an irregular shaped study area and 4 the singularity index is a useful tool to identify weak geochemical anomalies

coseismic and postseismic elastic wave velocity variations caused by the 2008 iwate miyagi nairiku earthquake japan 1 we analyze coseismic and postseismic velocity variations caused by the june 13 2008 iwate miyagi nairiku earthquake mw 6 9 using passive image interferometry pii seismic noise is correlated in order to reconstruct the green s function between two sensors shear wave velocity changes are determined by relating the coda parts of the daily green s functions to a long term reference green s function our study extends from january 2008 to august 2010 and includes the correlations for 190 station pairs in three different frequency ranges from 0 125 to 1 0 hz we show that combining the 9 different component cross correlation functions stabilizes the velocity change estimation and increases analysis resolution the observed velocity change curves can be fitted by model time series consisting of a coseismic velocity drop followed by logarithmic postseismic recovery and seasonal velocity variations the coseismic velocity drops are stronger at higher frequencies and are concentrated in the southern part of the fault zone a tomography algorithm was developed to reproject the observed velocity variations of the different sensor pairs onto the single sensors the depth distribution of coseismic changes was modeled for the three stations with the largest velocity drops at two stations the coseismic velocity changes are located in the upper several hundred meters the third station shows indications for deeper changes in the order of kilometers postseismic recovery takes significantly longer than the analyzed two year period seasonal velocity variations with periods of one year are observed at all analyzed frequencies for most station pairs

a stochastic approach for evaluating the nonlinear dynamics of vertical motion recorded at the iwth25 site for the 2008 mw 6 9 iwate miyagi inland earthquake the vertical accelerogram recorded at the iwth25 site located just above the earthquake fault of the 2008 m w 6 9 iwate miyagi inland earthquake showed nonlinear dynamics because of intrawave frequency modulation with a maximum amplitude close to 4 g due to the nonlinear response of the near surface layer at the site in the present paper a stochastic second order model is proposed to explain these observations the dynamics of the model are determined by the configuration of three pairs of complex conjugated poles in the z transform domain and the dynamics of these poles are interpreted in terms of the instantaneous frequency of the recorded acceleration signal the results of simulations using the proposed model show overall agreement with the recorded accelerogram including its maximum amplitude and its time of appearance the physical mechanism producing the displacement waveform is found to be analogous to a ball bouncing on a vibrating surface from the simulated and recorded seismograms it was apparent that at least two consecutive high bounces are required to produce extremely high accelerations of close to 4 g

seismically damaged regolith as self organized fragile geological feature 1 the s wave velocity in the shallow subsurface within seismically active regions self organizes so that typical strong dynamic shear stresses marginally exceed the coulomb elastic limit the dynamic velocity from major strike slip faults yields simple dimensional relations the near field velocity pulse is essentially a love wave the dynamic shear strain is the ratio of the measured particle velocity over the deep s wave velocity the shallow dynamic shear stress is this quantity times the local shear modulus the dynamic shear traction on fault parallel vertical planes is finite at the free surface coulomb failure occurs on favorably oriented fractures and internally in intact rock i obtain the equilibrium shear modulus by starting a sequence of earthquakes with intact stiff rock extending all the way to the surface the imposed dynamic shear strain in stiff rock causes coulomb failure at shallow depths and leaves cracks in it wake cracked rock is more compliant than the original intact rock cracked rock is also weaker in friction but shear modulus changes have a larger effect each subsequent event causes additional shallow cracking until the rock becomes compliant enough that it just reaches coulomb failure over a shallow depth range of tens to hundreds of meters further events maintain the material at the shear modulus as a function where it just fails the formalism provided in the paper yields reasonable representation of the s wave velocity in exhumed sediments near cajon pass and the san fernando valley of california a general conclusion is that shallow rocks in seismically active areas just become nonlinear during typical shaking this process causes transient changes in s wave velocity but not strong nonlinear attenuation of seismic waves wave amplitudes significantly larger than typical ones would strongly attenuate and strongly damage the rock

spatial analyses of exploration evidence data to model skarn type copper prospectivity in the varzaghan district nw iran abstract recognition of significant ore forming processes which control mineralization improves the efficiency of mineral prospectivity modeling in this study controlling processes of skarn copper mineralization in varzaghan district northwestern iran were distinguished by a series of spatial and numerical analyses comprising point pattern fractal fry and distance distribution methods the recognized processes were then translated to a set of exploration criteria of the deposits in the area based on the accomplished exploration criteria two data driven models of skarn copper prospectivity were generated using logistic regression and random forest techniques the comparison of two generated models demonstrated that the targets derived by the latter technique were more reliable for further exploration than those created by the former one

prospectivity analysis of orogenic gold deposits in saqez sardasht goldfield zagros orogen iran abstract diverse deposit types or mineral systems form by diverse geological processes so translation of knowledge about the controls of mineralization acquired from the 4d geological modeling into 2d spatial predictor maps is a major challenge for prospectivity analysis in this regard mathematical functions have been used to model the conceptual or perceived spatial relationships between geological variables and targeted type or system of mineralization in this paper due to the different models of spatial relationships between predictors and mineral deposits we investigated the performance of different fuzzification functions to quantify the relationships we demonstrated that various types of relationships between exploration features and a mineralization type sought could be quantified using different fuzzification functions for prospectivity analysis we illustrated the process of the prospectivity analysis by using a data set of orogenic gold deposits in saqez sardasht goldfield iran prospectivity modeling of orogenic gold mineralization in the study area showed that the ne sw trending targets have priority for further prospecting of the deposits

nonlinear behavior of strong surface waves trapped in sedimentary basins abstract numerical calculations and observations indicate that surface waves reverberate within sedimentary basins a site response approach is inapplicable to the nonlinear attenuation of these waves as the energy passes repeatedly through the shallow subsurface computed dynamic stresses obtained by using published shakeout calculations graves et al 2008 indicate that nonlinear attenuation is modest but not negligible in the los angeles california basin for large earthquakes on the san andreas fault the dominant surface waves have velocity amplitudes of 1 5 m sec 1 and periods 3 5 sec around 20 of the total elastic strain energy resides above dynamic lithostatic stress ratios of 0 2 for both rayleigh and love waves where prestressed rock is highly likely to fail somewhat in friction

numerical analysis of near field asymmetric vertical motion abstract during the 2008 iwate miyagi nairiku japan earthquake m w 6 9 an unprecedented vertical surface acceleration of nearly four times gravity was measured at the kik net iwth25 station located 3 km southwest of the epicenter the station is equipped with three component accelerometers installed at both the free surface and the bottom of a 260 m borehole the waveform of the vertical acceleration shows a clearly asymmetric form with large amplitude in the upward direction aoi et al 2008 reported and qualitatively explained the mechanism of this phenomenon by the analogy of bouncing a piece of matter on a trampoline thus they called it the trampoline effect to study this recently discovered nonlinear behavior of the surface ground motion numerical analysis with a two dimensional finite element method has been conducted with parameters derived from the borehole data at the station the analysis successfully simulates the asymmetric vertical motion results indicate that the asymmetric motion may be characterized by the existence of a lower bound of negative acceleration which in most cases corresponds to the acceleration of gravity and high positive pulses caused by the compression stress of the disturbed surface ground material