reservoir fluid substitution effects on seismic profile interpretation a physical modeling experiment p wave seismic surveys are performed on realistic physical models of a reservoir formed of interbedded sand and shale layers and filled with gas water and oil they show characteristic behaviour which can be used to distinguish between fluids with significant implications for the interpretation of time lapse experiments discontinuous reflections originate in gas filled reservoirs with widely varying amplitude compared to oil or water filled reservoirs anomalous changes in seismic amplitude difference attributes for reflections within the reservoir are seen for gas oil substitution oil water substitution results in only weak variations of reservoir elastic properties thus amplitude difference attributes may be unsuitable for monitoring changes in oil water saturation however direct differences between the time traces are strong on time lapse sections strong amplitude difference anomalies do not necessarily correspond to the region where the fluid variations occur this is significant for monitoring oil field development by water injection

density porosity and magnetic susceptibility of carbonaceous chondrites abstract we report physical properties bulk and grain density magnetic susceptibility and porosity measured using nondestructive and noncontaminating methods for 195 stones from 63 carbonaceous chondrites grain densities over the whole population average 3 44 g cm 3 ranging from 2 42 g cm 3 ci1 orgueil to 5 66 g cm 3 cb bencubbin magnetic susceptibilities in log units of 10 9 m3 kg 1 averaged log 4 22 ranging from 3 23 cv3 axtell to 5 79 cb bencubbin porosities averaged 17 ranging from 0 for a number of meteorites to 41 for one stone of the co ornans notably we found significant differences in porosity between the oxidized and reduced cv subgroups with the porosities of cvo averaging approximately 20 and cvr porosities approximately 4 overall porosities of carbonaceous chondrite falls trend with petrographic type from type 1 ci near 35 type 2 cm cr averaging 23 type 3 cv co 21 to type 4 ck and some co averaging 15 there is also a significant decrease in porosity between meteorites of shock stage s1 and those of s2 indicative of shock compression

3 d seismic horizon based approaches to fracture swarm sweet spot definition in tight gas reservoirs in this article we will discuss some horizon attribute based methods that we have been exploring to help identify productive fracture swarms in tight gas reservoirs

evolution of atchafalaya lacustrine deltas south central louisiana abstract the entrenched pleistocene holocene mississippi alluvial valley was cut during the last low sea level stand and alluviation of the entrenched valley occurred during the holocene sea level rise regional gulf coast structures salt domes and faults have strongly influenced the morphology of the valley valley paleotopography has controlled depositional patterns and locations of major river courses as well as partially isolated large interdistributary basins within the alluvial deltaic plain interdistributary basin formation is further enhanced by distributary channel progradation switching and abandonment in conjunction with compactional subsidence of the alluvial plain surface geomorphology and sediment cores from the atchafalaya basin louisiana revealed that this basin has alternately accumulated fine grained organic rich sediments and terrigenous clastic dominated meander belt and lacustrine deposits basin subsidence and the presence of an active distributary channel in the basin are major determinants of the lithology of the sedimentary fill prograding lacustrine deltas of the atchafalaya river are the primary mechanism for filling the atchafalaya basin these upward coarsening deltas are relatively thin 3 m but are areally extensive tens to hundreds of kilometers and because they occur so frequently during the infilling process they account for a significant volume of the basin sequence the atchafalaya basin sequence documents lacustrine deltaic episodes dating from the early holocene maringouin and teche deltas to the present atchafalaya delta continued development of the atchafalaya river will rework portions of the backswamp and lacustrine deposits into meander belt deposits upon complete filling of the atchafalaya basin sediment will mostly bypass the basin and become deposited in the marine delta in atchafalaya bay

3d simulations of multi segment thrust fault rupture thrust faults such as those that underlie the los angeles basin are typically segmented by tear faults that offset the thrust fault segments we perform 3d finite difference simulations of earthquake rupture to evaluate the effectiveness of these offsets in retarding rupture the simulations include orthogonal intersecting faults to model the interaction of the thrust fault segments with the tear fault for reasonable assumptions for fault segment length strength and stress drop rupture can jump offsets of up to 2 km if a tear fault is present consistent with observations of well studied thrust earthquakes absent a tear fault the maximum offset that can be breached is an order of magnitude smaller

dynamics of dip slip faulting explorations in two dimensions dynamic models of earthquake rupture and slip are a powerful method by which to investigate the physics of earthquakes owing to both conceptual and computational constraints dynamic earthquake models have largely been limited to cases with geometrical symmetry such as faults in unbounded media or vertical faults however there are both observational and theoretical reasons to believe that nonvertical dip slip faults behave differently from faults with more symmetrical geometries previous observations have shown greater ground motion from thrust reverse faults than normal faults and higher ground motion on hanging walls than on footwalls in the present work two dimensional dynamic simulations of thrust reverse and normal earthquakes show precisely these effects and also elucidate their causes for typical nonvertical dip slip faults the breakdown of symmetry with respect to the free surface allows radiated seismic waves to reflect off the free surface and to hit the fault again altering the stress field on the fault this process can lead to time dependent normal stress and a feedback between the friction rupture processes and seismic radiation this interaction leads to thrust reverse faults producing much higher fault and ground motion than normal faults with the same geometry and stress magnitudes the asymmetric geometry also directly leads to higher motion on the hanging walls of such faults than on the footwalls simulations show that these effects occur for a variety of dip angles but only for faults that either intersect or closely approach the free surface the results emphasize the strong effect that the free surface can have on the dynamics of fault rupture and slip

a meteorite from the cretaceous tertiary boundary cretaceous tertiary boundary sediments are now widely recognized to contain the record of a large asteroid or comet impact event1 probably at the site of the chicxulub crater on the yucatan peninsula2 after nearly two decades of intensive research however much remains unknown about the specific nature of the projectile and of the impact event itself here we describe a 2 5 mm fossil meteorite found in sediments retrieved from the cretaceous tertiary boundary in the north pacific ocean that we infer may be a piece of the projectile responsible for the chicxulub crater geochemical and petrographic analyses of this meteorite indicate that it probably came from a typical metal and sulphide rich carbonaceous chondrite rather than the porous aggregate type of interplanetary dust considered typical of cometary materials3 the fact that meteorite survival should be enhanced by impacts at low asteroidal velocities4 also implies that this meteorite had an asteroidal rather than a cometary origin

dynamic rupture processes on a dipping fault and estimates of stress drop and strength excess from the results of waveform inversion summary the dynamic rupture processes on a dipping fault in a horizontally layered medium are investigated on 3 d spontaneous shear crack models the wave equations for the 3 d space are solved numerically by a finite difference method under appropriate boundary conditions the displacement components right above and right below the dipping fault plane have been obtained by solving the boundary conditions across the fault it was found that the final fault slip on the hanging wall side is appreciably larger than that on the foot wall side and that their amount is quite sensitive to the fault depth and the elastic heterogeneities of the medium particularly of the existence of low velocity surface layers on the basis of the above model the dynamic rupture process of the 1961 kita mino earthquake in central japan has been investigated with constraints of the fault parameters derived from the results of waveform inversion analysis for this purpose a locking fracture criterion was introduced for rupture propagation from which a lower bound of the maximum shear stress before the rupture and hence of the strength excess has been estimated the dynamic stress drop has also been evaluated by repeated iterations to minimize the difference between the dynamic and kinematic fault slips the results revealed quite heterogeneous distribution of strength excess indicating large values near the sw section of the fault at shallow depths and in the central bottom section in contrast to small values at mid depths in the ne section around the rupture nucleus zone the distribution of stress drop was also found to be heterogeneous with the existence of high stress drop zones in the ne shallow and bottom sections and a low stress drop zone at most of mid depths except in the sw section these results suggest that the dynamic rupture of this earthquake initiates at a small nucleus zone with low strength excess and small stress drop then broke the shallower and deeper fault sections with moderate strength excess and high stress drop and finally ruptured barrier zones with high strength excess these zones may be interpreted as weak and strong asperities and barriers respectively

the effects of fault orientation and fluid infiltration on fault rock assemblages at seismogenic depths abstract the factors controlling the development of different types of fault rock assemblages and more specifically the formation of friction melts are still not fully understood in this study we compared two exhumed strike slip faults in the adamello batholith southern alps the gole larghe and the passo cercen fault zones active at 9 11 km depth and temperatures of 250 300 c each fault zone consists of hundreds of sub parallel strands exploiting pre existing joints the gole larghe fault strikes n105 5 and is dextral the fault rocks are cataclasites and widespread centimetre thick pseudotachylytes the passo cercen fault strikes on average n130 and is formed by multiple fault horizons fault segments striking n105 n130 are mainly dextral whereas faults striking n135 n140 are mainly sinistral microstructural mineralogical and geochemical investigations show that the fault rocks are cataclasites associated with thick epidote k feldspar quartz veins and rare millimetre thick pseudotachylytes field evidence suggests that in both fault zones the direction of the maximum horizontal stress 1 was n135 the gole larghe fault strikes at about 30 to 1 and is favourably oriented for reactivation by contrast the passo cercen fault strikes at low angles to 1 and is unfavourably oriented for reactivation therefore requiring the development of high pore pressures as suggested by the occurrence of extensive epidote veining and hydraulic breccias it is proposed that frictional melting in the passo cercen fault zone was inhibited by the development of high pore pressures and low effective normal stresses

artificial neural network ensembles applied to the mapping of landslide susceptibility abstract this study proposes a comprehensive methodology to the application of an artificial neural network ensemble anne for the mapping of landslide susceptibility the identification of susceptible areas was performed on the basis of landslide inventory databases and seven parameters from three classes geomorphological elevation aspect slope topographic moisture index profile curvature geological lithology and environmental land use studies are presented for two major cities in brazil porto alegre and rio de janeiro as the main result we show that the susceptibility maps generated by the anne feature higher accuracy than those published by official organs such as the brazilian geological survey and geotechnical institute foundation geo rio this indicates that the proposed methodology can be an effective tool to assist the development of reliable landslide susceptibility maps in an efficient and agile manner

analytic network process model for landslide hazard zonation various controlling factors such as lithology slope angle slope aspect landuse channel proximity etc are generally considered for the landslide hazard assessment although outer dependence of these parameters to a landslide is inevitably taken into account inter dependence among the factors is seldom addressed analytic network process anp is the multi criteria decision making mcdm tool which takes into account such a complex relationship among parameters in this research an anp model for landslide susceptibility is proposed priority weights for each parameter controlling the landslide were determined and a hazard map was prepared of an area in a fragile mountainous terrain in the eastern part of nepal the data used in the example were derived from published sources aerial photographs and a topographic map however the procedures developed can readily incorporate additional information from more detailed investigations

possible fault plane in a seismic gap area of the southern apennines italy revealed by receiver function analysis 1 unusual features in teleseismic receiver function computed at a single three component seismic station reveal the presence of a dipping interface in the shallow crust with a pronounced seismic velocity contrast in the campania lucania region southern apennines italy the locus of this finding is the pergola melandro basin situated between the maximum intensity areas of two of the most destructive earthquakes reported in the italian seismic catalogue the m 7 0 val d agri earthquake 1857 and the ms 6 9 irpinia earthquake 1980 this area is not associated with known historical events and for this reason is currently object of investigation as a potential seismic gap where the probability of future ruptures is higher than in surrounding regions also for the static stress increase caused by the two above mentioned earthquakes through an inversion procedure applied to the computed receiver functions we are able to satisfactorily constrain the strike dip depth and velocity contrast of this crustal discontinuity whose geometric characteristics closely match those proposed by some authors for the sources of the two neighboring earthquakes we argue that the detected interface is the seismogenic source which fills the gap the findings of this study could open new perspectives both in the study of seismic gap areas and in the identification of historical earthquake sources offering a new and effective tool to locate investigate and constrain buried or unknown faults

slope stability evaluation using back propagation neural networks the yudonghe landslide located in western hubei province of china consists of eastern and western subunits as well as a main landslide mass with upper and lower slip surfaces as an important landslide close to shuibuya dam on the qing river its stability is crucial as the slide might reactivate because of a change in ground water level caused by filling of the shuibuya reservoir existing weakness zones growth of ruptures the downslope attitude of geologic strata and water infiltration which reduced the strength of rocks and soils have been found to be the most important factors contributing to the yudonghe landslide with regard to the landslide processes it can be noted that the original large scale slide activity was due to erosion by the qing river the second sliding resulted from the fall of blocks from the head scarp and the final activity was the growth of the eastern and western secondary slides a base failure was the main type of slope movement however it was obvious that more than one sliding event occurred as inferred from striations and fractures detected by microstructure analysis of soils along the failure surfaces slope instability was evaluated by the method of back propagation neural networks bpnn in which a four layer bpnn model with five input nodes two hidden layers and two output nodes was constructed using a training data set of landslide samples throughout the qing river area the predicted results of this analysis showed that the factor of safety was 1 10 which indicates that the yudonghe landslide is currently in a marginally stable condition

rupture processes of the 2004 chuetsu mid niigata prefecture earthquake japan a series of events in a complex fault system 1 we relocated the hypocenters of the 2004 chuetsu earthquake sequence niigata japan using the double difference method the distribution of aftershocks reveals a complex fault system consisting of five different fault planes inversions of strong motion records for the five major events within the sequence indicate that the mainshock mw 6 6 and the largest aftershock mw 6 3 occurred on parallel wnw dipping fault planes the zones of large slip asperities of these two events are located near the hypocenters in contrast the three other large earthquakes mw 5 9 5 7 and 5 9 occurred on east dipping fault planes oriented perpendicular to the fault plane of the mainshock we used slip distributions deduced from waveform inversions to estimate the coulomb failure stress changes that occurred immediately prior to each event cff values were positive at the hypocenters and within the asperities of the major aftershocks these results suggest that stress changes resulting from individual earthquakes led directly to the occurrence of subsequent earthquakes within the complex fault system

neural network based model for assessing failure potential of highway slopes in the alishan taiwan area pre and post earthquake investigation abstract this paper is aimed at creating an empirical model for assessing failure potential of highway slopes with a special attention to the failure characteristics of the highway slopes in the alishan taiwan area prior to and post the 1999 chi chi taiwan earthquake the basis of the study is a large database of 955 slope records from four highways in the alishan area artificial neural network ann is utilized to learn from this database the developed ann model is then used to study the effect of the chi chi earthquake on the slope failure characteristics in the alishan area significant changes in the degrees of influence of several factors variables are found and possible reasons for such changes are discussed the novelty of this paper lies in the fact that the developed ann models are used as a tool to investigate the slope failure characteristics before and after the chi chi earthquake

3 d seismic attributes using a semblance based coherency algorithm seismic coherency is a measure of lateral changes in the seismic response caused by variation in structure stratigraphy lithology porosity and the presence of hydrocarbons unlike shaded relief maps that allow 3 d visualization of faults and channels from horizon picks seismic coherency operates on the seismic data itself and is therefore unencumbered by interpreter or automatic picker biases we present a more robust multitrace semblance based coherency algorithm that allows us to analyze data of lesser quality than our original three trace cross correlation based algorithm this second generation semblance based coherency algorithm provides improved vertical resolution over our original zero mean crosscorrelation algorithm resulting in reduced mixing of overlying or underlying stratigraphic features in general we analyze stratigraphic features using as narrow a temporal analysis window as possible typically determined by the highest usable frequency in the input seismic data in the limit one may confidently apply our new semblance based algorithm to a one sample thick seismic volume extracted along a conventionally picked stratigraphic horizon corresponding to a peak or trough whose amplitudes lie sufficiently above the ambient seismic noise in contrast near vertical structural features such as faults are better enhanced when using a longer temporal analysis window corresponding to the lowest usable frequency in the input data the calculation of reflector dip azimuth throughout the data volume allows us to generalize the calculation of conventional complex trace attributes including envelope phase frequency and bandwidth to the calculation of complex reflector attributes generated by slant stacking the input data along the reflector dip within the coherency analysis window these more robust complex reflector attribute cubes can be combined with coherency and dip azimuth cubes using conventional geostatistical clustering and segmentation algorithms to provide an integrated multiattribute analysis

large spinel grains in a cm chondrite acfer 331 implications for reconstructions of ancient meteorite fluxes by dissolving 30400kg of marine limestone in hcl and hf acid our group has previously recovered common relict chromite grains approximately 63250m from ordinary chondritic micrometeorites that fell on ancient sea floors up to 500myr old here we evaluate if cm group carbonaceous chondritic material which makes up an important fraction of the micrometeorite flux today contains analogous grains that can be searched for in acid residues we dissolved 8g of cm2 meteorite acfer 331 in hf which yielded a characteristic assemblage of both transparent mg al and opaque cr spinels 28m we find on average 4 6 and 130 mg al spinel grains per gram in the 63250 and 2863m size fractions respectively these grains are mostly pink or colorless and often characterized by heterogeneous cr content black opaque cr spinel grains are absent from the 63m fraction but in the 2863m fraction we find approximately 65 such grains per gram meteorite the individual grains have a characteristic composition with heterogeneous major element compositions e g 44 461 7wt cr2o3 but narrow ranges for maximum tio2 0 61 6wt and v2o3 0 51 0wt concentrations the content of spinel grains in the 2863m fraction of cm meteorites appears comparable at the order of magnitude level with the content of 63m sized chromite grains in fossil l chondrites from ordovician limestone our approach of recovering meteoritic spinel from sediment may thus be extended to include cm meteorites but the smaller size fraction of the acid residues should be searched less

dynamics of fault interaction parallel strike slip faults we use a two dimensional finite difference computer program to study the effect of fault steps on dynamic ruptures our results indicate that a strike slip earthquake is unlikely to jump a fault step wider than 5 km in correlation with field observations of moderate to great sized earthquakes we also find that dynamically propagating ruptures can jump both compressional and dilational fault steps although wider dilational fault steps can be jumped dilational steps tend to delay the rupture for a longer time than compressional steps do this delay leads to a slower apparent rupture velocity in the vicinity of dilational steps these dry cases assumed hydrostatic or greater pore pressures but did not include the effects of changing pore pressures in an additional study we simulated the dynamic effects of a fault rupture on undrained pore fluids to test sibson s 1985 1986 suggestion that wet dilational steps are a barrier to rupture propagation our numerical results validate sibson s hypothesis by demonstrating that the effect of the rupture on the undrained pore fluids is to inhibit the rupture from jumping dilational stepovers the basis of our result differs from sibson s hypothesis in that our model is purely elastic and does not necessitate the opening of extension fractures between the fault segments

landslide susceptibility assessment in the hoa binh province of vietnam a comparison of the levenberg marquardt and bayesian regularized neural networks abstract this study investigates the potential application of artificial neural networks in landslide susceptibility mapping in the hoa binh province of vietnam a landslide inventory map of the study area was prepared by combining landslide locations investigated through three projects during the last 10 years some recent landslide locations were identified based on spot satellite images field surveys and existing literature the images have a spatial resolution of 2 5 m ten landslide conditioning factors were utilized in the multilayer feed forward neural network analysis slope aspect relief amplitude lithology land use soil type rainfall distance to roads distance to rivers and distance to faults two back propagation training algorithms levenberg marquardt and bayesian regularization were utilized to determine synoptic weights using a training dataset relative importance of each landslide conditioning factor was assessed using the above mentioned synoptic weights the final connection weights obtained in the training phase were applied to the entire study area to produce landslide susceptibility indexes the results were then imported to a gis and landslide susceptibility maps were constructed landslide locations not used in the training phase were used to verify and compare the results of the landslide susceptibility maps finally the two landslide susceptibility maps were validated using the prediction rate method subsequently areas under the prediction curves were assessed the prediction accuracy of landslide susceptibility maps produced by the bayesian regularization neural network and the levenberg marquardt neural network were 90 3 and 86 1 respectively these results indicate that the two models seem to have good predictive capability the bayesian regularization network model appears more robust and efficient than the levenberg marquardt network model for landslide susceptibility mapping

instantaneous spectral attributes to detect channels channels filled with porous rock and encased in a nonporousmatrixconstituteoneofthemoreimportantstratigraphic exploration plays although attributes such as coherence can be used to map channel width they are relatively insensitive to channel thickness in contrast spectral decomposition can beusedtomapsubtlechangesinchannelthickness thepeak spectral frequency derived by using the short window discrete fourier transform swdft is an excellent tool for mapping such changes along an interpreted horizon we show that by use of instantaneous spectral attributes we can generateequivalentmapsforcompleteseismicvolumes because we are often interested in mapping high reflectivity channelsencasedinalower reflectivitymatrix wefindthata composite plot of the peak frequency and the above average peak amplitude accentuates highly tuned channels finally by generating a composite volume using peak frequency peakamplitude andcoherence wecanestablishnotonlythe channelthickness butalsoitswidth wedemonstratethevalueofsuch3dvolumetricestimatesthroughapplicationto1 a marine survey acquired over tertiary channels from the gulfofmexicoand2alanddatasurveyacquiredoverpaleozoic channels from the central basin platform west texas united states the channels in both marine and land surveys canbehighlightedthroughcomposite volumeanalysis

fault steps and the dynamic rupture process 2 d numerical simulations of a spontaneously propagating shear fracture fault steps may have controlled the sizes of the 1966 parkfield 1968 borrego mountain 1979 imperial valley 1979 coyote lake and the 1987 superstition hills earthquakes this project investigates the effect of fault steps of various geometries on the dynamic rupture process we have used a finite difference code to simulate spontaneous rupture propagation in two dimensions we employ a slip weakening fracture criterion as the condition for rupture propagation and examine how rupture on one plane initiates rupture on parallel fault planes the geometry of the two parallel fault planes allows for stepover widths of 0 5 to 10 0 km and overlaps of 5 to 5 km our results demonstrate that the spontaneous rupture on the first fault segment continues to propagate onto the second fault segment for a range of geometries for both compressional and dilational fault steps a major difference between the compressional and dilational cases is that a dilational step requires a longer time delay between the rupture front reaching the end of the first fault segment and initiating rupture on the second segment therefore our dynamic study implies that a compressional step will be jumped quickly whereas a dilational step will cause a time delay leading to a lower apparent rupture velocity we also find that the rupture is capable of jumping a wider dilational step than compressional step

loading unloading response ratio theory applied in predicting deep seated landslides triggering abstract rainfall is the most relevant factor for the triggering of landslides and it is characterized by an extreme variability rainfall analysis is the most frequently adopted approach for predicting landslides but predicting deep seated landslides by means of rainfall thresholds is sometimes inadequate due to the complexity of such slopes in this paper further study of the loading unloading response ratio theory applied in landslides prediction was carried out as the aforementioned effect and character of rainfall was concerned a prediction for the known xintan landslide was carried out by means of the loading unloading response ratio method in which the action of water was regarded as loading unloading measures the results show that it is an effective method for landslides prediction and it has an advantage over conventional rainfall thresholds or time sequences analysis method

a hybrid machine learning model to estimate potential debris flow volumes abstract empirical statistical models of debris flow are challenging to implement in environments where sedimentary and hydrologic triggering processes change through time such as after a large earthquake the flexible and adaptive statistical methods provided by machine learning algorithms may improve the quality of debris flow predictions where triggering conditions and the nature of sediment that can bulk flows varies with time we developed a hybrid machine learning model of future debris flow volumes using a dataset of measured debris flow volumes from 60 catchments that generated post wenchuan earthquake mw 7 9 debris flows we input topographic variables catchment area topographic relief channel length distance from seismic fault and average channel gradient and the total volume of co seismic landslide debris into the pso elm adaboost machine learning model created by combining extreme learning machine elm particle swarm optimization pso and adaptive boosting machine learning algorithm adaboost the model was trained and tested using post 2008 mw 7 9 wenchuan earthquake debris flows then applied to understand potential volumes of post earthquake debris flows associated with other regional earthquakes 2013 mw 6 6 lushan earthquake 2010 mw 6 9 yushu earthquake we compared the pso elm adaboost method with different machine learning methods including back propagation neural network bpnn support vector machine svm elm pso elm the comparative analysis demonstrated that the pso elm adaboost method has a higher statistical validity and prediction accuracy with a mean absolute percentage error mape less than 0 10 the prediction accuracy of debris flow volumes trigged by other earthquakes decreases to 0 11 0 16 absolute percentage error suggesting that once calibrated for a region this method can be applied to other regional earthquakes this model may be useful for engineering design to mitigate the risk of large post earthquake debris flows

the relationship between late cenozoic tectonic events and stress field and basin development in northeast japan the regional tectonic stress field basin development and crustal deformation of the ne japan arc in the interval between 32 ma to the quaternary can be synthesized based on dike vein and fault orientation data as well as on the compilation of the regional geology an extensional stress field became prevalent from 32 ma and major normal faulting started at 25 20 ma which resulted from back arc rifting normal faulting trending nearly parallel to the arc propagated from the present japan sea coast to the forearc side following the trenchward migration of the main volcanic field from 20 to 15 ma normal faults with an oblique trend to the arc developed due to the counterclockwise rotation of ne japan the rapid clockwise rotation of sw japan since 16 ma produced a nw se directed transtensional stress regime in the ne japan arc due to crustal stretching associated with this pull apart movement the back arc side of the ne japan arc subsided rapidly to middle bathyal environments after the termination of the opening of the japan sea at about 14 ma a neutral stress regime prevailed which included phases of both weak extension and compression lithospheric cooling eventually led to thermal subsidence of the back arc region and igneous underplating caused uplift of the axial zone of the volcanic arc the increase in velocity of the westward motion of the pacific plate at around 4 ma produced strong compression across the arc reactivating most of the miocene normal faults and uplifting the volcanic arc the greatest crustal shortening occurred in areas that were stretched the most in the miocene within the volcanic arc which implies tectonic inversion

application of multi seismic attributes analysis in the study of distributary channels abstract during the exploration of stratigraphic reservoirs the key to locating these reservoirs is to identify the sandstone distribution seismic data can be used to recognize large scale distributary channel sedimentary bodies however depiction of sedimentary bodies in small distributary channels using traditional interpretation data from seismic profiles is extremely difficult in the upper cretaceous first sandstone bed of the third member of the nenjiang formation called the nen 3 member for simplicity in the xb area of the southern songliao basin distributary channels are the main sedimentary facies the distributary channels migrate frequently therefore it is difficult to precisely depict the morphology of the channel and the distribution of sandstone in this study we investigated the deposition of distributary channels using equal scale formation plane seismic attributes such as post stack amplitude instantaneous amplitude and seismic waveform classification analyzed well logging data from target formations and mapped the distribution of distributary channels this study shows that seismic sedimentological study and stacking multiple attribute analysis can identify the distribution of distributary channels precisely and effectively the attributes of equal scale strata slices are evidently superior to those of time and horizon slices attribute extraction and selection of equal scale formation slices is an essential step the comprehensive selection of seismic attributes that show a good correlation to a single well can be used to clearly depict channel bodies the overlap of the 40 hz single frequency energy and the rms amplitude depicts the sedimentary characteristics and shapes of sandstone bodies in main channels as well as small scale distributary channels more clearly than a single attribute these attributes show that the first sandstone bed of the nen 3 member was from distributary channels with complex shapes the distributary channels cut across each other vertically and laterally it indicates that during the deposition of the nen 3 member in xb area the direction of the main channel is from north to south and the provenance could be from north and east the method of this paper may provide some helpful suggestions to the geologist using seismic attributes to undertake research on sedimentary environment at other places in the world

3 d seismic discontinuity for faults and stratigraphic features the coherence cube seismic data are usually acquired and processed for imaging reflections this paper describes a method of processing seismic data for imaging discontinuities e g faults and stratigraphic features one application of this nontraditional process is a 3 d volume or cube of coherence coefficients within which faults are revealed as numerically separated surfaces figure 1 compares a traditional 3 d reflection amplitude time slice with the results of the new method to our knowledge this is the first published method of revealing fault surfaces within a 3 d volume for which no fault reflections have been recorded

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

use of backpropagation neural network for landslide monitoring a case study in the higher himalaya abstract this paper presents a case study of landslide monitoring and evaluation at okharpauwa 19 km chainage along kathmandu trishuli highway in nepal an attempt has been made to predict slope movements using backpropagation neural network bpnn a matlab based bpnn model is developed and the data from the case study are used to train and test the developed model to enable prediction of the magnitude of the ground movements with the help of input variables that have direct physical significance an infiltration coefficient is introduced in the network architecture apart from antecedent rainfall slope profile groundwater level and shear strength of soil a four layered backpropagation neural network with an input layer two hidden layers and one output layer is found optimal the developed bpnn model demonstrates a promising result and fairly accurately predicts the slope movement

a russian record of a middle ordovician meteorite shower extraterrestrial chromite at lynna river st petersburg region numerous fossil meteorites and high concentrations of sediment dispersed extraterrestrial chromite ec grains with ordinary chondritic composition have previously been documented from 467 1 6 ma middle ordovician darriwilian strata these finds probably reflect a temporarily enhanced influx of l chondritic matter following the disruption of the l chondrite parent body in the asteroid belt 470 6 ma in this study a volkhovian kundan limestone marl succession at lynna river northwestern russia has been searched for ec grains 63 mu m eight samples forming two separate sample sets were collected five samples from strata around the asaphus expansusa raniceps trilobite zone boundary in the lower middle kundan yielded a total of 496 ec grains in 65 5 kg of rock average 7 6 ec grains kg 1 but up to 10 2 grains kg 1 these are extremely high concentrations three orders of magnitude higher than background levels in similar condensed sediment from other periods ec grains are typically about 50 times more abundant than terrestrial chrome spinel in the samples and about as common as terrestrial ilmenite three stratigraphically lower lying samples close to the a lepidurusa expansus trilobite zone boundary at the volkhov kunda boundary yielded only two ec grains in 38 2 kg of rock 0 05 grains kg 1 the lack of commonly occurring ec grains in the lower interval probably reflects that these strata formed before the disruption of the l chondrite parent body the great similarity in ec chemical composition between this and other comparable studies indicates that all or most ec grains in these russian mid ordovician strata share a common sourcethe l chondrite parent body less

dynamics of thrust faulting 2d lattice model particle motions in a foam rubber model of shallow angle thrust faulting show many features different from those commonly assumed in dislocation models of subduction thrusts brune 1996 as a complement to a physical foam rubber experiment we have carried out dynamic simulation using a 2d lattice numerical model the model is constructed as a triangular block sliding over a rectangular elastic block it consists of a 2d set of particles interacting with each other by nonlinear hooke s forces and obeying newton s equations of motion rough surfaces are introduced on the contact plane of the two blocks to simulate realistic friction the numerical simulations demonstrate several key features of thrust faulting including stick slip fault opening and strong breakout and shaking at the hanging wall toe the wedge shaped tip of the outcropping hanging wall block of the thrust fault all consistent with the foam rubber experiments the stick slip motion shows an approximate time and slip repeatable behavior each slip event is characterized by a self healing pulse associated with fault opening and frictional locking the rupture pulse propagates steadily along the fault when rupture reaches the toe of the fault outcrop the hanging wall breaks away from the foot wall and creates a large opening vibration of the hanging wall the peak acceleration observed at the hanging wall toe of the fault outcrop is about 3 to 4 times the peak acceleration in the center part of the fault and about 2 to 3 times the motion of the foot wall such a large increase in peak acceleration at the toe is caused mainly by multiply reflecting stress waves trapped in the wedge shaped hanging wall of the fault the strong asymmetry of the particle velocity between the hanging wall and foot wall is an important feature of the results consistent with the foam rubber model but different from standard dislocation models this dynamic result illustrates the important effects of thrust faulting geometry on fault slip and ground motion

landslide susceptibility analysis based on arcgis and artificial neural network for a large catchment in three gorges region china a landslide susceptibility map is very important and necessary to efficiently prevent and mitigate the losses brought by natural hazard for a large area for the purpose of landslide susceptibility analysis for the whole xiangxi catchment 3 209 km2 artificial neural network ann analysis was applied as the main method the whole catchment was divided into two parts the training area and the implementation area the backwater area 559 km2 of xiangxi catchment was used as the training area for the ann method in the training area the correlations between the landslide distribution and its causative factors which includes lithology slope angle slope curvature and river network have been analyzed based on the geological map and digital elevation model dem the back propagation training algorithm in ann was selected to train the sample data from the training area which were composed of input data causative factors and target output data landslide occurrence in order to find the correlations between them based on these correlations and input data in the implementation area causative factors the network output data were obtained for the implementation area in the end a map of landslide susceptibility which was established by network output data was presented for xiangxi catchment arcgis was applied to extract and quantify input information from a dem for susceptibility analysis and also to present the result visually as a result a landslide susceptibility map in which 70 of all landslides are rightly classified in the training area backwater area was created for xiangxi catchment

a 3 d study of mineral inclusions in chromite from ordinary chondrites using synchrotron radiation x ray tomographic microscopy method and applications abstract a method is described for imaging in 3 d the interiors of meteoritic chromite grains and their inclusions using synchrotron radiation x ray tomographic microscopy in ordinary chondrites chromite is the only common mineral that survives long term weathering on earth information about the silicate matrix of the original meteorite however can be derived from mineral inclusions preserved in the protecting chromite the inclusions are crucial in the classification of fossil meteorites as well as sediment dispersed chromite grains from decomposed meteorites and larger impacts as these are used for characterizing the past influx of material to earth but have previously been difficult to locate the method is non destructive and time efficient for locating inclusions the method allowed quantitative and morphological studies of both host chromite grains and inclusions in three dimensions the study of 385 chromite grains from eight chondrites h4 6 l4 6 ll4 ll6 reveals that inclusions are abundant and equally common in all samples almost two thirds of all chromite grains contain inclusions regardless of group and type the study also shows that the size of the inclusions and the host chromite grains as well as the number of inclusions within the host chromite grains vary with petrographic type thus the petrographic type of the host of a suite of chromite grains can be determined based solely on inclusion content the study also revealed that the amount of fractures in the host chromite can be correlated to previously assigned shock stages for the various chondrites the study has thus shown that the features and inclusions of fossil chromite grains can give similar information about a former host meteorite as do studies of an unweathered whole meteorite meaning that this technique is essential in the studies of ancient meteorite flux to earth