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

the role of volcanic eruptions in blocking the drainage leading to the dead sea formation the shrinkage of the lisan lake ll to form the recent dead sea ds was mainly a result of the reduction of the catchment area from around 157 000 km2 during late pleistocene to 43 000 km2 presently the reduction in the catchment area resulted from the eruption and spread of the basalt flows of jabal arab druz jad which together with the resulting deposition of thick rock debris and gravels occupied the drainage system the filling of the pre basalt drainage system which used to feed the dead sea with basalts and alluvial sediments blocked the inflows from reaching the dead sea local base levels along the basalt flow boarders such as azraq oasis sirhan basin and damascus oasis and numerous pools and mud flats were created

3 d density modelling of underground structures and spatial distribution of salt diapirism in the dead sea basin a new compilation of bouguer gravity data stemming from airborne shipborne and terrestrial data set in the entire dead sea basin dsb was reinterpreted by applying 3 d density modelling that incorporated independent information on other geophysical researches allowing for regional and residual filtering in the gravity field carrying out curvature analysis and euler deconvolution of the combined gravity field 3 d density modelling enables us to detailed resolution of upper crustal structures from the southern to the northern subbasin below the saline dead sea 3 d gravity modelling led to the identification of three salt structures which are found beneath the sedom area the lisan peninsula and the dead sea in the vicinity of the western margin of the dead sea a salt diapir segment with a thickness of about 4 km has been identified at a top depth of about 2 km which has not been recognised by any other geophysical interpretations the thickness of the sedimentary infill overlying the basement in the dsb decreases from 14 km in the vicinity of the lisan peninsula to 8 km in the northern and the southern subbasins large negative gravity anomalies lower than 100 x 10 5 m s 2 observed in the dsb correspond with the spatial distribution of salt diapirism with an average density of 2 100 kg m 3 the shallower microearthquakes registered in the dsb are related to the movement of salt diapir in the dsb

depth dependent crustal scattering attenuation revealed using single or few events in south korea few studies have been conducted on the variance of scattering graphic 1 and intrinsic attenuation graphic 2 with depth in the crust furthermore these values routinely estimated using multiple lapse time window analysis mltwa were seriously affected by different earthquake depths based on earthquakes recorded by dense seismic networks in south korea we used the mltwa method on single or small clusters of events with similar depths the depths of 54 earthquakes relocated using seven velocity models provide a typical seismogenic layer with the brittle plastic transition bpt depth at 11 km which correlated well with the seismicity of korea the depth was also used for the theoretical model based on the direct simulation monte carlo method as the result of mltwa events with shallow focal depths exhibit higher graphic 3 correlated with dense scatter whereas those with deeper focal depths exhibit lower graphic 4 this depth dependency of the graphic 5 value is indicated by the significant difference between the upper and lower parts of the bpt depth in the seismogenic layer we also found that graphic 6 values do not show depth dependency whereas graphic 7 values do thus this study demonstrates for the first time that the crustal depth dependency of total graphic 8 attenuation originates from graphic 9 rather than from graphic 10 the approach using single or few events may be helpful for a regional study of graphic 11 and graphic 12 in seismically inactive regions for which insufficient data exist and may provide insight into the seismogenic layer related to potential seismic hazards online material tables of residuals and range of multiple lapse time window analysis mltwa parameters and q 1 values for studied events 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif 4 embed inline graphic 4 gif 5 embed inline graphic 5 gif 6 embed inline graphic 6 gif 7 embed inline graphic 7 gif 8 embed inline graphic 8 gif 9 embed inline graphic 9 gif 10 embed inline graphic 10 gif 11 embed inline graphic 11 gif 12 embed inline graphic 12 gif

separation of depth dependent intrinsic and scattering seismic attenuation in the northeastern sector of the italian peninsula summary we investigated the intrinsic dissipation and scattering properties of the lithosphere under the friuli region northeastern italy using two hypotheses i a uniform earth model and ii two reasonable non uniform layered crustal models for case i we measured the coda q and used the multiple lapse time window analysis mltwa technique to obtain separate estimates of intrinsic absorption and scattering attenuation results for the uniform earth model show that the lithosphere in northeastern italy is characterized by a low scattering attenuation small scattering q inverse q 1 and by a relatively high intrinsic attenuation high intrinsic q inverse q 1 a comparison between the investigated region and other areas around the world shows that both q 1 and q 1 for the friuli region are among the lowest values ever measured with the exception of the southern apennines which has the lowest measured q 1 for case ii numerical simulation of the energy envelopes was performed using two layered earth models where the values of the intrinsic and scattering attenuation coefficients are both within reasonable ranges when compared with the geological information the theoretical envelopes calculated for the homogeneous model give a good fit to the synthetic envelopes calculated for the layered models the best fit is obtained for scattering attenuation coefficients of the uniform model always greater than those of the layered model the main result is consequently that scattering q 1 obtained using the mltwa under the assumption of a uniform medium is overestimated on average by a factor 2 finally coda q 1 appears to be closer to the total q 1 than to the intrinsic q 1 a spredicted

localisation and temporal variability of groundwater discharge into the dead sea using thermal satellite data the semi arid region of the dead sea heavily relies on groundwater resources this dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management yet information on groundwater discharge as one main component for a sustainable management varies significantly in this area moreover discharge locations volume and temporal variability are still only partly known a multi temporal thermal satellite approach is applied to localise and semi quantitatively assess groundwater discharge along the entire coastline the authors use 100 landsat etm band 6 2 data spanning the years between 2000 and 2011 in the first instance raw data are transformed to sea surface temperature sst to account for groundwater intermittency and to provide a seasonally independent data set t maximum sst range per pixel within biennial periods is calculated subsequently groundwater affected areas gaa are characterised by t 10 c this allows the exact identification of 37 discharge locations clusters along the entire dead sea coast which spatially correspond to available in situ discharge observations tracking the gaa extents as a direct indicator of groundwater discharge volume over time reveals 1 a temporal variability correspondence between gaa extents and recharge amounts 2 the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge 3 a certain variability in discharge locations as a consequence of the dead sea level drop and finally 4 the assumed flushing effect of old dead sea brines from the sedimentary body to have occurred at least during the two series of 2000 2001 and 2010 2011

postdepositional losses of methane sulfonate nitrate and chloride at the european project for ice coring in antarctica deep drilling site in dronning maud land antarctica nitrate and typically 51 20 of msawere lost while for chloride no significant depletion could be observed in firn older than one year assuming a first order exponential decay rate the characteristic e folding time for msais 6 4 3 years and 19 6 years for nitrate it turns out that for nitrate and msathe typical mean concentrations representative for the last 100 years were reached after 5 4 and 6 5 years respectively indicating that beneath a depth of around 1 2 1 4 m postdepositional losses can be neglected in the area of investigation only msaconcentrations and postdepositional losses showed a distinct dependence on snow accumulation rate consequently msa concentrations archived at this site should be significantly dependent on the variability of annual snow accumulation and we recommend a corresponding correction with a simple approach we estimated the partial pressure of the free acids msa hno3 and hcl on the basis of henry s law assuming that ionic impurities of the bulk ice matrix are localized in a quasi brine layer qbl in contrast to measurements this approach predicts a nearly complete loss of msa n o3 and cl index terms 0322 atmospheric composition and structure constituent sources and sinks 0330 atmospheric composition and structure geochemical cycles 0365 atmospheric composition and structure troposphere composition and chemistry 1827 hydrology glaciology 1863 1863 hydrology snow and ice 1827 keywords postdepositional loss snow chemistry methane sulfonate

ice age paleotopography a gravitationally self consistent theory of postglacial relative sea level change is used to infer the variation of surface ice and water cover since the last glacial maximum lgm the results show that lgm ice volume was approximately 35 percent lower than suggested by the climap reconstruction and the maximum heights of the main laurentian and fennoscandian ice complexes are inferred to have been commensurately lower with respect to sea level use of these ice age boundary conditions in atmospheric general circulation models will yield climates that differ significantly from those previously inferred on the basis of the climap data set

ice age terrestrial carbon changes revisited n shackleton 1977 first proposed that changes in the marine 13 c record 13 c could be used to infer ice age changes in carbon storage on land the previously published best estimate from the marine record is equivalent to about 490 gt 0 32 13 c however adams et al 1990 utilized a pollen database to estimate a 1350 gt change in carbon storage which would cause a 13 c of about 0 90 the nearly trillion ton difference in estimates amounts to almost half of the total carbon stored on land to address the nature of this discrepancy i have reexamined the terrestrial carbon record based on a new pollen database compiled by r webb and the cooperative holocene mapping project cohmap group i estimate about 750 1050 gt glacial interglacial change in terrestrial carbon storage with the range reflecting uncertainties in carbon storage values for different biomes additional uncertainties apply to rainforest and wetland extent and presence of c4 plants which have a significantly different isotopic signature than c3 plants although some scenarios overlap a new estimate of carbon storage based on the oceanic 13 c record revised to 0 40 and 610 gt most estimates seem to fall outside the envelope of uncertainty in the marine record several possible explanations for this gap involve 1 a missing sink may be involved in land sea carbon exchange e g continental slopes 2 the geochemistry of the exchange process is not understood 3 carbon storage by biome may have changed under ice age boundary conditions or 4 the standard interpretation of whole ocean changes in the marine 13 c record requires reevaluation this latter conclusion receives some support from comparison of the 13 c records for 18 o stages 2 and 6 for the stage 6 glacial the 13 c changes are 50 60 larger than for the stage 2 glacial yet implications of increased aridity are not supported by longterm trends in atmospheric dust loading to summarize the above analysis implies that despite the uncertainties remaining in estimates of terrestrial carbon storage changes a case can be made that our understanding of the transfer process is incomplete and that the eventual explanation may require clarification of factors affecting the marine 13 c record

human induced geological hazards along the dead sea coast the dead sea is a terminal lake whose level is currently dropping at a rate of about 1 m per year due to the over exploitation of all its tributaries the lowering started about four decades ago but geological hazards appeared more and more frequently from the end of the 1980s the water level lowering is matched by a parallel groundwater level drop which results in an increasing intensity of underground and surface water flow the diagonal interface between the dead sea brine and the fresh groundwater is pushed downwards and seawards nowadays sinkholes subsidence landslides and reactivated salt karsts affect wide coastal segments until now mainly infrastructures were damaged and few people animals were injured but the ongoing development of tourism in this very attractive situation will increase the risk if precautionary measures are not included in the development plans this paper discusses the main observations made all around the dead sea and shed a light on the differences between the geological hazards of the western shore israel palestinian authority and the eastern shore jordan it is the first attempt to bring together an overview of the human induced geological hazards encountered along the dead sea coast

salt dissolution and sinkhole formation along the dead sea shore 1 the formation of sinkholes at the dead sea area reflects subsurface cavities formed by salt dissolution this dissolution is related to the recession of the dead sea the groundwater level and the fresh saline water interface along the shore decline at a similar rate to the rate of the dead sea recession and brines that used to occupy layers below this interface are flushed out by freshwater our finite element modeling shows that dissolution of this salt layer is a plausible mechanism to explain the rapid creation of subsurface holes that collapse and form sinkholes the positive feedback between the rate of flow the rate of chemical reaction and the change in permeability accelerates the dissolution processes and might result in reactive infiltration instability which is manifested in fingers of cavities into which fluid is channeled and salt is dissolved the spacing between the sinkholes and the rate of their creation is controlled by several factors including properties of lineaments faults incoming groundwater flux the salinity of the incoming groundwater the rate of dissolution the effective specific surface area the permeability of the salt and clay layers the permeability porosity relation the dispersivity and the thickness of the layers we show that the creation of sinkholes occurs only under specific conditions these conditions must cause an unstable dissolution front which then causes formation of cavities and eventually sinkholes the simulations which utilized the best estimated parameters of the studied area yield results that are similar to those exhibited in the field

structural control on drainage network and catchment area geomorphology in the dead sea area an evaluation using remote sensing and geographic information systems in the wadi zerka ma in catchment area jordan the geology of jordan is characterized by fault systems with three major trends 1 nw se the oldest 2 wnw ese and 3 nnw sse the youngest the drainage network of the wadi zerka ma in catchment area located in the middle of the dead sea rift parallels these structural orientations a regional transtensive fault with embedded normal faults bounds the lower and middle part of the catchment area the topographic profile of the zerka ma in river exhibits two major knickpoints where it crosses two major embedded normal faults the second major knickpoint developed as a result of the dramatic lowering of the lisan lake water level a lake that pre dates the dead sea the decreased water level triggered river incision into the clastic sandstone units of wadi zerka ma in we performed a morphotectonic analysis study to investigate how the rock structures control the drainage network and the catchment area geomorphology according to the transverse topographic symmetry factor t the catchment area is highly asymmetric the major basin asymmetry trend is se oriented parallel to the oldest set of fault systems the catchment area displays a convex hypsometric curve indicating a very recent stage in the geomorphologic cycle our study indicates that the lisan lake catchment area shrinkage and structures growth controlled and shaped the wadi zerka ma in catchment area geomorphology the combined use of a geographic information system gis and remote sensing was shown to be very efficient in unraveling the evolution of the drainage network and catchment area geomorphology

why large earthquakes do not nucleate at shallow depths although by definition tectonic earthquakes may nucleate anywhere within the seismogenic layer in almost all cases those earthquakes that become large nucleate near the base of the seismogenic layer because frictional strength and stress drop should increase with depth and in situ stress measurements suggest that the ambient stress increases with depth we have examined spontaneous rupture models with gradients of both average stress drop and average strength relative to ambient stress to determine whether this explains the observed phenomena we report here that ruptures that are nucleated with in the low stress drop shallow regions of the model are inhibited from propagating but those that are nucleated within the high stress drop regions can propagate over the entire fault plane

potential and limitations of marine and ice core sea ice proxies an example from the indian ocean sector diatom assemblages in marine cores and sea salt deposition fluxes in ice cores have been used as sea ice proxies in the southern hemisphere here a marine and an ice core proxy record for the indian ocean covering the last two glacial cycles are compared in order to illustrate their potential and limitations the marine core was extracted in a location completely ice free under present day conditions and therefore was unable to record changes to the recent sea ice extent similarly no sea ice was recorded at that location during the previous interglacial period during the last glacial period however the site was seasonally covered by sea ice and the diatom assemblages allowed an estimation of average seasonal sea ice presence the ice core data originated from the east antarctic plateau the marine sodium present in the ice core was used as a proxy of the sea ice coverage and on average a larger sea ice surface led to an increased sea salt aerosol flux seen e g at the last glacial inception however the response of the sea salt flux to increasing sea ice extent diminished during peak glacial conditions when only minimal variability was recorded in the ice core record a first order approximation is used to take this non linear response of the ice core sea ice proxy into account based on the ice core proxy record sea ice extent was reduced considerably during the warm episodes of the previous two interglacial periods compared to modern sea ice extent in particular during the peak warmth of the last interglacial the ice core proxy also showed a very strong precessional variability pronounced spectral peak at 23 ka period over the past 240 ka the advantage of combining the two proxy records lies in the complementary nature of their response while the ice core proxy showed limited sensitivity during full glacial conditions the marine proxy recorded the seasonal sea ice coverage once the sea ice retreated south of the location of the marine core the ice core proxy responded to changes in sea ice extent a composite of marine and ice core records may thus provide a data basis for a more detailed reconstruction of sea ice around antarctica over the last few glacial interglacial cycles

reappraisal of antarctic seasonal sea ice at the last glacial maximum we used modern analog technique applied to antarctic diatoms to quantitatively reconstruct seasonal sea ice extent at the last glacial maximum winter maximum sea ice limit occurred around 48 s in the atlantic and western indian sectors around 55 s in the eastern indian and western pacific sectors and around 58 60 s in the eastern pacific sector of the southern ocean summer maximum sea ice extents during the last ice age and today are similar which contradicts climap s findings this implies a reduced summer albedo feedback of the southern hemisphere and a greater transfer of heat and moisture from the ocean to the atmosphere than shown by previous qualitative studies

southern ocean sea ice extent productivity and iron flux over the past eight glacial cycles sea ice and dust flux increased greatly in the southern ocean during the last glacial period palaeorecords provide contradictory evidence about marine productivity in this region but beyond one glacial cycle data were sparse here we present continuous chemical proxy data spanning the last eight glacial cycles 740 000 years from the dome c antarctic ice core these data constrain winter sea ice extent in the indian ocean southern ocean biogenic productivity and patagonian climatic conditions we found that maximum sea ice extent is closely tied to antarctic temperature on multi millennial timescales but less so on shorter timescales biological dimethylsulphide emissions south of the polar front seem to have changed little with climate suggesting that sulphur compounds were not active in climate regulation we observe large glacial interglacial contrasts in iron deposition which we infer reflects strongly changing patagonian conditions during glacial terminations changes in patagonia apparently preceded sea ice reduction indicating that multiple mechanisms may be responsible for different phases of co2 increase during glacial terminations we observe no changes in internal climatic feedbacks that could have caused the change in amplitude of antarctic temperature variations observed 440 000 years ago

ammonium and non sea salt sulfate in the epica ice cores as indicator of biological activity in the southern ocean sulfate so42 and ammonium nh4 flux records over the last 150 000 years from both antarctic epica ice cores european project for ice coring in antarctica are presented the ice core record from dome c is influenced by the indian sector of the southern ocean so whereas dronning maud land is facing the atlantic sector generally they reflect the past atmospheric aerosol load and thus potentially reveal the fingerprint of marine biogenic sources from the so the most important feature of both the nssso 4 2 as well as nh4 flux records is the absence of any significant glacial cycles in contrary to the distinct transitions for mineral dust and sea salt aerosol over the last 150 000 years this finding challenges the iron fertilization hypothesis on long time scales as the significant changes in dust e g from the last glacial maximum toward the holocene have neither an impact on nssso 4 2 nor on nh4 fluxes found in interior antarctica the inter site correlation of both species is weak r 2 0 42 for the nssso 4 2 flux and r 2 0 12 for the nh4 flux respectively emphasizing the local source characteristics of biogenic aerosol from the so millennial variability in nh4 and nssso 4 2 is within the uncertainty of our flux estimates correlation with mineral dust and sea ice derived sodium shows only a very weak influence of dust deposition on those insignificant changes in nssso 4 2 flux for the atlantic sector of the southern ocean but also small transport changes or terrigeneous sulfate contributions may contribute to those variations at edml c 2009 elsevier ltd all rights reserved

groundwater chemistry of strike slip faulted aquifers the case study of wadi zerka ma in aquifers north east of the dead sea wadi zerka ma in catchment area is located to the north east of the dead sea it has two types of aquifers a an upper unconfined aquifer and b a lower confined aquifer the two aquifers are separated by a marl aquiclude a major strike slip fault passes perpendicularly through the two aquifers and the aquiclude layer with embedded normal faults the aim of the study was to specify the effect of the major strike slip fault on the groundwater chemistry the spatial variability of the hydrochemical compositions and physiochemical parameters of the groundwater were investigated it was found that the embedded normal faults of the strike slip fault form conduits that allow groundwater to flow from the lower aquifer to the upper aquifer resulting in mixed groundwater the ratio of mixing was estimated to be 94 groundwater from the upper aquifer and 6 from the lower aquifer since groundwater in the lower aquifer is around three times more saline than the upper aquifer water mixing into the upper water aquifer generates a salinity hazard

migration of methane sulphonate in antarctic firn and ice we investigate the seasonal relationship of the sulphur bearing anions methane sulphonate msa and non sea salt sulphate nssso42 in sections of firn and ice cores from the antarctic peninsula and weddell sea region of antarctica in cores from dolleman island and berkner island msa has clearly migrated from the summer snow layer where it is initially deposited to become concentrated in the winter layer a similar behavior is evident in a core from the dyer plateau though in deeper layers cores from gomez nunatak and beethoven peninsula show little evidence of relocation of msa though migration at greater depth in the ice sheet cannot be ruled out in contrast in all these cores non sea salt sulphate remains in the summer layer from comparisons between the ice core characteristics and the migration behavior at these sites we conclude that the movement of msa does not occur via percolation and refreezing of meltwater simple concentration driven diffusion is also not a factor as the msa peaks are sharp in the winter layer the data presented indicate that the movement of msa in firn is likely to be linked to the concentration of other ionic species in the snowpack and to the snow accumulation rate a possible mechanism for the migration of msa in the snowpack is via an initial diffusion in the liquid or vapor phase which is halted by trapping in the winter layer when the msa forms a salt with a cation

sustainable development and anthropogenic induced geomorphic hazards in subsiding areas in many areas of the world subsidence related to the lowering of the water table is modifying the landscape and provoking costly environmental hazards this article is protected by copyright all rights reserved we consider the dead sea the earth s lowest lake as a model its water level was 395 m bmsl in the 1960s due to water diversions in the catchment area as of 2016 the level has dropped to about 430 m bmsl here as in other parts of the anthropocene world from china to iran to turkey to canada and the united states consequences of human interventions are rapidly modifying the environment aggressive geomorphic processes leading to accelerated degradations are taking place and affecting landforms and infrastructures this article is protected by copyright all rights reserved in tectonic terms the lake is a pull apart basin resulting from the motion of the dead sea transform fault since the 1960s a slice of brine of about 35 km3 had been lost the water table is dropping more rapidly in the lake than in the coastal zone creating an ever increasing head difference consequently groundwater moves towards the sea to compensate for the imbalance provoking the reactivation of the area s paleo channels with subsidence sinkholes and landslides this article is protected by copyright all rights reserved since the 1980s industrial touristic infrastructure has covered newly emerging lands in geomorphic hazards prone areas of the coastal zone this article is protected by copyright all rights reserved time series analysis of high to very high resolution visible radar satellite images acquired from the 1970s to present revealed major landscape evolution such dynamic systems prevailing in the last decades permitted the study of human environment interactions to help minimizing their effects this article is protected by copyright all rights reserved major deformations of an industrial dike were analysed and quantified the results underline the necessity in the anthropocene of careful analysis of relevant data sources acquired before and during subsidence particularly in karst topography zones and prior to the development of major human activities in economically appealing environments around the world this article is protected by copyright all rights reserved

karst system developed in salt layers of the lisan peninsula dead sea jordan the lisan peninsula jordan is a massive salt layer accumulated in the inner part of the dead sea s precursory lakes this tongue shaped emergent land results in a salt diapir uplifted in the dead sea strike slip regional stress field and modified by the water level fluctuations of the last lake during the holocene these two elements associated with dissolution caused by rainfall and groundwater circulation resulted in an authentic karst system since the 1960s the dead sea lowering of 80 cm to 1 m per year caused costly damages to the industrial plant set up on the peninsula the lisan karst system is described in this article and the components of the present dynamic setting clarified

crustal velocity structure across the southern korean peninsula from seismic refraction survey 1 the first crustal scale controlled source seismic refraction experiment in the southern korean peninsula kcrust2002 was carried out along a 300 km long profile across this peninsula in december 2002 iterative processing and modeling produced a laterally varying layered crustal velocity model the crust is thickest 34 km below the okcheon fold belt in the middle of the transect and thinnest 28 km at the eastern end where the cretaceous gyeongsang basin is characterized by 5 km of low velocity material that constitutes the upper crust the p velocities in upper and lower crust range from 5 4 to 6 0 km s and from 6 4 to 6 7 km s respectively the average crustal poisson s ratio is found to be 0 25 0 27 vp vs 1 73 1 78 along the profile a mid crustal velocity discontinuity is recognized in the northwestern part of the transect the underlying mantle has velocities in the range of 7 9 8 1 km s

intrinsic and scattering attenuation in the crust of the abu dabbab area in the eastern desert of egypt abstract fifty five microearthquakes recorded by a digital temporary seismic network in the abu dabbab area in the eastern desert of egypt were used to estimate the direct s wave q coda q c intrinsic q i and scattering quality factors q s sato s sato h 1977 single scattering assumption was used to fit the amplitude envelopes of the coda at seven central frequency bands 1 5 3 6 9 12 18 and 24 hz obtaining a q c varying with frequency as generally observed in tectonically active areas lapse time dependence was also studied for the area with the coda waves analyzed at window lengths ranging from 10 to 40 s starting from the onset of the s wave arrival the direct s wave q was estimated using the coda normalization method aki k 1980a the frequency dependence of q was investigated for the direct s waves and coda waves results show a low quality factor and a high frequency parameter indicating that the upper lithosphere of the abu dabbab area is seismically active and heterogeneous using the independent estimates of q c and q the intrinsic quality factor q i was separated from the scattering quality factor the results suggest that intrinsic dissipation plays a predominant role with respect to scattering phenomena in the area the obtained q values seem closer to those reported by analyzing volcano tectonic earthquakes this finding reflects that the cause of abu dabbab earthquake swarms might be igneous activity where the magma is ascending through joints or serpentinized joints that are dewatering

deep fault plane revealed by high precision locations of early aftershocks following the 12 september 2016 ml 5 8 gyeongju korea earthquake an m l 5 8 earthquake which is large for a stable continental region occurred in southeastern korea on 12 september 2016 ten days of data from a temporary seismic network deployed immediately after the mainshock are combined with data from permanent seismic stations to determine high precision locations of early aftershocks to reveal the geometry of the causative structure at depth well constrained relative earthquake hypocenters and focal mechanisms are used to define the subsurface fault plane with a strike of similar to n28 degrees e and dip of similar to 78 degrees to the east southeast this fault plane extends from 12 to 15 km depth and may have been responsible for most of the early earthquakes in the gyeongju earthquake sequence a pre existing weak zone in a strike slip duplex that formed from subsidiary riedel shears beneath the yangsan fault system may have been reactivated to nucleate the mainshock and aftershocks

the lowest place on earth is subsiding an insar interferometric synthetic aperture radar perspective since the early 1990s sinkholes and wide shallow subsidence features wssfs have become major problems along the dead sea shores in israel and jordan sinkholes are readily observed in the field but their locations and timing are unpredictable wssfs are often difficult to observe in the field however once identified they delineate zones of instability and increasing hazard in this study we identify characterize and measure rates of subsidence along the dead sea shores by the interferometric synthetic aperture radar insar technique we analyze 16 sar scenes acquired during the years 1992 to 1999 by the european remote sensing ers 1 and ers 2 satellites the interferograms span periods of between 2 and 71 months wssfs are observed in the lisan peninsula and along the dead sea shores in a variety of appearances including circular and elongate coastal depressions a few hundred meters to a few kilometers in length depressions in ancient alluvial fans and depressions along salt diapir margins phase differences measured in our interferograms correspond to subsidence rates generally in the range of 0 20 mm yr within the studied period with exceptional high rates that exceed 60 mm yr in two specific regions during the study period the level of the dead sea and of the associated ground water has dropped by 6 m this water level drop within an aquifer overlying fine grained marly layers would be expected to have caused aquifer system consolidation resulting in gradual subsidence comparison of our insar observations with calculations of the expected consolidation shows that in areas where marl layers are known to compose part of the upper 30 m of the profile estimated consolidation settlements are of the order of the measured subsidence our observations also show that in certain locations subsidence appears to be structurally controlled by faults seaward landslides and salt domes gradual subsidence is unlikely to be directly related to the sinkholes excluding the use of the wssfs features as predictable precursors to sinkhole formation

attenuation of multiphase surface waves in the basin and range province iii inversion for crustal anelasticity summary a combined inversion forward modelling procedure in which the frequency dependence of shear wave internal friction q 1 is allowed to vary with depth was developed and applied to selected rayleigh wave and lg attenuation data in the basin and range province of the south western united states both q and the frequency dependence of lg waves were used to constrain the models many models can explain rayleigh wave and lg data sets within their uncertainties but at 1 hz most have low values of q 50 80 in the upper 8 km of the crust rapidly increasing values to about 1000 at mid crustal depths and decreasing values at greater depths models which include a layer of higher q values 80 150 in the upper few kilometres of the crust overlying a region of lower q values cannot be precluded by the attenuation data of this study assuming that q varies with frequency as f models for which the frequency dependence is low 0 0 0 1 in the upper crust best explain the data of this study in the lower crust that frequency dependence is not well determined but the models which best explain both the fundamental mode and lg data and produce realistic models of q are characterized at 1 hz by high values of both q and its frequency dependence because of that frequency dependence q may be an order of magnitude lower at a period of 100 s 100 than it is at 1 s 1000 investigations of the effects of changing crustal velocity on values for lg q and its frequency dependence indicate that realistic velocity changes cause only small changes in those values and thus are inconsequential to our results the low q values and their constancy with frequency in the uppermost crust can be explained by fluid flow in a network of cracks in brittle rock increasing q with depth to 10 15 km can be explained by the closing of those cracks due to pressure and their enhanced healing with increasing temperature plastic flow at greater depths may contribute further to the dissipation of cracks and to further increases in q decreasing q values at greater depths can be explained as being the result of increasing temperature increasing content of partial melt enhanced dislocation motion or some combination of these effects

a tentative chronology for the epica dome concordia ice core a tentative age scale edc1 for the last 45 kyr is established for the new 788 m epica dome c ice core using a simple ice flow model the age of volcanic eruptions the end of the younger dryas event and the estimated depth and age of elevated 10be about 41 kyr ago were used to calibrate the model parameters the uncertainty of edc1 is estimated to 10 yr for 0 to 700 yr bp up to 200 yr back to 10 kyr bp and up to 2 kyr back to 41 kyr bp the age of the air in the bubbles is calculated with a firn densification model in the holocene the air is about 2000 yr younger than the ice and about 5500 yr during the last glacial maximum

sulfur cycle at last glacial maximum model results versus antarctic ice core data for the first time an atmospheric general circulation and sulfur chemistry model is used to simulate sulfur deposition in antarctica at the last glacial maximum lgm dimethylsulfide dms emitted by phytoplankton is the dominant source of atmospheric sulfur in antarctica once in the atmosphere it is oxidized into sulfur aerosols which are measured in ice cores such measurements allow for validating climate and chemistry models for glacial interglacial changes our glacial simulations test the effect of a recent re evaluation of glacial sea ice coverage on dms sources and sulfur aerosol deposition using the present day oceanic concentrations of dms the model reproduces observed glacial and interglacial sulfur concentrations in the ice this result suggests that climate change at the lgm did not greatly impact on dms production in the oceanic sectors where sulfur aerosols deposited in central east antarctica originate from

stratigraphic correlations between the european project for ice coring in antarctica epica dome c and vostok ice cores showing the relative variations of snow accumulation over the past 45 kyr 1 high resolution chemistry analysis and electrical measurements performed on two ice core records european project for ice coring in antarctica epica dome c and vostok spanning the last 45 kyr allow stratigraphic correlations by matching volcanic events several common events were identified along the two ice cores on the basis of acidity and sulphate spikes in snow layers timescales were matched through comparison with isotope d profiles and using the antarctic cold reversal acr minimum a 10be peak and a dust spike as temporal checkpoints ratios of relative snow accumulation at the two sites during the holocene in the glacial interglacial transition and in the last part of the glacial period were reconstructed by finding the best fit between dome c and vostok depths recording the same events after accounting for thinning of the layers as they are buried within the glacier the dome c vostok accumulation ratio expected to be roughly constant from the conventional accumulation temperature isotope approach is 1 12 for the glacial period but increases to as much as 1 44 for a large part of the holocene glaciological effects mainly related to the geographic origin of the vostok ice along the ridge b vostok axis can account for only a minor fraction of this change instead we argue that accumulation variability between the cores stems from differential changes in atmospheric circulation during these respective climatic periods at the two sites regional changes in atmospheric circulation are proposed with a negative anomaly in dome c a positive accumulation anomaly in vostok or a combination of both during glacial climate our approach may help to improve ice core dating by 1 revealing anomalies in accumulation rate estimation based on the classical thermodynamic method and 2 supporting the necessity to take into account contributions due to changes in atmospheric circulation processes

sensitivity of chemical species to climatic changes in the last 45 kyr as revealed by high resolution dome c east antarctica ice core analysis

frequency dependence of qlg and its relation to crustal anelasticity in the basin and range province the high observed frequency dependence of q for 1 hz lg waves f0 4 0 6 in the basin and range province can be explained by a frequency independent layered model of intrinsic q for shear waves q which has very low values in the upper crust and rapidly increasing values at greater depths by contrast earlier work in the eastern united states indicated q values in the upper crust which are high and which vary with frequency the q model which best explains reported values of qlg and its frequency dependence in the basin and range consists of an 8 km thick low q layer 60 or less overlying q values as high as 1000 or more at mid crustal depths this q distribution is best explained by an upper crust which contains fluids in interconnected cracks overlying a lower crust where higher lithostatic pressure has closed those cracks these results indicate that whereas the frequency dependence of q is an intrinsic property of crustal material the frequency dependence of qlg arises from both the intrinsic frequency dependence of crustal material and its layered structure a notation is suggested which distinguishes between the frequency dependence of qlg and q

p and s wave velocity model along crustal scale refraction and wide angle reflection profile in the southern korean peninsula abstract the onshore seismic experiment kcrt2004 explored the crustal velocity structure of the southern korean peninsula we present an interpretation of seismic data along this 340 km long nnw sse trending profile the crust was found to consist of three layers the upper middle and lower crust with p and s wave velocities ranging 5 50 to 6 95 km s and 2 82 to 3 91 km s respectively the average p wave velocity 6 26 km s and pn velocity 7 82 7 88 km s are lower than the worldwide average of continental crust moho depths are 29 0 34 9 km gradually thickening toward south the vp vs ratio of crustal material is estimated to be 1 73 0 249 for the upper and middle crust and the ratio increases with the depth in the lower crust the gyeonggi massif in the north of the profile has a lower vp vs ratio than other tectonic units the average crustal vp vs ratio of 1 74 0 253 is remarkably lower than the average value 1 78 0 27 for the bulk continental crust the low average crustal vp vs ratio is similar to that measured in eastern china the empirical analysis using both p wave velocity and vp vs ratio shows that the upper and middle crust is dominantly felsic and the lower crust is intermediate in composition the absence of the mafic material in the lower crust that is also found in eastern china contrasts with the generally accepted global model of the mafic lower crust

gcm simulations of the last glacial maximum surface climate of greenland and antarctica the lmdz variable grid gcm was used to simulate the last glacial maximum lgm 21 ky bp climate of greenland and antarctica at a spatial resolution of about 100 km the high spatial resolution allows to investigate the spatial variability of surface climate change signals and thus to address the question whether the sparse ice core data can be viewed as representative for the regional scale climate change this study addresses primarily surface climate parameters because these can be checked against the limited ice core record the changes are generally stronger for greenland than for antarctica as the imposed changes of the forcing boundary conditions e g sea surface temperatures are more important in the vicinity of greenland over greenland and to a limited extent also in antarctica the climate shows stronger changes in winter than in summer the model suggests that the linear relationship between the surface temperature and inversion strength is modified during the lgm the temperature dependency of the moisture holding capacity of the atmosphere alone cannot explain the strong reduction in snowfall over central greenland atmospheric circulation changes also play a crucial role changes in the high frequency variability of snowfall atmospheric pressure and temperature are investigated and possible consequences for the interpretation of ice core records are discussed using an objective cyclone tracking scheme the importance of changes of the atmospheric dynamics off the coasts of the ice sheets especially for the high frequency variability of surface climate parameters is illustrated the importance of the choice of the lgm ice sheet topography is illustrated for greenland where two different topographies have been used yielding results that differ quite strongly in certain nontrivial respects this means that the paleo topography is a significant source of uncertainty for the modelled paleoclimate the sensitivity of the greenland lgm climate to the prescribed sea surface conditions is examined by using two different lgm north atlantic data sets

lateral variation of the cutoff depth of shallow earthquakes beneath the japan islands and its implications for seismogenesis abstract we estimated the spatial distribution of the cut off depth of shallow seismicity beneath the japan islands based on data from a recently constructed nationwide dense seismic network in order to avoid the effect of heterogeneous seismic velocity structure we determined the 3d seismic velocity structure for the whole of japan which was then used to relocate the hypocenters the cut off depth was determined by calculating d90 the depth above which 90 of the earthquakes occur a spatial distribution of estimated d90 values shows a considerable lateral variation ranging from about 5 km to about 40 km the d90 s are deep along the pacific coast of eastern japan locally shallow d90 s extend along belt like stretches of volcanic areas heat flow is low along the pacific coast in eastern japan and high in the volcanic areas this indicates that the lateral variation of d90 s is formed mainly by lateral geotherm variation cooling by the subducting old very cold pacific plate may cause the deep d90 s along the pacific coast in eastern japan heating by magma supplied from the mantle wedge below is considered to be the main cause of the shallow d90 s in the volcanic areas magma and or aqueous fluids derived from solidified magma contribute not only to locally shallow d90 s but also to the weakening of ambient rocks in the lower crust resulting in stress concentrations in the upper crust just above them large shallow inland earthquakes tend to occur in such areas suggesting that a model of shallow earthquake generation applied to tohoku can be used in other areas in japan as well

depth dependent intrinsic and scattering seismic attenuation in north central italy summary in this study the attenuation mechanism of seismic wave energy in north central italy is estimated using low magnitude earthquake local data recorded at six stations managed by ingv most of the analysed events are located along the alpine chain in the zone of iseo and garda lakes while a minor part in the po valley the zone investigated is characterized by the occurrence of significantly intense earthquakes magnitude up to 6 6 the most recent occurred in 2004 close to the city of salo on the coast of the garda lake mw 5 0 due to the high population density and presence of industrial activity the investigated area is characterized by a high seismic risk first the ordinary multiple lapse time window analysis mltwa method is applied in the assumption of uniform velocity and scattering and the couple of b0 the seismic albedo and le 1 the extinction length inverse corresponding to the total attenuation coefficient is calculated in the frequency bands of 1 5 3 6 and 12 hz to retrieve more realistic estimates the obtained values of b0 and le 1 are corrected taking into account the effects of a depth dependent earth model consisting of an earth structure characterized by a transparent upper mantle and a heterogeneous crust we find that the corrected intrinsic and scattering attenuation parameters which are proportional to the inverse of the intrinsic scattering quality factors q 1i and q 1s are strongly frequency dependent with a prevalence of scattering attenuation over the intrinsic dissipation the corrected and uncorrected values of total q are in agreement with the total q values obtained with different approaches for the same area

structural control of sinkholes and subsidence hazards along the jordanian dead sea coast for about four decades the dead sea ds level and the surrounding water table has been dropping dramatically at least from the eighties the direct vicinity of the lisan peninsula lp jordan has been facing high rates of subsidence and sinkhole hazards between 2000 and 2002 the arab potash company apc lost two salt evaporation ponds resulting in a loss of 70 million in the fertile plain of ghor al haditha gah three deep and wide bowl shaped subsidence areas threaten human activities and infrastructures over the part of the lisan peninsula that emerged before the 1960s relict fossil sinkholes occurred everywhere whereas new collapses constantly appear in the southern area only in this paper we have integrated 15 years of field observations related to sinkholes and subsidence with interpretation of space borne radar interferometric outputs aerial photographs and satellite images this has helped to place hazardous areas in their geological context and to clarify them within the framework of the general tectonic setting of the area

monte carlo simulation of seismogram envelopes in scattering media the analysis of the seismogram coda envelopes of local and regional earthquakes is one of the most effective strategies for investigating the heterogeneous lithospheric structure characterized by the seismic scattering and attenuation in order to synthesize the coda envelope we introduce a numerical scheme called the direct simulation monte carlo method which has been used in the field of the kinetic theory of gases because of the simplicity of the algorithm the method has several advantages over previous methods in terms of the flexibility of the numerical calculation to incorporate various factors required to construct realistic seismogram envelopes on the basis of coda envelope simulations including multiple scattering we show that an increase of seismic velocity with depth severely affects the shape of the coda envelope the effects of ray bending due to the velocity increase at the moho and the reflection at the free surface are clearly found in the synthesized envelope for a shallow earthquake our simulation demonstrates that the amplitude of the envelope is magnified by stagnation of seismic energy at shallow depths due to the positive velocity gradient with depth because of this effect for an a priori assumption of a homogeneous velocity model the measurement of the scattering coefficient by conventional methods may be overestimated

frequency dependent attenuation in the crust the shear wave attenuation q l in the crust beneath the northeastern us and scandinavia is determined as a function of depth and frequency using theoretical modeling of complete waveforms in comparison with observed data to determine attenuation in the upper crust of the northeastern us short period 0 25 t 2 sec rg waves recorded by linear arrays of seismometers are used for scandinavia rg and lg waves are combined to extend the investigation into the deeper crust the combination of rg waves and short period t 1 0 sec lg waves makes it possible to determine attenuation as a function of depth and frequency in the crust parameterized as q qo f to match the observations theoretical models for three mechanisms that contribute to attenuation in the crust frequency independent anelastic qa 1 and frequency dependent fluid flow qf 1 and scattering qs 1 are considered the best fitting models require low q q0 100 in the shallow crust that increases with increasing frequency as f0 5 above 1 hz in the middle crust between about 2 to 10 km depth q is moderate 100 q0 500 with a frequency dependence of f1 in the lower crust the attenuation is very low q 500 and its frequency dependence is difficult to establish the low intrinsic q and the frequency dependence in the uppermost crust can be explained by fluid flow in fractures in the middle crust the frequency dependence suggests scattering the increase of q in the lower crust is most likely due to annealing of microcracks under pressure and temperature as observed in the laboratory

energy flux model of seismic coda separation of scattering and intrinsic attenuation a new model of seismic coda is presented based on the balance between the energy scattered from the direct wave and the energy in the seismic coda this energy flux model results in a simple formula for the amplitude and time decay of the seismic coda that explicitly differentiates between the scattering and intrinsic anelastic attenuation of the medium this formula is valid for both weak and strong scattering and implicitly includes multiple scattering the model is tested using synthetic seismograms produced in finite difference simulations of wave propagation through media with random spatial variations in seismic velocity some of the simulations also included intrinsic dissipation the energy flux model explains the coda decay and amplitude observed in the synthetics for random media with a wide range of scattering q in contrast the single scattering model commonly used in the analysis of microearthquake coda does not account for the gradual coda decay observed in the simulations for media with moderate or strong scattering attenuation scattering q less than or equal to 150 the simulations demonstrate that large differences in scattering attenuation cause only small changes in the coda decay rate as predicted by the energy flux model the coda decay rate is sensitive however more to the intrinsic q of the medium the ratio of the coda amplitude to the energy in the direct arrival is a measure of the scattering attenuation thus analysis of the decay rate and amplitude of the coda can in principle produce separate estimates for the scattering and intrinsic q values of the crust we analyze the coda from two earthquakes near anza california intrinsic q values determined from these seismograms using the energy flux model are comparable to coda q values found from the single scattering theory the results demonstrate that coda q values are at best measures of the intrinsic attenuation of the lithosphere and are unrelated to the scatteing q less

separation of intrinsic and scattering attenuation using single event source in south korea abstract simultaneous use of numerous events in the multiple lapse time window analysis mltwa method is the most effective way to obtain and values such simultaneous use of numerous events normally shows a large observational scatter which may be caused by different radiation pattern and focal depth of each earthquake and regional alteration of the local structure to avoid these scattering factors the current study attempted to use single event source as the input data in mltwa for south korea the direct simulation monte carlo dsmc method was used to simulate the observations which showed realistic results when the number of recorded stations was eight or more the obtained values of seismic albedo b 0 were less than 0 5 which were in accordance with the same in the previous results three envelopes constructed by combination of three regional values of at 1 hz produced regional variations of which the ones at high frequencies of and at low frequencies of were remarkable this result showing the local variation indicated an advantage of the study using single source event over the previous studies in south korea that involved extensively distributed data because dsmc was known to be applicable to 3d structure due to its simple algorithm the current study also tried to correct radiation pattern of the observations by inserting focal mechanism algorithm to the code of the dsmc method such insertion however generated extremely low values of because the geometrically shrunk receiver could not capture most of the scattered particles this receiver problem is most likely to be a major obstacle of the 3d study of dsmc in addition the significant depth effect of q 1 was identified for the prior mltwa studies resulting from different measurement range and focal depth

intrinsic and scattering attenuation of the mt fuji region japan summary mount fuji is the focus of intense study because of its potential hazard signaled by seismic geologic and historical activity based on extensive seismic data recorded in the vicinity of mt fuji coda quality factor q 1c using a single scattering model hypothesis and intrinsic and scattering quality factor q 1i and q 1s using the multiple lapse time window mltw method were measured to focus the study on the magmatic structure below mt fuji the data were separated into two groups a near fuji region of rays traversing an area with radius 5 km around the summit r 20 km this classification shows the largest discrepancy of q 1c at a range of sampling volumes corresponding to overlapped sampling depth of about 80 km further the spatial division shows significant difference of q 1i and q 1s at hypocentral distance of 80 km the large difference of q 1s in bandwidths 2 4 and 4 8 hz indicates lithospheric heterogeneity beneath mt fuji with a characteristic heterogeneity scale length of about 1 km the results have a small error range due to the large data sample showing that all q 1 values in the near fuji area are greater than those of the far fuji area and q 1i for both the near and far fuji areas is higher than q 1s at high frequencies the q 1i and q 1s values for far fuji are in the range of values for typical non volcanic areas the q 1i values of the near fuji area are lower than those of other volcanic areas considered where as values of q 1s are not the low q 1i for the volcanic region of near fuji suggests that the magmatic activity indicated by percent partial melt in the vicinity of mt fuji is not as active as hot spot volcanoes such as kilauea hawaii

the separation of intrinsic and scattering seismic attenuation in south korea abstract for the separation of intrinsic and scattering attenuation in south korea coda observations represented by the multiple lapse time windows method were numerically simulated using the direct simulation monte carlo method the simulation showed that the depth dependent velocity model separated by crust and mantle fit better than the uniform velocity model under a uniform attenuation assumption the and total in south korea represent the lowest values among current global measurements these low attenuation values can be explained by the inactive seismicity of south korea corresponding to those of the seismically stable area such as a shield

depth dependent seismicity and crustal heterogeneity in south korea abstract depth dependent seismicity has been suggested in the seismogenic layer which is divided into upper and lower layers by its seismicity boundary since large earthquakes tend to occur in the lower layer the structure of the seismogenic layer which includes the seismicity boundary provides important information for seismic hazard assessment using 107 land based earthquakes the structure of the seismogenic layer in south korea was studied with focal depth determination by identifying the minimum residuals between the observations and several models the same procedure was done for the depth relocation of 138 events associated with the gyeongju earthquake ml 5 8 the largest event in south korea in the last two centuries the geothermal temperature at the focal depth was also estimated for all earthquakes including the gyeongju earthquake cluster and the pohang earthquake ml 5 4 which caused more damage than did the gyeongju earthquake as observed in a large scale averaging of mainland china a 12 km seismicity boundary was suggested due to the frequent seismicity in the upper layer at 12 km depth at the gyeongju earthquake site the geothermal temperature reached 300 c and the occurrence of aftershocks was limited below that depth based on the rigorously estimated depth we separated the scattering attenuation qs 1 by a multiple lapse time window analysis using individual earthquakes and found higher and lower values for events in the upper and lower layers respectively this depth dependent observation suggests differences in heterogeneity between the upper and lower seismogenic layers and supports the hypothesis that the seismicity of a depth dependent seismogenic layer is related to cracks which diminish with depth our results suggest that the upper limit of the focal depth can be predicted from the depth of the seismicity boundary for normal large earthquakes

dead sea sinkholes an ever developing hazard sinkhole development along the western shore of the dead sea became a major concern in 1990 with the appearance of a series of holes 2 15 m diameter and up to 7 m deep in the newe zohar area one of these sinkholes below the asphalt surface of the main road along the western shore of the dead sea was opened by a passing bus repeated infilling and collapse of these holes indicated the extent of this ongoing process and the significance of this developing hazard since then sinkholes have developed in other areas including qalia ein samar ein gedi and mineral beach

spatial variation of coda wave attenuation in northwestern colombia summary one thousand seven hundred and eighty six vertical component short period observations of microearthquake codas from regional earthquakes recorded by 17 stations belonging to the national seismological network of colombia were used to estimate seismic wave attenuation in colombia local magnitudes range from 2 9 to 6 0 and only events occurring at hypocentral distances up to 255 km were considered for the analysis the frequencies of interest lay between 1 and 19 hz and the analysis was performed for each seismic station separately coda wave attenuation q 1 was estimated by means of a single scattering method whereas the separation of intrinsic absorption q 1 and scattering attenuation q 1 from total attenuation q 1 w as performed using a multiple lapse time window analysis based on the hypothesis of multiple isotropic scattering and uniform distribution of scatterers a regionalization of the estimated q0 qc at 1 hz values was performed and a contour map of seismic coda attenuation in colombia is presented where four zones with significant variations of attenuation related to different geological and tectonic characteristics can be observed the highest attenuation is linked to the central and western regions q0 around 50 and 56 whereas a lower attenuation q0 around 69 and 67 is assigned to the northern and eastern regions results show that the q 1 values are frequency dependent in the considered frequency range and are approximated by a least square fit to the power law q 1 f q 1 f f 0 the exponents of the frequency dependence law ranged from 0 65 to 1 01 for q 1 0 62 to 1 78 for q 1 0 28 to 1 49 for q 1 and 0 53 to 1 67 for q 1 on the other hand intrinsic absorption is found to dominate over scattering in the attenuation process for most of the stations and frequency bands analysed some discrepancies have been observed between the theoretical model and the observations for some frequency bands which indicate that it would be necessary to consider models for depth dependent velocity structure and or non isotropic scattering patterns

modeled methanesulfonic acid msa deposition in antarctica and its relationship to sea ice 1 methanesulfonic acid msa has previously been measured in ice cores in antarctica as a proxy for sea ice extent and southern hemisphere circulation in a series of chemical transport model geos chem sensitivity experiments we identify mechanisms that control the msa concentrations recorded in ice cores sea ice is linked to msa via dimethylsulfide dms which is produced biologically in the surface ocean and known to be particularly concentrated in the sea ice zone given existing ocean surface dms concentration data sets the model does not demonstrate a strong relationship between sea ice and msa deposition in antarctica the variability of dms emissions associated with sea ice extent is small 11 30 due to the small interannual variability of sea ice extent wind plays a role in the variability in dms emissions but its contribution relative to that of sea ice is strongly dependent on the assumed dms concentrations in the sea ice zone atmospheric sulfur emitted as dms from the sea ice undergoes net transport northward our model runs suggest that dms emissions from the sea ice zone may account for 26 62 of msa deposition at the antarctic coast and 36 95 in inland antarctica though our results are sensitive to model assumptions it is clear that an improved understanding of both dms concentrations and emissions from the sea ice zone are required to better assess the impact of sea ice variability on msa deposition to antarctica

landslides along the jordanian dead sea coast triggered by the lake level lowering the level of the dead sea lowers 1 m year and this rate is in acceleration the decline is causing one of the major environmental disasters of the twenty first century the freshwater resources management policy of israel jordan and palestine controls the phenomenon since the 1960s the level of this terminal lake dropped by 28 m and its surface shrunk by one third in the 1990s international builders created major tourist resorts and industrial plants along the jordanian shore while during the same period geological hazards triggered by the level lowering spread out from the very beginning of the year 2000 sinkholes subsidence landslides and river erosion damaged infrastructures more and more frequently dikes bridges roads houses factories pipes crops etc until present scientific articles about this ongoing disaster concerned only sinkholes and subsidence phenomena this paper focuses on the landslides issue along the jordanian coast based on a set of ground observations collected since 1999 the dynamics of the triggering factors in relation to the evolution of the hydro geological setting is discussed it is inferred that the recent industrial and tourist infrastructures never took into consideration the very important geotechnical constraints resulting from the dead sea lowering

sinkhole hazards along the eastern dead sea shoreline area jordan a geological and geotechnical consideration for the last four decades the level of the dead sea has been subjected to continual variation which among other important factors has led to the occurrence of much subsidence and many sinkholes in the southern dead sea area sinkhole activities occurred repetitively and were observed in open farms across roads near dwellings and near an existing factory thus causing a serious threat to the locals and farmers of the area and their properties this paper presents the main results from detailed geological and geotechnical studies of this area aerial photo interpretation and borehole drilling aided these studies parallel geophysical investigations vertical electrical sounding and seismic refraction and hydrological and hydrogeological studies were made by others in the same area to also investigate this phenomenon it was found that sinkholes are aligned to and follow old water channels and are concentrated parallel to the recent shoreline of the dead sea the development of subsurface cavities is associated mainly with the variation in the level of the dead sea over the four past decades the presence of regional salt intrusion under the surface of salt beds the fluctuation of the water table and continuous dissolution and the active tectonism of the area moreover this work showed that the area is still under active sinkhole hazards and other parts of the area will be inevitably affected by sinkholes in the future no practical engineering solution to this problem is feasible

sources of groundwater salinity along the flow path disi dead sea jordan the groundwater along the eastern escarpment of the dead sea shows a variety of chemical compositions with ec values ranging between 500 and a few thousand s cm in this article the different groundwaters were correlated to the aquifers from where they originate and the water rock interactions were elaborated at it was found that the start of intercalations of permo triassic and jurassic rocks in the area and the basaltic dykes and sills are the sources which cause a drastic increase in the salinity of the water these rocks contents of residual evaporites contact metamorphism products sills dykes and secondary altered mineral assemblage of plagioclase pyroxenes and fe mn minerals cause also drastic changes in ionic ratios saturation indices and groundwater types fresh groundwater flows entering the area become gradually after a few kilometres highly salinized and of earthalkali type with prevailing chloride and sulfate instead of being bicarbonate waters

sinkholes subsidence and subrosion on the eastern shore of the dead sea as revealed by a close range photogrammetric survey abstract ground subsidence and sinkhole collapse are phenomena affecting regions of karst geology worldwide the rapid development of such phenomena around the dead sea in the last four decades poses a major geological hazard to the local population agriculture and industry nonetheless many aspects of this hazard are still incompletely described and understood especially on the eastern dead sea shore in this work we present a first low altitude our analysis reveals a kilometer scale sinuous depression bound partly by flexure and partly by non tectonic faults the estimated minimum volume loss of this subsided zone is 1 83 106 m3 with an average subsidence rate of 0 21 m yr 1 over the last 25 years sinkholes in the surveyed area are localized mainly within this depression the sinkholes are commonly elliptically shaped mean eccentricity 1 31 and clustered nearest neighbor ratio 0 69 their morphologies and orientations depend on the type of sediment they form in in mud sinkholes have a low depth to diameter ratio 0 14 and a long axis azimuth of nne ne in alluvium sinkholes have a higher ratio 0 4 and are orientated nnw n from field work we identify actively evolving artesian springs and channelized sediment laden groundwater flows that appear locally in the main depression consequently subrosion i e subsurface mechanical erosion is identified as a key physical process in addition to dissolution behind the subsidence and sinkhole hazard furthermore satellite image analysis links the development of the sinuous depression and sinkhole formation at ghor al haditha to preferential groundwater flow paths along ancient and current wadi riverbeds