a continuum of stress strength and slip in the cascadia subduction zone movement of the down going oceanic plate in subduction zones is accommodated by earthquakes slow slip and free slip with increasing depth analysis of accompanying tremor reveals a continuum of slow slip events in the cascadia subduction zone which suggests that deep free slip of the subducted plate may cause stress to be gradually transferred up the plate interface towards the seismogenic zone

esr dating of tooth enamel from aterian levels at mugharet el aliya tangier morocco abstract electron spin resonance esr dating has been carried out on ungulate tooth enamel samples from the pleistocene deposits of mugharet el aliya atlantic coastal morocco age estimations for wave induced breaching of the cavity and initial sand deposition layer 10 are 62 6 ka bp by the early uptake eu model and 81 9 ka bp by linear uptake lu samples from aterian occupations in layers 5 and 6 and a possible occupation in layer 9 yielded eu estimated ages between 39 4 and 44 5 ka bp and lu ages between 47 5 and 56 5 ka bp incorporating the entire range of eu and lu model ages the aterian occupations are dated to between 35 and 60 ka bp when compared with the published mostly radiocarbon based ca 40 20 ka bp chronology for the moroccan aterian e g debenath 1992 these new results imply an aterian arrival or mousterian to aterian transition occurring beyond the upper limit of the radiocarbon method

elevation changes and the great 1960 chilean earthquake support for aseismic slip we reanalyse the near field vertical displacement data for the great chilean earthquake of 1960 to provide constraints on the down dip slip distribution a recent study of free oscillation data confirms earlier proposals of a slow precursor comparable in size to the main shock we seek evidence for this event in the displacement data spatial coverage of the data is inadequate to allow determination of a unique fault model but inversions show that thrust slip must extend over a width of about 300 km and to a depth between 60 km and 85 km well below the seismogenic zone for interplate events we propose that this deeper slip is the source of the slow event our preferred class of solutions has moments ranging from 1 6 1023 n m to 2 5 1023 n m only 30 to 45 of the free oscillation value underestimation of the near trench displacements by 50 together with a seismic overestimation of moment by 30 due to tradeoff with rise time would result in satisfactory agreement

observed deep anticyclonic cap over caiwei guyot the mean circulation pattern and its mechanism over caiwei guyot 1308 5600 m in the northwest pacific were studied utilizing three years of in situ data a deep anticyclonic cap was found to enclose the entire guyot from its bottom up to a depth of 728 m which is comprised of a stable but highly asymmetric anticyclonic circulation at the foot and a bottom trapped anticyclonic circulation over the summit on the slope the circulation is complex with a dominant anticyclonic circulation near the bottom and a weak cyclonic circulation at 2200 m the anticyclonic cap intensity over the summit is significantly modulated by the time varying impinging flow an intensified cold ring above the summit edge was observed at caiwei guyot which differs from the cold domes observed over traditional conic seamounts further analysis suggests that the impinging flow is primarily responsible for the cap formation and the m2 tide seamount interaction plays a secondary role the anticyclonic cap may play a role in the local geological distribution

a possible model for large preseismic slip on a deeper extension of a seismic rupture plane abstract i develop a numerical model for preseismic slip and episodic aseismic slip events slow earthquakes on a deeper extension of a seismogenic plate interface using a rate and state dependent friction law the deep preseismic slip and episodic slow slip were indicated by models based on geodetic observations though they cannot be explained by common rate and state dependent laws i investigate whether this incongruity can be removed by including use of additional known constraints on the frictional property the steady state friction on a model fault is taken to be velocity weakening at low velocities and velocity strengthening at high velocities the transition velocity from velocity weakening friction to velocity strengthening is assumed to be the seismic slip velocity at shallow seismic depths and decreases with depth at deeper parts simulation results for a 2d model of interplate earthquakes at a subduction zone are as follows 1 during an interseismic period between successive large earthquakes at shallow seismogenic depths some episodic aseismic slip events with durations of a few years occur on the plate interface just below the seismogenic depths 2 preseismic slip occurs at nearly the same location where the episodic aseismic slip events occur these may explain some characteristics of observed preseismic slip of the 1944 tonankai earthquake m 7 9 along the nankai trough central japan and episodic aseismic slip events in the same area

spherical versus flat models of coseismic and postseismic deformations we perform an exhaustive study of coseismic and postseismic surface deformations induced by shear dislocations using flat and spherical earth models our aim is to examine the effects of the spherical geometry the vertical layering and the self gravitation on surface displacement field for a 100 km long fault spherical and flat models produce comparable coseismic deformations up to a distance of 300 km from the epicenter this distance is sensibly reduced in the postseismic regime and when infinitely long strike slip faults are considered the differences between predictions based on flat and spherical models are due both to their global geometry and the effect of the gravity forces self gravitation has a minor role with respect to that of sphericity for surface coseismic deformations while in the postseismic regime its effects increase considerably as a case study we consider the coseismic and postseismic deformations due to the great 1960 chilean earthquake the results of the spherical stratified model differ sensibly from those of a flat uniform model moreover within the framework of spherical earth models the rheological stratification plays a major role in determining the pattern of the displacement field we show that the present day rates of vertical and horizontal deformations are considerably large 10 2 m yr 1 for an asthenospheric viscosity ranging from 10 19 to 10 20 pa s these rates which could possibly be detected by geodetic investigations are found to be also sensitive to the rheological properties of the mantle beneath the asthenosphere

a slow earthquake sequence on the san andreas fault earthquakes typically release stored strain energy on timescales of the order of seconds limited by the velocity of sound in rock over the past 20 years observations1 13 and laboratory experiments14 have indicated that rupture can also occur more slowly with durations up to hours such events may be important in earthquake nucleation15 and in accounting for the excess of plate convergence over seismic slip in subduction zones the detection of events with larger timescales requires near field deformation measurements in december 1992 two borehole strainmeters close to the san andreas fault in california recorded a slow strain event of about a week in duration and we show here that the strain changes were produced by a slow earthquake sequence equivalent magnitude 4 8 with complexity similar to that of regular earthquakes the largest earthquakes associated with these slow events were small local magnitude 3 7 and contributed negligible strain release the importance of slow earthquakes in the seismogenic process remains an open question but these observations extend the observed timescale for slow events by two orders of magnitude

low frequency source characteristics of the great 1960 chilean earthquake the low frequency nature of the great 1960 chilean earthquake the earth s largest recorded event is characterized and a source model composed of three events with a combined seismic moment of 5 5 1023 n m and a duration of 1500 s is presented the results show conclusively that large scale slip which is only observed at low frequencies preceded the main shock complex amplitude measurements of normal mode data in the band 1 0 5 0 mhz recorded at eight vertical component stations comprise the data set in this band the earthquake source is assumed to be described by a line source propagating at a constant rupture velocity the data set is the basis for a sequence of least squares inversions to determine the seismic moment rupture velocity spatial slip distribution and the temporal slip function the data are best explained by a source model that begins 1150 s before the main shock with an event of moment 1 9 1023 n m and rise time of 300 s a main shock with moment of 3 2 1023 n m and for which most of the low frequency energy was released beginning about 50 s after the short period origin time and an event 350 s later with moment of 0 4 1023 n m the uncertainty in the moment estimate of the great 1960 chilean earthquake is about 50 and is due primarily to the probable range of fault plane dip which is not well constrained at this time

osl dating of the aterian levels at dar es soltan i rabat morocco and implications for the dispersal of modern homo sapiens the aterian is a distinctive middle palaeolithic industry which is very widely spread across north africa its dating and significance have been debated for nearly a century renewed interest in the aterian has arisen because of a recent proposal that its development and spread may be linked to the dispersal of anatomically modern humans the industry contains technological innovations such as thin bifacially flaked lithic points and pedunculates as well as evidence for personal ornaments and use of red ochre such markers as shell beads are believed to be indicative of symbolic behaviour dar es soltan i on the atlantic coast of morocco contains a thick sequence of aterian deposits that were thought to represent the later stages of development of this industry new optically stimulated luminescence dates and geomorphological study indicate a much older sequence and so far the earliest yet recorded ages for the aterian they suggest an appearance in the maghreb region during mis marine isotope stage 5

aterian lithic technology and settlement system in the jebel gharbi north western libya the aterian represents one of the multiple facets of the middle stone age msa and has become increasingly important in the context of understanding modern human origins in this paper we present the results of our study on the aterian in the jebel gharbi north western libya from a regional point perspective a total of 1567 lithic objects were analysed for this work from twelve different aterian assemblages the results of this analysis show a wide range of economic behaviour possibly suggesting different site functions within the three main areas ain zargha jefara and wadi ghan it is unlikely that any of these assemblages represents a residential site instead we argue that the assemblages in the study are more likely to be the result of a logistic land use technologically they exhibit all the distinctive features of the aterian technocomplexes coexistence between levallois and blade technology presence of tanged pieces and bifacial foliates as well as of upper palaeolithic tools together with a majority of sidescrapers and endscrapers only a combination of these features and certainly not one of them alone can characterize an assemblage as aterian

africa and iberia in the pleistocene abstract the strait of gibraltar would logically seem to be a major point of contact between africa and europe yet controversy about possible trans gibraltar human movements in the lower middle and even upper pleistocene has reigned for over a century and continues to do so imbricated with biogeographical arguments about faunal transfers and the creation of hominid niches in iberia the problem of the relationships between africa and iberia is one of the knottiest in stone age prehistory did early homo h ergaster erectus or antecessor cross into iberia from the maghreb as has long been argued on the basis of general archeological similarities this old hypothesis still unproven is made somewhat more plausible by the re dating of the site of ain hanech in algeria and in particular by the spectacular lower pleistocene fossil and artifactual discoveries at atapuerca in north central spain and less securely in the guadix baza basin of granada middle pleistocene contacts remain problematic with direct peopling of iberia from northwest africa during the mid upper pleistocene seeming ironically to be out of the question as southern spain and portugal were one of the last refugia of neanderthals using mousterian technology despite proximity to the putative source of anatomical modernity and cultural superiority similarly despite years of speculation on a migrationist cause for the similarity between tanged points in the aterian of north africa and in the solutrean of mediterranean spain and portugal the chronological and archeological data solidly disprove this seductive hypothesis for the upper pleistocene it is only in the terminal paleolithic that with clear evidence of marine fishing and probable navigation a credible case can be made for trans gibraltar human contacts

context of modern human occupations in north africa contribution of the temara caves data el harhoura 2 and el mnasra caves are located in the region of temara on the atlantic coast of morocco which was occupied by human populations since the beginning of the late pleistocene around 120 ka bp until the middle holocene around 6 ka bp recent excavations yielded human and faunal remains as well as exceptional archaeological objects middle upper palaeolithic and neolithic industries ceramics ornaments in nassarius sp shells bone tools pigments associated with anthropic structures the continuous sedimentary sequence of these sites covers the last climatic cycle from the eemian interglacial to the present one and is studied in a renewed context from several points of view geology stratigraphy chronology cultures anthropology palaeontology taphonomy and zooarchaeology today there is no equivalent of such regional data for the whole late pleistocene in north africa the study of small and large faunal remains associated with chronological data allowed us to obtain significant data on palaeoenvironments and human carnivore occupations of the temara caves these data are included in a broader view of human occupations and their environmental context throughout north africa during the late pleistocene and holocene

imaging of aseismic fault slip transients recorded by dense geodetic networks summary the large scale continuous gps networks that have emerged in the last decade have documented a wide range of aseismic deformation transients that resulted from physical processes such as aseismic fault slip and magma intrusion in particular a new class of m 7 slow earthquakes with durations ranging from days to months have been observed with gps arrays located above the downdip portion of subduction zone thrust interfaces interpretation of the displacement time series resulting from these events is not straightforward owing to the contaminating effects of multiple contributing signals such as fault slip local benchmark motion seasonal effects and reference frame errors we have developed a time dependent inversion algorithm based on the extended kalman filter which can separate the various signals and allow the space time evolution of these slow slip transients to be studied in detail we applied the inversion algorithm to the 1999 cascadia slow earthquake this event had two primary episodes of moment release separated by a two week period in which relatively little moment release occurred the cascadia event and other slow earthquakes share numerous similarities with both ordinary earthquakes and afterslip transients suggesting that they may represent fault slip under a conditionally stable regime

palhydaf palaeohydrology in africa program objectives methods major results abstract the palhydaf program aims to reconstruct the late quaternary 130 ka b p to present environmental and hydrological changes of northwest africa and to interpret them in terms of palaeoclimate for testing coupled atmospheric ocean circulation models lacustrine sequences were obtained from closed basins which lie along two meridional transects southern tunisia southern niger and algeria mali particular attention is given to groundwater storage and periods of recharge of the aquifers the chronological framework is based on 14c dates conventional and ams methods and or the th u disequilibrium method in favourable cases e g mali correlations can be made between the chronology of surface palaeohydrology and that of aquifer recharge various environmental markers mineralogy elemental chemistry stable isotopes biological remains are used for palaeoenvironmental purposes quantitative estimates of palaeoclimatic variables e g air humidity may be attempted through the combination of geochemical and palaeobiological data the major results already obtained are summarized for the following individual sectors 1 southern tunisia 1 northern algeria 2 southern algeria 3 northern niger 3 mali 4 southern niger at the present stage of investigation the following new inferences can be drown one or several humid episode s occurred in the northern sahara between 150 and 75 ka b p several factors suggest that these humid conditions also affected lower latitudes although their southern extent cannot be given precisely at present the previously postulated existence of large lakes at 20 35 ka b p is not confirmed this time interval seems to coincide with raised water tables but not to a major humid phase in all cases the 14c chronologies obtained for the late pleistocene have to be checked by comparison with other dating methods e g th u disequilibrium after the arid period of the last glacial maximum the return of humid conditions occurred in two major steps at 12 and 9 5 9 ka b p for both the southern and the northern sahara

a 4500 year record of emergence events at onnetoh hokkaido northern japan reconstructed using plant macrofossils abstract plant macrofossils vascular plants and mosses document six episodic emergence events during the late holocene at onnetoh eastern hokkaido northern japan four events were dated by the ams radiocarbon method to 4240 3910 3640 3360 1520 1260 and 790 660 cal year bp and another was dated by liquid scintillation spectrometry of radiocarbon to 2750 2430 cal year bp we attribute the three most recent and the two oldest periods of emergence events identified in this study to uplift associated with unusually large interplate earthquakes along the southwestern part of the kuril subduction zone

chronology and formation processes of the middle to upper palaeolithic deposits of ifri n ammar using multi method luminescence dating and micromorphology abstract the existence of an early upper palaeolithic culture at the transition from the middle palaeolithic to the upper palaeolithic in north african cave sites is currently under debate we studied ifri n ammar in north east morocco which is one of the oldest settlement sites of anatomically modern humans amh in the maghreb and contains several sediment layers which are attributed to middle and upper palaeolithic occupations in order to investigate processes of sediment accumulation and postdepositional alteration we studied thin sections from these levels according to micromorphological analysis aeolian input considerably contributed to sediment accumulation and postdepositional mixing by bioturbation occurred we compared multiple and single grain quartz and multiple grain feldspar luminescence dating of three samples from corresponding sediment layers to achieve a comprehensive chronology the single grain dose distributions scatter strongly and the source of the scatter is unclear we used an arithmetic mean to calculate the equivalent doses archaeological evidence and age control from radiocarbon dating was essential to interpret the data quartz and feldspar multiple grain luminescence ages are between 15 and 80 ka the central part of the profile shows an intermediate accumulation which lacks specified lithic artefacts this supports the idea of an occupational gap between middle and upper palaeolithic layers

molecular stratigraphy of cores off northwest africa sea surface temperature history over the last 80 ka the molecular stratigraphy of biogeochemical oceanic flux study core 31k 19 n 20 10 w and ocean drilling program hole 658c 20 45 n 18 35 w has been studied for c37 alkenone abundances over the past 80 ka at high resolution circa 200 500 years the derived uk37 sea surface temperature record for both cores shows a range of temperatures from about 18 c during the last glacial to 21 5 c during the early holocene both records also reveal changes in sea surface temperature as much as 2 4 c over a few hundred years which correlate well with similar abrupt climatic changes observed in cores from elsewhere in the ne atlantic associated with heinrich events our results indicate that meltwater produced by these ice rafting events was transmitted southward by the canary current where it had considerable impact on sea surface temperatures in the subtropical eastern atlantic

episodic aseismic earthquake precursors shallow earthquakes are generally believed to be brittle fractures in a stressed medium with rupture velocity at a speed close to that for shear waves we know however that the earth allows failure over a wide range of timescales creep events occur on the san andreas fault system and for some earthquakes the high speed rupture is accompanied by a slower process1 5 here we report on episodic slow events which occurred before the japan sea earthquake of magnitude 7 7 on 26 may 1983 a sacks evertson borehole strain meter6 90 km from the earthquake recorded about 100 aseismic strain events in a five month period before and immediately following the earthquake none has been detected after the large aftershocks the observed signals are consistent with a precursory redistribution of stress through aseismic slip on a deep extension of the main shock fault plane such episodic aseismic events may provide a mechanism for relatively rapid stress concentration before earthquakes

extremely large variations of atmospheric 14c concentration during the last glacial period a long record of atmospheric 14c concentration from 45 to 11 thousand years ago ka was obtained from a stalagmite with thermal ionization mass spectrometric 230th and accelerator mass spectrometric 14c measurements this record reveals highly elevated 14c between 45 and 33 ka portions of which may correlate with peaks in cosmogenic 36cl and10be isotopes observed in polar ice cores superimposed on this broad peak of 14c are several rapid excursions the largest of which occurs between 44 3 and 43 3 ka between 26 and 11 ka atmospheric 14c decreased from 700 to 100 per mil modulated by numerous minor excursions carbon cycle models suggest that the major features of this record cannot be produced with solar or terrestrial magnetic field modulation alone but also require substantial fluctuations in the carbon cycle

late cenozoic micromammal biochronology of northwestern africa abstract this synthesis aims to integrate former recent and unpublished data on fossil micromammals rodentia erinaceomorpha soricomorpha chiroptera from moroccan algerian and tunisian archeological and paleontological sites an updated biochronology of these taxa is established from the middle miocene to the holocene ten main biozones are defined they are characterized by specific faunal assemblages whose evolution and migrations were influenced by geologic and climatic events throughout the studied period during the miocene myocricetodontinae were dominant this period was followed by a progressive diversification among murinae gerbillinae and crocidurinae from the plio pleistocene onwards along with sporadic occurrences of european asian and sub saharan taxa before a decrease in small mammal diversity at the beginning of the late pleistocene while modern faunas stabilized overall the new biochronology matches well with the former ones however some slight discrepancies emerge notably because the former biochronologies were based on more sporadic data and often did not consider the whole small mammal faunas the present work represents the first complete biochronological synthesis of north african small faunas for the whole late cenozoic which should be useful for paleontologists and archeologists in providing an up to date framework into which future discoveries will easily find their place

postseismic relaxation theory on the spherical earth abstract postseismic displacements and strains observed at the earth9s surface can be explained through the relaxation of a viscoelastic asthenosphere underlying a purely elastic crust a theory is presented for modeling the effects of postseismic relaxation on a spherically symmetric earth for an earthquake point source located in the upper elastic layer the displacement field is decomposed into its toroidal and spheroidal components a linear maxwell rheology in the viscoelastic layers is assumed enabling the use of the correspondence principle for the solutions of the equations of static equilibrium displacement and strain fields are then calculated using normal mode summation computational results are presented for two simple earthquake sources a strike slip fault and a uniaxial thrust fault the patterns of postseismic displacements and strains are found to depend strongly on both the earth model and earthquake source geometry in particular the elastic plate thickness asthenosphere thickness fault type and fault length each play a major role in determining the spatial pattern of postseismic relaxation effects asthenospheric viscosity controls the temporal pattern of relaxation

the 1960 chilean earthquakes an unusual foreshock sequence that began with an earthquake of moment 2 0 1021 n m and rupture length of about 150 km preceded the great 1960 chilean earthquake earthquake relocations of the sequence show a progression of seismic activity toward the initiation of the main shock the rupture length of the great 1960 chilean earthquake is estimated from the distribution of aftershocks and crustal deformation to be 920 100 km the source mechanisms of a foreshock and two aftershocks are determined and used to constrain the source mechanism of the main shock the first event in the sequence ruptured the segment of the peru chile trench between 37 03 s and 38 74 s whereas the great 1960 chilean main shock ruptured the adjoining segment to the south the great 1960 chilean main shock initiated within the rupture area of the first event and terminated near the intersection of the chile ridge with the peru chile trench 46 5 s

accelerator radiocarbon dating at the molecular level molecular level 14c dating is the isolation of specific classes of molecules for their 14c dating by accelerator mass spectrometry ams complex matrices such as fossil bone are difficult to date due to their extreme chemical heterogeneity by isolating individual amino acids contaminants humates are removed and crystalline amino acids result bones with 0 1 0 2 n and collagenous compositions can be dated accurately because structural collagen is present contaminants are removable with xad resin bones with 0 1 n and non collagenous compositions yield dates hundreds to thousands of years too young because most of the preserved organic matter is exogenous accelerator 14c dates on collagenous and non collagenous bones are not comparable due to intrinsic dating inaccuracies ams 14c dating of amino acids demonstrated that 1 post 10 800 year ages for north american megafauna are due to sample contamination not holocene ages on extinct fauna 2 a clovis age 10 900 years was established for a human fossil from the anzick site montana 3 holocene ages cannot be established absolutely for many north american human fossils because the bones were non collagenous 4 accurate ages are attainable on vertebrate fossils as small as passerine birds from pacific island localities 5 well preserved bones are datable without their destruction by extracting protein with water at high temperatures and 6 stratigraphic anomalies to 45 000 years in european upper paleolithic rock shelters are recognizable by dating bone directly

transient fault slip in guerrero southern mexico the guerrero region of southern mexico has ac cumulated more than 5 m of relative plate motion since the last major earthquake in early 1998 a continuous gps site in guerrero recorded a transient displacement modeling indicates that anomalous fault slip propagated from east to west along strike of the subduction megathrust campaign gps and leveling data corroborate the model the moment release was equivalent to an mw 6 5 earthquake no m 5 earthquakes accompanied the event indicating the frictional regime is velocity strengthening at the location of slip

geomagnetic field control of 14c production over the last 80 ky implications for the radiocarbon time scale we have used a recent estimate of the geomagnetic dipole field strength over the last 80 ky to examine the extent to which changes in geomagnetic field intensity have affected the radiocarbon time scale the magnetic record was converted into a 14c production signal which was then used to produce a synthetic atmospheric 14c record using a two box model for the carbon cycle this calibration suggests that the geomagnetic field has been the main factor governing the production of cosmogenic 14c atoms over the period of time considered and that 14c changes due to other causes such as climatic changes have been of lesser importance the results indicate that the radiocarbon ages are 2 to 3 ky younger than true age in the interval 18 40 ky b p in good agreement with recent u th and 14c age comparisons moreover the results predict that a negligible difference between true and 14c ages should be observed around 45 50 ky

possible shell beads from the middle stone age layers of sibudu cave south africa recent excavations at sibudu cave kwazulu natal south africa uncovered an iron age horizon below which is a complex 3 m thick middle stone age sequence with post howiesons poort howiesons poort still bay and pre still bay layers available osl ages indicate that the howiesons poort occupation is older than 60 ky and the still bay older than 70 ky here we present the archaeological context and the taphonomic analysis of six afrolittorina africana three of which bear perforations from the still bay and howiesons poort layers of this site the single specimen from the latter cultural horizon comes from the lowermost layer attributed to this technocomplex this and the depositional context of this layer suggest that this shell derives as do the other five from the still bay occupation layers taphonomic analysis of the archaeological specimens based on present day afrolittorina africana biocoenoses microscopic examination morphometry experimental perforation of modern shells and a review of the natural agents that may accumulate marine shells at inland sites indicate probable human involvement in the collection transport modification and abandonment of afrolittorina africana in sibudu if confirmed by future discoveries these shells would corroborate the use of personal ornaments already attested at blombos cave western cape province by still bay populations the apparent absence of ornaments at howiesons poort sites raises the question of the mechanisms that have led to cultural modernity since it seems to contradict the scenario according to which cultural innovations recorded at middle stone age sites reflect a process of continuous accretion and elaboration interpreted as the behavioural corollary of the emergence of anatomically modern humans

human occupation of northwest africa a review of middle palaeolithic to epipalaeolithic sites in morocco abstract this paper provides a summary of all available numerical ages from contexts of the moroccan middle palaeolithic to epipalaeolithic and reviews some of the most important sites particular attention is paid to the so called aterian albeit those so labeled assemblages fail to show any geographical and chronological pattern for this reason this phenomenon should not be considered a distinct culture or techno complex and is referred to hereinafter as middle palaeolithic of aterian type whereas anatomical modern humans amh are present in northwest africa from about 160 ka onwards according to current research some middle palaeolithic inventories are more than 200 ka this confirms that for this period it is impossible to link human forms with artifact material perforated shell beads with traces of ochre documented from 80 ka onwards certainly suggest changes in human behavior the transition from middle to upper palaeolithic here termed early upper palaeolithic at between 30 and 20 ka remains the most enigmatic era however the still scarce data from this period requires careful and fundamental revision in the frame of any future research by integrating environmental data in reconstruction of population dynamics clear correlations become obvious high resolution data are lacking before 20 ka and at some sites this period is characterized by the occurrence of sterile layers between middle palaeolithic deposits possibly indicative of shifts in human population after heinrich event 1 there is an enormous increase of data due to the prominent late iberomaurusian deposits that contrast strongly from the foregoing accumulations in terms of sedimentological features fauna and artifact composition the younger dryas shows a remarkable decline of data marking the end of the palaeolithic environmental improvements in the holocene are associated with an extensive epipalaeolithic occupation

fault interactions and subduction tectonics a re examination of the weber new zealand earthquake sequence of 1990 summary two moderate magnitude mw 6 2 and 6 4 earthquakes in the hikurangi subduction margin north island new zealand occurred 3 months apart in 1990 the epicentres are nearly coincident but the first weber 1 primarily normal faulting occurred within the subducting pacific plate depth about 28 km and the second weber 2 a mix of thrusting and right lateral motion occurred within the overlying australian plate depth about 13 km the plate interface in between the plate interface is interpreted to be locked trenchward se from about the position of these events with a transition to aseismic slip further down dip to the nw several stress interaction questions are examined first to see whether weber 1 triggered weber 2 a range of possible mainshock parameters are used to calculate induced changes in the static coulomb failure stress cfs in most cases the results are consistent with triggering secondly previous work showed that the rate of aftershock occurrence for weber 1 decreased markedly about 35 days before weber 2 recovering afterwards to see whether aseismic pre slip on the weber 2 fault as predicted by rate and state friction could be the cause of the decrease the same fault parameters have been used in reverse the results are ambiguous some fault parameters giving results consistent with the hypothesis and others not the amount of pre slip required for significant inhibition however is about equal to that in the mainshock and distributed over the entire fault plane thirdly observations of episodic aseismic slip down dip from locked sections of other plate interfaces are becoming more common could such slip have triggered both weber events the induced changes in cfs for such slip are uniformly positive on the weber 1 fault plane and mostly positive on the weber 2 fault plane so the answer is yes although there is no independent evidence for aseismic slip prior to the weber sequence this case shows that such slip may trigger events on other nearby faults besides loading the locked section of the plate interface static stress triggering considerations are thus likely to be important in subduction environments

stress redistribution and slow earthquakes abstract earthquakes are usually assumed to result when the gradual stress buildup in a region eventually exceeds some initial local strength there are observations which suggest that a number of mechanisms must have a significant role in stress redistribution in active earthquake regions the stress build up could be non linear in time there is evidence that this is so in the case of some major earthquakes one mechanism that might explain non linear strain buildup is a slow earthquake this is similar to a normal earthquake except that the rupture and slip velocities are very low so that negligible energy is radiated in the normally observed seismic frequency band the slow earthquakes studied here have been recorded by a network of sacks evertson borehole strainmeters installed along the seismically active pacific coast of honshu japan larger slow events may have slow foreshocks and aftershocks in a manner similar to that for normal earthquakes the aftershocks appear to have lower stress drops than the foreshocks the static field changes associated with the izu oshima earthquake m 7 of january 1978 were sufficiently large that they were clearly recorded by the nearest three strainmeters interpretation of the records indicate that this earthquake was in essence a normal quake followed by a slow event of similar moment this interpretation is corroborated by reports of ground vibration and faulting on the izu peninsula

the last occurrence of megaceroides algericus lyddekker 1890 mammalia cervidae during the middle holocene in the cave of bizmoune morocco essaouira region during the course of archaeological test excavations carried out in 2007 in the cave of bizmoune essaouira region morocco seven archaeological layers yielding pleistocene and holocene artefacts and faunal remains were identified in the layers c4 c3 and c2 respectively from the oldest to the most recent terrestrial helicidae mollusk shells helix aspersa were dated by 14c these layers also contained many fragments of eggshell belonging to struthio cf camelus associated with mammal remains such as oryctolagus lepus gazella sp sus scrofa ammotragus lervia alcelaphus buselaphus equus sp phacochoerus aethiopicus and an undetermined caprini among these remains an incomplete mandible of megaceroides algericus lydekker 1890 with m1 and m2 was found in layer c3 the 6641 to 6009 cal bp time range attributed to this layer has provided the most recent date known so far for m algericus in this study we review and contextualize the findings of this particular species both in time and space and discuss its systematic position we describe the morphology of the typical pachyostosic mandibular bone with the teeth and compare the dimensions with existing data the assumption of the combined development on the one hand of the pachyostosic phenomenon and on the other hand of the body weight fluctuations and growth of antlers for cervids strongly affected by seasonality is not supported in order to understand the origin and the extinction of m algericus we examined the ams radiocarbon dates available in the literature and calibrated them with rendatemodel software comparisons are then made with sea surface temperatures e g gisp2 18o eustasy and related environmental changes throughout the time span of this species based on these data a possible migration route by the strait of gibraltar connected with with eustatic rises in sea level rises are discussed the speciation extinction processes for m algericus and their correlations with climatic shifts on a long time scale in north africa e g heinrich events 8200 cal bp event are also considered finally this new discovery in bizmoune cave clearly shows that m algericus lasted until the very end of the epipaleolithic around 6000 cal bp middle holocene whereas this species was formerly not believed to have survived until the early epipaleolithic around 8000 cal bp