importance of on scale observations of first arriving rayleigh wave trains for source studies example of the chilean event of march 3 1985 observed on the geoscope and ida networks a comparative moment tensor inversion study of the chilean event of march 3 1985 is performed using very long period rayleigh wave data from the ida and geoscope networks it is shown that the perturbing effects of lateral heterogeneity on the propagation of the rayleigh waves especially in the amplitudes can be minimized if first arriving trains r1 and r2 only can be used more stable estimates of the main source parameters can then be obtained as well as an estimate of source directivity compatible with the aftershock distribution and body wave results

the pre quaternary history of fire abstract although evidence for land vegetation comes from the silurian and maybe even earlier the first record of fossil charcoal fusain is from the late devonian for this period there are only one or two isolated records not until the early carboniferous is there a record of extensive charcoal deposits mainly preserved in near shore clastic sediments which provide evidence of significant and widespread wildfires by the late carboniferous charcoal was common or abundant in a wide range of facies including tropical wetland peats wildfire played an important role in shaping the environment at this time the latest palaeozoic and early mesozoic records of charcoal are fewer whereas important deposits of late mesozoic age are found worldwide the occurrence of charcoal at the cretaceous tertiary boundary has been highlighted as evidence for a global fire following a meteorite impact but this interpretation is questionable charcoal has been widely reported from tertiary sediments and its appearance in the quaternary and recent is not solely as a result of human impact through the past 400 million years there have been major changes in atmospheric oxygen levels that affected fire intensity and frequency fire systems thus have a long history and their impact on shaping the environment is assessed

southern ocean bottom water of the australian new zealand sector the bottom water characteristics of the southeast indian ocean and southwest pacific ocean reveal northward transfer of cold water across the mid ocean ridge at the discordance zone near 120 e and at the balleny fracture zone near 155 e a principal northward flow which transfers cold continental margin waters of antarctic origin to lower latitudes within the south indian basin occurs to the east of kerguelen plateau within the south indian basin near the 0 c isotherm the s o2 and si relations display significant slope changes the more variable water below 0 c is of local origin while the water above 0 c represents larger scale regional effects

waxing and waning lyrical on hiatuses eocene quaternary indian ocean hiatuses as proxy indicators of water mass production the temporal distributions of cenozoic hiatuses in the indian ocean are reconsidered in the light of a new time framework developed by the paleoceanographic indian ocean synthesis on the basis of the temporal distribution of hiatus terminations eight 3 m y time slices were selected for plotting the paleogeographical distribution of hiatus terminations these distributions define areas of potential hiatus development which formed along flow paths of proto antarctic bottom water an analogue of modern antarctic bottom water and proto antarctic intermediate water an analogue of modern antarctic intermediate water expansion and contraction of these areas suggested changes in the volume of these water masses which modified the distibution patterns of erosive deepwater currents and corrosive bottom water consequently the spatial and bathymetric distribution of hiatus formation was altered age depth analysis of hiatuses from sites within post late eocene areas of potential hiatus development was used in conjunction with models of the behavior of unconformity boundaries within fluctuating water masses to construct waxing waning curves for proto antarctic bottom water and proto antarctic intermediate water these curves define volume changes in the production histories of these water masses which were related to the post late eocene glacial history of antarctica since the late oligocene the proto antarctic bottom water waned during intervals of increased glacial intensity whereas the proto antarctic intermediate water waxed during these intervals these relationships reversed during intervals of reduced glacial intensity including intervals where there is no evidence for antarctic glaciation this conflicts with interpretations made by other workers a comparison is made between the production histories of proto antarctric bottom water and northern component water an analogue of north atlantic deep water based on 13c for the miocene to pliocene

pedology of archaeological soils in tells of the judean foothills israel abstract tells archaeological mounds predominantly consist of poorly consolidated to unconsolidated sediments and soils that are highly anthropogenic this study examines pedogenic processes related to carbonate mobilization in tells in comparison with their peripheral soils reference soil profiles the key objective of this study is to test the hypothesis that tell deposits evolve through concurrent processes of sedimentation and pedogenesis synlithogenic pedogenesis and further explain it case studies are presented from three tells in semi arid and mediterranean climatic zones of the levant the methods applied included field survey analyses of particle size distribution ph caco3 and organic carbon content and soil micromorphology soils of the tells contain miscellaneous cultural materials that derive mainly from degraded mud bricks pottery and burnt wood chemical data show basic ph values high caco3 content and minor amounts of organic carbon field observations and lab analyses both indicate high similarity amongst the tells and their reference soil profiles buried tell soils show same characteristics as near surface soils however the reference soil profiles show incipient horizonation slightly darker colours and more developed structure micromorphology of both the tells and the reference profiles show cohesively welded peds in a vughy microstructure groundmass with an open porphyric c f related distribution and discontinuous carbonate recrystallization relative rates of soil formation in the tells can be estimated when archaeological records are established contrary to the tells the reference soil profiles show lower porosity and only minor remnants related to earth construction materials we classify the soils of the studied tells as archaeological calcareous anthraltic xerorthents the correlative wrb classification would be calcic urbic technosols archaic the anthropogenic materials are as calcareous as the natural soils but due to human action carbonates in the tells are distributed differently based on these observations ancient human actions and the dry climate have led to very little mobilization and accumulation of carbonates the information provided in this study adds to the pedological understanding of archaeological environments specifically it can be useful for the study of site formation processes of tells

focal mechanisms of moderate size earthquakes from the analysis of single station three component surface wave records abstract the method proposed a few years ago by ekstrom et al 1986 to retrieve the focal mechanism parameters from a set of love and rayleigh waves recorded on a single station is extended to regional intermediate size earthquakes this method is based on the inversion of the source phase and amplitude spectra in terms of the seismic moment tensor components for large teleseismic events the success of the method relies mainly on the possibility to correct the observed surface wave spectra for propagation effects by using globally averaged phase velocities for moderate size earthquakes m s 4 5 to 5 5 the periods of interest are shorter and it is no longer possible to apply this technique due to large regional variations of the propagation parameters in the method we propose here a dispersion analysis of the regional love and rayleigh wave data is first performed in the period range 30 to 100 sec the phase velocities obtained by integration of the apparent group velocities observed on the seismograms themselves and a standard q value are used to correct for the propagation effects the validity of the method is tested on synthetic seismograms and an application to long period records observed at different stations are then presented earthquakes in the pacific ocean the atlantic ocean and the mediterranean regions are used for this purpose the feasibility of the method is also tested with an historical record made on wiechert and galitzin seismometers for an earthquake that occurred in peru in 1946 finally an example of rapid computation of fault plane solution made after the armenia earthquake of 7 december 1988 is presented

dispersion and attenuation of mantle waves through waveform inversion summary we propose a new approach to the determination of elastic and anelastic parameters of the earth s structure from seismic data instead of measuring such functionals of the medium response as the phase delay or spectral ratios we perturb parameters of the model to satisfy the observed waveforms the advantage of our waveform inversion technique wit is that it uses the properties of the earth as a smoothing filter also because the earth s structure is the common denominator the method allows simultaneous interpretation of different functionals of this structure for example the waveforms of rayleigh and love waves for the same source receiver pair following extensive testing of the method on synthetic and actual data we subject results of our analysis of 37 recordings for various sources and stations to pure path decomposition the period range of analysis extends from 160 to 630s we distinguish four types of regions stable continents areas tectonically active within the last 400myr ocean floors younger than 38 myr and old ocean floors older than 38 myr the results indicate significantly different responses of the oceanic and continental areas at long periods stable continental and tectonic regions have nearly the same dispersion for periods greater than 300 35os and then diverge rapidly with stable continents showing higher velocities the young and old oceans on the other hand become distinct at periods as long as 500 s the old oceans are faster in terms of shear velocity models the data are consistent with a difference of about 4 per cent between the young and old oceans in a depth range from 400 to 670 km while the continental regions are similar and close to the global average at shallower depths our structures are conceptually similar to those inferred from previous pure path analyses and short period surface wave studies while we cannot yet establish statistically significant differences in q for the four regions such differences are obtained if one distinguishes only between continents and oceans the q for the latter is 10 20 per cent lower in the period range of the analysis

long period seismic source inversions using global tomographic models summary we investigate the effect of laterally varying earth structure on centroid moment tensor inversions using fundamental mode mantle waves theoretical seismograms are calculated using a full formulation of surface wave ray theory calculations are made using a variety of global tomographic earth models results are compared with those obtained using the so called great circle approximation which assumes that phase corrections are given in terms of mean phase slowness along the great circle and which neglects amplitude effects of heterogeneity synthetic tests suggest that even source parameters which fit the data very well may have large errors due to incomplete knowledge of lateral heterogeneity the method is applied to 31 shallow large earthquakes for a given earthquake the focal mechanisms calculated using different earth models and different forward modelling techniques can significantly vary we provide a range of selected solutions based on the fit to the data rather than one single solution difficulties in constraining the dip slip components of the seismic moment tensor often produce overestimates of seismic moment leading to near vertical dip slip mechanisms this happens more commonly for earth models not fitting the data well confirming that more accurate modelling of lateral heterogeneity can help to constrain the dip slip components of the seismic moment tensor

late cretaceous sediment sample from the amirante passage western indian ocean erosion associated with deep thermohaline flow through the amirante passage western indian ocean has caused upper cretaceous sediments to become exposed at the sea floor the age of a core of these sediments is the strongest direct evidence to date with which to support interpretations of the sea floor spreading history of the area based on geophysical data

depth determination for shallow teleseismic earthquakes methods and results the depths of moderate sized shallow earthquakes can be routinely determined to an accuracy of several kilometers using teleseismic data alone making it possible to determine the vertical positions of earthquakes within the lithosphere this capability provides a valuable tool for plate tectonic studies since earthquake depths can be used to constrain lithospheric thermal and mechanical structure at plate boundaries and in intraplate regions two basic techniques are used for depth analyses surface wave spectra can be used to determine focal depths as mode excitation reflects the behavior of the eigenfunctions with depth the primary limitation on such studies stems from lateral heterogeneity of velocity structure the waveforms of body waves are also diagnostic of focal depth which controls the time separation between the direct arrival and near source surface reflections these studies can be limited by a partial trade off between depth and source time function duration the reliability of the body wave modeling approach now in general use is shown by excellent agreement between depths determined by different investigators using different algorithms the depth determination is robust to typical uncertainties in focal mechanism and near source structure the trade off with source time function duration generally does not produce major difficulties for small events ms 6 5 for larger events the trade off can be resolved using a approach in which for a given depth the time function yielding the best fit to a suite of seismograms is found by deconvolution deconvolution at a series of depths yields a misfit function whose minimum indicates the focal depth tests with synthetic data show that the deconvolution process yields reliable depth estimates even given uncertainties in focal mechanism and near source structure it successfully handles multiple sources moderate sized finite sources and horizontally propagating ruptures good results are obtained for vertically propagating ruptures until the fault area becomes so large that waveforms differ significantly from the point source approximation a number of important tectonic results have emerged from studies using these depth determination methods the maximum depth of oceanic intraplate seismicity increases with lithospheric age and is approximately bounded by the 750 c isotherm this depth roughly equals the flexural thickness of the lithosphere but is much less than the depth to the low velocity zone indicated by surface wave dispersion the maximum depth of continental intraplate seismicity is also temperature limited but by a lower temperature these observations are consistent with the rapid weakening of the appropriate rocks with depth predicted by standard temperature dependent rheologies the maximum depth of oceanic transform seismicity corresponds to an isotherm of about 400 c this temperature is lower than would be predicted from the intraplate results and may indicate that transforms are either hotter or weaker than expected the depths of ridge crest earthquakes large enough for teleseismic analysis are extremely shallow 0 8 km the depth distribution of seismicity in continental normal faulting regions provides constraints on the nature of the extension process at subduction zones precise depth determinations can resolve the upper and lower flexural regions in the bending downgoing plate precisely locate the plate interface and map the vertical extent and position of faulting in large earthquakes

depth resolution of earthquakes in central asia by moment tensor inversion of long period rayleigh waves effects of phase velocity variations across eurasia and their calibration the moment tensor inversion method for long period rayleigh waves is discussed from the point of view of event depth resolution in this method depth is usually determined by finding the minima in appropriate least squares residuals versus depth curves we show that depth cannot be resolved if the data are sampled only at one frequency and a choice of frequencies spanning a wide range of values yields better resolution we also show that the variance reduction at the minimum depends strongly on biases in the data provided they are not simple periodic functions in azimuth from the source since such biases are introduced in particular when the propagation corrections are inaccurate this provides a means by which to study regional trends of phase velocities this method is then applied to obtain an estimate of lateral heterogeneity in central asia starting with a reference point in the pamir mountains and a set of accurately known phase velocities on paths to eurasian wwssn stations we study the rayleigh waves at these stations in the period range 30 to 90 s for eight events located in or near the tibet plateau at stances from the reference point heterogeneity in phase velocity is thus found to be about 1000 to 1500 km in this period range constraining the source parameters of the most distant events by body wave modeling we determine new phase velocities on paths to wwssn stations from the center of the tibet plateau the variation of phase velocity with source location reaches 1 to 2 and the low velocity within tibet clearly has a dominant effect we then discuss the regionalization of phase velocities as a possible way to determine a calibration curve for a given source to receiver path we find that although the regionalized phase velocities in eurasia are stable to first order they do not seem accurate enough to be used for moment tensor inversions with arbitrary source locations this may be due to non ray theoretical effects causing the breakdown of phase velocity additivity when higher order accuracy is needed on the other hand reference phase velocities on source receiver paths can be obtained reasonably fast for events large enough so that body wave modeling is possible to constrain depth and source mechanism we demonstrate that these phase velocity curves are accurate enough for the calibration of propagation effects for another event located as much as 400 to 500 km away this provides an encouraging approach to study both structure and source mechanisms of smaller events within a highly heterogeneous continental region the only constraint is to find several events with the right magnitude of both long period body waves and surface waves

microstratigraphic and multi analytical evidence for advanced neanderthal pyrotechnology at abric romani capellades spain abstract the complexity of social behaviour by neanderthal communities is consolidated by illustrating the sophistication of fire linked activities in their home based contexts this was achieved by relating the microfacies analysis of cultural deposits to combustion structures at the abric romani capellades spain the geometry and nature of cultural microfacies from a selection of hearths and their surrounding empty areas were characterized in thin sections the related bulk fraction from the distinctive individual microstrata was extracted water sieved and examined under the binocular microscope the selective micro sampling was performed from the collection of undisturbed blocks in combustion structures of layer j 1995 excavation the procedure was applied to combustion structures from the lower layer o 2009 excavation the integrated micromorphological observation and binocular sorting allowed identification of a similar assemblage of components that are closely linked to distinctive anthropic microfacies individual grains were characterized by esem edax x ray diffraction and raman spectrometry x ray fluorescence analysis was performed on the host matrix the specific association of remarkable components cultural microfacies is identical for the combustion structures of layers o and j the four groups components identified comprise carbonaceous polymorphs allochthonous mineral clasts organo phosphatic compounds and native metals the phase association of organic and mineral phases allowed recognition of a common natural precursor rich in hydrocarbon species and metallic compounds that were probably extracted from a miocene source microscale analysis in thin sections linked the combustion microfacies to the transformation contexts of the metal rich carbonaceous precursors heat resistant polymers and graphitic components associated with wood ash are suggested to trace pyrolitic residues from flaming combustion the intimate mixing of the metal rich carbonaceous polymorphs to finely crushed heated bones allowed identification of pyrogenic transformations of the fossil fuel with fresh biomass analysis at microscale in thin sections linked the processed by products to finely prepared and meticulously consolidated surfaces showing distinctive colours yellow brown blue green red white and black the repeated surface preparation and their exceptional preservation at microscales illustrate the great concern of neanderthal occupants for maintaining the long term memory of their carefully designed home space the recognition of advanced pyrotechnology by using fossil fuels for lighting firing spatial design colouring in the combustion structures of abric romani incites speculation on the exceptional social status of this home based camp site further development of the microfacies multi analytical analysis should more deeply penetrate the social sophistication of neanderthal communities

a very broad band inversion method for the recovery of earthquake source parameters abstract waveform studies of the earthquake source have traditionally been performed in narrow bands of the seismic spectrum waveform matching of p and sh waves emphasizes frequencies near and above the corner frequency normal mode and surface wave analyses on the other hand are performed on data which contain information only below the corner frequency a new method is presented which formally includes the result of a long period centroid moment tensor analysis in an inversion of broad band body wave phases a parametrized source model is used which allows for the recovery of a detailed source time function as well as the direction and magnitude of rupture propagation the technical details and the performance of the method are demonstrated in an analysis of the october 28 1983 borah peak idaho earthquake in particular it is shown how the combination of the long period and broad band data sets in the inversion improves the resolution of both the focal mechanism and the scalar moment the very broad band method is applied in an analysis of the september 19 1985 michoacan m w 8 0 earthquake two concentrations of moment release are identified in the source time function separated by 25 30 s in time the spatial distribution of moment is well explained both by a model of unilateral rupture towards the east with a propagation velocity of 2 4 km s 1 and by two point sources separated by 95 km it is shown that the p wave data are largely insensitive to the scalar moment and that source time functions obtained without consideration of the total moment release exaggerate the heterogeneity of slip on the fault plane source time functions which do contain the total moment show that a large fraction of the moment was released smoothly over the whole duration 80 s of the event the results suggest that the fault plane was characterized by two regions of high stress drop but that a large portion of slip occurred on surrounding weak portions of the plane

miocene changes in bottom current regime recorded in continental rise sediments on the pacific margin of the antarctic peninsula a fossil mounded sedimentary body mb has been identified in the miocene sedimentary record on the central continental rise west of adelaide island antarctic peninsula using multichannel seismic reflection profiles the mb has an elongated ne trend away from a group of seamounts and it developed between two troughs we interpret it as a patch drift plastered against the ne lee side of an obstacle the mb s depositional patterns provide the first clear evidence of early miocene bottom current activity on the central rise and they suggest that flow was towards the ne probably as part of the antarctic circumpolar current this segment of the rise is however presently affected by a sw flowing branch of lower circumpolar deep water the change in bottom water flow took place during the middle or late miocene and we suggest that it is probably indicative of more widespread palaeoceanographic changes during this period

diagenesis in prehistoric caves the use of minerals that form in situ to assess the completeness of the archaeological record an interpretation of the archaeological record in particular that of a prehistoric cave site is complicated by the diversity of depositional and post depositional processes that affect the material deposited here we propose to use the authigenic minerals that form in situ within the cave sediments to reconstruct the ancient chemical environments in the sediments this can be done by experimentally determining the conditions under which each of the authigenic minerals are stable although this information is not available to date for minerals formed in a prehistoric cave we present calculated stability field data for the relevant minerals the results clearly demonstrate the feasibility of this approach this information particularly if based on measurements of real authigenic cave minerals will facilitate an assessment of the completeness of the cave archaeological record this is particularly important for determining whether or not the distributions of archaeologically important materials such as bones teeth plant phytoliths charcoal and ash reflect their original burial distributions or were altered as a result of secondary diagenetic processes

earth wind and fire ethnoarchaeological signals of hadza fires we present the preliminary results of an interdisciplinary ethno geoarchaeological project aimed at characterizing sedimentary aspects of recent combustion structures through soil micromorphology to obtain empirical parameters with which to interpret archaeological features micromorphological analyses of five different types of fires made and abandoned by the hadza of tanzania were performed and compared with ethnographic descriptions their anthropogenic nature burning intensity and type of fuel used were identified based on the composition and optical features of the microscopic components of the combustion structure the data provided elements to assess the preservation potential of open air fires and our ability to interpret their function the life history of two of the fires was reconstructed a sleeping fire showed evidence of a pre existing trampled surface and a communal cooking fire showed evidence of the scooping out of ashes for maintenance these findings substantiate the important contribution of ethnoarchaeological research conducted jointly with soil micromorphology in discovering cues of human behavior preserved in the sedimentary record

high resolution global phase velocity distributions we present global phase velocity distributions for fundamental mode love and rayleigh waves in the period range 40 to 150 seconds the models expressed in terms of spherical harmonic expansions up to degree and order 40 have beed derived from 28 479 love wave and 33 662 rayleigh wave measurements the measurements were made using an automatic procedure based on non linear waveform inversion we show that the results are characterized by lateral resolving radii between 500 and 850 km a significant reduction from previous work the improved global resolution is largely due to the inclusion of many more major arc measurements the power spectra of the models are much whiter than has previously been found the results show great similarity to the phase velocity distributions derived from the recent a priori model 3 smac in which the primary relevant features are the crustal thickness and crustal velocity distributions the cooling oceanic lithosphere and the thick 300km lithosphere of the continental cratons the results thus confirm these features differences for example in the strengths of the crust ridge and craton signatures should lead to refinement in the thermal and constitutive parameters upon which the a priori model depends

permineralization process promotes preservation of holocene macrofossil charcoal in soils the use of macrofossil soil charcoal as a palaeoecological tool to reconstruct past vegetation climate or fire history has gained much interest in recent years yet little is known about taphonomy of charcoal in soils here we assessed the putative loss of palaeoecological information due to charcoal fragmentation after burial we found no significant loss of charcoal mass with time instead we found a significant positive relationship between the mass of charcoal particles and their age permineralization of charcoal particles older than ca 5200 a explained the increased charcoal mass with time in mineral soils the permineralization process increased the density of charcoal particles resulting in a twofold particles mass increase and thus offers a protection against subsequent degradation our results suggest high stability of palaeoecological information from charcoal macrofossils buried in mineral soils at least over the holocene timescale copyright 2011 john wiley sons ltd

preliminary determination of focal mechanisms from the inversion of spectral amplitudes of mantle waves abstract we present a method for the preliminary determination of focal mechanisms pdfm based on the inversion of deviatoric moment tensor components from depleted datasets of mantle wave spectral amplitudes the latter are found to be largely insensitive to errors in epicentral estimates which can hamper the inversion of the full complex spectrum under real time operational conditions robust solutions can be obtained from rayleigh wave spectra at as few as three stations and from a combination of rayleigh and love waves at only two stations provided they sample 60 in azimuth the systematic application of this method to a dataset of 43 large earthquakes during 1996 1999 yielded mechanisms rotated an average of only 17 from the published harvard cmt a figure comparing favorably with the case of other catalogues such as the usgs moment tensor solutions

the palimpsest problem hearth pattern analysis and middle paleolithic site structure abstract a principal behavioral issue in paleoanthropology centers on the degree to which the behaviors of neanderthals and modern humans may have differed efforts to address this problem have employed the analysis of living floors and site structure in which researchers have traditionally emphasized a dichotomy between the site structures thought to distinguish modern human and neanderthal occupations this thinking links complex site structures characterized by several discrete activity areas to modern humans in contrast to the simple structure of neanderthals as seen in single hearths associated with overlapping generalized activities correlations between prehistoric behaviors and site structures however may be masked distorted and even destroyed by a variety of natural and cultural agencies natural post depositional processes may be associated with bioturbation cryo turbation and the degradation of sediments through wind and water erosion both post and synch deposition disturbance of artifact distributions and features by human activities may involve cleaning scuffage and other site alterations perhaps the most vexing of problems associated with post depositional distortion is from subsequent overlapping occupations in which a smearing or blurring of artifact distributions occurs i e the palimpsest problem using the results of a multi year research program of stratified living floors at the late levantine mousterian rockshelter site of tor faraj southern jordan an introduction to a partial solution of addressing the palimpsest problem through hearth pattern and ring and sector analyses is described here

the 1984 southern yellow sea earthquake of eastern china source properties and seismotectonic implications for a stable continental area on 21 may 1984 a strong shock ms 6 3 mb 5 7 occurred in the southern yellow sea which shook the densely populated coastal area of eastern china about 1 min before the main shock a foreshock of mb 5 4 occurred because of interference from the foreshock no reliable p wave first motions or focal mechanisms have been obtained for the main shock from local seismic data in this paper long period teleseismic data have been used to investigate the source mechanism fault plane solutions determined from first motions as well as p and sh waveforms show a predominant strike slip motion with a small dip slip component on a steeply dipping plane the tectonic environment of this event supports the observation that margins of former rifts tend to be sites of midplate seismic source regions the yellow sea developed in a cratonic environment due to early cenozoic rifting the major graben faults strike nne ssw to ne sw and are intersected by second order faults trending wnw ese aftershock distribution suggests that the fault which generated the main shock probably strikes wnw ese the mechanism determined in this paper strikes 120 dips 88 and slips 28 this solution suggests that the earthquake ruptured along a secondary fault near the intersection of a more major nne ssw trending fault the epicentral area is subject to to an ene wsw compression and a nnw sse extension the seismic moment and focal depth are determined to be 1 09 1025 dyne cm and 12 4 km respectively relative hypocentral locations indicate that the focal depth of the foreshock is similar to that of the main shock and the hypocenter of the foreshock is located very close to the wnw ese striking nodal plane of the main shock mechanism and is about 20 km away from the main shock hypocenter source properties of the southern yellow sea earthquake have been compared with those of three major earthquakes of north china the stress drop of the yellow sea earthquake is determined to be about 42 bars this value is much lower than the stress drops computed for the 1966 hsingtai and the 1975 haicheng earthquakes of north china the southern yellow sea is characterized by short recurrence intervals while the hsingtai and haicheng areas have very long recurrence intervals the short recurrence intervals and low stress drop may reflect a lower material strength at the source region in the yellow sea

fuel origin and firing product preservation in archaeological occupation contexts abstract we intend here to examine the range of factors involved in the preservation at short to long term of firing byproducts with respect to the nature of combustion processes and the fuel origin our objective is to refresh the cultural and palaeoenvironmental relevance of combustion deposits the study is based on the comparison of two recent situations of natural fires and a selection of well preserved firing records from rockshelters and caves in diverse geographical and cultural contexts the recent analogues comprise a two year investigation of the 2012 july large forest fire at alt emporda northern cataluna spain and a study of the 2014 lightning struck pine tree allanche cantal france in situ characterization at micro to nanoscale of firing products has been performed using the sem eds in backscatter mode on individual grains and composite aggregates which were extracted by gentle water sieving from combustion microstrata and firing products meticulously sampled in the field the survey of the alt emporda firing record confirms the rapid loss of intact ashes and heating scars leaving after two years a regenerated soil without any obvious evidence of this fire except for scattered charcoal the study of allanche lightning struck pine tree shows that lightning produces a suite of robust components diagnostic of flash heating and plasma assisted combustion polymer filaments vitreous char metal coatings and singular minerals their durability expresses the refractory and hydrophobic properties of materials formed by transient heating and plasma processes the identification of similar robust components in all the firing products of the archaeological contexts tested here shows that plasma assisted combustion and flash heating exert a major role on the durability of firing records the archaeological combustion contexts are separated into two types of intact firing records 1 the ones with abundant mineralised charcoal vitreous char and metal coatings would trace the use of fuel acquired from wood affected by a lightning strike 2 the thick white ash with polymer films refractory minerals and metal coatings would indicate wood fuel collected during periods of active aeroplasma processes in the atmosphere due to increased dust loading and intense ionization the study is suggested to offer a challenging perspective to elucidate further the role that lightning and plasma processes exerted on ancestral pyrotechnology by occasionally providing wood fuel resources of long durability low degradability and high calorific power

giant mounded drifts in the argentine continental margin origins and global implications for the history of thermohaline circulation abstract partially buried giant drifts are located in the southern most sector of the argentine continental margin generating a bathymetric jump at the base of the slope they are characterised as giant asymmetrical elongated mounded contourite drifts and are described in detail here for the first time this description is mainly based on the bathymetric and multichannel seismic reflection profiles data their origin and evolution in the argentine basin are decoded and their implications in an area crucial for geologic and palaeoceanographic reconstruction between the atlantic and antarctica are discussed the buried giant drifts are divided into two zones by a large seamount the major giant drift 50 km wide 300 km long and having a sedimentary thickness of nearly 1 km is located to the south of this seamount and oriented to the north where its summit outcrops at present seafloor here its asymmetric external shape is characterised by a steep western side and a gently dipping smooth eastern side with internal reflections prograding eastward based on its position morphology and internal characteristics it has been deduced that this giant drift was generated in the argentine basin by the southward branch of a confined large loop of the antarctic bottom deep water from the eocene oligocene boundary coevally with the drake passage opening until the middle miocene however after a major palaeoceanographic change in the mid to late miocene a new oceanographic scenario was established that fossilised these giant drifts these changes produced a new depositional style in the margin resulting in initiation of the present contourite depositional system and morphologic features over the slope extension of north atlantic deep water circulation into the southern hemisphere and deepening of antarctic bottom water circulation in the argentine basin are herein postulated as the factors that controlled said changes these giant drifts show strong seismic evidence of hydrates and free gas that are ripe for energy resources exploration thus demonstrating the economic potential of contourite deposits in deep marine environments

the black layer of middle palaeolithic combustion structures interpretation and archaeostratigraphic implications certain aspects of the formation processes of simple flat archaeological combustion structures such as those present in the middle palaeolithic record remain unexplained such kind of combustion structures are commonly affected by postdepositional agents and often their only distinct well preserved component is a thin black lens on the ground hence understanding the nature of this black lens is essential towards archaeological interpretation from an interdisciplinary microstratigraphic approach we present a case study in which for an entire experimental series of flat combustion structures the black layer represents the fire altered topsoil on which the fire was made parallel analysis of archaeological middle palaeolithic combustion structures from the site of el salt alicante spain reveal similar patterns leading to significant implications for archaeological interpretation in the light of these results special attention must be paid to the formation processes of flat middle palaeolithic combustion features as black layers and the material contained in them are not necessarily linked with combustion but with preceding activities or events in such cases black layers represent intact remnants of occupation surfaces concealing significant behavioural and palaeoenvironmental information relevant to the reconstruction of middle palaeolithic societies

mapping the upper mantle three dimensional modeling of earth structure by inversion of seismic waveforms a method is presented for the inversion of waveform data for the three dimensional distribution of seismic wave velocities the method is applied to data from the global digital networks international deployment of accelerometers global digital seismograph network the selected data set consists of some 2000 seismograms corresponding to 53 events and 870 paths the moment tensors of the earthquakes are determined through an iterative procedure which minimizes the corrupting influence of lateral heterogeneity a global model is constructed for shear wave velocity expanded up to degree and order 8 in spherical harmonics and described by a cubic polynomial in depth for the upper 670 km of the earth s mantle although no a priori information is incorporated the model predictions reproduce much of what is known about the dispersion of mantle waves for example high phase velocities for shields low velocities at ridges and a strong degree 2 pattern for rayleigh waves since the method makes use of complete waveforms overtone data are also included it is shown that the model is reproducible in that substantially the same model can be constructed from each half of the total data set considered independently the model shows that shields and ridges are major features in the depth interval 25 250 km the ridges of the southern pacific and the larger shields persist to 350 km but the southeast indian rise is underlain by a high velocity anomaly at this depth as is much of the mid atlantic ridge at 450 650 km the major features are a broad region of high velocities incorporating south america much of the south atlantic and parts of west africa a broad region of low velocities in the central and eastern pacific high velocities in the western pacific and a low velocity anomaly beneath the red sea and the gulf of aden in the absence of a crustal correction degrees 2 and 3 show a high positive correlation with the geoid paradoxically this is largely destroyed when the distribution in crustal thickness is taken into account spherical harmonic degrees 4 7 show a significant negative correlation

inversion of surface wave spectra for source parameters of large earthquakes using aspherical earth models abstract amplitude and phase spectra of rayleigh and love waves of periods of 150 to 300 s from eight large earthquakes which occurred between 1990 and 1993 are corrected for wave propagation and then inverted for the source duration rupture directivity and moment tensor of the earthquake source for various propagation anomalies predicted by models of the earth s aspherical elastic and anelastic structure the application of corrections for the focusing and take off azimuth anomaly in addition to conventional corrections for the phase anomaly improves inversions of surface waves rayleigh waves provide better constraints than love waves in the determination of source parameters the data consist of either only rayleigh waves or both love and rayleigh waves whenever the full moment tensor is involved for several earthquakes there is clear discrepancy between source parameters determined from different data sets particularly from rayleigh or love waves the moment tensor solution tends to underpredict observed amplitude spectra for data sets with large amplitude anomalies especially for love waves this study shows that 1 the 1990 sudan earthquake is anomalous for its unusually large non double couple component of the moment tensor 2 the 1990 iran earthquake has a strike slip mechanism with a subvertical nw striking nodal plane which is the fault plane inferred from surface ruptures 3 the 1991 costa rica earthquake may have a seismic moment larger than previously determined from long period surface waves 4 the 1992 nicaragua earthquake involves a predominant rupture parallel to the trench and a large centroid offset up dip to the trench axis and the latter process may be responsible for large tsunami generation 5 the 1993 hokkaido earthquake has a shallow dipping and west plunging nodal plane which is consistent with the p wave first motions but differs from the centroid moment tensor solutions

on the limits of linear moment tensor inversion of teleseismic body wave spectra the limits of linear moment tensor inversions from long period teleseismic body waves are analysed in detail using inverse methods we focus our attention on single station and few stations methods information on the feasibility of full or deviatoric moment tensor determinations prior to inversion are deduced from the system conditioning the resolution and correlation of the momenttensor components are analysed using the resolution matrix conclusions on the importance and independence of the data are drawn from the information matrix the single station case and its implications are discussed in greater detail as well as possible constraints on the inversion

evidence for the repeated use of a central hearth at middle pleistocene 300 ky ago qesem cave israel abstract a major debate in prehistory revolves around the time and place of the earliest habitual use of fire and the hominin species responsible for it here we present a newly discovered hearth at qesem cave israel that was repeatedly used and was the focus of hearth centered human activities as early as three hundred thousand years ago the hearth identified based on mineralogical and microscopic criteria contains two superimposed use cycles each composed of shorter episodes possibly the earliest superimposed hearth securely identified to date the hearth covers ca 4 m 2 in area making it a uniquely large hearth in comparison to any contemporaneous hearth identified thus far possibly indicating it has been used by a relatively large group of people in addition the hearth is located in the center of the cave and is associated with butchered animal remains and a dense flint assemblage the flint assemblage indicates spatially differentiated meat cutting and hide working activity areas the central location of the hearth within the cave and the activities associated with it may reflect an embedded perception of space organization of the qesem cave inhabitants since fire was habitually used throughout the 420 200 ky sequence of qesem cave where preservation conditions are alike throughout we suggest that this unique hearth may reflect a development in nature and most probably in the intensity of fire use in qesem cave from ca 300 ka ago onwards

early and middle miocene stable isotopes implications for deepwater circulation and climate the middle miocene 18o increase represents a fundamental change in the ocean atmosphere system which like late pleistocene climates may be related to deepwater circulation patterns there has been some debate concerning the early to early middle miocene deepwater circulation patterns specifically recent discussions have focused on the relative roles of northern component water ncw production and warm saline deep water originating in the eastern tethys our time series and time slice reconstructions indicate that ncw and tethyan outflow water two relatively warm deepwater masses were produced from 20 to 16 ma ncw was produced again from 12 5 to 10 5 ma another feature of the early and middle miocene oceans was the presence of a high 13c intermediate water mass in the southern hemisphere which apparently originated in the southern ocean miocene climates appear to be related directly to deepwater circulation changes deep waters warmed in the early miocene by 3 c 20 to 16 ma and cooled by a similar amount during the middle miocene 18o increase 14 8 to 12 6 ma corresponding to the increase 20 ma and subsequent decrease 16 ma in the production of ncw and tethyan outflow water large 0 6 relatively rapid 0 5 m y 18o increases in both benthic and planktonic foraminifera i e the mi zones of miller et al 1991a and wright and miller 1992a were superimposed in the long term deepwater temperature changes they are interpreted as reflecting continental ice growth events seven of these m y glacial interglacial cycles have been recognized in the early to middle miocene two of these glacial interglacial cycles mi3 and mi4 combined with a 2 to 3 c decrease in deepwater temperatures to produce the middle miocene 18o shift

the december 1994 seismic swarm near aoba ambae volcano vanuatu and its relationship with the volcanic processes abstract a seismic swarm which occurred in december 1994 near the aoba volcano vanuatu is investigated in detail by analyzing local and regional broad band seismic records the seismic area is situated in a poorly instrumented region although major seismic and volcanic events are possible the data collected by four permanent short period stations the nearest one being installed in the espiritu santo island located 80 km from the volcano allowed us to locate epicenters with a 2 3 km precision and to document the present local seismicity the quality of available regional broadband data allows us to determine reliable focal parameters though the magnitude of the strongest event is 4 8 data have been selected from the permanent geoscope and iris stations located in the south western pacific region and from two temporary networks one installed in new caledonia and vanuatu by i r d and the e o s t and another one installed in fiji and tonga islands by the washington university st louis usa results obtained either with local epicentral distance d km body waves or regional 500 km surface waves lead us to conclude that the swarm is associated with the volcanic edifice but is not of volcanic type according to the definitions given by minakami phys volcanol 1974 1 and schick bull volcanol 44 1981 491 the observed mechanisms evidence an important local influence of the volcano itself on the stress field and the observed near horizontal p axis argues against a strong increase of phreatic activity in addition seismic and volcanic observations are analyzed in the framework of the interpretation of earthquake swarms occurring in the vicinity of active volcanoes

mm a variable period mantle magnitude this paper lays the theoretical groundwork for a variable period mantle magnitude mm based on the measurement of the spectral amplitude x of very long period rayleigh waves we retain the concept of magnitude by restricting ourselves to single station measurements ignoring the focal mechanism and the exact depth of the shallow earthquakes considered our measurements are made at a series of periods in all cases greater than 40 s and the largest value is retained this procedure effectively avoids the well known interference effects leading to saturation of magnitude scales defined at a fixed period two corrections are used a period dependent distance correction cd and a source correction cs also period dependent compensating for the variation of the excitation of rayleigh waves with period both of these corrections are fully predictable on the basis of standard surface wave excitation and dispersion theory the result is a formula of the type mm log10 x cd cs c0 in which all coefficients including the constant c0 are justifiable on sound theoretical grounds the analysis of a data set of 256 records from the broadband seismograph at papeete tahiti the ultra long period system at pasadena and stations of the geoscope network shows that the mean error in the estimation of the seismic moment is on the order of 0 1 0 2 units of magnitude with the standard deviation at each station also on the order of 0 2 units of magnitude no significant trend with either distance period or station can be identified the method can also be transposed to the time domain under some simple assumptions which are justifiable theoretically for typical teleseismic distances across the pacific basin both versions of the method lend themselves well to automation thus by providing a real time estimate of the seismic moment of distant earthquakes mm has considerable potential for tsunami warning purposes its concept can easily be extended to love waves and also to intermediate and deep earthquakes

a 600 000 year record of antarctic bottom water activity inferred from sediment textures and structures in a sediment core from the southern brazil basin at the northern exit of the vema channel in the southern brazil basin deep currents linked with antarctic bottom water flow aabw below 4200 m have formed contouritic accumulations along the continental rise lithologic and textural investigations were carried out on a kullenberg core in order to establish a chronology of late pleistocene holocene fluctuations in aabw flow the core spanning the last 600 000 years was recovered from a field of sediment waves the deposits consist of fine grained muds carbonate contents are very low because deposition takes place near the present day carbonate compensation depth the core stratigraphic framework is based on calcareous nannofossil and excess 230th analyses two main types of facies can be identified 1 yellowish brown muds with frequent manganese enrichments forming dark laminae and 2 homogeneous gray green muds two indicators of paleocurrent activity have been considered 1 erosional sediment features that give evidence for high amplitude and short term current events and 2 grain size fluctuations percentage of panicles greater than 10 m indicating low amplitude and long term variations two periods can be defined the first one circa 600 to circa 350 kyr b p is characterized by an instability in current activity with strong flow events recorded as erosional surfaces long term fluctuations reveal the existence of several episodes of increased velocity occurring approximately every 50 kyr the second period 350 kyr b p to present is marked by globally weaker current activity and long term fluctuations of lower amplitude and longer duration maximum velocities occur preferentially during periods of climatic cooling these fluctuations might be correlated with the 100 kyr eccentricity cycle of the earth s orbit

contribution of seismic tomography in moment tensor inversions using teleseismic surface wave spectra the knowledge of lateral heterogeneities is crucial for path corrections in moment tensor inversions using surface waves after some attempts to use regionalized earth models for very long period surface wave moment tensor inversions recent tomographic earth models offer the possibility to make short period path corrections and therefore retrieve more reliable moment tensors for teleseismic earthquakes first we try to evaluate the precision required for path corrections in comparison with source effects some selected earth models are tested to evaluate how their results compare to those using multiple frequency filtering techniques some real cases illustrate the sensitivity of moment tensor solutions to the different path corrections and it appears clearly that regionalized earth models and tomographic models deduced from long period data alone greater than 150 sec cannot lead to trustworthy broadband moment tensor inversions recent tomographic models using phase velocities at much shorter periods 40 to 200 sec offer a precision comparable to that of the multiple frequency filtering technique both methods lead to acceptable source mechanisms using a small number of stations in more than two cases out of three the use of recent global tomographic models based upon shorter period surface waves might thus be a useful alternative to heavy multiple frequency filtering techniques to automate source studies especially for rapid determinations using a small number of stations

a contourite depositional system along the uruguayan continental margin sedimentary oceanographic and paleoceanographic implications abstract for the first time a multidisciplinary approach to evaluate the influence of bottom currents in the uruguayan continental margin is presented bathymetric data and multichannel 2d and 3d seismic reflection profiles were used to construct a morphosedimentary map to interpret and decode sedimentary and oceanographic processes along the uruguayan continental margin based on these results an extensive contourite depositional system on the margin is described which contains an impressive array of large erosive depositional drifts and mixed terrace features which have been generated primarily by the near bottom flows associated with water masses of antarctic and subantarctic origin from the eocene oligocene boundary up to present time the long term influence of water masses from higher southern latitudes in combination with down slope sedimentary processes have strongly controlled the overall margin morphology most of the features described here were formed during the middle late miocene epoch due to paleoceanographic shifts that include the arrival of antarctic intermediate water along the margin which in combination with deeper antarctic bottom water are fundamental in the margin evolution in combination with quaternary climatic and eustatic changes in sea level fluctuations of the brazil malvinas confluence influenced subsequently glacial and interglacial stages as recognized in sedimentary features defined here these paleoceanographic changes controlled the sedimentary stacking pattern and the locations of high amplitude reflections along the contourite terraces which could be associated with sandy deposits a more detailed understanding of the margin will improve interpretations of variations in the south atlantic subtropical gyre and further constrain general climatic and ocean circulation models

depositional patterns at drift 7 antarctic peninsula along slope versus down slope sediment transport as indicators for oceanic currents and climatic conditions abstract understanding the processes and phases of deep sea sediment drift formation is essential for a reconstruction of their evolution this leads to a better understanding of the properties of oceanographic currents active during drift formation and in turn to information on the climatic conditions a system of sediment drifts at the antarctic peninsula pacific rise has been chosen to learn more about the neogene evolution of both current systems and palaeo climate in that area drift 7 was extensively surveyed seismic and sampling and two odp leg 178 sites were drilled there using this information maps of reflectors depth and seismic unit thickness were compiled and interpreted regarding the controlling depositional processes the depositional model shows an initially major along slope sediment transport by a sw setting bottom current 25 15 ma which deflected sediment supplied from the continental shelf between 15 ma and 9 5 ma down slope transport took over as a result of the growth of the antarctic peninsula ice sheet the sw setting bottom current appears to have broken down down slope transport has decreased since 9 5 ma but a re onset of the bottom current can only be observed since 5 3 ma the analysis has further shown that the nucleus of the drift is connected to a basement ridge it is hence inferred that basement topography played a major role in the formation of this sediment drift

development of sediment drifts approaching an active plate margin under the sw pacific deep western boundary current the abyssal pacific ocean is fed by a 1000 km wide deep western boundary current dwbc that flows northward along the continental margin east of new zealand between the passive margin of chatham rise and the subduction zone of kermadec trench a distance of 1200 km the dwbc has formed a suite of sediment drifts over a depth range of 2200 5700 m airgun and 3 5 khz profiles record a variety of drift types that reflect regional variations in bathymetry sediment supply and the tectonic volcanic framework on chatham rise the dwbc has deposited a sinuous linear body along the south flank 3000 m an extensive apronlike drift on the north flank 2200 4500 m and a ridgelike drift about the rise base 4500 5200 m the flow has also deposited a body of sediment over 400 km long within a moat at the base of the nearby louisville seamount chain further downcurrent the 250 km long rekohu drift 3600 4190 m has developed northward to 39 s south of this latitude drifts comprise mainly reworked pelagic hemipelagic material and sediment transported from distant southerly sources in contrast drifts north of 39 s have received a major injection of terrigenous sediment from hikurangi channel which runs 1400 km from new zealand eastward across the hikurangi plateau to disgorge on to the abyssal floor at the plateau edge en route turbidity current overspill from the channel has moved north under the influence of the shallow dwbc to contribute to a series of small ridge and patch drifts among the numerous seamounts on the plateau at 3500 4200 m off hikurangi channel mouth a large fan has accumulated the dwbc has extended the fan into a drift running over 250 km along the base of hikurangi plateau 5150 5770 m toward kermadec trench here drift sediment becomes increasingly disrupted by mass wasting associated with the active subduction in this area the seismic stratigraphy reveals the drifts to rest mainly on a widespread erosional surface that is interpreted to mark the inception of the dwbc in the region with the late oligocene opening of the australian antarctic seaway drift construction commenced during the miocene but was punctuated in the late miocene by another period of erosion that coincided with increased bottom water production in antarctica deposition resumed in plio pleistocene times when large quantities of sediment from the rapidly rising landmass of new zealand were injected into the boundary current the modern flow continues to affect drift deposition as manifest by an active boundary channel along the foot of hikurangi plateau and widespread scour zones and sediment wave fields

neanderthal firewood management evidence from stratigraphic unit iv of abric del pastor eastern iberia abstract this paper presents anthracological data from abric del pastor alcoi spain a middle paleolithic rock shelter site analysis of 1077 wood charcoal remains from stratigraphic unit iv s u iv collected within archaeological combustion structures and from loose sediment outside of structures allowed us to characterise the local landscape as well as to approach the interaction between neanderthal groups and their local environment taxonomic identification suggests that firewood was gathered from nearby sources with predominance of juniper juniperus sp followed by thermophilous shrubby taxa additional analysis focussing on post depositional processes affecting charcoal have shown features indicative of biodegradation and mechanical action the results of this study contribute significant anthracological data towards our understanding of late pleistocene mediterranean landscapes and neanderthal forest management in this region

stability of fault plane solutions for the major n italy seismic events in 2012 abstract we propose a critical analysis of the moment tensor solutions of the major seismic events that affected northern italy in 2012 inverting full waveforms at regional distance using the non linear method named inpar we investigate period dependent resolution that affects in particular the solutions of shallow events this is mainly due to the poor resolution of mzx and mzy components of the seismic tensor when inverting signals whose wavelengths significantly exceed the source depth as a consequence instability affects both source depth and fault plane solution retrieval and spurious large compensated linear vector dipole components arise the inversion performed at cutoff periods shorter than 20 s reveals in many cases different details of the rupture process which are supported by independent geodynamical arguments thus we conclude that inversion of full waveforms at cutoff period as short as possible should be preferred

broadband modelling of regional seismograms imperial valley to pasadena summary this paper addresses broadband wave propagation along a corridor from imperial valley to pasadena california the path consists of 50 km of slow basin structure with a shallow moho followed by 250 km of relatively normal southern california structure approaching pasadena events occurring in the valley produce extended body wave codas which carry a dispersive waveform imprint along with longer period rayleigh waves many features of these seismograms at periods greater than a few seconds can be modelled by applying a finite difference technique to a 2 d structure shorter periods display complex behaviours not easily modelled by present techniques especially for shallow events events occurring in the normal structure produce broadband sh waveforms that can be modelled analytically if some extra empirically derived alignment parameters determined from calibration events are used these parameters are determined by adjusting traveltime differentials between the decomposed wavefield s ss etc for example delays in ss relative to s correspond to local corrections for sediment cover for a particular source region source complexity such as asperities and directivity become increasingly important at shorter periods as demonstrated by numerical experiments and observation

geometric effects of global lateral heterogeneity on long period surface wave propagation long period rayleigh waves from iranian earthquakes have large amplitude asymmetries between minor arc and major arc arrivals e g r 2 and r 3 at digital stations in the azimuth range n20 w to n60 e these asymmetries are as large as a factor of 2 at a period of 256 s and persist to periods greater than 300 s in some cases the entire rayleigh wave group arrival spanning periods from 100 to 300 s is either uniformly enhanced in amplitude or diminished to such a degree that the group arrival appears to be missing the amplitude anomalies are generally not accompanied by significant phase anomalies the irregular azimuthal distribution of the amplitude asymmetries and their occurrence for events with different focal mechanisms and epicentral separations of several hundred kilometers preclude an explanation of these observations by source complexity events in the mediterranean and nepal do not produce similar amplitude asymmetries at the same stations the anomalies are thus most likely due to focusing and defocusing propagation effects as a preliminary investigation of the effects of lateral heterogeneity of upper mantle velocity structure on long period surface wave amplitudes surface wave ray tracing calculations are performed using recently proposed global phase velocity distributions dramatic deviations from great circle paths are predicted for long propagation paths e g r 3 the particular spatial distribution of lateral velocity gradients around a given source location determines whether substantial amplitude asymmetries will be observed between minor arc and major arc arrivals and whether these will persist for sequential great circle orbits the 200 s period amplitude asymmetry observed at kip for the iranian source region r 2 4 r 3 is well predicted by the ray tracing results the absence of this anomaly for the other source regions is also predicted other observed anomalies are not all well predicted but it is clear that geometric effects can contribute significantly to the observed variations of rayleigh and love wave amplitudes this is the probable explanation for the instability of q estimates made from surface waves other source regions producing large surface wave amplitude anomalies include japan and southeastern alaska

miocene deepwater oceanography a global synthesis of miocene benthic foraminiferal carbon and oxygen isotopic and faunal abundance data indicates that miocene thermohaline circulation evolved through three regimes corresponding approximately to early middle and late miocene times there is evidence for major qualitative differences between the circulation of the modern ocean and the miocene ocean prior to 11 ma the 13c 12c ratios of the benthic foraminifera cibicidoides are interpreted in terms of water mass aging i e the progressive depletion of dissolved o2 and lowering of 13c values as the result of oxidation of organic matter as water flows further from its sources at the surface of the oceans both isotopic and faunal data indicate that the early miocene regime from 22 to 15 ma was the most different from today s during that interval intermediate and deep waters of both the atlantic and the pacific oceans aged in a northward direction and the intermediate waters of the indian the south atlantic and the south pacific oceans were consistently the youngest in the global ocean we speculate that early miocene global thermohaline circulation may have been strongly influenced by the influx of warm saline water tethyan indian saline water from the tethys into the northern indian ocean the isotopic and faunal data suggest that flow from the tethyan region into the indian ocean diminished or terminated at about 14 ma isotopic and faunal data give no evidence for north atlantic deep water nadw formation prior to about 14 5 ma with the exception of a brief episode in the early miocene from 14 5 to 11 ma nadw formation was weak and circumpolar and antarctic water flooded the deep south atlantic and south pacific as the antarctic ice cap grew from about 10 ma to the end of the miocene thermohaline circulation resembled the modern circulation in many ways in latest miocene time 6 to 5 ma circulation patterns were very similar to today s except that nadw formation was greatly diminished the distribution pattern of siliceous oozes in miocene sediments is consistent with our proposed reconstruction of thermohaline circulation major changes which occurred in circulation during the middle miocene were probably related to the closing of the tethys and may have contributed to rapid middle miocene growth of the antarctic ice cap appendices 1 4 6 and 7 are available withentire article on microfiche order fromamerican geophysical union 2000 floridaavenue n w washington dc 20009 document 88p 002 5 00 payment mustaccompany order

paleocurrent reconstruction of the deep pacific inflow during the middle miocene reflections of east antarctic ice sheet growth today the deep western boundary current dwbc east of new zealand is the most important route for deep water entering the pacific ocean large scale changes in deep water circulation patterns are thought to have been associated with the development of the east antarctic ice sheet eais close to the main source of bottom water for the dwbc here we reconstruct the changing speed of the southwest pacific dwbc during the middle miocene from 15 5 12 5 ma a period of significant global ice accumulation associated with eais growth sortable silt mean grain sizes from ocean drilling program site 1123 reveal variability in the speed of the pacific inflow on the timescale of the 41 kyr orbital obliquity cycle similar orbital period flow changes have recently been demonstrated for the pleistocene epoch collectively these observations suggest that a strong coupling between changes in the speed of the deep pacific inflow and high latitude climate forcing may have been a persistent feature of the global thermohaline circulation system for at least the past 15 myr furthermore long term changes in flow speed suggest an intensification of the dwbc under an inferred increase in southern component water production this occurred at the same time as decreasing tethyan outflow and major eais growth between 15 5 and 13 5 ma these results provide evidence that a major component of the deep thermohaline circulation was associated with the middle miocene growth of the eais and support the view that this time interval represents an important step in the development of the neogene icehouse climate

rupture process of the march 3 1985 chilean earthquake the march 3 1985 central chile earthquake ms 7 8 ruptured a well studied seismic gap along the chilean subduction zone the epicenter of this event is located near the center of an approximately 300 km long region which ruptured in a great event in 1906 mw 8 2 the northern portion of the 1906 zone has since ruptured in 1971 ms 7 5 and 1973 ms 6 7 we have determined the rupture history of the 1985 central chile earthquake from the deconvolved source functions of body waves both p and pp the source functions show one major pulse of moment release the onset of which occurs about 16 seconds after an initial small pulse the azimuthal directivity in the p waves indicates that the rupture front propagated from the epicenter southward and that the moment release of the major pulse is concentrated in a region between the epicenter and approximately 75 km south of the epicenter we conclude that the region of high moment release is the dominant asperity and was loaded by slip in the relatively weaker northern region

focal depths and moment tensor representations of shallow earthquakes associated with the great sumba earthquake focal depths in the range 8 to 24 km below the seafloor were determined for seven of the larger shocks associated with the great sumba earthquake of august 19 1977 depth control was achieved by modeling digitized long period p waves recorded by the world wide standard seismic network if the base of the rupture at the time of the mainshock were no greater than the depth of the deepest aftershock the stress drop would be nearly 500 bars amplitude and first motion data from the p waves were inverted for point source moment tensors the inversion of rayleigh and love wave spectra computed from digital seismograms recorded by the seismic research observatories sro and the abbreviated seismic research observatories asro broadened the source study to include earthquakes with moments as small as 1024 dyn cm too small for either traditional first motion solutions or p wave modeling the inversion procedure was applied to data in the passband from 30 to 120 s the propagation phase for the love and the rayleigh waves was calibrated with signals from two earthquakes for which the source phase was inferred from the p wave solutions agreement with the corresponding p wave solutions is nearly the same whether or not the smaller eigenvalues of the inner product matrix are retained in the inversions the double couple components generally account for more than two thirds of the total moment normal faulting along an east to northeasterly strike characterizes the mechanisms in the principal zone of aftershock activity strike slip mechanisms consistent with horizontal compression normal to the arc prevail in the delayed aftershock zone located 200 km northwest of the mainshock of the earthquakes subjected to this surface wave analysis the foreshock stood out as having felt a significantly higher apparent stress perhaps as much as one half an order of magnitude higher than the others these results suggest that accurate source parameters for moderate to small magnitude earthquakes can be determined from surface waves recorded by the sro and asro in particular the mechanisms of small magnitude foreshocks could be obtained in this way

effects of lateral heterogeneity and source process time on the linear moment tensor inversion of long period rayleigh waves spectra of mantle rayleigh waves recorded on the ida network are inverted to determine the seismic moment tensor of the 9 june 1980 california mexico border earthquake the 29 july 1980 vanuatu islands earthquake and the 9 july 1980 santa cruz islands earthquake examinations are made to correct for phase velocity lateral heterogeneity and source process time a simple regionalization stable continent tectonic region young ocean and old ocean improves results of the linear inversion but the phase correction is not large enough and the discontinuous change of phase velocity across the boundary between regions causes an artificial rapid change in apparent phase velocity as a function of azimuth therefore a more detailed but gradual representation of the lateral heterogeneity is desirable to correct for the propagation effect in the linear inversion a source process time which consists of the nondirectional part of the apparent duration of main faulting and the delay time of the faulting from initial break is estimated by a phase analysis of rayleigh waves the source process time is generally proportional to the seismic moment on the log log scale but some earthquakes deviate considerably from the general relation therefore the measurement of the source process time should be made before the moment tensor inversion the phase errors introduced by the lateral heterogeneity and source process time may cause a bias to low scalar moment

lateral heterogeneity in continents moment tensor inversion of long period surface waves and depth resolution of crustal events body wave modeling and phase velocity calibrations

monitoring of strain release in central and northern california using broadband data systematic cataloguing of seismic moment depth and mechanism of regional earthquakes down to magnitude m 4 can now be achieved in close to real time using data from sparse networks of digital broadband stations the procedure we have developed relies on 3 independent methods for the determination of moment tensor providing confidence limits on the results we show the results of application to the seismicity in central and northern california for a one year period starting in march 1992 and illustrate how patterns of stress and strain release can now be monitored systematically and reliably in a timely fashion

unlocking the ice house oligocene miocene oxygen isotopes eustasy and margin erosion oxygen isotope records and glaciomarine sediments indicate at least an intermittent presence of large continental ice sheets on antarctica since the earliest oligocene circa 35 ma the growth and decay of ice sheets during the oligocene to modern ice house world caused glacioeustatic sea level changes the early eocene was an ice free greenhouse world but it is not clear if ice sheets existed during the middle to late eocene doubt house world benthic foraminiferal 18o records place limits on the history of glaciation suggesting the presence of ice sheets at least intermittently since the earliest oligocene the best indicator of ice growth is a coeval increase in global benthic and western equatorial planktonic 18o records although planktonic isotope records from the western equatorial regions are limited subtropical planktonic foraminifera may also record such ice volume changes it is difficult to apply these established principles to the cenozoic 18o record because of the lack of adequate data and problems in stratigraphic correlations that obscure isotope events we improved oligocene to miocene correlations of 18o records and erected eight oxygen isotope zones oi1 oi2 mi1 mi6 benthic foraminiferal 18o increases which are associated with the bases of zones oil circa 35 8 ma oi2 circa 32 5 ma and mil circa 23 5 ma can be linked with 18o increases in subtropical planktonic foraminifera and with intervals of glacial sedimentation on or near antarctica our new correlations of middle miocene benthic and western equatorial planktonic 18o records show remarkable agreement in timing and amplitude we interpret benthic planktonic covariance to reflect substantial ice volume increases near the bases of zones mi2 circa 16 1 ma mi3 circa 13 6 ma and possibly mi5 circa 11 3 ma possible glacioeustatic lowerings are associated with the 18o increases which culminated with the bases of zone mi4 circa 12 6 ma and mi6 circa 9 6 ma although low latitude planktonic 18o records are required to test this these inferred glacioeustatic lowerings can be linked to seismic and rock disconformities for example we link 12 oligocene early late miocene inferred glacioeustatic lowerings with 12 of the sequence boundaries inferred eustatic lowerings of haq et al 1987

charcoal analysis and dendrology data from archaeological sites in north western france during the last 15 years charcoal analysis of archaeological sites in north western france has been carried out in conjunction with systematic and detailed dendrological examination by considering these extrinsic criteria in association with the analytical results palaeo ethnographic and palaeo environmental information can be obtained the charcoals are classically identified under the microscope on the basis of their cellular structure this examination is associated with an observation of the ligneous structure on transverse sections using a binocular lens when charcoal fragments are large enough the growth ring widths are measured tree ring curvature is also noted finally alteration by fusion or radial cracks the presence of fungal hyphae and insect degradation are also recorded results are thus obtained on the nature of fuel used in domestic fireplaces and kilns the selection of timbers and their catchment areas are also revealed the average width of the growth rings in oak charcoal from domestic hearths coming from about forty sites in north western france shows a significant increase from 6000 to 2000 bp there is a similar increase in the number of heliophilic taxa used from the neolithic to the iron age this implies that the environment became more and more open because of use by society the interpretation of the dendrology results applied to charcoal analyses is obtained through a convergence of criteria thus charcoal analysis can provide more than just an identification of the species used and can yield fundamental information on the interaction of society with the environment

benthic foraminiferal evidence for the existence of an early miocene oxygen depleted oceanic water mass this study presents new data derived from changes in benthic foraminiferal assemblages between 24 and 8 ma in the atlantic and indian oceans which are integrated with published stable isotope and fauna1 records we have identified an intermediate to deep water mass which was lower in oxygen and was restricted to the nw indian atlantic and the tethys mediterranean oceans our interpretations are based on the coeval occurrences 19 5 16 5 ma of high abundances of smooth walled bolivinids in these oceans our observations agree with the interpretations of previous workers for the occurrence of tethys derived intermediate and deep water in the northern indian ocean between 24 and 14 ma and for northern component water production in the atlantic ocean between 20 and 16 ma the water mass defined by these bolivinids formed a southward flowing northern component water in the atlantic ocean and contributed via tethys to the intermediate and deep water input into the indian ocean

cenozoic bottom current sedimentation in the cape basin south atlantic the cape basin is located at a central location with respect to variouswater masses the coldest and densest of these water masses is thelower circumpolar deep water the location and topography of the agulhas ridge effectively blocks itsnorthward flowing branches and deflects them into a south westerndirection to follow the bathymetric contours of the agulhas ridge wheresuspended sediments accumulate in contourite drifts several hundred metres of sediments have accumulated since the onsetof antarctic bottom water intrusion into the basins of the south atlantic a present day like bottom current following agulhas ridge contours existssince an erosional event in the early oligocene took place which markeda prominent change in sedimentation strong and varying currents in the early oligocene formed a sheet likedeposition at high sedimentation rates the fluctuating types of sediments produce strong seismic reflections it was followed by a very stable unidirectional bottom current with mainlymuddy sediments this resulted in the formation of a more than 200 kmlong approx 30 km wide elongate contourite drift which shows fewinternal reflections on the seismic data an increase of well defined unitsis found after a period of non deposition in the middle miocene still the build up of the drift structure continued but at places erosion isfound especially in quaternary sediments and probably in relation toglaciation cycles

notes on southern ocean hydrography sea ice and bottom water formation abstract the southern ocean circulation and sea ice distribution is briefly described the formation of extremely cold bottom water in the weddell sea and its relation to the floating ronne filchner ice shelves is discussed it is shown that a concentrated swift eroding bottom current with anomalous low 18 o ratio transports the cold and dense ice shelf water from the shelf towards large depths comments are made on possible implications of this process for the large scale deep water circulation and for the interpretation of sediment cores

impact of weddell sea shelf progradation on antarctic bottom water formation during the miocene the weddell sea is a main location of bottom water formation and thus an important component of global ocean circulation in this study we examine the ocean and climatic responses to a shelf progradation induced by ice sheet advance and glacially transported sediments during the miocene using a general circulation model our investigations show that relative to a miocene standard bathymetry a farther southerly placed shelf break as reconstructed in a state of the art bathymetry for the weddell sea enables enhanced antarctic bottom water aabw formation and gyre transport during the middle miocene for both relatively high and low atmospheric co2 concentrations furthermore co2 sensitivity experiments show that an atmospheric co2 decline for a setup with the southerly placed shelf break of a new bathymetry has only a minor impact on aabw formation while the standard setup shows an increase in combination these impacts may explain the pronounced deep water formation in the southern high latitudes from the middle miocene to the late miocene

empirical measurements of tectonic moment release in nuclear explosions from teleseismic surface waves and body waves summary a method of source parameter estimation based principally on observations of teleseismic long period surface waves is developed and applied to 71 underground nuclear explosions at the balapan shagan river test site in kazakhstan first we quantify the observed radiation patterns of love and rayleigh waves noting that such data place only three linear constraints on the five parameters of the standard point source model for each explosion the three constraints are the strengths of the isotropic sin2 and cos2q components of the observed pattern where is azimuth the five source parameters are the isotropic moment m the doublecouple moment adt and the strike dip and rake angles qs 6 a these last four parameters characterize the inferred faulting tectonic release surface waves which propagate from different seismic events in a geographically tight cluster to a distant station are similar in shape and for very shallow sources the propagation operator can be described by a single wave shape a differential propagation delay and a single amplitude factor containing the effects of attenuation scattering focusing and geometrical spreading the inverse problem is formulated which iteratively solves simultaneously for the path amplitude factors and the three radiation pattern parameters for all events using observed seismograms as the empirical wave shapes we fit 1110 relative measurements of rayleigh and love wave amplitudes to determine path amplitude factors to 29 globally distributed stations and radiationpattern parameters for the 71 explosions second we present a new method for interpreting such radiation patterns in previous studies two of the five source parameters have typically been fixed by making the very restricted assumption of pure dip slip faulting at 45 dip the assumption leads to estimates of strike that are mostly in the north west south east direction at balapan and to estimates of m that correlate very poorly with estimates based upon short period signals p lg however now that excellent yield estimates have become available we can avoid the assumption of pure dip slip faulting instead we can estimate mi from p and lg wave data thus adding a fourth constraint to help in interpreting the teleseismic surface wave amplitudes the outcome is a method for estimating the strike as of faulting associated with tectonic release for each explosion and for estimating the two combinations m sin 6 cos a and mo sin 26 sin a which respectively are the strike slip and dip slip components of the tectonic release the strike directions of inferred faulting at balapan are found to lie in the range 90 120 which conforms better with limited geological information on faulting in the region than does the trend that has long been inferred from assuming pure dip slip faulting we find that without additional information about individual explosions we are not able to provide a high precision isotropic moment or yield estimate from teleseismic surface waves

seismic potential for large and great interplate earthquakes along the chilean and southern peruvian margins of south america a quantitative reappraisal the seismic potential of the chilean and southern peruvian margins of south america is reevaluated to delineate those areas or segments of the margin that may be expected to experience large or great interplate earthquakes within the next 20 years 1984 2004 long term estimates of seismic potential or the conditional probability of recurrence within a specified period of time are based on 1 statistical analysis of historic repeat time data using weibull distributions and 2 deterministic estimates of recurrence times based on the time predictable model of earthquake recurrence both methods emphasize the periodic nature of large and great earthquake recurrence and are compared with estimates of probability based on the assumption of poisson type behavior the estimates of seismic potential presented in this study are long term forecasts only as the temporal resolution or standard deviation of both methods is taken to range from 15 to 25 of the average or estimated repeat time at present the valparaiso region of central chile 32 35 s has a high potential or probability of recurrence in the next 20 years coseismic uplift data associated with previous shocks in 1822 and 1906 suggest that this area may have already started to rerupture in 1971 1973 average repeat times also suggest this area is due for a great shock within the next 20 years flanking segments of the chilean margin coquimbo illapel 30 32 s and talca concepcion 35 38 s presently have poorly constrained but possibly quite high potentials for a series of large or great shocks within the next 20 years in contrast the rupture zone of the great 1960 earthquake 37 46 s has the lowest potential along the margin and is not expected to rerupture in a great earthquake within the next 100 years in the north the seismic potentials of the mollendo arica 17 18 s and arica antofagasta 18 24 s segments which last ruptured during great earthquakes in 1868 and 1877 are also high but poorly constrained

depositional processes and growth patterns of isolated oceanic basins the protector and pirie basins of the southern scotia sea antarctica abstract sedimentary processes in small isolated oceanic basins that form adjacent to continental margins but detached from continents remain poorly understood this work describes two such basins located in the southern scotia sea the protector and pirie basins we analysed multichannel seismic profiles to interpret morphostructural features and stratigraphy of these basins sedimentary stacking patterns and depocentre distribution illustrate basin development patterns basal units infill basement depressions formed by the submerged banks of thinned continental crust that abut the basin plains these lower and middle deposits of the sedimentary record are interpreted as pre and syn rift deposits the laterally extensive upper deposits are interpreted as post rift deposits these include five discrete units evident in seismic profiles a prominent regional reflection referred to as reflector c separates in these upper deposits two sets of seismic units that have recorded major shifts in the dominant sedimentary processes stacking patterns and paleo environmental conditions the most important processes controlling deposition of the older units those beneath reflector c include down slope gravity processes that infill depressions created by crustal thinning and seafloor spreading these occurred under the coeval influence of circumpolar deep water circulation the major processes influencing younger units those above reflector c include bottom water circulation of the circumpolar deep water and weddell sea deep water water masses which coursed along bathymetric contours of the seafloor the reflector c discontinuity developed concurrently with middle miocene tectonic changes which led to the opening and deepening of deep gateways in the south scotia ridge these facilitated overflow of weddell sea deep water from the weddell gyre into the scotia sea this overflow in turn forced the circumpolar deep water northwards analysis of the protector and pirie basins shows that their tectonic evolution influenced regional deep water circulation patterns in an area that makes a significant cold water contribution to the global conveyor belt system as a long term factor controlling basin evolution and sedimentary processes tectonics events in this region therefore influenced the present day climate system these results further clarify our understanding of deep isolated oceanic basins in terms their sedimentologic climatologic and oceanographic significance