late quaternary geological history of the dead sea area israel abstract a 34 5 m borehole which was drilled near the dead sea coast altitude 394 m in the southern part of the fan delta of wadi zeelim reveals the geological history of that area from the latest pleistocene to present the depositional time frame is based on six 14c dates and two u th dates an erosional or nondepositional period is implied by the hiatus between 21 100 yr b p u th age depth 33 m and 11 315 yr b p 14c age depth 32 m a subsequent arid phase is recorded by a 6 5 m thick layer of halite based on 14c dates this phase relates to the abrupt younger dryas cold period reported in temperate to polar regions the fragility of the environment in this region is indicated by the fact that the region experienced such a severe short aridification phase less than 1000 yr evidence of which is found widely in the desert fringes of the middle east and north africa the aragonite found in most of the holocene section indicates that the well site was covered by the lake for most of the holocene exceptions are the intervals at 0 3 and 10 14 m depths which represent low stands of the lake

humid to arid to subhumid vegetation shift on pilliga sandstone ulungra springs new south wales abstract the pilliga sandstone region of the northwest slope of new south wales has a natural vegetation cover of sclerophyllous relatively closed to open forests with a largely heathy understorey and a warm subhumid and continental climate pollen analysis of spring fed deposits gives a vegetation history extending from at least 30 000 yr b p to the late holocene tree pollen became scarce after about 25 000 yr b p and an assemblage dominated by chenopodiaceae liguliflorae tubuliflorae and probably poaceae developed no similar assemblage is known from present pollen rain studies carried out in australia however it clearly represents a treeless open shrub steppe formation and therefore an arid or semiarid environment the site thus provides evidence of an eastward late pleistocene extension of the arid zone in australia and is the first full glacial vegetation record between 20 and 35 latitude in australia the present vegetation cover did not become reestablished until the beginning of the holocene which raises questions about the form in which pilliga sandstone vegetation survived full glacial conditions

cosmogenic nuclide chronology of millennial scale glacial advances during o isotope stage 2 in patagonia the terrestrial glacial record reflects past snowline variability and atmospheric temperature changes when combined with secure chronologies these data can be used to test models of ice age climate we present new in situ cosmogenic 1 0 be 2 6 al and 3 he exposure ages supported by limiting 4 0 ar 3 9 ar and 1 4 c ages for seven of the youngest moraines east of lago buenos aires argentina 46 5 s that were deposited by a large outlet glacier of the patagonian ice cap following a major glaciation that deposited extensive moraines prior to 109 ka paired 1 0 be 2 6 al ages indicate that the next youngest complex of moraines was deposited from 23 0 1 2 to 15 6 1 1 ka 1 during the last glaciation ice was at its maximum extent prior to 22 ka and at least five moraines were deposited in less than 10 k y these data are in good agreement with three 1 4 c ages of ca 16 ka from varved sediment banked on top of the youngest of these five moraines and limiting 3 he ages which range from ca 33 to 19 ka the most extensive ice marginal deposits preserved within the last 109 k y were formed during marine oxygen isotope stage 2 no moraines dating to stage 4 were found for stage 2 the distribution of ages at lago buenos aires is similar to cosmogenic nuclide based glacial chronologies from western north america in fact the structure of the last mid latitude south american ice age specifically the overall timing a maximum ice extent prior to 22 ka and deglaciation after 16 ka is indistinguishable from that of the last major glaciation in the northern hemisphere despite a maximum in southern hemisphere insolation during this period the similar mid latitude glacial history in both hemispheres implies that a global climate forcing mechanism such as atmospheric cooling as opposed to oceanic redistribution of heat synchronizes the ice age climate on orbital time scales

revisiting an arid lgm using fluvial archives a luminescence chronology for palaeochannels of the murrumbidgee river south eastern australia the riverine plain in south eastern australia contains numerous palaeochannels that are much larger than the present rivers and provide evidence about past hydrological conditions previous research suggested optima in fluvial activity both before and after the peak of the last glacial maximum lgm 21 3 ka and in some cases throughout the lgm in this study we revisit palaeochannel remnants of the gum creek and yanco palaeochannel systems along the murrumbidgee river which drains the high elevation catchments of the australian alps in south eastern australia we date fluvial and aeolian sediments using single grain optically stimulated luminescence osl and apply thermoluminescence tl dating to a subset of samples we compare the osl ages to new and previously published tl ages and investigate reasons for age discrepancies between these methods possible effects of partial bleaching and other factors that may affect luminescence ages we propose a new osl based chronology for the gum creek and yanco palaeochannel systems and assign periods of enhanced fluvial activity for the tombullen and yanco phases to 41 29 and 29 18 ka respectively importantly we infer that conditions of increased sediment and water discharge persisted for the murrumbidgee river at the time of the lgm

late quaternary climates of the australian arid zone a review abstract aridity in australia has generally been associated with glacial intervals of the last few glacial cycles the causes and nature of aridity varied from north to south over the continent in northern and central australia reduced monsoon rain in global cold stages caused lakes and rivers to dry vegetation to become more sparse sand dunes to become active and dust advection to increase while the monsoon is correlated with warmer global temperatures and high sea levels overall the exact timing of the greatest development of the monsoon in stage 5 remains uncertain in southeastern australia the proxy records give a less clear picture while vegetation seems to have been more sparse in cold stages and sand dune activity and dust flux consequently greater records of runoff in rivers and lakes have mixed or opposite behaviour to northern or central australia the nature of aridity in southeastern australia is not analogous to conditions anywhere on the continent today greatly reduced temperatures over the central and southern interior greater influence of snow and periglaciation on runoff high groundwater tables lower rainfall and reduced atmospheric carbon dioxide levels may all have contributed to and interacted to produce the reconstructed picture of a cold sparsely vegetated arid landscape with large rivers and perennial lakes the largest changes in circulation patterns over the glacial cycle probably occurred in the location and or intensity of summer tropical convergence in northern australia over southern australia changes to the temperature and humidity of the westerly circulation have been more significant than the small fluctuations in latitude of the sub tropical high pressure ridge

the association of micro earthquake clusters with mapped faults in the dead sea basin about 1100 micro earthquakes that occurred along the dead sea basin during the past 25 years express ongoing seismic activity along mostly obscured fault segments we apply seismological and statistical methods in order to associate seismic activity with geological and geophysical data and to locate and characterize active fault segments in the basin three regional 1 d velocity models and the double difference method were used for the relocation of seismic events geostatistical analysis shows that in first order the micro earthquakes reflect faulting along segments of the main longitudinal fault while seismic quiescence along historically active zones indicates locked segments and stress concentration based on waveform similarity spatial and temporal proximity we define earthquake clusters that comprise about 30 of the relocated seismicity and two thirds of the total seismic moment about 80 of the clusters are associated with n s trending faults in two cases the clusters indicate a migration of the seismicity in time and space one of which preceded the largest earthquake in our catalog m5 2 in addition to the associated longitudinal activity several clusters appear to represent faulting in east west orientation which is interpreted here as a secondary fault system

climatic records over the past 30 ka from temperate australia a synthesis from the oz intimate workgroup temperate australia sits between the heat engine of the tropics and the cold southern ocean encompassing a range of rainfall regimes and falling under the influence of different climatic drivers despite this heterogeneity broad scale trends in climatic and environmental change are evident over the past 30 ka during the early glacial period 30 22 ka and the last glacial maximum 22 18 ka climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important murray darling basin the temperate region at this time appears to be dominated by expanded sea ice in the southern ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast including tasmania and southwest australian coasts the deglacial period 18 12 ka was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records while there is some evidence for climatic reversals e g the antarctic cold reversal in high resolution marine sediment cores through this period the high spatial density of holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after 12 ka presumably in response to increasing temperature while hydrological records reveal spatially heterogeneous hydro climatic trends patterns after 6 ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the el nino southern oscillation

from source to sink a new perspective on the past dynamics of the murray canyon group from benthic foraminiferal communities abstract we present fossil benthic foraminiferal assemblage data from marine sediment core ss02 06 gc2 located in the abyssal plain of the murray canyon group offshore south australia the sedimentological characteristics indicate the presence of turbidite deposits showing classical bouma like sequences dated between 40 and 12 cal ka bp these results confirm the previous interpretation of the observed large deep water holes in the abyssal area where the core was sampled as being gouged by surges of high energy turbidity currents the presence of good indicator taxa and unique assemblages occupying specific bathymetric depths allows the determination of the source origin of the sediments making the turbidites three distinct faunal groups are found 1 mostly shelf species 2 mostly bathyal species and 3 mostly abyssal species in the sediment core these groups present a quasi systematic succession with nearly all bouma like sequences starting with the dominance of bathyal species in the coarse grained base followed by the dominance of shallow species in the silty part and finally with abyssal species in the clays to explain such phenomena turbidites triggered by mixed hyperpycnal hypopycnal flow processes and turbidity currents during periods of river floods are considered for the first time within the murray canyon group they are mostly related to periods of increased fluvial discharges during wet phases in the murray darling basin

use of soils and colluvial deposits in analyzing tectonic events the southern arava rift israel abstract buried soils in colluvium units developed on downthrown fault blocks have been presumed to form during periods of tectonic quiescence this assumes however that all colluvial units on a fault scarp are tectonically induced particularly for a multiple event fault scarp to test this hypothesis we compared the colluvial stratigraphy and pattern of soil development on two non tectonic scarps terrace risers and a nearby multiple event fault scarp on the same alluvial fan surface both slopes developed under extremely and climatic conditions the colluvial stratigraphy and soil catenary relationship developed on terrace risers were found to be substantially different from those on the multiple event fault scarp the fault scarp colluvium contained several colluvial units separated by soils whereas only two colluvial units without buried soils were found on the terrace risers the colluvial units on the fault scarp were triangular in shape while those on the terrace riser were concave and overlapped up the slope cumulic soils indicating a continuous and low rate of deposition during pedogenesis were formed along the terrace riser in contrast buried soils indicating episodic deposition occurred on the downthrown block of the multiple event fault scarp accordingly the colluvial stratigraphy developed on the fault scarp can be viewed as a record of distinct tectonic events with no climatically controlled deposition the data indicate that soils and sedimentary stratigraphy can serve as useful indicators to distinguish terrace risers and single event fault scarps from multiple event fault scarps these indicators can be helpful in distinguishing phases of tectonic activity and in evaluating recurrence intervals on a multiple fault scarp

magnitudes and locations of the 1811 1812 new madrid missouri and the 1886 charleston south carolina earthquakes we estimate locations and moment magnitudes m and their uncertainties for the three largest events in the 1811 1812 sequence near new madrid missouri and for the 1 september 1886 event near charleston south carolina the intensity magnitude m i our preferred estimate of m is 7 6 for the 16 december 1811 event that occurred in the new madrid seismic zone nmsz on the bootheel lineament or on the blytheville seismic zone m i is 7 5 for the 23 january 1812 event for a location on the new madrid north zone of the nmsz and 7 8 for the 7 february 1812 event that occurred on the reelfoot blind thrust of the nmsz our preferred locations for these events are located on those nmsz segments preferred by johnston and schweig 1996 our estimates of m are 0 1 0 4 m units less than those of johnston 1996b and 0 3 0 5 m units greater than those of hough et al 2000 m i is 6 9 for the 1 september 1886 event for a location at the summerville middleton place cluster of recent small earthquakes located about 30 km northwest of charleston

gps measurements of current crustal movements along the dead sea fault 1 a network of 11 continuous gps stations was constructed in israel between 1996 and 2001 to monitor current crustal movements across the dead sea fault dsf analysis of the gps measurements with respect to the itrf2000 reference frame yields time series of daily site positions containing both secular and seasonal variations horizontal secular variations station velocities are evaluated with respect to the main tectonic element in the region the dsf we use six velocity vectors west of the dsf to define the itrf2000 pole of the sinai sub plate and rotate the velocity field for all stations into the sinai reference frame srf the velocity vectors reveal that 1 relative station movements are less than 4 mm yr 2 the nine stations located west of the dsf show no statistically significant motion with respect to the srf and 3 the two stations located in the golan heights katz and elro and a station in damascus syria udmc show 1 7 2 8 mm yr northward motion with respect to sinai indicating a left lateral motion along the dsf using locked fault models we estimate the current slip rate across the dsf as 3 3 0 4 mm yr if we exclude the northern sites elro and udmc which are located adjacent to the compressional jog of mount hermon our estimate increases to 3 7 0 4 mm yr the calculated itrf2000 sinai eurasia and nubia poles and a published pole for arabia allow us to calculate the current relative plate motion of sinai arabia and sinai nubia

estimation of high resolution sediment concentration profiles in bottom boundary layer using pulse coherent acoustic doppler current profilers abstract the capability of two acoustic profilers sontek s 1 5 mhz pulse coherent acoustic doppler profiler pc adp and rdi s 600 khz acoustic doppler current profiler adcp with pulse coherent mode was evaluated for estimating high resolution suspended sediment concentration ssc profiles in bottom boundary layer in the laboratory measurements with a pc adp two types of sediments were tested to study acoustic responses to grain size a natural sediment sample from clay bank a mixture of clay and very fine sand showed a good linear relationship between range corrected volume scattering s v and backscattered strength e until ssc increased up to about 10 g l 1 in contrast a commercially available kaolinite exhibited earlier signal saturation and non unified linear regressions between s v and e most likely because the particle size is much smaller than the transmitted acoustic wavelength using a pulse coherent adcp the field measurement results from mobile bay alabama showed that the acoustically derived ssc profiles were well matched with the optically derived outcomes although slight discrepancies were noted the overestimation of acoustically derived ssc near the bed may be related to the side lobe interference near the bed and the enhanced acoustic sensitivity by coarser particles and denser aggregates eroded from the bed mean absolute error of acoustic estimates was within 4 1 7 3 of the optically derived ssc range which is attributable to the different acoustic and optical scattering responses to given sediment size spectra despite some error sources in acoustic inversion the results from laboratory and field experiments suggest that the pulse coherent acoustic profiler is able to reveal the evolution of in situ near bed ssc profiles with high vertical and temporal resolutions

internal structure of the dead sea leaky transform rift in relation to plate kinematics abstract the structures along the dead sea transform rift are related to the motions of the sinai and arabia plates which border it and to the irregularities of their boundaries the total slip was 105 km left lateral but the present structures were formed mainly during the last 40 km of slip which probably occurred in the plio pleistocene along the southern half of the transform the strike slip motion takes place on en echelon faults this produces rhomb shaped grabens or pull aparts which are sometimes composite and in which there is local crustal separation thus much of the transform is leaky these structures occur in a morpho tectonic rift valley delimited by normal faults which express a small component of transverse extension along a few segments the shape of the transform is such that lateral motion produces local transverse compression the geometric relations of the structures along the transform define an eulerian pole of relative plate motions at 32 8 n 22 6 e 0 5 the older motion was somewhat different and is described by a pole located about 5 west of the above then the component of transverse extension and crustal separation was much smaller than now while local transverse compression was more important the northern half of the dead sea transform has an irregular shape and the bordering plates did not remain rigid as lateral motion continued here transverse compression is often important

palaeohydrology of lowland rivers in the murray darling basin australia abstract this study derives a new function describing the relationship of channel bankfull discharge qbf to channel width in modern rivers of the murray darling basin mdb of southeastern australia and applies this to dated palaeochannels of seven rivers to quantify late quaternary discharge history in this important basin all rivers show high mis3 and mis2 qbf declining in the holocene the qbf of modern mdb rivers is correlated with total catchment precipitation but comparison with palaeochannel qbf estimates shows that while enhanced runoff efficiency is necessary to account for much larger late pleistocene palaeochannels either lower or higher precipitation rates could have prevailed a strong association between relative palaeo qbf enhancement and temperature suggests a temperature mediated mechanism controlling river discharge such as the fraction of precipitation stored as snow and thawing in spring the enhancement of orographic rainfall or co2 feedbacks with vegetation cover significantly enhanced mis3 qbf requires an additional mechanism such as increased rainfall these findings are consistent with others that increased moisture availability was associated with past colder climates although this was not necessarily the result of enhanced precipitation

catastrophic arid episodes in the eastern mediterranean linked with the north atlantic heinrich events the response of continental climate to the well documented climate oscillations during the last glacial period has been a subject of intense interest yet much less is known about the influence on regional continental climates than in the marine or polar realms of earth the detailed lake level history of the closed lake lisan paleo dead sea in the middle east has been reconstructed from shoreline indications and high resolution u th and 1 4 c chronologies thus providing data on the response of the lake s catchment area to the climate changes during the corresponding period we present a correlation between the newly developed lake lisan level curve for the past 55 k y and the north atlantic heinrich events the correlation indicates a closely connected climate response between these north atlantic events and the hydrologic conditions that prevailed in the eastern mediterranean our findings show that although the generally cooler conditions that prevailed during the last glaciation favored high levels of the lake catastrophic events in the north atlantic which are associated with maximum cooling have been responsible for droughts in the eastern mediterranean we infer that cold water input to the mediterranean originating in the collapse of the north atlantic deep water circulation caused the reduction of evaporation and less precipitation in the eastern mediterranean

crustal deformation along the dead sea transform and the carmel fault inferred from 12 years of gps measurements received 20 february 2012 revised 27 june 2012 accepted 30 june 2012 published 17 august 2012 1 large scale crustal deformation in the levant is mainly related to the dst and the cfs the former is an active left lateral transform bounding the arabian plate and the sinai sub plate and the latter branches out of the former and separates the sinai sub plate into two tectonic domains in this study we obtain the velocities of 33 permanent gps stations and 145 survey stations that were surveyed in three campaigns between 1996 and 2008 we use a simple 1 d elastic dislocation model to infer the slip rate and locking depth along various segments of the dst we infer a 3 1 4 5 mm yr slip rate and a 7 8 16 5 km locking depth along the dst north of the cfs and a slip rate of 4 6 5 9 mm yr and locking depth of 11 8 24 km along the jericho valley south of the cfs further south along the arava valley we obtain a slip rate of 4 7 5 4 mm yr and a locking depth of 12 1 23 km we identify an oblique motion along the carmel fault with 0 7 mm yr left lateral and 0 6 mm yr extension rates resulting in n s extension across the carmel fault this result together with the decrease in dst slip velocity from the jericho valley to the segment north of the cfs confirms previous suggestions according to which part of the slip between arabia and sinai is being transferred from the dst to the cfs

formation of sequential basins along a strike slip fault geophysical observations from the dead sea basin abstract the dead sea basin is often cited as one of the classic examples for the evolution of pull apart basins along strike slip faults despite its significance the internal structure of the northern dead sea basin has never been addressed conclusively in order to produce the first comprehensive high resolution analysis of this area all available seismic data from the northern dead sea lake lower jordan valley land were combined results show that the northern dead sea basin is comprised of a system of tectonically controlled sub basins delimited by the converging western and eastern boundary faults of the dead sea fault valley these sub basins grow shallower and smaller to the north and are separated by structural saddles marking the location of active transverse faults the sedimentary fill within the sub basins was found to be relatively thicker than previously interpreted as a result of the findings of this study the classic model for the development of pull aparts based on the dead sea is revised the new comprehensive compilation of data produced here for the first time was used to improve upon existing conceptual models and may advance the understanding of similar basinal systems elsewhere

climate variability over the last 35 000 years recorded in marine and terrestrial archives in the australian region an oz intimate compilation abstract the australian region spans some 60 of latitude and 50 of longitude and displays considerable regional climate variability both today and during the late quaternary a synthesis of marine and terrestrial climate records combining findings from the southern ocean temperate tropical and arid zones identifies a complex response of climate proxies to a background of changing boundary conditions over the last 35 000 years climate drivers include the seasonal timing of insolation greenhouse gas content of the atmosphere sea level rise and ocean and atmospheric circulation changes our compilation finds few climatic events that could be used to construct a climate event stratigraphy for the entire region limiting the usefulness of this approach instead we have taken a spatial approach looking to discern the patterns of change across the continent the data identify the clearest and most synchronous climatic response at the time of the last glacial maximum lgm 21 3 ka with unambiguous cooling recorded in the ocean and evidence of glaciation in the highlands of tropical new guinea southeast australia and tasmania many terrestrial records suggest drier conditions but with the timing of inferred snowmelt and changes to the rainfall runoff relationships driving higher river discharge at the lgm in contrast the deglaciation is a time of considerable south east to north west variation across the region warming was underway in all regions by 17 ka post glacial sea level rise and its associated regional impacts have played an important role in determining the magnitude and timing of climate response in the north west of the continent in contrast to the southern latitudes no evidence for cooling during the younger dryas chronozone is evident in the region but the antarctic cold reversal clearly occurs south of australia the holocene period is a time of considerable climate variability associated with an intense monsoon in the tropics early in the holocene giving way to a weakened monsoon and an increasingly el nino dominated enso to the present the influence of enso is evident throughout the southeast of australia but not the southwest this climate history provides a template from which to assess the regionality of climate events across australia and make comparisons beyond our region

salt diapirs in the dead sea basin and their relationship to quaternary extensional tectonics abstract regional extension of a brittle overburden and underlying salt causes differential loading that is thought to initiate the rise of reactive diapirs below and through regions of thin overburden we present a modern example of a large salt diapir in the dead sea pull apart basin the lisan diapir which we believe was formed during the quaternary due to basin transtension and subsidence using newly released seismic data that are correlated to several deep wells we determine the size of the diapir to be 13 10 km its maximum depth 7 2 km and its roof 125 m below the surface from seismic stratigraphy we infer that the diapir started rising during the early to middle pleistocene as this section of the basin underwent rapid subsidence and significant extension of the overburden during the middle to late pleistocene the diapir pierced through the extensionally thinned overburden as indicated by rim synclines which attest to rapid salt withdrawal from the surrounding regions slight positive topography above the diapir and shallow folded horizons indicate that it is still rising intermittently the smaller sedom diapir exposed along the western bounding fault of the basin is presently rising and forms a 200 m high ridge its initiation is explained by localized e w extension due monoclinal draping over the edge of a rapidly subsiding basin during the early to middle pleistocene and its continued rise by lateral squeezing due to continued rotation of the amazyahu diagonal fault

prehistoric earthquake deformations near masada dead sea graben earthquake inducedfluidizations and suspensions of lake sediments associated with syndepositionalfaults formapaleoseismicrecordinthedeadseagraben theassociation offluidized beds with surface faulting supports the recognition of mixed layers as reliable earthquake indicators and provides a tool for the study of very long term 70 kar seismicity along the dead sea transform the faults compose a fault zone that offsets laminated sediments of the late pleistocene lake lisan they exhibit displacements of as much as 2 m layers of massive mixtures of laminated fragments are interpreted as disturbed beds each formed by an earthquake the undisturbed laminated layers between these mixed layers represent the interseismic interval a typical vertical slip of about 0 5 m per event is separated by several hundred years of quiescence the fault zone lies within the dead sea graben 2 km east of masada where archaeology and historical accounts indicate repeated strong earthquake damage the distribution of strikes in the fault zone resembles that of the faults exposed in and around the graben including the seismogenic ones the excellent exposures over hundreds of metres allow an unprecedented temporal and spatial resolution of slip events on faults

evaluation of two conflicting paradigms for cohesive sediment deposition abstract laboratory experiments using steady flows and simulated tidal flows were conducted to evaluate two conflicting paradigms for cohesive sediment transport mutually exclusive vs simultaneous erosion and deposition due to the secondary flow and skewed distribution of bed shear stress b the deposition space is mostly confined to the inner wall of an annular flume the area of deposition or the length of deposition because of the axially symmetrical flow provides an indicator to determine when deposition at the sediment water interface starts the direct observation of deposition stemming from the inner corner suggests that a critical shear stress for deposition cd 0 03 0 06 pa does exist changes in deposit length and depth averaged suspended sediment concentration ssc under simulated tidal cycles demonstrate that deposition can happen only in tidal decelerating phases when local b is less than cd the exclusive paradigm incorporated with the correct erosion threshold ce profile and erosion behavior could explain changes in laboratory and field observed depth averaged ssc under all tidal regimes

current plate motion across the dead sea fault from three years of continuous gps monitoring 1 the dead sea fault dsf is a transform plate boundary between the arabian plate and the sinai sub plate the rate of displacement across the fault has been estimated as 1 10 mm yr in this study we present a new estimate of the current displacement across the dsf which is based on three years of continuous global positioning system measurements july 1996 to july 1999 our analysis of these data shows that relative northward velocity which is the fault parallel component on the baseline between tel aviv and katzerin golan heights and katzerin and elat is 1 4 0 3 mm yr and 1 0 0 5 mm yr respectively assuming a colored noise white noise plus flicker noise model for the daily position estimates by using a simple locked fault model we estimate that during the three year observation period the relative plate motion across the dsf was 2 6 1 1 mm yr

late holocene activity of the dead sea transform revealed in 3d palaeoseismic trenches on the jordan gorge segment three dimensional excavations of buried stream channels that have been displaced by the jordan fault the primary strand of the dead sea fault zone in northern israel demonstrate that late holocene slip has been primarily strike slip at a minimum rate of 3 mm yr the palaeoseismic study was carried out in the bet zayda valley the delta of the jordan river at the north shore of the sea of galilee the site was chosen where a north striking scarp with up to 1 m vertical expression crosses the flat valley one group of trench excavations was located where a small stream crosses the scarp the active stream which is incised into the scarp is not offset by the fault however we found two palaeo channels about 2 m below the surface offset sinistrally 2 7f0 2 m by the fault and two younger nested channels offset 0 5f0 05 m based on radiocarbon dates we attribute the last 0 5 m rupture to the earthquake of october 30 1759 the older offset of 2 2 m most probably occurred in the earthquakes of may 20 1202 these two events correlate with the findings at ateret about 12 km north of bet zayda where the 1202 earthquake produced 1 6 m of lateral displacement in e w striking defence walls of a crusader castle and an ottoman mosque was offset 0 5 m in the earthquake of 1759 in the second group of trenches some 60 m farther south we found another offset channel its northern margin is displaced 15 m sinistrally whereas the southern margin shows only 9 m of sinistral offset the dip slip component is 1 2 m west side down the different amounts of margin offset can be explained by erosion of the southern margin during the first 6 m of displacement additional slip of 9 m accrued after the stream had been abandoned and buried by a 2 mthick lacustrine clay layers radiocarbon dates on organic residue provide the age control which indicates that the 15 m of slip has accrued over the past 5 kyr yielding a short term slip rate of 3 mm yr for the late holocene it is possible that our study

slip rate on the dead sea transform fault in northern araba valley jordan the araba valley lies between the southern tip of the dead sea and the gulf of aqaba this depression blanketed with alluvial and lacustrine deposits is cut along its entire length by the dead sea fault in many places the fault is well defined by scarps and evidence for left lateral strike slip faulting is abundant the slip rate on the fault can be constrained from dated geomorphic features displaced by the fault a large fan at the mouth of wadi dahal has been displaced by about 500 m since the bulk of the fanglomerates were deposited 77 140 kyr ago as dated from cosmogenic isotope analysis 10 be in chert of pebbles collected on the fan surface and from the age of transgressive lacustrine sediments capping the fan holocene alluvial surfaces are also clearly offset by correlation with similar surfaces along the dead sea lake margin we propose a chronology for their emplacement taken together our observations suggest an average slip rate over the late pleistocene of between 2 and 6 mm yr 1 with a preferred value of 4 mm yr 1 this slip rate is shown to be consistent with other constraints on the kinematics of the arabian plate assuming a rotation rate of about 0 396 myr 1 around a pole at 31 1 n 26 7 e relative to africa

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

late quaternary changes in flow regime on the gwydir distributive fluvial system southeastern australia abstract ages for large palaeochannels of the gwydir distributive fluvial system dfs in northern new south wales australia have been determined using single grain optically stimulated luminescence two palaeochannel systems have been found to dominate the here named coocalla 43 34 ka and kamilaroi 19 16 ka which have inferred palaeodischarges 25 100 times the bankfull discharges of nearby channels of the contemporary gwydir system which appears to have been established during the mid holocene this scale differential is very much larger than that reported for other catchments in southeastern australia and reflects both a decline in catchment runoff through the last glacial cycle and the adoption of a distributary pattern sometime after 16 ka actual decline in catchment runoff determined by comparing estimated palaeodischarge with contemporary flows upstream of the dfs where flow is confined to a single channel indicate contemporary discharge to be 0 1 times and 0 25 times that of the coocalla and kamilaroi respectively the chronology presented here shows periods of increased discharge in the gwydir to be more or less coincident with those observed elsewhere in the murray darling basin although no evidence of a gum creek fluvial phase from 35 to 25 ka was found the coocalla and kamilaroi palaeochannel systems broadly conform in age to kerarbury and yanco fluvial phases on the murrumbidgee and murray systems this synchronicity with more southern catchments supports the hypothesis that la nina like conditions were semi permanent for much of the last glacial cycle with moisture derived largely from the western pacific ocean

environmental processes of the ice age land oceans glaciers epilog knowledge of the state of the earth at the last glacial maximum lgm an interval around 21 000 years ago is an important benchmark for understanding the sensitivity of global environmental systems to change much progress in understanding climates of the lgm has occurred in the 20 years since the end of the climap project of the 1970s climate long range investigation mapping and prediction here we review this progress based on presentations and discussion at a rst open science meeting of the epilog project environmental processes of the ice age land oceans glaciers held in delmenhorst germany may 1999 we outline key controversies and document protocols for epilog contributions so that a new synthesis of the lgm earth can emerge as an open project of the world s community of scientists 2001 elsevier science ltd all rights reserved

holocene tectonic deformation along the western margins of the dead sea abstract to assess the young tectonic activity along the western margins of the dead sea and north of the lake faults were studied within sediments which are up to 60 000 years old the western margins of the dead sea are dominated by normal step faults which are exposed up to 2 km east of the morphological escarpment of the basin the rate of subsidence accommodated by these normal faults is estimated to be about 0 85 mm y the distribution of the faults suggests that holocene fault activity was most intense in the northwestern corner of the dead sea north of the lake left lateral slip along the jordan fault produced both local compression and extension small reverse faults and folds exposed along this fault indicate a minimum left lateral slip rate of 0 7 mm y

stress tensor and focal mechanisms along the dead sea fault and related structural elements based on seismological data the dead sea fault is among the largest active strike slip fault of the world this study is focused on the southern part of this fault from the sea of galilee to the gulf of aqaba as monitored mainly by the jordanian and israeli seismic networks the data of arrival times and polarities allowed relocation of earthquakes with a better azimuthal coverage and computation of focal mechanisms this last step has been realized by inverting the polarities to determine a unique stress tensor for the region and the compatible focal mechanisms inversion with different subsets of the data set based on tectonic regionalization has also been performed to evaluate the impact of each cluster of earthquakes on the global solution the population of focal mechanisms is clearly dominated by strike slip events with the notable exception of a cluster of earthquakes south of the dead sea which displays several normal focal mechanisms this last cluster forces 1 to be vertical and 2 to be horizontal a large number of fault planes however are close to the vertical inhibiting the action of the vertical component of the stress tensor and acting like under strike slip stress regime we observed a good agreement between the location of the earthquakes and the active faults based on geological data in addition there is a good agreement between the fault plane solutions and the orientation of the active faults

the nisi fault as a key structure for understanding the active deformation of the nw peloponnese greece abstract the previously unknown nisi fault in nw peloponnese was ruptured during the 2008 movri mountain earthquake attaining a maximum offset of 25 cm the fault is interpreted as a branch of a flower structure above a blind strike slip fault we investigate the nisi fault seismotectonic evolution using morphotectonic analysis in order to determine whether the landscape is affected by tectonic forcing and paleoseismology to determine earthquake recurrence interval and fault slip rates we applied several geomorphic indices such as the asymmetry factor af the stream length gradient index sl the valley floor width to valley height ratio vf the mountain front sinuosity smf the drainage basin shape bs and the hypsometric curve hc in four large drainage basins of the study area the results show that fault related vertical motions and the associated tilting influenced the drainage geometry and the landscape development values of stream gradient indices sl are relatively high close to the fault trace mountain front sinuosity smf mean values along the fault zones range from 1 12 to 1 23 valley floor width to valley height ratios vf mean values along the studied fault range between 0 21 and 2 50 drainage basin shape bs mean values along the fault range from 1 04 to 3 72 lateral fault growth was likely achieved by propagation primarily towards north northwestward the paleoseismic history of the fault investigated by a trench and 14c dating of seven samples indicates two morphogenic earthquakes in the last 1 kyr therefore we suggest that the nisi fault displays a slip rate on the order of 1 mm yr and a recurrence interval ranging between 300 and 600 years from a seismotectonic point of view the fault is classified as high activity rate with abundant but discontinuous geomorphic evidence of its activity other similar faults affecting the western peloponnese can be envisaged with a similar procedure additionally the seismic history and surface expression of the nisi fault resembles other faults of similar length in greece and italy particularly a crucial issue in terms of seismic risk management is that neotectonic analysis has to be envisaged carefully on short in length faults since these faults can be possibly related to strong earthquakes

calibration of the 14c time scale to 40 ka by 234u 230th dating of lake lisan sediments last glacial dead sea a new comparison of 14c dates with 234u 230th ages is presented of aragonites from lake lisan the last glacial dead sea between 20 52 cal ka bp the lisan data are coincident with the coral based 14c calendar age calibration through the continuous portion of the curve to 23 5 cal ka bp and with the additional checkpoints at 30 and 40 cal ka bp the agreement with the corals provides evidence for the accuracy of the u th and 14c ages and indicates that lisan aragonites can potentially be used to generate a nearly continuous record of the atmospheric 14c variations through this crucial time interval the lisan data are compared with other records older than 25 cal ka bp from lake suigetsu japan north atlantic foraminifera south african cave deposits and tufa from spain over some age intervals the records show broad agreement over other intervals they diverge all agree that 14c ages were 2 5 0 5 ka younger than calendar ages between 20 32 cal ka bp for ages 32 cal ka bp the lake suigetsu data indicate small differences between 14c ages and calendar ages of less than 1 5 ka the other records broadly agree that 14c ages are too young by 3 1 ka from 32 39 cal ka bp at 40 cal ka bp the foraminifera show equal 14c and calendar ages while the corals lisan aragonites and the spanish tufa indicate a large age difference of 4 5 ka a recent paleomagnetic study of the lisan formation indicates that the high calendar 14c age difference at 40 cal ka bp may be associated with the laschamp paleomagnetic excursion

active transform fault zone at the fringe of the dead sea basin the evolution of an asymmetric basin at the edge of a pull apart structure is studied using geophysical observations and mechanical modeling a new seismic analysis of the northern edge of the dead sea basin indicates recent subsidence folding and oblique faulting along the jericho strike slip fault a main segment of the dead sea transform fault the subvertical fault trace crosses the entire sedimentary sequence typically branching in the shallow subsurface the seismic analysis reveals the three dimensional structure of the area as an asymmetrical basin bordered on the east and on the west by long monoclinic folds the thickness of the sedimentary fill varies from 1 4 km near the present lake shores to a few hundreds of meters about 10 km northward the subsidence is partitioned between a vertical component of slip along the jericho fault and the simultaneously active monoclines bordering the basin we present a model and simulations that reconstruct the present basin structure in the uppermost part of the crust and demonstrates the generation of flexures along the basin margins without horizontal shortening we show that the basin asymmetry and the association of folds and fault can be explained as a long term ductile response of the sediments to local subsidence the asymmetry along the basin is a consequence of a later vertical displacement component on a pre existing strike slip fault our analysis points to ongoing northward propagation of the dead sea basin and provides an explanation for the structural asymmetry of the basin margins

active compressional tectonics in the jericho area dead sea rift abstract the results of several seismic reflection surveys in the jericho area north of the dead sea are described and the data are used to analyze the structure of this part of the dead sea rift in particular we describe the structure of the dead sea transform which in this area is a zone of intense deformation rather than a distinct fault plane the transform has a westerly dip away from the rift suggesting that it may have a reverse faulting component associated with the transform are several folds of which the best documented is the kalia monocline immediately north of the dead sea the kalia monocline lies along the transform and appears to be a young structure associated with it indicating that this part of the plate boundary is characterized by local compression the southerly extent of the kalia monocline is not clear presently but the available data suggest that the compressional field also characterize the northwestern part of the dead sea basin the other folds appear north of the kalia monocline and seem to be similar to it they are most probably also the result of recent compression along the transform a number of mechanisms of small earthquakes in this area are computed and several of them show thrusting suggesting that the local compression is still active

implications of the northridge earthquake for strong ground motions from thrust faults the peak accelerations recorded on alluvial sites during the northridge earthquake were about 50 larger than the median value predicted by current empirical attenuation relations at distances less than about 30 km this raises the question of whether the ground motions from the northridge earthquake are anomalous for thrust events or are representative of ground motions expected in future thrust earthquakes since the empirical data base contains few strong motion records close to large thrust earthquakes it is difficult to assess whether the northridge ground motions are anomalous based on recorded data alone for this reason we have used a broadband strong motion simulation procedure to help assess whether the ground motions were anomalous the simulation procedure has been validated against a large body of strong motion data from california earthquakes and so we expect it to produce accurate estimates of ground motions for any given rupture scenario including blind thrust events for which no good precedent existed in the strong motion data base until the occurrence of the northridge earthquake the ground motions from the northridge earthquake and our simulations of these ground motions have a similar pattern of departure from empirical attenuation relations for thrust earthquakes the peak accelerations are at about the 84th percentile level for distances within 20 to 30 km and follow the median level for larger distances this same pattern of departure from empirical attenuation relations was obtained in our simulations of the peak accelerations of an elysian park blind thrust event prior to the occurrence of the northridge earthquake since we are able to model this pattern with broadband simulations and had done so before the northridge earthquake occurred this suggests that the northridge strong motion records are not anomalous and are representative of ground motions close to thrust faults accordingly it seems appropriate to include these recordings in strong motion data sets that are used to develop empirical ground motion attenuation relations for thrust faults and to use this augmented data set as the basis for evaluating the need for modifications in design coefficients in the seismic provisions of building codes

holocene palaeochannels at sisatchanalai north central thailand ages significance and palaeoenvironmental indications radiocarbon dating of sediments infilling palaeochannels in the northern part of the central plain of thailand shows that they probably date from the early to mid holocene the composition of bed material of the palaeochannels and the yom river the modern river confirms that the palaeochannels represent earlier courses of the yom the most recent palaeochannel was abandoned about 1700 years ago when the modern course of the yom was established probably by avulsion during a period of increased runoff and flood activity which has also been identified in northeast thailand bankfull discharges qbf of the palaeochannels are estimated in two ways the hydraulic approach combines a palaeochannel s bankfull cross sectional area and an estimate of the average velocity needed to transport the coarse fraction of the channel s bed material the geomorphological approach relies on published equations relating qbf and channel dimensions when applied to the grain size and dimensional characteristics of the mo

primary carbonates and ca chloride brines as monitors of a paleo hydrological regime in the dead sea basin abstract lakes samra lisan and the dead sea occupied the dead sea basin during the last interglacial 140 75 ka bp last glacial 70 14 ka bp and holocene periods respectively the age of lake lisan and samra was determined by u th dating of primary aragonites comprising parts of the lacustrine sedimentary sequences the lakes have periodically deposited sequences of layered calcitic marls lake samra or laminated primary aragonite lake lisan the deposition of aragonite as the primary carbonate phase reflects the contribution of the incoming freshwater loaded with bi carbonate and high mg ca chloride brine that originated from the subsurface vicinity of the dead sea basin deposition of calcitic marls suggests a minor effect of the brines the ca chloride subsurface brine has been migrating in and out of the wall rocks of the dead sea basin reflecting the regional hydrological conditions during most of the last glacial period and during the late holocene sufficient precipitation above the judea mountains pushed the subsurface ca chloride brines into the lakes causing the deposition of aragonite during the last interglacial period the rain that precipitated above the judea mountains was insufficient to induce brine flow toward lake samra it appears that sporadic floods provided calcium bicarbonate and detritus to produce the samra calcitic marls travertines deposited at the samra lisan boundary indicate the early stage in the resumption of groundwater springs activity that led to the resurgence of ca chloride brine and rise of lake lisan similar variations in the regional rain precipitation and hydrological activity probably characterized the long term geochemical evolution of pleistocene lacustrine water bodies in the dead sea basin enabling the use of the carbonates as paleo hydrological monitors

optical dating in archaeology thirty years in retrospect and grand challenges for the future in 1982 when richard klein first became one of the editors of this journal the luminescence dating community was embarking on a new phase of exploratory research attention was turning from the use of thermoluminescence tl dating to estimate the time of last heating of archaeological objects such as pottery and burnt flint to the tl dating of unheated sediments that had been transported by wind and then deposited on the landscape this revolutionary development enabled the extension of tl dating to sedimentary deposits in a variety of environmental settings and to the multitude of archaeological sites that lack suitably heated artefacts in sediment dating the age of most interest is usually the time elapsed since grains of quartz or feldspar were last exposed to sunlight as the energy of the sun s rays is sufficient to evict electrons from their light sensitive traps these traps are steadily refilled after sediment deposition and the longer the grains remain buried the more tl they will emit when measured in 1985 huntley and colleagues proposed optical dating as a simpler and superior means of stimulating the light sensitive traps in quaternary sediments and this is now the principal luminescence based method of dating geological and archaeological deposits optical dating is an umbrella term for an armada of acronyms the most common in archaeological contexts being osl optically stimulated luminescence tt osl thermally transferred osl irsl infrared stimulated luminescence and pirir post infrared irsl all of these variants are founded on the same basic tenet measurement of a light sensitive signal to determine typically the last time that sediment grains were sun bleached but each approach has its virtues and vices in this paper we review this family of luminescence dating techniques and look back on 30 years of optical dating in archaeology some of the more interesting and important achievements are highlighted including the critical insights gained in the last two decades from osl measurements of individual grains of quartz we also look to the future of optical dating in archaeological contexts efforts to extend the age limits of optical dating to older hominin and archaeological sites will remain a key goal and understanding how archaeological sites of all ages form and evolve over time could be improved greatly by combining micromorphology analysis with optical dating of undisturbed intact sediments the latter poses a series of particularly formidable technical challenges but if the past is any guide to the future then we can expect optical dating to illuminate much more of human history before celebrating its golden jubilee

collapse sinkholes and radar interferometry reveal neotectonics concealed within the dead sea basin 1 the dead sea ds pull apart basin is one of the more seismically active segments of the ds transform plate boundary in the last decade hundreds of collapse sinkholes have been formed along the ds coastlines in israel and jordan causing severe damage to the regional infrastructure the formation of these sinkholes is attributed to the dissolution of a buried salt layer by fresh groundwater due to the drop of the ds and the associated groundwater levels here we show that the sinkhole distribution combined with gradual land subsidence measured by radar interferometry insar track young fault systems suspected as active concealed within the fill of the ds rift this notion is supported by 1 sinkholes clustering along discrete lineaments with a striking trend similarity to that of the exposed rift margin faults 2 prominent discontinuities in seismic reflection profiles offsetting young sediments several kyrs old below sinkhole lines and 3 straight boundaries of gradual subsidence features that coincide with or parallel sinkhole lines combined the sinkhole lineaments and the insar measurements reveal a zigzag pattern of buried faults within the ds rift fill

distribution of holocene sediments and neotectonics in the deep north basin of the dead sea abstract the distribution of holocene sediments and active faults in the central portion of the northern dead sea basin was analyzed from high resolution seismic reflection data the seismic reflection profiles reveal that sediments buried at a shallow depth are flat lying continuous and unfaulted within the central basin floor four prominent subsurface seismic reflectors were identified that based on limited core data represent the contact between rock salt and marl layers isopach and structural maps of recent sediments indicate an asymmetry of active subsidence with thick accumulations located closer to the east margin of the basin sediment thickness increases within a rhomb shaped depression whose long axis is oriented approximately 20 30 counterclockwise to the regional basin bounding faults the morphology and trend of the locus of maximum subsidence suggests tectonic control of the depression however the proximity of the depocenter of recent sediments to the ein gedi diapir and rim depression suggests that local sub basinal subsidence may also be related to movement of rock salt at depth the basinal strata are deformed along the faults that form a bathymetric escarpment along the west east and south margins of the north basin of the dead sea thinning of recent sediments toward the faults indicates syntectonic deposition

a high resolution late quaternary depositional history and chronology for the southern portion of the lake mungo lunette semi arid australia abstract the willandra lakes region sits on the southern margin of australia s arid core and is one of the oldest localities on the continent known to have been occupied by australia s first people the archaeological traces that accumulated in the lake mungo lunette paint a picture of changing land use over the past 50 thousand years ka and some of these are likely to have been responses to changes in palaeoenvironmental conditions this study set out to determine the finest temporal resolution that can be used to study the depositional and palaeoenvironmental history of the lake mungo lunette the investigation focused on the depositional history documented within stratigraphy exposed in an eroding gully in the southern part of the lunette gully 10 a stratigraphic framework was developed using sedimentological and soil micromorphological analysis this framework was then fixed in time by 56 single grain optically stimulated luminescence osl age estimates these data sets were then combined into a bayesian model that indicated three depositional phases 100 ka lu1 65 33 ka lu2 lu3 and from 30 to 16 ka lu4 lu9 with the late pleistocene and holocene samples lu10 11 not being modelled furthermore the redating of thirteen lower and upper mungo osl samples from bowler et al 2003 s study of the southern tip of the lunette yielded younger age estimates for twelve of these bringing them into line with previously published independent age control as well as the ages presented in this study this study provides an approach for future efforts to establish consistency in age estimation and palaeoenvironmental interpretation along the length of the lunette

fault geometry and spatial clustering of microearthquakes along the dead sea jordan rift fault zone abstract earthquakes 1 0 m l 5 3 in the region around the dead sea jordan rift fault zone recorded by the israel scismograph station network issn from 1982 until the beginning of 1989 have been analyzed and interpreted the scismicity pattern clearly reveals activity along three fault zones the dead sea jordan rift fault zone the carmel faraa fault zone and the central sinai negev shear zone microearthquake occurrence tends to cluster in or near tensional features rhomb shaped grabens such as the hula sea of gallilee and dead sea depressions further eight representative focal mechanisms of individual earthquakes or earthquake clusters have been derived the seismicity and focal mechanism solutions near the branching of the carmel faraa and the dead sea jordan rift fault zones suggest a complicated tectonic breakup in this region microearthquakes in the arava may indicate a more complex pattern of active faults than was previously assumed

reevaluation of the lake sediment chronology in the dead sea basin israel based on new 230th u dates the dead sea is surrounded by chemical and detrital sediments that were deposited in its larger precursor lakes lake samra and lake lisan the sedimentary history of these lakes was recon structed by means of 230th234u ages of 30 samples mostly of argonite laminae from 8 columnar sections up to 110 km apart the general validity of the ages was demonstrated by subjecting them to tests of internal isotopic consistency agreement with stratigraphic order and concordance with 14c ages in the south only the part of the samra formation older than 170 000 yr is exposed while the aragonite detritus rhythmites found in the central and northern region are generally younger than 120 000 yr the lisan formation started accumulating about 63 000 yr b p with the clay and aragonite beds in the south central area reflecting a rise in water level to at least 280 m the upper part of the lisan formation the aragonite rich white cliff member started accumulating about 36 000 yr b p the lake probably reached its highest level sometime after this based on the ages of lisan sediments preserved in the southernmost reaches of the basin

the southern hemisphere westerlies in the australasian sector over the last glacial cycle a synthesis abstract the southern hemisphere westerlies in the southwest pacific are known to have waxed and waned numerous times during the last two glacial cycles though even semi continuous histories of the westerlies extend back no more than about 20 000 years we have good evidence for at least three scales of events a westerly maximum occurs at the last glacial maximum there is less conclusive evidence for another westerly maximum in the late holocene and for a minimum at ca 11 ka it is too early to ascribe even a cycle to these data but there are grounds to suggest that milankovitch precessional forcing may underlie the observed pattern there is also a quasi 2600 year cycle present in antarctic ice cores that appears to correlate to variation in westerly flow there is strong centennial scale variability in historical times the little ice age lia ca 1400 1850 was associated with a poleward shift in the circumpolar trough in the southern ocean strengthened westerly circulation over tasmania and a strengthening of southwesterly circulation and neoglaciation in southern new zealand while the preceding period 800 1400 ad was less certainly marked by reduced westerly flow from modern records we know that decadal and inter annual variability is important e g pacific decadal oscillation high latitude mode also known as the antarctic oscillation el nino southern oscillation only a minority of the proxies examined can identify changes on these temporal scales but data from tree rings ice cores and laminated lake sediments do indicate systematic changes in these phenomena through time rossby wave patterns are shown to play a critical role in long duration events as well as at the synoptic scale we conclude that westerly circulation is as strong now as at any time in the last glacial cycle in addition changes in latitudinal boundaries in the westerlies may be nearly as large in inter annual zonal shifts ca 2 maximum as in glaciation interglaciation movements ca 3 4 there is however reasonable evidence of strengthening weakening across much of the westerly belt at westerly maxima minima such as the lia early holocene

influence of strike slip fault segmentation on drainage evolution and topography a case study the palomares fault zone southeastern betics spain abstract the palomares fault zone pfz is one of the main sinistral strike slip faults in the betics se spain with approximately 16 km of north south displacement the pfz initiated during the tortonian messinian as a transfer structure linking areas subject to nw se shortening during the plio quaternary the fault zone lengthened cutting previous fold structures and widened towards the east displacing the active mountain front to the western border of sierra almagrera sierra almenara these sierras which show moderate uplift rates of 0 05 0 15 m ka formed in response to the oblique slip regime of the pfz the drainage system in the vicinity of the pfz is asymmetric with respect to a main axial valley that runs parallel to the pfz on the downthrown fault block in this block the drainage density is lower and the streams are longer than in the uplifted block furthermore west of the main axial valley the streams describe eastward directed deflections indicating the progressive eastward migration of the main axial valley during the pleistocene the drainage system on the uplifted ranges shows a consequent pattern indicating recent uplift and folding under nnw sse convergence recent activity along segments of the pfz has increased topographical gradients favouring dissection of previous streams by headward erosion of streams transverse to the active fault segments

comparative uranium thorium and thermoluminescence dating of weathered quaternary alluvium in the tropics of northern australia abstract thermoluminescence tl age determinations of alluvial sediments in the tropics are evaluated by comparison with u th age determinations of pedogenic accumulations in the alluvium of the lower gilbert river a large fan delta in the wet dry tropics of northern queensland australia this study extends u th dating by applying it not only to calcretes but also to fe mn oxyhydroxide oxide accumulations while a direct correlation cannot be made between u th dates from secondary minerals and tl dates from the host sediments both sets of data show broad consistency in addition to providing a minima for acceptable tl ages u th dates are useful for determining the chronology of pedogenesis diagenesis they show that calcretes and ferricretes have formed under similar climatic conditions in the wet dry tropics of northern australia during the late pleistocene beneath about 5 12 m the gilbert fan delta consists of an extensive sand body older than 85 000 yr and probably about 120 000 yr in age representative of a period of major fluvial activity not repeated since this time above are muds and fine sandy muds that extend uninterrupted to the present surface except in the downstream fan where they are bisected by a thin unit of medium sand that tl dates at 40 000 50 000 yr b p a system of sandy distributary channels over the fan surface represents an early holocene fluvial phase probably more active than at present

anatomy of the dead sea transform does it reflect continuous changes in plate motion a new gravity map of the southern half of the dead sea transform offers the first regional view of the anatomy of this plate boundary interpreted together with auxiliary seismic and well data the map reveals a string of subsurface basins of widely varying size shape and depth along the plate boundary and relatively short 25 55 km and discontinuous fault segments we argue that this structure is a result of continuous small changes in relative plate motion however several segments must have ruptured simultaneously to produce the inferred maximum magnitude of historical earthquakes

localized versus distributed shear in transform plate boundary zones the case of the dead sea transform in the jericho valley 1 continental transform plate boundaries are typically either localized along a single usually segmented major fault or distributed over a broad deformation zone in the latter shear is partitioned between major strike slip faults and intervening often rotating fault systems analog and numerical simulations suggest that such internal fault systems evolve and may be localized or delocalized depending on strain and fault zone strength this paper examines the degree and evolution of shear localization in the jericho valley section of the dead sea transform dst which is part of the africa arabia plate boundary in this section the current breadth of the transform valley and its penetrative strain field are difficult to reconcile with localized shear we integrate newly acquired high resolution reflection data reprocessed exploration reflection data both focused to 2 5 3 5 km depth relatively relocated earthquake epicenters and fault plane solutions based on p wave first arrivals and suggest reinterpretations for previously published structural and seismic data in the jericho valley and the northern dead sea basin it is found that shear in this section of the dst evolved from an early probably miocene pliocene stage of localized strike slip motion primarily along the jericho fault to a late stage pliocene recent when shear has been distributed over internal fault sets that apparently lean against a major eastern dst segment in the early stage the jericho fault formed the western boundary of a deep narrow probably pull apart basin filled by fluvial clastics and evaporites this is overlain by the late stage broad basin characterized by low energy deposition of lacustrine and fluvial sediments pliocene rock salt has apparently utilized the jericho fault zone as a conduit for diapirism causing the uplift normal faulting and surface deformation of late pleistocene and holocene sediments currently observed along the 15 km long jericho lineament on the basis of the currently observed dextral normal motion across the internal nne ne trending fault system counterclockwise rotation is expected to have occurred within the transform zone these tectonic and depositional changes were probably associated with onset of transtension across the dst related to the previously postulated shift of the africa arabia euler pole of rotation in the pliocene

lacustrine fluvial interactions in australia s riverine plains climatic forcing of fluvial systems has been a pre occupation of geomorphological studies in australia since the 1940s in the riverine plain southeastern australia the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world surficial sediments and landforms exceed 140 000 yr in age and geomorphological change recorded in the fluvial fluvio lacustrine and aeolian features have provided a well studied record of quaternary environmental change over the last glacial cycle the region includes the willandra lakes whose distinctive lunette lakes preserve a history of water level variations and ecological change that is the cornerstone of australian quaternary chronostratigraphy the lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the australian continent to date the lake level and palaeochannel records in the lachlan willandra system have not been fully integrated making it difficult to establish the regional significance of hydrological change here we compare the willandra lakes environmental record with the morphology and location of fluvial systems in the lower lachlan an ancient channel belt of the lachlan willandra creek acted as the main feeder channel to willandra lakes before channel avulsion caused the lakes to dry out in the late pleistocene electromagnetic surveys geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion single grain optical dating of floodplain sediments indicates that sedimentation in the new middle billabong palaeochannel had commenced before 18 4 1 1 ka a second avulsion shifted its upper reaches to the location of the present lachlan river by 16 2 0 9 ka the timing of these events is consistent with palaeohydrological records reconstructed from willandra lakes and with the record of palaeochannels on the lachlan river upstream willandra lakes shows high inflows during the last glacial maximum 22 ka but their subsequent drying between 20 5 ka and 19 ka was caused by river avulsion rather than regional aridity this case study highlights the benefits of combining fluvial with lacustrine archives to build complementary records of hydrological change in lowland riverine plains

a multi method approach to dating the burial and skeleton of kiacatoo man new south wales australia kiacatoo man a large rugged aboriginal adult buried in the lachlan riverine plains of southeastern australia was discovered in 2011 laser ablation uranium series analysis on bone yielded a minimum age for the burial of 27 4 0 4 ka 2 single grain optically stimulated luminescence ages on quartz sediment in which the grave had been dug gave a weighted mean age of 26 4 1 5 ka 1 luminescence samples from the grave infill and from sediment beneath the grave exhibit overdispersed dose distributions consistent with bioturbation or other disturbance which has obscured the burial signal the overlap between the minimum u series and maximum luminescence ages places the burial between 27 0 and 29 4 ka 2 luminescence ages obtained from the channel belt of between 28 2 and 25 3 ka indicate that fluvial sedimentation was occurring before the last glacial maximum which is consistent with the broader geomorphic setting together these results are internally and regionally consistent and indicate that kiacatoo man was one of the more ancient individuals so far identified in australia his remains are important to our understanding of patterns of biological variation and other processes that have shaped people in the murray darling basin through time

gps evidence for northward motion of the sinai block implications for e mediterranean tectonics gps survey sites in the sinai peninsula show northerly motion relative to africa nubia at 1 4f0 8 mm yr north and 0 4f0 8 mm yr west continuous igs gps sites in israel west of the dead sea fault show a similar northerly sense of motion relative to nubia 2 4f0 6 mm yr north and 0 04f0 7 mm yr east suggesting that the entire sinai block south of lebanon is characterized by northward translation relative to the nubian plate we develop an elastic block model constrained by the gps results that is consistent with the regional tectonics and allows us to estimate slip rates for sinai bounding faults including the gulf of aqaba southern dead sea fault system 4 4f0 3 mm yr left lateral the gulf of suez 1 9f0 3 mm yr left lateral and 1 5f0 4 mm yr extension and the cyprus arc predominantly convergence at 8 9f0 4 mm yr along the western segment and 6 0f0 4 mm yr left lateral strike slip along the eastern segment these observations imply that the sinai peninsula and levant region comprise a separate sub plate sandwiched between the arabian and nubian plates d 2005 elsevier b v all rights reserved

stratigraphic architecture resulting from late quaternary evolution of the riverine plain south eastern australia the riverine plain of south eastern australia is the result of prolonged cenozoic fluvial activity single thread anabranching and distributary channels and floodplains and associated aeolian dunes characterize the uppermost sequences based on detailed interpretations of late quaternary fluvial sedimentation and surficial stratigraphy for this 77 000 km2 basin earlier prior stream and ancestral stream models of fluvial deposition deduced from limited stratigraphic and chronological evidence are replaced with aggradational palaeochannel and migrational palaeochannel models thermoluminescence dating reveals four distinct phases of palaeochannel activity between 105 and 12 ka the first coleambally phase late in oxygen isotope stage 5 the second kerarbury phase in stage 3 the third gum creek phase before and the fourth yanco phase after the last glacial maximum lgm in stage 2 the first three of these phases were characterized by mixed load laterally migrating sinuous palaeochannels with occasional transitions to a straighter bedload dominated mode and vice versa the first two phases concluded with a bedload dominated episode resulting in aggradational palaeochannels on the surface of the plain and the third phase prior to the lgm did also in its downstream reaches the phase following the lgm was characterized entirely by large mixed load sinuous migrational palaeochannels these exhibited no terminating bedload episode because the onset of holocene climates reduced the size of the flood peaks greatly diminished the supply of bedload from the upper catchments and resulted in streams evolving to their present highly sinuous suspended load form the result is a complex stratigraphic architecture consisting of vertically and laterally accreted units extending over hundreds of kilometres in the form of channel sand stringers sand sheets and derivative aeolian dunes partially or wholly encased in overbank fines

experiments on strike slip faulting and block rotation analogue model experiments investigating strike slip faulting in zones of distributed shear deformation show that fault orientations and fault evolution indicate modifications of the stress field with increasing bulk shear strain dextral bulk shear deformation at low strain is accommodated dominantly by synthetic strike slip faults riedel shears at higher strain secondary antithetic and synthetic faults develop mostly between earlier formed major riedel shears closely spaced parallel antithetic faults cross faults delimit domains that rotate about vertical axes with continuing shear deformation rotation of fault bounded domains results in sigmoidal antithetic faults that have a dip slip component and a dip direction that changes along strike there is good agreement between models and natural examples of distributed shear zones where block rotations about vertical axes have been documented

episodic fluvial activity of inland rivers in southeastern australia palaeochannel systems and terraces of the lachlan river inland rivers in southeastern australia preserve a long record of surface palaeochannels accompanied by alluvial terraces that reflect changes in water and sediment discharges from the southeastern highlands through much of the last glacial cycle a compilation of ages on rivers of the southern murray darling basin together with new dates from the lachlan river suggest that the fluvial response to climate change has been regionally consistent and responsive to climate change on timescales 10 ka for much of the last glacial cycle inland rivers were mixed load sinuous single and anabranching channels that carried bankfull discharges of between 3 and 11 times present day rivers incision of the upper alluvial plains and valleys occurred in the lead up to the coldest part of the last glacial cycle this was followed at 34 ka by the synchronous development of large meandering channels that may have been associated with lower evapotranspiration from alpine highland catchments accompanied by higher precipitation smaller channels and declining lateral channel sedimentation suggests arid climates during the last glacial maximum and late glacial period with seasonally large actively migrating channels being maintained in rivers dominated by snowmelt runoff from the australian alps during the holocene sensitivity to recorded changes in precipitation amounts and variability differed between catchments with some rivers constructing larger or more actively migrating channels in the early to mid holocene

the chronology of the last deglaciation implications to the cause of the younger dryas event it has long been recognized that the transition from the last glacial to the present interglacial was punctuated by a brief and intense return to cold conditions this extraordinary event referred to by european palynologists as the younger dryas was centered in the northern atlantic basin evidence is accumulating that it may have been initiated and terminated by changes in the mode of operation of the northern atlantic ocean further it appears that these mode changes may have been triggered by diversions of glacial meltwater between the mississippi river and the st lawrence river drainage systems we report here accelerator mass spectrometry ams radiocarbon results on two strategically located deep sea cores one provides a chronology for surface water temperatures in the northern atlantic and the other for the meltwater discharge from the mississippi river our objective in obtaining these results was to strengthen our ability to correlate the air temperature history for the northern atlantic basin with the meltwater history for the laurentian ice sheet

structural geometry and evolution of the dead sea jordan rift system as deduced from new subsurface data abstract analysis of deep drilling data and seismic reflection surveys obtained in recent years permit establishment of a tectonic model of the dead sea jordan rift system that is in part conformable with some of the many often controversial theories on this subject but which also introduces new information negating some concepts that are widely accepted in the literature the dead sea jordan rift system is not a tensional graben between two parallel sets of faults but instead can be best defined as a sinistral transform connecting an incipient oceanic ridge the red sea with an upthrusted collision zone the taurus range the shear is caused by the opening of the red sea and the motion of the arabian sub plate away from the african plate the shearing occurs along a largely south north trending slightly arcuate une consisting of a series of en echelon left stepping left lateral strike slip master faults of varying lengths these faults characteristically die out to the north by bending outward northeast and the movement is taken up by the strike slip faults to the left i e to the west where overlap of the two faults occurs very narrow and very deep grabens have evolved in places the width being equal to the depth the narrowness of these grabens is dictated by the closeness of the overlapping segments of the successive strike slip faults this feature points to the probability that the en echelon strike slip faults have a common root zone at great depth these grabens are not typical leaky pull aparts in that they have no gravimetric magnetic or heat flow anomalies nor are they closed on all four sides by large faults their northern ends are characterized by gradually rising graben floors without major diagonal cross faults the dead sea jordan rift system sensu stricto extends over a distance of 420 km from the northern shore of the gulf of elat to the northern margin of the hula valley southward it is connected with the red sea along the gulf of elat transition zone which has elements of strike slip as well as tensional opening a northern transition zone exists between the hula valley and the taurus arc where diminishing strike slip movement is compensated by several underthrust belts the time of the beginning of the movement along the rift can be established as pre middle miocene because mid miocene sediments overlie an upper cretaceous graben floor rifting has continued intermittently to the present volcanism in the northern fifth of the rift is genetically associated with the seismically active tensional golan hauran jebel drouz wadi sirhan tectonic trend which has a north west southeast orientation and not with the north south trending dead sea jordan rift

palaeosols and late pleistocene rainfall fluctuations in the negev desert the existence of a series of palaeosols in the present day desert region of southern israel the northern negev desert 1 2 indicates recurring periods of wetter climate in the past up to seven well developed palaeosols occur within a section and each has a horizon containing soft calcium carbonate nodules 3 15 mm in diameter the palaeosols are developed within loess or fluvially redeposited loess consisting of silty clay or clayey silt the 14c ages of the uppermost three calcic horizons average 13 000 yr bp calcic horizon ch i 28 000 yr bp ch ii and 37 000 yr bp ch iii drier phases occurred between these periods of pedogenesis especially during the last glacial maximum centred at 18 000 yr bp when extensive erosion occurred analysis of the 13c content of nodule carbonates points to the occurrence of strong north south rainfall gradients during each period of calcic horizon formation which excludes the possibility of monsoonal rains contributing to the increased rainfall during these periods the palaeosols correspond to global warm phases of the last glacial period

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

dynamics of sediment disturbance by periodic artificial discharges from the world s largest tidal power plant abstract to investigate the dynamics of sediment disturbance near the world s largest sihwa tidal power plant tpp two mooring observations have been conducted the mooring results show that current velocity and suspended sediment concentration ssc were significantly disturbed over various time scales on the short term flood ebb time scale resuspension of bottom sediment is mainly controlled by the strong jet flow 2 m s 1 and resulting anticlockwise rotating vortex associated with the artificial discharge during ebb phase the strong flow resulted in suspension of high concentration near bed sediment and seaward transport of the suspended sediment after turning to flood phase the vortex produced secondary ssc peaks transporting the suspended sediment toward the sihwa tpp the most active suspension of bed sediment predominantly occurred during 1 2 h immediately after the start of artificial discharge for the fortnightly spring neap time scale ssc during spring tide was approximately 2 5 times higher than that during neap tide during the combined period of ebb and spring tides in particular the periodic artificial discharge can enhance the responses of ssc in the vicinity of sihwa tpp

a shifting river of sand the profound response of australia s warrego river to holocene hydroclimatic change abstract in dryland river catchments palaeochannels provide some of the key records for understanding the changes in river character and behaviour that can occur in response to different extrinsic and intrinsic controls here we combine modern hydroclimatic datasets satellite imagery field surveys and optically stimulated luminescence osl dating of palaeochannels to investigate the response of the 850 km long warrego river located in central eastern australia to holocene hydroclimatic change the modern warrego is an intermittent to ephemeral low energy river unit stream power 4 w m 2 and is characterised by low sinuosity straight narrow

the repetition of large earthquake ruptures abstract this survey of well documented repeated fault rupture confirms that some faults have exhibited a characteristic behavior during repeated large earthquakes that is the magnitude distribution and style of slip on the fault has repeated during two or more consecutive events in two cases faults exhibit slip functions that vary little from earthquake to earthquake in one other well documented case however fault lengths contrast markedly for two consecutive ruptures but the amount of offset at individual sites was similar adjacent individual patches 10 km or more in length failed singly during one event and in tandem during the other more complex cases of repetition may also represent the failure of several distinct patches the faults of the 1992 landers earthquake provide an instructive example of such complexity together these examples suggest that large earthquakes commonly result from the failure of one or more patches each characterized by a slip function that is roughly invariant through consecutive earthquake cycles the persistence of these slip patches through two or more large earthquakes indicates that some quasi invariant physical property controls the pattern and magnitude of slip these data seem incompatible with theoretical models that produce slip distributions that are highly variable in consecutive large events

is the jericho escarpment a tectonic or a geomorphological feature active faulting and paleoseismic trenching abstract the jericho fault is considered to be the main active fault in the northern dead sea lower jordan valley in previous studies it has been identified by a prominent linear topographic escarpment that is thought to be the surface expression of this fault on land north of the dead sea in this study the paleoseismic natures of the escarpment and the fault were examined seismic activity was investigated in a series of three trenches excavated south of the fault trace on the surface these trenches show evidence for late holocene faulting a fourth trench excavated 300 m farther to the south exposed continuous finely laminated marl from the 80 ka samra formation at a depth of 2 0 6 m below the surface with no evidence of faulting this could suggest that the fault on land is segmented and that the nature of its activity changes from north to south toward the lake indeed the continuation of this fault under the waters of the dead sea reveals active faulting along a sharp segmented linear bathy

surface ruptures induced by the devastating 1068 ad earthquake in the southern arava valley dead sea rift israel abstract the elat fault a segment of the dead sea transform runs along the southern arava valley part of the dead sea rift israel forming a complex fault zone that displays a time dependent seismic behaviour paleoseismic evidence shows that this fault zone has generated at least 15 earthquakes of magnitude larger than m 6 during the late pleistocene and the holocene however at present the elat fault is one of the quietest segments of the dead sea transform lacking even microsesimicity the last event detected in the southern arava valley occurred in the avrona playa and was strong enough to have deformed the playa and to change it from a closed basin with internal drainage into an open basin draining to the south paleoseismological geophysical and archaeological evidences indicate that this event was the historical devastating earthquake which occurred in 1068 ad in the eastern mediterranean region according to the present study this event was strong enough to rupture the surface reactivate at least two fault branches of the elat fault and vertically displace the surface and an early islamic irrigation system by at least 1 m in addition the playa area was uplifted between 2 5 and 3 m along the eastern part of the elat fault shear zone such values are compatible with an earthquake magnitude ranging between m 6 6 and 7 since the average recurrence interval of strong earthquakes during the holocene along the elat fault is about 1 2 0 3 ky and the last earthquake occurred more about 1000 years ago the possibility of a very strong earthquake in this area in the future should be seriously considered in assessing seismic hazards

chronology of murrumbidgee river palaeochannels on the riverine plain southeastern australia four major periods of palaeochannel activity have been identified on the murrumbidgee sector of the riverine plain of southeastern australia on the basis of stratigraphic information the channels reveal a picture of changing flow conditions during the last full glacial cycle the ages of the periods were determined from nearly 40 thermoluminescence dates on surficial fluvial and aeolian sediments these are named the coleambally phase which occurred from 105 to 80 ka the mid to latter part of oxygen isotope stage 5 the kerarbury phase from 55 to 35 ka stage 3 the gum creek phase from 35 to 25 ka late stage 3 to early stage 2 and the yanco phase from 20 to 13 ka late stage 2 the present flow regime was established by about 12 ka stage 1 the first two phases correlate with episodes of enhanced fluvial activity in northern and central australia and with reduced dust activity globally the phases in stage 2 appear to be associated with seasonal snow melt and increased peak flows in periods flanking the last glacial maximum source bordering aeolian dunes associated with the coleambally kerarbury and yanco phases were found however the tl dates show that some have undergone aeolian reworking thermoluminescence dating and fluvial stratigraphy have revealed a detailed picture of late quaternary climate and flow regime changes that has the potential to extend to identified deposits stratigraphically older than those described here

holocene seismic and tectonic activity in the dead sea area abstract the dead sea is a large active graben within the dead sea rift which is bounded by two major strike slip faults the jericho and the arava faults we investigated the young tectonic activity along the jericho fault by excavating trenches up to 3 5 m deep across its trace the trenches penetrate through late pleistocene and holocene sediments we found that a zone up to 15 m wide of disturbed sediments exists along the fault these disturbed sediments provide evidence for two periods of intensive activity or more likely for two major earthquakes that occurred during the last 2000 years the earthquakes are evident in small faults vertical throw of a few layers cracks unconformities and wide fissures we further documented evidence for recent sinistral shear along the jericho fault in deformed sediments and damage to an 8th century palace on a subsidiary fault we suggest that the two earthquakes may be correlated with the 31 b c earthquake and the 748 a d earthquake reported by the ancients