classification of new ice in the greenland sea using satellite ssm i radiometer and seawinds scatterometer data and comparison with ice model abstract in the ice covered waters of the greenland sea the polarisation ratio of quikscat seawinds ku band 13 4 ghz scatterometer measurements and the polarisation ratio of dmsp ssm i 19 ghz radiometer measurements are used in combination to classify new ice and mature ice in particular the formation of the new frazil pancake ice odden 8 w 75 n march 11th 18th 2001 is used in the study the results of the ice cover classification in the greenland sea are compared to model parameters from a sea ice model the classification of each ice pixel is performed using its backscatter and radiative properties as reflected in the polarisation ratio our results based on these comparisons show that the transformation into older mature sheet ice occurs within 5 10 days during one day the new ice cover increased by 33 000 km 2 the new ice appears in march 2001 as a peninsula maximum extent 56 000 km 2 appended to the belt of older ice drifting along the east coast of greenland these results are consistent with the ice model and with radarsat images furthermore using the ice model it is demonstrated that the new ice mature ice threshold in the classification corresponds to the physical transition of the ice cover from pancake ice to a consolidated young ice sheet the classification of each pixel into ice or water is done using two scatterometer parameters namely the polarisation ratio and the daily standard deviation of the backscatter

chemical alteration and mineral growth under high pco2 conditions insights from the mineral chemistry of carbonate phases in the caprese reservoir northern apennines central italy abstract carbon cycle is one of the most complex geochemical cycles of the earth as it involves atmosphere hydrosphere biosphere and lithosphere among these different geochemical spheres mechanisms and reaction rates governing migration and fixation of carbon i e fluxes such as the stability of the different carbonates minerals under specific conditions in crustal reservoirs are still matter of detailed studies in this work sem and xrd investigations and emp analyses were combined to study the mineralogical and chemical compositions of carbonate phases occurring in strongly altered triassic volcanic rocks hosting a co 2 reservoir namely the caprese reservoir located in eastern tuscany central italy the caprese crustal fluid reservoir lying at 3300 m depth beneath the quaternary san cassiano basin hosts a supercritical co 2 n 2 rich phase and a na cl rich saline up to 81 5 g l brine the mineralogical assemblage consists of authigenic microcrystalline quartz ca fe mg carbonates na k clay minerals and fe oxides the primary minerals being almost completely chemically altered by secondary processes scanning electron microscope images and cation ca fe mg contents in carbonates highlighted that zoned ankerite was re grown on calcite crystals due to interactions processes with co 2 rich fluids the geochemical and mineralogical data provided useful insights for understanding both the processes that formed the c bearing minerals and their growth in deep saline reservoirs

cryosphere applications of nscat data though designed to measure vector winds over the ocean new imaging techniques facilitate the use of nasa scatterometer data nscat in cryosphere studies nscat provides data of unprecedented coverage resolution and quality which when coupled with the scatterometer image reconstruction with filtering sirf algorithm enables images of spl sigma sup o at resolutions approaching 8 km over stationary targets such images are useful in ice mapping and classification and multidecadal studies are possible by comparison with seasat scatterometer sass data the utility of nscat data in polar ice studies is illustrated through a review of two cryosphere applications of nscat data 1 sea ice mapping and tracking and 2 ice sheet change in greenland and antarctica the wide swath and frequent revisit coupled with incidence and azimuth angle diversity makes nscat data very effective in mapping the extent of sea ice in greenland snow and ice facies are clearly delineated on the basis of the seasonally dependent radar backscattering cross section due to sensitivity of radar backscatter to diagenetic changes occurring at and beneath the surface comparison of nscat and sass data enables study of change in greenland between 1978 and 1996

the acquisition of source path and site effects from microearthquake recordings using q tomography application to the united kingdom source site and propagation parameters are inverted from a u k database of weak motion events 2 0 m l 4 7 this results in the complete spectral parameterization of over 3200 velocimetric records of 273 events from the year 1992 to 2006 the s wave is extracted from the vertical records and is processed using a multitaper fourier transform we initially use a nonlinear least squares log space optimization to obtain estimates of the attenuation parameter for each spectrum the estimates of t are then used to geometrically constrain a depth dependent q model using a technique adapted from velocity tomography we then invert for the remaining frequency dependent parameters and a collective amplitude parameter from the velocity spectra while fixing the newly computed attenuation parameters based on raytracing through our q model the resultant amplitude parameters are then split into source moments apparent geometrical spreading and site correction factors we find a frequency independent depth dependent q structure a linear relationship proportional to 0 7 m l between moment magnitude m w and local magnitude m l is found in the range of 2 4 7 m l the majority of stress drops are found to range on the order of 0 1 10 mpa a multiple segment apparent geometrical spreading model is found to best describe the amplitude decay with distance accounting for factors such as geometrical spreading and scattering along with multiple phase interference in the analysis window site response functions are found to broadly correlate with regional geology mean amplification occurring in the cenozoic sedimentary rock sites to the southeast of england relative to the harder palaeozoic rock sites of wales and scotland we use a bootstrap analysis technique to analyze the dependence of our results on the data in order to estimate the variance of the results and check the robustness of different inversions synthetic spectra are also computed in order to obtain minimum variance and bias of model parameters associated with the method in applying a geometrical q constraint through the use of q tomography we find that the robustness of the results is significantly increased a thorough analysis of the trade offs involved in the inversion is performed using synthetic datasets we find strong trade offs between the parameters but we are able to show that this covariance is reduced when adopting the q tomography approach

depositional systems composition and geochemistry of triassic rifted continental margin redbeds of the internal rif chain morocco the middle to upper triassic redbeds at the base of the ghomaride and internal dorsale calcaire nappes in the rifian sector of the maghrebian chain have been studied for their sedimentological petrographic mineralogical and chemical features redbeds lie unconformably on a variscan low grade metamorphic basement in a 300 m thick upward fining and thinning megasequence successions are composed of predominantly fluvial red sandstones with many intercalations of quartzose conglomerates in the lower part that pass upwards into fine grained micaceous siltstones and massive mudstones with some carbonate and evaporite beds this suite of sediments suggests that palaeoenvironments evolved from mostly arenaceous alluvial systems middle triassic to muddy flood and coastal plain deposits the successions are characterized by local carbonate and evaporite episodes in the late triassic the growth of carbonate platforms is related to the increasing subsidence norian rhaetian during the break up of pangea and the earliest stages of the western tethys opening carbonate platforms became widespread in the sinemurian sandstones are quartzose to quartzolithic in composition testifying a recycled orogenic provenance from low grade palaeozoic metasedimentary rocks palaeoweathering indices chemical index of alteration chemical index of weathering and plagioclase index of alteration suggest both a k enrichment during the burial history and a source area that experienced intense weathering and recycling processes these processes were favoured by seasonal climatic alternations characterized by hot episodically humid conditions with a prolonged dry season these climatic alternations produced illitization of silicate minerals iron oxidation and quartz rich red sediments in alluvial systems the estimated burial temperature for the continental redbeds is in the range of 100 to 160 c with lithostatic tectonic loading of ca 4 to 6 km these redbeds can be considered as regional petrofacies that mark the onset of the continental rift valley stage in the western pangea middle triassic before the opening of the western part of tethys in the middle jurassic the studied redbeds and the coeval redbeds of many alpine successions betic tellian and apenninic orogens show a quite similar history they identify a mesomediterranean continental block originating from the break up of pangea which then played an important role in the post triassic evolution of the western mediterranean region

seismic wave attenuation from borehole and surface records in the top 2 5km beneath the city of basel switzerland summary we investigate attenuation q 1 of sediments of 2 5 3 5 km thickness underneath the city of basel switzerland we use recordings of 195 induced events that were obtained during and after the stimulation of a reservoir for a deep heat mining project in 2006 and 2007 the data set is ideally suited to estimate q as all events are confined to a small source volume and were recorded by a dense surface network as well as six borehole sensors at various depths the deepest borehole sensor is positioned at a depth of 2 7 km inside the crystalline basement at a mean hypocentral distance of 1 8 km this allows us to measure q for frequencies between 10 and 130 hz we apply two different methods to estimate q first we use a standard spectral ratio technique to obtain q and as a second measure we estimate q in the time domain by convolving signals recorded by the deepest sensor with a q operator and then comparing the convolved signals to recordings at the shallower stations both methods deliver comparable values for q we also observe similar attenuation for p and s waves qp qs as expected q increases with depth but with values around 30 50 it is low even for the consolidated permian and mesozoic sediments between 500 and 2700 m

influence of the 3d distribution of q and crustal structure on ground motions from the 2003 mw 7 2 fiordland new zealand earthquake the m w 7 2 earthquake of 21 august 2003 provides an unprecedented opportunity to evaluate the applicability of the new zealand acceleration response spectrum attenuation model mcverry et al 2006 in the fiordland region and to consider effects from 3d q heterogeneity this was the largest shallow earthquake in new zealand in the past 40 yrs it was well recorded by the geonet seismograph and strong motion network we compare the observed 5 damped response spectral accelerations sas to the new zealand model values for both crustal reverse and subduction interface earthquakes on average both models underpredict the observed sas by approximately 0 4 in lnsa for 0 400 km distance however the data show great variability using the south island 3d q model we compute the path averaged attenuation rate cq for synthetic fiordland hypocenters to distributed sites compared to the standard model the relatively high q in south island produces lower attenuation rates although the low q crustal root of the southern alps produces a 10 times greater attenuation rate for certain paths the average attenuation rate estimated from the sa data is similar to cq for frequencies 5 hz and constant above 5 hz for an acceleration model for fiordland earthquakes 0 60 km depth an applicable anelastic attenuation rate is the mean cq from the synthetic hypocenters which is 0 006 km 1 at 2 5 hz for the observed sas the most significant regional effect is high relative sas at some sites that may be due to postcritical moho reflections from the southern alps crustal root

frictional melting of gabbro under extreme experimental conditions of normal stress acceleration and sliding velocity 1 with the advent of high velocity shear apparatus several experimental studies have been performed in recent years improving our understanding of the evolution of fault strength during seismic slip however these experiments were conducted under relatively low normal stress 20 mpa and using small cylindrical samples where a large gradient in slip velocity exists across the sliding surface given the above limitations the extrapolation of these experimental results to natural conditions is not trivial here we present results from an experimental study on gabbroic rocks using a newly developed rotary shear apparatus capable of reaching higher normal stress up to 50 mpa on ring shaped samples 30 50 mm internal external diameter and allowing precise control of the imposed slip velocity function the results confirm that steady state shear stress during the melt lubricated phase of the experiment depends on normal stress in the form of a power law equation as predicted by theoretical models however the exponent appears closer to 0 5 contrary to the theoretical prediction of 0 25 we observe no systematic dependence of shear stress on acceleration but increasing deceleration drastically decreases the recovery of friction during final slip we find that the slip weakening distance decreases inversely with increasing normal stress in agreement with theoretical considerations and decreases with increasing slip rate extrapolation of the slip weakening distance to natural conditions predicts a slip velocity for ancient seismic events of 0 3 1 m s when compared with field estimates these values compare well with seismological estimates

a model for vertical to horizontal response spectral ratios for europe and the middle east in the framework of probabilistic seismic hazard analysis the preferred approach for obtaining the response spectrum of the vertical component of motion is to scale the horizontal spectrum by vertical to horizontal v h spectral ratios in order to apply these ratios to scenario or conditional mean spectra the v h ratios need to be defined as a function of variables such as magnitude distance and site classification a new model for the prediction of v h ratios for peak ground acceleration and spectral accelerations from 0 02 to 3 0 s is developed from the database of strong motion accelerograms from europe and the middle east a simple functional form expres sing the v h ratios as a function of magnitude style of faulting distance and site class is found to be appropriate and the associated aleatory variability is found to be at least as low as that obtained in other studies using more complex models the predicted ratios from the new european model are found to be in broad agreement with recent models derived from predominantly western north america data

the production of ice and dense shelf water in the okhotsk sea polynyas this paper examines the ice and dense water production in the okhotsk sea coastal polynyas for the 1990 1995 winters the dominant polynyas occur on the northwest and northern shelves and in shelikhov bay we use an algorithm developed for the special sensor microwave imager ssm i to derive for each polynya the area and composition of thin ice and open water and a heat flux algorithm to derive the ice and brine production historic oceanographic observations show that the northwest shelf is the only north pacific region where the 26 8 potential density surface outcrops to the surface and is also that part of the okhotsk shelf where the densest water is observed to occur in support of these observations we find that the northwest shelf polynya is the dominant ice and brine producer contributing on average about 55 of the total production shelikhov bay is the second largest producer with about 25 of the total this region has been previously neglected by both oceanographic and remote sensing studies using a combination of two dense water production models we find that the 6 year average dense water production lies between 0 2 0 4 sv the ice and brine production for the dominant northwest shelf vary interannually by a factor of 3 while the production from all the northern polynyas varies by factor of 2 the source of the variability for the northwest shelf comes from the fact that the southwest to northeast trend of the coastline and the mean winter geostrophic wind velocities are roughly parallel which means that small variations in the wind direction yield large changes in the ice production

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

depletion of perennial sea ice in the east arctic ocean 1 the extent of perennial sea ice in the east arctic ocean 0 180 e decreased by nearly one half with an abrupt reduction of 0 95 106 km2 while the west arctic ocean 0 180 w had a slight gain of 0 23 106 km2 between 2004 and 2005 as observed by satellite scatterometer data during november december the net decrease in the total perennial ice extent is 0 72 106 km2 about the size of texas perennial ice in the east arctic ocean continued to be depleted with an areal reduction of 70 from october 2005 to april 2006 with the east arctic ocean dominated by seasonal sea ice a strong summer melt may open a vast ice free region with a possible record minimum ice extent largely confined to the west arctic ocean simultaneous scatterometer measurements of sea ice and winds will be crucial for sea ice monitoring and forecasts

syntectonic sedimentation in a middle triassic rift northern apennines italy abstract the anatomy of the sedimentary and volcanic fill of a middle triassic continental rift at the western margin of the tethys is illustrated by the study of a 250 m thick sequence on the tyrrhenian coasts of the northern apennines this sequence contains two cycles of sedimentation 1 a the lower cycle comprises a basal transgressive sequence from continental alluvial fans to shallow marine carbonates and an upper sequence which correspond to an increasing tectonic activity submarine syntectonic facies assemblage the lower part of the last assemblage is characterized by a thick 22 m rapidly deposited sequence of coarse carbonate breccias with minor calcareous sandy turbidites this is overlain by channelized red beds of submarine fans composed of close interstratification and juxtaposition of carbonate breccias with red clastic matrix and red sandy quartz pebble conglomerates and silty sands interbedded alkaline pillow lava record penecontemporaneous submarine eruptions the lavas are capped by thin red cherty diaspri crusts the lower cycle of sedimentation ends with a karstic surface on relatively deep marine carbonate layers this suggests a rapid emersion due to the arrest and reversal of the downsinking of the initial aborted or failed rift 2 b the upper cycle of sedimentation starts with more mature fluvial red beds and changes upward into shallow marine sands and carbonates this upper cycle represents an early stage of evolution of a new major rift this second major rift led in jurassic times to the opening of an oceanic area between europe and western italy

amplitude tomography of lg waves in xinjiang and its adjacent regions amplitude tomography of lg waves at frequencies from 1 to 5 hz are investigated in this work to reveal the lateral attenuation heterogeneities of the study area the xinjiang uygur autonomous region of china and its adjacent regions by using a large set of broadband seismic waveform data first we inverted the average q lg at each of 10 frequencies from 0 5 to 5 hz then the study area was divided into evenly spaced 1 1 grid cells after conducting both a checkerboard test and a resolution test finally the high resolution q lg tomographic images at the 10 frequencies were obtained the moment magnitudes of the events and the site terms of the stations we used were obtained simultaneously the attenuation pattern of q lg at each frequency shows obvious lateral heterogeneities in xinjiang and its adjacent regions which are coincident with the geological features of the area the tarim basin and the middle and the eastern part of the southern tian shan belong to high q regions the northeastern margin of the pamir plateau the northwestern margin of the tibetan plateau the western part of the southern tian shan and northern tian shan are prominent low q areas the attenuation pattern of lg waves shows that large scale tectonic boundaries zones with rapid topographic or crustal thickness gradient are in good accordance with the boundaries of the high and low q lg most of the historical strong earthquakes occurred on the interior or edge of low q lg areas

how does the amur river discharge flow over the northwestern continental shelf in the sea of okhotsk abstract the paths of the amur river discharge on the continental shelf in the sea of okhotsk are still unknown despite their significance in transporting dissolved and particulate iron in this study we conduct a coupled ice ocean simulation for the northern sea of okhotsk from june 1998 to september 2000 to answer the question does the amur river discharge deposit materials to the pathway of the dense shelf water in a series of numerical experiments we identified two routes the western and eastern routes that could transport the river water more than 100 km offshore over the northwestern continental shelf the two routes share the clockwise gyre in the sakhalin gulf and the northeastward flow on the northwestern continental shelf these features are connected through the westward jet along the slope from the sakhalin gulf the western route and the northward transport over the shelf break canyon the eastern route the river water the dense shelf water and the easterly wind are in a fine geophysical balance for those features and all are required for the formation of the two routes the model results show that these unique joint effects in the sea of okhotsk allow the amur river discharge to be effectively transported over the northwestern continental shelf unlike a general river discharge that flows along the coast and deposit materials into the pathway of the dense shelf water

attenuation of seismic shear wave energy in switzerland summary modelling the attenuation of shear wave energy is an important component of seismic hazard analysis previous studies have shown how attenuation particularly in the uppermost layers of the crust is regionally dependent the impact of this is that the decay of energy radiating from an earthquake will vary from place to place to quantify the regional attenuation in switzerland we model the fourier spectral amplitude of small to moderate earthquakes recorded on the local seismic networks high frequency decay is parametrized by q and while apparent geometrical spreading models account for the frequency independent decay of energy we analyse ground motion encompassing the significant duration of shaking to provide models that are useful for the purpose of seismic hazard analysis two methods are used to estimate the whole path attenuation parameter t first a simultaneous fit of the source model and attenuation effects across the entire spectral bandwidth for earthquakes with m 2 and secondly a linear fit of an attenuation model to the high frequency part of the spectrum for earthquakes with m 3 5 the t parameter is found to vary with hypocentral distance consistent with a weakly attenuating crust and strongly attenuating uppermost layer 1 d tomographic inversions indicate a profile of increasing q with depth down to the moho frequency independent decay is parametrized using a three part model which allows for the inclusion of moho reflection phases in the spectrum in the range of 20 140 km in the swiss foreland and from 70 to 140 km in the swiss alps

eocene fan delta submarine fan deposition in the wagwater trough east central jamaica the wagwater trough is a fault bounded basin which cuts across east central jamaica the basin formed during the late palaeocene or early eocene and the earliest sediments deposited in the trough were the wagwater and richmond formations of the wagwater group these formations are composed of up to 7000 m of conglomerates sandstones and shales six facies have been recognized in the wagwater group facies i unfossiliferous massive conglomerates facies ii channelized non marine conglomerates sandstones and shales facies iii interbedded fossiliferous conglomerates and sandstones facies iv fossiliferous muddy conglomerates facies v channelized marine conglomerates sandstones and shales and facies vi thin bedded sheet sandstones and shales the wagwater and richmond formations are interpreted as fan delta submarine fan deposits facies associations suggest that humid region fan deltas prograded into the basin from the adjacent highlands and discharged very coarse sediments on to a steep submarine slope at the coast waves reworked the braided fluvial deposits of the subaerial fan delta into coarse sand and gravel beaches sediments deposited on the delta front slope were frequently remobilized and moved downslope as slumps debris flows and turbidity currents at the slope basin break submarine fans were deposited the submarine fans are characterized by coarse inner and mid fan deposits which grade laterally into thin bedded turbidites of the outer fan and basin floor

breccia hosted manganese rich minerals of alpi apuane italy a marine redox generated deposit mn rich beds occur within the brecce di seravezza formation bsfm intercalated between norian metadolostone megalodontic marble and hettangian marble in the alpi apuane italy the bsfm is a rockfall talus deposit that accumulates at the base of the footwall scarp of normal faults bordering extensional marine coastal basins the type sequence of metabreccia ends with a bed of chloritoid schist interpreted as the metamorphic equivalent of lateritic soils the four main types of mn mineral assemblages are 1 braunite piemontite and rare hausmannite 2 piemontite braunite hollandite and minor rhodochrosite and kutnahorite 3 braunite hollandite and rare piemontite the other minerals are quartz calcite muscovite phlogopite baryte and minor hematite rutile and apatite during the alpine orogeny pressures of 4 6 kb and temperatures of 350 380 c were attained mn assemblages with hematite and phlogopite indicate o2 10 8 for t 350 c and o2 10 6 when braunite appears on the mn rich rocks ti fe nb sn ta hf th ga rb pr k na nd were identified as detrital in origin and are positively correlated with al u is positively correlated with co pb bi mo the rare earth element patterns normalized to seawater show a negative slope towards the heavy rare earth elements with positive ce anomalies in some samples positive ce and eu anomalies in other samples and negative ce and positive eu anomalies in a third group the eu concentrations are nearly constant and the eu anomalies reflect differences in the concentration of other rare earth elements for ce a positive correlation with al2o3 sio2 indicate that a detrital signature prevails on that produced by duration of seawater exposure but a significant good correlation of la tm lu with mg could indicate at least for these elements a seawater signature only in some samples ba eu sr show anomalously high concentrations likely of hydrothermal origin however generally in all the chemical variation diagrams the bsfm samples fall outside the field of hydrothermal and hydrogenous deposits as defined in the literature for other mn deposits in addition metabasites and metavolcaniclastic beds are absent from the bsfm sequence and bsfm coastal basins were for the most part separated from the open ocean and related streams that must be excluded as possible mn sources owing to the arid climate of late triassic the runoff was negligible and the groundwater oxidizing and alkaline were unable to mobilize mn the bsfm basins are then the most suitable depositional environment for mn the water column was stagnant and stratified only where bottom of the basin was deeper than the oxic anoxic boundary reducing marine bottom waters percolated within the fractured basement and leached mn from disseminated minerals of metamorphic rocks and then rising along fault and fractures supplied mn to the bottom waters afterwards when tectonic uplift and sealevel drop brought the bottom into the oxic field mn precipitated and formed the mn rich matrix of the bsfm deposits

sea ice identification using dual polarized ku band scatterometer data this paper describes a classification algorithm using dual polarized scatterometer measurements to identify the edge of the sea ice cover the distinct polarization scattering signatures of sea ice and open water are discussed and illustrated with the dual polarized radar measurements from the seasat a scatterometer sass the analysis of sass data suggests that the ratio of vertical and horizontal polarization backscatter denoted as the copol ratio is a useful discriminator of sea ice and open ocean a simple classification algorithm using the thresholds of the copol ratio and backscatter levels is proposed the feasibility of this algorithm is demonstrated using the sass data from the single sided dual polarization mode the results indicate that the dual polarized measurements from the nasa scatterometer nscat can be used to produce routine maps of sea ice edges

quantifying the uncertainty in site amplification modeling and its effects on site specific seismic hazard estimation in the upper mississippi embayment and adjacent areas the mississippi embayment located in the central united states and its thick deposits of sediments over 1 km in places have a large effect on earthquake ground motions several previous studies have addressed how these thick sediments might modify probabilistic seismic hazard maps the high seismic hazard associated with the new madrid seismic zone makes it particularly important to quantify the uncertainty in modeling site amplification to better represent earthquake hazard in seismic hazard maps the methodology of the memphis urban seismic hazard mapping project cramer et al 2004 is combined with the reference profile approach of toro and silva 2001 to better estimate seismic hazard in the mississippi embayment improvements over previous approaches include using the 2002 national seismic hazard model fully probabilistic hazard calculations calibration of site amplification with improved nonlinear soil response estimates and estimates of uncertainty comparisons are made with the results of several previous studies and estimates of uncertainty inherent in site amplification modeling for the upper mississippi embayment are developed i present new seismic hazard maps for the upper mississippi embayment with the effects of site geology incorporating these uncertainties

sedimentology of a middle cambrian outer shelf margin with evidence for syndepositional faulting eastern california and western nevada abstract the middle to upper cambrian emigrant formation at horse thief canyon california is a transitional section between the outer shelf bonanza king formation and the basin facies represented by the emigrant formation in nevada at horse thief canyon the emigrant is subdivided into four members the limestone siltstone member the papoose lake tongue the megabreccia member and the limestone chert member for a portion of middle cambrian time the shelf structure was that of a ramp bedded and burrowed pelletal dolostones were deposited in the deeper waters of the outer shelf sediment for the outer shelf may have been derived from a mid shelf shallow subtidal to peritidal zone cycle patterns of burrowed and bedded dolostones are probably related to periods of little sediment input accompanied by intense burrowing of the bottom followed by periods of heightened current activity and bedded dolostone deposition later in the middle cambrian the shelf structure changed to a platform megabreccia and breccia beds representing debris flow deposits and interbedded allodapic calcarenite and calcisiltite are evidence for the existence of a significant slope between shelf and basin this slope may have been caused by syndepositional faulting and collapse of a portion of the outer shelf the fault hypothesis is based on a rust colored marker unit recognized in the emigrant at horse thief canyon and in the outer shelf bonanze king section 13 km to the south along with the presence of distinctive algal boundstone clasts in the megabreccia member the megabreccia beds lie above the marker unit but all known source rocks for the algal boundstone occur stratigraphically well below the marker uncertainty egarding the syndepositional fault hypothesis centers on whether the horse thief and last chance range sections are in the same or different allocthons

investigations of newly formed sea ice in the cape bathurst polynya 2 microwave emission 1 this study examines the role of newly formed sea ice geophysical state on microwave emission coincident with sea ice geophysical sampling ship based passive microwave emission data dual polarized at 19 37 and 85 ghz were collected in the cape bathurst polynya during 18 october and 13 november 2003 using polarization ratios prs we found that bare thin ice was separable from snow covered ice thin snow equal to 0 02 0 13 m thickness is significantly correlated with the spectral gradient ratios grv 85 19 r2 0 55 p value 0 2 the relationship between atmospherically corrected r37 and bare ice thickness showed an exponential relationship very comparable to that reported by martin et al 2004 which is ascribed to the reduction of bare ice surface salinity based on both observational and modeling studies however the relationship quickly becomes invalid for even thin snow covered ice due to significant impact of thin wet liquid water fraction 0 02 0 04 snow on microwave emission our results suggest that the sea ice algorithms nasa team and nasa team 2 could underestimate total ice concentration over thin bare ice by 35 on average while both algorithms underestimate the total ice concentration by 20 over snow covered ice using pr 85 sea ice could be delineated from open water using a properly adjusted threshold value accounting for cloud or fog effects possibly with the exception of dark nilas and or bare consolidated pancakes

the shape of ground motion attenuation curves in southeastern canada the shape of the attenuation curve of the fourier spectrum of acceleration is established for southeastern canada from empirical data the dataset is comprised of 1200 digital vertical component seismograms from 100 earthquakes recorded on 30 stations of the eastern canada telemetered network the distance range of the observations is 10 to 1700 km focal depths are from 5 to 30 km results indicate that the attenuation curve has three distinct sections at distances less than 70 km corresponding to attenuation of the direct wave amplitudes decay slightly more rapidly than 1 r r 1 1 between 70 and 130 km where the direct wave is joined by sms spectral amplitudes are approximately constant beyond 130 km corresponding to the lg phase amplitudes decay at a rate that is consistent with r 0 5 and q 670 f 0 33 the findings support the hypothesis of burger et al 1987 that postcritical reflections from the moho discontinuity play an important role in determining the shape of the attenuation curve however the influence of sms is subtle allowing the shape to be approximated by simple functional forms for example the commonly assumed bilinear form r 1 r 0 5 with frequency dependent q fits well if the transition from direct wave to lg spreading is placed at approximately 60 km a linear form r 1 over all distances with constant q 2000 also provides a satisfactory fit overall we find little evidence for the dependence of attenuation on focal depth or tectonic province

inheritance of jurassic rifted margin architecture into the apennines neogene mountain building a case history from the lucretili mts latium central italy the western lucretili mts in the central apennines latium italy have been recently re mapped in great detail and are the subject of combined stratigraphic sedimentological and structural investigations in this paper we present a new stratigraphic interpretation of the jurassic paleogeography of western lucretili mts where a rift derived intrabasinal paleo high of the alpine tethys has been identified for the first time by means of facies analysis and biostratigraphic dating recognised facies associations combined with dated stratigraphic sections allow to define the morphology of the structural paleo high and to identify the associated gravity driven deposits olistoliths accumulated in the surrounding basin furthermore we investigated the modes of interaction between jurassic extensional structures and the subsequent contractional patterns developed during the tertiary mountain building in detail the role played during apennines tectonics by the paleo escarpments bounding the paleo high and by the surrounding olistoliths has been analysed the paleo escarpments either acted as focussing features for ene directed frontal thrust ramp localisation and were offset with small shortening amounts or reactivated as nne striking high angle transpressional faults or preserved the original geometries as a result of variable orientation of paleo escarpments with respect to the neogene compressive stress field with ene oriented sigma1 newly formed ene striking tear faults connect these either inherited or neo formed discontinuities this complex stratigraphic and structural pattern is substantially different from the previous interpretations of this portion of the central apennines based on a hypothesised layer cake stratigraphy deformed by neo formed neogene thrusts this contribution strengthens the importance of integrating facies analyses and structural investigations to detect the influence of pre orogenic structures on compressive structural patterns in an area where commercial seismic lines are not available and cannot help in reconstructing the subsurface geometries

post variscan verrucano like deposits in italy and the onset of the alpine tectono sedimentary cycle abstract in the italian regions the stratigraphic successions of the verrucano s l consist essentially of continental alluvial plain to coastal neritic siliciclastic redbeds deposited at different times in the alps mid late permian the northern apennines mid late triassic p p locally in southern tuscany also followed by the jurassic pseudoverrucano complex and the calabro peloritani arc mid late triassic exceptionally reaching earliest jurassic whereas in sardinia the recognition of the verrucano succession is still a topic of discussion the most typical metamorphic lithofacies in the pisan mts of tuscany is represented by the verrucano s s conglomerates and breccias including quartz clasts and minor metamorphic and volcanic lithics grading laterally and vertically to quartzitic sandstones and pelites in the pisa symposium the term verrucano was suggested only for those detrital deposits laid down in the alpine mediterranean areas after the final act of the variscan orogeny and also to use local geographical names consequently the typical terms verrucano toscano the verrucano lombardo the verrucano brianconnais and other similar deposits being linked to the variscan belt were generally accepted the ages of these verrucanos since they are devoid of fossils can only be interpreted indirectly the verrucano lombardo of central southern alps was recently ascribed to a mid late permian interval late guadalupian lopingian p p taking into account that the connected val gardena sandstones of the nearby venetian region are interdigitated with the late permian bellerophon fm the verrucano brianconnais of the maritime alps is again mostly related to late permian being covered by the lower triassic alluvial deltaic quartzites in the easternmost ligurian apennines near la spezia the mesozoic section of punta bianca which begins with a fluvial conglomerate transgressive and unconformable on a metamorphosed paleozoic variscan basement is composed of two main cycles of which the upper one correlates to the typical pisan verrucano s s and the overlying mt serra quartzites the latter yielding carnian pelecypods and vertebrate footprints the verrucano from the mid tuscan ridge to mt leoni and in the argentario promontory is delimited above by the tocchi formation and presumably developed from middle late ladinian up to late triassic carnian times in contrast in calabria e g the longobucco unit of sila grande and in sicily e g the taormina longi unit of peloritani mts the so called pseudo verrucano deposits pertain to mid late triassic and are capped by a basal jurassic succession determined by the discovery of an early hettangian palynoflora all over their distribution areas the above mentioned alpine verrucanos rest through an unconformity marked by a gap of varying and imprecise duration on late paleozoic volcanic sedimentary successions or directly on the underlying variscan metamorphic basement schematically the post variscan succession in italy can be subdivided into three main tectono sedimentary megacycles the first generally ranges from the late carboniferous to or slightly above the early permian the second from mid late permian to middle triassic while the third cycle begins with the mid late triassic p p attaining the jurassic in some parts of southern tuscany and the calabro peloritani arc after the late carboniferous and early permian transtensional tectonics represented by many strike slip continental basins cycle i widespread middle permian geodynamic reorganization mid permian episode auctt led to the development of a dominant extensional regime and the birth of tectonic plates and oceans neotethys meliata maliak etc between africa and europe the erosion of the variscan relief was followed by ingression from s e sectors of shallow marine branches of neotethys cycle ii the major rifting events that led to the jurassic birth of the ligurian piedmont ocean started during the middle late triassic and were related to the eastern opening of the atlantic ocean these rifting events gave rise to the development of the adria and europe corsica sardinia conjugate passive margins characterized by an asymmetric structural and sedimentary evolution in this geological context the verrucano like deposits of italy can be interpreted as a discontinuous and asynchronous tectofacies that marks the final dismantling of the se border of the variscan chain

apparent break in earthquake scaling due to path and site effects on deep borehole recordings 1 we reexamine the scaling of stress drop and apparent stress rigidity times the ratio between seismically radiated energy to seismic moment with earthquake size for a set of microearthquakes recorded in a deep borehole in long valley california in the first set of calculations we assume a constant q and solve for the corner frequency and seismic moment in the second set of calculations we model the spectral ratio of nearby events to determine the same quantities we find that the spectral ratio technique which can account for path and site effects or nonconstant q yields higher stress drops particularly for the smaller events in the data set the measurements determined from spectral ratios indicate no departure from constant stress drop scaling down to the smallest events in our data set mw 0 8 our results indicate that propagation effects can contaminate measurements of source parameters even in the relatively clean recording environment of a deep borehole just as they do at the earth s surface the scaling of source properties of microearthquakes made from deep borehole recordings may need to be reevaluated

s wave velocity measurements applied to the seismic microzonation of basel upper rhine graben summary an extensive s wave velocity survey had been carried out in the frame of a recent seismic microzonation study of basel and the border areas between switzerland france and germany the aim was to better constrain the seismic amplification potential of the surface layers the survey included single station h v spectral ratios and ambient vibration array measurements carried out by the swiss team as well as active s wave velocity measurements performed by the german and french partners this paper is focused on the application of the array technique which consists in recording ambient vibrations with a number of seismological stations several practical aspects related to the field measurements are outlined the signal processing aims to determine the dispersion curves of surface waves contained in the ambient vibrations the inversion of the dispersion curve provides a 1 d s wave velocity model for the investigated site down to a depth related to the size of the array since the size of arrays is theoretically not limited arrays are known to be well adapted for investigations in deep sediment basins such as the upper rhine graben including the area of the city of basel in this region 27 array measurements with varying station configurations have been carried out to determine the s wave velocity properties of the geological layers down to a depth of 100 250 m for eight sites the outputs of the array measurements have been compared with the results of the other investigations using active sources the spectral analysis of surface waves sasw and s wave reflection seismics borehole information available for a few sites could be used to calibrate the geophysical measurements by this comparison the advantages and disadvantages of the array method and the other techniques are outlined with regard to the effectiveness of the methods and the required investigation depth the dispersion curves measured with the arrays and the sasw technique were also combined and inverted simultaneously to use the advantages of both methods finally the paper outlines and discusses the contribution of the s wave velocity survey to the new seismic microzonation of the basel region in this regard one major outcome of the survey is the quantification of vertical and lateral changes of the s wave velocity due to changing lithology or changing compaction and degree of weathering of the layers

earthquake ground motion prediction equations for eastern north america new earthquake ground motion relations for hard rock and soil sites in eastern north america ena including estimates of their aleatory uncertainty vari ability have been developed based on a stochastic finite fault model the model incorporates new information obtained from ena seismographic data gathered over the past 10 years including three component broadband data that provide new in formation on ena source and path effects our new prediction equations are similar to the previous ground motion prediction equations of atkinson and boore 1995 which were based on a stochastic point source model the main difference is that high frequency amplitudes f 5 hz are less than previously predicted by about a factor of 1 6 within 100 km because of a slightly lower average stress parameter 140 bars versus 180 bars and a steeper near source attenuation at frequencies less than 5 hz the predicted ground motions from the new equations are generally within 25 of those predicted by atkinson and boore 1995 the prediction equations agree well with available ena ground motion data as evidenced by near zero average residuals within a factor of 1 2 for all frequencies and the lack of any significant residual trends with distance however there is a tendency to positive residuals for moderate events at high frequencies in the distance range from 30 to 100 km by as much as a factor of 2 this indicates epistemic uncertainty in the prediction model the positive residuals for moderate events at 100 km could be eliminated by an increased stress parameter at the cost of producing negative residuals in other magnitude distance ranges adjustment factors to the equations are provided that may be used to model this effect

thickness and production of sea ice in the okhotsk sea coastal polynyas from amsr e 1 from comparisons with thickness of sea ice from advanced very high resolution radiometer avhrr and ice profiling sonar data we have developed an advanced microwave scanning radiometer eos amsr e thin ice thickness algorithm for the sea of okhotsk this algorithm can estimate ice thickness of 0 2 m without snow using the polarization ratio of amsr e brightness temperature at a 36 5 ghz channel from a linear relationship with avhrr ice thickness when a snow cover exists on the thin ice surface as occurred a few times in each winter it is shown that the algorithm cannot detect the thin ice sea ice and dense shelf water dsw production in coastal polynya are estimated on the basis of heat flux calculation with the daily amsr e ice thickness for three winters december march of 2002 2003 to 2004 2005 the ice production is largest in the northwest shelf nws polynya which accounts for 45 of the sum of ice production in major coastal polynyas the ice production in major coastal polynyas would cover the maximum ice area of the okhotsk sea if the average ice thickness is assumed to be 1 m variability of the ice production is mainly modulated by air temperature in the nws polynya which is the main dsw production area the annual dsw formation rate is estimated to be 0 36 sv

triassic continental rifting of pangaea direct evidence from the alpujarride carbonates betic cordillera se spain abstract evidence is presented for triassic rift related palaeo structures from the alpujarride complex carbonates of the betic cordillera se spain direct evidence of synsedimentary extensional tectonics is provided by macro to meso scale normal faults overstepped by younger strata most faults define domino like horst and graben structures the faults are associated with an expanded synrift sedimentary prism in which soft sediment deformation gravity flow deposits and unconformities are widely developed syntectonic mafic igneous intrusions also occur the age of this phase of extension is constrained as ladinian carnian c 237 216 ma from a palaeogeographical standpoint the thick triassic carbonates of the betic internal zone together with comparable successions in northern calabria southern apennines occupied a belt with elevated subsidence connecting the neo tethys to the east with the eastern north american intracontinental rift system to the west their carbonate facies intermediate between classical alpine and germanic type triassic facies recorded the main episodes of rifting affecting central pangaea

new moment magnitude scale evidence of stress drop magnitude scaling and stochastic ground motion model for the french west indies in this study we analyse records from the les saintes seismic sequence following the mw 6 3 earthquake of 2004 november 11 which occurred close to guadeloupe french west indies 485 earthquakes with magnitudes from 2 to 6 recorded at distances between 5 and 150 km are used s waves fourier spectra are analysed to simultaneously determine source path and site terms the results show that the duration magnitude routinely estimated for the events that occurred in the region underestimate moment magnitude by 0 5 magnitude units over the whole magnitude range from the inverted seismic moments and corner frequencies we compute brune s stress drops we show that stress drops increase with increasing magnitude the same pattern is observed on apparent stresses i e the seismic energy to moment ratio however the rate of increase diminishes at high magnitudes which is consistent with a constant stress drop model for large events using the results of the inversions we perform ground motion simulations for the entire data set using the smsim stochastic simulation tool the results show that a good fit 0 25 with observed data is achieved when the source is properly described by its moment magnitude and stress drop and when site effects are taken into account although the magnitude dependent stress drop model is giving better results than the constant stress drop model the interevent variability remains high which could suggest that stress drop depends on other parameters such as the depth of the hypocentre in any case the overall variability is of the same order of magnitude as usually observed in empirical ground motion prediction equations

the atlas east variscan elbe shear system and its role in the formation of the pull apart late palaeozoic basins the variscan orogeny occurred as a result of the late devonian to late carboniferous collision and accretion of gondwana derived microcontinents and continental masses with those of laurussia the irregular boundaries of the colliding continents caused isochronous transpressional and transtensional tectonics accompanied by a complex pattern of intracontinental shear zones at the scale of the southern european variscides these shear zones and their configuration controlled the subsequent evolution of permian to middle triassic paleogeography the geographic distribution from morocco to the eastern alps of the late carboniferous permian up to triassic basins most of which are considered as pull apart basins was related with the development of the late palaeozoic intracontinental shear network our analysis of the stratigraphic tectonic and volcanic features of the late carboniferous permian continental basins across the laurussia gondwana boundary reveals the role of the east variscan shear zone during this time as a precursory lineament for the development of the permian to triassic rifting of pangaea and the following opening of oceanic basins e g the neothetyan ocean

tectonics of the punta bianca promontory insights for the evolution of the northern apennines northern tyrrhenian sea basin the structural setting of the eastern headland of the la spezia gulf punta bianca promontory provides some constraints on the contractional and extensional framework of the northern apennines northern tyrrhenian sea basin geodynamic system and allows a detailed reconstruction of a complex evolutionary path out of sequence thrusting is supposed in the inner side of the chain two different extensional events are identified the older early middle miocene may be related to the imbrication of the deeper metamorphic units of the apenninic thrust wedge younger extension fits very well into an eastward asymmetrical faulting framework related to the opening of the northern tyrrhenian sea basin from the late miocene to the pliocene pleistocene well exposed low angle normal faults developed during this event extensional structures were then overprinted and reactivated by a mainly strike slip regime in the quaternary

the middle triassic magmatic tectonic arc development in the southern alps abstract the geodynamic meaning of the middle triassic magmatic and tectonic events in the southern alps is still uncertain the main problem is the significance of the compressional tectonic structures recognized in the central dolomites in fact these structures are incompatible with the extensional geodynamic interpretation crustal rifting assumed by several authors therefore the compressional tectonic elements of the dolomites have been mostly ignored or not seriously taken into account or considered as local phenomena due to the volcanic tectonic interplay other more modern interpretations are founded on regional transcurrent and or transpressive tectonics recent discovery of a middle triassic thrust system located in the piave river area some tens of kilometres east of the central dolomites lends more credence to the compressional middle triassic event the magmatic series of volcanic and plutonic middle triassic rocks display an orogenic character with typical calc alkaline trends recognized across the whole southern alps as well as in the dinaric and hellenic domains such a character is rather uncommon in the crustal evolution by rifting but is more in accord with a compressional geodynamic setting furthermore the time space distribution of the south alpine magmatic rocks coupled with their petrochemical affinity are close to the modern volcanic arcs nevertheless the general geodynamic context of the southern alps owing to their pronounced ensialic character does not fit the oceanic model

styles of tectonic inversion within syn orogenic basins examples from the central apennines italy the geometry of several thrust related folds in the central apennines of italy results from a switch in deformation regime from extension to contraction this switch in tectonic regime occurred during the deposition of syn orogenic sediments and the emplacement and migration of the thrust belt foredeep system towards the foreland in neogene time the styles of positive tectonic inversion result from normal faults that were steepened rotated and truncated by thrusts with local development of minor folds due to buttressing normal fault controlled escarpments are also locally preserved in the forelimbs and backlimbs of thrust related anticlines the location and amplitudes of contractional structures across the belt reflects the distribution of pre thrusting normal faults within precursor syn orogenic basins a result that may improve our understanding of the evolution of apennine as well as other thrust belt foredeep systems

attenuation relations of strong ground motion in japan using site classification based on predominant period a spectral acceleration attenuation model for japan is presented in the present study the data set includes a very large number of strong ground motion records up to the 2003 off tokach main and aftershocks site class terms instead of individual site correction terms are used the site classes of recording stations are from a recent study on site classification for strong motion recording stations in japan according to a classification scheme that has been used in japanese engineering design the use of site class terms enables tectonic source type effects to be identified and accounted for in the present model the effects of a faulting mechanism for crustal earthquakes also are accounted for for crustal and interface earthquakes a simple form of an attenuation model with respect to distance is able to capture the main strong motion characteristics and achieves unbiased estimates for subduction slab events a simple distance modification factor is employed to achieve plausible and unbiased predictions the effects of source depth tectonic source type and faulting mechanism of crustal earthquakes are significant the need for magnitude squared terms is evaluated and the use of magnitude squared terms reduces the interevent error further

global variations of stress drop for moderate to large earthquakes 1 we investigate the global variation of earthquake stress drops using spectra of about 2000 events of mb 5 5 between 1990 and 2007 we use an iterative least squares method to isolate source displacement spectra from travel path and receiver contributions based on a convolutional model the observed p wave source spectra are corrected with a globally averaged empirical correction spectrum and estimates of near source attenuation assuming a brune type source model we estimate corner frequencies and compute stress drops stress drop estimates for individual earthquakes range from about 0 3 to 50 mpa but the median stress drop of about 4 mpa does not vary with moment implying earthquake self similarity over the mw 5 2 to 8 3 range of our data a comparison of our results with previous studies confirms this observation over most of the instrumentally observable magnitude range while the absolute values of our estimated stress drops depend upon the assumed source model we identify relative regional variations of stress drop that are robust with respect to the processing parameters and modeling assumptions which includes an inherent assumption of constant rupture velocity we find a dependence of median stress drop on focal mechanism with a factor of 3 5 times higher stress drops for strike slip earthquakes and also find a factor of 2 times higher stress drops for intraplate earthquakes compared to interplate earthquakes

the mesozoic continental rifting in the mediterranean area insights from the verrucano tectofacies of southern tuscany northern apennines italy in the alpine mediterranean region the continental redbeds and shallow marine siliciclastics related to the early depositional phases of the late permian mesozoic continental rifting are referred to as the most common representative of the verrucano tectofacies the verrucano type successions exposed in southern tuscany are diachronous spanning from triassic to earliest jurassic in age and accumulated within the tuscan domain a paleogeographic region of continental crust that due to the opening of the piedmont ligurian ocean formed part of the adria passive margin they belong to the metamorphic verrucano group and the non metamorphic pseudoverrucano fm viewed overall these verrucano type successions appear to manifest five episodes or pulses of an ongoing continental rifting with the exception of the first episode that developed entirely within a terrestrial setting each one is represented by basal verrucano type continental siliciclastics overlain by compositionally mixed marine deposits which resulted from four diachronous post middle triassic transgressions this suite of tectonic pulses produced the progressive westward widening backstepping of the tuscan domain in the rifting south tuscany area

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

derivation of a reference shear wave velocity model from empirical site amplification abstract the definition of a reference bedrock condition representative of a region of interest is of great significance in seismic hazard assessment it is highly beneficial when ground motion prediction equations are referenced to a specific site condition particularly in the case of site specific seismic hazard analyses when known the effect of any given site with respect to the reference can then be applied to the predicted ground motion however the choice of a reference velocity profile is not straightforward mainly due to the high variability of the velocity structure in the shallower layers a new method to define the regional reference rock profile is proposed the method relates quarter wavelength average velocity at a site to frequency dependent amplification a reference bedrock velocity profile can then be directly defined in relation to expected amplification characteristics over a number of sites we compare 27 quarter wavelength velocity profiles from seismic station locations in switzerland with empirical amplification functions derived from spectral modeling from this comparison a set of frequency dependent calibration relationships is established assuming that the reference profile is defined by a lack of any relative amplification the quarter wavelength velocity profile that corresponds to unitary spectral amplification can be extracted the reference velocity profile can then be obtained through an inversion procedure and defines the reference for the ground motion prediction equation gmpe the proposed reference velocity profile is compared with previous reference velocity profiles a good agreement is found between the different methods additionally an estimation of the transfer function for the swiss reference rock condition is provided this can be used to correct recorded or estimated spectral amplitudes for the local response of the reference site finally it is shown that the coefficients from the aforementioned correlations can be used to estimate a generic amplification function at any site with a known quarter wavelength velocity profile

a stochastic earthquake ground motion prediction model for the united kingdom low seismicity regions such as the united kingdom uk pose a challenge for seismic hazard analysis in view of the limited amount of locally recorded data available in particular ground motion prediction is faced with the problem that most of the instrumental observations available have been recorded at large distances from small earthquakes direct extrapolation of the results of regression on these data to the range of magnitudes and distances relevant for the seismic hazard analysis of engineered structures generally leads to unsatisfactory predictions the present study presents a new ground motion prediction equation gmpe for the uk in terms of peak ground acceleration pga peak ground velocity pgv and 5 damped pseudospectral acceleration psa based on the results of numerical simulations using a stochastic point source model calibrated with parameters derived from local weak motion data the predictions from this model are compared with those of previous gmpes based on uk data other gmpes derived for stable continental regions scrs as well as recent gmpes developed for the wider european area

mapping of sea ice production for antarctic coastal polynyas 1 active sea ice production in antarctic coastal polynyas causes dense water formation finally leading to antarctic bottom water aabw formation this study gives the first mapping of sea ice production in the antarctic ocean based on heat flux calculation with ice thickness data derived from satellite data the highest ice production occurs in the ross ice shelf polynya region the ice production there decreased by 30 from the 1990s to the 2000s which can be one candidate for causing the recent freshening of aabw the cape darnley polynya in east antarctica is found to be the second highest production area suggesting a possible aabw formation area according to our estimation around 10 of southern ocean sea ice is produced in the major antarctic coastal polynyas the mapping provides surface heat and salt flux conditions in the ice covered region which have not been well understood

tertiary syntectonic carbonate platform development in indonesia cenozoic tropical carbonate sedimentation was strongly influenced by local and regional tectonics in se asia this paper outlines the evolution of the syntectonic eocene to middle miocene tonasa formation of south sulawesi evaluating controls on sedimentation facies distribution and sequence development development of a facies model for this cenozoic tropical carbonate platform provides a meaningful analogue for similar less well studied se asian carbonates which commonly comprise targets for hydrocarbon exploration this study also has considerable implications for the study of syntectonic carbonates controls on carbonate sedimentation carbonate platform development in backarc areas and se asian tectonics detailed facies mapping logging petrographic and biostratigraphic analyses indicate that the tonasa formation was deposited initially as part of a transgressive sequence in a backarc setting by late eocene times shallow water carbonates were being deposited over much of south sulawesi forming a widespread 100 km long platform area shallow water sedimentation continued unabated in some areas of the platform until the middle miocene elsewhere active normal faulting resulted in fault block platforms with local subaerial exposure of footwall blocks and the formation of basinal graben in adjacent hangingwall areas platform top facies were aggradational and dominated by larger benthic foraminifera low angle slopes particularly hangingwall dip slopes were characterized by the development of ramps faults controlled in part by pre existing structures were periodically active and formed steep escarpment margins variable regional subsidence strongly influenced the development of the tonasa carbonate platform whereas platform wide effects caused by regional eustacy have not been identified computer modelling of the tonasa platform confirms that the accommodation space and sedimentary geometries observed can be produced by block faulting and regional subsidence alone modelling also reveals that regional subsidence and extension oblique to the main stretching direction were low on the margins of the backarc basin shallow water accumulation rates for this foraminifera dominated tropical carbonate platform were an order of magnitude lower than those for modern warm water platforms dominated by corals or ooids

modeling finite fault radiation from the ωn spectrum the high frequency seismic field near the epicenter of a large earth quake is modeled by subdividing the fault plane into subelements and summing their contributions at the observation point each element is treated as a point source with an o92 spectral shape where co is the angular frequency ground motion contributions from the subsources are calculated using a stochastic model attenuation is based on simple geometric spreading in a whole space coupled with regional anelastic atten uation q operator the form of the co n spectrum with natural n follows from point shear dislocation theory with an appropriately chosen slip time function the seismic moment and comer frequency are the two parameters defining the point source spectrum and must be linked to the subfanlt size to make the method complete two coefficients aa and k provide this link assigning a moment to a subfault of specified size introduces the stress parameter ao the relationship between comer frequency dislocation growth rate and fault size is established through the coefficient k which is inherently nonunique these two parameters control the number of subsources and the ampli tudes of high frequency radiation respectively derivation of the model from shear dislocation theory reveals the unavoidable uncertainty in assigning ogn spectrum to faults with finite size this uncertainty can only be reduced through empirical vali dation the method is verified by simulating data recorded on rock sites near epicenters of the m8 0 1985 michoacan mexico the m8 0 1985 valparaiso chile and the m5 8 1988 saguenay qurbec earthquakes each of these events is among the largest for which strong motion records are available in their respective tectonic environ ments the simulations for the first two earthquakes are compared to the more de tailed modeling of somerville et al 1991 which employs an empirical source function and represents the effects of crustal structure using the theoretical impulse response both methods predict the observations accurately on average the precision of the methods is also approximately equal the predicted acceleration amplitudes in our model are generally within 15 of observations an unexpected result of this study is that a single value of a parameter k provides a good fit to the data at high frequencies for all three earthquakes despite their different tectonic environments this suggests a simplicity in the modeling of source processes that was unanticipated

the interaction of extensional and contractional deformations in the outer zones of the central apennines italy abstract the relationships among normal faults and thrusts in the apennines of italy are often unclear and the local absence of syn tectonic stratigraphic controls have led to contrasting interpretations on the relative chronology for both classes of structures the activity of normal faults has been variously regarded as due to pre syn or post orogenic extension and the contrasting evidence from different sites has produced an ongoing debate on the normal fault thrust interaction the results of a kinematic analysis on selected composite structures of the outer zones of the central apennines make it possible to unequivocally establish a relative chronology of extensional and contractional deformations detailed mapping outcrop scale observations and structural overprinting relationships support a positive inversion tectonic history where normal faults and fault controlled escarpments formed first and were later deformed by thrusts and related folds all normal faults control the distribution of foredeep deposits thus indicating that the recognised episode of positive inversion is related to the incipient stages of construction of the apennine thrust belt the systematic collection of structural data may help to unravel the evolution of adjacent sectors of the apennine chain as well as of other belt foredeep foreland systems whose extension contraction relationships are poorly constrained

the 1356 basel earthquake an interdisciplinary revision summary within historical times one of the most damaging events in intra plate europe was the 1356 basel earthquake given its significance for assessing regional seismic hazard in central europe an interdisciplinary project was launched in 2005 to re explore this event our effort aimed to incorporate techniques from history seismology archaeology paleoseismology and engineering new and reinterpreted historical data from basel and its surroundings plus archaeological findings on buildings that survived the event and still exist enabled this macroseismic assessment palaeoseismological studies combined with historical evidence provided additional data for the surrounding areas archaeology offers sparse information on some castles and churches sometimes supported by historical records a contemporary source allows some reconstruction of the stronger fore and aftershocks this expanded information base improves our sense of the event s damage and consequences for the city of basel the relatively abundant archaeological data allowed us to assess statistically the macroseismic intensity at ix although the pattern of damage was scattered data points for the expected area of damage around basel are not distributed regularly the absence of historical and archaeological findings for southern germany might be due to archival problems future investigation may improve this situation our results confirm that the basel earthquake was the most destructive known for central europe intensities up to viii are found within a radius of about 30 km analysing the macroseismic field confirms our former assessment of the event and shows an epicenter located about 10 km south of basel the most probable range for the moment magnitude mw is between 6 7 and 7 1

geochemical and geochronological data on triassic volcanism of the southern alps of lombardy italy genetic implications a widespread volcanism mainly consisting of pyroclastic products and lava flows is found in the southern alps of lombardy the volcanics are interbedded with anisian ladinian carbonatic sequences and continental terrigenous or transitional deposits of ladinian carnian age the petrographic and geochemical data for this volcanism indicate a calc alkaline affinity with characters similar to those of convergent continental margins in this sector of the alps the geological evidences show that in the middle triassic general extensional movements were the dominant deformation event and do not support the existence of a subduction zone during this period the apparent contrast between the tectonic environment and the type of magmas erupted in the anisian carnian is tentatively explained by partial melting during the early stage of rifting of an upper mantle deeply modified during the previous hercynian orogenesis and contaminated by crustal material this hypothesis is in agreement with the preliminary sr isotopic ratios 0 705 and 0 709 k ar and rb sr ages on biotites date the beginning of the volcanism at around 225 m y

rscm thermometry in the alpi apuane nw tuscany italy new constraints for the metamorphic and tectonic history of the inner northern apennines abstract in this study raman spectroscopy on carbonaceous material rscm is applied for the first time in the northern apennines with particular focus on the alpi apuane nw tuscany italy and surrounding areas in order to constrain peak metamorphic temperatures and their variability in the different continent derived units of the nappe stack peak temperatures in the range of 530 320 c were found in the alpi apuane whereas in the nearby metamorphic core of the monte pisano and punta bianca lower peak temperatures of 305 315 c and 350 c were found respectively the tuscan nappe in la spezia area west of alpi apuane shows temperatures in the range of 295 246 c whereas the same unit in the lima valley east of the alpi apuane shows temperatures lower than 230 c the collected data allowed refining the thermal architecture of the belt and the relationships between deformation early and late folds and low angle normal detachments and the metamorphic architecture of the alpi apuane core these results provide new contraints for the thermo mechanical evolution and exhumation history of the inner northern apennine and its geodynamic setting in particular our data support the interpretation of the alpi apuane as a cold metamorphic core complex in which the preserved paleothermal structure and part of the exhumation are related with crustal thickening while the final exhumation stages depth 15 km and at ambient crustal temperature 350 c are associated with crustal thinning still ongoing in the area

a comparative study on attenuation and source scaling relations in the kanto tokai and chubu regions of japan using data from hi net and kik net abstract attenuation relations are derived for central japan broadly spanning the kant tokai and chubu regions using recordings of small earthquakes 2 0 m jma 4 0 japan meterological agency magnitude and moderate to large magnitude earthquakes 3 0 m jma 7 2 we independently analyze data from both small magnitude and moderate to large magnitude earthquakes to provide an insight into the use of attenuation relations derived in regions of low seismic activity a strong correlation is found between the attenuation parameters derived from each dataset we find that q is strongly depth dependent and that apparent geometrical decay increases with increasing hypocentral distance this is modeled by using a three segment decay function with the initial decay forced to 1 r moment magnitudes are close to the published m jma magnitude but are on average slightly higher an increase in stress drop with magnitude is required in order to model both the small magnitude and moderate to large magnitude datasets alternatively we show that a constant stress drop model is suitable to model the response spectra of both small magnitude and moderate to large magnitude earthquakes when considering the saturation of the source corner frequency due to a static site filter such as f max or we test our ability to predict strong ground motion by using our attenuation and source scaling relations derived from the small magnitude recordings to stochastically simulate peak ground acceleration peak ground velocity and 5 damped response spectral ordinates over a range of magnitudes and distances the residuals of this simulation are found to be largely independent of distance and magnitude we compare our attenuation relations against other relations derived for japan the residuals of these relations are analyzed and compared against those obtained from the model found in this study we find that in this study the prediction of strong ground motions is possible using small magnitude data and that the validity of the prediction extends across all magnitudes available for comparison 2 0 m jma 7 8 on the other hand by using an alternative published predictive relation for japan derived using large magnitude events peak ground acceleration is significantly overestimated for small magnitude earthquakes

some examples of the middle triassic marine transgression in south western mediterranean europe in southwestern mediterranean europe ne spain sardinia and nw apennines e g monti pisani and punta bianca the middle triassic transgression on a margin of an intracratonic basin appears to be controlled by the different morphology and tectonic activity of the margin itself

a stochastic ground motion model for switzerland abstract we present a stochastic ground motion model for switzerland a model for the far field fourier amplitude spectra of earthquakes is first proposed constrained by ground motions observed from small local and regional earthquakes in addition to macroseismic intensities observed from large damaging events in switzerland we then use this model in a stochastic simulation technique to generate predictions of peak ground acceleration and velocity and 5 damped response pseudo spectral acceleration we facilitate the prediction of ground motions from finite fault sources through the use of the r eff distance metric and show that magnitude and distance scaling behavior of events up to m w 7 5 is broadly consistent with next generation attenuation and japanese models ground motion prediction uncertainty is described in terms of between and within event uncertainties through residual analysis of response spectra finally single station sigma is derived accounting for the prediction uncertainty at a given site without the ergodic assumption consistency of the model is emphasized through its compatibility with other seismic hazard products the model is referenced to a generic rock profile that was developed by utilizing velocity profiles of the sites of seismic stations and is calibrated at higher magnitudes to the swiss regional macroseismic intensity prediction model furthermore the model is based on moment magnitudes from the recently developed earthquake catalogue of switzerland 2009 ecos09 the well defined reference for the model means that it can easily be adapted for a site specific application for instance through the use of proxies such as quarter wavelength velocity and travel time average shear wave velocity in the upper 30 m v s 30

the association of continental crust rocks with ophiolites in the northern apennines italy implications for the continent ocean transition in the western tethys abstract the late cretaceous sedimentary melanges from the external liguride units of the northern apennines include large slide blocks of ophiolites and lower and upper continental crust rocks representative of a continent ocean transition between the internal liguride oceanic domain and the thinned continental margin of the adria plate the slide blocks preserve a record of the long lived history of rifting which led to opening of the jurassic western tethys basin the external liguride ophiolites consist of 1 undepleted spinel peridoties partly re equilibrated under plagioclase facies conditions which were interpreted as unroofed subcontinental mantle 2 rare gabbroic rocks mainly troctolite to olivine bearing gabbro probably crystallised from n morb magmas and 3 basalts with n to t morb affinity covered by late callovian early oxfordian radiolarian cherts both gabbroic rocks and basalts locally intrude the mantle peridotites and postdate their re equilibration to plagioclase facies conditions the slide blocks of lower continental crust are composed of gabbro derived mafic granulites and felsic granulites the latter include quartzo feldspathic granulites and rare quartz poor to quartz free charnockitic rocks in both mafic and felsic granulites granulite facies re equilibration was followed by a retrograde metamorphic evolution to amphibolite greenschist and subgreenschist facies conditions retrogression is commonly accompanied by deformations progressively changing from plastic to brittle the upper crustal rocks occurring as slide blocks consist of hercynian granitoids with orogenic affinity mainly biotite bearing granodiorites and peraluminous two mica leucogranites locally the granitoids are intruded by basaltic dykes or capped by basaltic flows and radiolarian cherts the granitoids underwent polyphase brittle deformations under subgreenschist facies conditions which predated the basalt emplacement the tectono metamorphic evolution recorded by the slide blocks of the external liguride units started in the late carboniferous early permian about 290 ma with the emplacement at deep crustal levels of the gabbroic protoliths for the mafic granulites the associated felsic granulites likely represent the remnants of the lower continental crust intruded by the gabbro derived granulites mafic and felsic granulites subsequently underwent tectonic exhumation in permo triassic times as testified by the development of granulite to amphibolite facies ductile shear zones the granulites were finally exhumed to shallow levels probably in association with the subcontinental mantle in late triassic middle jurassic times the latter period was most likely characterized by extensive brittle faulting at shallow crustal levels thus giving rise to extensional allochthons formed by stretched slices of granitoids the western tethys opening is finally testified by the basalt intrusion and effusion in the late jurassic followed by deep sea pelagic sedimentation the external liguride crustal stratigraphy can be regarded as a fossil example of the transitional realm at the continent ocean boundary this reconstruction fits well with the available data on the present day continental margins derived from passive lithosphere stretching

source attenuation and site parameters of the 1997 umbria marche seismic sequence from the inversion of p wave spectra a comparison between constant qp and frequency dependent qp models 1 the attenuation of p waves the site responses and the source parameters seismic moment corner frequency source dimension of 490 seismic events that occurred during the 1997 colfiorito umbria marche seismic sequence have been inferred from the inversion of p wave velocity spectra the boatwright source model has been assumed to model the source spectra a global nonlinear inversion scheme was developed to avoid any a priori selection of the initial qp and the corner frequency to establish if a frequency dependent qp model fits the data better than a constant qp model two inversion results have been compared application of the akaike information criterion indicates that the constant qp model represents the best compromise between model simplicity and data misfit the station qp values are small in the range of 50 to 200 a one dimensional qp model is obtained by back projecting the inverted t our results indicate both well defined near site attenuation effects at some sites and heterogeneity in the inelastic properties of the crust with the exception of the amplification response at five seismic stations most of the recording sites did not show amplification peaks at particular frequencies the stress drop clearly increases as a function of the seismic moment which indicates a deviation from self similarity whereas it does not show an increase with depth probably owing to the effects of fluid pressurization in the crust a stress drop of about 39 mpa is inferred the relationship between the seismic moment and the local magnitude for p waves has been calibrated

earthquake scaling characteristics and the scale in dependence of seismic energy to moment ratio insights from kik net data in japan 1 we investigate earthquake source characteristics and scaling properties using the results of a spectral inversion of more than 29 000 accelerometric borehole recordings from 1 826 earthquakes mjma 2 7 8 throughout japan we find that the calculated source spectra can be well characterized by the omega square model and show on average self similar scaling over the entire magnitude range with median stress drops of 1 1 and 9 2 mpa for crustal and subcrustal events respectively the seismic energy to moment ratio as theoretically expected if the omega square model is valid shows a strong dependency on stress drop only which in conjunction with data selection practice in some studies to cope with limited recording bandwidth can explain the often observed apparent scale dependence our observations suggest that there is no significant deviation from similarity of the energy radiation in the investigated magnitude range and that the observed scatter is mainly related to the scatter in stress drop

a local ground motion predictive model for turkey and its comparison with other regional and global ground motion models we examined the differences between the ground motion estimations of local and global prediction equations and explored some seismological parameters that may explain these differences to achieve this objective we first derived a set of ground motion prediction equations gmpes for estimating peak horizontal accel eration velocity and pseudospectral acceleration using the recently compiled turkish ground motion database the new gmpes are comparable with the recent global gmpes in terms of model sophistication and they are based on a well studied national dataset using global gmpes from the next generation attenuation of ground motions project power et al 2008 and the pan european akkar and bommer 2010 model we observed that the discrepancy between local and global gmpes is more prominent at small magnitudes provided that the gmpes possess similar mag nitude limits our more detailed comparisons with the pan european akkar and bom mer 2010 predictive model as well as with the estimations from a combined italian and turkish accelerometric dataset indicate that depth can be of importance for delineating the differences between local and global gmpes