three dimensional splay fault geometry and implications for tsunami generation megasplay faults very long thrust faults that rise from the subduction plate boundary megathrust and intersect the sea floor at the landward edge of the accretionary prism are thought to play a role in tsunami genesis we imaged a megasplay thrust system along the nankai trough in three dimensions which allowed us to map the splay fault geometry and its lateral continuity the megasplay is continuous from the main plate interface fault upwards to the sea floor where it cuts older thrust slices of the frontal accretionary prism the thrust geometry and evidence of large scale slumping of surficial sediments show that the fault is active and that the activity has evolved toward the landward direction with time contrary to the usual seaward progression of accretionary thrusts the megasplay fault has progressively steepened substantially increasing the potential for vertical uplift of the sea floor with slip we conclude that slip on the megasplay fault most likely contributed to generating devastating historic tsunamis such as the 1944 moment magnitude 8 1 tonankai event and it is this geometry that makes this margin and others like it particularly prone to tsunami genesis

single crystal 40ar 39ar dating of the olorgesailie formation southern kenya rift single crystal laser fusion sup 40 ar sup 39 ar analyses and several conventional bulk fusion sup 40 k sup 40 ar dates have been used to determine the age of volcaniclastic strata within the olorgesailie formation and of associated volcanic and sedimentary units of the southern kenya rift in the principal exposures along the southern edge of the legemunge plain the formation spans the interval from approximately 500 to 1 000 ka deposition continued to the east along the ol keju nyiro river where a tuff near the top of the formation has been dated at 215 ka in these exposures the formation is unconformably overlain by sediments dated at 49 ka a possible source for the olorgesailie tephra the ol doinyo nyokie volcanic complex contains as ash flow dated at approximately 1 ma extending the known age range of this complex to encompass that of virtually the entire olorgesailie formation in the legemunge plain these geologic examples illustrate the importance of the single crystal sup 40 ar sup 39 ar dating technique whereby contaminant altered or otherwise aberrant grains can be identified and eliminated from the determination of eruptive ages for reworked or altered pyroclastic deposits the authors have presented a computer modeling procedure based on an inverse isochron analysis thatmore promotes a more objective approach to trimming sup 40 ar sup 39 ar isotope data sets of this type less

deep crustal reflections from a vibroseis survey in northern switzerland abstract in 1982 a vibroseis survey comprising 180 km of reflection profiles was run in northern switzerland in order to investigate the suitability of the crystalline basement for the deposition of highly radioactive waste a configuration was chosen with 144 channels 25 m of geophone spacing 20 s sweeps ranging from 11 to 61 hz and stacking of 4 or 8 sweeps of 3 simultaneous vibrators at twice the geophone spacing the listening time was generally 4 s and at 4 sites it was extended to 11s for the detection of deeper crustal reflectors this survey unravelled the complicated fault and thrust system beneath the swiss folded jura mountains the stack from 4 s to 11 s reveals clearly a strong sloping reflector between 3 0 and 3 5 s which is strong evidence for a pronounced differentiation in the upper crust a series of reflections is observed between 5 8 and 7 2 s the top of which can be correlated with the conrad discontinuity a strong layered signal between 9 0 and 9 5 s is interpreted as reflections from the m discontinuity the main features are compatible with results from nearby refraction surveys in the southern rhinegraben rift system which show a distinct velocity increase of about 0 5 km s in the lower crust at a depth ranging from 15 to 20 km followed by an inversion zone or a laminated structure before reaching the moho at about 27 km depth the correlation of the field recordings with the first 10 s of the up sweep only shows some loss of resolution in the uppermost 3 s because of the lower frequency content of the signal however the lower parts of the sections are nearly identical the fact that the deeper reflectors in the sections can consistently be traced laterally is a strong argument for using this processing technique thus high coverage vibroseis surveys utilizing up sweep can be processed for deep crustal reflections even if the recording time is restricted to the standard 4 s provided the surface static corrections are carried out with high precision

an energy duration procedure for rapid determination of earthquake magnitude and tsunamigenic potential summary we introduce a rapid and robust energy duration procedure based on the haskell extended source model to obtain an earthquake moment and a moment magnitude med using seismograms at teleseismic distances 30 90 this procedure combines radiated seismic energy measures on the p to s interval of broadband signals and source duration measures on high frequency p wave signals the med energy duration magnitude is scaled to correspond to the global centroid moment tensor cmt moment magnitude mcmtw and can be calculated within about 20 min or less after origin time ot the measured energy and duration values also provide the energy to moment ratio used for identification of tsunami earthquakes the med magnitudes for a set of recent large earthquakes match closely mcmtw even for the largest great earthquakes these results imply that the med measure is accurate and does not saturate after the 2004 december 26 sumatra andaman mega thrust earthquake magnitude estimates available within 1 hr of ot ranged from m 8 0 to 8 5 the cmt magnitude available about 3 hr after ot was mcmtw 9 0 and several months after the event mw 9 1 9 3 was obtained from analysis of the earth normal modes the energy duration magnitude for this event is med 9 2 a measure that is potentially available within 20 min after ot after the 2006 july 17 java earthquake the magnitude was evaluated at m 7 2 at 17 min after ot the cmt magnitude available about 1 hr after ot was mcmtw 7 7 the energy duration results for this event give med 7 8 with a very long source duration of about 160 s and a very low value indicating a possible tsunami earthquake

combined seismic reflection and refraction profiling in southwest germany detailed velocity mapping by the refraction survey summary within the framework of site survey studies of the deep drilling program of the federal republic of germany ktb coincident deep seismic reflection and refraction experiments in the black forest southwest germany were carried out the simultaneous interpretation of the reflection and the refraction data reveals in particular both a strong velocity reduction in the upper crust and a laterally varying laminated structure of the lower crust additional refraction lines result in a three dimensional crustal model which shows two distinct crustal types of different seismic properties these crustal types seem to correlate with the major geologic units of southwest germany variations of poisson s ratio derived from clearly recorded shear wave data show a similar trend

synthetic seismograms for a complex crustal model the algorithm of the original reflectivity method has been vectorized and implemented on a cdc cyber 205 computer calculation times are shortened by a factor of 20 to 30 compared with a general purpose computer with a capacity of several million floating point operations per second mflop the rapid calculation of synthetic seismograms for complex models high frequency sources and all offset ranges is a provision for modeling not only particular phases but the whole observed wavefield as an example we model refraction data of the black forest southwest germany and are able to derive rather tight constraints on the physical properties of the lower crust

effect of variable bathymetry on the amplitude of teleseismic tsunamis a ray tracing experiment we apply surface wave ray tracing techniques to tsunami propagation in an ocean of variable depth because tsunami velocities are proportional to the square root of the depth of the water column the juxtaposition of oceanic plateaux and basins generates strong lateral velocity gradients and bathymetric features can act as lenses focusing or defocusing the tsunami waves we present a reconstruction of the tsunami wave field from the great chilean earthquake of 1960 an order of magnitude computation based on the concept of ray density provides qualitative agreement with observations at several sites in the pacific ocean we also demonstrate the possibility of using reciprocal maps to identify tsunamigenic zones that present particular danger for a given receiving shore

the geochronological potential of isoleucine epimerisation in cassowary and megapode eggshells from archaeological sites abstract our research demonstrates that the extent of isoleucine epimerisation a i in fragments of avian eggshells provides geochronological information in archaeological contexts in the archaeological sequence of hay cave northern queensland australia there is an excellent correspondence between the a i values of australian brush turkey alectura lathami eggshells n 99 and independent geochronological control n 16 radiocarbon ages including 4 on eggshell calcite the a i values identify three phases of deposition during the holocene at hay cave in contrast to the alectura eggshell a i values a poor correspondence was observed between the a i values of cassowary casuarius eggshells from toe n 35 and kria caves n 23 ayamaru plateau papua and the depths from which the specimens were recovered in these stratified sequences given coherent archaeofauna trends and radiocarbon chronologies n 8 and 2 eggshell calcite radiocarbon ages at toe and kria respectively with respect to depth the variable a i values are not explicable in terms of mixing rather the variability is most likely due to exposure of the eggshells to the high temperatures of campfires despite the variability eggshells with relatively low a i values amongst specimens recovered from similar depths and therefore presumably least influenced by high temperatures exhibit a gradual increase in a i with respect to depth as expected in a stratified deposit from this observation it is suggested that the identification of heated eggshells will increase confidence in geochronological information provided by a i these studies illustrate the complications that arise from campfire induced acceleration of amino acid racemisation and emphasise that although this phenomenon is common it is not universally encountered in archaeological contexts

moment tensor inversion of small earthquakes in southwestern germany for the fault plane solution summary the amplitudes of direct p and s waves as well as p and other deep crustal body wave phases from events in southwestern germany are studied for the effects of the double couple earthquake radiation pattern the direct p and s wave amplitudes for six earthquakes in the southern black forest of west germany with magnitudes between 2 2 and 0 5 were inverted for the source moment tensor and the double couple components were extracted from the solutions and refined by a further inversion the inversion focal mechanisms using both p and s wave amplitudes were quite consistent with those found from a large set of first motion readings even when very different crustal models were used for the events at or above magnitude 1 4 inversions using only direct p wave amplitudes also yielded good focal mechanisms furthermore the vertical component record at a station at p distance from the largest of the events was successfully synthesized using local mechanisms representative of those found from the inversions the phases modelled included p pmp and several free surface reflections the effect of the earthquake radiation pattern was also noted in the amplitudes of the p arrivals of a set of azimuthally distributed stations for two other earthquakes this study confirms that direct p and s amplitudes can be inverted for the source focal mechanism and suggests that deeper crustal phases like p pmp etc are also affected by the earthquake radiation pattern

crustal evolution of the rhinegraben area 1 exploring the lower crust in the rhinegraben rift by unified geophysical experiments abstract unified geophysical investigations of the lithosphere in the rhinegraben rift system have revealed new details of the lower crust and its role in the rifting process the new findings allow an assessment of the compatibility of four different geophysical notions and properties of the lower crust 1 1 the lower crust as the layer beneath the conrad discontinuity with a p wave velocity of about 6 5 km s or greater refraction seismics 2 2 the laminated band of reflections as seen in the near vertical reflection seismic experiments in many parts of the continents 3 3 the ductile part of the crust below the brittle ductile transition devoid of earthquakes in seismically active regions 4 4 the electrical conductivity of the lower crust indicative of dry or wet conditions or still unknown conduction phenomena in the rhinegraben area the lamination of the lower crust serves as an outstanding marker of deep tectonic activity during the rifting process in which the crust of the rhinegraben rift system has been subjected to three different natural dynamic processes 1 uplift by 2 to 3 km with subsequent erosion of the rhinegraben shoulders black forest and vosges mountains caused decompression possibly leading to the formation of a low velocity high electrical conductivity zone right on top of the laminated lower crust beneath the elevated shoulders of the black forest 2 the brittle crystalline wedge of the graben proper subsided nearly undeformed into the lower crust which became about 5 to 7 km thinner below the graben than below the shoulders 3 the deepest hypocentres in the black forest dinkelberg area if projected onto the neighbouring reflection profile would be located 7 to 8 km within the laminated lower crust beneath the southern black forest indicating a discrepancy between the top of the lower crust as defined by the brittle ductile transition as seen by the deepest earthquakes and by the top of the laminated reflection band the rhinegraben rift system reveals the properties and behaviour of the lower crust under a wide variety of tectonic situations

source inversion of w phase speeding up seismic tsunami warning w phase is a long period phase arriving before s wave it can be interpreted as superposition of the fundamental first second and third overtones of spheroidal modes or rayleigh waves and has a group velocity from 4 5 to 9 km s 1 over a period range of 100 1000 s the amplitude of long period waves better represents the tsunami potential of an earthquake because of the fast group velocity of w phase most of w phase energy is contained within a short time window after the arrival of the p wave at a distance of 50 w phase energy is contained within 23 min after the origin time which is the distinct advantage of using w phase for rapid tsunami warning purposes we use a time domain deconvolution method to extract w phases from the broad band records of global seismic networks the bandwidth of w phase is approximately from 0 001 to 0 01 hz and we bandpass filter the data from 0 001 to 0 005 hz in most cases having extracted w phase from the vertical component records we perform a linear inversion using a point source to determine mw and the source mechanism for several large earthquakes including the 2004 sumatra andaman earthquake the 2005 nias earthquake the 2006 kuril is earthquake and the 2007 sumatra earthquake w phase inversion yields reliable solutions and holds promise of the use of w phase for rapid assessment of tsunami potential

molecular organic matter in speleothems and its potential as an environmental proxy abstract organic matter preserved in speleothems has considerable potential to record changes in the surrounding environment particularly in the overlying vegetation here we review three types of organic matter analysis relevant to speleothems organic fluorescence lipid biomarker analysis and amino acid racemisation organic matter luminescence provides a useful non destructive and rapid method for assessing dissolved organic matter quantity and quality while biomarker analysis amino acids and lipids has the potential to provide a more detailed signal related to specific parts of the surrounding ecosystem such as the dominant vegetation regime and bacterial activity amino acid analysis has yet to prove demonstrably useful in stalagmites due to the inability to characterise the sources of proteinaceous matter however the small but increasing body of work on lipid biomarker analysis in stalagmites has shown that a wide variety of recognisable biomarkers are preserved over long periods of time 100 ka can be recovered at temporal resolutions of

assessing amino acid racemization variability in coral intra crystalline protein for geochronological applications over 500 free amino acid faa and corresponding total hydrolysed amino acid thaa analyses were completed from eight independently dated multi century coral cores of massive porites sp colonies this dataset allows us to re evaluate the application of amino acid racemization aar for dating late holocene coral material 20 years after goodfriend et al gca56 1992 3847 first showed aar had promise for developing chronologies in coral cores this re assessment incorporates recent method improvements including measurement by rp hplc new quality control approaches e g sampling and sub sampling protocols statistically based data screening criteria and cleaning steps to isolate the intra crystalline skeletal protein we show that the removal of the extra crystalline contaminants and matrix protein is the most critical step for reproducible results and recommend a protocol of bleaching samples in naocl for 48 h to maximise removal of open system proteins while minimising the induced racemization we demonstrate that aar follows closed system behaviour in the intra crystalline fraction of the coral skeletal proteins our study is the first to assess the natural variability in intra crystalline aar between colonies and we use coral cores taken from the great barrier reef australia and jarvis island in the equatorial pacific to explore variability associated with different environmental conditions and thermal histories chronologies were developed from thaa asx d l ala d l glx d l and faa asx d l for each core and least squares monte carlo modelling applied in order to quantify uncertainty of aar age determinations and assess the level of dating resolution possible over the last 5 centuries aar within colonies follow consistent stratigraphic aging however there are systematic differences in rates between the colonies which would preclude direct comparison from one colony to another for accurate age estimation when aar age models are developed from a combined dataset to include this natural inter colony variability thaa asx d l glx d l and ala d l give a 2 age uncertainty of 19 38 and 29 year for the 20th c respectively in comparison 2 age uncertainties from a single colony are 12 12 and 14 year this is the first demonstration of faa d l for dating coral and following strict protocols 2 precisions of 24 years can be achieved across different colonies in samples from the last 150 years and can be 10 years within a core from a single colony despite these relatively large error estimates aar would be a valuable tool in situations where a large number of samples need to be screened rapidly and cheaply e g identifying material from mixed populations in beach or uplift deposits prior to and complementing the more time consuming geochronological tools of u th or seasonal isotopic timeseries

a review of amino acid racemization studies in quaternary mollusks stratigraphic and chronologic applications in coastal and interglacial sites pacific and atlantic coasts united states united kingdom baffin island and tropical islands abstract amino acid racemization aar studies of quaternary mollusks mostly marine mollusks from coastal deposits are reviewed data obtained in regional studies from the u s atlantic and pacific coasts baffin island the united kingdom and tropical islands are discussed as they relate to method evaluation kinetic model development and aminostratigraphic applications u s pacific coast studies have been employed for estimating tectonic deformation rates study of molluscan zonation patterns in the late pleistocene and in kinetic model evaluation u s atlantic coast studies have identified multiple aminostratigraphic zones in areas with complex morphostratigraphic relationships and have also revealed some important conflicts between aminostratigraphic temperature concepts and radiometric data studies in the united kingdom involving coastal sites and non marine interglacial sites identify some stratigraphic and kinetic conflicts but provide a preliminary chronostratigraphic model for the classical interglacial terminology of the u k middle to late pleistocene baffin island studies involving aar data and u th dating of shells have resulted in some significant revisions of previous chronologic models the arctic environment has also stimulated some novel approaches in the collection and interpretation of aar results tropical island studies though few in number aid in calibration of observed racemization and also aid in correlation of coastal deposits with late pleistocene isotopic ice volume records

geoarchaeology at gi a middle stone age and later stone age site in the northwest kalahari abstract gi with sealed middle stone age and later stone age occurrences is located in the dobe valley along the botswana namibia border the phases of middle stone age settlement were linked to a semiarid streamway during the early upper pleistocene a major humid interval followed when a large lake was ponded in the dobe valley later stone age settlement appeared after this lake disappeared and was replaced by a mosaic of pans ephemeral lakes subsequently another period of humid environment favoured another valley wide lake during the late upper pleistocene later stone age settlement resumed when this second lake deteriorated into the modern pan terrains of the dobe valley in total the gi beds record multiple environmental changes both more humid and more arid than present during the upper pleistocene and holocene as well as a variable array of adaptive opportunities for prehistoric settlement

rapid estimation of rupture extent for large earthquakes application to the 2004 m9 sumatra andaman mega thrust 1 rapid estimation of the rupture extent of large earthquakes is critical for tsunami warning and emergency response the hypocenter of a distant earthquake is determined from the first seismic p waves within about 15 minutes after the event however methods for determining the size and rupture extent of very large earthquakes rely on long period recordings and aftershock locations which are not available until several hours or more after the event here we introduce a method for rapid estimation of the rupture termination location for large earthquakes based on short period p wave recordings available about 30 minutes after an event the hypocenter and the rupture termination location provide estimates of the extent of rupture and the event size application to the 2004 m9 sumatra andaman earthquake gives a rupture termination location near the andaman islands about 1100 km north of the hypocenter and a rupture duration of about 8 minutes

mechanism of the 1992 nicaragua tsunami earthquake the 1992 nicaragua earthquake generated larger tsunamis than expected from its surface wave magnitude ms 7 2 and is known as a tsunami earthquake seismological studies showed that the duration was very long for its size about 100 s other studies have shown that the seismic moment estimated from tsunamis is an order of magnitude larger than that from seismic waves even after the long duration is accounted for numerical computations of tsunamis from various fault models are made to reconcile this discrepancy comparison of calculated waveforms with tide gauge records shows that the fault width is 40 km much narrower than the aftershock area and extends only into the upper 10 km of the ocean bottom slip amount on the fault is estimated to be 3 m from amplitude comparisons the fault length is estimated to be 250 km slightly longer than the aftershock area from comparison of the tsunami height distribution the rigidity around the shallow fault may be smaller than that of a standard underthrust fault and the seismic moment is estimated as 3 1020 nm consistent with the seismic observations a slow rupture on the shallow fault presumably in the subducted sediments is responsible to the unusually large tsunami excitation

tsunami early warning within five minutes tsunamis are most destructive at near to regional distances arriving within 20 30 min after a causative earthquake effective early warning at these distances requires notification within 15 min or less the size and impact of a tsunami also depend on sea floor displacement which is related to the length l width w mean slip d and depth z of the earthquake rupture currently the primary seismic discriminant for tsunami potential is the centroid moment tensor magnitude m w cmt representing the product lwd and estimated via an indirect inversion procedure however the obtained m w cmt and the implied lwd value vary with rupture depth earth model and other factors and are only available 20 30 min or more after an earthquake the use of more direct discriminants for tsunami potential could avoid these problems and aid in effective early warning especially for near to regional distances previously we presented a direct procedure for rapid assessment of earthquake tsunami potential using two simple measurements on p wave seismograms the predominant period on velocity records t d and the likelihood t 50 ex that the high frequency apparent rupture duration t 0 exceeds 50 55 s we have shown that t d and t 0 are related to the critical rupture parameters l w d and z and that either of the period duration products t d t 0 or t d t 50 ex gives more information on tsunami impact and size than m w cmt m wp and other currently used discriminants these results imply that tsunami potential is not directly related to the product lwd from the seismic faulting model as is assumed with the use of the m w cmt discriminant instead information on rupture length l and depth z as provided by t d t 0 or t d t 50 ex can constrain well the tsunami potential of an earthquake we introduce here special treatment of the signal around the s arrival at close stations a modified real time m wpd rt magnitude and other procedures to enable early estimation of event parameters and tsunami discriminants we show that with real time data currently available in most regions of tsunami hazard event locations m b and m wp magnitudes and the direct period duration discriminant t d t 50 ex can be determined within 5 min after an earthquake occurs and t 0 t d t 0 and m wpd rt within approximately 10 min this processing is implemented and running continuously in real time within the early est earthquake monitor at ingv rome http early est rm ingv it we also show that the difference m b log10 t d t 0 forms a rapid discriminant for slow tsunami earthquakes the rapid availability of these measurements can aid in faster and more reliable tsunami early warning for near to regional distances

effect of depth dependent shear modulus on tsunami generation along subduction zones estimates of the initial size of tsunamis generated by subduction zone earthquakes are significantly affected by the choice of shear modulus at shallow depths analysis of over 360 circum pacific subduction zone earthquakes indicates that for a given seismic moment source duration increases significantly with decreasing depth bilek and lay 1998 1999 under the assumption that stress drop is constant the increase of source duration is explained by a 5 fold reduction of shear modulus from depths of 20 km to 5 km this much lower value of shear modulus at shallow depths in comparison to standard earth models has the effect of increasing the amount of slip estimated from seismic moment determinations thereby increasing tsunami amplitude the effect of using depth dependent shear modulus values is tested by modeling the tsunami from the 1992 nicaraguan tsunami earthquake using a previously determined moment distribution ihmle 1996a we find that the tide gauge record of this tsunami is well matched by synthetics created using the depth dependent shear modulus and moment distribution because excitation of seismic waves also depends on elastic heterogeneity it is important particularly for the inversion of short period waves that a consistent seismic tsunami shear modulus model be used for calculating slip distributions

introduction to historical and recent catastrophic tsunamis in the world volume ii tsunamis from 1755 to 2010 eighteen papers on past and recent destructive tsunamis are included in volume ii of the pageoph topical issue historical and recent catastrophic tsunamis in the world three papers discuss deep sea dart and coastal tsunami observations warning systems and risk management in the pacific ocean four papers examine the 1755 lisbon 1964 alaska 2003 algeria and 2011 haiti tsunamis four more papers as well as some papers in volume i report on various aspects of the 2010 chile tsunami two papers present some results of field survey and modelling investigation of the 2010 mentawai indonesia tsunami three papers report on modelling efforts of tsunami generation by earthquake and landslide and of tsunami propagation finally two papers discuss hazard assessment using a probabilistic approach

recently formed elastic anisotropy and petrological models for the continental subcrustal lithosphere in southern germany this paper advances new evidence for elastic anisotropy in the continental subcrustal lithosphere in southern germany the range of petrological models compatible with the observed azimuthal variation of seismic p wave velocity is explored the azimuthal distribution of amplitudes of mantle phases and the observed increase of p velocity with depth both indicate a continuation of anisotropy with depth together with an increase of preferred orientation even depletion of the upper mantle in basaltic components as suggested by mantle xenoliths from various parts of germany cannot explain the velocity depth and azimuthal amplitude observations without an increase of anisotropy with depth preferred orientation of olivine is the most likely mechanism for the observed phenomena its fast a axis at the moho level is directed towards n22 5 e the b axis is also required to be horizontal i e the b plane one of the preferred glide planes of olivine is vertical with a strike of n22 5 e therefore this preferred glide plane of olivine practically coincides with the plane of maximum horizontal shear stress deduced from fault plane solutions of earthquakes in western germany this is a strong indication that the preferred orientation of olivine is formed in the recent west european crustal stress field leaking into the upper mantle the distribution of velocities to a depth of at least 50 km requires slight horizontal rotation of the a axis with depth by 10 towards n32 e and a change in the modal composition towards a depletion increasing with depth compatible with the composition of mantle xenoliths from western germany further experiments are needed to substantiate this suggestion which could lead to a better understanding of the interaction of crustal and upper mantle stress strain fields

the complexity of the crust and moho under the southeastern superior and grenville provinces of the canadian shield from seismic refraction wide angle reflection data the major features of the individual velocity models poisson s ratio values and crustal complexity derived from the interpretation of seismic data sets from four long range seismic refraction wide angle reflection experiments are summarized the experiments were conducted from 1982 92 in the southeastern portion of the canadian shield in the conventional analysis of seismic refraction wide angle reflection data only the onset times and amplitudes of the major arrival phases are used to derive seismic velocity models of the region under study these models are over smoothed have a number of intermediate discontinuities are unable to explain the pg coda and bear very little resemblance to the models derived from the analysis of near vertical seismic reflection data in this paper some of the differences between seismic models derived from near vertical reflection analysis and those from refraction analysis are reconciled from an analysis of the wide angle reflection fields of the crustal coda wav

a last interglacial fauna from the eastern sahara abstract recent work on the middle paleolithic at bir tarfawi in the hyperarid eastern sahara

racemization derived late devensian temperature reduction in scotland we report here that shells of the marine bivalve mollusc arctica islandica collected near king edward scotland yield isoleucine epimerization d l ratios only slightly higher than ratios in late glacial specimens of the same taxon collected from nearby sites we have determined the ages of two of the king edward shells by tandem accelerator mass spectrometry tams radiocarbon dating to be 40kyr from the difference in d l ratios we calculate the average temperature depression during the last glaciation to have been 9 c below holocene temperatures

seismic velocities and anisotropy of the lower continental crust a review seismic anisotropy is often neglected in seismic studies of the earth s crust since anisotropy is a common property of many typically deep crustal rocks its potential contribution to solving questions of the deep crust is evaluated the anisotropic seismic velocities obtained from laboratory measurements can be verified by computations based on the elastic constants and on numerical data pertaining to the texture of rock forming minerals for typical lower crustal rocks the influence of layering is significantly less important than the influence of rock texture surprisingly most natural lower crustal rocks show a hexagonal type of anisotropy maximum anisotropy is observed for rocks with a high content of aligned mica it seems possible to distinguish between layered intrusives and metasediments on the basis of in situ measurements of anisotropy which can thus be used to validate different scenarios of crustal evolution

the seismic reflection character of the continental mohorovicic discontinuity the continental mohorovicic discontinuity is most often interpreted as a step function velocity boundary however on deep crustal seismic reflection profiles reflections at depths where refraction data places the moho have laminated character and are laterally discontinuous these observations on continental reflection data point to a model of the moho that has thin layered rather than block structure previous workers who have synthetically generated seismic responses from various crust mantle boundary models have shown that thin layered models of alternating high and low velocity generate responses that best emulate observed moho arrivals geologic interpretations of the thin layering include relatively undeformed metasediments cumulate layering tectonic banding and lenses of partial melt to obtain more direct geologic evidence a synthetic seismogram is generated from geologic cross sections of the ivrea verbano zone an exposed section through the lower crust and upper mantle the synthetic shows laminations similar to those observed on reflection data without more direct evidence no single geologic interpretation of the moho is reasonable indeed the moho may be a laterally variable boundary its composition and structure dependent upon the geologic history of the overlying crust

a middle stone age paleoscape near the pinnacle point caves vleesbaai south africa abstract open air middle stone age msa contexts in southern africa have received relatively little research attention compared to caves rock shelters msa caves rock shelters can provide long sequences of msa behaviors dominated by residential activities in circumscribed contexts but most procurement activities occurred on the landscape in uncircumscribed space we have a limited understanding of these activities at present making studies of open air sites crucial to alleviate this bias the south african coast paleoclimate paleoenvironment paleoecology paleoanthropology sacp4 project expanded its research scope to include msa archaeology from open air contexts we report on a series of msa open air assemblages that are exposed on ancient land surfaces suggestive of intact paleosols at vleesbaai and visbaai south africa importantly these sites occur in close proximity to the long cave rock shelter sequences at pinnacle point this presents the novel potential to study evidence of msa behavior in closed and open settings where their proximity to each other approximates the typical hunter gatherer daily foraging radius documented in ethnography we present a fabric and technological analysis of msa stone tool assemblages from three areas analysis of total station piece plotting of artifact bearing plunge suggests that the lithic assemblages have undergone limited post depositional disturbance the technological analysis and exploratory comparisons between these open air assemblages and msa cave and rock shelter contexts at pinnacle point cave 13b and 9 and cape st blaize cave suggest that the quartzite artifacts from vleesbaai were procured from locally available sources and may have been field processed there before being transported elsewhere perhaps to the caves rock shelters further the analysis suggests a dichotomous pattern of retouched tool discard where quartzite tools are discarded similarly across the landscape in contrast non quartzite tools may have been made primarily at the cave sites and discarded or lost more frequently on the landscape

amino acid geochronology its impact on our understanding of the quaternary stratigraphy of the british isles this review aims to act as a brief primer to amino acid racemization and protein breakdown as well as to document the major applications and results of amino acid dating on british quaternary sediments amino acid results from fossil shells have had far reaching effects in developing our current understanding of british quaternary stratigraphy and its links to continental europe and the marine record to appreciate the potential for amino acid geochronology the technique s limitations and recent developments are discussed as well as the future of the field copyright 2009 john wiley sons ltd

paleoecological reconstructions in southern egypt based on the stable carbon and nitrogen isotopes in the organic fraction and stable carbon isotopes in individual amino acids of fossil ostrich eggshell previous studies on ostrich eggshell oes have demonstrated the remarkable integrity of this medium for the retention of indigenous proteinaceous residues over 106 yr and more e g brooks et al 1990 miller et al 1992 such integrity suggests that the initial isotopic composition of the organic molecules might also be retained and the stable isotopes of carbon t 3 c and nitrogen 15n in various organic fractions including fil3c in individual amino acids might be used to provide some information about the ecology at the time the egg was formed carbon isotopes in the organic and inorganic fractions of bones and teeth from herbivores are reasonably well established indices of the relative proportions of c3 and ca plants consumed e g van der merwe 1982 deniro 1987 van der merwe et al 1988 c3 plants mean 13c 26 5 2 o o leary 1981 include all trees and most shrubs and grasses adapted to temperate or shaded tropical forests ca plants mean 3 c 12 5 lo oo o leary 1981 include most tropical grasses and a few shrubs adapted to high temperatures and radiation based on these observations general paleoecological interpretations can often be made from the

coincident seismic reflection refraction studies of the continental lithosphere a global review nearly 50 coincident seismic reflection refraction studies to depths of at least the moho provide an improved understanding of the continental lithosphere some conclusions include the following 1 a transparent upper crust a common observation on vertical reflection profiles cannot generally be correlated with velocity gradients or low velocity zones rather a commonly transparent upper crust may be explained by short wavelength steeply dipping features in the brittle upper crust and to a lesser degree by signal contamination from source generated noise 2 the reflective lower crust in extensional terranes appears to be characterized by a high average seismic velocity 6 6 7 3 km s and to consist of laminated high and low velocity layers with typical thicknesses of 100 200 m 3 landward dipping reflectors observed in the middle to lower crusts of convergent zones have been identified as paired high and low velocity slabs which represent oceanic crust and mantle accreted via underplating to the continental margin 4 the crust mantle boundary may differ sufficiently when imaged with vertical incidence and wide angle data to justify the retention for the present of the concept of separate reflection and refraction mohos while there is good evidence that these features are coincident within measurement uncertainties in most regions recently recorded data from the basin and range admit the possibility for noncoincidence in that area 5 upper mantle reflections which cannot be migrated into the lower crust remain rare despite isolated unequivocal examples thus the upper mantle appears to be relatively homogeneous at seismic reflection wavelengths and to lack the laminations inferred for the lower crust the wide angle method will likely provide the most reliable information on the velocity structure and physical state of this portion of the lithosphere for some years to come 6 there appear to be clear and consistent basic differences between convergent and extensional terranes which have been identified from coincident experiments these differences may be sufficiently universal to infer the tectonic history of poorly exposed terranes 7 no truly three dimensional coincident experiment i e including three dimensional migration has been conducted but some three dimensional data have been collected using both methods measurements of attenuation poisson s ratio and anisotropy within the crust using coincident data sets remain frontiers

teleseismic estimates of radiated seismic energy the e m 0 discriminant for tsunami earthquakes we adapt the formalism of boatwright and choy for the computation of radiated seismic energy from broadband records at teleseismic distances to the real time situation when neither the depth nor the focal geometry of the source is known accurately the analysis of a large data set of more than 500 records from 52 large recent earthquakes shows that this procedure yields values of the estimated energy ee in good agreement with values computed from available source parameters for example as published by the national earthquake information center neic the average logarithmic residual being only 0 26 units we analyze the energy to moment ratio by defining log10 ee m0 for regular earthquakes this parameter agrees well with values expected from theoretical models and from the worldwide neic catalogue there is a one to one correspondence between values of that are deficient by one full unit or more and the so called tsunami earthquakes previously identified in the literature as having exceedingly slow sources and believed due to the presence of sedimentary structures in the fault zone our formalism can be applied to single station measurements and its coupling to automated real time measurements of the seismic moment using the mantle magnitude mm should significantly improve real time tsunami warning

amino acid racemization dating of marine shells a mound of possibilities shell middens are one of the most important and widespread indicators for human exploitation of marine resources and occupation of coastal environments establishing an accurate and reliable chronology for these deposits has fundamental implications for understanding the patterns of human evolution and dispersal this paper explores the potential application of a new methodology of amino acid racemization aar dating of shell middens and describes a simple protocol to test the suitability of different molluscan species this protocol provides a preliminary test for the presence of an intracrystalline fraction of proteins by bleaching experiments and subsequent heating at high temperature checking the closed system behaviour of this fraction during diagenesis only species which pass both tests can be considered suitable for further studies to obtain reliable age information this amino acid geochronological technique is also applied to midden deposits at two latitudinal extremes northern scotland and the southern red sea results obtained in this study indicate that the application of this new method of aar dating of shells has the potential to aid the geochronological investigation of shell mounds in different areas of the world

rapid determination of mw from broadband p waveforms we analyze broadband seismograms for magnitude 5 to 7 earthquakes which occurred in and around japan to develop a technique to determine moment magnitude from first arrival p waveforms we theoretically consider displacements of the p wave portion on broadband seismograph record as an approximate source time function and integrate them to obtain scalar moments at each station we show that a combination of multiple records will give a good estimation of moment magnitude without correcting for the source mechanism this technique is quite simple and robust so it will be effective for a rapid evaluation of the tsunami potential of a large earthquake

a fast and simple diagnostic method for identifying tsunamigenic earthquakes an analysis of regional broadband seismograms of moderate and large subduction zone earthquakes in mexico shows that earthquakes which occur near the trench are abnormally depleted in high frequency radiation this observation leads to a simple and fast method to assess regional tsunami potential from earthquakes which occur along the pacific coast of mexico a significant advantage of the method is that a single broadband seismograph is sufficient for the purpose the method is based on the ratio of the total energy to the high frequency energy between 1 and 5 hz er computed from the seismograms for earthquakes with the same seismic moment er is an order of magnitude greater for a source area near the trench as compared to those near the coast the same seismograms are used to compute energy magnitude me which is tied to the moment magnitude mw a regional tsunami may be expected along the coast if me 6 5 and er corresponds to a source near the trench if however er corresponds to a near coast source then me may have to be greater than about 7 3 for a tsunami of similar size to occur along the coast the method holds promise for a fast regional tsunami warning in many pacific basin countries which lack an adequate seismic network

a rapid estimation of near field tsunami runup many efforts have been made to quickly estimate the maximum runup height of tsunamis associated with large earthquakes this is a difficult task because of the time it takes to construct an accurate tsunami model using real time data from the source it is possible to construct a database of potential seismic sources and their corresponding tsunami a priori however such models are generally based on uniform slip distributions and thus oversimplify the knowledge of the earthquake source here we show how to predict tsunami runup from any seismic source model using an analytic solution that is specifically designed for subduction zones with a well defined geometry i e chile japan nicaragua and alaska the main idea of this work is to provide a tool for emergency response trading off accuracy for speed the solutions we present for large earthquakes appear promising here runup models are computed for the following the 1992 mw 7 7 nicaragua earthquake the 2001 mw 8 4 peru earthquake the 2003 mw 8 3 hokkaido earthquake the 2007 mw 8 1 peru earthquake the 2010 mw 8 8 maule earthquake the 2011 mw 9 0 tohoku earthquake and the recent 2014 mw 8 2 iquique earthquake the maximum runup estimations are consistent with measurements made inland after each event with a peak of 9 m for nicaragua 8 m for peru 2001 32 m for maule 41 m for tohoku and 4 1 m for iquique considering recent advances made in the analysis of real time gps data and the ability to rapidly resolve the finiteness of a large earthquake close to existing gps networks it will be possible in the near future to perform these calculations within the first minutes after the occurrence of similar events thus such calculations will provide faster runup information than is available from existing uniform slip seismic source databases or past events of premodeled seismic sources

tsunami early warning using earthquake rupture duration and p wave dominant period the importance of length and depth of faulting summary after an earthquake rapid real time assessment of hazards such as ground shaking and tsunami potential is important for early warning and emergency response tsunami potential depends on seafloor displacement which is related to the length l width w mean slip d and depth z of earthquake rupture currently the primary discriminant for tsunami potential is the centroid moment tensor magnitude mcmtw representing the seismic potency lwd and estimated through an indirect inversion procedure the obtained mcmtw and the implied lwd value vary with the depth of faulting assumed earth model and other factors and is only available 30 min or more after an earthquake the use of more direct procedures for hazard assessment when available could avoid these problems and aid in effective early warning here we present a direct procedure for rapid assessment of earthquake tsunami potential using two simple measures on p wave seismograms the dominant period on the velocity records td and the likelihood that the high frequency apparent rupture duration t0 exceeds 50 55 s t0 can be related to the critical parameters l and z while td may be related to w d or z for a set of recent large earthquakes we show that the period duration product tdt0 gives more information on tsunami impact and size than mcmtw and other currently used discriminants all discriminants have difficulty in assessing the tsunami potential for oceanic strike slip and backarc or upper plate intraplate earthquake types our analysis and results suggest that tsunami potential is not directly related to the potency lwd from the seismic faulting model as is assumed with the use of the mcmtw discriminant instead knowledge of rupture length l and depth z alone can constrain well the tsunami potential of an earthquake with explicit determination of fault width w and slip d being of secondary importance with available real time seismogram data rapid calculation of the direct period duration discriminant can be completed within 6 10 min after an earthquake occurs and thus can aid in effective and reliable tsunami early warning

stratigraphy sedimentology chronology and palaeohydrology of quaternary lacustrine deposits at madigan gulf lake eyre south australia abstract madigan gulf is a large bay at the southern end of lake eyre north a major ephemerally flooded playa in arid central australia at the southwestern margin of a vast 1 300 000 km2 internal drainage basin the stratigraphy and chronology of the quaternary sequence in the gulf is described from 8 cores and a cliff exposure at the gulf margin a number of depositional environments are recognised and their distinctive sedimentary components are described facies recognised include deep and shallow water lacustrine environments dominated by surface water processes and dry or ephemerally flooded playa environments dominated by groundwater controlled processes sedimentary components include terrigenous clastics from river inflow and shoreline erosion carbonates of detrital inorganic or biological origin and gypsum and halite evaporites carbonates and gypsum evaporites precipitated within the basin are frequently reworked as clastic components the establishment of a preliminary chronology for the sequence by the application of thermoluminescence uranium thorium disequilibrium amino acid racemization and radiocarbon dating techniques has allowed a reconstruction of the last 130 ka of lake eyre palaeohydrology the wettest phase occurred during the last interglacial early in oxygen isotope stage 5 when an enlarged lake eyre was up to 25 m deep subsequently there has been a number of dry periods separating successively less effective wet phases culminating in the deposition of a substantial halite salt crust around the time of the glacial maximum the dry interludes are characterised by deflation of salts and sediment from the basin a process controlled by lowering of the watertable the record from madigan gulf demonstrates the dramatic and repetitive impact of lake deflation on the quaternary record of lake eyre in the early holocene a minor but mostly perennial lacustrine event was terminated at about 3 4 ka when the modern ephemeral playa regime was established the major catchment of lake eyre is located in the monsoon watered areas of northern australia as demonstrated by large floodings of the modern ephemeral regime major lacustrine episodes must indicate enhanced monsoon precipitation in northern australia in the holocene the lake has not risen to levels achieved during the early stage 5 lacustral phase indicating a marked reduction in the effectiveness of the monsoon in the present interglacial by comparison with its predecessor

disentangling the impacts of climate and human colonization on the flora and fauna of the australian arid zone over the past 100 ka using stable isotopes in avian eggshell abstract throughout the quaternary the flora and fauna of australia evolved and adapted to the high amplitude low and high frequency climate changes that characterized the ice age cycles however during the last glacial cycle between 120 and 15 ka unprecedented irreversible changes in flora and fauna occurred and in that same interval modern humans established their first firm presence in the landscape disentangling the impacts of the first order trend toward a colder drier planet through the late quaternary from the impacts of human colonization has been challenging from both the chronological and paleoenvironmental perspectives we utilize the stable isotopes of carbon and oxygen preserved in near continuous time series of dromaius emu eggshell from five regions across australia to provide independent reconstructions of ecosystem status and climate over the past 100 ka carbon isotopes are determined by the diet consumed by the female bird whereas oxygen isotopes record the status of local moisture balance in the months prior to breeding together 13 c and 18 o provide ecosystem status and climate from the same dated sample reducing correlation uncertainties between proxies combined with recent improvements in the chronologies of late quaternary shorelines fringing inland lake basins and deflation during arid times these data collectively reaffirm that australia generally became increasingly albeit irregularly drier from the last interglaciation through to the last glacial maximum dromaius eggshell 18 o documents peak aridity between 30 and 15 ka but shows no evidence of exceptional climate change between 60 and 40 ka in contrast dromaius 13 c diet documents an irreversible loss of the majority of palatable summer rainfall related c4 grasses across the australian arid zone between 50 and 45 ka about the same time that the giant megafaunal bird genyornis became extinct and coincident with human dispersal across the continent our data indicate that changes unique to australia occurred between 50 and 45 ka that led to a new climate vegetation relationship and an overall reduction in effective moisture across much of the continent the large summer rainfall dominated lakes of interior australia failed to re fill subsequently despite a wide range of global climate states a full explanation for the mechanisms behind these changes remains elusive but they are almost certainly related to human agency plausible explanations include a change in fire regime resulting from human lit fires a change in fire regime following extinction of megafaunal browsers and or a threshold response to increasing aridity of these the climate change explanation is least likely given the lack of evidence for unprecedented aridity between 60 and 40 ka and the successful adaptation of australian ecosystems to 2 5 ma of similar changes

cenozoic and mesozoic structure of the eastern basin and range province utah from cocorp seismic reflection data cocorp seismic reflection data collected from the eastern basin and range in west central utah provide information on cenozoic extensional tectonics mesozoic thrusting and their interrelationships those data show a series of remarkably continuous low angle reflectors that extend more than 120 km perpendicular to strike and can be traced as deep as 15 20 km over that distance none of these events are significantly cut by any high angle normal faults a major detachment beneath the sevier desert can be traced from a surface zone of normal faulting to a depth of 12 15 km with a regional apparent westward dip of 12 tentative correlation of upper and lower plate events suggests 30 60 km of extensional displacement on this detachment whether this structure is a reactivated mesozoic thrust is uncertain west steepening splays off the end of the detachment reach depths of 20 km and may represent a major mesozoic ramp or zones of distributed ductile shearing during extension some events are interpreted to be mesozoic thrusts of which at least one beneath the house range has been reactivated during the cenozoic the snake range decollement dips gently east and has a sense of cenozoic displacement opposite to that of other cenozoic detachments farther east deep events are most numerous beneath the east side of the sevier desert where they occur to depths of 30 km at the top of or perhaps partly within the anomalously low velocity upper mantle

dating lacustrine episodes in the eastern sahara by the epimerization of isoleucine in ostrich eggshells the eggshell of the african ostrich struthio camelus closely approximates a closed system for the retention of indigenous proteinaceous residues epimerization of the protein amino acid isoleucine follows linear first order kinetics in laboratory simulations nearly to racemic equilibrium and the variation in d l ratio within a single fragment or between fragments of the same age is significantly less than in other carbonate systems these observations suggest that the extent of isoleucine epimerization aile ile ratio in ostrich eggshell offers the potential for high resolution geochronology of quaternary deposits from the simulation experiments and dated early holocene samples for which we have in situ mean annual sediment temperature measurements arrhenius parameters have been calculated the activation energy is 30 33 kcal mol 1 similar to that of other carbonate systems we have measured the aile ile ratio in ostrich eggshell associated with lacustrine episodes at bir tarfawi and bir sahara east two depressions in what is currently the hyperarid eastern sahara the ratios can be used directly to indicate qualitatively the time represented by each series of lake sediment and to correlate disjunct lacustrine deposits within and between the basins uranium series disequilibrium dating of algal mats contained within some of the lake beds indicate that a major wet interval occurred about 130 ka ago using the u series date for calibration the amino acid ratios are used to date the most recent lacustrine interval to about 100 ka b p and two older intervals one about 200 25 ka b p and an older interval that occurred prior to 250 ka ago

chronology of the later stone age and food production in east africa abstract evidence from several archaeological sites in sub saharan africa suggests that the transition to modern human technology marked by the change from the middle to the later stone age lsa occurred first in east africa enkapune ya muto rockshelter in the central rift valley of kenya contains the oldest known archaeological horizons spanning this transition radiocarbon and obsidian hydration dates from this 5 6 m deep cultural sequence show that the later stone age began substantially earlier than 46 000 years ago ostrich eggshell beads were made 40 000 years ago early dates for the lsa and beads may have implications for the origin and dispersal of modern human behaviour and modern humans out of africa this site also contains the only known occurrences dating to the middle holocene dry phase in highland kenya and tanzania as well as occurrences that span the transition from hunting and gathering to food production and from the neolithic to the iron age the adoption of domestic animals by indigenous eburran hunter gatherers in highland east africa occurred gradually between 4900 and 3300 uncorrected radiocarbon years bp and the neolithic later iron age transition occurred around 1300 bp

amino acid age estimates quaternary atlantic coastal plain comparison with u series dates biostratigraphy and paleomagnetic control amino acid enantiomeric dl ratios in the mollusk mercenaria are compared with recently published biostratigraphic and or u series solitary coral data from 22 quaternary localities on the central and southern atlantic coastal plain in all cases local relative aminostratigraphic sequences are consistent with relative ages inferred from u series or biostratigraphic data although occasionally more depositional events are recognized by aminostratigraphic than biostratigraphic methods however if the u series data are used as age calibrations for the dl values latitudinal trends of isochronous dl values are highly variable and conflict with trends expected from the present temperature gradient which is smooth and nearly linear between 45 and 25 n age estimation can be performed independently of the u series data using a kinetic model that relies on the assumption that pleistocene temperature gradients have also been smooth functions of latitude although significantly steeper than the present temperature gradient within the uncertainties of this assumption kinetic model age estimates for localities in the coastal plain fall into the following groups 70 000 130 000 yr 200 250 000 yr 300 000 400 000 yr 500 000 600 000 yr 700 000 800 000 yr and 1 000 000 yr major conflicts between these model age estimates are observed for localities near charleston south carolina and in central virginia these conflicts could indicate that the basic temperature assumptions of aminostratigraphy are incorrect and that apparent local aminostratigraphic sequences clusters of different dl values could be due to factors other than age difference alternatively some of the u series dates may be only minimum ages for these localities

global seismicity of 2003 centroid moment tensor solutions for 1087 earthquakes abstract centroid moment tensor cmt solutions are presented for 1087 earthquakes that occurred during 2003 the solutions are obtained using the method of dziewonski et al dziewonski a m chou t a woodward j h 1981 determination of earthquake source parameters from waveform data for studies of global and regional seismicity j geophys res 86 2825 2852 and applying corrections for aspherical earth structure as represented by the whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward dziewonski a m woodward r l 1992 acoustic imaging at the planetary scale in emert h harjes h p eds acoustical imaging vol 19 plenum press new york pp 785 797 the model of inelastic attenuation of durek and ekstrom durek j j ekstrom g 1996 a radial model of inelasticity consistent with long period surface wave attenuation bull seism soc am 86 144 158 is used to predict the decay of the waveforms the focal mechanisms of the largest or otherwise significant earthquakes of 2003 are reviewed

the moho in the northern basin and range province nevada along the cocorp 40 n seismic reflection transect cocorp seismic reflection profiles across nevada at about 40 n image a prominent essentially continuous band of reflectors at a two way traveltime of 9 to 11 s the approximate correspondence of this reflection time with estimates of the two way traveltime to the moho in this area provided by seismic refraction data suggests that the prominent reflections are from the moho the relief on these reflectors the reflection moho beneath nevada across a latitudinal transect of

low latitude glacial cooling in the southern hemisphere from amino acid racemization in emu eggshells the record of natural climate variability over glacial interglacial timescales provides a framework from which a better mechanistic understanding of the climate system may be derived but this approach is limited by the number and distribution of well dated and reliable palaeoenvironmental archives particularly vexing is the conflicting evidence for low latitude cooling during the last glacial maximum and the apparent synchrony in glacial activity between the hemispheres despite out of phase insolation forcing1 4 here we utilize the temperature dependent amino acid racemization reaction in radiocarbon dated emu eggshell fragments from the continental interior of australia to reconstruct low altitude subtropical temperatures for the past 45 kyr racemization rate changes indicate that millennial scale average air temperatures were at least 9 c lower between 45 and 16 kyr bp than since 16 kyr bp a temperature change of this magnitude coupled with other low latitude palaeotemperature records that indicate substantial cooling3 4 must reflect global processes which we speculate involved glacial age reduction in atmospheric water vapour content

tsunami early warning using earthquake rupture duration 1 effective tsunami early warning for coastlines near a tsunamigenic earthquake requires notification within 5 15 minutes we have shown recently that tsunamigenic earthquakes have an apparent rupture duration t0 greater than about 50 s here we show that t0 gives more information on tsunami importance than moment magnitude mw and we introduce a procedure using seismograms recorded near an earthquake to rapidly determine if t0 is likely to exceed t 50 or 100 s we show that this duration exceedance procedure can be completed within 3 10 min after the earthquake occurs depending on station density and that it correctly identifies most recent earthquakes which produced large or devastating tsunamis this identification forms a complement to initial estimates of the location depth and magnitude of an earthquake to improve the reliability of tsunami early warning and in some cases may make possible such warning

seismic refraction investigation of the black forest abstract within the framework of site surveys of the deep continental drilling program ktb deep seismic sounding experiments were carried out in the black forest southwest germany in august 1984 these site surveys comprised seismic refraction as well as seismic reflection measurements this paper will concentrate on the interpretation of the refraction data which were observed along a 240 km long line approximately following the morphological axis of the black forest in a n s direction and extending in the south into the swiss molasse basin from the available seismic refraction data a detailed velocity depth model of the crust and uppermost mantle was derived a clear phase refracted in the basement with a velocity of 5 9 km s is observed for all shots this phase is followed by a reflection from the upper boundary of a low velocity zone this zone is very accentuated under the northern and central black forest and is characterized by a velocity decrease from 6 2 to 5 4 km s between depths of about 8 and 14 km towards the south the velocity inversion gradually loses its intensity under the center of the southern black forest velocities of about 6 km s prevail throughout the upper crust the lower crust which starts at the lower boundary of the low velocity zone shows a very complicated response in the record sections due to long reverberations between travel times of 1 5 3 5 s reduced by 6 0 km s at an epicentral distance of approximately 30 70 km a classical phase correlation is not possible based on a combined interpretation of near angle and wide angle reflection data the lower crust is characterized by a stack of thin layers with alternating high and low velocities the average velocity of the laminated zone is 6 7 km s the reflection from the moho at a depth of 25 26 km is the most prominent phase at epicentral distances greater than 60 km

the seismotectonic character of the september 3 1978 swabian jura earthquake series abstract the year 1978 should be regarded as a period of relatively high seismic activity in the western swabian jura of southwestern germany the main shock on september 3 1978 with a surface wave magnitude ml 5 1 was recorded world wide and felt within a radius of 330 km prochaskova et al 1979 from over 300 shocks recorded in 1978 24 have been chosen for closer study these have a local magnitude of 3 0 or more and include earthquakes before and after the main shock the results of the study are summarized below 1 1 21 of the 24 earthquakes studied indicate left lateral horizontal strike slip 2 2 from the epicentral locations and the fault plane solutions two dominant fault plane strike directions are present these are n7 e and n22 e 3 3 a the average orientation of the tectonic stress field as determined from the 24 fault plane solutions is azimuth of major stress axis n146 e azimuth of minor stress axis n57 e b based on theoretical considerations in situ measurements and the results of the 24 fault plane solutions the angle of the maximum stress axis is n157 2 e 4 4 the hohenzollern graben does not influence the orientation of the tectonic stress field at depths greater than a few hundred metres the apparent influence on the direction of maximum stress is related to the definition of this direction and to the strike of the disturbance zone below the graben structure

a three dimensional crustal model of southwest germany derived from seismic refraction data abstract from densely covered seismic refraction data obtained in 1978 urach experiment and 1984 schwarzer zollern wald experiment and from seismic reflection data and results from previous refraction investigations a three dimensional crustal model of southwest germany was derived travel time and amplitude information of seismic refraction data were interpreted with two dimensional forward modeling ray tracing to calculate two crustal cross sections in southwest germany these results fill a gap in the existing data and enabled the construction of a detailed three dimensional crustal model while seismically the upper crust is laterally homogeneous 5 9 6 0 km s throughout the area the middle and lower crust show pronounced lateral variations in thickness velocity and reflectivity the moho is a flat surface at a relatively shallow depth 25 26 km we classify the middle and lower crust of southwest germany into two characteristic crustal types type i consists of a mid crustal low velocity zone 5 4 5 8 km s overlying a thick 10 km high velocity 6 6 6 8 km s lower crust type ii has no prominent mid crustal low velocity zone and a thin

shear wave velocity and poisson s ratio structure of the upper lithosphere in southwest germany knowledge of shear wave velocity structure when used with compressional wave velocity can help constrain interpretations of composition from seismic refraction results we present shear velocity vs models from high quality s wave data from southwest germany which combine with existing p wave velocity vp models to give poisson s ratio in the crust and uppermost mantle in general poisson s ratio is 0 25 in the uppermost crust 0 22 0 23 in the mid crust and varies laterally from 0 24 0 30 in the lower crust the average poisson s ratio for the whole crust is everywhere about 0 25 the laminated signature of the lower crust prominent on reflection and p wave refraction data is absent on the s wave refraction data suggesting strong vertical variations of poisson s ratio within the lower crust no shear wave refractions from the upper mantle are present even where strong p wave refractions are observed possibly indicating an increase of poisson s ratio with depth in the upper mantle we interpret these results to indicate a high quartz content or fluid phases at low pore pressure in the mid crust a high feldspar content in the lower crust and an increase in depletion of basaltic components with depth in the upper mantle

the determination of late quaternary paleoenvironments at equus cave south africa using stable isotopes and amino acid racemization in ostrich eggshell abstract the stable carbon and nitrogen isotopes from organic compounds and stable oxygen and carbon isotopes from inorganic carbonate in modern and fossil ostrich eggshell oes at equus cave south africa were used to determine relative changes in c 3 and c 4 vegetation rainfall and temperature throughout the last 17 ka amino acid racemization and three new radiocarbon dates were used to assign ages to the individual oes fragments analyzed for stable isotopes and to evaluate the stratigraphic integrity of the samples the amino acid racemization and radiocarbon data indicate that most of the oes fragments are not in correct stratigraphic context and may have been upwardly and downwardly mixed thus each fragment was placed in chronological sequence using radiocarbon calibrated amino acid racemization the stable carbon isotope data from the fossil oes do not change systematically through the last 17 ka the ostriches primarily consumed c 3 plants between 70 and 90 and smaller quantities of c 4 plants between 30 and 10 indicating that a mixture of c 3 and c 4 plants has been in the vicinity of equus cave for the last 17 ka stable nitrogen isotope data from oes indicate that at 17 ka mean annual precipitation map was at a minimum 190 50 mm yr increased steadily to modern values by 6 ka 600 150 mm yr and remained relatively unchanged until present stable oxygen isotope data coupled with nitrogen isotope data indicate that paleotemperatures were at a minimum between 14 and 17 ka and reached their maximum in the latest holocene this study demonstrates the plethora of paleoenvironmental information that can be derived from analysis of three different stable isotopes carbon nitrogen and oxygen in the same sample type oes and presents a new tool with wide applicability for reconstructing paleoenvironments in semi arid and arid regions of africa

shallow subduction zone earthquakes and their tsunamigenic potential summary we have examined the source spectra of all shallow subduction zone earthquakes from 1992 to 1996 with moment magnitude 7 0 or greater as well as some other interesting events in the period range 1 20 s by computing moment rate functions of teleseismic p waves after comparing the source spectral characteristics of tsunami earthquakes earthquakes that are followed by tsunamis greater than would be expected from their moment magnitude with regular events we identified a subclass of this group slow tsunami earthquakes this subclass consists of the 1992 nicaragua the 1994 java and the february 1996 peru earthquakes we found that these events have an anomalously low energy release in the 1 20 s frequency band with respect to their moment magnitude although their spectral drop ov is comparable to those of the other earthquakes from an investigation of the centroid and body wave locations it appears that most earthquakes in this study conformed to a simple model in which the earthquake nucleates in a zone of compacted and dehydrated sediments and ruptures up dip until the stable sliding friction regime of unconsolidated sediments stops the propagation sedimentstarved trenches e g near jalisco can produce very shallow slip because the fault material supports unstable sliding the slow tsunami earthquakes also ruptured up dip however their centroid is located unusually close to the trench axis the subduction zones in which these events occurred all have a small accretionary prism and a thin layer of subducting sediment ocean surveys show that in these regions the ocean floor close to the trench is highly faulted we suggest that the horst and graben structure of a rough subducting oceanic plate will cause contact zones with the overriding plate making shallow earthquake nucleation and up dip propagation to the ocean floor possible the rupture partly propagates in sediments making the earthquake source process slow two factors have to be considered in the high tsunami generating potential of these events first the slip propagates to shallow depths in low rigidity material causing great deformation and displacement of a large volume of water second the measured seismic moment may not represent the true earthquake displacement because the elastic constants of the source region are not taken into account in the standard cmt determination

230th u burial dating of ostrich eggshell abstract obtaining precise and accurate dates for late quaternary terrestrial sequences containing middle stone age or middle paleolithic archaeological materials ca 30 300 ka can be challenging many such sequences lie beyond the limit of radiocarbon dating 50 ka and lack volcanic ashes suitable for 40ar 39ar dating we report a dating approach with about ten times the range of radiocarbon dating 500 ka based on a novel protocol for 230th u dating of ostrich eggshell a common component of african near eastern and asian archaeological sequences uranium in ostrich eggshell typically at levels of tens to hundreds of ppb is acquired after burial however accurate burial ages can be determined from measured 230th u ages when corrected for uranium uptake via diffusion using ostrich eggshells from a pleistocene holocene east african site we have 1 characterized the spatial distribution of uranium and common thorium 232th concentrations in ostrich eggshell by laser ablation icp ms 2 determined apparent 230th u ages on outer and inner layers of eggshells by solution icp ms analyses of selectively abraded eggshells and 3 calculated 230th u burial ages using a simple model for diffusive uptake of uranium we assess our method by comparing the 230th u burial ages median uncertainty 2 3 1 sd with radiocarbon dates on carbonate from the same eggshells we find good agreement in seven out of nine eggshells confirming the accuracy of their 230th u model ages eggshells that fail to yield reliable 230th u ages may be recognized by anomalous patterns of apparent 230th u ages providing a reliability criterion innate to the 230th u data ostrich eggshells are resistant to diagenesis simplifying 230th u dating compared to bones and teeth eggshells of ostrich emu rhea and other living and extinct ratites found on six continents share similar structure and composition suggesting our new approach to 230th u dating of eggshell may be applicable in diverse late quaternary terrestrial settings

numerical dating algorithms of amino acid racemization ratios from continental ostracodes application to the guadix baza basin southern spain abstract age calculation algorithms for the d l ratios of five amino acids isoleucine leucine aspartic acid phenylalanine and glutamic acid analysed in continental ostracodes were determined for southern and central iberian peninsula and allow the numerical dating of deposits in the mediterranean area since lower pleistocene time to present in order to obtain more accurate results for young samples other algorithms were calculated for aspartic acid phenylalanine and glutamic acid using these algorithms together with paleomagnetism the chronostratigraphy of the composite stratotype section of the east domain of the guadix baza basin that covers most of the pleistocene from the plio pleistocene boundary to 279 77 ka has been obtained ostracodes represent a formidable tool for amino acid racemization dating purposes in view of their abundance valves mineralogy and the high degree of preservation of amino acids within their caparaces even in old early pleistocene samples these results suggest that the range of the amino acid racemization dating method in the iberian peninsula is older than 1 1 ma

the deep crust of the southern rhine graben reflectivity and seismicity as images of dynamic processes abstract the rhine graben part of the european cenozoic rift system deserves special attention because of its location in the foreland of the alpine orogen the phanerozoic evolution of the lithosphere in this region is defined by a set of major geodynamic events ranging from the variscan orogeny late orogenic crustal re equilibration to the interference of rifting and alpine orogeny in tertiary times the rhine graben is one of the most detailedly studied continental grabens prospecting for hydrocarbons in its sedimentary fill and intensive pre site studies for the continental deep drilling program ktb on its eastern crystalline flank black forest provided a comprehensive set of geoscience data seismic investigations ranging from a deep seismic network of near vertical reflection to concurrent wide angle refraction experiments were accompanied by seismological and geological surveys therefore a direct observational comparison between the two depth definitions of crustal subdivisions elastic vs strength rheological was possible in large parts of western europe deep seismic sounding dss investigation distinguishes between a crystalline upper crust of comparatively low p wave velocities 5 9 6 0 km s with little and discrete reflectivity and a strongly reflective lower crust with higher p wave velocities about 6 4 6 8 km s both are separated by the conrad discontinuity in contrast strength and rheological considerations define a brittle upper crust and a ductile lower crust the boundary between these two realms is usually referred to as the brittle ductile transition zone which in seismically active regions is imaged by the deepest crustal hypocentres the present brittle ductile transition in the rhine graben region as defined by the deepest hypocentres does not necessarily coincide with the structural separation in an upper and lower crust as seen in deep seismic studies this suggests that the laminated lower crust developed during the crustal re equilibration phase at the end of the variscan orogeny the second part of this paper concentrates on evidence of recent tectonic activities related to rifting processes impacting on the variscan lower crust a remarkable concentration of deep crustal earthquakes reaching to the top of an asymmetrical thinned lower crust is observed at or near the eastern border fault of the southern rhine graben and is possibly induced by the young rifting process we suggest that this asymmetry could be a consequence of the uppermost mantle detaching from the upper crust in collision with the alpine orogen this allows us to propose the distinction between the influence of compression extension continental subduction and intra crustal detachment during graben formation the dynamic interference of rifting and foreland compression shown by structural and seismological observations leads to the notion of small scale collisional escape tectonics associated with an intra continental transform fault at the southern end of the rhine graben the rhine sao ne transform zone

real time monitoring of moment magnitude by waveform inversion 1 an instantaneous measure of the moment magnitude mw of an ongoing earthquake is estimated from the moment rate function mrf determined in real time from available seismic data using waveform inversion integration of the mrf gives the moment function from which an instantaneousmw is derived by repeating the inversion procedure at regular intervals while seismic data are coming in we can monitor the evolution of seismic moment and mw with time the final size and duration of a strong earthquake can be obtained within 12 to 15 minutes after the origin time we show examples of mw monitoring for three large earthquakes at regional distances the estimated mw is only weakly sensitive to changes in the assumed source parameters depending on the availability of seismic stations close to the epicenter a rapid estimation of the mw as a prerequisite for the assessment of earthquake damage potential appears to be feasible

an aminostratigraphy for the british quaternary based on bithynia opercula aminostratigraphies of quaternary non marine deposits in europe have been previously based on the racemization of a single amino acid in aragonitic shells from land and freshwater molluscs the value of analysing multiple amino acids from the opercula of the freshwater gastropod bithynia which are composed of calcite has been demonstrated the protocol used for the isolation of intra crystalline proteins from shells has been applied to these calcitic opercula which have been shown to more closely approximate a closed system for indigenous protein residues original amino acids are even preserved in bithyniid opercula from the eocene showing persistence of indigenous organics for over 30 million years geochronological data from opercula are superior to those from shells in two respects first in showing less natural variability and second in the far better preservation of the intra crystalline proteins possibly resulting from the greater stability of calcite these features allow greater temporal resolution and an extension of the dating range beyond the early middle pleistocene here we provide full details of the analyses for 480 samples from 100 horizons 75 sites ranging from late pliocene to modern these show that the dating technique is applicable to the entire quaternary data are provided from all the stratotypes from british stages to have yielded opercula which are shown to be clearly separable using this revised method further checks on the data are provided by reference to other type sites for different stages including some not formally defined additional tests are provided by sites with independent geochronology or which can be associated with a terrace stratigraphy or biostratigraphy this new aminostratigraphy for the non marine quaternary deposits of southern britain provides a framework for understanding the regional geological and archaeological record comparison with reference to sites yielding independent geochronology in combination with other lines of evidence allows tentative correlation with the marine oxygen isotope record

thermal ionization mass spectrometry u series dating of a hominid site near nanjing china mass spectrometric u series dating of speleothems from tangshan cave combined with ecological and paleoclimatic evidence indicates that nanjing man a typical homo erectus morphologically correlated with peking man at zhoukoudian should be at least 580 k y old or more likely lived during the glacial oxygen isotope stage 16 similar to 620 ka such an age estimate which is similar to 270 ka older than previous electron spin resonance and alpha counting u series dates has significant implications for the evolution of asian h erectus dentine and enamel samples from the coexisting fossil layer yield significantly younger apparent ages that of the enamel sample being only less than one fourth of the minimum age of nanjing man this suggests that u uptake history is far more complex than existing models can handle as a result great care must be taken in the interpretation of electron spin resonance and u series dates of fossil teeth

archaeology palaeoenvironment and chronology of the tsodilo hills white paintings rock shelter northwest kalahari desert botswana abstract excavations conducted at the white paintings rock shelter wps have uncovered 7 m of deposits ranging in age from the historic period to at least 100 000 years at the base eleven stratigraphic units are described in relation to palaeoenvironmental conditions inferred from sediments and other data these units contain seven major divisions in the cultural sequence highlighted by a lengthy record of later and middle stone age deposits a wide variety of mammals as well as other animals were found in the upper 3 m numerous fish bones wetland mammals and barbed bone points make this site especially interesting because of its desert location the highest frequencies of fish bones are found between c 80 90 130 cm upper fish deposits and between 210 280 cm below the surface lower fish deposits most of the barbed bone points were recovered in the upper fish deposits the lower fish deposits contain extinct equus capensis and a microlithic industry as well as some bone points a large blade industry is found beneath the lower fish deposits this blade industry shows continuity with the underlying middle stone age

tsunami generation by horizontal displacement of ocean bottom tsunami generation by an earthquake is generally modeled by water surface displacement identical to the vertical deformation of ocean bottom due to faulting the effect of horizontal deformation is usually neglected however when the tsunami source is on a steep slope and the horizontal displacement is large relative to the vertical displacement the effect becomes significant we show this for two recent earthquakes which generated much larger tsunamis than expected from seismic waves in the case of the 1994 june 2 java indonesia earthquake the focal mechanism was a very shallow dipping thrust and the source was near a very steep trench slope in the case of the 1994 nov 14 mindoro philippines earthquake strike slip faulting extended from ocean to land perpendicular to the coast line in both cases we found that the horizontal motion of slope had an important contribution to the tsunami generation

amino acid racemization of fossil bone abstract a study of aspartic acid racemization in different fractions of 51 fossil bones of various ages shows that the collagen rich fractions do manifest increasing d aspartic acid contents with increasing age no such correlation exists for the fractions rich in non collagenous proteins more collagen rich samples particularly from bones in older sites are needed to verify the generality of this trend

application of mwp to deep and teleseismic earthquakes the broadband moment magnitude m wp tsuboi et al 1995 allows for the effective determination of earthquake magnitude by using broadband p waveforms it was developed to determine moment magnitude of shallow earthquakes around the japanese islands for early tsunami warnings tsuboi et al 1995 demonstrated that m wp shows good agreement with the m w from harvard centroid moment tensor cmt solutions in the present study we show that m wp is also applicable to deep earthquakes and earthquakes recorded at teleseismic distances the m wp proves to be useful for quick accurate size estimates of earthquakes recorded at both regional and teleseismic distances occurring at any depth

lake eyre palaeohydrology from 60 ka to the present beach ridges and glacial maximum aridity lake eyre is presently an ephemeral playa lake in an extremely large 1 3 million km2 internal drainage basin with most of its inflow derived from monsoon watered northern australia the hydrologic state of the lake has varied in the past in response to climate change from a perennial lake up to 25 metres deep to a groundwater controlled playa marked by substantial sediment deflation this paper is concerned with the stratigraphic record of the last 60 ka of that hydrologic history particularly the character and age of a playa marginal unit formed by deflation from the playa and of stranded high beach ridges a major deflation episode between 60 and 50 ka excavated the present lake eyre basin and deposited a gypsum and clay rich aeolian phase the williams point aeolian unit at a number of sites around the lake after deflation ceased a thick secondary gypsum profile developed on the dune early in oxygen isotope stage 3 evidence for the state of lake eyre at this time is equivocal preliminary results from a substantial suite of amino acid racemization aar analyses of mollusc shell and bird eggshell samples from beach ridges at 5 and 10 m australian height datum ahd suggest that they are oxygen isotope stage 5 in age sedimentologic evidence suggests that it is unlikely that the shells are reworked from older deposits these aar results apparently conflict with early oxygen isotope stage 3 thermoluminescence tl dates from the 5 m ahd beach ridge nanson et al this volume however the age difference is not substantial the calibration of the aar is still at a preliminary stage and only one site was sampled for both techniques further stratigraphic and chronologic work is required to fully assess the apparent discrepancy between about 30 000 and 12 000 yr b p lake eyre was at least as dry as it is today at many sites around madigan gulf a lunette like playa marginal aeolian unit the shelly island unit was deposited during this period formed by material deflated from the playa floor forty ams radiocarbon dates span the period 35 000 to 10 000 yr b p from the shelly island unit 11 and from aeolian sediment close to playa level 29 indicating that the lake was dry during this period this evidence conflicts strongly with 2 tl dates from latest oxygen isotope stage 3 and oxygen isotope stage 2 from the 5 and 10 m ahd beach ridges nanson et al this volume additionally the aar results from the high beach ridges cannot be reconciled with these tl dates after 10 000 yr b p a minor lacustral phase occurred until the modern ephemeral playa regime became established at 3000 4000 yr b p

dating pleistocene archeological sites by protein diagenesis in ostrich eggshell eggshells of the african ostrich struthio camelus ubiquitous in archeological sites in africa have been shown by laboratory simulation experiments to retain their indigenous organic matrix residues during diagenesis far better than any other calcified tissue yet studied the rate of l isoleucine epimerization to d alloisoleucine follows reversible first order kinetics and has been calibrated for local temperature effects and used to estimate the age range of stratified archeological sites age estimates are consistent with radiocarbon dates from several stratified archeological sites with adequate calibration this technique can provide accurate ages to within 10 to 15 percent for strata deposited within the last 200 000 years in the tropics and the last 1 000 000 years in colder regions such as china