new evidence of a herd of titanosauriform sauropods from the lower berriasian of the iberian range spain abstract a study of the undescribed part of the las cerradicas tracksite in galve teruel spain has revealed 6 trackways made by small sauropods showing gregarious behaviour parallel trackways las cerradicas is located towards the top of the villar del arzobispo formation early berriasian the wide gauge condition the manus pes distance the kidney shaped morphology of the manus and the subtriangular morphology of the pes with a big digit i that swells medially and a narrow heel oriented posterolaterally suggest that the sauropods in question are more similar to sauropodichnus giganteus than to any other sauropod ichnotaxa some of the features point to the titanosauriforms as the best candidates to be the trackmakers recent work in bone histology the differences with respect to other iberian tracksites of similar age and the differences with respect to other sauropod herds of the track record do not allow us to establish whether the sauropods were juvenile or dwarfs the sauropod skeletal record and other large sauropod footprints in the villar del arzobispo formation could tip the scales in favour of the first hypothesis

meridional and downward propagation of atmospheric circulation anomalies part ii southern hemisphere cold season variability abstract as in the northern hemisphere there exists a simultaneous poleward propagation of temperature anomalies in the stratosphere and equatorward propagation in the troposphere in the southern hemisphere s cold season it takes about 110 days for anomalies of one polarity to propagate from the equator to the pole or half the period of the complete cycle nearly twice as long as in the northern hemisphere the earlier poleward propagation of temperature anomalies in upper levels compared with those in lower levels results in an apparent downward propagation in the stratosphere accompanying the poleward and downward propagating warm cold anomalies is a successive leveling steepening of isentropic surfaces reflecting a simultaneous reduction strengthening of the meridional temperature gradient and increase decrease of the vertical static stability following changes in the thermal fields are poleward and downward propagating zonal wind anomalies of the opposite sign the arrival of the pole

downward coupling between the stratosphere and troposphere the relative roles of wave and zonal mean processes abstract wave and zonal mean features of the downward dynamic coupling between the stratosphere and troposphere are compared by applying a time lagged singular value decomposition analysis to northern hemisphere height fields decomposed into zonal mean and its deviations it is found that both zonal and wave components contribute to the downward interaction with zonal wave 1 due to reflection dominating on the short time scale up to 12 days and the zonal mean due to wave mean flow interaction dominating on the longer time scale it is further shown that the two processes dominate during different years depending on the state of the stratosphere winters characterized by a basic state that is reflective for wave 1 show a strong relationship between stratospheric and tropospheric wave 1 fields when the stratosphere is leading and show no significant correlations in the zonal mean fields on the other hand winters characterized by a stratospheric state that does not reflect waves show a strong relat

stability of earthquake moment tensor inversions effect of the double couple constraint abstract we show that spurious large non double couple components can be obtained in inversions for the full deviatoric moment tensor for shallow crustal earthquakes due to inaccurate earth models the traditional best double couple solution does not in general provide an optimal estimate of a double couple mechanism and is only reliable when the non double couple component of the full deviatoric solution is small the inverse problem for the moment tensors of the 1998 antarctic plate and 2000 wharton basin strike slip earthquakes is shown in each case to have two well fitting minima in the misfit function of pure double couple solutions such pairs of solutions are most likely to exist for earthquakes which are close either to vertical strike slip or to dip slip on a fault plane dipping at 45 it is shown theoretically that these pairs of solutions arise from the combination of the pure double couple constraint and the instability of two elements of the moment tensor no significant non double couple component is found for the shallow thrusting 1996 biak indonesia earthquake

changes in occurrence of cold surges over east asia in association with arctic oscillation 1 it has been newly found that the occurrence of cold surges in east asia is significantly influenced by the arctic oscillation ao in the present study the events of cold surge are objectively determined based on several synoptic criteria and the phase dependency of its occurrences in association with the ao has been revealed during the negative ao phase the frequency of cold surge occurrence is relatively increased than that of neutral and positive ao phases the variation of upper level trough and jet stream over east asia and the siberian high in association of ao are suggested to explain the change of cold surge occurrences

toward understanding subtle instrumentation effects associated with weak seismic events in the near field abstract broadband observations of small earthquakes at short epicentral distances reveal a mixture of near field effects and instrumental artifacts we investigated these phenomena at a station equipped with an sts 2 and cmg 40t sensor situated almost above shallow m 3 0 to 3 8 events peak ground acceleration 2 10 1 m sec 2 the horizontal components were systematically accompanied by tiltlike disturbances and the tilt obtained from the sts 2 records exceeded more than 10 times the values predicted by the source model we also observed a so far uncommonly recognized type of disturbance whose shape is the first derivative of the tiltlike disturbance the most likely explanation seems to be clipping of high frequency signal peaks within the sensor system a computational model of a broadband feedback velocimeter as a linear dynamic system with saturation proved this interpretation on a qualitative level generally any asymmetry in the transfer of high frequencies in the feedback velocimeter would produce a long period disturbance of this type users of near fault broadband velocigrams may numerically simulate the disturbances without any knowledge of their physical nature and subtract them from the records the decontaminated records still may have a strange bow shaped form related to the near field ramp and the static displacement of the order of 1 10 5 m in this article the effects studied in this article seem to have a general character for apparently any feedback controlled broadband velocimeter

biennial quasi biennial and decadal oscillations of potential vorticity in the northern stratosphere seasonal and interannual variations of the northern hemisphere stratosphere on the 600 k isentropic surface 20 35 hpa are investigated by using observations for 1964 1996 an area diagnostic is defined in terms of ertel s potential vorticity pv which measures the area enclosed by pv contours as a function of equivalent latitude and is not tied to the spherical coordinate system data from all seasons are examined for oscillations with periods of 6 months to more than a decade spectral analysis of pv at equivalent latitudes from 20 n to the pole reveals several possible signals 1 in addition to the well known annual cycle of the polar vortex there is a striking semiannual oscillation of pv in middle equivalent latitudes at 34 53 n the semiannual oscillation is larger than the annual cycle this oscillation arises from the formation of a surf zone in winter due to planetary wave breaking superposed on the annual cycle 2 a signal associated with the quasi biennial oscillation qbo of the equatorial stratosphere with average period slightly less than 30 months is strongest at low equivalent latitudes and is apparent in middle equivalent latitudes up to 67 n through interaction with the annual cycle oscillations with periods of 20 2 and 8 5 months are generated these three spectral peaks at approximately 30 20 and 8 5 months have been observed in ozone and wind data and are seen here for the first time in pv 3 at middle to high equivalent latitudes on the other hand we observe biennial and associated 8 month oscillations related to the occurrence of stratospheric warmings and strong undisturbed vortices in midwinter to late winter the data record is remarkable in that at high equivalent latitudes strong and weak polar vortices alternated from year to year producing the biennial signal and a significant negative lag 1 year autocorrelation the addition of an 8 month harmonic generates a much better fit to the sharp late winter anomalies 4 south of 60 n a spectral peak at 10 6 years is observed with the clearest signal near 20 n this spectral peak may be caused by the solar cycle or it may arise through interaction of biennial and quasi biennial oscillations

the 2019 m w 5 7 changning earthquake sichuan basin china a shallow doublet with different faulting styles the increased seismic activity of the last 10 years in changning county of sichuan province comprised just small mostly ml 5 0 injection induced earthquakes the mw 5 7 earthquake of june 17 2019 is the largest event ever reported there moment tensor of the mainshock was remarkably dominated by a compensated linear vector dipole we resolve its fine structure showing it was a doublet allowing approximation by a thrust and strike slip subevent the mainshock nucleated as thrust faulting which together with the largest aftershocks can be linked with previously known reverse faults favorably oriented to regional stress field contrarily the strike slip segment of the mainshock less favorably oriented was probably facilitated by elevated pore pressure due to previous injections shallow active strike slip faulting not yet mapped in the region is a new feature important for future hazard assessment

comments on the paper reconnaissance of upper jurassic morrison formation ichnofossils rocky mountain region usa paleoenvironmental stratigraphic and paleoclimatic significance of terrestrial and freshwater ichnocoenoses by stephen t hasiotis

asperity break after 12 years the mw6 4 2015 lefkada greece earthquake the mw6 4 earthquake sequence of 2015 in western greece is analyzed using seismic data multiple point source modeling nonlinear slip patch and linear slip inversions reveal a coherent rupture image with directivity toward the southwest and several moment release episodes reflected in the complex aftershock distribution the key feature is that the 2015 earthquake ruptured a strong asperity which was left unbroken in between two large subevents of the mw6 2 lefkada doublet in 2003 this finding and the well analyzed cephalonia earthquake sequence of 2014 provide strong evidence of segmentation of the major dextral cephalonia lefkada transform fault ctf being related to extensional duplex transform zones we propose that the duplexes extend farther to the north and that the ctf runs parallel to the western coast of lefkada and cephalonia islands considerably closer to the inhabited islands than previously thought generally this study demonstrates faulting complexity across short time scales earthquake doublets and long time scales seismic gaps

source mechanism of mining induced seismic events resolution of double couple and non double couple models abstract traditional assumption about a seismic source as a double couple dc can represent a serious limitation for describing mechanisms of mining induced seismic events in mining conditions more general process than a shear slip can occur due to stress concentration on mined out areas we assume both non dc components within the dipole description of the source the moment tensor and a single force we processed five seismic events recorded at driefontein gold mine in south africa to demonstrate that waveform modeling is not successful enough due to poor information about the medium inversion of amplitudes of direct p and s waves is more prospective due to their smaller sensitivity to detail of the medium and possibility to correct them for ray bending and shear wave splitting prior to the inversion moreover we are able to estimate the error of the resulting mechanism due to neglect of ray bending all five events processed display non dc mechanisms which are significant at 95 considering the mismodelling of the rock mass by a homogeneous isotropic medium the source mechanisms are in agreement with the underground mining and geological structures one event has a sub vertical pressure single dipole complemented by an implosion which is the body force equivalent of a collapsing horizontal crack or a burst of a pillar supporting the hangingwall of a mined out area two events have mechanisms close to a pressure single couple all three events are located on pillars two out of these three events can be assigned with a downward single force as an alternative mechanism which matches the amplitude data successfully it is the force equivalent of a mined out area collapse when a rock mass falls from the hangingwall to the footwall the events are however rather strong which would require too large rock mass fallen one of the remaining events is a nearly horizontal tensile single couple corresponding to a vertical tensional fault it could be originated by a break of the hangingwall of a mined out area however the hypocenter of this event is deep into the footwall were there is no mining taking place the last event is mostly dc accompanied by a compensated compressive dipole which may be associated to nearly vertical dip slip along a fault in the hangingwall this event is located on the margin of a wide pillar which supports the interpretation

precursory signals of east asian winter cold anomalies in stratospheric planetary wave pattern the impacts of the stratospheric polar vortex changes on the tropospheric climate variability have been emphasized in previous studies the present study presents evidence for precursory signals of cold anomalies over east asia in the stratospheric wave pattern during november through march the leading two empirical orthogonal function eof modes of daily 50 hpa geopotential height anomalies along 65 n correspond to changes in the amplitude and phase of the stratospheric planetary wavenumber 1 respectively composite analysis is performed to unravel the temporal evolution of anomalies during 8 phases of 34 events identified based on the second eof mode with a complete life cycle for the period 1979 2016 the surface cold anomalies over eastern china emerge in phase 3 corresponding to negative and positive 50 hpa height anomalies on the north atlantic and russian far east sector respectively and peak in phase 5 corresponding to positive 50 hpa height anomalies over eurasia when the siberian high extends southeastward and the east asian trough deepens with anomalous surface northerly winds downward propagation of stratospheric signal is detected over western europe and western siberia the former is a source region of the tropospheric rossby wave trains propagating along the polar front jet and subtropical jet the downward propagation of stratospheric signal is related to the reflection of stratospheric planetary wavenumber 1 pattern and contributes to the development of the tropospheric rossby wave train that in turn leads to the strengthening of the siberian high and the deepening of the east asian trough

the rise collapse and compaction of mt mantap from the 3 september 2017 north korean nuclear test surveillance of clandestine nuclear tests relies on a global seismic network but the potential of spaceborne monitoring has been underexploited we used satellite radar imagery to determine the complete surface displacement field of up to 3 5 meters of divergent horizontal motion with 0 5 meters of subsidence associated with north korea s largest underground nuclear test combining insight from geodetic and seismological remote sensing we found that the aftermath of the initial explosive deformation involved subsidence associated with subsurface collapse and aseismic compaction of the damaged rocks of the test site the explosive yield from the nuclear detonation with best fitting source parameters for 450 meter depth was 191 kilotonnes of tnt equivalent our results demonstrate the capability of spaceborne remote sensing to help characterize large underground nuclear tests

dinosaur footprints from the lower cretaceous of northern spain their sedimentological and palaeoecological context abstract dinosaur footprints are described from two distinct horizons within the lower cretaceous sequence of the western cameros basin province of burgos northern spain footprints from a series of lacustrine carbonates in the berriasian rupelo formation show a rounded outline and are preserved as negative endichnia these footprints were probably formed by a bipedal ornithopod herbivore sauropod bones occur at a similar stratigraphic horizon at other localities in the basin the footprints support the sedimentological evidence that the lake was shallow with vegetated margins subject to frequent exposure tridactyl footprints unusually preserved as positive epichnia form a trackway on a sandstone bedding surface within the piedrahita de muno formation valanginian barremian this set of footprints was probably made by a bipedal theropod carnivore which inhabited an extensive floodplain environment the alternation of sandstones and overbank mudstones facilitated preservation of this set of footprints

relationship between stationary planetary wave activity and the east asian winter monsoon 1 the variability of both the stationary planetary wave activity and the east asian winter monsoon is strongly associated with the thermal contrast between oceans and landmasses in this study we explore the interannual relationship between the monsoon and the wave activity defined by an index of the difference in the divergence of eliassenpalm flux between 50 n at 500 hpa and 40 n at 300 hpa it is found that compared to the winters of low wave activity the equatorward propagation of planetary waves in the middle and upper troposphere is stronger in the high wave activity winters during these high activity winters the upward wave propagation from the troposphere into the stratosphere becomes weaker this is accompanied by a smaller perturbation in the polar vortex which tends to be colder and stronger in the meantime the east asian westerly jet stream the east asian trough the siberian high and the aleutian low all become weaker apparently in particular the weakening of the siberian high and the aleutian low decreases the northeasterly wind over east asia leading to a warming condition in the region especially in northeastern asia a further analysis reveals that the zonal wavenumber 2 pattern of planetary waves contributes dominantly to the variability of the east asian winter monsoon

processes for occurrence of strong cold events over eastern china abstracta strong cold event hit eastern china around 24 january 2016 with surface air temperature reaching more than 10 c below the climatological mean in most regions of eastern china south of 40 n a total of 37 strong cold events similar to the january 2016 event with temperature anomalies over eastern china exceeding 5 c have been identified during the winters from 1979 80 to 2015 16 a comparative analysis of events with surface temperature anomalies of the same intensity but limited to north of 40 n indicates that the southward invasion of cold air to eastern china south of 40 n is related to two factors one is the latitudinal location of the upper level wave train the surface siberian high and the midtropospheric east asian trough over the mid to high latitude eurasian continent the other is a subtropical upper level wave train emanating from the midlatitude north atlantic the emergence of the subtropical wave train is related to the positive phase of the north atlantic oscillation nao wh

the 9 september 2016 north korean underground nuclear test we characterize the seismic events that occurred in north korea on 9 september 2016 and south korea on 12 september 2016 the 9 september 2016 event was identified as an explosion and the two 12 september 2016 events were identified as natural earthquakes using the p s p and s wave spectral ratios pg lg pn lg and pn sn as discriminants the explosive event was relocated within the north korean nuclear test site using a relative location method and the 2006 north korea underground nuclear test as the master event and the epicenter was identified at 41 2976 degrees n latitude and 129 0804 degrees e longitude from the regional lg and rayleigh waves the body and surface wave magnitudes for the 9 september 2016 event were calculated as m b lg 4 8 0 2 and m s 4 2 0 1 by adopting an empirical magnitude yield relation for the body wave magnitude and assuming that the explosion was fully coupled and detonated at a normally scaled depth we estimated that the seismic yield was similar to 6 kt and the uncertainty range was between 3 and 11 kt if an overburied depth range between 780 and 1200 m was applied then the yield would be increased to 16 22 kt

a chronostratigraphic framework for the upper jurassic morrison formation western u s a the attached document is the authors final accepted submitted version of the journal article you are advised to consult the publisher s version if you wish to cite from it

reconnaissance of upper jurassic morrison formation ichnofossils rocky mountain region usa paleoenvironmental stratigraphic and paleoclimatic significance of terrestrial and freshwater ichnocoenoses seventy five types of ichnofossils documented during a four year reconnaissance study in the upper jurassic morrison formation demonstrate that highly diverse and abundant plants invertebrates and vertebrates occur throughout most of the morrison or equivalent strata invertebrate ichnofossils preserving the most environmentally and climatically sensitive in situ behavior of morrison organisms are in nearly all outcrops terrestrial ichnofossils record biotic processes in soil formation indicating soil moisture and water table levels freshwater ichnofossils preserve evidence of water depth salinity and seasonality of water bodies ichnofossils categorized as epiterraphilic terraphilic hygrophilic and hydrophilic new terms reflect the moisture regime where they were constructed the ichnofossils are vertically zoned with respect to physical chemical and biological factors in the environment that controlled their distribution and abundance and are expressed as surficial shallow intermediate and deep the sedimentologic stratigraphic and geographic distribution of morrison ichnofossils reflects the environmental and climatic variations across the basin through time marginal marine tidal to brackish water ichnofossils are mainly restricted to the windy hill member very large to small termite nests dominate the salt wash member similar size ranges of ant nests dominate the brushy basin member soil bee nests dominate in the salt wash decreasing in abundance through the brushy basin deeper and larger insect nests indicate more seasonal distribution of precipitation and rainfall shallower and smaller insect nests indicate either dry or wet substrate conditions depending on the nest architecture and paleopedogenic and sedimentologic character of the substrate trace fossil indicators of flowing or standing water conditions are dominant in the tidwell member and in fluvial sandstones of the salt wash and brushy basin members large communities of perennial freshwater bivalve traces are abundant in the tidwell and brushy basin members but to a lesser extent in the salt wash member shallow crayfish burrows indicating a water table level close to the surface 1 m are restricted to channel bank and proximal alluvial deposits in the salt wash recapture and brushy basin members sauropod theropod pterosaur and other vertebrate tracks occur throughout the morrison formation associated with alluvial lacustrine and transitional marine shoreline deposits ichnofossils and co occurring paleosols in the morrison reflect the local and regional paleohydrologic settings which record the annual soil moisture budget and were largely controlled by the climate in the basin contributions to near surface biologic systems by groundwater from distant sources were minor except where the water table perennially seasonally or ephemerally intersected the ground surface the jurassic morrison formation in the southern portion of the basin experienced a mosaic of seasonal climates that varied from a drier tidwell windy hill deposition to a wetter lower and middle salt wash deposition and slightly drier upper salt wash deposition tropical wet dry climate returning to a wetter tropical wet dry climate near the end of morrison deposition brushy basin deposition the northern part of the basin experienced similar trends across a mosaic of mediterranean climate types the range and mosaic pattern of wet dry morrison climates is analogous to the range of climates and their seasonal variability that dominates the african savanna today

palaeontological and sedimentological observations on nonmarine lameta formation upper cretaceous of maharashtra india their palaeoecological and palaeoenvironmental significance abstract the lameta formation upper cretaceous is exposed in parts of central and western india as detached outcrops and covers an area of nearly 5000 km 2 it generally rests on precambrian and gondwana rocks and is invariably capped by deccan trap volcanic flows in the nand and dongargaon areas of the chandrapur and nagpur districts of maharashtra the lameta formation covers more than 400 km 2 attains a thickness of 20 m and is richly fossiliferous the palaeontological and sedimentological observations strongly indicate alluvial limnic environment for the deposition of the lameta sediments under semi arid conditions different lithofacies representing channel overbank paludal and lacustrine subenvironments have been identified the biota represents terrestrial semiaquatic and aquatic communities and is represented by dinosaurs fishes crocodiles chelonia gastropods ostracodes charophytes coniferales and angiosperms the biota appears to be mainly controlled by the different lithofacies thereby suggesting strong palaeoecological and taphonomical control over their occurrence records of mass death of clupeids have been observed in many layers within the lacustrine clays a nesting site of sauropods has been found near pavna along with evidence of site fidelity a clutch with small oblong shaped eggs of avian like affinity has been also unearthed from this nesting site the lameta sediments were deposited in a freshwater environment that provided the preferred ecological niche for large scale breeding and nesting of sauropods

meridional and vertical out of phase relationships of temperature anomalies associated with the northern annular mode variability 1 using the ncar ncep reanalysis we here present evidence suggesting that the out of phase relationships of temperature anomalies both between the low and high latitudes and between the stratosphere and troposphere are intimately related to the meridional and downward propagation of anomalies of both signs the temperature anomalies propagate poleward and downward above the tropopause and propagate equatorward below the tropopause the characteristic time scale for anomalies of one polarity to propagate from the equator to the pole or the half period of the complete cycle is about 55 days the relatively slow meridional propagation helps to explain the well known seesaw oscillatory pattern between low and high latitudes found in monthly data the equatorward propagation in the troposphere is synchronized with the poleward propagation of the stratospheric temperature anomalies of the opposite sign in both low and high latitudes responsible for the out of phase relation between the stratospheric and tropospheric temperature anomalies in the polar region since it takes about 55 days for anomalies of one polarity to propagate from the tropics to the pole such an intimate linkage between the anomalies in the deep tropics and high latitudes would imply a longer lead time for intra seasonal climate prediction in the extratropics

asian jet waveguide and a downstream extension of the north atlantic oscillation abstract anomalous atmospheric fields associated with the north atlantic oscillation nao are analyzed on interannual and intraseasonal time scales in order to examine the extent to which the nao is a regional phenomenon analyses on the interannual time scale reveal that the nao signal is relatively confined to the euro atlantic sector in december while it extends toward east asia and the north pacific in february the difference is most clearly seen in the meridional wind anomaly which shows a wave train along the asian jet collocated with an anomalous vorticity source near the jet entrance diagnoses using a linear barotropic model indicate that this wave train is interpreted as quasi stationary rossby waves trapped on the asian jet waveguide and effectively excited by the anomalous upper level convergence over the mediterranean sea it is found that when the nao accompanies the mediterranean convergence mc anomaly most frequently seen in february the nao indeed has a much wider horizontal str

high precision location and yield of north korea s 2013 nuclear test 1 using north korea s 2009 nuclear test as reference and satellite imagery we show that the location and yield of north korea s 2013 nuclear test can be quickly and accurately determined based on seismic data north korea s 2013 nuclear test site is pinpointed by deriving relative location of north korea s 2009 and 2013 nuclear tests and using the previously determined location of the 2009 nuclear test while its yield is estimated based on the relative amplitude ratios of the lg waves recorded for both events the previously determined lg magnitude of 2009 nuclear test and burial depth inferred from satellite imagery north korea s 2013 test site is determined to be located at 41 17 26 88 n 129 4 34 68 e about 345 m south and 453 m west of its 2009 nuclear test site with a geographic precision of 94 m its yield is estimated to be 12 2 3 8 kt

integrated overview of the vertebrate fossil record of the ladrunan anticline spain evidence of a barremian alluvial lacustrine system in ne iberia frequented by dinosaurs abstract the barremian mirambel formation maestrazgo basin iberian chain ne spain preserves different types of dinosaur and other vertebrate fossils skeletal eggshell and ichnological remains a total of 31 vertebrate fossil sites and tracksites have been recognized within this unit in the ladrunan area teruel province detailed stratigraphic sedimentological and micropalaeontological analyses have also been performed in the unit a vertical sedimentary trend from alluvial dominated facies meandering river and related overbank areas to palustrine lacustrine facies and back has been defined for the mirambel formation in this area the depositional system was located close to the coastline as indicated by sporadic marine input in the lower part of the unit most fossil remains were recovered by surface collection as well as by the usual techniques used for macrovertebrate excavations the dinosaur record identified comprises ornithopods theropods and sauropods four distinct track bearing horizons have been identified the heterolithic nature and aggradation characteristic of the mirambel formation are favourable factors for track formation and preservation the dinosaur tracks consist of convex hyporeliefs or concave epireliefs that record the trackmakers as they frequented lakeshores alluvial floodplains and fluvial courses macrovertebrate bonebeds occur in alluvial settings poorly drained floodplains and ponds microvertebrate concentrations are located in shallow lacustrine deposits isolated skeletal elements can be found in a great variety of deposits attritional accumulation in a low energy depositional context is the general pattern of origin for the bone bearing fossil sites of the mirambel formation as regards the genetic framework the resulting skeletal assemblages are predominantly the result of physical factors with sedimentology as a key factor rather than biological phenomena eggshell fragments are frequent throughout the unit but are clearly more common in palustrine lacustrine deposits these can be taken to be parautochthonous bioclasts from nearby areas and might be indicative of the preferential affinity of the egg layers for wetlands and lakeshores

influence of the vertical and zonal propagation of stratospheric planetary waves on tropospheric blockings 1 case studies are used to elucidate the relationship between stratospheric planetary wave reflection and blocking formation in the troposphere the enhanced upward propagation of a planetary scale wave packet from the eurasian sector involving a euro atlantic blocking leads to a stratospheric sudden warming ssw following the weakening of the stratospheric westerly jet due to polar warming the stratospheric planetary wave packet then propagates downward over the american sector inducing a ridge over the north pacific as well as a trough over eastern canada in the upper troposphere the ridge promotes the formation of a pacific blocking this result explains why pacific blockings tend to form after ssw and why they are associated with suppressed upward propagation of planetary waves

nonisotropic radiation of the 2013 north korean nuclear explosion on 12 february 2013 north korea conducted an underground nuclear test in the northeastern mountainous part of the country the explosion reached magnitude mb 5 1 being recorded at most of seismic stations around the world and becoming one of the best ever recorded nuclear explosions in history similarly as other nuclear explosions buried in nevada kazakhstan or china the 2013 north korean explosion is characterized by a significant nonisotropic radiation this radiation is manifested by distinct sh and love waves in the wave field and is inconsistent with the model of a spherically symmetric source we show that the love waves are not generated by a tectonic earthquake triggered on a nearby fault structures but produced by asymmetry of the explosive source caused by presence of deviatoric stress in the surrounding rock the retrieved moment tensor of the 2013 explosion is characterized by the isotropic component of 57 5 the double couple component of 17 9 and the compensated linear vector dipole component of 24 7 the p t and n axes of the moment tensor are consistent with the principal axes of the regional tectonic stress in the korean peninsula a comparison of waveforms and particle motions of the 2013 explosion and the previous north korean nuclear explosion buried in 2009 indicates that the 2013 explosion was slightly more nonisotropic

moment tensor resolvability application to southwest iberia abstract we present a method to assess the uncertainty of earthquake focal mechanisms based on the standard theory of linear inverse problems we compute the uncertainty of the moment tensor m then map it into uncertainties of the strike dip and rake the inputs are source and station locations crustal model frequency band of interest and an estimate of data error the output is a six dimensional 6d error ellipsoid which shows the uncertainty of the individual parameters of m we focus on the double couple dc part of m the method is applicable both with and without waveforms the latter is particularly useful for network design as an example we present maps of dc resolvability for earthquakes in southwest europe computed without waveforms we find that the resolvability depends critically on frequency range and source depth shallow dc sources 10 km are theoretically better resolved than deeper sources 40 km and 60 km the dc resolvability of a 40 km deep event improves considerably when the portuguese network is supplemented by stations in spain and morocco the dc resolvability can be further improved by using a few ocean bottom seismometer obs stations or a dense land network a dense land network is able to resolve m well in spite of the large azimuthal gap which spans 200 the theoretical resolution analysis also explains the success of single station inversions when using a broad frequency range as exemplified by an application using waveforms of a m w 6 earthquake offshore iberia

intraseasonal variation of the strength of the east asian trough and its climatic impacts in boreal winter abstractthe east asian trough eat is a distinct component of the boreal winter circulation whose strength corresponds to the amplitude of the northern hemispheric stationary waves in this study the mechanism and climatic impacts of the intraseasonal variations of the eat s strength are investigated through composite analysis and dynamical diagnostics the significant roles played by the low frequency rossby wave rw and synoptic transient eddy te are revealed before the peaks of strong eat events an upper tropospheric rw train propagates across northern eurasia and interacts with preexisting surface cold anomalies over central siberia this pattern intensifies the siberian high and causes rw convergence toward the eat leading to 30 of the eat s amplification directly via the rw induced feedback forcing meanwhile rw weakens the background baroclinicity and reduces te activities near the entrance region of the north pacific storm track the te induced feedback forcing leads to another 30 of th

paleoenvironmental reconstruction of jurassic dinosaur habitats of the vega formation asturias spain jurassic aged strata of asturias spain contain trace fossils including sauropod theropod and ornithopod dinosaur footprints but their paleoenvironmental context has been relatively unstudied a coastally exposed continuous section at playa de vega shows a clear transition from the marine middle jurassic rodiles formation to the terrestrial upper jurassic vega formation within the 100 m of vega formation stratigraphy that was logged there four distinct types of paleosols were identified 1 entisols 2 inceptisols 3 vertisols and 4 composite or cumulative paleosols the paleosol types and their features indicate a floodplain depositional setting with short stature shrubby vegetation theropod and ornithopod tracks have been identified at the base of the section indicating that a dinosaurian fauna was present at playa de vega during the jurassic results from well characterized climofunctions based on modern soils and paleosol b horizon chemical composition of the inceptisols and vertisols yield mean annual precipitation estimates of 400 980 mm yr 1 and mean annual temperature estimates of 8 15 c the presence of vertisols with both evidence for shrink and swell behavior and dispersed pedogenic carbonate is consistent with a strongly seasonal precipitation regime the 13 c analyses of pedogenic carbonates yield values that range from 7 09 to 8 88 relative to vienna peedee belemnite vpdb and indicate carbon dioxide levels about six times pre industrial levels consistent with previous results the asturian vertebrate track assemblage is remarkably similar to that of the morrison formation western united states but it has greater overall richness the pattern is reversed for body fossils the reconstructed paleoenvironmental and paleoclimatic conditions indicate similar depositional settings in both places but with a cooler wetter more seasonal environment in asturias the greater seasonality indicated by the vega formation relative to the morrison formation may explain the observed differences in richness

stratospheric origin of cold surge occurrence in east asia 1 in the present study we have found a precursory signal in the stratospheric circulation prior to the cold surge occurrence in east asia over northern eurasia about one week before the cold surge occurrence strong stratospheric negative potential vorticity anomalies and rising of geopotential height are observed the dynamic linkage between the stratospheric perturbations and the tropospheric adjustment along with initial disturbances for a cold surge occurrence are discussed

tropospheric wave response to decelerated stratosphere seen as downward propagation in northern annular mode 1 baldwin and dunkerton 1999 found that negative northern annular mode nam anomalies sometimes descend all the way from the stratosphere into the lower troposphere however no viable mechanism has been proposed so far to account for the magnitude of the anomalies in the denser troposphere further analysis shows that the character of the anomaly changes across the tropopause above the tropopause the nam pattern is approximately zonal and its descent represents the descent of decelerated zonal mean winds this stratospheric change is explainable using theories similar to those for the descent of the zero wind line associated with a major stratospheric sudden warming however such a reversal in the zonal mean wind rarely reaches the denser troposphere the descent of the nam anomalies into the troposphere may be implying a different relationship between the stratosphere and the troposphere we note that in the troposphere the structure of the nam has a large wave component in some cases this wave component appears to react to the decelerated wind configuration aloft here we show observations of the wave component and the zonal mean component in comparison to corresponding nam events to show that the wave response is a sizable component of the nam anomaly in the troposphere we will also present a simple model calculation to show that tropospheric waves forced by topography can react to changing stratospheric winds these tropospheric waves can project directly onto the tropospheric nam patterns and produce anomalies in the index which appear to be connected to the negative nam anomalies in the stratosphere

propagation of the arctic oscillation from the stratosphere to the troposphere geopotential anomalies ranging from the earth s surface to the middle stratosphere in the northern hemisphere are dominated by a mode of variability known as the arctic oscillation ao the ao is represented herein by the leading mode the first empirical orthogonal function of low frequency variability of wintertime geopotential between 1000 and 10 hpa in the middle stratosphere the signature of the ao is a nearly zonally symmetric pattern representing a strong or weak polar vortex at 1000 hpa the ao is similar to the north atlantic oscillation but with more zonal symmetry especially at high latitudes in zonal mean zonal wind the ao is seen as a north south dipole centered on 40 45 n in zonal mean temperature it is seen as a deep warm or cold polar anomaly from the upper troposphere to 10 hpa the association of the ao pattern in the troposphere with modulation of the strength of the stratospheric polar vortex provides perhaps the best measure of coupling between the stratosphere and the troposphere by examining separately time series of ao signatures at tropospheric and stratospheric levels it is shown that ao anomalies typically appear first in the stratosphere and propagate downward the midwinter correlation between the 90 day low pass filtered 10 hpa anomaly and the 1000 hpa anomaly exceeds 0 65 when the surface anomaly time series is lagged by about three weeks the tropospheric signature of the ao anomaly is characterized by substantial changes to the storm tracks and strength of the midtropospheric flow especially over the north atlantic and europe the implications of large stratospheric anomalies as precursors to changes in tropospheric weather patterns are discussed

probable palaeogeographic influences of the lower cretaceous iberian rifting phase in the eastern cameros basin spain on dinosaur trackway orientations abstract the cameros basin sedimentary infill comprises a large essentially continental megasequence ranging from the tithonian upper jurassic to the albian lower cretaceous it occupies an area of some 5500 km2 and is home to around 300 dinosaur tracksites most of these tracksites are found in either the huerteles formation which is part of the oncala group berriasian or the enciso group lower aptian both of which represent early cretaceous lacustrine episodes dinosaur trackways n 1170 from both episodes were analysed in order to establish the preferred direction of dinosaur movement and to determine whether these movements were influenced by the palaeogeographic and palaeoenvironmental conditions of the area the huerteles formation is interpreted as a complex record of alluvial plain systems distally connected with a playa lake its dinosaur tracksites are distributed throughout its alluvial plain facies and trackways show two preferential unidirectional orientations 1 nw more or less parallel to the distribution of the facies belt and 2 nne the enciso group is represented by a wide and shallow lacustrine system connected with marine environments towards the se iberian basin realm and in close proximity to marine settings to the nw basque cantabrian basin realm rendering the cameros basin as the only continental connection between the ebro and iberian massifs the fluctuating but always shallow water level of the system with frequent desiccations probably allowed dinosaurs to pass through the lake basin as a consequence of these paleogeographic restrictions the dinosaur trackways generally show a bidirectional ne sw orientation despite the temporal and geographical differences between the huerteles formation and enciso group the ichnocenoses of both are dominated by theropod dinosaur trackways 85 as a mean value this is probably explained by these dinosaurs being more active than others a consequence of their searching hunting behaviour

north korea s 2017 test and its nontectonic aftershock seismology illuminates physical processes occurring during underground explosions not all yet fully understood the thus far strongest north korean test of 3rd september 2017 was followed by a moderate seismic event ml 4 1 after 8 5 minutes here we provide evidence that this aftershock was a non tectonic event which radiated seismic waves as a buried horizontal closing crack this vigorous crack closure occurring shortly after the blast is studied in the north korea test site for the first time the event can be qualitatively explained as rapid destruction of an explosion generated cracked rock chimney due to cavity collapse although other compaction processes cannot be ruled out

the association between stratospheric weak polar vortex events and cold air outbreaks in the northern hemisphere previous studies have identified an association between temperature anomalies in the northern hemisphere and the strength of stratospheric polar westerlies large regions in northern asia europe and north america have been found to cool during the mature and late stages of weak vortex events in the stratosphere a substantial part of the temperature changes are associated with changes in the northern annular mode nam and north atlantic oscillation nao pressure patterns in the troposphere the apparent coupling between the stratosphere and the troposphere may be of relevance for weather forecasting but only if the temporal and spatial nature of the coupling is known using 51 winters of re analysis data we show that the development of the lower tropospheric temperature relative to stratospheric weak polar vortex events goes through a series of well defined stages including the formation of geographically distinct cold air outbreaks at the inception of weak vortex events a precursor signal in the form of a strong high pressure anomaly over northwest eurasia is associated with long lived and robust cold anomalies over asia and europe a few weeks later near the mature stage of the weak vortex events a shorter lived cold anomaly emerges off the east coast of north america the probability of cold air outbreaks increases by more than 50 in one or more of these regions during all phases of the weak vortex events this shows that the stratospheric polar vortex contains information that can be used to enhance forecasts of cold air outbreaks as large changes in the frequency of extremes are involved this process is important for the medium range and seasonal prediction of extreme cold winter days three hundred year pre industrial control simulations by 13 coupled climate models corroborate our results copyright 2010 royal meteorological society and crown copyright

taphonomy of jack s birthday site a diverse dinosaur bonebed from the upper cretaceous two medicine formation of montana jack s birthday site is a diverse vertebrate assemblage from the upper two medicine formation of western montana age is roughly 74 ma the site covers roughly 3000 m2 and excavations over 140 m2 a large bone sample 1600 skeletal elements allowed statistical evaluation of the preservational and compositional variation within the site evidence including sedimentary facies plant and invertebrate fossils and bone orientation and condition indicates jack s birthday site represents part of a small shallow floodplain lake lithologies and fossil preservation vary from northwest to southeast over a distance of 50 m this variation represents a transition from lake through shoreline to marginal shoreline floodplain environments containing ten dinosaur taxa and a variety of non dinosaurs jack s birthday site provides one of the best single faunal samples of the region the vertebrate assemblage includes two taphonomic fractions the first consisting of attritional predominantly isolated and allochthonous elements represents a time averaged assemblage the other consists of associated parautochthonous remains restricted to a single horizon taxa represented by associated remains include three iguanodontoids hypacrosaurus prosaurolophus and gryposaurus and the theropod troodon associated individuals of these taxa have non random distributions within the site fisher s exact test p 0 01 and observed taxonomic clustering may reflect group behavior and or event mortality the four or more troodon represent the first described multi individual troodontid occurrence the diversity and spatial complexity of the parautochthonous fraction of the birthday site assemblage is difficult to explain discussion of possible event mortality mechanisms focuses on three drought botulism and cyanobacterial toxicosis these share an ability to act over an ecologically significant period of time affect a variety of species and concentrate mortality along water sources aspects that may have been important in generating the birthday site assemblage evidence at the site favors drought or perhaps a drought botulism hypothesis however taxonomic clusters could represent completely separate events with a variety of causes

paleobiogeographic distribution of testudinata and neosuchian crocodyliformes in the morrison formation upper jurassic of north america evidence of habitat zonation abstract nearly 150 occurrences of turtles and neosuchian crocodyliforms in the upper jurassic morrison formation indicate that by number of localities and number of specimens both are preferentially preserved off the colorado plateau in deposits in the eastern and northern parts of the morrison basin suggesting that these latter areas contained wetter paleoenvironments and either were more populated with these semi aquatic taxa or more frequently preserved their remains compared with areas to the south and west cursorial crocodylomorphs occur at more sites and in greater numbers on the colorado plateau than to the east and north but this pattern is only significant by number of specimens previous suggestions of wetter paleoenvironmental conditions on floodplains distal to the southwestern source areas on the colorado plateau or western source areas for northern outcrops based on geological and microvertebrate data seem to be borne out by these data from semi aquatic mesovertebrates

advanced seismic analyses of the source characteristics of the 2006 and 2009 north korean nuclear tests in 2006 and 2009 north korea conducted underground nuclear tests at a remote mountainous site in the northeastern part of the country both events were small leading to uncertainties for location yield estimation and discrimination based on seismic observations the objectives of the studies described in this paper have been to more fully exploit data from the international monitoring system ims network and other unclassified sources e g incorporated research institutions for seismology iris japanese national research institute for earth science and disaster prevention nied to analyze these nuclear tests we have used differential waveform interferometry dwif to refine relative locations for the tests and extended the methodology using observations from regional stations to estimate relative emplacement depths which are consistent with explosion source model predictions for broadband regional p wave spectral ratios topographic data from the test site were analyzed to constrain relative locations and depths needed for containment of the two tests based on normal testing practice network averaged teleseismic p wave spectra were inverted using a model based approach and provide explosion yield estimates in the range 0 6 1 0 kt for the 2006 test and 2 0 4 8 kt for the 2009 test depending on assumed emplacement depth detailed spectral analysis of broadband regional p observations are most consistent with theoretical explosion models with yields of 0 9 and 4 6 kt for the 2006 and 2009 tests respectively with associated source depths of 200 and 550 m consistent with previous studies the surface wave m s magnitudes for the 2006 and 2009 tests provide anomalously large m s yield estimates and problematic m s m b identification characteristics finite difference simulations of long period surface wave signals incorporating tensile prestress consistent with the regional tectonics lead to predicted m s values that agree much better with the observed values

observational evidence of a stratospheric influence on the troposphere by planetary wave reflection abstract recent studies have pointed out the impact of the stratosphere on the troposphere by dynamic coupling in the present paper observational evidence for an effect of downward planetary wave reflection in the stratosphere on northern hemisphere tropospheric waves is given by combining statistical and dynamical diagnostics a time lagged singular value decomposition analysis is applied to daily tropospheric and stratospheric height fields recomposed for a single zonal wavenumber a wave geometry diagnostic for wave propagation characteristics that separates the index of refraction into vertical and meridional components is used to diagnose the occurrence of reflecting surfaces for zonal wavenumber 1 this study suggests that there is one characteristic configuration of the stratospheric jet that reflects waves back into the troposphere when the polar night jet peaks in the high latitude midstratosphere this configuration is related to the formation of a reflecting surface for vertical propagation

application of vertebrate trace fossils to palaeoenvironmental analysis abstract this is a review of the main uses of vertebrate trace fossils ichnofabrics and ichnofacies in the palaeoenvironmental analysis of sedimentary sequences the article accounts for the significant developments produced in the last three decades including the application of the ichnofacies concept to vertebrate trace fossils recognition of footprints in cross sectional view and their distinction from inorganic structures and burrow fills is first discussed the response of different substrates showing contrasting water content and imprinted by different animals or devices is compared in terms of the morphology of the resultant footprint trackways with sand crescents are typical of aeolian cross strata and are absent in associated flat lying to low angle deposits thick packages of highly bioturbated sandy dune and interdune sediments have been interpreted as reflecting periods of increased rainfall neoichnological observations in modern lake basins suggest that distinct zones can be recognized in the margins of fossil ponds and lakes including onshore shoreline and shallow subaqueous zones abundant flamingo like footprints and flamingo nest mounds are good indicators of alkaline and or saline lake waters hippopotamus trails are found closely associated with modern and fossil freshwater wetlands dinosaur and pterosaur swim traces from lacustrine and fluvial deposits can be used to estimate water depth turtle crocodile amphibian hippopotamus and fish swim traces allow one to infer a subaqueous substrate certain modern intertidal fish feeding traces are oriented with the predominant tidal current and can be used as palaeocurrent indicators the preferential orientation of tetrapod trackways in lacustrine and fluvial deposits is analyzed vertebrate trace fossils can help to infer discharge variability in fluvial channels the descriptions of vertebrate ichnofabrics are commonly limited to heavily bioturbated beds due to trampling by vertebrates and to a few examples of ichnofabrics with discrete trace fossils the nature and implications of the recognized vertebrate ichnofacies are still being debated and have a limited utility in palaeoenvironmental analysis the distinction of a potential vertebrate burrow ichnofacies in carbonate bearing palaeosols is proposed to represent well drained soils developed under arid or semiarid climate

on the three dimensional propagation of stationary waves abstract a locally applicable nonzonally averaged conservation relation is derived for quasi geostrophic stationary waves on a zonal flow a generalization of the eliassen palm relation the flux which appears in this relation constitutes it is argued a useful diagnostic of the three dimensional propagation of stationary wave activity this is illustrated by application to a simple theoretical model of a forced rossby wave train and to a northern hemisphere winter climatology results of the latter procedure suggest that the major forcing of the stationary wave field derives from the orographic effects of the tibetan plateau and from nonorographic effects diabatic heating and or interaction with transient eddies in the western north atlantic and north pacific oceans and siberia no evidence is found in the data for wave trains of tropical origin forcing by the orographic effects of the rocky mountains seems to be of secondary importance

interannual variations of stationary planetary wave activity in the northern winter troposphere and stratosphere and their relations to nam and sst 1 with the national centers for environmental prediction national center for atmospheric research ncep ncar reanalysis data from 1958 to 1998 two teleconnection patterns in the eliassen palm ep flux divergence field due to stationary planetary waves with wavenumbers wns 1 to 3 are studied in the northern hemisphere winter both patterns appear as dipole structures with divergence of ep flux in the north and convergence in the south or vice versa one dipole evolves mainly in the stratosphere and is referred to as the stratospheric interannual oscillation sio the other evolves mostly in the troposphere and is referred to as the tropospheric interannual oscillation tio the tio and the sio are shown to be associated with anomalous meridional planetary wave propagation in the troposphere and stratosphere respectively the upward and poleward refraction of planetary waves into the polar waveguide across the tropopause is closely linked to the tio examination of individual waves indicates that the tropospheric dipole ofep flux divergence comes basically from wn 3 whereas the stratospheric one comes totally from wns 1 and 2 the reduced refraction of planetary waves into the polar waveguide across the tropopause associated with positive tio index is dominantly contributed from both wns 1 and 2 regression and correlation analyses suggest that the tio is closely related to the northern annular mode nam its relation to the sea surface temperature sst is consistent with previous studies on the relation of nam to sst on the other hand the sio is shown to be closely associated with anomalous zonal mean winds in the subtropics of the midstratosphere and has a moderate correlation with an augmented pacific north american pna pattern in 500 hpa geopotential height for the leading eof of stratospheric u variability the sio accounts for a smaller fraction than the tio however with the teleconnectivity in stratospheric ep flux divergence one can distinguish a stratospheric variation of anomalous north south planetary wave propagation from the total amount of wave activity entering the stratosphere which may help us to understand the variability of transport circulation in the stratosphere significant correlation of sio with tropical sst reveals that tropical sst is leading the sio by up to around 9 months which suggests a strong impact of el nino southern oscillation enso on the sio planetary waves tend to be bent poleward in the midstratosphere when there is a warm event the situation tends to be reverse during a cold event

response of the stratosphere to interannual variability of tropospheric planetary waves a primitive equation global model of the middle atmosphere is used to investigate the response of the extratropical stratosphere to different levels of wave forcing from steady perturbations of the geopotential height near the tropopause the response of the stratosphere is compared to that in quasi geostrophic beta plane models used in previous studies the primitive equation model exhibits three flow regimes under perpetual january conditions strong westerly steady flow for small wave amplitude forcing strong westerly but unsteady flow for moderate wave amplitude forcing and oscillations between easterly and westerly flow for large wave amplitude forcing the regimes for low and high forcing are analogous to solutions of the simpler holton mass hm quasi geostrophic model the moderate forcing regime does not occur in the hm model and it is attributed to instability of the strongly sheared flow generated by planetary waves in the upper stratosphere we also show how the observed patterns of interannual variability in the winter stratosphere can be explained in terms of these three flow regimes in the northern hemisphere the flow often enters the high forcing regime where variations in conditions in the early winter flow or quasi steady upper tropospheric planetary wave amplitudes make similar contributions to the interannual variability in the stratospheric circulation for the southern hemisphere we suggest that the flow alternates between the low and moderate forcing regimes through year to year changes in the amplitude of quasi steady waves near the tropopause this mechanism produces large enough changes to explain the interannual variability in the southern stratosphere

north america s largest dinosaur trackway site implications for morrison formation paleoecology little known exposures of the upper jurassic morrison formation from the purgatoire valley of southeastern colorado have yielded the world s largest continuously mapped assemblage of dinosaur trackways body fossils include plant invertebrate and vertebrate remains indicative of predominantly fresh water conditions the tracks occur in a lacustrine sequence characterized by 1 shallow water shales 2 micritic shoreface limestones with ooids intraclasts ripple marks mud cracks and 3 minor quartzose sandstone with salt crystal casts analysis of these sedimentary facies suggests that in southeastern colorado lakes were larger and longer lived than in other morrison paleoenvironments trackway orientations and footprint depth contours pinpoint the location of the paleoshoreline at successive levels in the section detailed mapping of 1 300 footprints in bed 2 has revealed more than 100 trackways which testify to the activity of both quadrupedal and bipedal dinosaurs the respective ratio based on trackway counts is 40 60 the quadrupedal tracks are attributed to sauropods and represent the first ever discovered in north america they also exhibit the first known manus claw impressions and are in need of formal description more than 90 of the bipedal tridactyl prints lack claw impressions and are tentatively therefore referred to the ornithopoda cf gypsichnites possibly a camptosaurus the small proportion with distinct claw impressions may represent allosaurus resulting estimates of species diversity 5 and predator prey ratio 1 30 are in general agreement with the estimates of other authors based on skeletal remains and they suggest that the purgatoire river tracks may accurately reflect the composition of the dinosaur fauna distinctive groupings of parallel non overlapping trackways suggest gregarious behavior among sauropods and tridactylous forms

source analysis of the memorial day explosion kimchaek north korea 1 a series of source inversions are performed for the 25 may 2009 memorial day north korean seismic event using intermediate period 10 50 s complete waveform modeling an earthquake source is inconsistent with the data and the best fit full seismic moment tensor is dominantly explosive 60 with a moment magnitude mw of 4 5 a pure explosion solution yields a scalar seismic moment of 1 8 1022 dyne cm mw4 1 and fits the data almost as well as the full solution the difference between the full and explosion solutions is the predicted fit to observed tangential displacement which requires some type of non isotropic non explosive radiation possible causes of the tangential displacement are additional tectonic sources tensile failure at depth and anisotropic wave propagation similar displacements may be hidden in the noise of the 2006 event future analyses of this type could be used to identify and characterize non earthquake events such as explosions and mine collapses

short paper fossil vertebrate tracks and indenter mechanics a reconnaissance study is outlined showing how an improved understanding of the formation and character of fossil vertebrate tracks in soft sediments is provided by the application of the mechanical engineer s indenter theory supported by complementary scaled laboratory experiments only the footprint at the bottom of the shaft cut by the animal9s limbs in general offers the best preservation of the shape of the underside of the foot the character of the foot is less well preserved in the deformed bedding beneath the footprint and among laminae deposited in the shaft after the passage of the animal this understanding will help to reduce errors in the use of tracks in taxonomic biostratigraphic palaeoecological behavioural and environmental studies when a limbed vertebrate traverses yielding sediment the limbs deform the substrate into tracks which vary with the nature size and gait of the animal the forcefulness of its limb movements and the sediment properties most previous geological work on tracks and trackways has emphasized their taxonomic biostratigraphical palaeocological and behavioural significance lockley 1986 leonardi 1987 but without an adequate understanding of their environmental implications lockley 1986 and in particular their genesis and preservation as trace fossils the response of an elastic plastic material to an indenter or punch both in terms of theory calladine 1969 hill 1971 johnson et al 1982 and in the light of qualitative laboratory experiments provides a general mechanical model for track formation and a basis for the assessment of track preservation in sediments the indenter represents the animal9s

radar reveals north korea s nuclear test moved a mountain mount mantap shifted by more than 3 metres but no indication of widespread collapse mount mantap shifted by more than 3 metres but no indication of widespread collapse

the influence of stratospheric vortex displacements and splits on surface climate abstracta strong link exists between stratospheric variability and anomalous weather patterns at the earth s surface specifically during extreme variability of the arctic polar vortex termed a weak vortex event anomalies can descend from the upper stratosphere to the surface on time scales of weeks subsequently the outbreak of cold air events have been noted in high northern latitudes as well as a quadrupole pattern in surface temperature over the atlantic and western european sectors but it is currently not understood why certain events descend to the surface while others do not this study compares a new classification technique of weak vortex events based on the distribution of potential vorticity with that of an existing technique and demonstrates that the subdivision of such events into vortex displacements and vortex splits has important implications for tropospheric weather patterns on weekly to monthly time scales using reanalysis data it is found that vortex splitting events are correl

moment tensor analysis of very shallow sources an issue for moment tensor mt inversion of shallow seismic sources is that some components of the green s functions have vanishing amplitudes at the free surface which can result in bias in the mt solution the effects of the free surface on the stability of the mt method become important as we continue to investigate and improve the capabilities of regional full mt inversion for source type identification and discrimination it is important to understand free surface effects on discriminating shallow explosive sources for nuclear monitoring purposes it may also be important in natural systems that have very shallow seismicity such as volcanic and geothermal systems we examine the effects of the free surface on the mt via synthetic testing and apply the mt based discrimination method to three quarry blasts from the humming albatross experiment these shallow chemical explosions at 10 m depth and recorded up to several kilometers distance represent rather severe source station geometry in terms of free surface effects we show that the method is capable of recovering a predominantly explosive source mechanism and the combined waveform and first motion method enables the unique discrimination of these events recovering the design yield using seismic moment estimates from mt inversion remains challenging but we can begin to put error bounds on our moment estimates using the network sensitivity solution technique ford et al 2010 online material figures showing synthetic tests for a pure explosion and a composite source at local distances and table of moment tensor components

regional paleohydrologic and paleoclimatic settings of wetland lacustrine depositional systems in the morrison formation upper jurassic western interior usa abstract during deposition of the upper jurassic morrison formation water that originated as precipitation in uplands to the west of the western interior depositional basin infiltrated regional aquifers that underlay the basin this regional groundwater system delivered water into the otherwise dry continental interior basin where it discharged to form two major wetland lacustrine successions a freshwater carbonate wetland lacustrine succession formed in the distal reaches of the basin where regional groundwater discharged into the denver julesburg basin which was a smaller structural basin within the more extensive western interior depositional basin an alkaline saline wetland lacustrine complex lake t oo dichi formed farther upstream where shallower aquifers discharged into the san juan paradox basin which was another small structural basin in the western interior depositional basin these were both wetlands in the sense that groundwater was the major source of water input from surface and meteoric water was limited in both basins lacustrine conditions developed during episodes of increased input of surface water inclusion of wetlands in our interpretation of what had previously been considered largely lacustrine systems has important implications for paleohydrology and paleoclimatology the distal carbonate wetland lacustrine deposits are well developed in the morrison formation of east central colorado occupying a stratigraphic interval that is equivalent to the lower morrison but extends into the upper morrison formation sedimentologic paleontologic and isotopic evidence indicate that regional groundwater discharge maintained shallow hydrologically open well oxygenated perennial carbonate wetlands and lakes despite the semi arid climate wetland deposits include charophyte rich wackestone and green mudstone lacustrine episodes in which surface water input was significant were times of carbonate and siliciclastic deposition in scarce deltaic and shoreline deposits marginal lacustrine deposits include ooid and skeletal packstone grainstone siltstone and sandstone distal lacustrine units are skeletal mudstone wackestone microbialites and laminated siliciclastic mudstone differentiation between wetlands and distal lacustrine units is not always possible palustrine features magadi type chert mtc and evaporites record episodes of increased aridity and exposure farther upstream during deposition of the upper part of the brushy basin member the ancestral uncompahgre uplift imposed a barrier to shallow eastward flowing groundwater that discharged into the san juan paradox basin on the upstream side of the uplift this created the closed hydrologic setting necessary for development of an alkaline saline wetland lacustrine complex lake t oo dichi silicic volcanic ash delivered by prevailing winds from calderas west and southwest of the basin contributed to the pore water evolution in the sediments a distinctive lateral hydrogeochemical gradient reflecting increasing salinity and alkalinity in the pore waters altered the ash to a variety of authigenic minerals that define concentric zones within the basin the basinward progression of diagenetic mineral zones is smectite clinoptilolite analcime potassium feldspar albite the groundwater fed wetlands were shallow and frequently evaporated to dryness scarce laminated gray mudstone beds record distinct episodes of freshwater lacustrine deposition that resulted from intermittent streams that carried detritus well out into the basin

interdecadal variations of the east asian winter monsoon and their association with quasi stationary planetary wave activity abstract interdecadal variations of the east asian winter monsoon eawm and their association with the quasi stationary planetary wave activity are analyzed by using the 40 yr european centre for medium range weather forecasts re analysis dataset and the national centers for environmental prediction national center for atmospheric research reanalysis dataset it is found that the eawm experienced a significant weakening around the late 1980s that is the eawm was strong during 1976 87 and became weak after 1988 this leads to an obvious increase in the wintertime surface air temperature as well as a decrease in the frequency of occurrence of cold waves over east asia the dynamical process through which the eawm is weakened is investigated from the perspective of quasi stationary planetary waves it is found that both the propagation and amplitude of quasi stationary planetary waves have experienced obvious interdecadal variations which are well related to those of the eawm compared to the period 1976

a review of dinosaur track occurrences from the morrison formation in the type area around dinosaur ridge abstract although the type section of the morrison formation near denver colorado now also well known as dinosaur ridge has since 1877 been world famous as the source of iconic late jurassic dinosaurs like stegosaurus apatosaurus and diplodocus little detailed information has been published on fossil footprints from the formation in this area late jurassic morrison footprints were not reported from the type section at dinosaur ridge until the early 1990s since then other footprints have been reported and their precise stratigraphic occurrences documented to date diagnostic examples of theropod sauropod and thyreophoran stegosaur tracks have been documented from at least three different locations the quality of preservation of these tracks ranges from moderately good to quite poor nevertheless more than 25 individual footprints including some undertracks have been identified unequivocally including several manus pes sets of quadrupedal trackmakers the track assemblages are typical of many small morrison formation ichnofaunas and are consistent with what is known of the body fossil assemblages the track assemblage is reviewed and compared with summary data from the 64 morrison formation tracksites currently known

tracking the yellow dragons implications of china s largest dinosaur tracksite cretaceous of the zhucheng area shandong province china abstract surfaces with more than 2200 dinosaur footprints from the huanglonggou yellow dragon valley site near zhucheng in shandong province were excavated for scientific study and with a view to future development as an educational site suitable for further research and tourism although geographically close to spectacular and historically famous upper cretaceous sites yielding vast bone assemblages representing giant hadrosaurs and other dinosaurs from the wangshi group the tracksite is in the lower cretaceous yangjiazhuang formation equivalent in part to the longwangzhuang formation represents an entirely different dinosaurian fauna dominated by small theropods in contrast to a recent pre excavation study of a localized outcrop which identified only three theropod track morphotypes in a sample of 135 tracks the present study has identified at least 2000 additional tracks including those of sauropods and turtles it is therefore possible to present a more complete interpretation of the site based on the larger and more diverse track assemblage presently exposed three theropod track morphotypes are identified as grallatorid morphotypes a and b with the latter assigned to grallator yangi comb nov and corpulentapus lilasia tracks have been identified from at least 5 levels of which level 4 exhibits the vast majority in an excellent state of preservation other recent studies which we re evaluate suggest the tracks help define an ene wsw shoreline with the lake center to the sse in terms of number of tracks documented the huanglonggou site is one of the largest dinosaur tracksites in china or indeed in the world

non double couple earthquakes 1 theory historically most quantitative seismological analyses have been based on the assumption that earth quakes are caused by shear faulting for which the equiv alent force system in an isotropic medium is a pair of force couples with no net torque a double couple or dc observations of increasing quality and coverage however now resolve departures from the dc model for many earthquakes and find some earthquakes especially in volcanic and geothermal areas that have strongly non dc mechanisms understanding non dc earth quakes is important both for studying the process of faulting in detail and for identifying nonshear faulting processes that apparently occur in some earthquakes this paper summarizes the theory of moment tensor expansions of equivalent force systems and analyzes many possible physical non dc earthquake processes contrary to long standing assumption sources within the earth can sometimes have net force and torque components described by first rank and asymmetric sec ond rank moment tensors which must be included in analyses of landslides and some volcanic phenomena non dc processes that lead to conventional symmetric second rank moment tensors include geometrically complex shear faulting tensile faulting shear faulting in an anisotropic medium shear faulting in a heteroge neous region e g near an interface and polymorphic phase transformations undoubtedly many non dc earthquake processes remain to be discovered progress will be facilitated by experimental studies that use wave amplitudes amplitude ratios and complete waveforms in addition to wave polarities and thus avoid arbitrary assumptions such as the absence of volume changes or the temporal similarity of different moment tensor com ponents

interannual variability of the east asian winter monsoon and related modulations of the planetary waves abstractinterannual variability of the east asian winter monsoon is investigated through composite analysis applied to observational data for 50 recent years although the monsoon activity itself is confined into the lower troposphere its midwinter variability tends to accompany upper tropospheric geopotential height anomalies similar to the eurasian eu and western pacific wp teleconnection patterns the eu like pattern is characterized by a wavy signature over the eurasian continent and the north atlantic with surface temperature anomalies over the far east and north america in the wp like pattern a meridional dipole of upper level height anomalies is evident over the far east these anomaly patterns related to the anomalous winter monsoon activity are found to accompany marked modulations of the climatological development of the upper tropospheric planetary waves from late autumn to midwinter enhanced monsoon activity in january associated with the wp like pattern involves anomalous seasonal

simulated weathering of dinosaur tracks and the implications for their characterization digital models of the tracks of bipedal theropod and ornithopod dinosaurs and the quadrupedal tracks of a sauropod were computationally eroded to investigate the effects of erosion on the shapes sizes and diagnostic details of fossil tracks narrow and or angular details such as claw marks interdigital ridges and internal ridges are removed early in erosion creating the potential for misidentification of eroded theropod tracks as those of ornithopods however with the erosion models presented here all tracks retain their basic shapes as indicated by the relative constancy of their interdigital angles and by the relative constancy of their footlength footwidth ratios surface lengths of tracks did not increase significantly with erosion so that dinosaurian hip height and speed estimates derived from trackways would not be greatly in error if based on eroded surface tracks synthetic undertracks from the surface tracks were also produced using information from published physical models of trac

first report of sauropod tracks from the upper jurassic tianchihe formation of guxian county shanxi province china abstract this paper presents the first report of sauropod tracks from the upper jurassic of shanxi province china dinosaur tracks appear concentrated in five trackways in different stratigraphic levels of the late jurassic tianchihe formation tracks are dominantly small and medium size sauropod tracks and are tentatively assigned to brontopodus based on preserved track morphology trackway pattern and statistical analysis the tianchihe formation in which the tracks appear shows a gradual change from meandering fluvial to sandy braided fluvial depositional systems developed in a seasonally arid environment comparisons of the evaluated speed of bipedal to quadruped trackways indicate that the slower walk more easily produces pes dominated overprints trackways in the guxian tracksite appear following different orientations suggesting that these trackways were produced by different sauropods at different times an unusual trackway following a curved pattern has been identified in the site and could represent a special locomotion character or a social behavior the presence of eolian deposits in central shanxi province could have acted as a paleogeographic and paleoenvironmental barrier for the dispersion of the yanliao biota that survived in northern hebei western liaoning and northestern shanxi province to the ordos basin during the late jurassic

the arctic oscillation signature in the wintertime geopotential height and temperature fields the leading empirical orthogonal function of the wintertime sea level pressure field is more strongly coupled to surface air temperature fluctuations over the eurasian continent than the north atlantic oscillation nao it resembles the nao in many respects but its primary center of action covers more of the arctic giving it a more zonally symmetric appearance coupled to strong fluctuations at the 50 hpa level on the intraseasonal interannual and interdecadal time scales this arctic oscillation ao can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft it is proposed that the zonally asymmetric surface air temperature and mid tropospheric circulation anomalies observed in association with the ao may be secondary baroclinic features induced by the land sea contrasts the same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature sea level pressure and 50 hpa height over the past 30 years parts of eurasia have warmed by as much as several k sea level pressure over parts of the arctic has fallen by 4 hpa and the core of the lower stratospheric polar vortex has cooled by several k these trends can be interpreted as the development of a systematic bias in one of the atmosphere s dominant naturally occurring modes of variability

seismic source summary for all u s below surface nuclear explosions a summary of information is presented for all u s nuclear tests detonated below the earth s surface the data include explosion times locations yields and depths of burial as well as geophysical information about working point media and for the underground explosions data about surface collapse subsidence phenomena this summary is intended to furnish available and up to date data useful for studies of seismic and hydroacoustic sources as well as for studies of the seismic and hydroacoustic transmission characteristics of the earth manuscript received 2 july 2001

tropospheric impact of reflected planetary waves from the stratosphere 1 a reflection of stratospheric planetary waves and its impact on the troposphere during a stratospheric sudden warming of march 2007 are investigated zonal propagation and reflection of the planetary waves is clearly seen in the longitude height sections of the eddy geopotential height and the vertical and zonal component of the three dimensional wave activity flux a wave packet propagating upward and eastward from eurasian continent was reflected by a negative wind shear in the upper stratospheric westerly jet caused by stratospheric warming waves then propagated downward to the american atlantic sector of the troposphere which led to the formation of a deep trough over the atlantic and brought cold weather to the northeastern part of the american continent

the effect of reflecting surfaces on the vertical structure and variability of stratospheric planetary waves the effects of an upper stratospheric reflecting surface on the vertical structure of stratospheric planetary waves are considered a diagnostic of the basic state wave propagation characteristics which is particularly useful for determining the existence and location of turning surfaces for meridional and vertical propagation is developed the diagnostic used is a more accurate indicator of wave propagation regions than the index of refraction because it diagnoses meridional and vertical propagation separately the diagnostic is tested on a series of simple models both steady state and time dependent it is found that the stratospheric waveguide sets the meridional wavenumber of the waves regardless of the characteristics of their tropospheric forcing making it easier to understand the effects of damping and turning surfaces on the vertical structure of the waves the diagnostic is then applied to observations of the southern hemisphere winter of 1996 it is shown that the differences in vertical wave structure between middle and late winter can be explained as a linear response to the seasonal evolution of the basic state which involves a formation of a reflecting surface in late winter it is also shown that on daily timescales wave mean flow interactions cause significant changes in the basic state propagation characteristics for periods of a few days these changes along with the time variations in the forcing of the waves are responsible for the observed daily timescale variations in wave structure the fact that the observed evolution of the waves and the basic state are consistent with linear or quasi linear wave theory depending on the timescale looked at supports the applicability of the theory as well as the validity of the observations

some observations on trackway evidence for gregarious behavior among small bipedal dinosaurs abstract although trackway evidence for social behavior herding or gregariousness has been demonstrated for large mainly quadrupedal dinosaurs until recently footprint evidence for herding among small bipedal dinosaurs has been sparse recent reports now increase the number of sites suggestive of social behavior to nine found in strata of early jurassic through mid cretaceous age in europe north america and east asia present evidence suggests that small gregarious dinosaurian bipeds included both theropod and ornithopod species

tracks and trackways of myotragus balearicus bate artiodactyla caprinae in pleistocene aeolianites from mallorca balearic islands western mediterranean tracks and trackways of the ruminant goat myotragus balearicus bate 1909 are abundant in the late pleistocene aeolianites of the south coast of mallorca spain the carbonate aeolianites form impressive dunes and related sand ramps that were initiated as echo dunes in front of a 20 40 m high paleocliff of miocene reefal limestone where the dunes built up to the cliff top they covered it as an aeolian ramp the dunes and sand ramps were active during the dry summer months but were passive during the wet winter period the small goat like animals were abundant on the island and for unknown reasons crossed the aeolian accumulations in large numbers this study deals with the tracks formed in the dune deposits all preserved trackways indicate impression into moist sand special features of the tracks include the structure produced by the withdrawal of the foot here called the axis and a disturbance zone of plastic deformation around this on dune crests the disturbance zone surrounds the axis more or less symmetrically however in addition a pressure pad of dislocated slightly rotated sediment bound by curved microfaults is commonly produced posterior to the axis by propulsive pressure of the foot on steep stoss and lee slopes the pressure pad becomes oriented in a down slope position as a result of gravitational slip of the walking animal combination of disturbance of the sediment in this way by manus followed by overprinting of similar disturbance by pes produces highly complicated track structure this structure may be characteristic of artiodactylous mammals in soft sand particularly aeolian deposits the structure is designated as bifidipes aeolis isp nov