varves of the dead sea sedimentary record abstract the sedimentary record of the dead sea provides an exceptional high resolution archive of past climate changes in the drought sensitive eastern mediterranean levant a key region for the development of humankind at the boundary of global climate belts moreover it is the only deep hypersaline lake known to have deposited long sequences of finely laminated annually deposited sediments i e varves of varied compositions including aragonite gypsum halite and clastic sediments vast efforts have been made over the years to decipher the environmental information stored in these evaporitic clastic sequences spanning from the pleistocene lake amora to the holocene dead sea a general characterisation of sediment facies has been derived from exposed sediment sections as well as from shallow and deep water sediment cores during high lake stands and episodes of positive water budget mostly during glacial times alternating aragonite and detritus laminae aad facies were accumulated whereas during low lake stands and droughts prevailing during interglacials laminated detritus ld facies and laminated halite lh facies dominate the sequence in this paper we i review the three types of laminated sediments of the dead sea sedimentary record aad ld and lh facies ii discuss their modes of formation deposition and accumulation and their interpretation as varves and iii illustrate how dead sea varves are utilized for palaeoclimate reconstructions and for establishing floating chronologies

redistribution of dynamic stress during coseismic ruptures evidence for fault interaction and earthquake triggering we investigate the spatiotemporal evolution of dynamic stress outside a rupturing extended fault the dynamic stress variations caused by a coseismic rupture in a half space are computed by using the discrete wavenumber and reflectivity methods after a transient phase the stress time history evolves to the final static stress value we compare the static stress changes resulting from this model with those computed from a static dislocation model we have applied this method to study the interactions between the first two normal faults which ruptured during the 1980 ms 6 9 irpinia earthquake these two subevents are separated in time by nearly 20 s while the third and last subevent occurred 40 s after the rupture onset we compute the dynamic stress changes caused by the rupture of the first subevent our modeling results show that the dynamic stress peak on the second subevent fault plane is reached between 7 s and 8 s after the rupture initiation on the main fault on the average the static stress level on the second subevent 20 s fault plane is reached nearly after 14 s the dynamic rupture did not jump from a rupturing segment to the adjacent one immediately but the triggering of the 20 s subevent is delayed by roughly 10 s with respect to the instant of occurrence of the dynamic stress peak induced by the 0 s event the dynamic stress pulse propagates along the strike direction of the second subevent fault plane at an average velocity of nearly 3 4 km s the delayed triggering of the second subevent can be interpreted in terms of the frictional properties of the faults in particular rate and state dependent frictional law can explain a delayed instability after a sudden change in stress using the estimated values of the subevent triggering delay and the shear stress change we attempt to constrain the parameter a on the 20 s fault the values here inferred agree well with those resulting from previous studies

automated feature extraction and spatial organization of seafloor pockmarks belfast bay maine usa article i nfo seafloor pockmarks occur worldwide and may represent millions of m 3 of continental shelf erosion but few numerical analyses of their morphology and spatial distribution of pockmarks exist we introduce a quantitative definition of pockmark morphology and based on this definition propose a three step geomorphometric method to identify and extract pockmarks from high resolution swath bathymetry we apply this gis implemented approach to 25 km 2 of bathymetry collected in the belfast bay maine usa pockmark field our model extracted 1767 pockmarks and found a linear pockmark depth to diameter ratio for pockmarks field wide mean pockmark depth is 7 6 m and mean diameter is 84 8 m pockmark distribution is non random and nearly half of the field s pockmarks occur in chains the most prominent chains are oriented semi normal to the steepest gradient in holocene sediment thickness a descriptive model yields field wide spatial statistics indicating that pockmarks are distributed in non random clusters results enable quantitative comparison of pockmarks in fields worldwide as well as similar concave features such as impact craters dolines or salt pools published by elsevier b v

geomorphometry and landform mapping what is a landform abstract starting from a concept of the land surface its definition and subdivision from digital elevation models dems is considered high resolution dems from active remote sensing form a new basis for geomorphological work which is moving on from consideration of whether data are accurate enough to how the surface of interest can be defined from an overabundance of data discussion of the operational definition and delimitation of specific landforms of varying degrees of difficulty from craters to mountains is followed by the applicability of fuzzy boundaries scaling usually allometric is shown to be compatible with the scale specificity of many landforms this is exemplified by glacial cirques and drumlins classification of a whole land surface is more difficult than extraction of specific landforms from it well dissected fluvial landscapes pose great challenges for areal analyses these are tackled by the delimitation of homogeneous elementary forms and or land elements in which slope position is considered the boundaries are mainly breaks in gradient or aspect but may also be in some type of curvature breaks in altitude are rare elementary forms or land elements are grouped together into functional regions landforms such as hill sheds it may often be useful to recognise fuzziness of membership or core and periphery of a surface object plains and etched or scoured surfaces defy most of these approaches and general geomorphometry remains the most widely applicable technique it has been applied mainly within arbitrary areas and to some extent to drainage basins but more experimentation with mountain ranges and other landforms or landform regions is needed geomorphological mapping is becoming more specialised and its legends are being simplified its incorporation into geographical information systems gis has required greater precision with definitions and the separation of thematic layers so that it is converging with specific geomorphometry and becoming more flexible and more applicable with a broader range of visualisation techniques

reevaluation of the oxygen isotopic composition of planktonic foraminifera experimental results and revised paleotemperature equations cultured planktonic foraminifera orbulina universa symbiotic and globigerina bulloides nonsymbiotic are used to reexamine temperature 18o relationships at 15 25 c relationships for both species can be described by linear equations equations for o universa grown under low light ll and high light hl share a slope of 4 80 0 21 c 1 with a hl ll offset of 0 33 due to symbiont photosynthetic activity the effect of co32 on o universa is 0 002 mol 1 kg 1 and is insensitive to temperature for g bulloides ontogenetic effects produce size related trends in temperature 18o whereby larger shells are enriched in 18o relative to smaller specimens the o universa temperature 18o relationships are more accurate than previously published equations for describing plankton tow data our equations do not explain planktonic core top data with the same precision but provide a good fit to benthic cibicidoides data below 10 c temperature 18o relationships for g bulloides provide good agreement with field data for this species from the northeast pacific

oxygen and hydrogen isotopes in the hydrologic cycle changes of the isotopic composition of water within the water cycle provide a recognizable signature relating such water to the different phases of the cycle the isotope fractionations that accompany the evaporation from the ocean and other surface waters and the reverse process of rain formation account for the most notable changes as a result meteoric waters are depleted in the heavy isotopic species of h and o relative to ocean waters whereas waters in evaporative systems such as lakes plants and soilwaters are relatively enriched during the passage through the aquifers the isotope composition of water is essentially a conservative property at ambient temperatures but at elevated temperatures interaction with the rock matrix may perturb the isotope composition these changes of the isotope composition in atmospheric waters surface water soil and groundwaters as well as in the biosphere are applied in the characterization of hydrological system as well as indicators of paleo climatological conditions in proxy materials in climatic archives such as ice lake sediments or organic materials

re visiting the tectonics of the oceanic intraplate earthquake of march 25 1998 m 8 1 in the balleny sea offshore antarctica abstract the antarctic plate earthquake of march 25 1998 m 8 1 and its aftershocks are re visited to evaluate the role of the associated tectonics in stress concentration due to ambient horizontal crustal motion caused by deglaciation in antarctica using a numerical technique called the distinct element method a two dimensional structural model of the epicentral region is developed and tectonically loaded for a year along the inferred direction of the motion a spatial correlation is observed between the resulting locations of relatively high shear stresses and those of the main shock and associated aftershocks in particular seismicity is concentrated at and near the intersections of the main fault carey and gambier fracture zones where the shear stresses are significantly elevated and whose sign duplicate the inferred sense of movement along them the modeling results suggest that stress concentrations near pre existing intersecting fault and fracture zones due to a possible deglaciation induced horizontal crustal force may have been a cause of this enigmatic earthquake

carbon and oxygen isotope study of the active water carbonate system in a karstic mediterranean cave implications for paleoclimate research in semiarid regions abstract in a semiarid climatic zone such as the eastern mediterranean region annual rainfall variations and fractionation processes in the epikarst zone exert a profound influence on the isotopic compositions of waters seeping into a cave consequently the isotopic compositions of speleothems depositing from cave waters may show complex variations that need to be understood if they are to be exploited for paleoclimate studies this is confirmed by a four year study of the active carbonate water system in the soreq cave israel the 18o smow values of cave waters range from 6 3 to 3 5 the highest 18o values occur at the end of the dry season in waters dripping from stalactites and reflect evaporation processes in the epikarst zone whereas the lowest values occur in rapidly dripping fast drip waters at the peak of the rainy seasons however even fast drip waters are about 1 5 heavier than the rainfall above the cave which is taken to reflect the mixing of fresh with residual evaporated water in the epikarst zone 13c pdb values of dissolved inorganic carbon dic vary from 15 6 to 5 4 with fast drip waters having lower 13c values mostly 15 6 to 12 and higher dic concentrations relative to pool and stalactite drip water the low 13c values of fast drip waters and their supersaturation with respect to calcium carbonate indicates that the seepage waters have dissolved both soil co2 derived from overlying c3 type vegetation and marine dolomite host rock the 18o pdb values of various types of present day low magnesium calcite lmc speleothems range from 6 5 to 4 3 and 13c values from 13 to 5 5 and are not correlated with speleothem type an analysis of 18o values of present day calcite rafts and pool waters shows that they form in oxygen isotope equilibrium similarly the measured ranges of 13c and 18o values for all types of present day speleothems are consistent with equilibrium deposition at cave temperatures the 13c 18o range of contemporary lmc thus reflects the variations in temperatures and isotopic compositions of the presentday cave waters the 10 variation in the 13c values in waters can be modeled by a simple rayleigh calculation of the carbon isotope fractionation accompanying co2 degassing and carbonate precipitation these variations may obscure the differences in the carbon isotopic composition of speleothems that could arise when vegetation cover changes from c3 to c4 type plants this consideration emphasizes that it is necessary to characterize the full range of 13c values associated with contemporaneous speleothems in order to clarify the effects of degassing from those due to differing vegetation types isotopic studies of a number of different types of fossil lmc speleothems show many of them to exhibit isotopic trends that are similar to those of present day lmc but others show both higher and lower 18o ranges in particular the higher 18o range has been shown by independent age measurements to be associated with a period of drier conditions the results of the study thus indicate that it is necessary to work on a well calibrated cave system in semiarid climates and that the fossil speleothem record should be obtained from different types of contemporaneous deposit in order to fully characterize the 18o 13c range representative of any given climatic period

sea rain lake relation in the last glacial east mediterranean revealed by δ18o δ13c in lake lisan aragonites we investigated the sea rain lake relation during the last glacial holocene in the east med iterranean region by comparing the 18 o and 13 c records of authigenic aragonite deposited in lake lisan the dead sea mediterranean foraminifera and speleothems the lisan formation data display long and short term variations of 18 o representing steady state conditions of the lake e g 5 6 0 5 and 4 5 1 in the upper and lower members of the lisan formation respectively and short term excursions reflecting large floods and droughts the long term steady state 18 o values of the lisan aragonites show similarity to the corresponding time equivalent records of the eastern mediterranean foraminifera and judea mountain speleothems the last glacial deposits are in all of them 2 3 heavier than the holocene ones we interpret this similarity as reflecting the significance of the source effect on the long term behavior of isotopic reservoirs speleothem 18 o is strongly influenced by the marine reservoir that contributes its vapor to rain formation the lake 18 o is dominated by the composition of the inflowing water short term variations in the isotopic composition of rainfall are dominated by the amount effect and the temperature and those of the lake s upper water mass by the lake s water balance 13 c values are more variable than 18 o in the same lisan sequences e g 13 c in the lower member is 1 0 1 7 whereas 18 o is 4 6 0 7 and are 1 to 1 5 higher in the upper member than in the lower and middle members of the lisan formation these variations reflect significant increase in primary productivity of the lake and algal bloom activity it appears that the hypersaline saline lakes were not as dead as the dead sea is and that algal activity had an important impact upon the geochemistry of lake lisan the 18 o data combined with independent geochemical and limnologic information e g level fluctuations indicate that lisan time was characterized by high precipitation high lake stands high atmospheric humidity whereas the holocene dead sea shows the opposite behavior this paleoclimatic reconstruction is consistent with independent evidence for significantly wetter conditions in the east mediterranean region during the last glacial period copyright 2005 elsevier ltd

hydro climate research of the late quaternary of the eastern mediterranean levant region based on speleothems research a review abstract the eastern mediterranean em levant region is the eastern borderland of the eastern mediterranean sea ems the ems brings mediterranean climate zones to the immediate coastal region and hinterland but away from the influence of the ems the region rapidly becomes a desert paleoclimate evidence derived from a large number of studies on speleothems from caves located along sharp climatic gradients enables deep insight into the climate in the em levant region growth periods and isotopic composition of speleothems from the various climate regimes capture the regional signals of temperature rainfall amount and vegetation speleothems from northern and central israel grew continuously in areas where present day annual rainfall is 400 500 mm and show that water was always available during glacials and interglacials these speleothems display a well defined 18o orbital modulation of glacial and interglacial marine isotope stages mis and show good correlations with the ems marine records pointing to strong direct sea land links the climatic record indicates relatively drier and cooler glacials but extreme wet peaks during interglacials mainly mis 5e between 128 120 ka bp pluvial conditions penetrated to the northern central and southern negev desert the present day climatic gradient between the different climatic regions existed through interglacials however growth periods of speleothems from the northern negev desert from the rain shadow desert and the dead sea basin suggest that during last glacial the desert boundary moved from its interglacial and present day position 30 km farther south and 60 km farther east due to positive water balance

automated object based classification of topography from srtm data we introduce an object based method to automatically classify topography from srtm data the new method relies on the concept of decomposing land surface complexity into more homogeneous domains an elevation layer is automatically segmented and classified at three scale levels that represent domains of complexity by using self adaptive data driven techniques for each domain scales in the data are detected with the help of local variance and segmentation is performed at these appropriate scales objects resulting from segmentation are partitioned into sub domains based on thresholds given by the mean values of elevation and standard deviation of elevation respectively results resemble reasonably patterns of existing global and regional classifications displaying a level of detail close to manually drawn maps statistical evaluation indicates that most of classes satisfy the regionalization requirements of maximizing internal homogeneity while minimizing external homogeneity most objects have boundaries matching natural discontinuities at regional level the method is simple and fully automated the input data consist of only one layer which does not need any pre processing both segmentation and classification rely on only two parameters elevation and standard deviation of elevation the methodology is implemented as a customized process for the ecognition software available as online download the results are embedded in a web application with functionalities of visualization and download

late quaternary paleoclimate in the eastern mediterranean region from stable isotope analysis of speleothems at soreq cave israel abstract the eastern mediterranean continental paleoclimate during the past 25 000 years was determined by a high resolution petrographic stable isotopic and age study of speleothems from soreq cave israel 18o 13c trends indicate that all speleothems older than 7000 yr formed under conditions that differ from those of today the period from 25 000 to 17 000 yr b p was characterized by the highest 18o and 13c values which indicate deposition at temperatures of 12 16 c annual rainfall of 300 450 mm and vegetation typical of a mixed c3 c4type from 17 000 to 10 000 yr b p deglaciation in northern europe 18o values dropped progressively correlative with warming 2 3 c and a gradual increase in precipitation a simultaneous decrease in 13c gives a range expected for c3 type vegetation this period also shows significant 18o and 13c spikes which are correlatable with global events e g heinrich events and the younger dryas stade the speleothems that grew between 10 000 and 7000 yr b p have a unique petrography showing irregular thin laminae of various colors and much detritus they have the lowest 18o corresponding to 1000 mm rain coupled with the highest 13c caused by flooding events which stripped the soil cover from 7000 to 1000 yr b p conditions became closer to those of today this study demonstrates that global events which were recognized in northern europe and north africa are also evident in the eastern mediterranean and are reflected principally by large changes in the rainfall rate

paleoclimatology of the levant from zalmon cave speleothems the northern jordan valley israel abstract the levant region of israel located along the eastern mediterranean sea is characterized by mediterranean climate but sixty km eastwards towards the dead sea rift valley dsrv the region rapidly becomes a rain shadow desert speleothems from the mediterranean climate zone continuously grew throughout several glacial interglacial cycles indicating that water was always available in the unsaturated zone their 18o variations match global and regional climate changes with the eastern mediterranean sea being the major control on their 18o values as evident from the similarity between the speleothems and the planktonic foraminifer g ruber records in contrast speleothems along the central and southern segments of the dsrv grew mainly during last glacial periods coinciding with the higher stands of lake lisan the precursor of the present day dead sea this paper discusses the newly discovered zalmon cave speleothems located in the northern segment of the dsrv shedding light on the hydrological conditions along the rift during last glacial unlike speleothems located further south along the dsrv zalmon cave speleothems grew both during glacial and interglacial periods however during last glacial their 18o values shifted to lower values by 1 2 relative to speleothems from central israel coinciding also with the largest difference in 18o values between zalmon cave speleothems and the marine record the data suggest that a change of the westerlies storm tracks occurred during most of the last glacial period which resulted in increased rainfall in the northern dsrv providing freshwater input during the otherwise relatively drier glacial

changes in static stress on southern california faults after the 1992 landers earthquake the magnitude 7 5 landers earthquake of 28 june 1992 was the largest earthquake to strike california in 40 years the slip that occurs in such an earthquake would be expected to induce large changes in the static stress on neighbouring faults these changes in stress should in turn affect the likelihood of future earthquakes stress changes that load faults towards failure have been cited as the cause of small1 5 moderate6 and large7 earthquakes conversely those that relax neighbouring faults have been related to a decrease in seismicity5 here we use an elastic half space model8 to estimate the stress changes produced by the landers earthquake on selected southern california faults including the san andreas we find that the estimated stress changes are consistent with the triggering of four out of the five aftershocks with magnitude greater than 4 5 and that the largest changes 1 10 bar occurring on part of the san bernardino segment of the san andreas fault may have decreased the time to the next magnitude 8 earthquake by about 14 years

spectral signatures of characteristic spatial scales and nonfractal structure in landscapes 1 landscapes are sometimes argued to be scale invariant or random surfaces yet qualitative observations suggest that they contain characteristic spatial scales we quantitatively investigate the existence of characteristic landscape scales by analyzing two dimensional fourier power spectra derived from high resolution topographic maps of two landscapes in california in both cases we find that spectral power declines sharply above a frequency that corresponds roughly to hillslope length implying that the landscape is relatively smooth at finer scales the spectra also show that both landscapes contain quasiperiodic ridge and valley structures and we derive a robust measure of the ridge valley wavelength by comparing the spectra with the statistical properties of spectra derived from randomly generated topography we show that such uniform valley spacing is unlikely to occur in a random surface we describe several potential applications of spectral analysis in geomorphology beyond the identification of characteristic spatial scales including a filtering technique that can be used to measure topographic attributes such as local relief at specific scales or in specific orientations

did stress triggering cause the large off fault aftershocks of the 25 march 1998 mw 8 1 antarctic plate earthquake the 1998 antarctic plate earthquake produced clusters of aftershocks mw 6 4 up to 80 km from the fault rupture and up to 100 km beyond the end of the rupture because the mainshock occurred far from the nearest plate boundary and the nearest recorded earthquake it is unusually isolated from the stress perturbations caused by other earthquakes making it a good candidate for stress transfer analysis despite the absence of near field observations we tested whether the off fault aftershocks lie in regions brought closer to coulomb failure by the main rupture we evaluated four published source models for the main rupture in fourteen tests using different aftershocks sets and allowing the rupture sources to be shifted within their uncertainties 6 were significant at 99 confidence 3 at 95 confidence and 5 were not significant 95 level for the 9 successful tests the stress at the site of the aftershocks was typically increased by 1 2 bars 0 1 0 2 mpa thus the antarctic plate event together with the 1992 mw 7 3 landers and its mw 6 5 big bear aftershock 40 km from the main fault supply evidence that small stress changes might indeed trigger large earthquakes far from the main fault rupture

automated landslide mapping using spectral analysis and high resolution topographic data puget sound lowlands washington and portland hills oregon abstract landslide inventory maps are necessary for assessing landslide hazards and addressing the role slope stability plays in landscape evolution over geologic timescales however landslide inventory maps produced with traditional methods aerial photograph interpretation topographic map analysis and field inspection are often subjective and incomplete the increasing availability of high resolution topographic data acquired via airborne light detection and ranging lidar over broad swaths of terrain invites new automated landslide mapping procedures we present two methods of spectral analysis that utilize lidar derived digital elevation models of the puget sound lowlands washington and the tualatin mountains oregon to quantify and automatically map the topographic signatures of deep seated landslides power spectra produced using the two dimensional discrete fourier transform and the two dimensional continuous wavelet transform identify the characteristic spatial frequencies of deep seated landslide morphologic features such as hummocky topography scarps and displaced blocks of material spatial patterns in the amount of spectral power concentrated in these characteristic frequency bands highlight past slope instabilities and allow the delineation of landslide terrain when calibrated by comparison with detailed independently compiled landslide inventory maps our algorithms correctly classify an average of 82 of the terrain in our five study areas spectral analysis also allows the creation of dominant wavelength maps which prove useful in analyzing meter scale topographic expressions of landslide mechanics past landslide activity and landslide modifying geomorphic processes these results suggest that our automated landslide mapping methods can create accurate landslide maps and serve as effective objective and efficient tools for digital terrain analysis

surficial patterns of debris flow deposition on alluvial fans in death valley ca using airborne laser swath mapping data debris flows are a common event in mountainous environments they often possess the greatest potential for destruction of property and loss of lives in these regions delimiting the spatial extent of potential damage from debris flows relies on detailed studies of the location of depositional zones current research indicates debris flow fans have two distinct depositional zones however the two zones were derived from studies containing detailed analyses of only a few fans high resolution airborne laser swath mapping alsm data is used to calculate profile curvature and surface gradient on 19 debris flow fans on the eastern side of death valley the relationship between these parameters is assessed to 1 identify if debris flow fans are accurately represented by two depositional zones and 2 to assess how these terrain parameters relate to one another at the individual fan scale the results show at least three zones of deposition exist within the sampled fans these zones do not hold consistent when individual fan morphometry is analyzed in conjunction with localized fan surface gradients fans with consistently shallower gradients exhibit numerous depositional zones with more subtle changes in profile curvature steeper gradient fans exhibit significantly fewer zones with more pronounced local changes in profile curvature the surface complexity of debris flow fans is evident from these analyses and must be accounted for in any type of hazard studies related to these features

stress interactions of three moderate size earthquakes in afyon southwestern turkey abstract we analyze three moderate size earthquakes occurred in the afyon region of southwestern turkey on december 15 2000 m w 6 0 and february 3 2002 m w 6 5 and m w 5 8 this earthquake sequence took place on the sultandag fault having dominantly normal faulting mechanisms with different orientations in an extensional tectonic regime we relocate these mainshocks and their large aftershocks and use the waveform data to determine the rupture dimensions and directivities we carry out both static and dynamic stress analysis to investigate stress interactions and possible earthquake triggering mechanisms in this sequence we show that the 2002 m w 6 5 rupture started at the termination of the 2000 m w 6 0 earthquake where the calculated coulomb stress changes increased more than 0 5 bar thus we conclude that the coseismic stress increase by the 2000 event favored the nucleation and promoted the timing of the 2002 event an intense seismic activity identified as the kizildag aftershock zone developed following both of the large mainshocks where the third largest earthquake m w 5 8 of the sequence occurred 2 h after the 2002 m w 6 5 mainshock the coulomb stress calculations of the 2000 earthquake shows no influence in this zone while the static coulomb stress changes due to the 2002 m w 6 5 mainshock raised the coulomb stresses an additional 0 3 0 7 bar in the kizildag aftershock zone thus we infer that such changes in the coulomb stresses positively influence the occurrence of the aftershocks in this zone since the kizildag aftershock zone takes place in a geothermal area we compute dynamic stress changes imposed by the 2000 and 2002 mainshocks the computed peak dynamic stress levels for both mainshocks are found much higher than the static stress changes calculated within the kizildag aftershock zone thus we propose that transient stress triggering most likely involving elevated fluid pressures in the hydrothermal systems present in this region may have played a major role in the initiation of increased seismicity followed by local multiple elastic stress triggering leading to the further development of aftershocks and the occurrence of the m w 5 8 mainshock

sea land oxygen isotopic relationships from planktonic foraminifera and speleothems in the eastern mediterranean region and their implication for paleorainfall during interglacial intervals the oxygen and carbon stable isotope compositions of cave speleothems provide a powerful method for understanding continental climate change here we examine the question of the regionality of this isotopic record and its linkage with the marine isotopic record in the eastern mediterranean em region the study presents a new accurately dated 250 kyr 18o and 13c record determined from speleothems of the peqiin cave northern israel its comparison with the continuous 185 kyr isotopic record of the soreq cave speleothems from central israel reveals striking similarities thus a strong regional climatic signal brought about by variations in temperature and rainfall amount is reflected in both cave records low 18o minima in the peqiin profile for the last 250 to 185 kyr period interglacial marine isotopic stage 7 match the timing of sapropels 9 to 7 and are indicative of high rainfall in the em region at these times the combined soreq and peqiin 18o record for the last 250 kyr excellently matches the published globigerinoides ruber g ruber marine 18o record for the em sea with the isotopic compositional difference g ruber speleothems remaining relatively constant at 5 6 0 7 thus establishing for the first time a robust exploitable link between the land and the marine isotopic records the correspondence of low 18o speleothem values and high cave water stands with low g ruber 18o values during interglacial sapropel events indicates that these periods were characterized by enhanced rainfall in the em land and sea regions by use of sea surface temperatures derived from alkenone data as a proxy for land temperatures at the soreq cave we calculate the paleorainfall 18o values and its amounts maximum rainfall and lowest temperature conditions occurred at the beginning of the sapropel events and were followed by decrease in rainfall and increase in temperatures leading to arid conditions the record for the last 7000 yr shows a trend toward increasing aridity and agrees well with climatic and archeological data from north africa and the middle east

relation between mainshock rupture process and omori s law for aftershock moment release rate summary we compare the source time functions i e moment release rates of three large california mainshocks with the seismic moment release rates during their aftershock sequences aftershock moment release rates computed by summing aftershock moments in time intervals follow a power law time dependence similar to omori s law from minutes to months after the mainshock furthermore in contrast to the previously observed saturation in numbers of aftershocks shortly after the mainshock rupture no such saturation is seen in the aftershock moment release rates which are dominated by the largest aftershocks we argue that the observed saturation in aftershock numbers described by the time offset parameter c in omori s law is likely an artefact due to the underreporting of small aftershocks which is related to the difficulty of detecting large numbers of small aftershocks in the mainshock coda we further propose that it is more natural for c to be negative i e singularity follows the onset of mainshock rupture than positive singularity precedes onset of rupture to make a more general comparison of mainshock rupture process and aftershock moment rates we then scale mainshock time functions to equalize the effects of the varied seismic moments for the three california mainshocks we compare the scaled time functions with similarly scaled aftershock moment rates finally we compare global averages of scaled time functions of many shallow events to the average scaled aftershock moment release rate for six california mainshocks in each of these comparisons the extrapolation using omori s law of the aftershock moment rates back in time to the onset of the mainshock rupture indicates that the temporal intensity of the aftershock moment release is about 1 5 orders of magnitude less than the maximum reached by the mainshock rupture this may be due to the differing amplitudes and relative importance of static and dynamic stresses in aftershock initiation compared to mainshock rupture propagation

reply to comment on ben dor y et al varves of the dead sea sedimentary record quaternary science reviews 215 2019 173 184 abstract in the comment on varves of the dead sea sedimentary record quaternary science reviews 215 ben dor et al 2019 173 184 by r bookman two recently published papers are suggested to prove that the interpretation of the laminated sedimentary sequence of the dead sea deposited mostly during mis2 and holocene pluvials as annual deposits i e varves is wrong in the following response we delineate several lines of evidence which coalesce to demonstrate that based on the vast majority of evidence including some of the evidence provided in the comment itself the interpretation of these sediments as varves is the more likely scientific conclusion we further discuss the evidence brought up in the comment and its irrelevance and lack of robustness for addressing the question under discussion

a new understanding of the provinces of the amazon craton based on integration of field mapping and u pb and sm nd geochronology abstract new conventional and sensitive high resolution ion microprobe zircon u pb dating has led to a new understanding of the subdivision and evolution of the amazon craton during precambrian time with major improvements and changes made to the previous rb sr based model the interpretation of u pb and sm nd isotopic data identifies eight main precambrian tectonic provinces in the craton with ages ranging from 3 1 to 0 99 ga some of the provinces were generated by accretional arc related processes carajas transamazonic tapajos parima and rondonia juruena and others by recycling of continental crust central amazon rio negro and sunsas the exposed archean crust is restricted to the east carajas and south amapa in brazil and north imataca in venezuela of the craton indicating that the amazon craton is largely a proterozoic crust the carajas imataca 3 10 2 53 ga and transamazonian 2 25 2 00 ga provinces are composed predominantly of granite greenstone terranes the tapajos parima 2 10 1 87 ga and rondonia juruena 1 75 1 47 ga provinces represent new crust added as orogenic belts while the rio negro 1 86 1 52 ga and sunsas 1 33 0 99 ga provinces originated mainly by magmatic tectonic recycling of the above two orogenic belts the only zone with a prominent northeast trend is the poorly known k mudku shear belt characterized by a 1 20 ga shear zone which deforms the rocks of at least three different provinces rio negro tapajos parima and transamazonic the central amazon province comprises mostly orosirian volcano plutonic rocks uatuma magmatism and is a terrane in which the exposed crustal structure and deformation are pluton related the sm nd tdm model ages and nd suggest that the central amazon province was generated by the partial melting of archean continental crust carajas province perhaps related to underplating that began at the end of the tapajos parima orogeny 1 88 1 86 ga

triggering of earthquake aftershocks by dynamic stresses it is thought that small static stress changes due to permanent fault displacement can alter the likelihood of or trigger earthquakes on nearby faults many studies of triggering in the near field particularly of aftershocks rely on these static changes as the triggering agent and consider them only in terms of equivalent changes in the applied load on the fault here we report a comparison of the aftershock pattern of the moment magnitude mw 7 3 landers earthquake not only with static stress changes but also with transient oscillatory stress changes transmitted as seismic waves that is dynamic stresses dynamic stresses do not permanently change the applied load and thus can trigger earthquakes only by altering the mechanical state or properties of the fault zone these dynamically weakened faults may fail after the seismic waves have passed by and might even cause earthquakes that would not otherwise have occurred we find similar asymmetries in the aftershock and dynamic stress patterns the latter being due to rupture propagation whereas the static stress changes lack this asymmetry previous studies have shown that dynamic stresses can promote failure at remote distances but here we show that they can also do so nearby

evidence of instantaneous dynamic triggering during the seismic sequence of year 2000 in south iceland 1 we analyze the coseismic stress perturbation during the 17 june 2000 south iceland seismic sequence the main shock ms 6 6 was followed by three large events within a few tens of seconds 8 26 and 30 s located within 80 km the aim of this paper is to investigate short term fault interaction and instantaneous triggering this happens when a fault perturbed by a stress change fails before the end of the transient stress perturbation we compute the shear normal and coulomb stress changes as functions of time in a stratified elastic half space by using discrete wave number and reflectivity methods we calculate dynamic stresses caused by the main shock at the hypocenters of these three subsequent events our numerical results show that the onset of the last two events is slightly delayed with respect to the arrival time of the second positive peak of coulomb stress variation while the first event occurred after the first positive stress peak we have also analyzed the response of a spring slider system representing a fault governed by a rate and state dependent friction law perturbed by shear and normal stress variations caused by the main shock the fault response to the computed stress perturbations is always clock advanced we have found suitable constitutive parameters of the modeled fault that allow the instantaneous dynamic triggering of these three earthquakes if the initial sliding velocity is comparable with the tectonic loading velocity we obtained failure times close to the observed origin times for low values of the initial effective normal stress

rupture propagation beyond fault discontinuities significance of fault strike and location summary earthquake rupture sometimes occurs on several faults and often decelerates or terminates at fault stepovers factors that control the rupture processes across stepovers are important for an understanding of earthquake growth and termination in this study we investigate such factors by calculating the spontaneous rupture processes of two non coplanar faults in a 3 d model dealing with two extreme models in which two strike slip faults are either parallel or perpendicular we show that the rupture processes beyond fault discontinuities are drastically different for the two models we find three factors influencing rupture processes beyond fault discontinuities depth of the upper edge of the two faults location of the edge of the first fault and geometry of the two faults these factors determine the time and location of rupture jumps to the second fault for rupture propagation to the second fault it is essential for rupture on the first fault to arrive at the edge of the fault in particular whether rupture on the first fault reaches the earth s surface or not controls the difficulty of rupture jumps and the locations where the rupture is triggered which is also related to the step direction of the two faults this is because the stress perturbation at the fault edge is affected by the earth s free surface

height above the nearest drainage a hydrologically relevant new terrain model summary this paper introduces a new terrain model named hand and reports on the calibration and validation of landscape classes representing soil environments in amazonia which were derived using it the hand model normalizes topography according to the local relative heights found along the drainage network and in this way presents the topology of the relative soil gravitational potentials or local draining potentials the hand model has been demonstrated to show a high correlation with the depth of the water table providing an accurate spatial representation of soil water environments normalized draining potentials can be classified according to the relative vertical flowpath distances to the nearest drainages defining classes of soil water environments these classes have been shown to be comparable and have verifiable and reproducible hydrological significance across the studied catchment and for surrounding ungauged catchments the robust validation of this model over an area of 18 000 km2 in the lower rio negro catchment has demonstrated its capacity to map expansive environments using only remotely acquired topography data as inputs the classified hand model has also preliminarily demonstrated robustness when applied to ungauged catchments elsewhere with contrasting geologies geomorphologies and soil types the hand model and the derived soil water maps can help to advance physically based hydrological models and be applied to a host of disciplines that focus on soil moisture and ground water dynamics as an original assessment of soil water in the landscape the hand model explores the synergy between digital topography data and terrain modeling presenting an opportunity for solving many difficult problems in hydrology

on the fidelity of shell derived δ18oseawater estimates article i nfo 18 oseawater a robustproxyforsurfacesalinity we assessthe fidelity of shell derived 18 oseawater estimates for the surface dwelling foraminifer globigerinoides ruber white using an atlantic meridional coretop transect spanning basin scale temperature and salinity gradients shell derived and observed 18 oseawater values are well correlated r 2 0 77 but a large systematic bias is observed shell mg ca ratios are significantly elevated above values expected from observed and isotopic calcification temperatures in the saline subtropical gyres of both hemispheres this temperature independent shell mg ca ratio variability termed excess mg ca i s highly correlated with surface salinity r 2 0 77 and the observed salinity dependence 27 4 is much higher than indicated by culture studies 6 2 our coretop data are used to develop new atlantic basin temperature and salinity calibration equations that are accurate 1 1 c and 0 20 respectively precise r 2 0 82 and 0 81 respectively and verifiable using previously published data these results are valid for the relatively high salinities of the subtropical atlantic 35 5 37 3 we discover that inclusion of other published data from lower salinity regions b35 indicates little or no excess mg ca taken together these results point to a strongly non linear positive salinity effect on shell mg ca ratios that significantly affects the accuracy of sst and 18

earthquake triggering by static and dynamic stress changes 1 in this study we aim to understand the effect of static and dynamic stress changes in promoting earthquake failures on secondary faults toward this goal we solve the equation of motion of a spring slider dynamic system including inertia and using rate and state dependent constitutive laws we separately investigate the dynamic response of this fault analog system to a sudden stress change represented either as a stress step or as a stress pulse which are used to model permanent static and transient dynamic stress perturbations the induced earthquake failure does not occur immediately at the application of the coseismic stress change but it is delayed in time we define this time interval as the triggering delay for a given stress perturbation we analyze the dependence of triggering delays on different system conditions and constitutive parameters our results clearly show that the effects of static and dynamic stress changes are quite different while a static stress change is able to advance as well as to delay an induced instability depending on its sign a dynamic stress pulse is only able to promote a nearly instantaneous failure provided its amplitude is positive and large enough with respect to the direct effect of friction in other words dynamic stress changes can only cause nearly instantaneous failures without any relevant triggering delay these results should be considered in interpreting the seismicity rate changes caused by large earthquakes at least as long as seismic events are interpreted as sliding instabilities obeying rate and state dependent friction laws

automated classifications of topography from dems by an unsupervised nested means algorithm and a three part geometric signature abstract an iterative procedure that implements the classification of continuous topography as a problem in digital image processing automatically divides an area into categories of surface form three taxonomic criteria slope gradient local convexity and surface texture are calculated from a square grid digital elevation model dem the sequence of programmed operations combines twofold partitioned maps of the three variables converted to greyscale images using the mean of each variable as the dividing threshold to subdivide increasingly subtle topography grid cells sloping at less than mean gradient of the input dem are classified by designating mean values of successively lower sloping subsets of the study area nested means as taxonomic thresholds thereby increasing the number of output categories from the minimum 8 to 12 or 16 program output is exemplified by 16 topographic types for the world at 1 km spatial resolution srtm30 data the japanese islands at 270 m and part of hokkaido at 55 m because the procedure is unsupervised and reflects frequency distributions of the input variables rather than pre set criteria the resulting classes are undefined and must be calibrated empirically by subsequent analysis maps of the example classifications reflect physiographic regions geological structure and landform as well as slope materials and processes fine textured terrain categories tend to correlate with erosional topography or older surfaces coarse textured classes with areas of little dissection in japan the resulting classes approximate landform types mapped from airphoto analysis while in the americas they create map patterns resembling hammond s terrain types or surface form classes srtm30 output for the united states compares favorably with fenneman s physical divisions experiments are suggested for further developing the method the arc info aml and the map of terrain classes for the world are available as online downloads

mobilization of fine detritus to the dead sea basin during the late glacial and early holocene abstract the mineralogical grain size and geochemical properties e g nd and sr isotopes mg al ratios of fine detritus that accumulated in the dead sea during the late glacial to early holocene time 22 7 ka are used to identify its sources and modes of transport and to reconstruct the hydroclimate conditions in the dead sea watershed samples were retrieved from the dsddp 5017 1a core that was drilled in the deep floor of the lake and from various exposures of surface cover in the lake s watershed the data show that during most of the late glacial detrital particles were either directly blown mostly from the north sahara desert or were washed from the surface cover loessial soils of the north negev desert and judea desert this picture changed during the end of the last glacial to the early holocene 14 7 ka when the fine detritus showed evidence for contribution from surface cover that contained basaltic soils the contribution of basaltic soils to the fine detritus inventory of the dead sea and to terraces in the jordan valley indicates a period of intense erosion in the northern highlands of the dead sea watershed at an interval that partly coincides with sapropel s1 in contrast during the last interglacial sapropel s5 fine detritus was mostly mobilized to the lake from southern and eastern region of the watershed the formation and accumulation of terraces from this basaltic derived material could be an important factor in the establishment of early agriculture settlements in the jordan valley

dynamic versus static stress triggering and friction parameters inferences from the november 23 1980 irpinia earthquake this paper concentrates on the problem of fault interaction and earthquake triggering through the 1980 irpinia italy sequence more specifically this paper deals with the problem of the triggering of the second subevent by the mainshock the interaction between the two segments is modeled through a dynamic coulomb failure function the aims of this paper are first to discriminate between the dynamic and the static stress effects on the triggering if these effects exist second to estimate the fault strength relative to the initial state of stress third to determine the parameters of a slip dependent friction law that lead to the observed delay of 20 s numerical simulations show that the critical slip dc may range from 0 03 m up to 1 7 m and that the initial slope of the friction law 0 must be lower than 0 04 m 1 we show that the relative magnitude of the fault strength and the initial state of stress govern the existence and value of a dc lower threshold under which the fault always ruptures before 13 s a close to failure fault is not consistent with a critical slip dc less than 0 8 m whereas small values of dc typically 0 03 m imply a far from failure fault general results concern the effect of a dynamic stress pulse we show that an event can be triggered by a transient stress pulse and that in this case the event can have an initiation duration much longer than the pulse duration we show that it is possible to explain both the triggering and the time delay only with the effect of the transient stress pulse this may explain aftershock triggering even in regions of negative coulomb failure function or long distance triggering of earthquakes by propagating waves

surface texture analysis of a high resolution dtm interpreting an alpine basin abstract this study focuses on a geomorphometric analysis of a small headwater basin of the dolomites eastern italian alps the analysis of the fine scale surface morphology was performed on a high resolution digital elevation model cell size 2 m derived from an airborne lidar survey the topography was synthesized by a set of spatial statistical indexes representing a signature of the local surface morphology and the relationships between the geomorphometric indexes and morphological features were evaluated the studied basin was then segmented by means of a fuzzy k means classification algorithm into different spatial subdomains characterized by specific local geomorphic signatures this method allows us to objectively choose the optimal combination of the number of classes and degree of fuzziness characterizing the studied basin accordingly the analysis can be adopted to the characteristics of the studied area improving the interpretation of surface morphology and offering a valuable tool for comparative analysis between different geomorphological contexts the results of the classification were compared with the actual surface morphology based on high resolution orthophotos aerial photos and field surveys

scaling relations of earthquake source parameter estimates with special focus on subduction environment abstract earthquake rupture length and width estimates are in demand in many seismological applications earthquake magnitude estimates are often available whereas the geometrical extensions of the rupture fault mostly are lacking therefore scaling relations are needed to derive length and width from magnitude most frequently used are the relationships of wells and coppersmith 1994 derived on the basis of a large dataset including all slip types with the exception of thrust faulting events in subduction environments however there are many applications dealing with earthquakes in subduction zones because of their high seismic and tsunamigenic potential there are no well established scaling relations for moment magnitude and length width for subduction events within this study we compiled a large database of source parameter estimates of 283 earthquakes all focal mechanisms are represented but special focus is set on large subduction zone events in particular scaling relations were fitted with linear least square as well as orthogonal regression and analyzed regarding the difference between continental and subduction zone oceanic relationships additionally the effect of technical progress in earthquake parameter estimation on scaling relations was tested as well as the influence of different fault mechanisms for a given moment magnitude we found shorter but wider rupture areas of thrust events compared to wells and coppersmith 1994 the thrust event relationships for pure continental and pure subduction zone rupture areas were found to be almost identical the scaling relations differ significantly for slip types the exclusion of events prior to 1964 when the worldwide standard seismic network was established resulted in a remarkable effect on strike slip scaling relations the data do not show any saturation of rupture width of strike slip earthquakes generally rupture area seems to scale with mean slip independent of magnitude the aspect ratio l w however depends on moment and differs for each slip type

continental oxygen isotopic record of the last 170 000 years in jerusalem abstract a long radiometrically dated oxygen isotopic record of continental climatic variations since the penultimate glaciation was obtained from a stalagmite deposited in a sealed cave in jerusalem this record shows that speleothems have the potential of assigning dates to long and short term climatic events with possible refining of milankovitch tuning of ice and marine records which themselves are not datable short term 1000 yr events are very significant in the region reaching 50 of glacial interglacial fluctuations the mediterranean sea was the most probable source of local precipitation throughout the last glacial cycle

modelling dynamic stress changes caused by an extended rupture in an elastic stratified half space summary we model the time histories of coseismic stress changes produced by an earthquake rupture on an extended fault in a layered elastic half space we compute the stress perturbations caused by earthquakes using the discrete wavenumber and the reflectivity methods we investigate the influence on the computed coulomb stress changes of the adopted crustal velocity model the rupture history and slip duration as well as the poro elastic model assumed to calculate the pore pressure changes the comparison between the spatio temporal evolution of the induced stress field calculated for different crustal models and rupture histories allows us to assess the depth and frequency dependence of the induced stress perturbation and the relative weight of dynamic and static stress changes our results show that the rise time and the rupture directivity are more important for characterizing the simulated stress time histories than the details of the rupture history the adopted poro elastic model affects the static stress changes more than the transient stress perturbations the results of this study should be taken into account to model fault interaction through elastic stress transfer

dynamics of fault interaction parallel strike slip faults we use a two dimensional finite difference computer program to study the effect of fault steps on dynamic ruptures our results indicate that a strike slip earthquake is unlikely to jump a fault step wider than 5 km in correlation with field observations of moderate to great sized earthquakes we also find that dynamically propagating ruptures can jump both compressional and dilational fault steps although wider dilational fault steps can be jumped dilational steps tend to delay the rupture for a longer time than compressional steps do this delay leads to a slower apparent rupture velocity in the vicinity of dilational steps these dry cases assumed hydrostatic or greater pore pressures but did not include the effects of changing pore pressures in an additional study we simulated the dynamic effects of a fault rupture on undrained pore fluids to test sibson s 1985 1986 suggestion that wet dilational steps are a barrier to rupture propagation our numerical results validate sibson s hypothesis by demonstrating that the effect of the rupture on the undrained pore fluids is to inhibit the rupture from jumping dilational stepovers the basis of our result differs from sibson s hypothesis in that our model is purely elastic and does not necessitate the opening of extension fractures between the fault segments

d h ratios of fluid inclusions of soreq cave israel speleothems as a guide to the eastern mediterranean meteoric line relationships in the last 120 ky abstract d h studies of fluid inclusions of speleothems of the soreq cave israel are made using the method of vacuum thermal extraction d h measurements of present day carbonate pool margins and waters show that the value of the vacuum thermal extraction fractionation ex d extracted water d cave water is 30 0 1 4 for the soreq cave deposits d h analyses of fluid inclusions of two fossil speleothems formed during periods equivalent to glacial times suggest that their isotopic compositions follow the global meteoric water line mwl d 18 o relationship compared to present day waters which follow the mediterranean meteoric water line mmwl trend two samples from interglacial periods show isotopic trends between these lines these differences are presumed to reflect cooler less evaporative conditions in the eastern mediterranean sea during glacial times

application of wavelet analysis to the study of spatial pattern of morphotectonic lineaments in digital terrain models a case study tectonic faults are often associated with characteristic geomorphological features such as linear valleys ridgelines and slope breaks that can be identified as lineaments in remotely sensed images or digital terrain models lineaments of tectonic origin are often characterised by periodicity and characteristic spatial pattern unlike traditional methods of autocorrelation variogram lineament density and fourier analysis wavelet analysis is capable of capturing and describing both periodicity and spatial pattern of lineaments in this paper a case study is shown for the application of wavelet analysis to morphotectonic lineament investigation results of wavelet analysis are compared to traditional methods although this study involves dem derived morphological lineaments the presented wavelet analysis can be also used for lineaments derived from remotely sensed images these results hold for this case study and provide a good assessment of the relative abilities of wavelet analysis but it remains to be seen how effective it is for other data sources areas and geological terrain

quantitative reconstruction of early holocene and last glacial climate on the balkan peninsula using coupled hydrological and isotope mass balance modelling abstract we investigate the modern hydrology of lake ohrid macedonia albania using a combined hydrological and isotope based modelling approach and present a new evaluation of contemporary water balance and palaeoclimate estimates the combined model is able to estimate hydrological components that cannot be directly measured and indicates that sublacustrine spring inflow is in the order of 50 higher than previous estimates and groundwater outflow comprises approximately a third of overall water outflow in combination with sediment core oxygen isotope data we used the combined model to quantitatively reconstruct past climate in particular precipitation during the early holocene and last glacial period calculated precipitation in the early holocene was higher than the value for present day and was approximately 44 lower than present during the last glacial assuming the majority of precipitation fell as snow the estimated amount of precipitation in the last glacial would have been high enough to provide refugial conditions at lake ohrid and to support the continuous existence of arboreal vegetation in the catchment the improved understanding of the modern isotope hydrology of lake ohrid is fundamental for explaining the systematics of past isotope variation and providing context for extended sediment records from the lake which will provide longer term palaeoclimate reconstructions covering multiple glacial interglacial cycles

the modern and last glacial maximum hydrological cycles of the eastern mediterranean and the levant from a water isotope perspective abstract the isotopic composition of precipitation p is one of the most widely used and informative terrestrial paleoclimate proxies p integrates a series of hydrological processes therefore any interpretation of paleohydrology using p requires a thorough understanding and quantification of the full hydrological cycle in this paper we use modern data to analytically model the full isotopic hydrological cycle of the eastern mediterranean and the southern levant including oceanic evaporation distillation during transport and precipitation over land this model allows us to determine the important factors controlling this system the model results underscore the significance of the isotopic distillation process driven by the land sea temperature gradient as a significant factor controlling the long term average isotopic composition of precipitation across israel based on the understanding of the processes that govern the modern system we model the isotopic composition of precipitation from the last glacial maximum lgm using published data for speleothem oxygen isotopes in calcite oxygen and hydrogen isotopes in fluid inclusions and clumped isotope values from soreq cave and the isotopic composition of east mediterranean planktonic foraminifera g ruber the data and model results indicate two plausible scenarios for the lgm that entail changes in the magnitude of distillation over israel in normalized humidity over the mediterranean and possible shifts of the moisture trajectories over the mediterranean the results presented in the paper illustrate the importance of understanding the full local hydrological cycle when reconstructing and interpreting the isotopic composition of precipitation

lithological mapping of the troodos ophiolite cyprus using airborne lidar topographic data traditional field based lithological mapping can be a time consuming costly and challenging endeavour when large areas need to be investigated where terrain is remote and difficult to access and where the geology is highly variable over short distances consequently rock units are often mapped at coarse scales resulting in lithological maps that have generalised contacts which in many cases are inaccurately located remote sensing data such as aerial photographs and satellite imagery are commonly incorporated into geological mapping programmes to obtain geological information that is best revealed by overhead perspectives however spatial and spectral limitations of the imagery and dense vegetation cover can limit the utility of traditional remote sensing products the advent of airborne light detection and ranging lidar as a remote sensing tool offers the potential to provide a novel solution to these problems because accurate and high resolution topographic data can be acquired in either forested or non forested terrain allowing discrimination of individual rock types that typically have distinct topographic characteristics this study assesses the efficacy of airborne lidar as a tool for detailed lithological mapping in the upper section of the troodos ophiolite cyprus morphometric variables including slope curvature and surface roughness were derived from a 4 m digital terrain model in order to quantify the topographic characteristics of four principal lithologies found in the area an artificial neural network the kohonen self organizing map was then employed to classify the lithological units based upon these variables the algorithm presented here was used to generate a detailed lithological map which defines lithological contacts much more accurately than the best existing geological map in addition a separate map of classification uncertainty highlights potential follow up targets for ground based verification the results of this study demonstrate the significant potential of airborne lidar for lithological discrimination and rapid generation of detailed lithological maps as a contribution to conventional geological mapping programmes

the great march 25 1998 antarctic plate earthquake moment tensor and rupture history we use broadband body and mantle wave data to study the 1998 antarctic intraplate earthquake the centroid moment tensor cmt has a large non double couple component there exist two pure double couple constrained solutions that fit the data almost equally well the frequent practice of taking the best double couple gives a far from optimal solution we use p and sh body waves to determine the rupture parameters of the first and larger of the two observed subevents the best rupture plane with strike 96 dip 69 and rake 18 is compatible with only one of the two cmt solutions strike 96 dip 64 rake 23 centroid location 63 1 s 148 4 e 10 km depth centroid time 0313 02 ut and m0 1 3 1021 n m mw 8 0 the first subevent is a simple primarily westward propagating 140 km rupture of 45 s duration with average velocity 3 km s 1 it has a seismic moment of 1 2 1021 n m mw 8 0 with 75 of its moment released between 10 and 27 s and a stress drop of 240 bars the rupture is physically bounded by two fracture zones at 147 5 e and 150 e the second subevent lasted from 70 to 90 s on a fault extending from 210 to 270 km west of the epicenter with a moment of 0 3 0 6 1021 n m mw 7 6 7 8 this is a spectacular example of dynamic stress triggering over a 100 km separation distance with a time delay of 40 s the complex pattern of aftershocks is primarily controlled by preexisting fracture zones on the ocean floor

alpine evidence for atmospheric circulation patterns in europe during the last glacial maximum the configuration of alpine accumulation areas during the last glacial maximum lgm has been reconstructed using glacial geological mapping the results indicate that the lgm ice surface consisted of at least three major ice domes all located south of the principal weather divide of the alps this implies that the buildup of the main alpine ice cover during oxygen isotope stage ois 2 was related to precipitation by dominant southerly atmospheric circulation in contrast to today s prevalent westerly airflow such a reorganization of the atmospheric circulation is consistent with a southward displacement of the oceanic polar front in the north atlantic and of the associated storm track to the south of the alps these results combined with additional paleoclimate records from western and southern europe allow an interpretation of the asynchronous evolution of the different european ice caps during the last glaciation 18o stages ois 4 and 3 were characterized by location of the polar front north of 46 n gulf of biscay this affected prevailing westerly circulation and thus ice buildup in western scandinavia the pyrenees vosges and northern alps at the lgm however the polar front lay at 44 n causing dominating southerly circulation and reduced precipitation in central and northern europe

the march 25 1998 antarctic plate earthquake the march 25 1998 antarctic plate earthquake mw 8 1 occurred 250 km from the nearest plate boundary in oceanic lithosphere with an age of 35 55 my analysis of aftershock patterns shows that the earthquake ruptured a fault or series of strike slip fault segments nearly 300 km long the strike of the fault s is nearly perpendicular to the north south trending fossil fracture zones which are the most marked bathymetric features of this region moment release during the mainshock was concentrated in two large subevents clearly visible in the teleseismic body wave waveforms modeling of these body waves using a finite fault source places the first of the two subevents near the point of rupture initiation on the eastern end of the fault with the second large subevent occurring 220 280 km to the west the two pulses of moment release are found to be separated in time by 65 s comparison of the relative s wave amplitudes of the first and second pulses suggests that a rotation of the focal mechanism by 10 occurred between the two subevents

the effectiveness of hillshade maps and expert knowledge in mapping old deep seated landslides large deep seated landslides with a shear surface deeper than 3 m and a mean affected area of 4 2 ha are common features in the flemish ardennes none of these deep seated landslides are dated but they are assumed to be rather old 100 years because most of these landslides are located under forest aerial photo interpretation commonly used for the creation of landslide inventories is not a suitable tool to map the landslides in the flemish ardennes therefore an intensive 100 day field survey was carried out by two geomorphologists in a 430 km 2 study area this resulted in a landslide inventory map indicating the location of 135 large deep seated landslides but field surveys are time consuming and thus very expensive therefore a cheaper and faster mapping technique was tested a hillshade map was constructed for the study area in a gis idris132 from a 5 m resolution digital elevation model dem seven experts were given 1 h to indicate all the hillslope sections which they suspected to be possible landslides on a copy of the aforementioned map scale 1 100 000 in total this exercise took only 1 day i e 7 person hours large differences in the number of presumed landslides and the extent of the hillslopes thought to be affected by landslides were reported among the seven experts the polygon and pixel efficiency were introduced to estimate the quality of the landslide maps based on hillshade maps and expert knowledge compared to the field survey based landslide inventory the quality of the landslide inventories based on the hillshade maps and expert knowledge was relatively low experts familiar with the study area obtained somewhat better results than experts who visited the study area only once a combination of the seven expert maps did not result in a good inventory map because too many unaffected hillslopes were incorrectly indicated as affected by landslides the results obtained in this study are comparable to an investigation carried out by wills c j mccrink t p 2002 comparing landslide inventories the map depends on the method environmental and engineering geoscience 8 279 293 although the tested method can never replace a detailed field survey taking into account the proposed improvements it can be used for the creation of a regional inventory map of old landslides in a densely forested area where light detection and ranging lidar data are unavailable c 2004 elsevier b v all rights reserved

climatic variability during the last 90 ka of the southern and northern levantine basin as evident from marine records and speleothems abstract the influence of the northern atlantic and tropical monsoonal systems as recorded by the river nile on the climate variability of the southeastern mediterranean was studied in two cores taken by the r v marion dufresne one core taken se of cyprus representing the northern levantine basin core 9501 980 m water depth and the other located 380 km further south represents the southeastern levantine basin in an area influenced by the river nile plume core 9509 884 m water depth the study was performed at relatively high resolution using several proxies 18o of globigerinoides ruber sediment characteristics and index colour parameters in core sections representing the last 86 ka a low resolution alkenone sea surface temperature record was also measured the time frame in both cores was mostly constrained by wiggle matching with the nearby well dated 18o and 13c record of the soreq cave which is mainly influenced by the eastern mediterranean water vapor the sedimentary record of the southern core is strongly influenced by the river nile contribution throughout the last 86 ka as evidenced by the higher sedimentation rates compared with the northern core 20 cm ka vs 5 cm ka continuously darker sediment colour and higher toc values 0 6 0 9 vs 0 25 wt not including sapropels during sapropels s1 and s3 present in both cores the influence of the river nile became more widespread reaching as far as cyprus yet the influence of the river nile remained stronger in the south as evident by the higher toc values in the southern core throughout the entire 90 ka period and the longer duration of s1 in the southern core an anomalous low 18o interval that is not recorded in western mediterranean occurred between 58 and 49 ka in the levantine basin and is more developed in the northern core this period correlates with d o interstadial 14 and maximum northern hemisphere insolation during the lastglacial cycle suggesting that the warming mainly impacted the northern levant the eastern mediterranean sea and land area was considerably warmer than the western mediterranean throughout the lgm holocene transition and the 18og ruber drop of 4 5 is significantly greater than the 3 shift found for the western mediterranean 18og bulloides both differences reflecting an increased continental effect from the western to eastern mediterranean comparison between the marine and the land 18o records suggests that the origin of rain over the land is composed of mixed signal from the southern and northern levantine basin the study of 18osea land variations demonstrates that various factors have influenced the sea land relationship during the last 90 ka the amount effect has an important influence on rainfall 18o during interglacial periods particularly sapropel periods whereas during glacial periods increased land distances and elevation differences arising from decrease in sea level may have brought about decrease in 18o of rainfall due to rayleigh distillation processes these influences were superimposed on those of sea surface water 18o changes brought about by continental ice melting and the strong effects felt in the southern levantine basin of the high river nile input during periods of enhanced monsoonal activity

accounting for kinetic isotope effects in soreq cave israel speleothems abstract there is growing evidence that speleothem calcite grows out of isotopic equilibrium with cave drip water with clumped isotope analysis providing a sensitive indicator for disequilibrium this disequilibrium is primarily the result of co2 degassing from a thin film of water leading to irreversible 13c enrichment and reversible 18o enrichment and 47 depletion here we examine isotopic disequilibrium in soreq cave israel using multiple modern day and late holocene speleothems the variability observed in 47 is small within the analytical uncertainty but the 47 derived temperature is offset from the modern cave temperature by 4 c reflecting degassing related disequilibrium that is fairly constant spatially 18o is more heterogeneous reflecting short term variability in drip water 18ow combined with variability in the speleothem growth rates and related fractionation between dissolved carbonate species and the growing calcite mineral this complexity however is markedly reduced by spatial or temporal averaging enabling an interpretation of the cave paleoclimate record we examine the soreq cave speleothems through a comparison with 2 types of thermometers one is based on caco3 precipitation from a bulk solution and is typically used for calibration of the 47 and 18o thermometers a second that is based on caco3 precipitating at the surface of the solution thus focusing and amplifying the thin film characteristics of speleothem formation soreq cave speleothems are intermediate between these thermometers providing a cave specific thermometer calibration

dynamic stress variations due to shear faults in a plane layered medium summary a complete set of expressions is presented for the computation of elastic dynamic stress in plane layered media we use a discrete wavenumber reflectivity method to compute the stress field radiated by arbitrary moment tensor sources the expressions derived here represent an interesting tool for both the observational and theoretical analysis of dynamic stress changes associated with earthquake phenomena dynamic stress changes associated with a strike slip fault having unilateral rupture are shown this modelling which is similar to the 1992 landers california earthquake illustrates the effects of distance directivity and depth on transient stress changes

cosmo skymed and terrasar x datasets for geomorphological mapping in the eastern of marajo island amazon coast abstract the amazon coast is marked by the high discharge of sediments and freshwater macrotidal influence a wide continental shelf extensive flood plains and lowered plateaus which make it unique as a delta and estuary landscape further the tropical climate imposes heavy rains and incessant cloudiness that render microwave systems more suitable for cartography this study proposed to recognize and map the amazon coastal environments through the x band synthetic aperture radar provided by cosmo skymed csk and terrasar x tsx systems the sar datasets consisted of interferometric and stereo pairs restricted to single revisit and obtained with small interval 1 11 days under steeper 0 60 during the rainy and dry season showing more suitability for radargrammetry on the amazon coast the rf models resulted in kappa coefficient between 0 39 to 0 70 indicating that the use of x band sar images at an incidence angle greater than 44 and obtained in the dry season is more appropriated for the morphological mapping the rf models given by tsx achieved the higher mapping accuracies per scenario of sar products in order of 0 48 to 0 63 despite this the best classification was carried out by 19 rf model with 0 70 provided by csk in shallow incidence composed by intensity texture coherence and stereo dsm the csk and tsx data allowed to map the amazon coast precisely based on x band at single polarization high spatial resolution and revisit which has demonstrated the support for detailed cartography scale 1 50 000 and frequent updating monthly up to yearly

geochemical characterization of contemporary fine detritus in the dead sea watershed abstract reconstruction of paleo synoptic conditions e g past atmospheric circulation involves tracing the origins and routes of transport of particles comprising eolian archives i e desert dust lacustrine deposits that accumulated in the quaternary lakes filling the dead sea basin include remobilized eolian desert dust that was washed to the lakes by floods here we analyze the mineralogical chemical compositions e g mg al ratios and 87sr 86sr and 143nd 144nd end values isotope ratios of fine siliciclastic particles that form the modern surface cover of the dead sea watershed e g loess mountain soils and flood particles that are mobilized to the lake during distinct synoptic conditions the data comprises reference data set that can be used for paleo synoptic interpretation enhancing our ability to decipher the paleoclimate history during the quaternary in the levant the end values and 87sr 86sr ratios of the fine detritus lie between 8 and 6 and 0 7035 to 0 7188 reflecting the values of erosional products of granitoids that are exposed in the sahara and arabia deserts and the unradiogenic sr from local soils in the dead sea watershed particles with low mg al ratios i e 0 17 0 31 are transported by the western winds associated with the mediterranean cyclones transporting dust from the sahara while particles with high mg al ratios 0 27 0 68 are associated with storms blowing dusts from east to the dead sea watershed saudi arabia and syrian deserts during red sea trough synoptic conditions fine particles blown from the sahara deserts during winter storms are rapidly washed to the lake by subsequent floods whereas the particles blown during dry storms associated with red sea trough synoptic conditions accumulate on the surface of the dead sea watershed and can be washed later to the lake during extensive rain events

rainfall recharge relationships within a karstic terrain in the eastern mediterranean semi arid region israel δ 18o and δd characteristics annual rainfall variations and processes in the upper vadose zone exert a profound influence on the chemical and isotopic compositions of waters of carbonate aquifers in semi arid climatic zones in order to define these processes we have studied the surface temperatures during rainfall events the isotopic composition of rain infiltrating and groundwaters this study was carried out within a karstic terrain soreq cave israel located in cenomanian dolomitic rocks approximately 40 km inland of the mediterranean sea and 400 m above sea level the climate is typical of the eastern mediterranean semi arid conditions with a rainy winter and dry summer and the average annual rainfall in the area is 500 mm close monitoring indicates that the d and 18o values of individual rainstorm events decrease with increasing rainfall annual average isotopic values of years with rainfall of 500 600 mm do not vary systematically years with extreme rainfall values define a negative covariation between the 18o and rainfall the d 18o relationship of all rain events of more than 20 mm fall on the mediterranean meteoric water line mmwl with a slope of 8 and d excesses of 20 30 these rain events occur when mid winter surface temperatures are 5 to 10 c rainfall events of less than 20 mm mainly occurring at above 10 c have slopes of less than 8 and smaller d excess as a consequence of evaporation processes beneath the clouds two main water types infiltrating into the cave are recognized slow and fast drip slow drip occurs from the tips of stalactites and takes place throughout the year these waters represent seepage water that remains in the upper vadose zone for up to several decades fast drip emanates from fissures in the cave roof during the winter seasons these waters represent vadose flow with a short residence time of less than 1 year the infiltration of the fast drip water into the cave depends on the fracture system of the rock cover and on the intensity of the rainstorms in the inner parts of the cave where the rock cover is thick fast drip starts only after several massive 20 mm rainstorms whereas below a thin roof the response time of fast drip is a few hours to a few days after intensive rainstorms both fast and slow drip water fall on the mmwl indicating that they are derived mainly from the relatively intensive rainstorms that compose about 23 of the annual rainfall although fast dri water represents massive rainstorms their 18o and d values are nonetheless higher by 1 and 10 respectively relative to the average rainwater compisition this indicates that the fast drip water consists predominantly of water derived from intensive rainstorms admixed with a minor component of isotopically 18o and d enriched water which is represented by the slow drip waters the fast drip waters are derived mainly from massive rain events at surface temperatures of 5 to 10 c which thermally equilibrate with the host rock and upon reaching the cave they have already acquired the mean temperature 20 c of the cave

seasonal climate signals 1990 2008 in a modern soreq cave stalagmite as revealed by high resolution geochemical analysis article high resolution isotopic and geochemical analyses in a modern 1990 2008 soreq cave stalagmite are com pared to instrumental records of rainfall and dripwater from the cave with the aim of determining how seasonal resolutionclimateinformationistransmittedtospeleothemgeochemistry insitu micron scaleanalysis of oxygen isotope ratios 18 o and trace elements by ion microprobe in combination with a continuous linear traverse of trace element concentrations by laser ablation icp ms la icp ms allow the definition of geochem ical pathways within the cave fluorescent banding imaged by confocal laser fluorescent microscopy clfm as well as

dynamic stress triggering during the great 25 march 1998 antarctic plate earthquake we investigate the coseismic stress redistribution during the 25 march 1998 great antarctic plate mw 8 1 earthquake in which the mainshock consisted of two distinct subevents separated in time by several tens of seconds we compute the dynamic stress time histories for the fault geometry and the rupture and slip history determined by henry et al 2000 using the discrete wavenumber and re flectivity method of cotton and coutant 1997 both for a homogeneous and a strat ified half space we first image the coseismic stress evolution caused by the first subevent on the fault plane of the second one for both the velocity models we compute both shear and normal stress changes and a time dependent coulomb failure function cff our results show that the shear stress changes have larger amplitudes than the other stress components and hence are the primary control on the evolution of the cff the dynamic stress amplitudes are larger than the static stress pertur bations with the largest positive dynamic stress peak on the second subevent fault plane reaching slightly less than 0 2 mpa at 60 sec and 65 sec after the nucleation for the layered and the homogeneous crustal models respectively we suggest that the dynamic stress changes caused by the first subevent promoted a nearly instan taneous failure on the second subevent fault

characterizing arid region alluvial fan surface roughness with airborne laser swath mapping digital topographic data 1 range front alluvial fan deposition in arid environments is episodic and results in multiple fan surfaces and ages these distinct landforms are often defined by descriptions of their surface morphology desert varnish accumulation clast rubification desert pavement formation soil development and stratigraphy although quantifying surface roughness differences between alluvial fan units has proven to be difficult in the past high resolution airborne laser swath mapping alsm digital topographic data are now providing researchers with an opportunity to study topography in unprecedented detail here we use alsm data to calculate surface roughness on two alluvial fans in northern death valley california we define surface roughness as the standard deviation of slope in a 5 m by 5 m moving window comparison of surface roughness values between mapped fan surfaces shows that each unit is statistically unique at the 99 confidence level furthermore there is an obvious smoothing trend from the presently active channel to a deposit with cosmogenic 10be and 36cl surface exposure ages of 70 ka beyond 70 ka alluvial landforms become progressively rougher with age these data suggest that alluvial fans in arid regions smooth out with time until a threshold is crossed where roughness increases at greater wavelength with age as a result of surface runoff and headward tributary incision into the oldest surfaces

machine learning predicts reach scale channel types from coarse scale geospatial data in a large river basin author s guillon herva byrne colin f lane belize a sandoval solis samuel pasternack gregory b

transient triggering of near and distant earthquakes we demonstrate qualitatively that frictional instability theory provides a context for understanding how earthquakes may be triggered by transient loads associated with seismic waves from near and distance earthquakes we assume that earthquake triggering is a stick slip process and test two hypotheses about the effect of transients on the timing of instabilities using a simple spring slider model and a rate and state dependent friction constitutive law a critical triggering threshold is implicit in such a model formulation our first hypothesis is that transient loads lead to clock advances i e transients hasten the time of earthquakes that would have happened eventually due to constant background loading alone modeling results demonstrate that transient loads do lead to clock advances and that the triggered instabilities may occur after the transient has ceased i e triggering may be delayed these simple clock advance models predict complex relationships between the triggering delay the clock advance and the transient characteristics the triggering delay and the degree of clock advance both depend nonlinearly on when in the earthquake cycle the transient load is applied this implies that the stress required to bring about failure does not depend linearly on loading time even when the fault is loaded at a constant rate the timing of instability also depends nonlinearly on the transient loading rate faster rates more rapidly hastening instability this implies that higher frequency and or longer duration seismic waves should increase the amount of clock advance these modeling results and simple calculations suggest that near tens of kilometers small moderate earthquakes and remote thousands of kilometers earthquakes with magnitudes 2 to 3 units larger may be equally effective at triggering seismicity our second hypothesis is that some triggered seismicity represents earthquakes that would not have happened without the transient load i e accumulated strain energy would have been relieved via other mechanisms we test this using two new seismicity models that 1 are inherently unstable but slide at steady state conditions under the background load and 2 are conditionally stable such that instability occurs only for sufficiently large perturbations for the new seismicity models very small amplitude transients trigger instability relative to the clock advance models the unstable steady state models predict that the triggering delay depends inversely and nonlinearly on the transient amplitude as in the clock advance models we were unable to generate delayed triggering with conditionally stable models for both new seismicity models the potential for triggering is independent of when the transient load is applied or equivalently of the prestress unlike in the clock advance models in these models a critical triggering threshold appears to be inversely proportional to frequency further advancement of our understanding will require more sophisticated quantitative models and observations that distinguish between our qualitative yet distinctly different model predictions

compound rupture of the great 1998 antarctic plate earthquake the march 25 1998 antarctic plate earthquake ruptured a portion of the antarctic plate more than 200 km west of its boundary with the australian plate the harvard centroid moment tensor solution indicates that the earthquake was primarily a strike slip event but the large non double couple component of the moment tensor suggests considerable complexity in the rupture process we use a finite fault inversion method to determine details of the rupture process from teleseismic body waves recorded by the global seismic network the p waves are poorly fit by one or more subevents having only a strike slip mechanism we find that the presence of a large oblique normal faulting subevent located to the east of the hypocenter is necessary to improve the fit this subevent combines with a larger strike slip subevent to the west to comprise the main moment release in the earthquake and is the cause of the large non double couple component in the long period focal mechanism the earthquake exhibited very high slip and high stress drop compared with most interplate strike slip events and the rupture was largely confined to the upper 15 20 km of the lithosphere both constituent focal mechanisms indicate that this part of the antarctic plate is under nw se oriented tension although the origin of these stresses is unknown

digital terrain modeling abstract this article examines how the methods and data sources used to generate dems and calculate land surface parameters have changed over the past 25 years the primary goal is to describe the state of the art for a typical digital terrain modeling workflow that starts with data capture continues with data preprocessing and dem generation and concludes with the calculation of one or more primary and secondary land surface parameters the article first describes some of ways in which lidar and radar remote sensing technologies have transformed the sources and methods for capturing elevation data it next discusses the need for and various methods that are currently used to preprocess dems along with some of the challenges that confront those who tackle these tasks the bulk of the article describes some of the subtleties involved in calculating the primary land surface parameters that are derived directly from dems without additional inputs and the two sets of secondary land surface parameters that are commonly used to model solar radiation and the accompanying interactions between the land surface and the atmosphere on the one hand and water flow and related surface processes on the other it concludes with a discussion of the various kinds of errors that are embedded in dems how these may be propagated and carried forward in calculating various land surface parameters and the consequences of this state of affairs for the modern terrain analyst

constraints on hydrological and paleotemperature variations in the eastern mediterranean region in the last 140 ka given by the δd values of speleothem fluid inclusions abstract speleothem fluid inclusions potentially provide vital data on the paleohydrological conditions in glacial and interglacial periods we show here that d analyses of fluid inclusions from speleothems in three caves in the eastern mediterranean region israel provide a basis for understanding hydrological and temperature variations in the last 140 ka using measured d fluid inclusion values and temperature ranges constrained by the present day mediterranean meteoric water line mmwl and the global mwl we show a strong compatibility between the land and marine temperature records with the highest land temperatures occurring at 120 130 ka 17 22 c and the present 18 c and the lowest temperatures during the lgm about 10 c lower than present interglacial waters are constrained to follow the mmwl and most glacial waters also plot close to the mmwl with a slight shift towards the mwl however during two remarkable brief periods at the termination of the lgm the waters plot on the mwl suggesting that both sharp cooling and an increase in relative humidity above the em sea reduced d excess values to those of the global system

the eastern mediterranean paleoclimate as a reflection of regional events soreq cave israel the climate of the eastern mediterranean region of the last 60 ky was determined by a high resolution study of the oxygen and carbon isotopic composition 1500 measurement pairs of speleothems from the soreq cave israel with chronology provided by 53 precise 230 th 234 u tims ages the high precision of the speleothem tims ages permits us to determine the timing of regional climatic events in the eastern mediterranean region and to see if they correlate with global events during the period from 60 to 17 ky the 18 o and 13 c values were generally 2 2 5 higher than during the period from 17 ky to present this is consistent with the climatic transition from glacial to interglacial within the 60 to 17 ky period the soreq cave stable isotope profile includes four cold peaks at 46 35 25 and 19 ky and 2 warm peaks at 54 and 36 ky in addition the period 17 ky has two more cold peaks at 16 5 and from 13 2 to 11 4 ky the ages of four of the six cold peaks correlate well with the ages of three heinrich events h1 h2 h5 and with the age of the younger dryas however the other two heinrich events are not reflected in the soreq cave record several other isotope peaks which appear during the last 7 ky are contemporaneous with regional climatic events in the middle east and north africa in addition to the drop in 18 o and 13 c observed between the last glacial and the holocene sharp simultaneous drops in 234 u 238 u 0 ratios sr concentrations and in 87 sr 86 sr are also observed suggesting that the latter are climate related these variations are interpreted in terms of major changes in the temperature the mean annual rainfall and its isotopic composition the isotopic composition of the mediterranean vapor source the soil moisture conditions and in the mixing proportions of sources with different 87 sr 86 sr ratios sea spray dust particles and dolomitic host rock

using textural analysis for regional landform and landscape mapping eastern guiana shield availability of digital elevation models dem of increased spatial resolution has triggered interest in texture based methods for automated geomorphometry this prospect is all the more appealing concerning tropical countries for which mapping of geomorphic entities has remained limited despite its relevance for natural resource assessment and land planning in this paper we applied to the shuttle radar topography mission srtm dem a multiscale texture analysis based on fourier 2d periodogram foto method to reach a spatially coherent mapping that would agree with current knowledge over the conterminous territories of french guiana and amapa brazil through a principal component analysis foto extracted textural features were found complementary and combined with six common physiographic criteria convexity wetness index dissection elevation and percent of steep and low slopes calculated from the dem this provided a primary semiautomated mapping of 16 classes of landform types to increase legibility we aggregated into eight landscape unit classes that were the most similar in terms of texture and relief criteria while being frequently contiguous the resulting map was compared with existing maps that were however more local or of lesser resolution and informative content over the region of interest multiscale fourier spectra proved useful to depict land surface texture and in synergy with relief variables allowed identifying a large variety of landforms for broad scale geomorphic mapping in the humid tropics

a unified model for dynamic and static stress triggering of aftershocks antishocks remote seismicity creep events and multisegmented rupture aftershocks have been thought to be triggered by static stress transfer the 1992 landers and 1999 hector mine california earthquakes have demonstrated the possibility of remote triggering of seismicity highlighting the role of dynamic seismic waves static stress changes and transient deformations have different timescales the mechanisms by which they trigger earthquakes are thought to be different leading to an unwieldy vision of aftershock triggering we propose a model that encompasses both static and dynamic triggering of aftershocks and antishocks as well as the occurrence of stable slip creep events or multisegmented rupture the framework of this model is based on the stability instability transition of faults we propose that dynamic and static stress triggering pertain to the same physical process we study the effect of the complete coulomb failure function we demonstrate the possibility of the triggering of seismicity by a dynamic stress pulse in a stress shadow zone characterized by a negative static stress field the limited time efficiency of dynamic triggering shown by the data is explained by the model we suggest that dynamic waves trigger only the most unstable faults associated with a relatively short characteristic time while the static stress field triggers also faults that are stable associated with a larger characteristic time

last glacial warm events on mount hermon the southern extension of the alpine karst range of the east mediterranean abstract this study focuses on warm last glacial episodes in the southernmost extension of the alpine karst range of the eastern mediterranean levant region through the study speleothems in mizpe shelagim cave located in mt hermon the alpine karst range extends from turkey through syria and lebanon reaching its southern limit in mt hermon at an elevation of more than 2000 m under present day conditions southern mt hermon receives 1000 2000 mm precipitation mostly as snow that originates in the eastern mediterranean sea speleothems deposition in this high altitude region was continuous during interglacials but during the last glacial growth only occurred when average annual temperatures exceeded 3 c as inferred from the study of speleothem fluid inclusions warming episodes occurred at 65 ka 56 ka 54 5 ka 52 5 51 ka 49 ka 42 ka and 36 ka and are coincident with maximum insolation at 65 n the main depositional period from 56 ka to 51 ka coincides with dansgaard oeschger interstadial 15 and 14 and warming in the northeastern basin of the mediterranean sea warming in the southern alpine karst range of the eastern mediterranean was manifested by vegetation development together with significant snow melting that resulted in the drainage of large amount of water to the dead sea rift valley

characterization of volcanic geomorphology and geology by slope and topographic openness abstract we used a digital elevation model dem of iwate volcano japan to calculate slope and topographic openness for every geological unit in that area further we conducted principal component analysis pca and stepwise discriminant analysis sda to evaluate statistical differences in the morphometric parameters of the geological units we categorized the geological units according to their ages and their formation processes the categorization based on formation processes was as follows lava flow lava central cone stratocone air fall deposit pyroclastic flow deposit volcanic fan deposit and debris avalanche deposit pca allowed us to select geological units suitable for analysis while sda was used to select some morphometric parameters which could explain the differences in the formation processes and ages of the geological units we found that the formation processes correspond well to mean slope and that the geological ages that control the degree of surface dissection correspond well to the standard deviations of slope and negative topographic openness

hand a new terrain descriptor using srtm dem mapping terra firme rainforest environments in amazonia optical imagery can reveal spectral properties of forest canopy which rarely allows for finding accurate correspondence of canopy features with soils and hydrology in amazonia non floodable swampy forests can not be easily distinguished from non floodable terra firme forests using just bidimensional spectral data accurate topographic data are required for the understanding of land surface processes at finer scales topographic detail has now become available with the shuttle radar topographic mission srtm data this new digital elevation model dem shows the feature rich relief of lowland rain forests adding to the ability to map rain forest environments through many quantitative terrain descriptors in this paper we report on the development of a new quantitative topographic algorithm called hand height above the nearest drainage based on srtm dem data we tested the hand descriptor for a groundwater topographic and vegetation dataset from central amazonia the application of the hand descriptor in terrain classification revealed strong correlation between soil water conditions like classes of water table depth and topography this correlation obeys the physical principle of soil draining potential or relative vertical distance to drainage which can be detected remotely through the topography of the vegetation canopy found in the srtm dem data

chinese stalagmite δ 18 o controlled by changes in the indian monsoon during a simulated heinrich event carbonate cave deposits in india and china are assumed to record the intensity of monsoon precipitation because the 18 o of the carbonate tracks the isotopic signature of precipitation these records show spatially coherent variability throughout the last ice age and suggest that monsoon strength was altered during the millennial scale climate variations known as dansgaard oeschger events and during the heinrich cooling events here we use a numerical climate model with an embedded oxygen isotope model to assess what caused the shifts in the oxygen isotope signature of precipitation during a climate perturbation designed to mimic a heinrich event our simulations show that a sudden increase in north atlantic sea ice extent during the last glacial period leads to cooling in the northern hemisphere reduced precipitation over the indian basin and weakening of the indian monsoon the precipitation is isotopically heavier over india and the water vapour exported to china is isotopically enriched our model broadly reproduces the enrichment of 18 o over northern india and east asia evident in speleothem records during heinrich events we therefore conclude that changes in the 18 o of cave carbonates associated with heinrich events reflect changes in the intensity of indian rather than east asian monsoon precipitation