a referenced empirical ground motion model for arias intensity and cumulative absolute velocity based on the nga east databasea referenced empirical ground motion model for arias intensity and cumulative absolute velocity based on the nga east database

insufficient statistical model development of ground motion relations for regions with low seismicity abstract it is a special issue to model an earthquake ground motion relation gmr ground motion prediction equation for the seismic hazard analysis of regions with low seismicity a region specific gmr may be difficult to develop if there are only a few observations therefore different approaches criteria and procedures have been developed in seismology and earthquake engineering to apply appropriate gmrs from one region to another this is a special type of statistical model development we criticize this and corresponding research from the statistical point of view our evaluation criteria result from state of the art mathematical statistical analysis especially regression analysis

palaeogeographical controls on the cambrian trilobite immigration and evolutionary patterns reported in the western gondwana margin abstract southward drifting of the western gondwanan margin during the cambrian has been demonstrated by means of both palaeomagnetic methods and lithological indicators of climate such as carbonates and evaporites recent improvements in biostratigraphical correlations permit an enhanced understanding of the climatic and palaeobiogeographical constraints that controlled the distribution of cambrian benthic communities palaeogeographical and biogeographical reconstructions based on trilobites are reported in this paper in order to test interaction between migration speciation and extinction rates the variability of the documented biogeographical patterns is directly related to species diversity in which wider distribution coincides with transgressive trends and subsequent connection of neighbouring platforms early cambrian trilobite faunas show a high degree of both substrate control and endemicity although transgressions led to parallel shifts in faunal compositions by contrast mid cambrian trilobite faunas are relatively uniform across western gondwana and latest mid and late cambrian associations document influence of an increased similarity with asian trilobite faunas

hybrid empirical ground motion prediction equations for eastern north america using nga models and updated seismological parameters in the field of earthquake engineering ground motion prediction models are frequently used to estimate the peak ground acceleration pga and the pseudos pectral acceleration psa in regions of the world where ground motion recordings are plentiful such as western north america wna the ground motion prediction equations are obtained using empirical methods in other regions such as eastern north america ena with insufficient ground motion data alternative methods must be used to develop ground motion prediction equations gmpes the hybrid empiri cal method is one such method used to develop ground motion prediction equations in areas with sparse ground motions this method employs the stochastic simulation method to adjust empirical gmpes developed for a region with abundant strong motion recordings in order to estimate strong motion parameters in a region with a sparse database the adjustments take into account differences in the earthquake source wave propagation and site response characteristics between the two regions in this study a hybrid empirical method is used to develop a new gmpe for ena using five new ground motion prediction models developed by the pacific earthquake engineering research center peer for wna a new ena gmpe is derived for a magnitude range of 5 to 8 and closest distances to the fault rupture up to 1000 km ground motion prediction equations are developed for the response spectra pseudoacceleration 5 damped and the pga for hard rock sites in ena the resulting ground motion prediction model developed in this study is compared with two ena ground motion models used in the 2008 national seismic hazard maps as well as with available observed data for ena

construction of the cambrian and ordovician seawater 87sr 86sr curve abstract the estimated path of seawater 87 sr 86 sr during the cambrian and ordovician is based on 172 analyses the sample suite is largely from locations in oklahoma new york tennessee and texas where rocks of this age are widely exposed and well studied the oldest reliable samples examined in this study are of middle cambrian age and yield an 87 sr 86 sr near 0 70888 sw 19 the estimated ratio rises to near 0 70915 sw 8 in the lower upper cambrian the highest value during the phanerozoic and probably for all geologic time the estimated path drifts lower to near 0 70903 sw 4 at the cambrian ordovician boundary this further declines to near 0 70875 sw 32 at the end of the ibexian and reaches a value near 0 70821 sw 86 at the whiterockian mohawkian boundary the decline in the seawater 87 sr 86 sr continues into later mohawkian time to flatten abruptly near 0 70782 sw 125 this ratio is essentially constant through the latest ordovician the curve rises near to a ordovician silurian boundary value poorly constrained from our data near 0 70784 sw 123 the early paleozoic seawater curve shows the alternating dominance of continental and oceanic sources of sr continental sr dominated seawater from the beginning of the cambrian into late cambrian from that time as the cambrian transgression proceeded and radiogenic crystalline rocks were covered oceanic sr began to dominate sr from low ratio oceanic sources dominated through early mohawkian time an abrupt balance is struck between oceanic and continental sources to end the decline in the late ordovician and maintained until near the end of the ordovician the general curve shape follows the pattern suggested by proposed sealevel changes the rise and fall of seawater 87 sr 86 sr during the cambrian and ordovician characterized seawater variation during all the paleozoic

regionally adjustable generic ground motion prediction equation based on equivalent point source simulations application to central and eastern north america abstract we develop a generic ground motion prediction equation gmpe that can be adjusted for use in any region by modifying a few key model parameters the basis of the gmpe is an equivalent point source simulation model whose parameters have been calibrated to empirical data in california in such a way as to determine the decoupled effects of basic source and attenuation parameters on ground motion amplitudes we formulate the generic gmpe as a function of magnitude distance stress parameter geometrical spreading rate and anelastic attenuation this provides a fully adjustable predictive model allowing users to calibrate its parameters using observed motions in the target region we also include an empirical calibration factor to account for residual effects that are different from and or missing in simulations compared to observed motions in the target region as an example we show how the generic gmpe can be adjusted for use in central and eastern north america cena and calibrated with the next generation attenuation east database we provide median predictions of ground motions in cena for average horizontal component peak ground motions and 5 damped pseudospectral acceleration periods up to t 10 s for magnitudes m 3 8 and distances up to 600 km

three new upper cambrian stages for north america the existing upper cambrian stages for north america are obsolete three new stratotype defined stages are equivalent to and replace three successive biomeres marjuman stage replaces marjumiid biomere lower boundary at base ptychagnostus atavis zone steptoean stage replaces pterocephaliid biomere lower boundary at base aphelaspis zone sunwaptan stage replaces ptychaspid biomere lower boundary at base irvingella major subzone the base of the overlying ibexian series is placed at the base of the eurekia apopsis subzone

comparative analysis of methods used to define eustatic variations in outcrop late cambrian interbasinal sequence development interbasinal correlation of late cambrian cyclic carbonates from the appalachian and cordilleran passive margins the texas craton and the southern oklahoma aulacogen defines six major third order depositional sequences graphic correlation of biostratigraphically constrained strata was used to establish equivalency of stratigraphic sequences between the individual sections relatively isochronous biomere boundaries were used as time datums for lithostratigraphic correlation although the individual sections are composed of different types of meter scale cycles and component lithofacies that reflect the various environmental settings of the localities the overall upward shallowing character of individual sequences is evident the sequences are late cedaria mid crepicephalus late crepicephalus aphelaspis to earliest elvinia elvinia to early saukia and saukia to the cambrian ordovician boundary interbasinal correlation of stratigraphic sequences permits an evaluation of quantitative techniques for determining accommodation history correlation of fischer plots of cyclic successions from separate basins supports a eustatic control of late cambrian sequence development r2 r3 curves derived from subsidence analysis of the late cambrian sections provide good resolution of the second and third order scales of accommodation change and interbasinal correlations of r2 r3 curves also support eustatic control on sequence development comparing the accomodation curves and subsidence analysis with paleobathymetric trends of late cambrian cyclic strata suggests that themore curves may approximate the form of the eustatic sealevel signal a composite eustatic sealevel curve for late cambrian time in north america was created by qualitatively combining the accommodation curves defined by the different techniques for each of the four localities 129 refs 16 figs 3 tabs less

neodymium isotopic composition of cambrian ordovician biogenic apatite in the baltoscandian basin implications for palaeogeographical evolution and patterns of biodiversity biogenic apatite preserved in 148 samples of conodonts and organophosphatic shelled brachiopods from cambrian through ordovician successions of the baltoscandian basin baltica plate preserves a sensitive record of early palaeozoic sea water chemistry interpreted via neodymium isotope ratios consistent e nd t values of 9 6 to 8 3 for lower to middle cambrian samples suggest no significant lateral or temporal variation across the region average upper cambrian values are 7 2 to 7 7 sedimentary analysis suggests that the influence of continental weathering from baltica as a major source of radiogenic nd was negligible ordovician samples show a rise to 5 to 6 in the early arenig early mid llanvirn and late caradoc sea water mixing from the southeast iapetus ocean was a constant factor throughout cambrian ordovician times the rise reflects erosion of obducted volcanic arc complexes along the caledonian margin and probably also relates to pollution of the baltica sector of iapetus from the approaching avalonia plate patterns of evolutionary biodiversity and palaeobiogeographical linkages support the geochemical signatures in interpreting the tectonic history of the region extinction of lingulate brachiopod faunas in the tremadoc followed by subsequent recovery and emergence of benthic assemblages typical of the ordovician evolutionary fauna in the billingen early volkhov regional stages coincide with significant changes in geochemical characteristics of water masses across the baltoscandian basin the early and mid ordovician arenig to llandeilo brachiopod faunas of the north estonian confacies belt are characterized by high endemism and low turnover rates whereas increased immigration resulted in the extinction of a number of local lineages in the late llanvirn from the mid caradoc to mid ashgill when baltica was drifting on a course to collide eventually with avalonia and gradually approach laurentia brachiopod assemblages were characterized by higher turnover rates at the same time they gradually became more cosmopolitan and less influenced by the invasion of new faunas

site amplifications for generic rock sites seismic shear wave velocity as a function of depth for generic rock sites has been estimated from borehole data and studies of crustal velocities and these velocities have been used to compute frequency dependent amplifications for zero attenuation for use in simulations of strong ground motion we define a genetic rock site as one whose velocity at shallow depths equals the average of those from the rock sites sampled by the borehole data most of the boreholes are in populated areas for that reason the rock sites sampled are of particular engineering significance we consider two genetic rock sites rock corresponding to the bulk of the borehole data and very hard rock such as is found in glaciated regions in large areas of eastern north america or in portions of western north america the amplifications on rock sites can be in excess of 3 5 at high frequencies in contrast to the amplifications of less than 1 2 on very hard rock sites the consideration of unattenuated amplification alone is computationally convenient but what matters for ground motion estimation is the combined effect of amplification and attenuation for reasonable values of the attenuation parameter k 0 the combined effect of attenuation and amplification for rock sites peaks between about 2 and 5 hz with a maximum level of less than 1 8 the combined effect is about a factor of 1 5 at 1 hz and is less than unity for frequencies in the range of 10 to 20 hz depending on t using these amplifications we find provisional values of about ao 70 bars and k 0 0 035 sec for rock sites in western north america by fitting our empirically determined response spectra for an m 6 5 event to simulated values the borehole data yield shear velocities 033o of 618 and 306 rrdsec for rock and soil sites respectively when averaged over the upper 30 m from this we recommend that v30 equals 620 and 310 m sec for applications requiring the average velocity for rock and soil sites in western north america by combining the amplifications for rock sites and the site factors obtained from our analysis of strong motion data we derive amplifications for sites with 17 3o 520 m sec nehrp class c corresponding to a mix of rock and soil sites and v3o 310 and 255 m sec average soil and nehrp class d sites respectively for the average soil site the combined effect of amplification and attenuation exceeds a factor of 2 0 for frequencies between 0 4 and about 4 hz with a peak site effect of 2 4 the peak of the nehrp class d site effect is 2 7

a u pb age for the cambrian taylor formation antarctica implications for the cambrian time scale abstract isotopic ages for the middle cambrian late cambrian are few because formations of the appropriate age combining diagnostic fossils and rocks datable by precise isotopic techniques are not common the taylor formation in antarctica includes carbonate units that host trilobites indicating an early late middle cambrian age volcanics below and above the trilobite bearing horizon yielded zircons that date the horizon at documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcommand cyr renewcommand rmdefault wncyr renewcommand sfdefault wncyss renewcommand encodingdefault ot2 normalfont selectfont declaretextfontcommand textcyr cyr pagestyle empty declaremathsizes 10 9 7 6 begin document landscape 505 1 pm 1 3 end document ma this age suggests that

origin of the rheic ocean rifting along a neoproterozoic suture the rheic ocean is widely believed to have formed in the late cambrian early ordovician as a result of the drift of peri gondwanan terranes such as avalonia and carolina from the northern margin of gondwana and to have been consumed in the devonian carboniferous by continent continent collision during the formation of pangea other peri gondwanan terranes e g armorica ossa morena northwest iberia saxo thuringia moldanubia remained along the gondwanan margin at the time of rheic ocean formation differences in the neoproterozoic histories of these peri gondwanan terranes suggest the location of the rheic ocean rift may have been inherited from neoproterozoic lithospheric structures formed by the accretion and dispersal of peri gondwanan terranes along the northern gondwanan margin prior to rheic ocean opening avalonia and carolina have sm nd isotopic characteristics indicative of recycling of a juvenile ca 1 ga source and they were accreted to the northern gondwanan margin prior to voluminous late neoproterozoic arc magmatism in contrast sm nd isotopic characteristics of most other peri gondwanan terranes closely match those of eburnian basement suggesting they reflect recycling of ancient 2 ga west african crust the basements of terranes initially rifted from gondwana to form the rheic ocean were those that had previously accreted during neoproterozoic orogenesis suggesting the rift was located near the suture between the accreted terranes and cratonic northern gondwana opening of the rheic ocean coincided with the onset of subduction beneath the laurentian margin in its predecessor the iapetus ocean suggesting geodynamic linkages between the destruction of the iapetus ocean and the creation of the rheic ocean

the middle late cambrian reef transition and related geological events a review and new view abstract the reefs of the middle late cambrian cambrian epoch 3 furongian have long been simply considered as microbialites that flourished in the aftermath of the archaeocyath extinction thorough review of the reefs in these periods shows however that the cambrian epoch 3 and the furongian actually yield different types of reefs the cambrian epoch 3 reefs are dominated by thrombolites and dendrolites largely constructed by the calcified microbes epiphyton and renalcis on the other hand the furongian reefs consist mainly of maze like maceriate reefs and columnar stromatolites the maceriate reefs most likely formed by siliceous sponges and calcified microbes including girvanella and tarthinia whereas the columnar stromatolites were mainly constructed by girvanella tarthinia and minor siliceous sponges other microbial reefs e g non columnar stromatolites persisted during the cambrian epoch 3 and the furongian mainly as small patch reefs or reefal crusts lithistid sponge microbial reefs initially formed in the cambrian epoch 3 and occurred throughout the furongian but occupied only a minor portion during these periods several geological events occurred across the boundary between the cambrian epoch 3 and the furongian including positive carbon and sulfur isotope excursions a eustatic sea level drop major faunal turnover of trilobites and diversification of new organisms the coincidence of these events and the transition in reefal fabrics suggest that reef ecosystems were significantly influenced by at least some of these events among the events it is likely that sea level change would have affected reefs although further studies are required in order to test whether and how the other events influenced the reef transition epiphyton and renalcis and thrombolites and dendrolites formed by them declined greatly most likely due to sea level fall and thus decreased in shallow marine habitat at the end of cambrian epoch 3 the cambrian epoch 3 thrombolites and dendrolites were gradually replaced by a sponge microbial association of the maze like maceriate reefs and the columnar stromatolites in the furongian coincident with a sea level rise

ground motion prediction equations for eastern north america from a referenced empirical approach implications for epistemic uncertainty abstract i outline a referenced empirical approach to the development of ground motion prediction equations gmpes the technique is illustrated by using it to develop gmpes for eastern north america ena the approach combines the ena ground motion database with the empirical prediction equations of boore and atkinson 2008 for the reference region of western north america wna the referenced empirical approach provides gmpes for ena that are in agreement with regional ground motion observations while being constrained to follow the overall scaling behavior of ground motion that is observed in better instrumented active tectonic regions they are presented as an alternative to the commonly used stochastic ground motion relations for ena the motivation of the article is not to supplant stochastic gmpes but is rather to consider other approaches that might shed light on their epistemic uncertainty differences between the referenced empirical gmpes of this study and the stochastic gmpes of atkinson and boore 2006 along with inconsistencies between both of these studies and inferences based on intensity observations suggest that uncertainty in median enagmpes is about a factor of 1 5 2 for m 5 at distances from 10 to 70 km uncertainty is greater than a factor of 2 for large events m 7 at distances within 10 km of the source it may be that saturation effects not modeled in the stochastic predictions but inferred from observations in other regions cause overestimation of near source amplitudes from large events in atkinson and boore 2006 on the other hand these saturation effects cannot be directly verified in ena data differences in predictions according to the approach taken are also significant at distances from 40 to 150 km due to uncertainty in the shape of the attenuation function that will be realized in future earthquakes

birth of a volcanic passive margin in cambrian time rift paleogeography of the ossa morena zone sw spain abstract mapping at 1 10000 scale of both north n and south s flanks of the variscan monesterio antiform in the ossa morena zone southern spain in association with detailed petrographic and major element analyses of magmatic rocks has revealed the building of a passive but volcanically active oceanic margin in cambrian time this margin was located in northern gondwana and represents the beginning of an extensional tectonic regime that concluded with the opening of the rheic ocean at time of eruption middle cambrian the n flank was located on the northern coastline of a marine basin in the process of passive rifting the vents mainly located in its western part were subaerial continental and or shallow marine on the s flank eruptions and deposits were shallow marine occurring as lava flows and pillows interstratified within shallow marine sediments on both flanks intrusives were emplaced after the extrusives lateral thickness variations of the sedimentary deposits testify to the building during four distinct periods of a rifted passive margin with a shifting locus of volcanic activity over time the composition of magmas was bimodal the mafic magmas are silica saturated alkaline to sub alkaline and somewhat ti rich perhaps originating from partial melting of a subcontinental mantle that was less metasomatized with time the youngest magmatism with an affinity close to that of morb likely had an asthenospheric source the alkaline felsic products are diverse and may have originated from a very heterogeneous continental crust in each set partial melting relationships prevail suggesting that the melts rose along open fractures as soon as they formed in the context of lithospheric thinning it is possible that mantle and crustal melting was triggered by decoupling between rheologically different materials

new u pb ages for early ordovician magmatism in central spain felsic orthogneisses occur widely in the ollo de sapo domain of the central iberian zone most of which were previously considered to represent a precambrian basement to the palaeozoic sequences of this domain however new u pb dating across the berzosa riaza shear zone sierra de guadarrama central spain indicates an early ordovician age for the most representative types of orthogneisses in the eastern part of the ollo de sapo domain dated rocks include the volcaniclastic cardoso gneiss 480 2 ma from the low medium grade hanging wall the riaza gneiss 468 8 16 ma mylonitic granite in the berzosa riaza shear zone three types of leucogneiss buitrago gneiss 488 8 10 ma megacrystic granite 482 11 14 ma aplitic vein and 482 8 9 ma gneissic leucogranite and the la morcuera granitic augen gneiss 477 4 ma in the high grade footwall the new age of the cardoso gneiss brackets to the mid late arenig the so called early ordovician sardic unconformity characteristic of the central iberian zone these new ages suggest that the broadly coeval volcanism and plutonism were closely associated with the sardic events and that these orthogneisses were part of a felsic magmatic belt which extended along the ollo de sapo domain of the central iberian zone this magmatic belt is interpreted to have been active during the early ordovician break up of the peri gondwanan margin of the iapetus ocean

a proposed nomenclature for stages and series for the cambrian of laurentia an internally consistent succession of six named regional stages from youngest to oldest sunwaptan steptoean marjuman delamaran dyeran montezuman with their boundaries defined by regional extinction events within the trilobite record is proposed for the trilobite bearing rocks of laurentia sub trilobite stage s are recommended but unnamed the three youngest stages have been named previously but the lower boundary of the marjuman is shifted downward the three older stages within the trilobite record are new if deemed necessary four regional series are also suggested from youngest to oldest millardan lincolnian waucoban and begadean each of the three youngest series accommodates two stages

simulation of earthquake ground motions in the eastern united states using deterministic physics based and site based stochastic approaches abstract earthquake ground motion recordings are scarce in the central and eastern united states ceus for large magnitude events and at close distances we use two different simulation approaches a deterministic physics based method and a site based stochastic method to simulate ground motions over a wide range of magnitudes drawing on previous results for the modeling of recordings from the 2011 m w 5 8 mineral virginia earthquake and using the 2001 m w 7 6 bhuj india earthquake as a tectonic analog for a large magnitude ceus event we are able to calibrate the two simulation methods over this magnitude range both models show a good fit to the mineral and bhuj observations from 0 1 to 10 hz model parameters are then adjusted to obtain simulations for m w 6 5 7 0 and 7 6 events in the ceus our simulations are compared with the 2014 u s geological survey weighted combination of existing ground motion prediction equations in the ceus the physics based simulations show comparable response spectral amplitudes and a fairly similar attenuation with distance the site based stochastic simulations suggest a slightly faster attenuation of the response spectral amplitudes with distance for larger magnitude events and as a result slightly lower amplitudes at distances greater than 200 km both models are plausible alternatives and given the few available data points in the ceus can be used to represent the epistemic uncertainty in modeling of postulated ceus large magnitude events

representative seismic hazard map of coimbatore india the seismic hazard value of any region depends upon three important components such as probable earthquake location maximum earthquake magnitude and the attenuation equation this paper presents a representative way of estimating these three important components considering region specific seismotectonic features rupture based seismic hazard analysis rbsha given by anbazhagan et al 2011 is used to determine the probable future earthquake locations this approach is verified on the earthquake data of bhuj region the probable earthquake location for this region is identified considering earthquake data till the year 2000 these identified locations match well with the reported locations after 2000 the further coimbatore city is selected as the study area to develop a representative seismic hazard map using rbsha approach and to compare with deterministic seismic hazard analysis probable future earthquake zones for coimbatore are located considering the rupture phenomenon as per energy release theory discussed by anbazhagan et at 2011 rupture character of the region has been established by estimating the subsurface rupture length of each source and normalized with respect to the length of the source average rupture length of the source with respect to its total length is found to be similar for most of the sources in the region which is called as the rupture character of the region maximum magnitudes of probable zones are estimated considering seismic sources close by and regional rupture character established representative gmpes for the study area have been selected by carrying out efficacy test through an average log likelihood value llh as ranking estimator and considering the isoseismal map new seismic hazard map of coimbatore has been developed using the above regional representative parameters of probable earthquake locations maximum earthquake magnitude and best suitable gmpes the new hazard map gives acceleration values at bedrock for maximum possible earthquakes these results are compared with deterministic seismic hazard map and recently published probabilistic seismic hazard values c 2014 elsevier b v all rights reserved

a revision of ordovician series and stages from the historical type area this paper is a revision of the standard chronostratigraphy of the ordovician of the historical type area in england and wales the revision is a response to the need for more precise definitions of series and stages especially for practical international correlation in some cases this has entailed moving horizons for series bases away from those in the classical sections the scheme will be used as the standard for a forthcoming revision of the correlation chart of the british ordovician system the ordovician is divided into five series tremadoc arenig llanvirn caradoc and ashgill the llanvirn is extended to include part of the classical llandeilo series which is included within it as a stage where stage subdivisions of standard series have not yet been defined as in the tremadoc they are proposed in this paper however bancroft s fine stadial divisions of the caradoc which have been criticized for their brevity and local utility are combined into four new stages which will have wider application the former caradoc subdivisions are retained as substages for the purposes of regional correlation

intensity prediction equations for north america abstract equations that predict intensity as a function of magnitude and distance are useful tools for hazard and risk assessment and in interpretation of both contemporary and historical earthquake information the intensity prediction equations of atkinson and wald 2007 hereafter aw07 have been remarkably successful in describing the level and intensity of motions reported under the did you feel it dyfi program over the last several years examination of the performance of aw07 for north american earthquakes evaluated using an extensive compiled database of dyfi observations from 2000 to 2013 suggests that there is little statistical basis for revising these equations however a problem with the aw07 equations is that they predict unrealistically large median intensities for large events m 6 at close distances in this study we revise aw07 to improve the intensity scaling at large magnitudes and close distances by reconciling intensity equations with ground motion prediction equations

empirical attenuation of ground motion spectral amplitudes in southeastern canada and the northeastern united states a database of 1700 digital seismograms from 186 earthquakes of mag nitude mn 2 5 5 6 that occurred in southeastern canada and the northeastern united states from 1990 to 2003 was compiled maximum likelihood regression analysis of the database was performed to determine a model for the attenuation of fourier spectral amplitudes for the shear window for the vertical and horizontal component of motion for frequencies from 0 2 to 20 hz fourier amplitudes follow a hinged trilinear attenuation model fourier spectral amplitudes decay as r 1 3 where r is hypocentral distance within 70 km of the source there is a transition zone from 70 to 140 km as the direct waves are joined by strong postcritical reflections where the attenuation is described as r 0 2 spectral amplitudes actually increase with distance in this range for low frequencies beyond 140 km the attenuation is well described by r 0 5 corresponding to geometric spreading in two dimensions the associated model for the regional quality factor for frequencies greater than 1 hz can be ex pressed as q 893f 032 q can be better modeled over a wider frequency range 0 2 20 hz by a polynomial expression log q 3 052 0 393 log f 0 945 log f 2 0 327 log f 3 the polynomial expression accommodates the observation that q values are at a minimum about 1000 near 1 hz and rise at both lower and higher frequencies correction factors for the spectral amplitude model that describe the effects of focal depth on the amplitudes and their attenuation are developed using the subset of events with known focal depth the attenuation model is similar to that determined from an earlier study with more limited data atkinson and mereu 1992 but the enlarged database indicates more rapid near source amplitude decay and higher q the attenuation model is used to play back attenuation effects to determine the apparent source spectrum for each earthquake in the database and hence determine moment magnitude m and brune stress drop the events have moment magnitude in the range from 2 5 to 5 stress drop increases with moment magnitude for events of m 4 3 then appears to attain a relatively constant level in the range from 100 to 200 bars for the larger events as previously noted in atkinson 1993b the results of this study provide a useful framework for improving regional ground motion relations in eastern north america they further our understanding of attenuation in the region through analysis of an enlarged ground motion database in particular the inclusion of the three component broadband data gathered over the last decade allows extension of attenuation models to both horizontal and vertical components over a broad frequency range 0 2 20 hz

ground motion models for seismic hazard assessment in western iberia constraints from instrumental data and intensity observations abstract the lack of constraints regarding ground motion propagation characteristics in western iberia remains one of the major hindrances to accurate seismic hazard and seismic risk assessment in the region the fact that western iberia is geographically located near the confluence of oceanic crust active continental crust and stable continental crust further complicates the selection of appropriate ground motion models to address this question we compare through visual inspection and residual analysis the regional ground motion data for moderate magnitude earthquakes with a set of six ground motion prediction equations some of which were developed for active tectonic regions and the others for stable continental regions although the available data pertain mostly to offshore moderate magnitude earthquakes m 4 8 6 0 at large distances 100 400 km the few records from an onshore m 4 0 earthquake and from the 1969 m 7 8 earthquake display similar trends the results show that the performance of the models is period dependent with shorter spectral periods 0 01 s 0 1 s 0 2 s and 0 5 s being strongly underpredicted by models developed for shallow active tectonic regions more interestingly the performance of the models for stable continental regions seems to be magnitude dependent with response spectra amplitudes for magnitudes of engineering interest being accurately estimated by the models the inspection of the residual distributions of intensity observations leads to similar conclusions for the offshore data while highlighting the extent of epistemic uncertainty in predicting the ground motions for moderate magnitude earthquakes at short to moderate distances

in situ u pb zircon ages for early ordovician magmatism in the eastern pyrenees france the canigou orthogneisses u pb age determinations with an ion probe on zircons within orthogneisses from the canigou massif eastern pyrenees give an emplacement age for their granitic protolith of 475 10 ma arenigian this invalidates the previous interpretation of basement cover relationships between the orthogneisses and the overlying lower cambrian canaveilles metasedimentary series and corroborates the intrusive character of the orthogneisses which is further supported by field evidence the data also define two groups of inherited zircons paleo meso proterozoic and cadomian in addition to partial lead loss during the hercynian late carboniferous high temperature low pressure metamorphic event these results are in agreement with ages reported from other orthogneissic bodies across the entire variscan chain of western europe and indicate the existence of a widespread cambro ordovician magmatic event

the recommended cambrian ordovician global boundary stratotype of the xiaoyangqiao section dayangcha jilin province china this paper provides a brief outline of the current detailed inter disciplinary work on the xiaoyangquiao section trying to expose all the aspects for reference tied to the global single stratigraphic point gssp concept for defining the cambrian ordovician boundary the 45 m critical interval of this section outcrops very well along the steep bank of a stream and is free from folding faulting intrusions and has not been affected by weathering colour alternation of conodonts and acritarchs and crystallinity indices of illite all indicate a maximum thermal grade of 100 c the lithofacies being of great lateral persistence for a hundred kilometres consists mainly of a rhythmical sequence of lime mudstone and shales deposited in a moderately deep outer shelf environment of quiet water well below the normal storm wave base chemical investigation of the rocks demonstrates strong positive correlation between a12o3 content and those of k2o mgo fe2o3 tio2 be cr co ni zn and ba indicating these components are tied to the clay fractions a stable depositional environment is demonstrated by the uniform chemistries through the boundary interval close to the boundary itself p2o5 contents are low indicating continuous sedimentation at fairly substantial rates the major biological events the biostratigraphic framework and the stratigraphic range of conodont graptolite trilobite and acritarch taxa are illustrated briefly with diagrams following the majority views of the calgary plenary session the boundary level is to be chosen at a point marked by the first appearance datum fad of the selected conodont taxon or taxa in the vicinity of the level close to but below the first influx of nematophorous graptolites the following four points marked by the incoming of conodont taxon or taxa are recommended for consideration of the golden spike 1 fad of cordylodus intermedius at 5 28 m below the first influx of nematophorous graptolites 2 fad of hirsutodontus simpler cordylodus drucei albiconus postcostatus at 5 23 m 3 fad of semiacontiodus lavadamensis utahconus utahensis monocostodus sevierensis at 3 85 m 4 fad of cordylodus lindstromi at 2 23 m for the following reasons the fad of h simplex c drucei a postcostatus is favoured 1 the taxa are all distinct and widely dispersed 2 intensive evolutionary change took place in conodonts graptolites trilobites and acritarchs prior to or after this point all the fossil groups occur together providing correlation with many regions throughout the world 3 the point is in a position between the previously widely accepted boundary levels based on graptolites and trilobites 4 the proposed point lies within a thin laterally persistent rhythmical sequence the fad of cordylodus lindstromi is also a favourable point sharing many advantages mentioned above but this point is less satisfactory in being defined by the fad of a single taxon c lindstromi which also has an extremely small population size an isochron age of 500 7 7 4 ma is determined from clay fractions of mudstones 8 5 m below the proposed point by means of the rubidium strontium method the nd signature determined from conodonts trilobites hyolithids and acrotretid brachiopods has a mean value of 6 7 comparable with that of the coeval oceanic water mass occupying southeastern north america and europe and indicating that northeastern china bordered the same ocean the mean tdm model age determined was 1 26 ga at the time of sedimentation compatible with the mean tdm model age of approximately 1 1 ga for the pacific ocean today the relatively low value of the tdm model age indicates a substantial input from young orogenic volcanic island arcs and terranes

a κ model for mainland france an important parameter for the characterization of strong ground motion at high frequencies 1 hz is kappa which models a linear decay of the acceleration spectrum a f in log linear space i e a f a 0 exp f for f f e where f is frequency f e is a low frequency limit and a 0 controls the amplitude of the spectrum is a key input parameter in the stochastic method for the simulation of strong ground motion which is particularly useful for areas with insufficient strong motion data to enable the derivation of robust empirical ground motion prediction equations such as mainland france numerous studies using strong motion data from western north america wna an active tectonic region where surface rock is predominantly soft and eastern north america ena a stable continental region where surface rock is predominantly very hard have demonstrated that varies with region and surface geology with wna rock sites having a of about 0 04 s and ena rock sites having a of about 0 006 s lower s are one reason why high frequency strong ground motions in stable regions are generally higher than in active regions for the same magnitude and distance few if any estimates of s for french sites have been published therefore the purpose of this study is to estimate using data recorded by the french national strong motion network rap for various sites in different regions of mainland france for each record a value of is estimated by following the procedure developed by anderson and hough bull seismol soc am 74 1969 1993 1984 this method is based on the analysis of the s wave spectrum which has to be performed manually thus leading to some uncertainties for the three french regions where most records are available the pyrenees the alps and the cotes d azur a regional model is developed using weighted regression on the local geology soil or rock and source to site distance it is found that the studied regions have a mean between the values found for wna and ena for example for the alps region a value of 0 0254 s is found for rock sites an estimate reasonably consistent with previous studies

evaluation of ground motion models for usgs seismic hazard forecasts induced and tectonic earthquakes in the central and eastern united statesevaluation of gmms for usgs seismic hazard forecasts

modifications to existing ground motion prediction equations in light of new data we compare our recent ground motion prediction equations gmpes for western north america wna boore and atkinson 2008 ba08 and eastern north america ena atkinson and boore 2006 ab06 atkinson 2008 a08 to newly available ground motion data based on these comparisons we suggest revisions to our gmpes for both wna and ena the revisions for wna affect only those events with m 5 75 while those for ena affect all magnitudes these are simple modi fications to the existing gmpes that bring them into significantly better agreement with data the wealth of new data clearly demonstrates that these modifications are warranted we therefore recommend the use of the updated equations for seismic hazard analyses and other applications more detailed studies are under way by many investigators including ourselves to develop a new generation of ground motion models in both wna and ena from scratch through a comprehensive reevaluation of source path site and modeling issues in time those more complete models will replace those proposed in this study however as the new models will be several years in development we recommend using the modified models proposed herein labeled ba08 for wna ab06 for ena and a08 for ena to replace a08 as interim updates to our existing models the proposed models are in demonstrable agreement with a rich database of ground motions for moderate magnitude earthquakes in both wna and ena and are constrained at larger magnitudes by the ba08 magnitude and distance scaling

earthquake source spectra in eastern north america source spectra for earthquakes of 3 m 7 in eastern north america ena are determined from regional seismograph recordings strong motion records teleseismic data and modified mercalli intensity data the inclusion of mmi data is made possible by the finding that the felt area of an earthquake is an accurate measure of its high frequency spectral level at the source current ground motion relations for ena are based on a brune source model with a stress parameter of 100 bars this model is a poor fit to ena source spectra for events of m 4 at high frequencies 5 to 10 hz observed spectral amplitudes are more nearly matched by a brune stress parameter of 200 bars intermediate frequency amplitudes near 1 hz are matched by a stress parameter of approximately 50 bars an empirical two corner source model is proposed to describe ena source spectra for events of 4 m 7

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

seismic hazard map of southeast missouri and likely magnitude of the february 1812 new madrid earthquake abstract the new madrid seismic zone lies beneath the upper mississippi embayment straddling the border between southeastern missouri and northwestern tennessee in late 1811 and early 1812 it produced five earthquakes of magnitudes 6 5 violently shaking the central and eastern united states ceus its magnitude and recurrence are of concern to today s central united states regions by considering the effects of local geology deterministic scenario maps m w 7 3 and 7 7 were produced for ground motions intended to simulate the 7 february 1812 event nm3 which was the largest felt these maps include spatial estimates of peak ground acceleration and of 0 2 s and 1 0 s spectral acceleration sa compared with the isoseismic map of modified mercalli intensities mmis in southeast missouri the mmis converted from 0 2 s sa suggest that m w 7 7 is a plausible scenario for nm3 to better constrain its magnitude other ceus sites shaken during nm3 were also examined local site conditions were studied and evaluated before calculating the threshold magnitude for the reported mmis these results indicate that the magnitude of nm3 was at least m w 7 6 which validates our estimated size of m w 7 7 for southeastern missouri

ground motion amplitudes for earthquakes in puerto rico we explore ground motion amplitudes for earthquakes in puerto rico using the referenced empirical approach the technique is based on the use of residual analysis to model discrepancies between ground motion observations for puerto rico and a reference ground motion prediction equation gmpe the refer ence gmpe is that of boore and atkinson 2008 for shallow crustal earthquakes in active tectonic regions as modified by atkinson and boore 2011 to improve the fit for small to moderate events amplitudes are examined for both shallow depth 34 km and deep 35 200 km earthquakes in puerto rico overall we conclude that ground motions in puerto rico are consistent in attenuation rates with those in other active regions for shallow events amplitude levels appear to be lower than those predicted by boore and atkinson 2008 but the discrepancy is magnitude dependent decreasing to a near zero bias near m 6 we thus postulate that amplitude levels may be considered equivalent for the magnitude distance range of engineering interest allowing gmpes for other active regions to be used for puerto rico furthermore deeper events have amplitudes that also appear consistent with typical gmpes for shallow events if the greater distance of the events due to their depth is considered

cambrian palaeomagnetic data from baltica implications for true polar wander and cambrian palaeogeography a reliable early cambrian c 535 ma and a preliminary late cambrian c 500 ma palaeomagnetic pole from baltica sweden overlap within uncertainty and they are also broadly compatible with vendian c 583 ma palaeomagnetic data apparent polar wander for baltica amounts to less than 25 between 583 and 500 ma and therefore negates recent speculations that the earth tipped 90 during the early cambrian true polar wander throughout vendian and cambrian times baltica lay at southerly latitudes c 30 60 s baltica was geographically inverted and present day northern baltica faced the nw margin of gondwana which covered the south pole laurentia eastern baltica and laurentia west gondwana were separated by the iapetus ocean while the aegir sea separated western baltica from the taimyr region of siberia during the cambrian baltica probably moved eastward along the gondwana margin and by c 515 520 ma subduction in the aegir sea was initiated a major event is recognized in late cambrian or early ordovician times c 500 478 ma when baltica must have undergone a 55 counter clockwise rotation in c 22 million years 3 ma we relate this to the early caledonian finnmarkian orogeny which involved arc continent collision following subduction

relative sea level changes in baltoscandia in the cumbrian and early ordovician the predominance of tectonic factors and the absence of large scale eustatic fluctuations abstract fluctuations in sea depth within a magnitude 20 100 m and a duration of 1 10 m y are often explained by rapid eustatic changes so called third order eustatic events considerable influence of regional tectonics on relative sea level changes has been demonstrated by many authors but because of uncertainties in the timing of short events in widely separated regions the problem of separating tectonic and eustatic factors still remains unsolved in this paper a new and simple approach is used to reveal the presence or absence of eustatic events we consider the st petersburg area and north estonia in the north eastern region of the east baltic from the late early cambrian until the middle of the tremadoc early ordovician deposition was extremely slow and the sea bed remained for a long time in a well defined peritidal zone in a water depth 10 m under such environmental conditions a sea level rise of 10 m would result in marked changes in the character of faunas and sedimentation in the time interval considered here significant sea deepening in the north eastern baltic region occurred only twice and its magnitude did not exceed 10 20 m a fall of sea level by 10 m would result in complete regression in the peritidal zone this situation also occurred in region however the preservation of a sequence of unconsolidated sands which is only a few tens of metres thick and includes all the main stratigraphic subdivisions on a regional scale indicates that the crustal surface reached a very low altitude 10 20 m above sea level these data show that in the late late cambrian to the middle of the tremadoc over a period of 40 m y long eustatic sea level changes did not exceed 10 20 m this limits the magnitude of several third order cycles eustatic events with duration of a few million years which have been proposed previously for the epoch of the transition from the cambrian to the ordovician in the late early cambrian to the late cambrian transgressions and regressions with a magnitude of 50 150 m took place in southern sweden and lithuania since these phenomena occurred when there were no comparable eustatic sea level changes they must be associated with regional tectonic movements some were rapid and could be easily misinterpreted as indications of third order eustatic changes it is probable that some of the other eustatic events that have been proposed for the phanerozoic were actually not of eustatic but of tectonic origin such rapid tectonic movements with magnitude of 50 100 m in cratonic areas can be caused by changes in the forces in the lithospheric layer with a laterally variable thickness and by phase transitions in the mafic lower crust depending on the spatial distribution of vertical crustal movements both these mechanisms could have been operating in the east baltic and southern sweden in the cambrian

cambrian ordovician boundary age and duration of the lowest ordovician tremadoc series based on u pb zircon dates from avalonian wales two thin volcaniclastic sandstone beds in the bryn llin fawr road section in north wales overlie an apparent sequence boundary within the uppermost cambrian acerocare zone and are overlain by lowest ordovician lower tremadoc rhabdinopora faunas u pb geochronology of zircons from these sandstones yields a maximum cambrian ordovician boundary age of 489 0 6 ma this age indicates both that the tremadoc series lowest ordovician may be shorter in duration than was previously thought and that the duration of the middle and late cambrian c 22 ma was much less than that of the early cambrian c 33 ma cambrian trilobite zones locally had an average duration as short as 1 ma

carbon isotope stratigraphy of upper cambrian steptoean stage sequences of the eastern great basin record of a global oceanographic event a large global positive excursion in 13 c from 0 5 to 4 5 during the late cambrian pterocephaliid biomere steptoean stage aphelaspis elvinia zones is documented at high stratigraphic resolution in three sections in the eastern great basin the excursion which we refer to as the steptoean positive carbon isotope excursion or spice excursion began coincident with a world wide extinction event the 13 c data from the great basin reflect global seawater values in a wide range of lithologies including oolitic grainstones wackestones thrombolitic boundstones and flat pebble conglomerates we use a section at shingle pass in the southern egan range to divide the pterocephaliid biomere into eight isotope steps that represent equal divisions of the 13 c rise and fall 4 this provides a basis for recognition of a revised chronostratigraphic framework for the pterocephaliid biomere steptoean stage strata deposited during the beginning of the spice excursion record a major change in the pattern of sedimentation in the eastern great basin this is reflected in a siliciclastic carbonate transition at shingle pass nevada and a carbonate siliciclastic transition at the house range and lawson cove sections in utah a regional siliciclastic influx recognized throughout the great basin occurs near the peak of the spice excursion carbon isotope analyses from cratonal sections in wyoming provide independent evidence that a major sedimentary hiatus took place on the craton during the time of the spice excursion the correlated changes in 13 c relative sea level and the marine biota during the spice excursion provide remarkably detailed records of a major paleoceanographic event we speculate that changes in sea level climate or tectonics may have triggered the spice excursion and coeval extinction event subsequent burial of organic carbon caused the increase in 13 c and may have led to an interval of global cooling the results of this study lend confidence to carbon isotopic studies of pre mesozoic rocks

phreatomagmatic volcanism during the ordovician of the cantabrian mountains nw spain in the barrios formation of the southern cantabrian mountains pyroclastic rocks occur which have an ordovician age they form the filling of several craters and pipes which are unconformably overlain by ordovician respectively silurian sediments the pyroclastic material mainly consists of fractured quartz grains which are mixed with angular hydrothermally altered glas lapilli the strong fragmentation of the volcanoclastic components even in the lower parts of the pipes is caused by phreatomagmatic eruptions under shallow marine conditions the barrios formation which is disrupted by the volcanic necks was deposited in a shallow marine environment with a very low sedimentation rate

age determination of ordovician magmatism in ne sardinia and its bearing on variscan basement evolution a newly discovered pre variscan cover basement relationship in ne sardinia is defined by differences in structural and metamorphic histories the oldest metamorphic fabrics in the basement are absent from a series of metaplutons that are inferred to be comagmatic with metavolcanic rocks in the cover cover and basement are further distinguished by contrasting metapelite compositions superimposed metamorphism is represented by pre variscan garnet and variscan plagioclase porphyroblasts that appear in the field as a mixed garnet albite zone in situ u pb zircon dating of meta igneous rocks from cover and basement by laser ablation inductively coupled plasma mass spectrometry gives ages of 458 7 ma for the tanaunella orthogneiss 456 14 ma for the lode orthogneiss and 474 13 ma for the lula porphyroid the internal sardinian variscides thus incorporate a mid ordovician magmatic belt developed upon an older basement correlation is proposed with a tectonostratigraphic domain that is at present exposed in the alps within the mid ordovician peri gondwanan realm the internal sardinian variscides appear to have developed along an active margin whereas the foreland correlates with the ibero aquitaine domain and is related to the evolution of a passive margin during rifting and detachment of avalonia to form the rheic ocean

field based accounting of co2 sequestration in ultramafic mine wastes using portable x ray diffraction carbon mineralization the sequestration of carbon within minerals presents one method through which we could control rising levels of anthropogenic carbon dioxide co emissions the mineral wastes produced by some ultramafic hosted mines have the ability to sequester atmospheric co via passive carbonation reactions carbon accounting in mine tailings is typically performed using laboratory based quantitative x ray diffraction xrd or thermogravimetric methods which are used to measure the abundances of carbonate bearing minerals such as hydromagnesite mg co oh 4ho and pyroaurite mg fe23 text fe 3 2 co oh 4ho the recent development of portable xrd instruments now allows for the characterization and quantification of minerals in the field here we assess the feasibility of using a portable xrd instrument for field based carbon accounting in tailings from the woodsreef chrysotile mine new south wales australia modal mineralogy was obtained by rietveld refinements of data collected with an inxitu terra portable xrd the partial or no known crystal structures ponkcs method was used to account for turbostratic stacking disorder in serpentine minerals which are the dominant phases in tailings from woodsreef weighed mixtures of synthetic tailings were made to evaluate the precision and accuracy of quantitative phase analysis using the portable instrument an average absolute deviation bias of 8 2 wt from the actual composition of the synthetic tailings was found using the portable instrument this is comparable to the bias obtained using a laboratory based diffractometer 9 6 wt absolute and to the results from previous quantitative xrd studies involving serpentine minerals the methodology developed using the synthetic tailings was then applied to natural tailings samples from woodsreef surface crusts forming on the tailings pile were found to contain hydromagnesite 5 8 wt and pyroaurite 2 1 wt comparable results were obtained using the laboratory based instrument and these results are expected to have similar biases to the analyses of the synthetic tailings these findings demonstrate that portable xrd instruments may be used for field based measurement of carbon sequestration in minerals in engineered and natural environments

early cambrian continental reconstructions climatically related sedimentary facies and faunal distributions have been combined with palaeomagnetic data to make provisional reconstructions of the early cambrian world laurentia baltica and siberia appear to have formed a continental group which rifted apart from each other prior to 600 ma the consolidation of much of gondwana probably occurred in the pan african orogeny well before the cambrian though the assembly of several east asian terranes is still speculative the archaeocyathan reefs of siberia southern europe and morocco with their bigotinid trilobite fauna suggest that these areas were adjacent to each other and at low latitudes avalonia had close faunal links with western gondwana but lacked bigotinids and archaeocyathans and may have been situated off west africa and florida during the early cambrian there was a northward migration of laurentia towards the equator as its separation from baltica and siberia increased and a southward movement of gondwana

ordovician palaeogeography with new palaeomagnetic data from the montagne noire southern france a joint palaeomagnetic and ar 40 ar 39 study has been performed on two olistolithic blocks from the cabrieres wildflysch in the montagne noire region of the massif central in france there andesitic volcanic and volcaniclastic rocks of llanvirn early caradoc age ca 470 458 ma occur despite extensive secondary alteration destruction of the dominant magnetic mineral phase and ar 40 ar 39 whole rock experiments that demonstrate that the volcanic rocks suffered significant argon loss a positive fold test and the presence of dual polarities suggest that a primary ordovician magnetisation has mostly survived this is one of the few documented cases where the argon system was substantially reset whilst a subordinate set of small relatively unaltered magnetite grains probably hosted in silicates still carry the original in this case ordovician remanence the new data show that the montagne noire region was located at high southerly latitudes 68degrees 19 15 during the mid ordovician this latitude represents the location for nw gondwana of which the massif central was a part palaeomagnetic data from all the central european massifs and terranes demonstrate a close link to the gondwana margin during the lower and middle ordovician

alternative hybrid empirical ground motion model for central and eastern north america using hybrid simulations and nga west2 models abstract an alternative hybrid empirical ground motion model for central and eastern north america cena is proposed the new ground motion model gmm is developed for the average horizontal components rotd50 of peak ground acceleration peak ground velocity and 5 damped pseudospectral accelerations at 0 01 10 s spectral periods hybrid empirical estimates are derived using the regional modification factors between two regions host and target along with empirical gmms from the host region the regional adjustment factors are ratios of the intensity measures from the generated synthetics in the host western north america wna and target cena regions in this study the recent updated empirical gmms developed by the pacific earthquake engineering research center for the next generation attenuation west2 nga west2 project bozorgnia et al 2014 are incorporated we used a broadband simulation technique proposed by the authors shahjouei and pezeshk 2015a to generate synthetics for both the wna and cena regions in which the high frequency and low frequency parts of synthetics are calculated through a stochastic finite fault method and kinematic source models along with the deterministic wave propagation respectively the updated seismological and geological parameters are deployed in simulations the new ground motion model is developed as part of the nga east research project considering multiple shaking scenarios that characterize the magnitude in the m 5 0 8 0 range the proposed gmm represents the level of ground shaking in the distance range of 2 1000 km and are developed for the reference rock site condition with v s 30 3 km s in cena the results are compared with some other existing models in the region in addition a comprehensive residual analysis is performed using the recorded earthquakes available in the nga east database

new uppermost cambrian u pb date from avalonian wales and age of the cambrian ordovician boundary a crystal rich volcaniclastic sandstone in the lower peltura scarabaeoideszone at ogof ddu near criccieth north wales yields a u pb zircon age of 491 1 ma this late late cambrian date indicates a remarkably young age for the cambrian ordovician boundary whose age must be less than 491 ma hence the revised duration of the post placentian trilobite bearing cambrian indicates that local trilobite zonations allow a biostratigraphic resolution comparable to that provided by ordovician graptolites and mesozoic ammonites

ground motion prediction equations for hawaii from a referenced empirical approach ground motion prediction equations gmpes for hawaii are developed using the referenced empirical approach the technique is based on the use of residual analysis that models discrepancies between ground motion observations for hawaii and a reference gmpe in this case the gmpe of boore and atkinson 2008 for shallow crustal earthquakes in active tectonic regions the referenced empirical approach provides gmpes for hawaii that are in agreement with regional ground motion observations while being constrained to follow the overall scaling behavior of ground motion that is observed in better instrumented regions gmpes are developed for both shallow depth 20 km and deep 35 to 40 km earthquakes in hawaii

early paleozoic avalon gondwana unity an obituary response to palaeontological evidence bearing on global ordovician silurian continental reconstructions by r a fortey and l r m cocks

trilobite diversity patterns in the middle cambrian of southwestern europe a comparative study abstract this paper describes the pattern of trilobite diversity throughout the middle cambrian in two fossiliferous basins of the western gondwana margin the iberian chains northeastern spain and the montagne noire southern france the documented fluctuations of species diversity allow us to recognize 1 a substantial extinction event recorded in latest early cambrian times named valdemiedes event which separates the culmination of a widespread decline of trilobites and the stepwise immigration of cosmopolitan invaders 2 a major trilobite radiation occurring in the earliest leonian and culminating across the caesaraugustian languedocian transition in which a peak in diversity of trilobites and carpoids was close to a major flooding surface 3 a major reduction of trilobite taxa across the early middle languedocian transition related to a well documented regressional trend and 4 a second immigration of trilobite fauna in the late languedocian which coincided with trangressional pulses and the establishment of suitable shaly substrates in addition we summarize the known trilobite occurrences from the middle cambrian of southwestern europe maps of the distribution of some relevant taxa genera and species over the western gondwana margin are documented

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

a review of the late cambrian furongian palaeogeography in the western mediterranean region nw gondwana abstract the cambrian ordovician transition of the western mediterranean region nw gondwana is characterized by the record of major erosive unconformities with gaps that range from a chronostratigraphic stage to a series the hiatii are diachronous and involved progressively younger strata along the gondwanan margin from sw morocco to ne montagne noire they can be related to development of a multi stage rifting further north currently connected to the opening of the rheic ocean and concomitant erosion on southern rift shoulders the platforms of this margin of gondwana occupied temperate water mid latitudes and were dominated by siliciclastic sedimentation while carbonate factories were only episodically active in the montagne noire platform the upper cambrian is devoid of significant gaps in the southern montagne noire and the iberian chains there the sedimentation took place in a transgressive dominated depositional system with common offshore deposits and clayey substrates and was bracketed by two major regressive trends the late cambrian is also associated with the record of volcanic activity e g in the cantabrian and ossa morena zones and the northern montagne noire and widespread development of a tectonic instability that led to the episodic establishment of palaeotopographies and record of slope related facies associations several immigration events are recognized throughout the latest middle cambrian late cambrian and tremadocian the trilobites show a stepwise replacement of acado baltic type families e g the conocoryphid paradoxidid solenopleurid assemblage characterized by i a late languedocian latest middle cambrian co occurrence of middle cambrian trilobite families with the first anomocarid dorypygid and proasaphiscid invaders ii a late cambrian immigration replacing previous faunas composed of trilobites aphelaspidids catillicephalids ceratopygids damesellids eulomids idahoiids linchakephalids lisariids onchonotinids and pagodiids linguliformean brachiopods acrotretids obolids scaphelasmatids siphonotretids and zhanatellids echinoderms mitrates glyptocystitid cystoids and stromatocystoids and conodonts belonging to the lower peltura zone and iii the subsequent input of new trilobites asaphids calymenids catillicephalids nileids and remopleurids which marks the base of the proteuloma geinitzi zone associated with pelmatozoan holdfasts oryctoconus and a distinct input of late tremadocian conodonts paltodus deltifer zone the biogeographic distribution of latest middle and late cambrian trilobites supports brachiopod data indicating strong affinities between the western mediterranean region east gondwana north china korea south china australia and antarctica and kazakhstania during the late languedocian which became significantly stronger during the late cambrian this major shift may suggest modification in oceanic circulation patterns throughout gondwana across the middle late cambrian transition

effects of seismicity models and new ground motion prediction equations on seismic hazard assessment for four canadian cities seismicityratesandground motionpredictionequations gmpes arethe key uncertainties in probabilistic seismic hazard analysis psha we explore the impact of new findings and knowledge from seismological and ground motion studies on seismic hazard assessment for eastern and western canada updated information includes the reevaluation of seismicity rates and their interpretation in terms of seismic source zones and the use of new gmpes we refer to our model as an interim updated seismic hazard model as it does not treat all uncertainties comprehensively rather we address the impact of key uncertainties based on our updated interim seismic hazard model uniform hazard spectra uhs at four major cities across canada are obtained and compared with uhs in the current seismic hazard maps of canada 2005 2010 whicharebasedona1995seismichazardmodeldevelopedbythegeologicalsurveyof canada sensitivity analysis highlights the significant impact of seismicity smoothing in low to moderate seismic regions eastern canada while gmpes are important for all regions moreover our interim updated seismic hazard model can readily produce seismic hazard curves as well as seismic hazard deaggregation results for various site conditionsandformultipleprobabilitylevels thiscapabilityisessentialforcarryingout advanced earthquake engineering analyses

a global carbon isotope excursion spice during the late cambrian relation to trilobite extinctions organic matter burial and sea level abstract the steptoean positive carbon isotope excursion spice marks a global oceanographic event that confirms intercontinental correlations between different biogeographic realms based on agnostids and other blue water trilobites the spice excursion is documented from sections in laurentia kazakhstan china and australia where it begins with the mass extinction at the base of the pterocephaliid biomere steptoean stage in laurentia and at coeval extinction horizons in gondwana and perigondwana terranes the peak of spice 5 coincided with a time of maximum regression in laurentia spice is similar in this regard to excursions that coincide with glacio eustatic falls such as in the late ordovician a plausible scenario involves the transformation of ocean circulation between two states which led to enhanced coastal upwelling and benthic extinctions the lack of evidence for glaciation indicates that the coeval sea level fall sauk ii sauk iii event resulted from tectonic or hydrologic changes that remain poorly understood at this time

rifting during separation of eastern avalonia from gondwana evidence from subsidence analysis subsidence curves for cambrian ordovician sequences from the anglo welsh segment of the paleocontinent of avalonia reveal two periods of regionally enhanced basement subsidence early cambrian 545 518 ma and late cambrian to early tremadocian 505 490 ma the earlier event may record transtension following the avalonian cadomian orogeny the second event may be a transtensional precursor to the late tremadocian volcanic arc on eastern avalonia however paleomagnetic faunal volcanic and sedimentary evidence suggests that the main separation of eastern avalonia from gondwana occurred after middle arenigian time rifting during separation is probably recorded by localized middle arenigian to llanvirnian 480 462 ma subsidence along the welsh basin margin but rifting must have occurred mainly on the now obscured southern margin of the avalonian continent pronounced caradocian 462 449 ma subsidence is associated with back arc rifting after separation from gondwana