indicators of aqueous alteration in cm carbonaceous chondrites microtextures of a layered mineral containing fe s o and ni a petrographic and transmission electron microscopy study of the mighei murchison and murray cm carbonaceous chondrites shows that much of the cm matrix material was probably produced by aqueous alteration of olivine pyroxene sulfide and metal the amount of cm matrix appears to be proportional to the degree of alteration as suggested by mcsween 1979 and microtextures of pcp poorly characterized phase provide evidence of the progressive alteration pcp is divided into two major types one occurs in chondrules and aggregates and consists largely of an fe ni s o phase type i and the other occurs in matrix and consists of the fe ni s o phase and cronstedtite in various proportions type ii microtextures of pcp suggest that it resulted from a three stage alteration process 1 1 type i was produced by alteration of kamacite in chondrules and aggregates presumably early in the parent body regolith 2 2 as the alteration advanced olivine and pyroxene were converted to serpentine type i pcp separated from chondrules and aggregates into the matrix during regolith gardening simultaneously the fe ni s o phase reacted with si released by alteration of olivine and pyroxene producing well formed platy cronstedtite and coherent intergrowths of the fe ni s o phase and cronstedtite the fe ni s o phase also recrystallized into platy and pod like crystals fe s ni cr and p were leached out of type i pcp and were deposited as small grains of fe ni sulfides magnetite chromite and a mineral unidentified containing fe ni cr and p as a result pcp came to consist primarily of the fe ni s o phase and cronstedtite i e type ii pcp 3 3 during continued alteration the well formed crystals of the fe ni s o phase cronstedtite and their intergrowths in type ii pcp were replaced by poorly formed fibers in comparison to other cm chondrites mighei murchison and murray are relatively unaltered their matrices retain abundant amounts of the fe ni s o phase and cronstedtite commonly as distinctive pcp grains which account for a large proportion of the fe in these meteorite matrices in more altered cm chondrites much of the fe ni s o phase was probably consumed to produce cronstedtite magnetite and sulfides with further alteration cronstedtite itself reacted with the serpentine to form ferroan serpentine thus the cm matrix was increasingly enriched in mg with alteration and pcp was increasingly degraded and intimately mixed with the magnesian phyllosilicates

simplified method for evaluating seismic stability of steep slopes steep slopes composed of weakly cemented granular soils are common along the pacific coast of north america these slopes standing at angles of 30 to near vertical are observed to be prone to seismically induced failures the steep topography of these slopes makes them particularly susceptible to amplification of seismic waves and the brittle nature of these materials make deformation based stability analyses inappropriate in this paper a simplified method is presented for assessing the seismic stability of these slopes utilizing average seismic coefficients to account for the effect of topography this procedure is based on a review of field and laboratory observations as well as analyses carried out using generalized consistent transmitting boundaries the results of the analyses indicate that the amplification due to the soil column in the free field behind the crest dominates the response the amplification due to topography on the other hand shows little variability and is on the order of 50 the proposed procedure presented herein gives practicing engineers a method to conduct stability analyses that better represents the actual field conditions for these steep brittle slopes

infrared spectroscopic taxonomy for carbonaceous chondrites from speciation of hydrous components mid infrared absorption spectra for all types of carbonaceous chondrites were obtained in this study to establish a versatile method for spectroscopic classification of carbonaceous chondrites infrared spectra were measured using a conventional kbr pellet method and diamond press method spectra of hydrous carbonaceous chondrites exhibit intense o h stretching vibrations ci chondrites are identifiable by a characteristic sharp absorption band appearing at 3685 cm 1 which is mainly attributable to serpentine x ray diffraction analysis showed the presence of serpentine however yamato y 82162 c1 does not have the band at 3685 cm 1 because of its thermal metamorphism cm and cr chondrites have an intense absorption band at approximately 3600 cm 1 this absorption tends to appear in cm chondrites more strongly than cr chondrites because the intensity ratios of an oh stretching mode at 3520 cm 1 compared to 3400 cm 1 for cm chondrites are in the range of 0 95 1 04 which is systematically higher than those of cr chondrites 0 86 0 88 therefore the two types of chondrites are distinguishable by their respective infrared spectra the spectrum feature of the tagish lake meteorite is attributable to neither ci nor cm chondrites co chondrites are characterized by weak and broad absorption at 3400 cm 1 cv chondrites have weak or negligible absorption of water ck chondrites also have no water induced absorption ch and cb chondrites have a sharp absorption at 3692 cm 1 indicating the presence of chrysotile which is also supported by observations of x ray diffraction and tem the combination of spectroscopic classification and the diamond press method allows classification of carbonaceous chondrites of very valuable samples with small quantities as one example carbonaceous chondrite clasts in brecciated meteorites were classified using our technique infrared spectra for a fragment of carbonaceous clasts 1 g separated from willard b and tsukuba were measured the 3685 cm 1 band found in ci chondrites was clearly detected in the clasts indicating that they are ci like clasts

seismic site amplification induced by topographic irregularity results of a numerical analysis on 2d synthetic models abstract this study concerns the evaluation of seismic site effects and their relation to the local topographical characteristics of a slope the seismic amplification sa on the free surface is calculated by a numerical model using the finite elements fe method synthetic models by utilized in the fe analysis represent a slope with an inclination ranging from 10 to 41 at the crest and valley of the slope the models were considered horizontal and indefinite the site effects were calculated on the free surface in several nodal points the input motion used in the analysis was a sv seismic wave with variable frequency between 0 5 and 32 hz the seismic site analysis confirmed that in absence of sediments ground motion is more amplified at the upper slope break than in other points of the model in regard to seismic amplification vs the frequency we can affirm that seismic amplification reaches its maxima in the band 4 16 hz and with slope angle value computed at the highest degree it is also clear that a nonlinear seismic amplification response in the crest and valley zone while sa would seem to have a linear response in other zones we propose an empirical method to estimate the sa in the regular slope far from the crest and valley zone

total load transport in alluvial channels a relationship for computation of total load transport in alluvial channels has been developed by analysis of extensive data from rivers and canals and from laboratory studies the relationship is extremely simple and is based on logicalpremises the accuracy of computation of total load from this relationship is quite good in comparison to that obtained from some of the existing relationships

oxygen isotope studies of carbonaceous chondrites abstract the carbonaceous chondrites display the widest range of oxygen isotopic composition of any meteorite group as a consequence of the interaction of primordial isotopic reservoirs in the solar nebula these isotopic variations can be used to identify the reservoirs and to determine conditions and loci of their interactions we present a comprehensive set of whole rock analyses of cv co ck cm cr ch and ci chondrites as well as selected components of some of these meteorites a simple model is developed which describes the isotopic behavior during parent body aqueous alteration processes the process of thermal dehydration also produces a recognizable effect in the oxygen isotopic composition

plio quaternary uplift rates in the outer zone of the central apennines fold and thrust belt italy abstract geological seismic and borehole data permitted the reconstruction of the plio quaternary uplift subsidence and erosion sedimentation history for the outer sector of the central apennines during the latest contractional stages middle late pliocene the frontal sector of the belt experienced a net subsidence locally compensated by the growth of the fold and thrust system this tectonic uplift was localized at the axial culmination of the anticlines and particularly for the major structures was responsible for exhumation and erosion of the neogene succession and for near flat planation surfaces development on meso cenozoic carbonate rocks at the crest of the anticlines since the early middle pleistocene a regional doming involved the outer part of the belt peri adriatic domain this process interacted with quaternary eustatic sea level fluctuations and caused the basinward migration of shallow marine deposits forming an overall prograding system quaternary shoreline retreat base level drop and climatic changes were mainly associated with valley deepening and fluvial terrace formation the present study outlines that fold thrust growth and regional doming driving processes characterized by different amplitude wavelength and uplift rate amounts are both responsible for the morphological setting of the central apennines external zones

mineralogical and spectroscopic investigation of the tagish lake carbonaceous chondrite by x ray diffraction and infrared reflectance spectroscopy abstract we have carried out a sample correlated spectroscopic and mineralogical investigation of samples from seven different collection sites of the tagish lake c2 chondrite rietveld refinement of high resolution powder x ray diffraction xrd data was used to determine quantitative major mineral abundances thermal infrared 400 4500 cm 1 2 2 25 0 m spectra of the same samples were obtained using diffuse biconical reflectance infrared fourier transform spectroscopy drifts our results are in good agreement with previous studies of the mineralogy of the tagish lake meteorite we find however that tagish lake is more varied in major mineralogy than has previously been reported in particular we observed two new distinct lithologies an inclusion poor magnetite and sulfide rich lithology and a carbonate rich siderite dominated lithology in addition to the previously documented carbonate rich and carbonate poor lithologies grain density for each tagish lake sample was calculated from the measured mineral modal abundances and known mineral densities for powders from three originally intact inclusion rich samples the calculated grain density is 2 77 0 05 g cm 3 in excellent agreement with those reported in the literature for other intact inclusion rich tagish lake samples tagish lake disaggregated samples have a significantly higher calculated grain density due to their lower saponite serpentine content likely a result of mineral separation in the meltwater holes from which they were collected the disaggregated samples may not therefore adequately represent bulk samples of the tagish lake meteorite the predominance of very fine grained material in the tagish lake samples investigated in this study is expected to produce infrared spectra representative of asteroidal regolith gypsum and talc have been found by xrd in powders from the inclusion rich intact tagish lake samples in this study and may have been present in the parent body if present these hydrous sulfates would complicate the interpretation of possible hydrated mineral features in asteroid infrared spectra

the oxygen isotopic composition of olivine and pyroxene from ci chondrites the ci chondrites are taken to represent average solar system material based on the similarity of their elemental compositions to that of the solar photosphere however their oxygen isotope geochemistry is dominated by secondary minerals that formed during aqueous alteration on the ci parent body precursors to this alteration namely olivine and pyroxene are extremely rare in ci chondrites precluding previous measurements of their oxygen isotopic composition we report ion microprobe analyses of oxygen isotopes in single olivine and pyroxene grains separated from ci chondrites orgueil and ivuna the ci chondrite olivine and pyroxene grains most likely represent liberated chondrule phenocrysts based on petrographic chemical and isotopic evidence consistent with crystallization from a melt the oxygen isotope data form an array that falls nearly along the carbonaceous chondrite 16o mixing line with 18o values ranging from 9 3 to 12 3 o and 17o from 11 3 o to 7 8 o consistent with nebular processes being the source of the oxygen isotopic compositions the degree of 16o enrichment in orgueil olivines is negatively correlated with feo content but the exact nature and timing of the process that introduced this variation remains unknown the pyroxene oxygen isotopic compositions are similar to those of olivines with 5 mol fayalite the oxygen isotopic analyses of the olivine and pyroxene in ci chondrites have been used to revise previous models for the isotopic evolution of ci materials our data require more complete gas solid equilibration in the nebula and constrain the initial aqueous fluids on the ci parent body to have lower 17o values than previously postulated the refined model indicates that the temperature of aqueous activity on the ci parent body was no higher than 50 c and the fluid rock ratio was significantly less than previously estimated even prior to alteration and formation of secondary minerals the ci chondrites were the most 16o depleted carbonaceous chondrites and thus the solids originally contained in the ci chondrites are the most equilibrated nebular materials represented in the carbonaceous chondrites the data suggest the oxygen isotopic composition of average solar system to be approximately equivalent to average terrestrial oxygen as recorded in the compositions of terrestrial and lunar basalts

the thick bedded tail of turbidite thickness distribution as a proxy for flow confinement examples from tertiary basins of central and northern apennines italy this study reviews the thickness statistics of non channelized turbidites from four tertiary basins of central northern apennines italy where bed geometry and sedimentary character have been previously assessed though very different in terms of size and arguably character of feeder system these basins share a common stratigraphic evolution consisting in transition from an early ponded to a late unconfined setting of deposition based on comparison of thickness subsets from diverse locations and stratigraphic heights within the studied turbidite fills this paper seeks to answer the following questions i how data collection procedures and field operational constraints e g measure location outcrop quality use of thicknesses data from single vs multiple correlative sections stratigraphic thickness of the study interval can affect statistics of sample data ii how depositional controls of confined vs unconfined turbidite basins can result in different thickness frequency distributions and iii is there in thickness statistics a flow confinement signature which can be used to distinguish between confined and unconfined turbidites results suggest that i best practices of data collection are crucial to a meaningful interpretation of sample data statistics especially in presence of stratigraphic and spatial trends of turbidite bed thickness ii a systematic bias against cm thick tcd bouma sequence turbidites exists in sample data which can result in the low end tail of empirical thickness frequency distributions to depart significantly from the actual distribution of turbidite thickness and iii thickness statistics of beds starting with a basal ta tb bouma division bear a coherent relationship to the transition from ponded to unconfined depositional settings consisting in reduction of variance and mean and consequently parameters or even type of best fit model distribution this research highlights the role of flow stripping sediment by pass and bed geometry in altering the initial thickness distribution of ponded turbidites and suggests how fully ponded mini basins represent the ideal setting for further research linking turbidite thickness statistics and frequency distribution of parent flow volumes

mid infrared spectroscopy of refractory inclusions cais in cv and co chondrites we present laboratory mid infrared absorption spectra 2 5 m to 16 0 m of powdered calcium aluminum rich inclusions cais and matrix separated from the carbonaceous chondrites allende cv3 2 vigarano cv3 3 and ornans co3 3 two groups of spectra with different features were found for the cai in the first group spectra are dominated by spinel pyroxene and sodalite nepheline where main features occur at 9 3 m 10 3 m and 11 3 m in the second group characteristic minerals are spinel and melilite with typical band maxima at 11 0 m and 12 3 m and a broad feature between 14 0 m and 15 0 m the position of the broad spinel feature probably depends on its iron content comparison of band positions in spectra from the cai components to observed circumstellar emission spectra indicates the potential occurrence of cai like material pyroxene and spinel rich features could occur in spectra of dust around the herbig ae star hd104237 the t tauri star hen3 600 and the post agb star r sge melilite and spinel rich components possibly appear in the spectrum of hd104237 hen3 600 04187 1927 r sge and the planetary nebula hb 12 there is also indication for a spinel component in dust from the herbig ae be star hd179218 the spectra of the agb stars r cas and aps show no features of cai type spinel

structural control on the directional amplification of seismic noise campo imperatore central italy abstract seismic signals propagating across a fault may yield information on the internal structure of the fault zone here we have assessed the amplification of seismic noise i e ambient vibrations generated by natural or anthropogenic disturbances across the vado di corno fault campo imperatore central italy the fault zone is considered as an exhumed analogue of the normal faults activated during the l aquila 2009 earthquake sequence detailed structural geological survey of the footwall block revealed that the fault zone is highly anisotropic and is affected by a complex network of faults and fractures with dominant wnw ese strike we measured seismic noise with portable seismometers along a 500 m long transect perpendicular to the average fault strike seismic signals were processed calculating the horizontal to vertical spectral ratios and performing wavefield polarization analyses we found a predominant ne sw to nne ssw i e ca perpendicular to the average strike of the fault fracture network amplification of the horizontal component of the seismic waves numerical simulations of earthquake induced ground motions ruled out the role of topography in controlling the polarization and the amplitude of the waves therefore the higher seismic noise amplitude observed in the fault perpendicular direction was related to the measured fracture network and the resulting stiffness anisotropy of the rock mass these observations open new perspectives in using measures of ambient seismic noise which are fast and inexpensive to estimate the dominant orientation of fracture networks within fault zones

modified topographic amplification factors for a single faced slope due to kinematic soil structure interaction in this paper we evaluate the additive effects of topography soil nonlinearity and soil structure interaction ssi along the crest of an idealized 40 m high cliff type topographic feature with slope inclination 300 where excessive damage was observed during the athens 1999 earthquake the objective of this paper is to investigate the relative contribution of topographic amplification and kinematic ssi as a function of the incident motion frequency content and geotechnical site conditions for a surface and an embedded structure located at the cliff crest for this purpose we perform elastic parametric and nonlinear site specific two dimensional finite element simulations using three profiles and six input motions we illustrate the role of ssi in altering the response at the location of peak topographic amplification potential behind the crest the effects of incident motion incoherency on the transient structural response and the beneficial contribution of structural embedment we finally suggest that empirical models for base slab averaging of shallow foundations developed as a function of site conditions structural dimensions and center line location could be combined with topographic amplification factors to predict realistic design spectra for structures located on irregular topographic features

wavefield polarization in fault zones of the western flank of mt etna observations and fracture orientation modelling ambient noise measurements performed on the western flank of mt etna are analyzed to infer the occurrence of directional amplification effects in fault zones the data were recorded along short 500 m profiles crossing the ragalna fault system ambient noise records were processed to compute the horizontal to vertical noise spectral ratio as a function of frequency and direction of motion wavefield polarization was investigated in the time frequency domain as well peaks of the spectral ratios generally fall in the frequency band 1 0 6 0 hz pointing out directional amplifications that are also confirmed by the results of the time frequency analysis the largest amplification occurring with high angle to the fault strike a variation of the frequency of the spectral peak is observed between the two sides of the fault possibly related to a damage fault asymmetry measurements performed several kilometers away from the fault zone do not show behavior that is as systematic as in the fault zone and this suggests that the observed directional effects can be ascribed to the fault fabric we relate the polarization effect to compliance anisotropy in the fault zone where the presence of predominantly oriented fractures makes the normal component of ground motion larger than the transversal one in order to test the direction and the type of fractures that are expected in the fault zone we modeled the brittle deformation pattern of the investigated fault theoretical results are in good agreement with field observations of the fracture strike

acfer 182 and paired samples an iron rich carbonaceous chondrite similarities with alh85085 and relationship to cr chondrites three samples of a new fe rich chondrite were found in the sahara in 1990 and 1991 acfer 182 acfer 207 acfer 214 the samples are paired and the meteorite will be designated as acfer 182 the chondrite is chemically texturally and mineralogically similar to the allan hills meteorite alh85085 one important difference between the two meteorites is the smaller average chondrule size in alh85085 the major components of acfer 182 in decreasing abundance are 1 1 highly altered by terrestrial weathering matrix 2 2 mineral and polymineralic silicate fragments and aggregates 3 3 chondrule fragments 4 4 chondrules 5 5 metal 6 6 fine grained dark inclusions the abundance of chondrules is lower and the average chondrule size 90 m smaller than in most other chondrites chondrule fragments are often so large that they cannot be derived from the present chondrule population apparently size sorting has prevented accumulation of the larger parent chondrules several spectacular ca al rich inclusions were found rich in ca dialuminate hibonite or zr y sc bearing phases the chemical composition of acfer 182 and of alh85085 are almost indistinguishable major chemical signatures are 1 1 uniform enrichment of fe and other nonvolatile metals relative to ci chondrites by about 70 2 2 absence of enrichment in refractory lithophiles characteristic of most type 2 and 3 carbonaceous chondrites 3 3 strong depletion of volatile and moderately volatile elements based on the oxygen isotopic composition the chemical composition and the abundances of chondrules and matrix acfer 182 should be classified as a carbonaceous chondrite considering their affinity to carbonaceous chondrites and their high bulk iron content the two meteorites acfer 182 and alh85085 are designated as ch chondrites there are mineralogical and chemical similarities among acfer 182 alh85085 and cr chondrites which distinguish these meteorites from other types of carbonaceous chondrites 1 1 low feo contents of olivine and pyroxene and correspondingly high metal contents 2 2 high cr content in olivine 3 3 abundant fine grained dark inclusions 4 4 abundant ca dialuminate caal4o7 in cais 5 5 similarities in oxygen isotopic composition 6 6 low contents of moderately volatile elements 7 7 low refractory element contents 8 8 presence of a unique component of subsolar rare gases these observations suggest similar conditions of formation for the components of these meteorites a single common parent body is unlikely in view of the differences in chemical composition and in the size distribution of individual components

modeling aqueous alteration of cm carbonaceous chondrites results from an inorganic geochemical modeling study support a scenario in which low temperature aqueous alteration of an anhydrous cm asteroidal parent body and melt water from h20 and co ices produces the altered assemblage observed in cm carbonaceous chondrites chrysotile greenalite tochilinite cronstedtite and minor calcite and magnetite we consider a range of possible precursor mineral assemblages varying with respect to the fe oxidation state of the initial anhydrous phases the aqueous solutions produced by this alteration are generally strongly basic and reducing and a large quantity of h2 and possible ch4 gas can be released during aqueous alteration

topographical and geological amplifications determined from strong motion and aftershock records of the 3 march 1985 chile earthquake site response experiments were performed 5 months after the ms 7 8 central chile earthquake of 3 march 1985 to identify amplification due to topography and geology topographical amplification at canal beagle a subdivision of vina del mar was hypothesized immediately after the main event when extensive damage was observed on the ridges of canal beagle using frequency dependent spectral ratios of aftershock data obtained from a temporarily established dense array it is shown that there is substantial amplification of motions at the ridges of canal beagle the data set constitutes the first such set depicting topographical amplification at a heavily populated region and correlates well with the damage distribution observed during the main event dense arrays established in vina del mar also yielded extensive data which are quantified to show that in the range of frequencies of engineering interest there was substantial amplification at different sites of different geological formations to substantiate this spectral ratios developed from the strong motion records of the main event are used to show the extensive degree of amplification at an alluvial site as compared to a rock site similarly spectral ratios developed from aftershocks recorded at comparable stations qualitatively confirm that the frequency ranges for which the amplification of motions occur are quite similar to those from strong motion records in case of weak motions the denser arrays established temporarily as described herein can be used to identify the frequency ranges for which amplification occurs to quantify the degree of frequency dependent amplification and used in microzonation of closely spaced localities

mineralogy of tagish lake an ungrouped type 2 carbonaceous chondrite in this paper we describe the recovery handling and preliminary mineralogical investigation of the tagish lake meteorite tagish lake is a type 2 carbonaceous chondrite which bears similarities to ci1 and cm chondrite groups but is distinct from both abundant phyllosilicates as well as chondrules however sparse and common olivine grains in the matrix preclude any other classification the bulk density of tagish lake 1 67 g cc which is far lower than ci or cm chondrites 2 2 2 3 and 2 6 2 9 g cc respectively or any other meteorite for that matter we have identified two lithologies a dominant carbonate poor lithology and a less abundant carbonate rich lithology the meteorite is a breccia at all scales we have noted similarities between tagish lake and some clasts within the enigmatic meteorite kaidun possibly there are genetic relationships here worth exploring in the paper we describe a clast of cm1 material within tagish lake which is very similar to a major lithology in kaidun

small is beautiful upscaling from microscale laminar to natural turbulent rivers 1 the use of microscale experimental rivers with flow depths of the order of a few millimeters to investigate natural processes such as alluvial fans dynamics knickpoints migration and channel morphologies such as meandering and braiding has become increasingly popular in recent years this raises the need to address the issue of how to extrapolate results from the experimental microscale at which flow is laminar to the scale of natural turbulent rivers we address this question by performing measurements of average flow velocity and sediment transport in an experimental laminar river the average flow velocity is correctly predicted from the navier stokes equation solved for a steady uniform laminar flow laminar sediment transport is found to be consistent with the law of meyer peter and muller 1948 commonly used to describe sediment transport in natural turbulent rivers we also show that surface tension is important only if the microscale river width is on the order of or smaller than the capillary length these results allow us to demonstrate that the evolution of longitudinal bed profiles of turbulent and laminar rivers are governed by identical dimensionless equations and therefore follow the same dynamics differences of time and length scales at work in experimental and natural rivers are mainly encoded in the expression of two parameters a diffusion coefficient and a threshold slope on the basis of this analysis we derive a set of equations allowing us to rescale bed elevation downstream distance time and uplift rate from an experimental microscale river to the field scale finally we show how this set of equations can be used to rescale these same parameters in the case of a temporally varying discharge

heavily hydrated lithic clasts in ch chondrites and the related metal rich chondrites queen alexandra range 94411 and hammadah al hamra 237 fine grained heavily hydrated lithic clasts in the metal rich cb chondrites queen alexandra range que 94411 and hammadah al hamra 237 and ch chondrites such as patuxent range pat 91546 and allan hills alh 85085 are mineralogically similar suggesting genetic relationship between these meteorites these clasts contain no anhydrous silicates and consist of framboidal and platelet magnetite prismatic sulfides pentlandite and pyrrhotite and fe mn mg bearing ca carbonates set in a phyllosilicate rich matrix two types of phyllosilicates were identified serpentine with basal spacing of similar to0 73 nm and saponite with basal spacings of about 1 1 1 2 nm chondrules and feni metal grains in cb and ch chondrites are believed to have formed at high temperature 1300 k by condensation in a solar nebula region that experienced complete vaporization the absence of aqueous alteration of chondrules and metal grains in cb and ch chondrites indicates that the clasts experienced hydration in an asteroidal setting prior to incorporation into the ch and cb parent bodies the hydrated clasts were either incorporated during regolith gardening or accreted together with chondrules and feni metal gains after these high temperature components had been transported from their hot formation region to a much colder region of the solar nebula

searching for the source regions of martian meteorites using mgs tes integrating martian meteorites into the global distribution of igneous materials on mars the objective of this study was to identify and map possible source regions for all 5 known martian meteorite lithologies basalt lherzolite clinopyroxenite orthopyroxenite and dunite using data from the mars global surveyor thermal emission spectrometer mgs tes we deconvolved the tes data set using laboratory spectra of 6 martian meteorites los angeles zagami alh a77005 nakhla alh 84001 and chassigny as end members along with atmospheric and surface spectra previously derived from tes data global maps 16 pixels degree of the distribution of each meteorite end member show that meteorite like compositions are not present at or above tes detectability limits over most of the planet s dust free regions however we have confidently identified local scale 100s1000s km2 concentrations of olivine and orthopyroxene bearing materials similar to alh a77005 chassigny and alh 84001 in nili fossae in and near ganges chasma in the argyre and hellas basin rims and in eos chasma nakhla like materials are identified near the detection limit throughout the eastern valles marineris region and portions of syrtis major basaltic shergottites were not detected in any spatially coherent areas at the scale of this study martian meteorite like lithologies represent only a minor portion of the dust free surface and thus are not representative of the bulk composition of the ancient crust meteorite like spectral signatures identified above tes detectability limits in more spatially restricted areas tens of km are targets of ongoing analysis

topographic effects on the seismic response of steep slopes a frequency domain parametric study using generalized consistent transmitting boundaries has been performed to evaluate the significance of topographic effects on the seismic response of steep slopes the results show that the peak amplification of motion at the crest of a slope occurs at a normalized frequency h 0 2 where h is the slope height and is the wavelength of the motion the importance of the natural site frequency is illustrated by the analysis of a stepped layer over a half space it was found that the natural frequency of the region behind the crest can dominate the response relative to the topographic effect for the conditions studied moreover the effect of topography can be handled separately from the amplification due to the natural frequency of the deposit behind the crest of the slope this concept of separating the amplification caused by topography from that caused by the natural frequency is advantageous to the development of a simplified method to estimate topographic effects

statistical approach to earthquake induced landslide susceptibility susceptibility analysis for predicting earthquake induced landslides has most frequently been done using deterministic methods multivariate statistical methods have not previously been applied in this study however we introduce a statistical methodology that uses the intensity of earthquake shaking as a landslide triggering factor this methodology is applied in a study of shallow earthquake induced landslides in central western taiwan the results show that we can accurately interpret landslide distribution in the study area and predict the occurrence of landslides in neighboring regions this susceptibility model is capable of predicting shallow landslides induced during an earthquake scenario with similar range of ground shaking without requiring the use of geotechnical groundwater or failure depth data

seismically induced rock slope failures resulting from topographic amplification of strong ground motions the case of pacoima canyon california abstract the 1994 northridge earthquake mw 6 7 triggered extensive rock slope failures in pacoima canyon immediately north of los angeles california pacoima canyon is a narrow and steep canyon incised in gneissic and granitic rocks peak accelerations of nearly 1 6 g were recorded at a ridge that forms the left abutment of pacoima dam peak accelerations at the bottom of the canyon were less than 0 5 g suggesting the occurrence of topographic amplification topographic effects have been previously suggested to explain similarly high ground motions at the site during the 1971 mw 6 7 san fernando earthquake furthermore high landslide concentrations observed in the area have been attributed to unusually strong ground motions rather than higher susceptibility to sliding compared with nearby zones we conducted field investigations and slope stability back analyses to confirm the impact of topographic amplification on the triggering of landslides during the 1994 earthquake our results suggest that the observed extensive rock sliding and falling would have not been possible under unamplified seismic conditions which would have generated a significantly lower number of areas affected by landslides in contrast modelling slope stability using amplified ground shaking predicts slope failure distributions matching what occurred in 1994 this observation confirms a significant role for topographic amplification on the triggering of landslides at the site and emphasises the need to select carefully the inputs for seismic slope stability analyses

the application of finite element analysis to body wave propagation problems summary the finite element method is shown to be a powerful tool for the numerical modelling of seismic body wave propagation problems applications extend to both problems on a scale of interest to engineers and also to large scale seismological problems solutions are sought in the time domain efficient programs have been written to accomplish this the scope of numerical solutions has been greatly enhanced by the use of a previously reported scheme for exactly cancelling reflections at the boundaries of the model the finite difference results of boore and the analytical results of trifunac for the amplification due to a mountain and an alluvial valley respectively are compared with new finite element results the new results agree well although there are some difficulties with resonance in the alluvial valley problem boore s sh results have been extended to vertical p and sv incidence a deep earthquake zone has been modelled realistically in two dimensions and earthquakes simulated at depth it is suggested that the variation in observed amplitude across the top of the zone due to refraction away from the slab may be used to provide an estimate of the thickness of the slab from long period observations of local earthquakes

hydration bands near 3 μm and weathering of some antarctic meteorites abstract we studied the degree of weathering of some antartctic meteorites using the integrated intensity of absorption bands hydration bands near 3 m due to the presence of hydrous minerals the allan hills meteorites measured show stronger integrated intensities than the yamato meteorites measured although the number of meteorites we measured is small this suggests that the allan hills meteorites are more weathered than the yamato meteorites the allan hills meteorites show greater terrestrial ages than other antarctic meteorites on the basis of cosmic ray produced nuclide data our results are consistent with the terrestrial age data because weathering produces hydrous minerals integrated intensities near 3 m vary widely among the antarctic meteorites reported to be relatively little weathered under microscopic observation the integrated intensity of hydration bands near 3 m may have the potential for quantifying the degree of weathering these quantified data may help in selecting less weathered meteorites from among the antarctic meteorite collection and may be combined with terrestrial age data to study terrestrial histories of antarctic meteorites

mineralogy and noble gas signatures of the carbonate rich lithology of the tagish lake carbonaceous chondrite evidence for an accretionary breccia abstract the carbonate rich lithology of the tagish lake carbonaceous chondrite was characterized by noble gas mass spectrometry synchrotron x ray diffraction analysis and transmission and scanning electron microscopy noble gas analysis was performed on two samples and the results showed that primordial noble gases are abundant and solar noble gases are absent in the samples of carbonate rich lithology the concentrations of ne a2 and e in both samples are at the maximum level observed for ci and cm chondrites suggesting high abundances of presolar diamonds and sic graphite respectively the cosmic ray exposure age cannot be determined precisely because the shielding depth of our tagish lake samples is unknown but the minimum exposure age was determined to be 5 5 0 7 myr on the basis of cosmogenic 21ne concentrations and the highest 21ne production rate x ray and electron microscopic study showed that the carbonate rich lithology is dominated by loosely packed porous matrix that consists mainly of fine grained saponite and ferromagenesian carbonate the matrix contains very few chondrules but many fine grained clasts having angular shape with longest dimensions up to 1 mm the clasts differ from host matrix in both texture and mineralogy they are massive compacted material with porosity much lower than matrix and contain abundant magnetite and a coherent intergrowth of serpentine and saponite that is rare in matrix the presence of texturally and mineralogically distinct clasts indicates that the carbonate rich lithology is a breccia but the absence of solar noble gases and impact induced deformational features in host matrix distinguish it from an asteroid regolith breccia our results instead indicate that it is an accretionary breccia formed by simultaneous accretion of diverse objects in a massive dust cloud the clasts often enclose chondrules and anhydrous silicate fragments such as low iron manganese enriched olivines this observation and their highly compacted angular morphology suggests that the clasts derive from earlier formed chondritic materials which have experienced compression and fragmentation due to mild impacts and from which they were excavated and incorporated into the final rock it is thus suggested that in the course of planetesimal formation agglomeration and disagglomeration of small parent bodies occurred repeatedly in a dense dust cloud where solar wind from the infant sun was shielded the fine grained ferromagnesian carbonates must have precipitated from aqueous solutions after the assembly of the tagish lake asteroid from recycled materials from previous bodies because the carbonates coat the surfaces of pores and fill in veins in the clasts

mineralogy and composition of matrix and chondrule rims in carbonaceous chondrites abstract the degree of compositional variation of fine grained minerals displayed by the members within any carbonaceous chondrite group i e ci cm cv cr is a direct reflection of the range of aqueous alteration assemblages present matrix and fine grained chondrule rims within any particular carbonaceous chondrite are mineralogically nearly identical to one another but not necessarily similar in bulk elemental composition even though they have subsequently experienced post accretional secondary processing aqueous alteration under identical conditions this may indicate preferential alteration of one component brecciation exchange of components between rims and matrix and or accretion of matrix and rims from mineralogically or compositionally distinct materials we propose that co chondrites experienced parent body conditions of low f o2 low water rock ratios and temperatures below 50 c cr chondrites experienced higher water rock ratios potentially higher temperatures 150 c and a wide range of f o2 the alteration mineralogy of cv chondrites indicates water rock ratios at the high end at least of the range for cr chondrites essebi and mac 87300 cm chondrites experienced temperatures below 50 c low f o2 and low water rock ratios except eet 83334 which probably experienced relatively higher f o2 and b 7904 and y 86720 which experienced postalteration temperatures in the range 500 700 c most ci chondrites experienced temperatures between 50 and 150 c relatively high water rock ratios and variable f o2 with a late stage increase in the latter due possibly to brecciation and consequent release of methane y 82162 witnessed post alteration heating possibly as high as 400 c

toward real time regional earthquake simulation ii real time online earthquake simulation ros of taiwan earthquakes abstract we developed a real time online earthquake simulation system ros to simulate regional earthquakes in taiwan the ros uses a centroid moment tensor solution of seismic events from a real time moment tensor monitoring system rmt which provides all the point source parameters including the event origin time hypocentral location moment magnitude and focal mechanism within 2 min after the occurrence of an earthquake then all of the source parameters are automatically forwarded to the ros to perform an earthquake simulation which is based on a spectral element method sem a new island wide high resolution sem mesh model is developed for the whole taiwan in this study we have improved sem mesh quality by introducing a thin high resolution mesh layer near the surface to accommodate steep and rapidly varying topography the mesh for the shallow sedimentary basin is adjusted to reflect its complex geometry and sharp lateral velocity contrasts the grid resolution at the surface is about 545 m which is sufficient to resolve topography and tomography data for simulations accurate up to 1 0 hz the ros is also an infrastructural service making online earthquake simulation feasible users can conduct their own earthquake simulation by providing a set of source parameters through the ros webpage for visualization a shakemovie and shakemap are produced during the simulation the time needed for one event is roughly 3 min for a 70 s ground motion simulation the ros is operated online at the institute of earth sciences academia sinica http ros earth sinica edu tw our long term goal for the ros system is to contribute to public earth science outreach and to realize seismic ground motion prediction in real time

ground motion observations at hotel montana during the m 7 0 2010 haiti earthquake topography or soil amplification unusually severe structural damage was reported during the 2010 m 7 0 haiti earthquake in the vicinity of hotel montana located on top of a ridge in the district of petionville prompted by the observations u s geological survey seismic stations were deployed and aftershock recordings indicated ground motion amplification on the top of the hill compared to adjacent stations on reference site conditions the presence of topographic relief has been shown to significantly aggravate the consequences of strong ground motion during past events and topographic effects were brought forward to explain the observations in this paper we test the hypothesis of topographic amplification as the dominant factor that contributed to the damage concentration in the vicinity of hotel montana we initially conduct numerical simulations of the ridge seismic response assuming elastic homogeneous site conditions and show that numerical predictions of topographic amplification disagree with the field data both in amplitude and in frequency conversely while 1d ground response analyses for the site conditions at the hilltop predict amplification in the same frequency range as the field data they significantly underestimate the recorded amplitude we then conduct numerical simulations of the foothill ridge response to seismic motion while accounting for soil layering and qualitatively demonstrate that the recorded amplification is most likely attributed to coupled site topographic amplification effects namely to seismic waves trapped in the soft soil layers of the near surface amplified as a consequence of reverberations and further modified due to diffraction and scattering upon incidence on the irregular ground surface parametric investigations of the topography soil amplification coupling effects are then conducted and our results show that when accounting for a hypothetical soil bedrock interface at 100 m depth predictions are in excellent agreement with the observed motion

topographic site effects a comparison of two nonreference methods abstract we present an experimental study of topographic site effects the data we use come from an experiment carried out during the summer of 1989 in epire northern greece ten digital stations recorded a total of 68 small earthquakes a recent article chavez garcia et al 1996 presented a comparison between site effects determined using horizontal to vertical spectral ratios hvsr for this data set and theoretical modeling in this note we compare the topographic site effects determined using hvsr with another independent experimental estimate a generalized inversion scheme gis neither hvsr nor gis depend on the availability of a reference site we obtain a very good agreement between both estimates of topographic site effects for both horizontal components our results support the use of hvsr to determine topographic site effects

3d numerical modelling for interpreting topographic effects in rocky hills for seismic microzonation the case study of arquata del tronto hamlet abstract the 2016 2017 seismic sequence in the central apennines italy demonstrated once again the relevant role of the differentiated seismic effects related to different features in complex geological contexts at a short distance i e soft sediment filled valley hilly relieves complex buried geometries the heavy damages of old settlements located on the top of a rocky hill such as arquata del tronto hill raised the question on the main role of three dimensional movements of asymmetrical isolated rocky reliefs in generating disruptions during the seismic shaking in order to shed light on these effects the writing authors analysed the seismic response of a digital 3d model of the arquata del tronto hill that was constructed by considering the topography and the underground geological settings of the area the seismic response was evaluated through 3d numerical simulations of seismic waves propagation with the spectral element method for the period range 0 1 1 s that covers the typical resonance frequencies of the buildings involved in the studied case the obtained results explain the recorded strong motion at arquata site and are consistent with the observed heterogeneous damage distribution this study evidences the need for accurate 3d models in the evaluation of the seismic response of ridges with topographic and geological asymmetries and demonstrates that the common usage of 2d simplified simulations to approximate the 3d seismic behaviour is not correct additionally the study points out the paramount role that the characterization in engineering geological terms plays in the numerical 3d simulation of the seismic site response thus in microzoning studies simplifications related to both dimensional and geo litho seismic characterizations should be avoided

effects of realistic surface topography on seismic ground motion in the yangminshan region of taiwan based upon the spectral element method and lidar dtm we combine light detection and ranging lidar digital terrain model dtm data and an improved mesh implementation to investigate the effects of high resolution surface topography on seismic ground motion based upon the spectral element method in general topography increases the amplitude of shaking at mountain tops and ridges whereas valleys usually have reduced ground motion as has been observed in both records from past earthquakes and numerical simulations however the effects of realistic topography on ground motion have not often been clearly characterized in numerical simulations especially the seismic response of the true ground surface here we use lidar dtm data which provide two meter reso lution at the free surface and a spectral element method to simulate three dimensional 3d seismic wave propagation in the yangminshan region in taiwan incorporating the effects of realistic topography a smoothed topographic map is employed beneath the model surface in order to decrease mesh distortions due to steep ground surfaces numerical simulations show that seismic shaking in mountainous areas is strongly affected by topography and source frequency content the amplification of ground motion mainly occurs at the tops of hills and ridges whilst the valleys and flat topped hills experience lower levels of ground shaking interaction between small scale to pographic features and high frequency surface waves can produce unusually strong shaking we demonstrate that topographic variations can change peak ground accel eration pga values by 50 in mountainous areas and the relative change in pga between a valley and a ridge can be as high as a factor of 2 compared to a flat surface response this suggests that high resolution realistic topographic features should be taken into account in seismic hazard analysis especially for densely populated moun tainous areas

seismic performance of loess mudstone slope in tianshui centrifuge model tests and numerical analysis abstract dynamic behavior and failure mechanism of slope during earthquake are hot topics in geotechnical engineering community in tianshui area northwest of china the deformation features of loess mudstone slopes induced by earthquakes are still not well understood the current study aims to discuss the dynamic behavior of the slope under earthquake by performing a series of centrifuge shaking table tests and numerical simulations the results are processed for pga amplificatory effect study and to evaluate the earthquake induced deformation mechanism better agreement is obtained between the results of numerical simulations and centrifuge tests the results indicated that the acceleration response of the loess mudstone slope showed several amplifying characteristic the height effect lithologic effect and surface effect it also proves that the displacements in the loess layer are much larger than mudstone as the input amplitude increased the shear plastic zone developed along a further slide surface tension plastic zone mainly occurred at the crest roughly the regions of earthquake induced deformation state increased with the increase in amplitude of earthquake wave deformations occurred at the upper part of the slope tensile cracks evolved on the crest and the upper part of slope in loess layer moreover failures occurred at slope surface and only slight deformation at slope toe deformations with continuous shear cracks and slope surface upheavals developed at the middle part of slope

topographic site effects and hvsr a comparison between observations and theory we present a comparison between observed and predicted amplification on a topographic feature our data come from an ad hoc experiment carried out during the summer of 1989 in epire northern greece ten digital autonomous three component stations recorded a total of 68 small earthquakes as these data were inadequate to compute empirical transfer functions using the standard spectral ratio ssr technique we explored the possible use of horizontal to vertical spectral ratios hvsr first we compare hvsr computed from theoretical transfer functions for incident p sv and rayleigh waves with the horizontal transfer function for each incidence type second we compute hvsr for our weak motion data set and show that the results are stable with a scatter not larger than that usually accepted in ssr studies we observe significant differences between n s and e w motion when we compare hvsr with theoretical transfer functions we obtain a better agreement for sv motion than for sh motion amplification levels are similar between hvsr and predicted amplification even for the sh case this suggests that discrepancies that have been signaled for the topographic amplification between observations and predictions could be due to site effects being present in the reference station used to computed ssr our results support the use of hvsr to determine topographic site effects thus hvsr may have a large potential to evaluate site effects in a wider variety of geological conditions than previously thought without the shortcomings of ssr finally we show that hvsr computed from noise recordings gives a reasonable estimate of hvsr computed from weak motion data although this conclusion should be better substantiated our preliminary results are encouraging

nature and degree of aqueous alteration in cm and ci carbonaceous chondrites we investigated the petrologic geochemical and spectral parameters that relate to the type and degree of aqueous alteration in nine cm chondrites and one ci ivuna carbonaceous chondrite our underlying hypothesis is that the position and shape of the 3 m band is diagnostic of phyllosilicate mineralogy we measured reflectance spectra of the chondrites under dry conditions elevated temperatures and vacuum 10 8 to 10 7 torr to minimize adsorbed water and mimic the space environment for subsequent comparison with reflectance spectra of asteroids we have identified three spectral cm groups in addition to ivuna group 1 the least altered group as determined from various alteration indices is characterized by 3 m band centers at longer wavelengths and is consistent with cronstedtite fe serpentine group 3 the most altered group is characterized by 3 m band centers at shorter wavelengths and is consistent with antigorite serpentine group 2 is an intermediate group between group 1 and 3 ivuna exhibits a unique spectrum that is distinct from the cm meteorites and is consistent with lizardite and chrysotile serpentine the petrologic and geochemical parameters which were determined using electron microprobe analyses and microscopic observations are found to be consistent with the three spectral groups these results indicate that the distinct parent body aqueous alteration environments experienced by these carbonaceous chondrites can be distinguished using reflectance spectroscopy high quality ground based telescopic observations of main belt asteroids can be expected to reveal not just whether an asteroid is hydrated but also details of the alteration state

parametric investigation on the effect of near surface soil properties on the topographic amplification of ground motions abstract this study investigates the effect of near surface soil properties on the topographic amplification of ground motions based on the seismic response analysis of a 2d slope model with horizontally stratified soil medium finite difference simulations are performed to calculate the nonlinear elastoplastic response of the slope model using strong motion records as excitation then a series of parametric analyses are carried out to quantitatively evaluate the influence of several factors such as the shear wave velocities of the superficial layers thickness of the surface layer and soil material of the surface layer the numerical results indicate that the decrease in the average shear wave velocity of superficial layers would enhance the topographic effect in the area close to slope crest in order to further assess the influence of different superficial soil profiles seismic response analysis is conducted for a group of 2d slope models which are built based on borehole data the regression analysis of simulation results further confirms that the intensity of topographic effect gradually increases with decreasing vs30 finally the results of numerical analyses are compared with current seismic code provisions

ground motion amplitude across ridges abstract local amplification and wave diffraction on an elongated ridge near sourpi in central greece were studied by the analysis of seismic records of local and regional earthquakes data were obtained during field work especially designed for this purpose these data were analyzed in the frequency and time domains in the frequency domain spectral ratios show amplifications of 1 5 to 3 at the ridge top relative to the base of the ridge the horizontal components of motion are more amplified than the vertical component and the observed spectral ratios seem stable for different earthquake locations theoretical spectral ratios calculated by the indirect boundary element method are dependent on earthquake location but are in general agreement with the observed spectral ratios another dataset from mont st eynard in the french alps showed similar characteristics with spectral amplitudes on the top of the ridge up to four times those on the flank these relative amplifications are within the range predicted by numerical simulations the numerical simulations also show that the topographic effect involves the emission of diffracted waves propagating from the top toward the base of the ridge the use of a seven station array on the ridge at sourpi made it possible to identify such waves the analysis was performed with wave separation methods using singular value decomposition and spectral matrix filtering our results show agreement between experimental data and theoretical results supporting the use of numerical simulations for estimation of purely topography induced amplification on ridge tops our results also show that such amplification is moderate for the ridges under study

unit stream power equation for gravel the basic assumptions used in the derivation of bedload or gravel transport equations are reviewed and examined to determine their validities laboratory data indicate that unit stream power is mor

a proposal for the kinematic modelling of w dipping subductions possible applications to the tyrrhenian apennines system in w dipping subduction zones there is a general eastward progression of the back arc basin accretionary wedge foredeep complex with the forward progression early stages of the complex are revealed by slices of upper crust and sedimentary cover abandoned to the west left floating above a new section of mantle a major shear zone should form at the new moho separating upper crust slices of earlier accretionary stages and the eastward flowing mantle the mantle wedging at the top of the subduction plane could be responsible for the uplift of the central parts of the belt the retreating of the subduction hinge is interpreted as due to the push generated by the eastward mantle flow detected in the hot spot reference frame the foredeep depth is mainly a function of the radius of curvature of the subduction hinge the frontal wedge is constructed from the stacking of the upper layers of the subducting plate and the syntectonic clastics that fill the foredeep which are progressively involved in thrusting and later by extension in order to preserve volume balance the lithosphere of the eastern plate before subduction has to be the same size as that which has been subducted due to the longer length of the arc with respect to the original length of the linear margin between the two converging plates laterally stretched subducted lithosphere is predicted at depth w dipping subductions usually have a short life probably due to their inherent capability to produce new lateral heterogeneities of the lithosphere the thin back arc which are a key factor in controlling and generating new subductions both e and w dipping this model is applied to the apennines tyrrhenian sea system

absorption bands near three micrometers in diffuse reflectance spectra of carbonaceous chondrites comparison with asteroids abstract we measured infrared diffuse reflectance spectra of several carbonaceous chondrites in order to obtain additional information on the surface materials of their presumed parent bodies c type asteroids the presence and intensity of absorption bands near 3 m in the reflectance spectra are due to the presence and abundance of hydrates and or hydroxyl ions the absorption features of the 3 m hydration bands of carbonaceous chondrites were compared with those of asteroids 1 ceres and 2 pallas they are commonly classified into separate subtypes g and b type the spectral shapes of pallas and renazzo cr2 chondrite around the 3 m absorption band are an excellent match this result may suggest that the amount of hydrous minerals in the surface material of pallas is smaller than that in the cm2 or ci chondrites and the hydrous minerals on the surface of pallas may be similar to those found in renazzo the spectral features around the 3 m band of ceres are different from those of carbonaceous chondrites studied in this paper

infrared imaging spectroscopy with micron resolution of sutter s mill meteorite grains synchrotron based fourier transform infrared spectroscopy and raman spectroscopy are applied with submicrometer spatial resolution to multiple grains of sutter s mill meteorite a regolith breccia with cm1 and cm2 lithologies the raman and infrared active functional groups reveal the nature and distribution of organic and mineral components and confirm that sm12 reached higher metamorphism temperatures than sm2 the spatial distributions of carbonates and organic matter are negatively correlated the spatial distributions of aliphatic organic matter and oh relative to the distributions of silicates in sm2 differ from those in sm12 supporting a hypothesis that the parent body of sutter s mill is a combination of multiple bodies with different origins the high aliphatic ch2 ch3 ratios determined from band intensities for sm2 and sm12 grains are similar to those of idps and less altered carbonaceous chondrites and they are significantly higher than those in other cm chondrites and diffuse ism objects

the schmidt hammer in rock material characterization the schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material however a number of issues such as hammer type normalization of rebound values specimen dimensions surface smoothness weathering and moisture content and testing data reduction and analysis procedures continue to influence the consistency and reliability of the schmidt hammer test results this paper presents a a critical review of these basic issues and b the results of tests conducted on granitic rocks of various weathering grades in the light of the conclusions of this review it was found that a very good correlation exists between l and n hammer rebound values and that both hammers are fairly sensitive to the physical properties particularly to dry density though less so to effective and total porosities the n hammer producing a lesser scatter in the data proved to be more efficient than the l hammer in predicting uniaxial compressive strength and young s modulus the exponential form of the correlation curves was found to reflect microstructural changes during the course of weathering and the differences in the probing scales or mechanisms in the means of measuring these mechanical properties and could be generalized to other crystalline igneous rocks the possibility of predicting weathering grades from rebound values was also explored the changes in the rebound values during multiple impacts at a given point produced a better indication of the weathering grade than a single impact value it was concluded that increasing the impact energy and plunger tip diameter should significantly reduce the scatter in coarse grained weathered rocks and hence improve the reliability of the schmidt hammer as a rock material characterization tool

phyllosilicate rich chondrule rims in the vigarano cv3 chondrite evidence for parent body processes abstract a petrographic and scanning electron microscopic study of the vigarano cv3 carbonaceous chondrite reveals that a small proportion 5 of the fine grained rims surrounding chondrules consist mainly of phyllosilicates saponite and serpentine and minor but variable amounts of ferrihydrite most of the rims consist mainly of fe rich olivine the phyllosilicate rich rims and the chondrules that they enclose show abundant evidence of aqueous alteration low ca pyroxene and olivine at chondrule margins have been partially replaced by phyllosilicate rich materials producing embayments on chondrule surfaces fe ni metal fe sulfide and magnetite in the chondrules have also been partially replaced by fe hydroxide due to preferential replacement of low ca pyroxene and olivine sulfide magnetite and fe hydroxide remain exposed at chondrule margins we discovered a clast 0 7 0 9 mm in size containing several chondrules embedded in a phyllosilicate rich matrix that is almost identical in mineralogy texture and composition to the rims we also found numerous small clasts 20 400 m in size consisting of a similar phyllosilicate rich material in the host vigarano meteorite many of the clasts include fragments of chondrules amoeboid olivine aggregates and ca al rich inclusions these clasts also show abundant evidence of aqueous alteration which is similar to that observed in the rims and their host chondrules from these observations we conclude that the chondrule rim assemblages and the clasts are a part of the same precursor chondrite which was fragmented during brecciation on the meteorite parent body we interpret that a portion or portions of the vigarano parent body was aqueously altered and the interchondrule matrix was largely converted to phyllosilicates and ferrihydrite this hydrated portion was later fragmented and brecciated by impacts as fragmentation occurred preferentially along the phyllosilicate rich porous matrix most of the ejected clasts consisted of a chondrule rimmed by remnant matrix the clasts were rounded by abrasion during brecciation and transportation and finally mixed into an anhydrous portion in the regolith from which the vigarano meteorite was derived some of the phyllosilicate rich rims show evidence for partial dehydration during heating before final incorporation into the regolith these results taken together suggest that the vigarano parent body was spatially heterogeneous in degree of aqueous alteration and thermal metamorphism and the host vigarano meteorite is a breccia consisting of numerous clasts from many different locations

frequency scaled curvature as a proxy for topographic site effect amplification and ground motion variability we introduce a new methodology to predict the topographic site effect amplification ground motions obtained from a large database of 3d earthquake simulations show that the curvature of the earth s surface defined as the second spatial derivative of the elevation map is correlated with the topographic site amplification the highest correlation between the frequency dependent topographic amplification and the topographic curvature is reached when the curvature is smoothed over a characteristic length equal to the s wavelength divided by two i e frequency scaled curvature fsc this implies the amplification is caused by topographic features for which horizontal dimensions are similar to half of the s wavelength the largest ground motion variabilities are found at sites located on slopes and on the largest summits whereas intermediate variabilities occur over narrow ridges and a stable behavior in the bottom valleys the fsc proxy allows the identification of topographic features with similar characteristic dimensions and probabilistic estimates of amplification values accounting on the variability of ground motions due to source site interactions amplification estimates using the fsc proxy are robust and easily computed from digital elevation maps provided that reasonable values of s wave velocities are available in the area of interest

aqueous alteration and brecciation in bells an unusual saponite bearing cm chondrite the petrological and mineralogical characteristics of the unusual cm2 chondrite bells have been investigated in detail by scanning electron microscopy sem electron microprobe analysis epma and transmission electron microscopy tem bells is a highly brecciated chondrite which contains few intact chondrules a very low abundance of refractory inclusions and is notable in having an unusually high abundance of magnetite which is disseminated throughout the fine grained matrix fragmental olivines and pyroxenes are common and based on compositional data appear to have been derived from chondrules as a result of extensive brecciation the fine grained mineralogy of matrix in bells differs considerably from other cm chondrites and has closer affinities to matrix in ci chondrites the dominant phases are fine grained saponite interlayered with serpentine and phases such as tochilinite and cronstedtite which are typical of cm chondrite matrices are entirely absent pentlandite pyrrhotite magnetite anhydrite calcite and rare ti oxides also occur as accessory phases based on its oxygen and noble gas isotopic compositions zadnik 1985 rowe et al 1994 bells can be considered to be a cm2 chondrite although its bulk composition shows some departures from the typical range exhibited by this group however these variations in bulk chemistry are entirely consistent with the observed mineralogy of bells the unusual fine grained mineralogy of bells matrix can be reasonably attributed to the combined effects of aqueous alteration and advanced brecciation in a parent body environment extensive brecciation has assisted aqueous alteration by reducing chondrules and mineral grains into progressively smaller grains with high surface areas which are more susceptible to dissolution reactions involving aqueous fluids this has resulted in the preferential dissolution of fe rich chondrule olivines which are now completely absent in bells although present in other cm chondrites the formation of saponite in bells probably resulted from the dissolution of relatively silica rich phases such as pyroxene and olivine that were derived from chondrules the result of such dissolution reactions would be to increase the activity of silica in the fluid phase at least on a localized scale stabilizing saponite in preference to serpentine an increase in asio2 would also have destabilized preexisting cronstedtite which may have reacted to form magnetite and mg fe serpentine under conditions of constant o2

evaluation of complex site effects through experimental methods and numerical modelling the case history of arquata del tronto central italy abstract this work deals with the experimental and numerical evaluation of the local seismic response of arquata del tronto area marche region central italy severely struck by the mw 6 0 august 24th 2016 earthquake arquata main village rises on elongated wnw ese trending ridge of the central apennines thrust belt central italy at elevations about 170 m higher than the underlying alluvial valleys where borgo and san francesco hamlets are built on despite their proximity less than 500 m arquata del tronto borgo and san francesco reported a different damage distribution after the august 2016 mainshock suggesting that the seismic response of the area may be controlled by site effects in order to explore this hypothesis we evaluated the 2d numerical local seismic response along four representative geological cross sections passing through arquata del tronto san francesco and borgo additional 1d analyses were carried out at strategic points along the cross sections in order to explore the 2d physical phenomena governing the local response the satisfactory agreement between numerical amplification functions in linear range and experimental amplification functions obtained by the generalized inversion technique git applied to a large number of aftershocks confirms the substantial reliability of the subsoil models numerical analyses representative of the 2016 mainshock were carried out and processed in terms of peak and key ground motion parameters a comparison with the damage induced by the 2016 mainshock was finally undertaken substantially justifying the observed pattern this study provides general implications about site response and seismic microzonation in sites characterized by similar complex geological and morphological settings

investigating fault reactivation during multiple tectonic inversions through mechanical and numerical modeling an application to the central northern apennines of italy abstract within inversion tectonic contexts the reactivation of pre existing discontinuities depends upon many structural stratigraphic and mechanical factors among these a fundamental aspect is represented by the orientation and attitude of pre existing discontinuities with respect to the new stress field the aim of this work is to evaluate the stress regimes and the mechanical conditions that controlled the reactivation of segmented pre thrusting normal faults in the central northern apennines of italy these faults were involved both in positive and negative inversion tectonic events during tertiary quaternary times mechanical slip tendency analysis and numerical using coulomb 3 3 software models allowed us to reconstruct a 3d stress field for both inversion events and to evaluate the effect of many parameters orientation of faults fault dip angle and mechanical parameters on fault reactivation our results highlighted that the orientation of pre existing faults with respect to the stress axes represents the main factor controlling inversion tectonic phenomena where other mechanical and geometric variables exert a subordinate role the models well reproduce the neogene quaternary deformation history reconstructed from detailed geological and structural analyses for the central northern apennines of italy and could be applied to other regions that have experienced inversion tectonic processes

formation history of ci like phyllosilicate rich clasts in the tsukuba meteorite inferred from mineralogy and noble gas signatures abstract fine grained angular black clasts with longest dimensions up to 800 m were found dispersed in a brecciated region in the tsukuba meteorite the clasts much darker than the dark portions of the light dark structure in the tsukuba host are characterized by the presence of plaquette spherulitic and framboidal magnetites and pseudo hexagonal pyrrhotite synchrotron radiation x ray diffraction analyses showed that the major silicate phases in the clasts are saponite and serpentine transmission electron microscopy tem revealed that the phyllosilicates have compositions quite similar to those in the orgueil ci carbonaceous chondrite therefore mineralogically and chemically the clasts resemble ci chondrites and are quite different from the host h5 6 chondrite tsukuba the clasts serve as an indicator of temperatures during regolith lithification of the tsukuba parent body because their mineralogy and noble gas compositions are subject to change during weak heating the 001 basal spacing of saponite in the clast is 13 2 a which indicates that saponite retains interlayer water molecules this observation and the presence of serpentine suggest that the clasts as a whole have never been heated above 500 c noble gas analyses showed that the clasts contain large amounts of solar and primordial noble gases the results of stepwise heating analyses indicate that no apparent thermal loss of noble gases from the clasts occurred consistent with the mineralogical evidence tem observation revealed that the periphery of a clast was transformed into amorphous phases indicating that only the periphery was heated to 700 c based on the results of our analyses the formation history of the clasts can be evaluated as follows constituents of the clasts had been exposed to solar wind on the surface of the ci chondrite like parent body and formed the clasts after ejection from the ci like parent body the ci like meteoroid accreted to the tsukuba parent body after early thermal metamorphism that reached 700 1000 c the clasts must have been located in the regolith because they were found among the light dark structure in the meteorite and contain abundant solar noble gases impacts into the regolith have crushed the clasts into smaller pieces and probably induced lithification of the regolith material during lithification the peripheries of the clasts were heated briefly to 700 c but the temperature of the interior of the clasts has never exceeded 500 c this is the first evidence constraining temperature during lithification of the ordinary chondrite parent body regolith finally the tsukuba meteoroid including the ci like clasts was ejected from the tsukuba parent body and fell onto the earth after a transit time of 8 1 ma

the interaction of seismic waves with step like slopes and its influence on landslide movements abstract the interaction of seismic waves with slopes is a major factor influencing landslide movements that involve slope stability local site seismic amplification and topographic effects affecting ground motion the results of a numerical study of landslide movements induced by the interaction of seismic waves with step like slopes are presented here to investigate this input slope interaction a dynamic analysis was performed using the finite difference stress strain numerical code flac 6 0 under visco plastic conditions the dynamic signals were selected to be representative of different peak ground accelerations pgas arias intensities and frequency contents and they were used in a parametric study of different step like slopes with different geometrical configurations in terms of dip height and thickness of geological strata the derived outputs were processed for a seismic amplification analysis and to evaluate the induced stress strain effects in terms of progressive failure and resulting displacements the obtained results i describe a fundamental role of topography in amplifying or de amplifying the seismic ground motion ii demonstrate that the progressive failure of unsheared slopes influences the seismic amplification iii show that the strain effects on unsheared slopes in terms of progressive failure are more intense with increasing arias intensity and slope dip iv prove that amplification or de amplification processes can justify the values of displacements involving pre existing landslide masses which are significantly different with respect to those expected on the basis of sliding block approaches i e newmark s and flexible sliding block methods v highlight that in the geological setting considered here the seismically induced displacements arising from the reactivation of pre existing landslide masses can be significantly underestimated by sliding block approaches in the case of low angle slopes characterised by high k values i e the ratios between the critical pseudostatic threshold ky of the landslide and pgas of the applied seismic input

investigating the effect of earthquakes on open pit mine slopes abstract this paper develops a database for studying the circumstances under which dynamic loading of earthquake can cause slope failure in deep open pit mines with a long lifetime the database includes 177 open pit mines hit by earthquake and 95 natural slopes and 37 tailing dams which have been failed by earthquakes both earthquake parameters and geomechanical characteristics involved in each case study are investigated from this information the elements playing role in the earthquake triggered failures in natural slopes and tailing dams are identified and used to indicate conditions that may result in earthquake induced failures in open pit mines the result shows that even though the valley shape geometry and absence of the top weathered layer make open pit mines less prone to earthquake induced failures excessive pore pressure in pit slopes still carries the risk of earthquake triggered failures in open pit slopes only limited numbers of open pit mines have been so far exposed to earthquakes with the same parameters as those causing failure in natural slopes and tailing dams that is the response of open pit mines to higher magnitude shallower and closer earthquakes is still unknown studying the earthquakes that have caused failure in other slopes it is concluded that open pit mines may still experience reportable failures if struck by earthquakes with local depth of less than 40 km epicentral distance of less than 100 km and magnitude of greater than 6 0 the necessity of accounting for seismic loading in slope stability analyses and active dewatering for open pit mines located in seismically active areas are also discussed

ground motions at the outermost limits of seismically triggered landslides abstract over the last few decades we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes 1987 whittier narrows california m 5 9 1987 superstition hills california m 6 5 1994 northridge california m 6 7 and 2011 mineral virginia m 5 8 in an additional two earthquakes 1976 guatemala m 7 5 and 1983 coalinga california m 6 5 we determined limits using high resolution aerial photographic interpretation in conjunction with more limited ground investigation limits in these earthquakes were defined by the locations of the very smallest failures 3 from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking because we and our colleagues conducted all of these investigations consistent methodology and criteria were used in determining limits in the six earthquakes examined we correlated the outermost landslide limits with peak ground accelerations pgas from shakemap models of each earthquake for the four earthquakes studied by field investigation the minimum pga values associated with farthest landslide limits ranged from 0 02 g to 0 08 g the range for the two earthquakes investigated using aerial photographic interpretations was 0 05 0 11 g although pga values at landslide limits depend on several factors including material strength topographic amplification and hydrologic conditions these values provide an empirically useful lower limiting range of pga needed to trigger the smallest failures on very susceptible slopes in a well recorded earthquake this pga range can be used to identify an outer boundary within which we might expect to find landsliding in earthquakes that are not well recorded mapping the outermost landslide limits provides a useful clue about ground motion levels at the mapped limits

pre existing cross structures and active fault segmentation in the northern central apennines italy abstract the multideformed axial zone of the apennines provides a great opportunity to explore the influence of pre existing cross structures inherited from pre quaternary tectonic phases on the segmentation of quaternary active seismogenic extensional faults detailed geological and structural data and their comparison with seismological data show that although the attitudes strike and dip of oblique pre existing faults are certainly an important factor in determining a segment boundary the size of the inherited oblique structures seems to be more crucial pre existing cross structures with lengths ranging from several kilometers to a few tens of kilometers show a twofold behavior they can act as segment barriers during the rupture of a single fault segment or they can be reactivated as transfer zones inducing the activation of two adjacent segments that belong to the same fault system regional basement crustal oblique pre existing cross structures with lengths ranging from several tens of kilometers to hundreds of kilometers commonly nne striking may act as persistent structural barriers that halt both fault segment and fault system propagation thus determining their terminations and maximum sizes in the northern central apennines the nne striking ancona anzio valnerina and ortona roccamonfina tectonic lineaments although having been repeatedly reactivated since the mesozoic represent the most important examples of these structures moreover probably due to their misorientation with respect to the present extensional stress field regional nne striking pre existing structures appear to be less likely to produce strong magnitude events no surface evidence for quaternary faulting has been found thus far and historical and instrumental seismicity shows only m m 7 event on the other hand is more likely to occur along the n nw s se trending normal fault systems lastly we propose a model that can explain the different sizes of fault segments and fault systems on the basis of their location with respect to the persistent structural barriers and their spacing in this view our results may contribute to a more reasonable assessment of the nature and size of future surface ruptures in the northern central apennines which are of critical importance to estimating seismic hazard

relationship between positive cerium anomaly and adsorbed water in antarctic lunar meteorites abstract concentrations of adsorbed water in single mineral grains of antarctic lunar meteorites were determined with micro infrared ir spectroscopy a relationship was found between the mineral s ability to adsorb water and the extent of ce anomaly in rare earth element ree patterns precisely determined by the isotope dilution method using a thermal ionization mass spectrometer asuka a 881757 a lunar meteorite from the mare basalt without ce anomaly showed no trace of ir absorption due to adsorbed water on the contrary yamato y 791197 109 y 86032 98 y 86032 95 y 791197 115 and y 82192 55a from the lunar highland exhibiting positive ce anomaly showed ir absorption due to adsorbed water in some of their minerals the detected water would be of terrestrial origin because it was not structurally bound and easy to exchange judging from the spectral band shape the contrast in concentration of adsorbed water between the lunar highland and the mare basalt is derived from a difference in the density of microfractures in mineral grains average concentrations of adsorbed water in the lunar highland meteorites were 3 8 mg cm3 for pyroxene and olivine and 1 7 mg cm3 for plagioclase this contrast between minerals is noteworthy because it has been known that ce anomaly of pyroxene and olivine is larger than that of plagioclase both for antarctic lunar meteorites and some lunar rocks furthermore more adsorbed water was detected for minerals in meteorites that exhibit larger ce anomaly the present observations demonstrate that the extent of ce anomaly correlated with the concentration of adsorbed water which suggests that active mineral surface resulting in adsorption of water could be a trace of interaction forming ce anomaly terrestrial weathering on antarctica and ree fractionation on the moon are discussed for possible origins of the ce anomaly

a new metal rich chondrite grouplet abstract a new grouplet of primitive metal rich chondrites here called the cb c carbonaceous b bencubbinite chondrites has been recognized it includes bencubbin weatherford hammadah a1 hamra hh 237 and queen alexandra range que 94411 paired with que 94627 their mineral compositions as well as their oxygen and nitrogen isotopic compositions indicate that they are closely related to the cr and ch chondrites all of which are members of the more inclusive cr clan cb chondrites have much greater metal silicate ratios than any other chondrite group widely increasing the range of metal silicate fractionation recorded in solar nebular processes they also have the greatest moderately volatile lithophile element depletions of any chondritic materials metal has compositional trends and zoning patterns that suggest a primitive condensation origin in contrast with metal from other chondrite groups cb chondrites as well as other cr clan chondrites have much heavier nitrogen higher 15n 14n than that in other chondrite groups the primitive characteristics of the cb chondrites suggest that they contain one of the best records of early nebular processes another chondrite grosvenor mountains 9555 1 is petrographically similar to the cb chondrites but its mineral and oxygen and nitrogen isotope compositions indicate that it formed from a different nebular reservoir

seismic response of the lengzhuguan slope caused by topographic and geological effects abstract earthquake induced slope failure often results in a large loss of life and property and thus understanding how a slope responds to seismic shaking can reveal the mechanism and movement of this kind of phenomenon after the 2008 wenchuan earthquake a dense array of strong earthquake seismographs were deployed along the lengzhuguan slope luding county sichuan province southwest china to study the seismic response of the slope three main shocks were recorded in 2014 and 2015 with epicenter distances between 34 km and 70 km observation data show that the ground motion was polarized in the direction perpendicular to the elongation direction of the ridge near 50 azimuth from north with an amplification coefficient 10 and a ground motion amplification frequency band between 1 5 and 2 5 hz the results of a series of numerical simulation experiments conducted using the finite difference method indicate that the observed seismic response characteristics of the lengzhuguan slope can be reproduced only by a heterogeneous model containing a loose deposit layer with a thickness of 30 m it was found that geological and topographic conditions resulted in complex slope seismic response characteristics that were coupled in both time and frequency and the geological conditions dominated the seismic response of the slope in terms of co seismic landslide hazard more attention should be given to subsurface lithology and rock mass structure

interactions between mantle upwelling drainage evolution and active normal faulting an example from the central apennines italy summary in this paper we show that the processes that have shaped the quaternary surface development of the apennines in central italy are all consequences of a single subcrustal process the upwelling of the mantle the relationship between gravity and topography shows that mantle convection is responsible for a long wavelength 150 200 km topographic bulge over the central apennines and stratigraphic evidence suggests this bulge developed in the quaternary active normal faulting is localized at the crest of this bulge and produces internally draining fault bounded basins these basins have been progressively captured by the aggressive headward erosion of major streams that cut down to the sea on the flanks of the regional bulge the only surviving closed basins are those on the apennine watershed most distant from the marine base level where continued normal faulting is still able to provide local subsidence that defeats their capture by the regional drainage network understanding the competition between regional capture and local fault related subsidence of intermontane basins is crucial for recognizing potentially hazardous active faults in the landscape and also for interpreting the sediment supply to adjacent offshore regions central italy provides a good modern analogue for processes that are probably common in the geological record particularly on rifted margins and intracontinental rifts but may not have been fully appreciated

characterization of carbonaceous matter in xenolithic clasts from the sharps h3 4 meteorite constraints on the origin and thermal processing abstract primitive xenolithic clasts often referred to as dark clasts are well known in many regolith breccias the sharps h3 4 ordinary chondrite contains unusually large dark clasts up to 1 cm across poorly graphitized carbon pgc with fe ni metal and described as carbon rich aggregates has been reported in these clasts brearley 1990 we report detailed analyses of carbonaceous matter in several identical sharps clasts using ftir raman c xanes and tem that provide insight on the extent of thermal processing and possible origin of such clasts we also prepared acid residues of the clasts using the hcl hf method and conducted mass spectrometric analysis of the entrained noble gases carbonaceous matter is often used to infer thermal history due to its sensitivity to thermal processes the ftir spectra of the acid residue from the sharps clast suggest that carbonaceous matter in the clast contains less hydrogen and oxygen compared to acid residues from typical type 3 4 ordinary chondrites the metamorphic temperatures obtained by raman spectroscopy ranges between 380 c and 490 c tem observations indicate that the clasts experienced a peak temperature of 300 c to 400 c based on the carbon d002 layer lattice spacing of c rich aggregates these estimates are consistent with an earlier estimate of 330 50 c that is also estimated by the d002 layer lattice spacing brearley 1990 it should be noted that the lattice spacing thermometer is based on terrestrial metamorphose rocks and thus temperature was probably underestimated meanwhile the c xanes spectra of the c rich aggregates show high exciton intensities indicative of graphene structures that developed at around 700 800 c following an extensive period of time millions of years however the surrounding matrix areas experienced lower temperatures of less than 300 500 c noble gas analysis of the acid residue from the sharps clasts shows that the residue is almost identical with some material reported in carbonaceous chondrites i e heavily enriched in the q gas component as well as hl gas from presolar diamonds and ne e h from presolar sic these results indicate that the c rich aggregates in the sharps clasts formed under relatively high temperature conditions up to 800 c and were subsequently mixed with lower temperature matrix probably in a different parent body before they were incorporated into the final sharps lithology by collision

spatial distribution of landslides triggered from the 2007 niigata chuetsu oki japan earthquake abstract understanding the spatial distribution of earthquake induced landslides from specific earthquakes provides an opportunity to recognize what to expect from future events the july 16 2007 mw 6 6 mjma 6 8 niigata chuetsu oki japan earthquake triggered hundreds of landslides in the area surrounding the coastal city of kashiwazaki and provides one such opportunity to evaluate the impacts of an offshore magnitude 6 earthquake on a steep coastal region as part of a larger effort to document all forms of geotechnical damage from this earthquake we performed landslide inventory mapping throughout the epicentral area and analyzed the resulting data for spatial seismic motion and geologic correlations to describe the pattern of landsliding coupled with examination of a third party aerial photo based landslide inventory our analyses reveal several areas of high landslide concentration that are not readily explained by either traditional epicentral and fault plane distance metrics or by recorded and inferred ground motions whereas average landslide concentrations averaged less than 1 landslide per square kilometer ls km2 some areas reached up to 2 ls km2 in the nishiyama hills to the northeast of kashiwazaki and between 2 and 11 ls km2 in coastal areas to the north and south of the city correlation with seismometer based and monument overturning back calculated ground motions suggests that a minimum peak ground acceleration pga of approximately 0 2 g was necessary for landsliding throughout the region but does not explain the subregional areas of high landslide concentration however analysis of topographic slope and the distribution of generally weak dip slope geologic units does sufficiently explain why on a sub regional scale high landslide concentrations occurred where they did these include 1 an inland region of steep dip slope anticlinal sedimentary strata with associated fold belt compression and uplift of the anticline and 2 coastal areas with generally weaker weathered outcrop lithology and steeper slopes resulting from active marine and terrestrial cliff processes the results offer lessons for understanding the effects of earthquakes on both regional and subregional scales with regard to the spatial distribution of landsliding

compilation of alluvial channel data a computer based collection of alluvial channel data from both laboratory and field investigations has been prepared the collection contains 5 263 records of laboratory observations and 1 764 records of field observations each record contains 10 alluvial channel variables presented in a standard format in si international system units the paper presents a discussion of the contents of the data collection a review of some of the data sources and comparisons with earlier data collections information for users of the data collection is also presented

site effect evaluation using spectral ratios with only one station the spectral ratio technique is a common useful way to estimate empirical transfer function to evaluate site effects in regions of moderate to high seismicity the purpose of this paper is to show that it is possible to estimate empirical transfer function using spectral ratios between horizontal and vertical components of motion without a reference station the technique originally proposed by nakamura to analyze rayleigh waves in the microtremor records is presented briefly and it is discussed why it may be applicable to study the intense s wave part in earthquake records results are presented for three different cities in mexico oaxaca oax acapulco gro and mexico city these cities are very different by their geological and tectonic contexts and also by the very different epicentral distances to the main seismogenic zones affecting each city each time we compare the results of nakamura s technique with standard spectral ratios in all three cases the results are very encouraging we conclude that if site effects are caused by simple geology a first estimate of dominant period and local amplification level can be obtained using records of only one station

what is a reference site many methods for estimating site response compare ground motions at sites of interest to a nearby rock site that is considered a reference motion the critical assumption in these methods is that the surface rock site record reference is equivalent to the input motion at the base of the soil layers data collected in this study show that surface rock sites can have a site response of their own which could lead to an underestimation of the seismic hazard when these sites are used as reference sites data were collected from local and regional earthquakes on digital recorders both at the surface and in boreholes at two rock sites and one basin site in the san jacinto mountains southern california the two rock sites keenwild and pinon flat are located on granitic bedrock of the southern california peninsular ranges batholith the basin site garner valley is an ancestral lake bed with watersaturated sediments on top of a section of decomposed granite which overlies the competent bedrock ground motion is recorded simultaneously at the surface and in the bedrock at all three sites when the surface rock sites are used as the reference site i e the surface rock motion is used as the input to the basin the computed amplification underestimates the actual amplification at the basin site for frequencies above 2 to 5 hz this underestimation by a factor of 2 to 4 depending on frequency and site results from the rock sites having a site response of their own above the 2 to 5 hz frequencies the near surface weathering and cracking of the bedrock affects the recorded ground motions at frequencies of engineering interest even at sites that appear to be located on competent crystalline rock the bedrock borehole ground motion can be used as the reference motion but the effect of the downgoing wave field and the resulting destructive interference must be considered this destructive interference may produce pseudo resonances in the spectral amplification estimates if one is careful the bedrock borehole ground motion can be considered a good reference site for seismic hazard analysis even at distances as large as 20 km from the soil site

a case study of site effects on seismic ground motions at xishan park ridge in zigong sichuan china abstract the city of zigong faces severe seismic hazards because of the amplifying effects of its topography and geology to estimate the local site effects an array of 8 accelerographs has been in operation along the xishan park ridge since 2007 in this study site amplifications associated with the ground motion produced by the 2008 wenchuan earthquake is evaluated using the standard spectral ratio ssr technique and root mean square acceleration arms method 2d numerical analysis using finite difference method is then performed and results are compared with monitoring data the results show that topography and local presence of soft materials significantly increase the ground motion in both field observations and the numerical model along the ridge slope the maximum ground motion amplification was obtained at the hilltop for a frequency range 1 10 hz for both ns and ew components significant amplifications occurred at higher frequencies 10 hz and are considered to result from local specific conditions such as rock fracturing and ridge steps thus they do not necessarily occur at the hilltop a slight difference between the two horizontal components ns and ew was observed and this is possibly due to the azimuthal dependence of site effect the computed amplification ratios give amplitudes that are comparable to those indicated by field observations however the calculated spectral amplifications are underestimated at frequencies larger than 3 hz this can be due to the fact that a signal damping ratio used for the whole model does not adequately represent the energy dissipation at high frequency

impact of tensile strength and incident angles on a soil slope under earthquake sv waves abstract the tensile strength and incident angles play important roles in seismically induced slope failures in this paper a new criterion for tension shear coupling is proposed based on several sets of relevant lab data and is verified using the experimental data provided by previous researchers this criterion can perfectly depict the tension region as well as the compression region in the entire stress space moreover the tension shear criterion was converted into an expression that could be directly used in a numerical method and it was verified by a numerical example in addition the sv waves were input using the equivalent nodal force method based on a viscous spring artificial boundary this process was implemented by the abaqus software and two numerical examples were used to verify this method subsequently based on the proposed new criterion and input method the impacts of the strength criterion and incident angles on an analysis of seismically induced slope failures were studied the results indicated that the evaluation of the tension shear region is extremely important in the analysis of the seismically induced slope failures the tensile strength of the seismically induced landslides was overestimated by the calculation of mohr coulomb criterion owing to the ambiguous description of the tensile failure or the tension shear failure the assessment of the slope stability was thus not conservative the incident angles of seismic waves affected the travel path and the directivity of slope seismic responses the sliding displacement of the slope side near the epicenter rose with increasing angles of wave incidence the critical slip surface deepened and the hazard aggravated therefore it is important to introduce both the tensile strength and incident angles when evaluating the stability of slopes subjected to seismic loads

quaternary negative tectonic inversion along the sibillini mts thrust zone the arquata del tronto case history central italy geological and geophysical investigations have been carried out in the surroundings of the villages of pretare and piedilama in the central apennines this area located at the footwall of the prominent nne ssw oriented sibillini thrust front was struck by the august 24th 2016 mw 6 earthquake the results of the geological field survey combined with geological and geophysical subsurface investigations are here illustrated by a detailed geological map and by two significant cross sections the studied area is crossed by the fosso di morricone valley that entrenched within the messinian pelitic arenaceous succession of the laga formation hosts a late pleistocene palaeo landslide the study evidences the occurrence of a n 10 oriented west dipping normal fault here named pretare piedilama fault that controlled the left side of the fosso di morricone valley producing a vertical displacement of the palaeo landslide deposits of about 50 m the geological geomorphological and geophysical data indicate that the fault was active during the late pleistocene and part of the holocene thus constraining a minimum vertical displacement rate of 0 4 mm a in the last 125 ka the geometry of the deformed laga formation cut by the fault suggests to relate it to the late quaternary negative tectonic inversion of a previous thrust plane located in the footwall of the sibillini thrust front the pretare piedilama fault would represent the easternmost tectonic expression of this main potentially active structure future researches could be addressed to detail the age and the actual motion rate of the structure and to define its seismic hazard assessment

modal mineralogy of ci and ci like chondrites by x ray diffraction the ci chondrites are some of the most hydrated meteorites available to study making them ideal samples with which to investigate aqueous processes in the early solar system here we have used position sensitive detector x ray diffraction psd xrd to quantify the abundance of minerals in bulk samples of the ci chondrite falls alais orgueil and ivuna and the antarctic ci like chondrites y 82162 and y 980115 we find that alais orgueil and ivuna are dominated by a mixed serpentine saponite phyllosilicate 81 84 vol plus minor magnetite 6 10 sulphides 4 7 and carbonates 3 this reflects an extended period of aqueous alteration and the near complete transformation of anhydrous phases into a secondary mineral assemblage the similarity in total abundance of phyllosilicate suggests that the ci chondrites all experienced the same degree of aqueous alteration on the parent body in contrast y 82162 contains a highly disordered serpentine saponite phyllosilicate 68 vol sulphide 19 olivine 11 and magnetite 2 this mineralogy is distinct from that of the ci chondrites attesting to both a different starting mineralogy and alteration history the structure and relatively low abundance of the phyllosilicate and the high abundance of olivine are consistent with previous observations that y 82162 represents ci like material that following aqueous alteration suffered thermal metamorphism at temperatures 500 c similarly y 980115 contains disordered serpentine saponite 71 vol sulphide 19 olivine 8 and magnetite 2 confirming that it too is a thermally metamorphosed ci like chondrite we suggest that the ci like chondrites are derived from a different parent body than the ci chondrites which underwent short lived thermal metamorphism due to impacts and or solar radiation

the effect of topography on earthquake ground motion a review and new results a brief review of experimental and theoretical results about the effect of topography on seismic motion shows that they are consistent only on a qualitative basis amplification at mountain tops for wavelengths comparable with mountain widths is predicted and observed but the numerical simulations often underestimate the actual observed effects we propose that this disagreement is because current models are not complex enough we therefore computed the response to incident sh waves of a set of different complex configurations that include two dimensional surface topography with or without periodic ridges and subsurface layering the results show that 1 the topographic effect in itself is difficult to isolate from other effects like surface layering and therefore the amplification on top of geomorphologically complex sites cannot be predicted by a priori estimations based solely on topography and 2 the high crest base amplification ratio observed in the field cannot usually be matched even with complex two dimensional structures with incident plane sh waves which suggests that more complex models are needed to incorporate more complex wave fields e g sv surface and three dimensional geologic configurations

determination of martian meteorite lithologies and mineralogies using vibrational spectroscopy we have acquired thermal infrared emission spectra of four martian meteorite samples alh77005 nakhla zagami and eet79001 representing three major lithologies iherzolite clinopyroxenite and basalt the spectra of these meteorites are significantly different from each other and we can distinguish the three lithologies easily on the basis of their spectral morphologies using a linear deconvolution model the modal mineralogies of alh77005 nakhla and zagami were derived from their spectra to within 2 19 of the modes derived by optical methods for zagami and eet79001 the correct mineral types were identified as present using the linear method although an exact spectral match using available end member spectra was not obtained probably due to the lack of a pigeonite end member spectrum or shock effects in the meteorites the meteorite spectra we have acquired will be used for comparison with data to be returned by the thermal emission spectrometer tes on the mars global surveyor orbiter and would also be useful for comparing to future rover or lander based thermal ir spectra based on our results comparisons of mineral end member and meteorite spectra with tes spectra of coarse regolith and rocky regions should aid identification and mapping of martian surface lithologies and unit mineralogy

mineralogy of phyllosilicate rich micrometeorites and comparison with tagish lake and sayama meteorites abstract four phyllosilicate rich micrometeorites mms were investigated by a synchrotron radiation x ray diffraction technique and transmission electron microscopy three are saponite rich mms and one is a serpentine rich one in the saponite rich mms we could not find serpentine and vice versa in the serpentine rich mm in the saponite rich mms major constituent minerals are saponite fe and ni bearing sulfides and magnetite two saponite rich mms contain fine grained magnesiowustite rich aggregates the aggregates consist of

landslide susceptibility assessment based on an incomplete landslide inventory in the jilong valley tibet chinese himalayas abstract the himalayan range is one of the most tectonically active mountain ranges on earth the jilong valley is a deeply dissected canyon in the chinese himalayas in tibet and in this valley landslide hazard and risk have increased significantly in response to active crustal movements intense rainfall and ever increasing human interference landslide susceptibility assessment in the valley is fundamental for risk mitigation and to inform land use and planning but remains a challenge owing to the inaccessible high altitude and incomplete landslide inventory in addition because of sustained glacial erosion weathering and denudation there is considerable uncertainty in the use of remote sensing interpretation of landslides in high altitude terrain in this paper therefore a systematic approach for landslide susceptibility assessment is proposed combining the interpretations from remotely sensed dataset and both heuristic and statistical susceptibility models to overcome the problem of the limited spatial coverage of landslide data and uncertainty in landslide interpretation the main steps include 1 landslide field investigation and interpretation and the compilation of a preliminary landslide inventory including certain and probable landslides 2 knowledge driven identification of landslide prone areas based on the heuristic model 3 classification and quantification of the uncertainty of probable landslides through heuristic landslide prone areas mapping and the production of a revised landslide inventory and 4 data driven susceptibility assessment using a statistical model in the statistical model the landslide samples have multivalent dependent variables between 0 and 1 therefore a multinomial statistical classifier and multiclass receiver operation characteristic curves are needed for model calibration and validation the statistical susceptibility mapping showed good performance in the study area with an average auc of 0 867 which is a significant improvement over the heuristic model the methodology presented can be used for landslide susceptibility mapping in data scarce environments not only in the himalayan region but also in other mountainous areas where there is a lack of data on past landslide occurrences

directional resonance variations across the pernicana fault mt etna in relation to brittle deformation fields summary the pernicana fault pf is the main structural element of mt etna and the northern boundary of a section sliding to the southeast observed ground motion records in the damage zone of the pf show strong variations of directional resonance in the horizontal plane the observed resonance directions exhibit an abrupt rotation of azimuth by about 30 across the fault varying from n166 on the north side to n139 on the south we interpret the directional resonance observations in terms of changes in the kinematics and deformation fields on the opposite sides of the fault the northern side is affected primarily by the left lateral strike slip movement whereas the southern side that is subjected also to sliding is under a dominant extensional stress regime brittle deformation models based on the observed kinematic field predict different sets of fractures on the opposite sides of the fault synthetic cleavages and extensional fractures are expected to dominate in the northern and southern sides respectively these two fracture fields have different orientations n74 and n42 respectively and both show a near orthogonal relation 88 in the northern sector and 83 to the south with the azimuth of the observed directional resonance we conclude that the direction of the largest resonance motions is sensitive to and has transversal relationship with the dominant fracture orientation the directional amplification is inferred to be produced by stiffness anisotropy of the fault damage zone with larger seismic motions normal to the fractures

asteroid 21 lutetia at 3 μm observations with irtf spex abstract we present observations of asteroid 21 lutetia collected 2003 2008 using the spex instrument on the nasa infrared telescope facility irtf covering 2 4 m we also reevaluate nsfcam observations obtained in 1996 rivkin a s lebofsky l a clark b e howell e s britt d t 2000 icarus 145 351 368 taken together these show deeper 3 m band depths of order 3 5 in the southern hemisphere of lutetia and shallower band depths of order 2 or less in the north such variation is consistent with observations at shorter wavelength by previous workers nedelcu d a et al 2007 astron astrophys 470 1157 1164 lazzarin m et al 2010 mon not r astron soc 408 1433 1437 who observed hemispheric level variations from c like spectra to x like spectra while the shallowness of absorption bands on lutetia hinders identification of its surface composition goethite appears plausible as a constituent in its southern hemisphere beck p quirico e sevestre d montes hernandez g pommerol a schmitt b 2011 astron astrophys 526 a85 a89 mathematical models of space weathered goethite are most consistent with lutetia s southern hemisphere spectrum but more work and further observations are necessary to confirm this suggestion

modal mineralogy of carbonaceous chondrites by x ray diffraction and mossbauer spectroscopy carbonaceous chondrites are among the most analyzed geological materials on earth however despite this attention and unlike most terrestrial rocks little is known on the abundance of individual phases within them here we show how a combination of several novel x ray diffraction xrd techniques including a high brightness x ray microsource and mssbauer spectroscopy allows a complete modal mineralogy to be ascertained from even the most highly unequilibrated fine grained chondrites for all minerals of abundance 1 wt knowledge of the modal mineralogy of a sample also allows us to calculate grain density we analyzed allende murchison tagish lake and orgueil based on our modal data the grain density estimates for allende murchison and orgueil are close to literature values in the case of tagish lake there is no published grain density although a bulk density measurement does exist taking our estimate of grain density and the measured bulk density we calculate an exceptionally high porosity of 41 for this meteorite similar to some chondritic idps and in line with a porosity calculated from an entry model for the tagish lake fireball although it is an oxidized cv magnetite is present in allende at a level of 0 5 wt or 0 3 vol a result that is substantiated by several other instrumental studies this may be an oxidized meteorite but that oxidation is not manifested in abundant magnetite in addition we note appreciable fayalitic olivine in orgueil detected by both xrd and mossbauer we employed microsource xrd to look at heterogeneity in mineral abundance in orgueil and found substantial variation with phyllosilicates varying inversely with olivine the data suggest that orgueil was initially composed primarily of anhydrous materials which have been partially but not completely altered although the data are preliminary comparison between our xrd modal assessment bulk chemistry grain density and mossbauer data suggests that our estimates of mineral abundance are robust the advent of microsource xrd allows similar modal data to be acquired from samples as small as a few hundred micrograms

directional topographic site response at tarzana observed in aftershocks of the 1994 northridge california earthquake implications for mainshock motions abstract the northridge earthquake caused 1 78 g acceleration in the east west direction at a site in tarzana california located about 6 km south of the mainshock epicenter the accelerograph was located atop a hill about 15 m high 500 m long and 130 m wide striking about n78 e during the aftershock sequence a temporary array of 21 three component geophones was deployed in six radial lines centered on the accelerograph with an average sensor spacing of 35 m station c00 was located about 2 m from the accelerograph we inverted aftershock spectra to obtain average relative site response at each station as a function of direction of ground motion we identified a 3 2 hz resonance that is a transverse oscillation of the hill a directional topographic effect the top base amplification ratio at 3 2 hz is about 4 5 for horizontal ground motions oriented approximately perpendicular to the long axis of the hill and about 2 for motions parallel to the hill this resonance is seen most strongly within 50 m of c00 other resonant frequencies were also observed a strong lateral variation in attenuation probably associated with a fault caused substantially lower motion at frequencies above 6 hz at the east end of the hill there may be some additional scattered waves associated with the fault zone and seen at both the base and top of the hill causing particle motions not spectral ratios at the top of the hill to be rotated about 20 away from the direction transverse to the hill the resonant frequency but not the amplitude of our observed topographic resonance agrees well with theory even for such a low hill comparisons of our observations with theoretical results indicate that the 3d shape of the hill and its internal structure are important factors affecting its response the strong transverse resonance of the hill does not account for the large east west mainshock motions assuming linear soil response mainshock east west motions at the tarzana accelerograph were amplified by a factor of about 2 or less compared with sites at the base of the hill probable variations in surficial shear wave velocity do not account for the observed differences among mainshock acceleration observed at tarzana and at two different sites within 2 km of tarzana

can seismic waves be trapped inside an inactive fault zone the case study of nocera umbra central italy in march 1998 a small aperture 350 m linear array of five broadband stations was installed across a pliocene strike slip fault crossing the town of nocera umbra central italy three component seismograms of local earthquakes recorded during the umbria marche seismic sequence have shown that the degradation of mechanical properties in damaged rock causes a significant amplification of ground motion within the fault zone marra et al 2000 during the operation of the array an m w 5 3 subcrustal earthquake occurred at a depth of 48 km and an epicentral distance of 10 km from nocera umbra the near vertical incidence of this event offers a unique opportunity for constraining the 2d geometry of the laterally heterogeneous low velocity structure responsible for the large amplification across the fault based on the observed symmetry of the amplification pattern a 2d wedge shaped model of the fault zone is used for the computation of antiplane sh synthetic waveforms to be compared with observations along the array two parameters of the wedge model can be constrained by independent geophysical and geological data 1 shear wave velocity in pristine rock outside the fault zone v s 2200 m sec and 2 the lateral extent of the damaged rock zone l 160 m the other two model parameters namely the wedge depth h and shear wave velocity of the fault zone v f s are varied computer simulations show that trapped waves which have been observed so far for earthquakes occurring inside the fault zone can develop inside a 2d wedge model when struck by external vertically incident seismic radiation results of numerical modeling indicate that in spite of its extreme simplicity such an idealized model is successful in reproducing many of the essential characters of ground motion within the fault zone of nocera umbra even though the best fit solution is not unique and the model parameters trade off each other a study of parameter sensitivity comparing synthetics with recorded data indicates that the variability of h and v f s can be restricted to a limited range of values the quality of fit is optimal when the shear velocity reduction lies in the range of 40 50 and the depth of the trapping zone is comprised between 1 and 2 km

palinspastic restoration and paleogeographic reconstruction of the peri tyrrhenian area during the neogene abstract this paper presents the results of research carried out on the paleogeographic and geodynamic post collisional evolution of the peri tyrrhenian area from the southern alps to sicily during this post collisional evolution a back arc area thrust belt foredeep system developed in which the following tectono sedimentary zones can be distinguished from the external to the internal ones the foreland zone connected to the foredeep through a slope generally controlled by normal faults the foredeep an assymmetric depression with strong subsidence related to the compressional activity of the thrust zone the chain whose outward migration from the late oligocene onward was discontinuus with important stages of crisis partially connected to the mechanical response of different crustal thicknesses existing in the foreland the discontinuous satellite basins developed within the thrust belt the back arc basins developed in the inner part of the chain where the superposition of the extensional tectonics over previous compressional domains causes the fragmentation of the thrust belt leading to its destruction according to this model seven palinspatic maps are discussed regarding the following time intervals late oligocene 25 24 m y burdigalian 22 20 m y langhian 17 16 m y serravallin 15 13 m y tortonian 10 9 m y late messinian 5 5 5 3 m y and early pliocene 5 3 4 6 m y during five of these time intervals significant geodynamic modifications occurred in the whole peri tyrrhenian area leading to paleogeographic changes in any case the geodynamic evolution of the whole area seems clearly controlled by the activity of important bundles of tectonic lines transversal to the chain which in the same time interval in the outermost part of the thrust belt separated areas with different values of shortening and in tthe most internal zones separated segments having different amount of extension these tectonic lines certainly have a crustal significance and have probably acted along previous formed discontinuities