seismic potential of the dead sea fault in the northern gulf of aqaba elat new evidence from liquefaction seismic reflection and paleoseismic data abstract the cities of elat israel and neighboring aqaba jordan are major economic cultural and seaport centers they are located on the northern shore of the gulf of aqaba elat gae directly on the dead sea transform yet the precise location of the fault trace and its tectonic activity are lacking the interpretation of seismic reflection profiles across the gae beach and paleoseismic trench data located 2 2 km north of the shoreline provide evidence that the active offshore mapped avrona fault extends onland along the eastern side of the elat sabkha mudflat where three prominent fault strands crosscut the sedimentary fill mismatch of reflector geometry across the faults and flower structures indicate strike slip faulting with a normal slip component subsurface data from two trenching sites provide evidence for a minimum of two surface ruptures and two paleoliquefaction events faulting is constrained by radiocarbon dating for an event 1 between 897 and 992 ce and event 2 after 1294 ce we suggest that the historically documented 1068 ce and at least one later earthquake in 1458 or 1588 ce ruptured the elat sabkha site based on fault mapping we suggest a minimum value of m 6 6 for the 1068 ce earthquake whereas no surface rupture was observed for the 1212 ce historical earthquake fluidized strata radiocarbon dated to before 1269 1389 ce identified as paleoliquefaction may be attributed to it two liquefaction sand blows mapped in the trench likely formed after 1337 ce and before 1550 ce which possibly occurred at the same time as in the second faulting event our data suggest that no large event occurred along the avrona segment in the past 430 550 years given a 5 mm yr slip rate we conclude that a significant period of time passed since the last surface rupturing on the avrona fault increasing its seismic potential

the seismicity along the dead sea fault during the last 60 000 years abstract evidence for unchanging slip rate and a gutenberg richter relation for earthquake distribution along the dead sea fault during the past 60 000 yr are presented the evidence comes from three different segments approximately 100 km apart and from three different timescales prehistoric paleoseismic historical and modern instrumental records the paleoseismic data are based on two different methods in the southern arava valley and the northern jordan valley segments the amount of normal displacement along several faults is used while in the dead sea basin the appearance of brecciated beds which are considered as seismites is used we found that for the southern arava valley segment a constant dip slip rate of 0 5 mm yr can explain the cumulative normal slip during the past 45 000 yr this suggests that normal faulting is only 10 of the total left lateral strike slip motion we also found that for all three segments the paleoseismic and historical records of strong earthquakes lie on the linear extrapolation of the frequency magnitude relation of the instrumental record the calculated b values for all three segments are between 0 85 and 1 similar to other major strike slip faults in the world it is concluded that the gutenberg richter distribution is a stable mode in the tectonic setting of the dead sea fault during the past 60 000 yr

modeling of seismic guided waves at the dead sea transform 1 on several recordings of linear seismometer arrays crossing the arava fault af in the middle east we see prominent wave trains emerging from in fault explosions which we interpret as waves being guided by a fault zone related low velocity layer the af is located in the arava valley and is considered the principal active fault of the mainly n s striking dead sea transform system in this section observations of these wave trains are confined to certain segments of the receiver lines and occur only for particular shot locations they exhibit large amplitudes and are almost monochromatic we model them by a two dimensional 2 d analytical solution for the scalar wave field in models with a vertical waveguide embedded in two quarter spaces a hybrid search scheme combining genetic algorithm and a local random search is employed to explore the multimodal parameter space resolution is investigated by synthetic tests the observations are adequately fit by models with a narrow only 3 12 m wide waveguide with s wave velocity reduced by 10 60 of the surrounding rock we relate this vertical low velocity layer with the damage zone of the af since the location of receivers observing and of shots generating the guided waves respectively match with the surface trace of the fault the thickness of the damage zone of the af at least at shallow depths seems to be much smaller than in other major fault zones this could be due to less total slip on this fault

s wave velocity images of the dead sea basin provided by ambient seismic noise abstract based on passive seismic interferometry applied to ambient seismic noise recordings between station pairs belonging to a small scale array we have obtained shear wave velocity images of the uppermost materials that make up the dead sea basin we extracted empirical green s functions from cross correlations of long term recordings of continuous data and measured inter station rayleigh wave group velocities from the daily correlation functions for positive and negative correlation time lags in the 0 1 0 5 hz bandwidth a tomographic inversion of the travel times estimated for each frequency is performed allowing the laterally varying 3 d surface wave velocity structure below the array to be retrieved subsequently the velocity frequency curves are inverted to obtain s wave velocity images of the study area as horizontal depth sections and longitude and latitude depth sections the results which are consistent with other previous ones provide clear images of the local seismic velocity structure of the basin low shear velocities are dominant at shallow depths above 3 5 km but even so a spit of land with a depth that does not exceed 4 km is identified as a salt diapir separating the low velocities associated with sedimentary infill on both sides of the lisan peninsula the lack of low speeds at the sampling depth of 11 5 km implies that there are no sediments and therefore that the basement is near 10 11 km depth but gradually decreasing from south to north the results also highlight the bowl shaped basin with poorly consolidated sedimentary materials accumulated in the central part of the basin the structure of the western margin of the basin evidences a certain asymmetry both whether it is compared to the eastern margin and it is observed in north south direction infill materials down to 8 km depth are observed in the hollow of the basin unlike what happens in the north and south where they are spread beyond the western dead sea shore

compiling an earthquake catalogue for the arabian plate western asia abstract the arabian plate is surrounded by regions of relatively high seismicity accounting for this seismicity is of great importance for seismic hazard and risk assessments seismic zoning and land use in this study a homogenous earthquake catalogue of moment magnitude mw for the arabian plate is provided the comprehensive and homogenous earthquake catalogue provided in the current study spatially involves the entire arabian peninsula and neighboring areas covering all earthquake sources that can generate substantial hazard for the arabian plate mainland the catalogue extends in time from 19 to 2015 with a total number of 13 156 events of which 497 are historical events four polygons covering the entire arabian plate were delineated and different data sources including special studies local regional and international catalogues were used to prepare the earthquake catalogue moment magnitudes mw that provided by original sources were given the highest magnitude type priority and introduced to the catalogues with their references earthquakes with magnitude differ from mw were converted into this scale applying empirical relationships derived in the current or in previous studies the four polygons catalogues were included in two comprehensive earthquake catalogues constituting the historical and instrumental periods duplicate events were identified and discarded from the current catalogue the present earthquake catalogue was declustered in order to contain only independent events and investigated for the completeness with time of different magnitude spans

estimating the age of desert alluvial surfaces with spaceborne radar data abstract we present a new dating approach for desert alluvial surfaces that utilizes radar image data to obtain regional scale correlations between dated surfaces and surfaces of unknown ages the study was carried out along the arava segment of the dead sea transform north of the gulf of elat aqaba using advanced land observation satellite alos phased array type l band synthetic aperture radar palsar data with 6 12 m pixel resolutions nineteen independently dated quaternary morphostratigraphic alluvial units 5 to 1910 ka from eight different sites with variable lithologies carbonate magmatic chert were examined in order to develop test and validate the proposed approach expanding on previous studies that established the characteristic smoothing of desert alluvial surface through time and the capability of measuring such roughness variations with radar we employed a pixel aggregation approach that yielded a robust r 2 0 95 power law relation between the average radar backscatter value from the surface ar and the abandonment age t of the unit as measured with independent methods such as luminescence and or cosmogenic radionuclide dating we found that 1 this ar t correlation can be inverted to obtain calibrated radar based t estimates as old as 1 5 ma with 35 uncertainty 2 alos palsar 6 m pixel images acquired at incidence angles of 34 38 yielded optimal results 3 a sample of at least 70 contiguous radar pixels was required to capture the natural roughness variability of the surfaces examined and 4 surface lithology did not exert a primary effect on t inversions validation experiments yielded radar based ages of 3 1 91 32 484 169 and 1604 561 ka that compare to holocene 56 14 540 60 and 1590 250 ka ages previously determined for the same surfaces respectively we propose that with region specific calibrations spaceborne radar data can be used to quantitatively estimate the age of abandoned alluvial units across regional scales

the somalia plate and the east african rift system present day kinematics summary the motion of the somalia plate relative to the nubia africa arabia and antarctica platcs is re evaluated using a new inversion method based on a monte carlo technique and a least absolute value misfit criterion a subset of the nuvel 1 data set with additional data along the levant fault and in the red sea is used the results confirm that the motion of arabia with respect to africa is significantly different from the motion relative to somalia it is further shown that the data along the sw indian ridge are compatible with a pole of relative motion between africa and somalia located close to the hypothetical diffuse triple junction between the ridge and thc east african rift the resulting africa somalia motion is then compatible with the geological structures and seismological data along the east african rift system assuming a separate somalia plate thus solves kinematic and geological problems around the afar triple junction and along the east african rift

new aspects of rhomb structures abstract the acute angles of 48 rhombic trapezoidal and triangular grabens horsts and upthrusts throughout the world were determined the results indicate an angular spread of 7 73 in most structures the two acute angles differ considerably most rhomb structures are grabens which show affinities to seismic faults and only a few are horsts and upthrusts in this connection modes of static crustal fracture propagation are compared to dynamic propagation rhomb structures occur along strike slip faults and in rifts these results question the universality of the pull apart model as a mechanism for rhomb structure development the two mechanisms that can lead to the formation of rhomb structures are 1 interaction of en echelon or non coplanar fractures by shear and extensional modes and 2 fracture bifurcation in an extensional mode the two mechanisms may result in faults of different shapes characterized by curved and straight boundaries respectively the grabens and horsts in extensional regions are the consequence of early fracture and later vertical displacements

stress field fluctuations along the dead sea rift since the middle miocene the dead sea transform dst is the suture between the african and the arabian plates both of which subduct northward under the eurasian plate the collision of these plates with eurasia and their relative motion are the source for their internal deformation especially in the vicinity of the dead sea transform geological observations indicate that two distinct paleostrain regimes operated adjacent to the dead sea rift and in the sinai israel subplate 1 wnw shortening less than 10 and nne extension beginning in the turonian is associated with the development of the syrian arc fold belt and attributed to the syrian arc stress field sas and 2 middle miocene to recent nnw shortening and ene extension associated with the 105 km sinistral displacement along the dead sea transform and the opening of the red sea is attributed to the dead sea stress field dss it was originally suggested that the sas terminated during the middle miocene with initiation of the dss however trend and age analysis of many structures shows that formation of sas compatible structures continued after the middle miocene up to the recent in some middle miocene and younger rocks structures such as faults dikes volcanic lineaments and tectonic stylolites compatible with both stress fields were reported in a few locations structures compatible with both stress fields crosscut each other it is suggested that the movements which resulted in the development of the syrian arc and other sas compatible structures are continuing to the recent and that dss movements are superimposed upon them the overlapping of sas and dss structures adjacent to the dst results from spatial and temporal fluctuations in the overall stress state we propose that such variations could be caused by the superposition of large earthquake stress drops associated with movements along the dst on a steady background plate scale stress regime associated with the sas thus dss compatible structures should form in preseismic activity periods when dst related elastic strain is high on the other hand the sas compatible structures should form during interseismic activity times subsequent to large local stress release along the dst

translocated plio pleistocene drainage systems along the arava fault of the dead sea transform abstract geomorphic and sedimentologic field studies and analyses of landsat 5 images and topographic maps indicate 15 km of left lateral displacement of a pliocene large stream and alluvial fans along the dead sea transform in southern israel and jordan in the central arava valley a rift valley located along the transform there is a notable discrepancy between the number and location of the feeding drainage basins within the eastern margins of the arava valley and those of the alluvial fans and the cross rift large stream a few of these large alluvial fans lack any feeding drainage basin furthermore east of the large stream there is no drainage basin that could have fed it these discrepancies between the physiography locations sizes and lithological compositions of the feeding drainage basins and of the alluvial fans can be explained by 15 km of left lateral movement since the late pliocene or the early pleistocene along the arava dead sea segment of the transform this is one of the largest displacements of a landform and surficial alluvial deposit in the world however the resulting average long term rate of movement is relatively small 0 3 0 75 cm year

paleohydrological implications of late quaternary fluvial deposits in and around archaeological sites in syria abstract the importance of fluvial processes to the development of late quaternary landforms in arid regions is well established particularly for the american southwest in contrast much less information exists about past fluvial processes for other arid regions such as arabic countries in the middle east this paper reviews the characteristics of late quaternary fluvial deposits and landforms in syria an arid country with little previous quaternary geomorphic research relatively detailed information has been obtained from areas adjacent to archaeological sites because of collaborative activities with geomorphologists and other geoscientists such activities have resulted in intensive field surveys and associated results of complementary archaeological studies of lithic artifacts are useful for establishing the chronology of fluvial deposits although the number of existing studies is limited the available information points to marked changes in the mode of fluvial processes in response to late quaternary climatic change fluvial sedimentation was enhanced during the wet periods of mis 3 4 the pleistocene holocene transition and the mid holocene in contrast the lgm was characterized by limited fluvial sedimentation under a drier climate as well as enhanced carbonate precipitation near the land surface to form calcrete and oncoids

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

active tectonics along the wadi araba jordan valley transform fault a geological study has been carried out along the 200 km long wadi araba following the transform fault that separates the arabian and sinai african plates recent movements along this structure affect upper pleistocene holocene deposits and archaeological sites kinematic indicators show sinistral strike slip and oblique movements in agreement with the relative motion between the two plates other evidence of recent horizontal displacement exists along the jordan valley fault both on the dead sea lake tiberias segment and on the segment north of lake tiberias a minimum horizontal slip rate of 1 cm yr 1 has been estimated for both the southern segment of the wadi araba fault and for the southern jordan river fault the two faults can be roughly subdivided into at least four segments two in the wadi araba 80 km long each one from the dead sea to lake tiberias 130 km and one from lake tiberias to the hula graben 30 km faulting may also occur along shorter subsegments as shown by bends in the wadi araba jordan river fault and by the growth of local compression and extension features instrument recorded seismicity appears to be mainly concentrated along some of these subsegments a comparison between the observed seismic and field determined slip rates across the fault indicates possible strain accumulation during the last 2000 years

holocene paleotemperatures deduced from geothermal measurements abstract detailed measurements of temperature and rock thermal properties were carried out in a 1000 m deep borehole drilled in massive granite using a suitable reduction these measurements reveal a coherent variation of apparent heat flow with depth which is attributed to past variations of the ground temperature during the last 10 000 years two inversion techniques of the data are described in order to reconstruct these paleotemperatures a classical inversion method allows a discussion of the information content of the data but leads to unreasonable temperature variations another method using bounds on paleotemperature variations provides more acceptable temperature models the main features of these models are the presence of a cold event identified as the little ice age and of warm episodes around 1500 bc and at the beginning of the present century the amplitude of the inferred variations would be at least 1 09 c

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

earthquake fault superhighways abstract motivated by the observation that the rare earthquakes which propagated for significant distances at supershear speeds occurred on very long straight segments of faults we examine every known major active strike slip fault system on land worldwide and identify those with long 100 km straight portions capable not only of sustained supershear rupture speeds but having the potential to reach compressional wave speeds over significant distances and call them fault superhighways the criteria used for identifying these are discussed these superhighways include portions of the 1000 km long red river fault in china and vietnam passing through hanoi the 1050 km long san andreas fault in california passing close to los angeles santa barbara and san francisco the 1100 km long chaman fault system in pakistan north of karachi the 700 km long sagaing fault connecting the first and second cities of burma rangoon and mandalay the 1600 km great sumatra fault and the 1000 km dead sea fault of the 11 faults so classified nine are in asia and two in north america with seven located near areas of very dense populations based on the current population distribution within 50 km of each fault superhighway we find that more than 60 million people today have increased seismic hazards due to them

the use of acoustic imaging to reveal fossil fluvial systems a case study from the southwestern sea of galilee abstract the analysis of reflected high resolution seismic data shows a distinct separation of regions with good and poor seismic penetration additional analysis of core data revealed good correlation between grain size and seismic penetration as a case study a shallow geophysical survey using a chirp profiler was conducted in the southwestern part of the sea of galilee by correlating the seismic and core data we found that areas with good seismic penetration represent coarse clastics while poor seismic penetration is related to fine clays new detailed bathymetric mapping and bottom morphology images combined with the penetration characteristics of the chirp signal reveal a large alluvial fan consisting mainly of coarse material sand to pebbles a fine grained band of mostly clay size material associated with an asymmetric bathymetric channel continues the trend of the old entrance of the yavniel creek into the sea of galilee we interpret the fine clay stripe to be a low energy streambed of the yavniel creek the clear relations between the reflected chirp signal and the grain size of the water bottom sediments suggests that this type of survey can be used to characterize depositional environments

tectonics of the pliocene homs basalts syria and implications for the dead sea fault zone activity timing of activity along the yammuneh segment lebanon syria of the dead sea fault zone and its northward continuation is still a subject of controversy our field structural analysis and observations on radar landsat and digital elevation model imagery of the homs region syria are of concern for plio quaternary tectonics of the whole northern part of the dead sea fault zone we show in this paper that the northern dead sea fault zone has remained active since the onset of the homs basalts at c 6 ma continuing movement in recent times is indicated by the occurrence of quaternary pull apart structures and offset of active ravines along the fault the homs basalts are related to the distinct oval shaped shin volcanic edifice of which the long axis trends nw the volcano was fed through nw striking tension fractures which now form dykes and volcanic ridges these patterns are consistent with a ne sw extension that occurred c 6 ma ago the northwestern end of the shin volcano is left laterally displaced c 20 km yielding a c 3 3 mm a 1 mean rate of relative movement between the arabian and african plates in the northern part of the dead sea fault zone the overall trace of the main active dead sea fault zone is not a single transform but forms an irregular plate boundary composed of transform fault and collision belt segments fine grained mylonite developed in the fault corridor may have favoured aseismic deformation in the shin volcano area

northward migration of the southern diagonal fault of the hula pull apart basin dead sea transform northern israel abstract the hula valley located in northeastern israel is a 4 million year old pull apart basin bounded by two left stepped segments of the dead sea transform basic models of pull apart basins suggest four faults at all sides of the basin a situation which is not always the case in the hula pull apart basin the longitudinal n s faults are clearly evident while the transversal e w faults are less explicit an nw oriented lineament expressed as a north facing continuous scarp 1 3 m high was recognized in the southern part of the valley morphological seismic and sedimentary considerations suggest that this scarp is the surface expression of a deep seated fault this fault termed the yesod hama ala fault forms the present southern boundary of the hula pull apart basin and appears to be the southern diagonal fault which links the jordan fault in the east with the yammunneh fault in the west it is suggested that this fault scarp formed a shallow morphological barrier that partly blocked the southern outlet of the valley enabling a permanent lake in the southern part of the hula valley thus the uplifted southern block determined the sw shoreline of the lake it is proposed that the hula basin is a version of the classic pull apart model it is also suggested that in the absence of upwelling mantle material and extension along the length of the basin a crustal thinning and subsidence might have occurred through normal faulting of the upper brittle crust the thick depositional sequence within the southern part of the basin shows that the present margins have been a major depositional site for a long time and that the hula valley has thus developed as an asymmetric pull apart rhomb shaped basin bounded by steep north striking boundary normal as well as strike slip faults w nw striking and northward dipping normal faults and a south facing bending flexure as activity within the basin continued and northward migration of the faulting occurred a new fault developed according to this perception the present active fault is the yesod hama ala fault while the future fault will be located northward as can be presumed from the present micro seismic activity in the valley

ground temperature histories in eastern and central canada from geothermal measurements evidence of climatic change abstract inverse and direct methods have been used to analyze a large number of borehole temperature logs in order to infer past climatic changes results indicate a warming of 1 2 c in eastern and central canada during the past 150 years a period of cooling between 500 and 200 years before present corresponding to the time of the little ice age has also been identified in the same areas a regional ground temperature history is estimated for eastern and central canada from the simultaneous inversion of several temperature logs the inferred temperature changes appear correlated with the concentration of atmospheric carbon dioxide as reported from a greenland ice core and agree with existing meteorological and dendrochronological records for the area

stromatolites in caves of the dead sea fault escarpment implications to latest pleistocene lake levels and tectonic subsidence abstract a varied assemblage of algal stromatolites was encountered in caves along the northern section of the dead sea fault escarpment the caves are situated at the lower part of the escarpment at altitudes 310 to 188 m relative to mean sea level m s l i e ca 110 230 m above the present dead sea level the cave stromatolites are mainly composed of aragonite yielding u th ages of 75 17 ka the altitude mineralogy and ages as well as comparison with previously documented stromatolite outcrops in the area ascribe the cave stromatolites to the aragonite precipitating hypersaline lake lisan the late pleistocene predecessor of the dead sea the stromatolites are used as a lake level gauge based on the algae being reliant upon the light of the upper water layer preservation of the original structure and aragonite mineralogy of the stromatolites suggests a closed system regarding the radioactive elements enabling reliable u th dating a curve of lake lisan levels is constructed based on the stromatolite ages and cave elevations the following points are noted 1 lake levels of 247 m relative to m s l are recorded at 75 72 5 ka 2 relatively high lake levels above 220 m relative to m s l are achieved at 41 5 ka and are still recorded at 17 ka 3 the peak level is 188 m relative to m s l at 35 5 29 5 ka these results indicate lake stands up to 80 m higher than previously accepted for large parts of the lake lisan time span this difference is explained by tectonic subsidence of up to 2 2 m ka within the dead sea depression since the latest pleistocene this subsidence rate is in the same order of magnitude with previously calculated subsidence rates for the dead sea depression begin z b zilberman e 1997 main stages and rate of the relief development in israel geological survey of israel report jerusalem unlike previous lake lisan level estimations the new curve is measured at the relatively stable shoulders of the dead sea depression

geological events in the bible the books of the bible contain numerous frequently very exact descriptions of geological events some of these are discussed here earthquakes and their accompanying landslides the crossing of the river jordan seiches and tsunamis the flood flooding sodom and gomorrah faulting burning gas seepages the burning bush and volcanism mount sinai these geological events appear in the biblical text mainly for artistic reasons they serve as a suitable background to dramatize the biblical account they create a supernatural atmosphere for the main stories but the time and place at which they occurred are of no importance to the narrator and might be shifted freely

geometrical statistical modelling of systems of fracture zones along oceanic ridges summary a mechanical statistical model is presented that aims to help to understand the history and geometry of the process of formation of fracture zones along oceanic ridges it uses ideas of statistical fracture theory used in engineering namely the weibull fracture model the approximate parallelism of the fracture zones along ridges makes it possible to use a onedimensional point process model with points along the ridge axes which represent the transform faults the ratios of the lengths of the corresponding fracture zones to the ocean width are used to obtain a rough estimate of the weibull modulus which is an important material parameter in fracture theory the theory is refined by introducing a hard core point process model the corresponding positive minimum distance between subsequent fracture zones results from stress relaxation in the vicinity of a given fracture zone

holocene earthquakes inferred from a fan delta sequence in the dead sea graben abstract the holocene sequence of the fan delta of nahal darga in israel records deformation associated with earthquakes related to the dead sea transform in general and to the jericho fault in particular the fan delta sequence is well exposed and 20 radiocarbon ages help to date the earthquakes that are inferred from a displacement along faults b liquefaction features associated with 11 separate sandy and silty layers and c slumped allocthonous bodies of sediments located directly above one of the main splays of the jericho fault on average an earthquake larger than m 5 5 has occurred approximately every 600 years this estimate is based on the earthquake record of the complete stratigraphic sequence with erosional hiatuses omitted from the calculations the most recently deformed layer is related to the 1927 jericho m l 6 2 earthquake this layer provides a modern analog for the style of soft sediment deformation associated with earthquakes in the late pleistocene and holocene silty sand beds of the fan delta complexes of the dead sea and its predecessor lake lisan

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

quaternary palaeogeomorphologic evolution of the wadi faynan area southern jordan abstract the faynan area comprises a complex assemblage of deposits and landforms of varying nature age and position in the landscape the dominant facies are fluvial slope and aeolian at least eight palaeochannels are present at different heights within the wadis dana and ghuwayr fewer terraces are preserved in the wadi faynan planated surfaces leaving low gradient straths rock cut channels and fluvial deposits are all evident the continuing drop in regional base level as a result of subsidence of the dead sea trough has driven incision and aided in the retention of many of the terrace deposits as they have been abandoned as the wadi systems have eroded downwards calcretisation has enhanced the preservation potential of many of the fluvial deposits a large proportion of these deposits are comparable to those found in the modern wadi systems and it is thought that they formed under arid conditions similar to those that exist today two of the terrace deposits appear to reflect slightly wetter conditions as they consist of finer grained better sorted materials and display evidence of biological activity there are at least four distinct alluvial fan and slope deposits that have formed at the edge of various mountain fronts the fans have been entrenched to varying degrees and are likely to have formed at different times in the quaternary possibly when conditions were more humid or during periods of increased tectonic activity aeolian deposits indicate a marginally drier phase in the late glacial maximum and similar sediments of mid holocene age could either reflect increasing aridity at this time as has been suggested by frumkin et al 1991 and or be a result of the increasing impact of humans on the landscape many of the deposits are beyond the age range of optically stimulated luminescence osl and radiocarbon dating techniques but a proposed stratigraphy is supported by some numerical dates on the younger deposits and associated archaeological artefacts

continental transforms a view from the alpine fault abstract continental transform faults are dominantly highly localized strike slip shear zones hundreds of kilometers long that accumulate tens to hundreds of kilometers of displacement from work on the alpine fault we pose the questions what is the deep structure of a continental transform and how does the displacement become localized we review research on the alpine fault and propose a model in which the fault partitions at depth into a steep zone extending into the mantle with largely fault parallel motion and a flat ductile decollement in the lower crust the fault localizes around two thirds of the plate motion within a 100 km wide zone of distributed deformation a review of other active continental fault systems suggests that variation between them may reflect their tectonic origins the nature of the crust in which they develop the presence of a significant oblique component of motion and the displacement rate all however have evidence for the development of a single principal fault zone that carries 50 of the total displacement and extends as a localized zone of shear into the upper mantle we review mechanisms of strain weakening and suggest that localization of a principal fault may be initiated in the seismogenic crust and through a series of positive feedbacks eventually extend through the lower crust into the upper mantle

geological structure of the eastern side of the lower jordan valley dead sea rift reflection seismic evidence abstract interpretation of recently released seismic reflection lines from the shuna eastern jericho basin combined with re analysis of the lithologic logs of the deep jv 1 and jv 2 boreholes provide new insights into the structure of the sedimentary basin that formed along the dead sea transform fault north of the dead sea in jordan we identified four major seismic boundaries in the reflection profiles the upper two were correlated with borehole stratigraphy these reflection boundaries include the top of the pan african basement r4 the base of the mesozoic r3 the base of the cretaceous r2 and the base of the post eocene section r1 the latter records sedimentation during the dead sea transform tectonic regime the total thickness attained by the older sedimentary units late cretaceous through cambrian is apparently less than 2 km we identified a subsurface structure a faulted monocline with a n s trend sub parallel to the strike of the dead sea transform that is named here al kharrar monocline the al kharrar structural ensemble is buried by syntectonic lacustrine and fluviatile sediments of the jordan valley group the structure formed as part of the dead sea transform deformation overprinting the late cretaceous syrian arc folds continued tectonic deformation is evident from the prominent unconformity at the base of post eocene syntectonic deposits that dip nw w and s away from the structural high along the nw flank of the al kharrar monocline syntectonic sediment thickness is generally less than 0 5 km while along the sw flank it thickens rapidly to nearly 1 km at the southern end of the interpreted seismic lines this rapid southern subsidence probably continues into the north end of the dead sea basin the lake s shoreline being located less than 3 km to the south young bifurcating faults with reverse slip components cutting the eastern part of the al kharrar monocline are attributed to a positive flower structure this pattern suggests strike slip with localized active compression northeast of the dead sea it may result from local transpression between fault strands that appear to be a northward continuation of the eastern boundary fault of the dead sea basin

indicators of faulting events and periods of quiescence in desert alluvial fans the main objective of the present paper is to present an integrated approach to the study of faulting stages in coarse alluvial deposits the study site is the alluvial fan of nahal shehoret presently under an extremely arid regime the exposure of fault scarps on the fan surfaces enables the identification of several geomorphic indicators employed in analysing and separating faulting events and periods of quiescence a the nature of fault scarp topography b soil catenary development on fault scarps c buried paleosols in alluvial deposits d colluvial bodies e rotated clasts along fault planes these indicators enable us to determine at all sites studied the total amount of displacement to separate faulting events and the amount of their displacement per event and to evaluate scarp stability and the duration of periods of tectonic quiescence

reconstruction of the 500 year ground surface temperature history of northern awaji island southwest japan using a layered thermal property model abstract changes in the ground surface temperature gst propagating underground can be recorded as thermal perturbations to the background thermal field this paper presents a forward model of conductive propagation of gst in a layered material model with uniform thermal properties in each layer and a series of step functions as gst history this model which is expressed using the same mathematical form of that for a uniform thermal property model with a series of step functions as gst history calculates subsurface temperature perturbations that originate from the gst change by superimposing numerically solved solutions of the model with surface boundary condition of a unit function using this model we reconstruct the recent 500 year gst history from borehole temperature data in northern awaji island southwest japan by bayesian inversion the reconstructed gst history shows the onset of warming in the mid 18th century to the early 19th century and an increase of 1 1 1 3 k up to the mid 20th century from the middle to late 20th century the gst decreased by about 0 2 k the gst change in the 20th century fits the trend of mean annual surface air temperature records in kobe opposite the coast of northern awaji island the gst history in northern awaji island differs from that in ulsan in the southeastern republic of korea which is located at the same latitude as northern awaji island differences of the gst histories of these regions most likely reflect differences in sea surface temperatures in these regions

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

seismic reflection across a continental transform an example from a convergent segment of the dead sea rift three seismic reflection lines in the dead sea rift in northern israel cross the transform plate boundary between arabia and the sinai block of the african plate the arabian plate edge consists of the meshoshim tilted block which we suggest to be partly a result of prerift activity in the sinai block the elevated rosh pinna saddle is faulted over the meshoshim block with a vertical separation of 2 5 3 km much of this separation is due to young reverse faulting which is related to the oblique plate boundary in this area the main fault zone transfers the motion from the western margin of the kinneret zemah graben to the eastern margin of the hula graben immediately north of lake kinneret the main fault is a 1 to 2 km wide zone of extensive deformation and a discrete main fault trace is hard to define further to the north the deformation is less extensive and is concentrated in a narrow fault zone deformation across the plate boundary is asymmetrical and while the meshoshim block is quite coherent the rosh pinna saddle is a highly faulted and deformed positive flower structure

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

implementation of magnetic gravity and resistivity data in identifying groundwater occurrences in el qaa plain area southern sinai egypt abstract el qaa plain is one of the areas that have been proved to be promising as to its soil and groundwater resources in the southwestern part of sinai this study was carried out to study the lateral and vertical variations in the subsurface lithologic properties in el qaa plain area and delineating the subsurface structure that affecting el qaa plain depression gravity magnetic data fifty one 51 vertical electrical sounding ves s and digital elevation model dem map were used two dimensional density modeling analytical signal tilt derivatives euler deconvolution techniques and interpretation of the resistivity data were applied on potential data this study concluded that el qaa plain is a ne sw depression confined by two normal faults and subdivided into five sedimentary units rock fragments and boulders derived to the plain from the surrounding highlands are the main components of the first surface unit that characterized by high resistivity values this layer is overly another unit composed of gravelly sand with thickness ranging between 10 and 140 m the third unit is composed mainly of sand with intercalations of clay with thickness ranging from 2 to 152 m a reefal limestone unit is a fourth unit interpreted from this study the fifth unit is composed of clay the water bearing formations in el qaa plain area are located principally in the second and the third layers finally the depth to the basement surface ranges from 400 m to more than 1 5 km below sea level also there are many minor structural trends interpreted from this study and affecting the el qaa plain are striking in n s e w and ne sw directions

geothermics and climate change 2 joint analysis of borehole temperature and meteorological data long period ground surface temperature variations contained in borehole temperature depth profiles form a complementary climate change record to high frequency but noisy surface air temperature sat records at weather stations we illustrate the benefits of jointly analyzing geothermal and meteorological data for two regions in utah where both high quality temperature depth measurements and century long sat records exist transient temperature depth profiles constructed from sat time series reproduce in considerable detail borehole transient ternperature depth profiles typical rms differences between these transient temperature profiles are less than 13 mk the analysis yields a preobservational mean pom temperature a parameter describing the long term mean surface temperature prior to the onset of sat measurements i e prior to the 20th century the average pom for these two regions is 0 6 0 2 c cooler than the 1951 1970 average sat suggesting that 20th century warming represents a real and significant departure from 19th century surface temperature values in certain cases borehole temperature profiles might be used as an independent check on long wavelength adjustments made to sat data

heat flow density values and paleoclimate determined from stochastic inversion of four temperature depth profiles from the superior province of the canadian shield abstract it has long been recognized that terrestrial heat flow density observations from boreholes may be biased due to non steady surface temperature conditions this calls for paleoclimatic corrections which have conventionally been obtained by solving a forward problem based on the equation of heat conduction and models of the surface temperature history and the thermal properties structure while computationally convenient the forward method fails 1 1 to provide a stringent quantitative representation of all available data with confidence limits 2 2 to extract all available information in an optimum manner 3 3 to provide confidence limits on the parameters of interest a stochastic inverse method which overcomes these shortcomings is described the method treats the surface temperature history the thermal conductivity structure and the background heat flow as unknowns which have been constrained a priori with soft bounds the bounds ensure numerical stability and prevent unrealistic solutions when the a priori hypothesis is safe the technique is applied to geothermal data from four 600 m deep boreholes in the superior province of the canadian shield the examples show how it is possible to constrain simultaneously the recent surface temperature history and the steady state background heat flow from shallow geothermal data and furthermore show how uncertainty about the average ground temperature during the wisconsin glaciation may be taken into account

a case study of sub basalt imaging in land region covered with basalt flows in this study a set of 20 2d seismic lines acquired over the golan heights basaltic plateau was processed and analysed although the data were acquired and processed by standard techniques in some cases good quality seismic images were obtained under several hundred metres of basalts we describe how the seismic characteristics of the top basalt layer were defined and show the effect of the numerous widespread volcanic sources on the quality of the final images the new data reveal the first images of the sedimentary sequence under the basalt flows and indicate that strands of the dead sea transform extend into this area the entire region was found to be very deformed several attractive traps for hydrocarbon exploration were also identified on the output sections

climate change on the colorado plateau of eastern utah inferred from borehole temperatures temperature profiles from boreholes on the colorado plateau of southeastern utah have been examined for evidence of climate change because these boreholes penetrate layered sedimentary rocks with different thermal conductivities bullard plots temperature versus integrated thermal resistance are used to estimate background heat flow and surface temperature intercepts reduced temperatures which represent departures from a constant heat flow condition are inverted for a surface ground temperature history at each borehole site using a singular value decomposition algorithm singular value cutoffs are selected by analyzing the spectral energy and the standard deviation of the model fit to the data as a function of the number of eigenvalues solutions are constructed from areas of large spectral energy and a cutoff where additional eigenvalues fail to improve the solution significantly the solution is parameterized in terms of 13 time steps increasing in duration and going back 400 years eight of nine borehole sites indicate between 0 4 and 0 8 c 0 2 c warming over the past 200 years with some evidence for accelerated warming in this century one borehole indicates local cooling over the same time period the amplitude of the warming inferred from borehole temperatures is less than that deduced from analysis of 100 year surface air temperature records at four of the five weather stations surrounding the borehole sites

relief inversion in the avrona playa as evidence of large magnitude historical earthquakes southern arava valley dead sea rift the arava valley section of the dead sea transform dst in southern israel is characterized by the absence of seismic activity in recent times however paleoseismic analysis of sediments in the avrona playa a pull apart basin along the dst reveals that at least six m 6 tectonic events have affected the avrona playa in the last 14 000 yr the recurrence interval of the events is approximately 2000 yr trenched normal faults and push up ridges in the playa show that the upper 2 m of the deformed sedimentary sequence consists of playa deposits with uniform soil development the deformed sediments and the soil are typical of basins with an endoreic fluvial system based on the limiting age of the sequence and the extent of soil development faulting in the playa followed by compression and uplift occurred in the last 1000 yr this most recent tectonic event displaced the surface by at least 1 m consistent with a m 6 5 earthquake this earthquake changed the morphology of the avrona playa from a closed system with internal drainage to an open basin resulting in relief inversion the seismic quiescence in the arava may indicate a seismic gap in this segment of the dst

three dimensional elastic earthquake modelling based on integrated seismological and insar data the mw 7 2 nuweiba earthquake gulf of elat aqaba 1995 november summary the nuweiba earthquake 1995 november 22 m w 7 2 the largest seismic event along the dead sea transform dst in at least 160 yr ruptured 45 50 km along the aragonese segment of the left stepping strike slip fault system occupying the gulf of elat aqaba southern segment of the dst the rupture initiated in a partly normal low slip first subevent near the southern end of the fault and propagated unilaterally north northeastward as a high slip nearly pure sinistral second subevent which was responsible for over 90 per cent of the total seismic moment the source mechanism and slip distribution derived from inversion of teleseismic broad band waveforms are used to construct a 3 d elastic model of the earthquake based on the boundary elements method resulting in the full 3 d displacement and stress fields induced by the earthquake in the absence of sufficient global positioning system data the only other constraints on the geometry and slip distribution of the rupture are provided by interferometric synthetic aperture radar insar measurements spanning the coseismic and early post seismic period we calculate simulated interferograms by transforming the calculated surface displacement field into the satellite coordinate system and comparing them with the observed interferograms the model parameters are then iteratively modified until a best fitting model is obtained providing a refined set of static source parameters for the mainshock this model is then used to calculate the static coulomb stress changes induced by the mainshock on the step over faults suggesting that the major m w 5 aftershocks in the first eight post seismic months were triggered by small changes 1 bar in the left lateral coulomb stress with effective friction coefficient not higher than 0 2 aftershock distribution and mechanisms indicate that the available coulomb stress dropped below the frictional strength of the fault but was not complete

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

magnetic character of a large continental transform an aeromagnetic survey of the dead sea fault new high resolution airborne magnetic hram data along a 120 km long section of the dead sea transform in southern jordan and israel shed light on the shallow structure of the fault zone and on the kinematics of the plate boundary despite infrequent seismic activity and only intermittent surface exposure the fault is delineated clearly on a map of the first vertical derivative of the magnetic intensity indicating that the source of the magnetic anomaly is shallow the fault is manifested by a 10 20 nt negative anomaly in areas where the fault cuts through magnetic basement and by a 5 nt positive anomaly in other areas modeling suggests that the shallow fault is several hundred meters wide in agreement with other geophysical and geological observations a magnetic expression is observed only along the active trace of the fault and may reflect alteration of magnetic minerals due to fault zone processes or groundwater flow the general lack of surface expression of the fault may reflect the absence of surface rupture during earthquakes the magnetic data also indicate that unlike the san andreas fault the location of this part of the plate boundary was stable throughout its history magnetic anomalies also support a total left lateral offset of 105 110 km along the plate boundary as suggested by others finally despite previous suggestions of transtensional motion along the dead sea transform we did not identify any igneous intrusions related to the activity of this fault segment

tectonic evolution of the qumran basin from high resolution 3 5 khz seismic profiles and its implication for the evolution of the northern dead sea basin abstract the dead sea basin is a morphotectonic depression along the dead sea transform its structure can be described as a deep rhomb graben pull apart flanked by two block faulted marginal zones we have studied the recent tectonic structure of the northwestern margin of the dead sea basin in the area where the northern strike slip master fault enters the basin and approaches the western marginal zone western boundary fault for this purpose we have analyzed 3 5 khz seismic reflection profiles obtained from the northwestern corner of the dead sea the seismic profiles give insight into the recent tectonic deformation of the northwestern margin of the dead sea basin a series of 11 seismic profiles are presented and described although several deformation features can be explained in terms of gravity tectonics it is suggested that the occurrence of strike slip in this part of the dead sea basin is most likely seismic sections reveal a narrow zone of intensely deformed strata this zone gradually merges into a zone marked by a newly discovered tectonic depression the qumran basin it is speculated that both structural zones originate from strike slip along right bending faults that splay off from the jordan fault the strike slip master fault that delimits the active dead sea rhomb graben on the west fault interaction between the strike slip master fault and the normal faults bounding the transform valley seems the most plausible explanation for the origin of the right bending splays we suggest that the observed southward widening of the dead sea basin possibly results from the successive formation of secondary right bending splays to the north as the active depocenter of the dead sea basin migrates northward with time

crustal structure of the dead sea basin from local earthquake tomography summary new findings of the velocity structure of the crust across the dead sea basin are obtained by applying tomography based method to local earthquakes we use p wave traveltime of 614 earthquakes that occurred in the dead sea basin in 1983 2009 at all depths the dead sea basin is characterized by lower velocities relative to both the eastern and western sides of the basin there is significant seismic activity at a depth of about 20 km mainly in the centre and the northern part of the basin at shallow depths 15 km there is more seismic activity on the eastern side of the basin than on the western side and the northern basin is generally more active than the southern basin asymmetry is also observed in the faults that border the dead sea basin the arava fault on the eastern side with nearly vertical dip faulting appears to be a clear boundary at all depths down to about 20 km the depth extension of the jericho fault on the western side of the basin is definitely limited to less than 15 km at greater depths of 20 km or more the western side is only partially bounded by a fault the concentration of earthquakes in the central part of the basin at depths larger than 15 km suggests that the dead sea fault at those depths acts as one single fault that is located in or near the central axis of the basin the existence of a number of clusters of earthquakes that spread from shallow depths of a few kilometres up to a depth of about 22 km points to several defined faults that traverse the dead sea basin one such example is the aftershock sequence of the 2004 earthquake that occurred in the northern dead sea basin seismic activity near mt sodom is relatively low and occurs at shallow depths down to 10 km whereas at larger depths 15 km it ceases this implies that the whole structure is relatively shallow with no wide and deeper extension seismic activity near and within the lisan peninsula extends to somewhat larger depths 15 km and then it ceases the occurrence of earthquakes at large depths suggests that the upper and the lower crust are relatively cool as was also suggested by earlier studies pointing to the fact that the heat flow is significantly below the global average value

effects of subsurface heterogeneity on the inference of climate change from borehole temperature data model studies and field examples from canada all existing approaches to the analysis and interpretation of borehole temperatures in terms of a ground surface temperature history are based on the one dimensional theory of heat conduction deviations from this idealization are manifest as noise in the interpretation we present numerical experiments that explore the effects of three dimensional subsurface heterogeneity on ground surface temperature histories inferred from borehole temperature profiles inversions of steady state temperature profiles containing such three dimensional noise reveal that in an inversion formulation incorporating a priori information spurious temperature histories can emerge when the a priori constraints on subsurface temperatures and thermophysical properties are too tight i e when arbitrarily small variations in subsurface temperatures and thermophysical properties are interpreted to have significance for the derived climate history relaxation of the a priori constraints enables an effective muting of the spurious histories similar experiments conducted on synthetic transient signals confirm the steady state results but also reveal that relaxation of the a priori constraints will also lead to a loss of signal if the level of relaxation is excessive our experiments suggest that relaxation of constraints on thermal conductivity is more efficient than relaxation of borehole temperatures in suppressing artifacts arising from the three dimensional effects we identify a range of constraints in which reasonable noise suppression and signal recovery are both achieved and then reprocess data from 22 canadian boreholes for which surface temperature histories had earlier been derived by ourselves and others our reprocessed results reveal a remarkably simple surface temperature history common to much of eastern canada this history comprises a recent warming interval commencing in the nineteenth century in which the surface temperature increased by some 1 4 c approximately 0 5 1 0 c of this increase was a recovery from a preceding cooler interval in which the temperature was below the long term mean the remainder of the increase represents warming that exceeds the long term mean

estimation of ground surface temperatures from borehole temperature data to infer past climatic changes from temperatures measured in boreholes one must obtain reliable estimates of ground surface temperature gst histories from these data this paper presents a method that uses a bayesian inverse technique to estimate the gst in the fourier frequency domain by assuming the a priori gst to be stationary with a prescribed standard deviation and a cutoff period the time series is constrained to be bounded and smooth because accounting for conductivity variations with depth is crucial to the estimation of gst a layered earth medium has been used for which the forward analytical solution of one dimensional heat conduction is available borehole data from flin flon and lac dufault in canada are inverted with this method the flin flon hole logged to a depth of 2900 m provides an opportunity to study long term gst variations and the estimated gst from this hole shows some effects of deglaciation at the end of pleistocene at lac dufault similar gsts were obtained independently from three holes ranging from 550 to 900 m and hence the results are considered more reliable in the lac dufault gsts there is a warm period centered about 1000 years bp and a cold period about 400 years b p confirming the presence of the little climatic optimum and the little ice age respectively the flin flon result does not show the little climatic optimum and the little ice age occurs about 100 200 years earlier however in both locations the gsts show another brief cold period around the turn of the century followed by rapid warming until 1940 1950 in good agreement with the trend of northern hemisphere surface air temperatures

earthquake damage history in israel and its close surrounding evaluation of spatial and temporal patterns abstract israel was hit by destructive earthquakes many times in the course of history to properly understand the hazard and support effective preparedness towards future earthquakes we examined the spatial and temporal distribution of the resulted damage we described in detail our systematic approach to searching the available literature collecting the data and screening the authenticity of that information we used gis geographic information system to map and evaluate the distribution of the damage and to search for recurring patterns overall it is found that 186 localities were hit 54 of them at least twice we also found that israel was affected by 4 17 8 and 2 damaging earthquakes that originated respectively from the southern central central northern and northern parts of the dead sea transform dst the temporal appearance of the northern earthquakes is clustered the central earthquakes are more regular in time whereas no damage from the north central and the central quakes with the exception of the year 363 earthquake seems to have occurred south of the dead sea region analyzing the distribution of the damage we realized that the number of the damage reports reflects only half of the incidents that actually happened attesting to incompleteness of the historical catalogue jerusalem is the most reported city with 14 entries followed by akko acre tiberias nablus and tyre with 8 7 7 and 6 reports respectively in general localities in the galilee and north of it suffered more severely than localities in central israel with the exception of nablus and the localities along the coastal plain of israel most probably due to local site effects for the sake of hazard management these observations should be considered for future planning and risk mitigation

young faults in the hula pull apart basin central dead sea transform abstract the geometry and nature of structural features inside the hula pull apart basin at the central dead sea transform are presented here two systems of n s left lateral strike slip faults are located on the east and west sides of the hula basin both fault systems are composed of several segments arranged in a right stepping en echelon pattern the northern end of each segment is bent northeastward and usually merges with the next segment elevated regions and small hills appear on the northern side of each bend the strike slip faults are oblique with both vertical and horizontal components the vertical component may be normal or reverse although the hula valley is subjected to general extension the studied structures indicate local compression inside the basin normal faults striking e w comprise the northern border of the hula basin age determination of displaced travertines and basalts along the faults indicates sub recent tectonic activity and suggests migration of normal faulting towards the inner part of the basin the youngest fault displaces travertine dated at 25 300 years

recurrence pattern of holocene earthquakes along the dead sea transform revealed by varve counting and radiocarbon dating of lacustrine sediments abstract a high resolution holocene seismic history of the dead sea transform dst is established from laminated sedimentary cores recovered at the shores of the dead sea radiocarbon dating and annual laminae counting yield excellent agreement between disturbed sedimentary structures identified as seismites and the historical earthquake record all recent and historical strong events of the area were identified including the major earthquakes of a d 1927 1837 1212 1033 749 and 31 b c the total of 53 seismites recognized along the entire holocene profile indicate varying recurrence intervals of seismic activity between a few and 1000 years with a conspicuous minimum rate at 2100 31 b c and a noticeable maximum during the past six to eight centuries most of the epicenters of the correlated earthquakes are situated very close to the dead sea within 150 km or up to 400 km north of it along the dst between 1000 b c and a d 1063 and from a d 1600 to recent time the epicenters are all located on the northern segment of the dst whereas prior to 1000 b c and between a d 1000 and 1600 they appear to scatter along several segments of the dst we establish how the local intensity exerts a control on the formation of seismites at historically estimated intensities greater than vii all well documented earthquakes are correlated whereas at intensities smaller than vi none are matching the periods with enhanced earthquake rate along the dst correlate with those along the north anatolian fault as opposed to the intervening east anatolian fault this may indicate some elastic coupling on plate boundary scale that may also underlie escape and extrusion tectonics typical of continental collision

upper cretaceous campanian phosphorites in jordan implications for the formation of a south tethyan phosphorite giant a record of sedimentary authigenic and biological processes are preserved within the upper cretaceous campanian alhisa phosphorite formation ap in central and northern jordan the ap formed near the eastern extremity of the south tethyan phosphorite province stpp a carbonate dominated upper cretaceous to eocene phosphorite giant that extends from colombia north africa to the middle east multidisciplinary research of the ap and associated cherts chalks and oyster buildups indicate that phosphatic strata formed on a highly productive storm dominated east west trending epeiric platform along the south tethyan margin the onset of phosphogenesis and the accumulation of economic phosphorite coincided with a rise in relative sea level that onlapped peritidal carbonates of the ajlun group pristine phosphates are associated with well developed micrite concretionary horizons and contain abundant non keeled spiral planktic foraminifera and a low diversity benthic assemblage of buliminacean foraminifera suggesting that pristine phosphates are a condensed facies and phosphogenesis was stimulated by the effects of a highly productive surface ocean and the suboxic diagenesis of sedimentary organic matter the bulk sediment composition and absence of fe bearing authigenic phases such as glauconite pyrite including pyrite molds siderite and goethite within pristine phosphates suggests that deposition and authigenesis occurred under conditions of detrital starvation and that iron pumping played a minimal role in phosphogenesis authigenic precipitation of phosphate occurred in a broad array of sedimentary environments herein termed a phosphorite nursery that spanned the entire platform this is a non uniformitarian phenomenon reflecting precipitation of sedimentary apatite across a wide depositional spectrum in a variety of depositional settings wherever the conditions were suitable for phosphogenesis sedimentologic data indicate that pristine phosphates were concentrated into phosphatic grainstones through storm wave winnowing and storm generated shelf parallel geostrophic currents economic phosphorites formed through the amalgamation of storm induced event beds stratigraphic packaging of phosphatic strata indicates that temporal variations in storm frequency were a prerequisite for the formation of economic phosphorite syndepositional phosphogenesis reworking and amalgamation to form phosphorites contrasts sharply with the principles of baturin cycling a transgressive systems tract coupled with high surface productivity created detritally starved settings favourable for phosphogenesis storm reworking of pristine

estimating slope stability reduction due to rain infiltration mounding rainwater can infiltrate into slopes and earth dams given sufficient infiltrating rainfall intensity frequency and time the phreatic line within the slope or dam will mound above its otherwise steady state position such a mound will increase downslope seepage and reduce downslope stability this paper develops an approximate method for solving this transient seepage mounding problem and the resulting reduction in stability it shows the following variables will reduce stability increased rainfall intensity and duration decreasing permeability especially over the 10 2 10 4 mm s range and its anisotropy increasing the slope cotangent decreasing the depth to an impermeable underlayer or increasing the depth to a permeable underlayer increasing size and effective porosity has only a time effect in special circumstances the mounding effect can reduce slope stability by 50 and the paper includes a slope case history example

evidence for 830 years of seismic quiescence from palaeoseismology archaeoseismology and historical seismicity along the dead sea fault in syria an edited version of this paper was published in earth and planetary science letters by elsevier science elsevier science retains the copyright to this paper copyright 2003 see also http dx doi org 10 1016 s0012 821x 03 00144 4 http atlas geo cornell edu deadsea publications meghraoui2003 epsl htm

the palaeoecology of the callovian and oxfordian strata of majdal shams syria and its implications for levantine palaeogeography and tectonics abstract palaeoecological study of fossils from jurassic strata of majdal shams syria reveals a deepening and shallowing sequence of water conditions from callovian to tithonian time maximum water depth apparently occurred in the lower oxfordian where both fossils and lithology are typical of the deeper water parts of the tethys the contrast with very shallow facies nearby in lebanon is very marked the only acceptable palaeogeographic reconstruction of this region is obtained by accepting the widely proposed post jurassic 110 km sinistral strike slip movement on the dead sea fault on this reconstruction the majdal shams region becomes an extension of the basinal tethys along the nw se trending kishon jezreel graben this is strong evidence for tensional ne sw movements in the levantine area long before the miocene opening of the red sea

ground penetrating radar investigation of active faults along the dead sea transform and implications for seismic hazards within the city of aqaba jordan abstract ground penetrating radar gpr was used in an effort to locate a major active fault that traverses aqaba city jordan measurements over an exposed trenched cross fault outside of the city identify a radar signature consisting of linear events and horizontal offset flexured reflectors both showing a geometric correlation with two known faults at a control site the asymmetric linear events are consistent with dipping planar reflectors matching the known direction of dip of the faults however other observations regarding this radar signature render the mechanism generating these events more complex and uncertain gpr measurements in aqaba city were limited to vacant lots seven gpr profiles were conducted approximately perpendicular to the assumed strike of the fault zone based on regional geological evidence a radar response very similar to that obtained over the cross fault was observed on five of the profiles in aqaba city although the response is weaker than that obtained at the control site the positions of the identified responses form a near straight line with a strike of 45 although subsurface verification of the fault by trenching within the city is needed the geophysical evidence for fault zone location is strong the location of the interpreted fault zone relative to emergency services military bases commercial properties and residential areas is defined to within a few meters this study has significant implications for seismic hazard analysis in this tectonically active and heavily populated region

continuum calculations of continental deformation in transcurrent environments a thin viscous sheet approximation is used to investigate continental deformation near a strike slip boundary the vertically averaged velocity field is calculated for a medium characterized by a power law rheology with stress exponent n driving stresses include those applied along boundaries of the sheet and those arising from buoyancy forces related to lateral differences in crustal thickness calculations are performed with either velocity or stress prescribed on the transcurrent boundary exact and approximate analytic solutions for a region with a sinusoidal strike slip boundary condition are compared with solutions for more geologically relevant boundary conditions obtained using a finite element technique the across strike length scale of the deformation is approximately 1 4 n 1 2 times the dominant wavelength of the imposed strike slip boundary condition for both the analytic and the numerical solutions this result is consistent with length scales observed in continental regions of large scale transcurrent faulting an approximate linear relationship between displacement and rotation is found that depends only on the deformation length scale and the rheology calculated displacements finite rotations and distribution of crustal thicknesses are consistent with those observed in the region of the pacific north america plate boundary in california

sources of the large a d 1202 and 1759 near east earthquakes the sources of the may 1202 and november 1759 m 7 5 near east earthquakes remain controversial because their macroseismal areas coincide straddling subparallel active faults in the lebanese restraining bend paleoseismic trenching in the yammouneh basin yields unambiguous evidence both for slip on the yammou neh fault in the twelfth thirteenth centuries and for the lack of a posterior event this conclusion is supported by comparing the freshest visible fault scarps which imply more recent slip on the r chaiya serghaya system than on the yammouneh fault our results suggest that the recurrence of an a d 1202 type earthquake might be due this century as part of a sequence similar to that of a d 1033 1202 possibly heralded by the occurrence of the 1995 mw 7 3 aqaba earthquake the seismic behavior of the levant fault might thus be characterized by millennial periods of quiescence separated by clusters of large earthquakes

active tectonics of the yizre el valley israel using high resolution seismic reflection data abstract we present a series of high resolution seismic reflection lines across the yizre el valley which is the largest active depression in israel off the main trend of the dead sea rift the new seismic reflection data is of excellent quality and shows that the valley is dissected into numerous small blocks separated by active faults the yizre el valley is found to consist of a series of half grabens rather than a single half graben or a symmetrical graben the faults are generally vertical and appear to have a dominant strike slip component but some dip slip is also evident a marked zone of compression near megido is associated with the intersection of the two largest faults in the valley the carmel fault and the gideon fault variable trend of the faults reflects the complexity of the local geology along the boundary between the wide nw se trending farah carmel fault zone and the e w trending basins and ranges in the lower galilee this tectonic complexity is likely to result from a highly variable stress pattern modified by the structures inside it normal faulting in the valley occurred at an early stage of its development as a tectonic depression however strike slip motion on the carmel fault and possibly also on some of the other faults appears to have started together with the onset of normal faulting earthquake hazard in the area appears to be uniform as faults are distributed throughout the yizre el valley