a new attenuation relation for strong ground motion in japan based on recorded data following the 1995 hyogo ken nanbu kobe earthquake the japanese government in an effort to prevent future earthquake disasters installed networks consisting of a large number of strong motion observation stations further national seismic hazard maps were made available to the public on an internet website in march 2005 by the headquarters for earthquake research promotion however these maps indicate only the local seismic intensity for japan as empirically con verted from predicted peak velocity in consolidated soils for various applications other strong motion indexes such as the response spectral acceleration are required in this study a database of whole japanese strong ground motion records between 1963 and 2003 is established in order to identify a new standard attenuation relation for japan for response acceleration as well as peak value it is usually very difficult to determine a suitable model form due to the large variability of strong motion data and correlation among the model variables because the strong coupling of variables in an attenuation model and the statistical power of the data is often not large enough to determine the necessity of these parameters therefore in this study our model has only three variables earthquake magnitude shortest distance to the seismic fault plane and focal depth to improve predictions given by the model site correction terms are adopted and additional terms for correcting regional anomalous seismic intensity with respect to the base model are determined the good fit between the model and observed strong motion records suggests that the new model is reasonably robust

land sea interaction and morphogenesis of coastal foredunes a modeling case study from the southern baltic sea coast abstract coastal foredunes are developed as a result of the interplay of multi scale land sea processes basic driving mechanisms of coastal foredune morphogenesis as well as natural processes and factors involved in shaping the foredune geometry are quantitatively studied in this paper by a numerical model aeolian sediment transport and vegetation growth on the subaerial part of a beach is simulated by a cellular automata ca approach while the sediment budget in the subaqueous zone serving as a sediment source sink for the foredune ridges is estimated in a process based model the coupled model is applied to a 1 km long section of a barrier coast swina gate in the southern baltic sea for a 61 year 1951 2012 hindcast of its foredune development general consistency is shown between the observational data and simulation results indicating that the formation of an established coastal foredune results from a balance between wind wave impacts and vegetation growth driven by an effective onshore wind and a boundary sediment supply small scale dunes develop on the backshore and migrate landward they are then trapped in a narrow strip characterized by a large density gradient of vegetation cover which separates the hydrodynamically active zone and the vegetated zone continuous accumulation of sediment in this strip induces the development of a foredune ridge according to the simulations the formation of an established coastal foredune has to meet three preconditions 1 an effective onshore aeolian transport 2 a net onshore or lateral sediment supply and 3 a climate favoring vegetation growth the formation of a new foredune ridge in front of an already existing foredune is determined by a combination of the sediment supply rate the extreme wind wave event frequency and the vegetation growth rate simulation results demonstrate a remarkable variability in foredune development even along a small 1 km coast section implying that the medium to long term land sea interaction and foredune morphogenesis is quite sensitive to boundary conditions and various processes acting on multi temporal and spatial scales

decadal scale morphologic variability of managed coastal dunes coastal dunes located in densely populated areas provide various services to man such as protection against flooding during storm surges since coastal dunes are dynamic features the level of protection they provide varies in time therefore management interventions are often undertaken to stabilize the dunes to reduce the natural variability this study provides quantitative insight into the morphologic variability of managed foredunes over time spans of decades we used empirical orthogonal function eof analysis on a 45 year data set of annually surveyed dune profiles along 97 km of the netherlands coast on average 70 of the deviations from the time averaged profiles could be related to cross shore coherent changes in foredune shape as mapped onto eof 1 these changes are often largely due to morphologic developments occurring near the dunefoot changes in dune shape were coherent over time as well as in the longshore direction albeit with different characteristic patterns along the coast these results show that managed foredunes may still exhibit considerable morphologic variability that should not be ignored in long term dune safety assessment studies

a new look at evidence for a wadati benioff zone and active convergence at the north panama deformed belt the nature of the northern boundary of the panama microplate often referred to as the north panama deformed belt npdb has been the subject of much speculation previous studies have used a variety of data including teleseismic gravity bathymetric marine magnetic and field studies of uplift and tsunami deposits as well as modified mercalli intensity distributions from historic earthquakes to reveal the nature of the npdb data have been collected for over 30 yrs and yet the character of the npdb remains unclear current analyses and interpretation provide a number of mutually exclusive options and much controversy in this article we examine local and regional seismicity combined with teleseismic observations and historic earthquake data to present an alternative analysis for the npdb using small earthquakes recorded by a local network we image a well defined wadati benioff zone dipping southward beneath the panama microplate these data provide new evidence regarding the nature of panama microplate caribbean plate boundary kinematics and demonstrate the existence of an active subduction zone a more complete understanding of the nature of the seismicity and plate interactions along the npdb offshore panama including a subduction zone capable of producing earthquakes of m 7 should be included in future earthquake hazard assessments

selection of earthquake scaling relationships for seismic hazard analysis a fundamentally important but typically abbreviated component of seismic hazard analysis is the selection of earthquake scaling relationships these are typically regressions of historical earthquake datasets in which magnitude is estimated from parameters such as fault rupture length and area the mix of historical data from different tectonic environments and the different forms of the regression equations can result in large differences in magnitude estimates for a given fault rupture length or area we compile a worldwide set of regressions and make a first order shortlisting of regressions according to their relevance to a range of tectonic regimes plate tectonic setting and fault slip type in existence around the world regression relevance is based largely on the geographical distribution age and quantity quality of earthquake data used to develop them our compilation is limited to regressions of magnitude or seismic moment on fault rupture area or length and our shortlisted regressions show a large magnitude range up to a full magnitude unit for a given rupture length or area across the various tectonic regimes these large differences in magnitude estimates underline the importance of choosing regressions carefully for seismic hazard application in different tectonic environments

characterization of the heterogeneous source model of intraslab earthquakes toward strong ground motion prediction we characterize the heterogeneous source slip model of intraslab earthquakes to compare source scaling properties with those of inland crustal and subduction zone plate boundary earthquakes we extracted rupture area s total area of asperity s a average slip d and average slip on asperity d a of eleven intraslab earthquakes following the procedure proposed by somerville et al seism res lett 70 59 80 1999 and proposed the empirical scaling relationship formula of s s a and d for intraslab earthquakes under the same seismic moment an intraslab earthquake has a smaller rupture area and total area of asperity and smaller average slip than an inland crustal earthquake the area ratio of asperity area and total rupture area of intraslab earthquakes are similar to those of inland crustal earthquakes the strong motion generation area smga scaling of intraslab earthquakes appears self similar and those results support the idea the characterized source model of intraslab earthquakes can be modeled in a manner similar to that of inland crustal earthquakes

sand spit rhythmic development a potential record of wave climate variations arcay spit western coast of france abstract this study aims at showing the sedimentary and geomorphological records of wave climate variations by spits the studied spit arcay spit is located on the french atlantic coast and has displayed a rapid elongation since the beginning of the 19th century that potentially represents a two century long wave climate record wave climate and spit growth relationships are studied from two complementary methods 1 numerical modelling of wave and longshore transport temporal and spatial variabilities and 2 morphological monitoring based on the analysis of 4 historical maps 1811 1945 8 aerial photographs 1945 2000 and 17 satellite spot images 1987 2005 results at seasonal to interannual time scales show that the sand spit area gain variations are the result of variations in longshore transport themselves modulated mainly by wave height moreover energetic swells seem to cause massive sand accumulation and spit elongation whereas less energetic swells appear to be responsible for small sand accumulation and spit curvature at longer time scale decades to centuries increasing spit growth phases are also synchronised with periods of energetic swells or high storm surge frequency these results suggest that wave climate variations are the main factor controlling spit morphological evolutions

source spectral characteristics of two large intra slab earthquakes along the southern kurile hokkaido arc abstract in 1993 and 1994 two large earthquakes occurred along the southern kurile hokkaido arc the 1993 kushiro oki earthquake 15 january mw 7 6 and the 1994 shikotan earthquake 4 october mw 8 2 these were intra slab earthquakes that ruptured through a substantial part of the subducting oceanic lithosphere we study source spectral characteristics of these large intra slab earthquakes based on strong motion records for the kushiro oki earthquake the s wave spectra on three rock site stations are directly compared with the theoretical spectra based on the omega squared source model and the source parameters estimated from long period seismic waves the observed spectra are roughly consistent with the theoretical ones at low frequencies

late holocene post 4000 years bp coastal dune development in northumberland northeast england the recent environmental history of coastal dune systems in northumberland northeast england has been examined using geomorphological stratigraphical and sedimentological techniques linked to radiocarbon and infrared stimulated luminescence irsl dating stratigraphies were determined from 22 vibracores and three sections and dune chronology was based on 28 14 c dates from peat and soil organic horizons and 26 irsl dates on k feldspar grains from within sand layers almost all dune systems are associated with regressive shorelines consequent upon a fall in relative sea level rsl from its holocene peak and indicate rsl functioned as a macroscale control on dune development where dunes are anchored on terrestrial sediment dune expansion may have been either transgressive or regressive in nature where near shore marine sediments form the dune substrate a regressive prograding dune model seems most likely most dune building occurred during the little ice age lia probably in a

sand invasion along the portuguese coast forced by westerly shifts during cold climate events phases of higher aeolian activity are responsible for the formation and movement of large transgressive dunefields well reported phases of aeolian activity in northwest europe are coincident with global cooling events and were related to enhanced westerly winds and storminess however the extent to which these climatic episodes influenced dunefield dynamics in southwest europe remains an open question ground penetrating radar gpr was used to image the stratigraphy of a cliff top coastal transgressive dunefield in portugal and reconstruct former windfield regimes using optically stimulated luminescence osl five major phases of aeolian activity were dated at 12 6 5 6 1 2 0 4 and 0 3 ka and related to coastal instability and enhanced westerlies these phases were later reconciled to favorable patterns of atmospheric circulation simulated by global and regional climate models at both synoptic and local scales respectively the results prove that major phases of aeolian activity in southwest europe are associated with the onset of cold climate events of global distribution coinciding with aeolian accumulation in northwest europe this implies the dominance of zonal westerlies along the western coast of europe from denmark to portugal during the onset of cold climate events model simulations suggest that the pattern of atmospheric circulation during periods of enhanced aeolian activity is compatible with prolonged negative phases of the north atlantic oscillation nao

new gmpes for the sagami bay region in japan for moderate magnitude events with emphasis on differences on site amplifications at the seafloor and land seismic stations of k net

rupture process of the 1983 japan sea akita oki earthquake using a waveform inversion method the rupture process of the 1983 japan sea earthquake mjma 7 7 is determined by applying waveform inversion of displacement type strong motion records based on the bayesian method the synthesis of the seismic motions from the main shock is made using the records from the two aftershocks mjma 7 1 and mjma 6 1 as empirical green s functions the main shock fault consists of two subfaults the aftershock m 6 1 occurring south of the main shock fault is used for the southern subfault empirical green s function and the aftershock m 7 1 occurring north of the main shock fault is used for the northern subfault in this synthesis it is not necessary to calculate propagation path and local site effects therefore the information about the source process can be extracted from the comparison between observed seismic motions and the synthetic ones without detailed information on the velocity structure along the whole path from the source to each station the inversion for the rupture process is attempted for both a line source model and an area source model in both models the main shock fault surface is divided into several elements whose sizes are determined from the scaling relations between the main shock and its aftershocks the slip displacement and the rupture starting time on each element are estimated as model parameters in the inversion a good convergence is obtained after about 10 iteration steps for the line source case and after 5 iteration steps for the area source case the results are summarized 1 the average rupture velocity is approximately 2 5 km sec for the southern subfault and 2 0 km sec for the northern subfault and 2 there is a large slip displacement near the rupture initiation point and the north edge of the fault thus there is considerable heterogeneity in rupture propagation and slip distribution over the fault plane

optical dating of young coastal dunes on a decadal time scale we explore the use of quartz optically stimulated luminescence osl dating for reconstructing coastal evolution on a time scale of decades to a few hundred years samples are taken from the accretionary south west coast of texel a barrier island just offshore of the northern netherlands the ages of dune ridges are known from historical sources an excellent chronology with a decadal accuracy exists for the past 260 years osl ages of less than 10 years on the youngest samples indicate that the osl signal of the quartz grains is very well zeroed prior to deposition and burial osl ages of five samples from a 250 year old dune ridge are indistinguishable and the osl ages on 17 out of 20 samples are in excellent agreement with the well known independent age controls our results highlight the potential of osl dating for high resolution reconstruction of coastal evolution over the past few centuries

low abundance materials at the mars pathfinder landing site an investigation using spectral mixture analysis and related techniques abstract recalibrated and geometrically registered multispectral images from the imager for mars pathfinder imp were analyzed using spectral mixture analysis sma and related techniques sma models a multispectral image scene as a linear combination of endmember spectra and anomalous materials which do not fit the model are detected as model residuals while most of the imp data studied here are modeled generally well using bright dust gray rock and shade image endmembers additional anomalous materials were detected through careful analysis of root mean square rms error images resulting from sma for example analysis of sma fraction and rms images indicates spectral differences within a previously monolithologic dark soil class a type of dark soil that has high fractional abundances in rock fraction images gray rock soil was identified other anomalous materials identified included a previously noted black rock lithology a class of possibly indurated compacted or partially cemented soils intermediate soil and a unit referred to as anomalous patches on at least one rock the black rock lithology has a strong 900 1000 nm absorption and modeling of the derived image endmembers using a laboratory reference endmember modeling rem approach produced best fit model spectra that are most consistent with the presence of high ca pyroxenes and or olivine crystalline ferric oxide minerals or mixtures of these materials as important components of the black rock endmember more unique mineralogic identifications could not be obtained using our initial rem analyses both intermediate soil and anomalous patches units exhibit a relatively narrow 860 950 nm absorption that is consistent with the presence of either low ca pyroxenes or a cementing crystalline ferric oxide mineral

internal structure of the aeolian sand dunes of el fangar spit ebro delta tarragona spain this paper presents an analysis of the dune field dynamics of el fangar spit in the ebro delta spain associating it with the internal structure of dunes carried out with ground penetrating radar and supported by data from topographic dgps these analyses are of great importance to ascertain the state of the internal structure of dunes as an important element in their stability and therefore in their evolution the internal structure shows accretion and progradation sequences of dunes over beach deposits which depend on dune morphology height crest orientation and location as well as the processes acting on them

the chemical composition of martian soil and rocks returned by the mobile alpha proton x ray spectrometer preliminary results from the x ray mode the alpha proton x ray spectrometer apxs on board the rover of the mars pathfinder mission measured the chemical composition of six soils and five rocks at the ares vallis landing site the soil analyses show similarity to those determined by the viking missions the analyzed rocks were partially covered by dust but otherwise compositionally similar to each other they are unexpectedly high in silica and potassium but low in magnesium compared to martian soils and martian meteorites the analyzed rocks are similar in composition to terrestrial andesites and close to the mean composition of earth s crust addition of a mafic component and reaction products of volcanic gases to the local rock material is necessary to explain the soil composition

sea level controls on carbonate beaches and coastal dunes eolianite lessons from pleistocene bermuda 2015 geological society of america coastal dune accumulations at locations around the world have formed during sea level highstands rising sea levels falling sea levels and fluctuating sea levels initially episodes of maximum pleistocene dune activity in bermuda which is the type location for eolianite were correlated with glacio eustatic regressions this model had been abandoned by the 1970s in favor of a rising sea level model for bermuda s north shore and autogenic sediment supply model for the south shore we report the results of a detailed investigation of the intercalated mid late pleistocene beach and coastal dune deposits on the islands of bermuda and we test the existing models for these deposits we contend that the north shore model is invalidated by past misidentification of eoliandeposits as transgressive beach deposits on the south shore facies analysis of the marine isotope stage 7 mis 7 belmont formation reveals that coastal deposition was divided into two phases s1 which includes foreshore and shoreface progradation is predominantly marine and coincided with rising relative sea level s2 which commenced with protosol development on top of the marine section prior to burial by advancing dunes is nonmarine we conclude that the two successions s1 and s2 resulted from forcing by glacio hydro isostatic relative sea level change spanning a highstand rising and then falling rather than from transgressive or autogenic processes the finding that in bermuda the construction of protective coastal dunes depends on a falling relative sea level has potential implications for many vulnerable shorelines that face rising relative sea levels associated with climate change

the impact of north atlantic storminess on western european coasts a review abstract instrumental and documentary records of storminess along the atlantic coast of western europe show that storm activity exhibits strong spatial and temporal variability at annual and decadal scales there is evidence of periods of increased storminess during the little ice age lia ad 1570 1990 and archival records show that these periods are also associated with sand movement in coastal areas independent evidence of sand movement during the lia is derived from dating the coastal sand deposits using luminescence or radiocarbon methods the holocene record of sand drift in western europe includes episodes corresponding to periods of northern hemisphere cooling particularly at 8 2 ka and provides the additional evidence that these periods like the lia were also stormy

refined data of alpha proton x ray spectrometer analyses of soils and rocks at the mars pathfinder site implications for surface chemistry 1 an extensive recalibration of the alpha proton x ray spectrometer apxs was performed to improve the data evaluation of the mars pathfinder mpf rock and soil in situ measurements many samples and geostandards were measured with an mpf identical spare apxs under simulated martian atmospheric pressure and low night temperature conditions precise calibration curves for major and minor elements were obtained using an improved spectral evaluation method for the original mpf spectra refined and new elemental compositions of the mpf rocks and soils were derived however all initial conclusions about soils and rocks remained valid the mpf soil composition revealed the mafic nature of the surface as inferred from the results of viking 1 and 2 data however the mpf rocks reflect a felsic composition for all samples linear correlations of sulphur with all other elements were noticed reflecting the fact that the rocks were covered with varying degrees of soil which compared to the rocks is rich in sulphur extrapolating to low sulphur abundance 0 3 the composition of a soil free rock was calculated the mpf rock composition is high in si and k and low in mg and fe compared to the soil using elemental data from mpf and martian meteorites a global estimation of the martian crust composition was derived the crust is of basaltic nature with a high abundance of incompatible elements k rb nd u th and volatile elements s cl while carbonates are lower or absent

accelerated transgressive processes in a mediterranean coastal barrier subsidence anthropic action and geomorphological changes since the little ice age abstract subsidence changes in sediment supply and environments sea storms current sedimentary deficit and recent anthropic action are factors determining coastal geomorphological processes and evolution of a transgressive mediterranean coastal barrier at a longer timescale the barrier landward migration is partially due to local subsidence of tectonic origin peatmarsh remains under seawater at around 100 m from the present day coastline 4821 4566 and 4874 4820 cal bp show evidence of the more advanced position towards the sea of the late holocene coastal barrier which has not been preserved furthermore behind the present gravel barrier wide sandy washover fans dating about 665 cal bp and 503 cal bp were deposited in the early little ice age lia and during the sporer minimum in periods when sea storms were highly frequent in the western mediterranean the source of the washover fine sands was an ancient deltaic lobe of the sant miquel river southern palaeochannel the avulsion towards the current northern mouth ca 1790 produced important sedimentary coastal changes from fine to gravelly sands more recently gravelly washover fans indicating rollover processes were found in the 1945 barrier nevertheless progradational sets of gravelly beach ridges were identified in the central sector between 1977 and 1997 since 2003 overtop and overwash processes during storms have formed a steep beach ridge nearly 3 m high finally recent direct anthropic action has favoured rapid landward migration of the barrier with processes of fast rollover cannibalization and dissolution phases

determination of the chemical composition of martian soil and rocks the alpha proton x ray spectrometer the alpha proton x ray spectrometer apxs for the mars pathfinder mission is designed to provide a complete and detailed analysis of chemical elements in martian soil and rocks near the landing site the apxs instrument is carried on the pathfinder microrover which will provide transportation to places of interest on the martian surface it consists of a complex sensor head mounted on a simple but sophisticated apxs deployment mechanism adm outside the warm electronics box web of the microrover and the instrument electronics mounted inside the web the adm permits the instrument sensor head to be placed against soil and rock samples in arbitrary positions ranging from horizontal to vertical in order to perform in situ analysis the possibility to transport the apxs to an arbitrary location preselected on earth and to perform in situ analysis there constitutes one of the most exciting aspects of the pathfinder mission the principle of the apxs technique is based on three interactions of alpha particles from a radioisotope source with matter simple rutherford backscattering production of protons from p reactions on light elements and generation of characteristic x rays upon recombination of atomic shell vacancies created by a bombardment measurement of the intensities and energy distributions of these three components yields information on the abundance of chemical elements in the sample in terms of sensitivity and selectivity data are partly redundant and partly complementary alpha backscattering is superior for light elements c o while proton emission is mainly sensitive to na mg al si s and x ray emission is more sensitive to heavier elements na to fe and beyond a combination of all three measurements enables determination of all elements with the exception of h and he present at concentration levels above typically a fraction of 1

the late holocene coastal dunefield at vejers denmark characteristics sand budget and depositional dynamics abstract the coastal dunefield at vejers west coast of jutland which is now stabilized by vegetation covers an area of approximately 120 km 2 and occurs in a very high energy wind regime along the coastline a narrow belt of 5 15 m high dune ridges occur the dune ridges are gradually replaced inland by 10 20 m high parabolic or irregular dune forms in the central part of the dunefield a large aeolian sand plain ca 50 km 2 occurs at the windward side of a large and up to 20 m high parabolic dune the 3d structure of the dunefield deposits have been studied by geomorphological analysis sedimentological facies analysis of borings trenches and natural exposures and most importantly by georadar mapping the aeolian deposits which overlie a middle to late holocene barrier spit depositional system can be divided into a lower unit that drapes the underlying barrier system topography and an upper unit that includes the present dunes the boundary between the two aeolian units is a well developed phragmites peat the lower aeolian unit is composed of two aeolian subunits separated by an organic rich horizon also the upper unit is composite and composed of a basal aeolian sand cover and overlying dune or sand plain deposits the dune deposits locally are composed of up to four depositional subunits separated by immature soils the base of the lower aeolian unit formed around 300 a d whereas the phragmites peat at the base of the upper aeolian unit has been dated to ca 1000 a d from historical sources we know that the present dunefield primarily formed between 1550 and 1850 a d the sand content in the upper unit is estimated to 550 10 6 m 3 which yields sand transport rates between 25 m 3 m width 1 yr 1 accumulation in 1000 years and 83 m 3 m width 1 yr 1 accumulation in 300 years the sand in the dunefield originated from beach deposits a large but pulsating supply of sand was supplied to the beaches by southwards running coastal currents the composition of the vejers dunefield deposits indicate that periods of dunefield growth alternated with periods of dunefield stabilization during the last ca 1700 years the final and most important phase of dunefield growth took place during the little ice age this period was characterized by an overall cold and stormy climate and a relative low sea level and resulted in an increased availability of sand in the shorezone and a high influx of sand into the dunefield short periods of decreased storminess are recorded by the immature soils dunefield growth prior to 1000 a d was also linked to cold and stormy climatic intervals

the shikotan earthquake of october 4 1994 lithospheric earthquake a large m w 8 2 earthquake occurred off shikotan is one of the kurile is on october 4 1994 we inverted 32 body wave records to determine the rupture pattern using an iterative deconvolution method the mechanisms of the subevents were allowed to vary during rupture the source parameters obtained are the location of the initial break 43 48 n 147 40 e the centroid depth 56 km strike dip rake 49 75 125 for the total source the seismic moment m o 2 6 10 21 nm m w 8 2 source time duration t 42 s the average rupture velocity 2 5 km s we also determined the mechanism using long period love and rayleigh waves from 14 stations the solution for a finite source distributed over a depth range from 0 to 90 km is strike dip rake 54 76 129 with mo 2 3 10 21 nm in good agreement with that from body waves referring to the extent of the aftershock area and the subevent distribution we estimated the fault area s 120 60 km the average slip d 5 6m and the stress drop 11 mpa we computed synthetic waveforms as well as static displacements using either the steep or the low angle plane as the fault plane and found that the steep dip fault model fits the data better our result the mechanism large centroid depth high stress drop strongly suggests that the 1994 shikotan earthquake is a lithospheric earthquake an intra plate event that ruptures through a substantial part of the subducting oceanic lithosphere this type of lithospheric earthquake is relatively common

evolution of a large baltic beach ridge plain neudarss ne germany a continuous record of sea level and wind field variation since the homeric minimum

evidence of 210po on martian dust at meridiani planum 1 since the surveyor and apollo missions and up to the recent lunar prospector mission 222rn and 210po have been key isotopes for understanding gas release events and their spatial and temporal variations on the moon comparatively these isotopes have drawn much less attention on mars if any despite the wealth of information it could bring on the uppermost meters of the regolith the exchange of volatiles at the surface and the atmospheric aerosol cycle here we present a statistical analysis of the high energy end of alpha spectra obtained by the alpha particle x ray spectrometer onboard mars exploration rover opportunity and report evidence of 210po a decay product of 222rn attached to atmospheric dust the 210po surface activity on rocks and soils at the landing site is lower than 3 1 10 4 bq cm 2 but analysis of spectra obtained on the dust capture magnet reveals a 210po activity of 4 6 2 4 10 3 bq cm 2 2 this difference is due to the very low dust cover index at the landing site owing to frequent dust devils regional and global dust storms that mobilize substantial amounts of dust and homogenize the dust surface layer we infer that the global average 222rn exhalation rate is significantly greater on mars than on the moon this comparison supports the hypothesis that on mars radon emanation could be comparatively enhanced by the presence of water in the surficial soil analysis of atmospheric spectra yields a radon activity upper limit of 16 5 bq m 3 during nighttime at the landing site

alpha particle x ray spectrometer apxs results from gusev crater and calibration report 1 the chemical composition of rocks and soils on mars analyzed during the mars exploration rover spirit mission was determined by x ray analyses with the alpha particle x ray spectrometer apxs details of the data analysis method and the instrument calibration are presented measurements performed on mars to address geometry effects and background contributions are shown cross calibration measurements among several instrument sensors and sources are discussed an unintentional swap of the two flight instruments is evaluated new concentration data acquired during the first 470 sols of rover spirit in gusev crater are presented there are two geological regions the gusev plains and the columbia hills the plains contain soils that are very similar to previous landing sites on mars a meteoritic component in the soil is identified rocks in the plains revealed thin weathering rinds the underlying abraded rock was classified as primitive basalt one of these rocks contained significant br that is probably associated with vein filling material of different composition one of the trenches showed large subsurface enrichments of mg s and br disturbed soils and rocks in the columbia hills revealed different elemental compositions these rocks are significantly weathered and enriched in mobile elements such as p s cl or br even abraded rock surfaces have high br concentrations thus in contrast to the rocks and soils in the gusev plains the columbia hills material shows more significant evidence of ancient aqueous alteration

evolution of a beach dune system following a catastrophic storm overwash event greenwich dunes prince edward island 1936 2005 greenwich dunes prince edward island national park is a sandy mainland and barrier spit beach dune complex stretching for about 10 km along the northeast shore of prince edward island canada in october 1923 surge associated with an intense storm produced catastrophic overwash along the whole length of the study area subsequent evolution of the system was quantified from historic aerial photographs taken in 1936 1953 1971 1997 and 2005 orthophoto mosaics were generated for each photo set using pci geomatica orthoengine a digital photogrammetric software linear changes in shoreline position and areal changes in geomorphic units were evaluated for each photo set in addition digital elevation models dems were extracted from the 1953 1971 and 1997 aerial photos enabling analysis of topographic and volumetric changes the 1936 photos show complete destruction of all foredunes with overwash and transgressive dunes extending 300 to 600 m inland a descriptive model of the stages of evolution

the mars pathfinder mission mars pathfinder one of the first discovery class missions quick low cost projects with focused science objectives will land a single spacecraft with a microrover and several instruments on the surface of mars in 1997 pathfinder will be the first mission to use a rover carrying a chemical analysis instrument to characterize the rocks and soils in a landing area over hundreds of square meters on mars which will provide a calibration point or ground truth for orbital remote sensing observations in addition to the rover which also performs a number of technology experiments pathfinder carries three science instruments a stereoscopic imager with spectral filters on an extendable mast an alpha proton x ray spectrometer and an atmospheric structure instrument meteorology package the instruments the rover technology experiments and the telemetry system will allow investigations of the surface morphology and geology at submeter to a hundred meters scale the petrology and geochemistry of rocks and soils the magnetic properties of dust soil mechanics and properties a variety of atmospheric investigations and the rotational and orbital dynamics of mars landing downstream from the mouth of a giant catastrophic outflow channel ares vallis at 19 5 n 32 8 w offers the potential of identifying and analyzing a wide variety of crustal materials from the ancient heavily cratered terrain intermediate aged ridged plains and reworked channel deposits thus allowing first order scientific investigations of the early differentiation and evolution of the crust the development of weathering products and the early environments and conditions on mars

the dynamic rupture process of the 1993 kushiro oki earthquake we have constructed a dynamic rapture model of the 1993 kushiro oki earthquake mw 7 6 that is consistent with the observed seismograms this earthquake occurred beneath the city of kushiro japan at a depth of about 100 km and the aftershocks are limited to a horizontal plane between a double seismic zone in the subducting slab excellent near field strong motion records are available in our analysis a kinematic inversion is followed by a dynamic crack calculation and this pair of operations is repeated until convergence to the data is obtained two different conditions concerning the dynamic stress drop were considered in the dynamic calculation and a dynamic model was constructed for each condition the difference in these conditions has little effect on the results the final dynamic model shows that this earthquake occurred with a localized high stress drop of about 40 mpa in the subducting slab which indicates that the region between the double seismic zone is strong enough to sustain such a high stress one of the two high strength regions in the final model lies near the upper plane of the double seismic zone and represents a barrier due to a substantial change of stress state in the slab in the region where the initial breaks occurred 5 s before the main rupture both the strength and the stress drop are smaller than in the adjacent region this implies that before the main rupture the accumulated stress had already been released in the area of the initial breaks the aftershocks tend to occur near the high strength area in some of them the p wave first motions are opposite to those of the main shock

development of the mars microbeam raman spectrometer mmrs 1 raman spectroscopy is a powerful tool for mineral characterization and for detection of water and organic and inorganic forms of carbon the mars microbeam raman spectrometer mmrs is designed for close up analysis of rocks and soils in planetary surface exploration the mmrs consists of a probe in a flight unit to be deployed by a robotic arm and a spectrograph laser source and electronics in a flight unit to reside on a rover or lander the raman probe has a scanning optical bench that enables a 1 cm linear traverse across a target rock or soil both on target materials as encountered and on fresh surfaces of rocks exposed by abrasion or coring from these spectra one can identify major minor and trace minerals obtain their approximate relative proportions and determine chemical features e g mg fe ratio and rock textural features e g mineral clusters amygdular fill and veins one can also detect and identify organic species graphitic carbon and water bearing phases extensive performance tests have been done on a brassboard model of the mmrs using a variety of geological materials minerals rocks martian meteorites etc these tests show that a raman spectrometer can be built that is suitably miniaturized sufficiently robust and low enough in power usage to serve as an on surface planetary instrument yet the spectrometer can retain high detection sensitivity and yield near laboratory quality spectra over a broad wavelength range these features are essential to provide definitive mineralogy in a planetary exploration

the imager for mars pathfinder experiment the imager for mars pathfinder imp a stereoscopic multispectral camera is described in terms of its capabilities for studying the martian environment the camera s two eyes separated by 15 0 cm provide the camera with range finding ability each eye illuminates half of a single ccd detector with a field of view of 14 4 14 0 and has 12 selectable filters the 18 optics have a large depth of field and no focussing mechanism is required a mechanical shutter is avoided by using the frame transfer capability of the 512 512 ccd the resolving power of the camera 0 98 mrad pixel is approximately the same as the viking lander cameras however the signal to noise ratio for imp greatly exceeds viking approaching 350 this feature along with the stable calibration of the filters between 440 and 1000 nm distinguishes imp from viking specially designed targets are positioned on the lander they provide information on the magnetic properties of wind blown dust measure the wind vectors and provide radiometric standard reflectors for calibration also eight low transmission filters are included for imaging the sun directly at multiple wavelengths giving imp the ability to measure dust opacity and potentially the water vapor content several experiments beyond the requisite color panorama are described in detail contour mapping of the local terrain multispectral imaging of the surrounding rock and soil to study local mineralogy viewing of three wind socks measuring atmospheric opacity and water vapor content and estimating the magnetic properties of wind blown dust this paper is intended to serve as a guide to understanding the scientific integrity of the imp data that will be returned from mars starting on july 4 1997

general geology and geomorphology of the mars pathfinder landing site the mars pathfinder mpf spacecraft landed on relatively young late hesperian early amazonian 3 1 0 7 ga plains in chryse planitia near the mouth of ares vallis images returned from the spacecraft reveal a complex landscape of ridges and troughs large hills and crater rims rocks and boulders of various sizes and shapes and surficial deposits indicating a complex multistage geologic history of the landing site after the deposition of one or more bedrock units depositional and erosional fluvial processes shaped much of the present landscape multiple erosional events are inferred on the basis of observations of numerous channels different orientations of many streamlined tails from their associated knobs and hills and superposition of lineations and streamlines medium and small scale features interpreted to be related to late stage drainage of floodwaters are recognized in several areas at the landing site streamlined knobs and hills seen in viking orbiter images support this inference as they seem to be complex forms partly erosional and partly depositional and may also indicate a series of scouring and depositional events that in some cases further eroded or partially buried these landforms although features such as these are cited as evidence for catastrophic flooding at ares vallis some of these features may also be ascribed to alternative primary or secondary depositional processes such as glacial or mass wasting processes close inspection of the landing site reveals rocks that are interpreted to be volcanic in origin and others that may be conglomeratic if such sedimentary rocks are confirmed fluvial processes have had a greater significance on mars than previously thought for the last several hundred million to few billion years eolian processes have been dominant dunes and dune like features ventifacts and deflation and exhumation features around several rocks probably are the most recent landforms the relatively pristine nature of the overall landscape at the mpf site suggests weathering and erosion processes on mars are exceptionally slow

overview of the mars pathfinder mission launch through landing surface operations data sets and science results mars pathfinder successfully landed at ares vallis on july 4 1997 deployed and navigated a small rover about 100 m clockwise around the lander and collected data from three science instruments and ten technology experiments the mission operated for three months and returned 2 3 gbits of data including over 16 500 lander and 550 rover images 16 chemical analyses of rocks and soil and 8 5 million individual temperature pressure and wind measurements path finder is the best known location on mars having been clearly identified with respect to other features on the surface by correlating five prominent horizon features and two small craters in lander images with those in high resolution orbiter images and in inertial space from two way ranging and doppler tracking tracking of the lander has fixed the spin pole of mars determined the precession rate since viking 20 years ago and indicates a polar moment of inertia which constrains a central metallic core to be between 1300 and 2000 km in radius dark rocks appear to be high in silica and geochemically similar to anorogenic andesites lighter rocks are richer in sulfur and lower in silica consistent with being coated with various amounts of dust rover and lander images show rocks with a variety of morphologies fabrics and textures suggesting a variety of rock types are present rounded pebbles and cobbles on the surface as well as rounded bumps and pits on some rocks indicate these rocks may be conglomerates although other explanations are also possible which almost definitely require liquid water to form and a warmer and wetter past air borne dust is composed of composite silicate particles with a small fraction of a highly magnetic mineral interpreted to be most likely maghemite explanations suggest iron was dissolved from crustal materials during an active hydrologic cycle with maghemite freeze dried onto silicate dust grains remote sensing data at a scale of a kilometer or greater and an earth analog correctly predicted a rocky plain safe for landing and roving with a variety of rocks deposited by catstrophic floods which are relatively dust free the surface appears to have changed little since it formed billions of years ago with the exception that eolian activity may have deflated the surface by 3 7 cm sculpted wind tails collected sand into dunes and eroded ventifacts fluted and grooved rocks pathfinder found a dusty lower atmosphere early morning water ice clouds and morning near surface air temperatures that changed abruptly with time and height small scale vortices interpreted to be dust devils were observed repeatedly in the afternoon by the meteorology instruments and have been imaged

development and setting of the alcudia bay beach dune system mallorca spain abstract the beach dune system of alcudia bay is located in the north of the island of mallorca the system includes both simple and compound parabolic dunes formed by n to nne winds and is made up of two dune areas with different dynamics 1 the northern area where despite the fact that the source of beach sediment is from the south dunes are formed by northerly winds and develop a narrow and linear barrier which separates a marsh from the bay and 2 the southern area where complex parabolic dunes formed by north northeasterly winds prograde south southwest landward extending several kilometers inland the broad pattern of the dunefield size is limited to the southeast by a mountain range and to the west by the effects of a topographic corridor oriented north south which channels the prevailing northerly wind causing a southward dune progression and limiting the westward extension of the dunefield

a detailed subduction structure in the kuril trench deduced from ocean bottom seismographic refraction studies abstract in 1983 we conducted an ocean bottom seismograph obs experiment in the southernmost part of the kuril trench beneath which the pacific plate is subducting under hokkaido island japan the aim of this experiment was to determine crust and upper mantle structure from the oceanic basin to the continental slope by dense seismic refraction profiling using explosives and airguns the total length of the profiles was 560 km along which ten obs s were deployed the observed data were of good quality which enabled us to obtain a detailed velocity structure of the active margin down to 20 30 km we constructed a velocity structure model by ray tracing and amplitude modeling in the oceanic basin the crust has a typical oceanic structure characterized by three layers with p wave velocities of 1 8 3 8 6 5 and 6 5 7 0 km s the velocity gradient in layer 3 increases downward from 0 075 to 0 10 s 1 the moho discontinuity was well constrained by clearly observed p n and p m p phases the total thickness of the oceanic crust was determined to be 8 km and almost constant in the oceanic basin the p wave velocity is 7 9 km s beneath the moho discontinuity which increases downward with a rather small velocity gradient 0 015 0 03 s 1 beneath the continental slope we found relatively low velocity 2 5 to 5 5 5 8 km s material the oceanic moho discontinuity associated with the subducting plate was traced down to a depth of 25 km our seismic data strongly suggest that oceanic layer 2 is smoothly subducting and does not break up to form a wedge structure this result is in remarkable contrast with the velocity structure in the active margin of the ryukyu trench area about 1000 km south of the present experimental area where we found a 12 km thick prominent low velocity wedge is situated 50 150 km landward from the trench axis on the seaward side of the wedge the surface of the igneous basement undulates severely the wedge was probably formed by materials of oceanic origin such a difference in velocity structure suggests that the subduction mechanism in the trench area differs from region to region in the northwestern pacific

the pathfinder microrover an exciting scientific component of the pathfinder mission is the rover which will act as a mini field geologist by providing us with access to samples for chemical analyses and close up images of the martian surface performing active experiments to modify the surface and study the results and exploring the landing site area

sediment supply from shoreface to dunes linking sediment transport measurements and long term morphological evolution a significant problem in current coastal research is the understanding of linkages between morphological phenomena occurring on different temporal and spatial scales morphodynamic processes in the nearshore typically exhibit nonlinear behaviour and consequently phenomena which occur on short temporal event scales as e g observed during field experiments have generally been difficult to upscale to provide an understanding of the long term behaviour of the coast on the time scale of seasons or decades this paper documents a persistent onshore migration of nearshore bar features over a period of 3 decades using a set of cross shore profile surveys from a barrier on the danish north sea coast the observed behaviour is consistent with experimental data obtained during weeklong field campaigns when sediment transport and bar migration were found to be landward directed during high energy dissipative conditions hydrodynamic and sediment transport processes leading to onshore bar migration and eventually welding of the bars are documented to provide an explanation for the observed long term evolutionary trends in addition bar welding and the resulting intertidal bar formation represent an onshore sediment storage which is subsequently available for aeolian transport observations on aeolian sediment transport indicate that transport rates and sediment supply to the foredunes critically depend on the presence of dry sand sources as represented by well drained intertidal bars measurements of long term accretion rates in foredunes indicate that volumes deposited on the crest and lee slope of the dunes are in reasonable correspondence with volumes supplied to the subaerial beach through the process of bar welding hence the data suggest that a persistent onshore directed sediment supply occurs from the shoreface across the surf and intertidal zones and into the dunes of the investigated barrier

tracing sea level changes during the mid holocene in the southern mediterranean coast an example from the gulf of gabes abstract mid holocene sea level emergence was recorded along a mid latitude coastal site in the gulf of gabes tunisia in beach rock deposits however the post emergence sea level curve and associated hydro sedimentary processes have rarely been documented this study presents new records of sea level changes along the tunisian coast since the mid holocene each phase of the sea level curve was evidenced and supported by lithostratigraphic morphological and archaeologic markers post emergence sea level fall due to postglacial isostatic rebound was recognized in regressive sequences which vary depending on available accommodation space from a small pocket beach to a well developed dune system sea level stabilization following isostatic rebound has promoted the end phase deposits of the regressive sequences however this stability was interrupted during the late holocene by a high energy storm event that accumulated a transgressive boulder unit at 2 m above present shape and disposition of the boulder ridge behind a prograding modern shoreline suggests that sea level has not changed during the late holocene the existence of a roman fish pond on the upper foreshore confirms stability of sea level during the last two millennia the combination of lithostratigraphic morphological and archaeologic markers represents a tool for improving the accuracy of dating of erosional and depositional periods in mid coastal sections

alteration of immature sedimentary rocks on earth and mars recording aqueous and surface atmosphere processes the rock alteration and rind formation in analog environments like antarctica may provide clues to rock alteration and therefore paleoclimates on mars clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of mars moreover how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows here we characterize alteration in the chemically immature carapace sandstone from antarctica a terrestrial analog for martian sedimentary rocks we employ a variety of measurements similar to those used on previous and current mars missions laboratory techniques included bulk chemistry powder x ray diffraction xrd hyperspectral imaging and x ray absorption spectroscopy through these methods we find that primary basaltic material in the carapace sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water rock interaction a thick orange rind is forming in current antarctic conditions superimposing this previous aqueous alteration signature the rind exhibits a higher reflectance at visible near infrared wavelengths than the rock interior with an enhanced ferric absorption edge likely due to an increase in fe3 of existing phases or the formation of minor iron oxy hydroxides more this alteration sequence in the carapace sandstone results from decreased water rock interaction over time and weathering in a cold dry environment mimicking a similar transition early in martian history this transition may be recorded in sedimentary rocks on mars through a similar superimposition mechanism capturing past climate changes at the hand sample scale these results also suggest that basalt derived sediments could have sourced significant volumes of hydrated minerals on early mars due to their greater permeability compared with intact igneous rocks less

characteristics of the pathfinder apxs sites implications for the composition of martian rocks and soils an integrated study of spectral elemental abundance and image data from the pathfinder alpha proton x ray spectrometer apxs measurement sites has led to a better understanding of the nature of martian surface materials this rigorous analysis provides a new level of detail that forms the basis for the results reported here and that can be used by future scientists trying to understand rocks and soils on mars each apxs site has been precisely located by analyzing stereo imager for mars pathfinder imp and rover camera images to determine the position of the apxs during deployment rover and imp images are used to assess local geology namely the presence of pebbles clods and aeolian features in soils and surface textures and dust concentrations on rocks imp spectra using the latest calibrations for radiance and reflectance are analyzed at a number of different illumination geometries for each apxs site the three dimensional orientation of the sites has been determined and then used to compute the true sunlight incidence and viewing emission angles where suitable photometric coverage is available reflectances are fit to the hapke irvine function this is then used to adjust spectral reflectances to a normalized illumination geometry common to all rocks and soils comparing all the data sets shows a positive correlation among red blue reflectance ratio so3 content and dust abundance on rocks indicating that rocks are coated with varying amounts of sulfur rich red dust other elements such as silicon and iron are poor tracers for dust because their abundances within soil are similar to those within rock rock apxs targets that are bluer poorer in sulfur and have minimal dust coverage face toward the northeast the direction in which winds may be capable of efficiently removing loose material under current martian conditions the imp spectral properties of the soils show poor correlations with apxs elemental abundances on the basis of currently released apxs data bulk soils at the pathfinder landing site are richer in silica and sulfur than the viking landing sites suggesting a different composition the apxs soils with the most apparent pebbles are the poorest in sio2 indicating that either the pebbles are more mafic than the apxs rocks or the pebble free soil component is inherently enriched in sio2 compared to viking soils the mixture of materials at the apxs sites is a reflection of the overall complexity of martian surface materials a detailed understanding of which should drive the choice of future instruments and missions

rupture process of the 2008 northern iwate intraslab earthquake derived from strong motion records the rupture process of the 2008 northern iwate japan earthquake m 6 8 has been derived from strong motion records obtained at 22 regional stations by the multi time window linear waveform inversion method this event occurred in the lower plane of the double seismic zone in the subducting pacific slab at a depth of 115 km a preliminary inversion analysis revealed that a single planar fault plane model was insufficient to satisfactorily explain waveforms at stations in a specific azimuth a two segment fault plane model was then assumed in which the fault model consisted of the northern and southern segments with a 44 difference in strike direction which respectively followed the source mechanisms determined by moment tensor inversion and p wave polarity analysis the source model derived from the two segment fault plane model greatly improved the waveform fitting at stations for which there was a large discrepancy in the preliminary analysis with the single planar fault plane model the largest asperity was located on the northern segment which generated the main phase observed at most stations the amount of slip on the southern segment was smaller but contributed significantly to the first of the two pulses observed at the stations to the south of the source area the stress drop of the largest asperity for this intraslab earthquake was large in comparison with that predicted from empirical relations obtained for crustal earthquakes which may be one of the causes of the relatively large accelerations recorded during this earthquake

correlating multispectral imaging and compositional data from the mars exploration rovers and implications for mars science laboratory abstract in an effort to infer compositional information about distant targets based on multispectral imaging data we investigated methods of relating mars exploration rover mer pancam multispectral remote sensing observations to in situ alpha particle x ray spectrometer apxs derived elemental abundances and mossbauer mb derived abundances of fe bearing phases at the mer field sites in gusev crater and meridiani planum the majority of the partial correlation coefficients between these data sets were not statistically significant restricting the targets to those that were abraded by the rock abrasion tool rat led to improved pearson s correlations most notably between the red blue ratio 673 nm 434 nm and fe3 bearing phases but partial correlations were not statistically significant partial least squares pls calculations relating pancam 11 color visible to near ir vnir 400 1000 nm spectra to apxs and mossbauer element or mineral abundances showed generally poor performance although the presence of compositional outliers led to improved pls results for data from meridiani when the meridiani pls model for pyroxene was tested by predicting the pyroxene content of gusev targets the results were poor indicating that the pls models for meridiani are not applicable to data from other sites soft independent modeling of class analogy simca classification of gusev crater data showed mixed results of the 24 gusev test regions of interest rois with known classes 11 had 30 of the pixels in the roi classified correctly while others were mis classified or unclassified k means clustering of apxs and mossbauer data was used to assign meridiani targets to compositional classes the clustering derived classes corresponded to meaningful geologic and or color unit differences and simca classification using these classes was somewhat successful with 30 of pixels correctly classified in 9 of the 11 rois with known classes this work shows that the relationship between swir multispectral imaging data and apxs and mossbauer derived composition mineralogy is often weak a perhaps not entirely unexpected result given the different surface sampling depths of swir imaging uppermost few microns vs apxs tens of m and mb measurements hundreds of m results from the upcoming mars science laboratory msl rover s chemcam laser induced breakdown spectroscopy libs instrument may show a closer relationship to mastcam swir multispectral observations however because the initial laser shots onto a target will analyze only the upper few micrometers of the surface the clustering and classification methods used in this study can be applied to any data set to formalize the definition of classes and identify targets that do not fit in previously defined classes

source models of two large intraslab earthquakes from broadband strong ground motions we construct source models of two large intraslab earthquakes the 1993 kushiro oki and 1994 hokkaido toho oki earthquakes along the southern kurile hokkaido arc based on strong motion records the source models well explain observed broadband strong ground motions we assume a distribution of rectangular shaped asperities on a fault plane and apply the empirical green9s function method to the synthesis of strong ground motions from the asperities the asperity parameters area and stress drop are estimated by matching the synthetic waveforms displacement velocity and acceleration time histories and spectra to the observed ones our source models have the following characteristics compared with those of inland and plate boundary earthquakes having a comparable seismic moment 1 the total asperity area is much smaller and 2 the stress drop is extremely high about 200 400 mpa these indicate that the large intraslab earthquakes radiate seismic energies from a small area in a short time this rupture process results in extremely strong radiation of short period seismic waves finally we confirm a correlation between outer entire fault size seismic moment and short period level of the acceleration source spectrum and inner fault parameters areas and stress drops of asperities for the two intraslab earthquakes

a general framework for modeling sediment supply to coastal dunes including wind angle beach geometry and fetch effects a series of spatially explicit equations are derived that form the foundation of a modeling framework that provides insight into how the interaction of the fetch effect and angle of wind approach leads to tradeoffs that govern the magnitude of aeolian sediment transport across beaches of different geometry the spatial distribution of sediment transport rate per unit width at any point on the beach is shown to vary predictably as a function of wind angle critical fetch and beach geometry and this has evident implications for the total volume and distribution of sediment transport into the dunes behind the beach as well as the proportion of sediment lost from the beach dune system at the downwind margin as the wind field shifts from onshore shore perpendicular to oblique shore parallel approach angle total sediment transport rate across a dune line segment will reflect a tradeoff between transport reduction because of the cosine effect and transport enhancement because of potentially longer fetch distances traversed by the wind prior to encountering the dune line this tradeoff is most evident on long narrow beaches when beach width is less than the critical fetch for such beaches and with onshore winds the total sediment transport rate across the dune line will be less than that predicted for a wide beach because of the constraint imposed by the fetch effect however as the angle of wind approach becomes oblique the available fetch becomes progressively longer transport limitations imposed by the fetch effect are negated and transport enhancement across the dune line is to be expected with very large angles of wind approach the cosine effect dominates the interaction and transport reductions across the dune line occur until the wind is shore parallel and sediment supply to the dunes ceases altogether this sequence of adjustments and tradeoffs were only partially understood prior to this study and yet they form the foundation of coastal dune modeling the framework proposed in this paper serves to place future studies of process form interaction in beach dune systems on a robust theoretical foundation it also facilitates the testing of various alternative hypotheses regarding the uneven spatial and temporal distribution of dune height and growth rate in coastal environments

aeolian sand movement and relative sea level rise in ho bugt western denmark during the little ice age this study documents an extensive aeolian sand sheet buried in the salt marshes of the ho bugt embayment in western denmark the extent of the sand sheet was mapped from c 60 cores and sections which were also used to reconstruct late holocene changes in relative sea level based on diatom analyses chronology was provided by optically stimulated luminescence osl and radiocarbon dating our study shows that since 2000 cal yr bp relative sea level in ho bugt has risen by approximately 1 5 m the overall rise was punctuated by two periods with higher than average rates of sea level rise the first between 2000 and 1400 cal yr bp and the second commencing c 500 cal yr bp around 700 cal yr bp the evolution of the skallingen spit may have been responsible for a reduction in the local tidal range and the formation of an extensive black layer in the western part of the embayment osl analyses date the sand sheet to between ad 1460 40 and ad 1550 30 490 40 and 400 30 cal yr bp consistent wi

environmental controls on coastal dune formation skallingen spit denmark abstract many coastal dune systems in western europe were emplaced during the little ice age lia the formation of such dune fields has generally been ascribed to a combination of low sea level and strong winds during that time period providing a supply of sand from the exposed shoreface and sufficient wind energy to transport this sand landward however little information exists on the processes that controlled sediment supply to the beach and why this onshore supply was initiated at all in this contribution we consider the origin and development of older dune fields on a barrier spit complex skallingen located in the northern part of the danish wadden sea maps and new data on dune litho and chrono stratigraphy the latter based on osl dating allow a precise estimate of the initiation and termination of dune emplacement dune formation at skallingen started at a relatively late stage of the lia and it can be temporally correlated with a phase of relative sea level rise in north western europe and with a high frequency of storm surges along the danish west coast these are the conditions during which nearshore bars currently migrate onshore across the shoreface off skallingen the bars eventually merge with the beach and constitute a source of sand for modern foredune accretion it is probable that the onshore bar migration occurred under similar conditions in the past and the migration was triggered or enhanced by the sea level recovery from the mid lia low stand and the associated frequent storm surge activity consequently at skallingen onshore sand supply was caused by marine rather than aeolian agents this supply provided the basis for subsequent dune formation indications are however that the sediment supply to the beach dunes was a factor of 2 3 larger in the past dune aggradation eventually ceased around 1900ad because of dyke construction hence the association between dune formation and sea level surge variation at skallingen is somewhat contrary to other statements of coastal dune development during the lia in north western europe

chemical composition of martian fines of the 21 samples acquired for the viking x ray fluorescence spectrometer 17 were analyzed to high precision compared to typical terrestrial continental soils and lunar mare fines the martian fines are lower in al higher in fe and much higher in s and cl concentrations protected fines at the two lander sites are almost indistinguishable but concentration of the element s is somewhat higher at utopia duricrust fragments successfully acquired only at the chryse site invariably contained about 50 higher s than fines no elements correlate positively with s except cl and possibly mg a sympathetic variation is found among the triad si al ca positive correlation occurs between ti and fe sample variabilities are as great within a few meters as between lander locations 4500 km apart implying the existence of a universal martian regolith component of constant average composition the nature of the source materials for the regolith fines must be mafic to ultramafic

chemical compositions at mars landing sites subject to mars odyssey gamma ray spectrometer constraints 1 the mars odyssey gamma ray spectrometer grs is the first instrument suite to return elemental abundances throughout the midlatitudes of mars concentrations of cl fe h k si and th have been determined to tens of centimeter depths as mass fractions with reasonable confidence comparing such data with or normalizing them to in situ compositional data is difficult due to issues such as dramatic differences in spatial resolution difficulties in convolving densities abundances and compositions of different regolith components and a limited number of elements observed in common we address these concerns in the context of the grs using si at pathfinder to normalize remote data in addition we determine representative in situ compositions for spirit both with and without columbia hills rocks opportunity and viking 1 landing sites using grs derived h content to hydrate the soil component our estimate of the si mass fraction at pathfinder with 13 areal fraction of rocks is 21 the composition of major elements such as si and fe is similar across the four landing sites while minor elements show significant variability areal dominance of soil at all four landing sites causes representative compositions to be driven by the soil component while proportionally large uncertainties of bulk densities dominate the net uncertainties grs compositional determinations compare favorably with the in situ estimates for cl and k and for si by virtue of the normalization however the grs determined fe content at each landing site is consistently higher than the in situ value

estimation of rupture propagation direction and strong motion generation area from azimuth and distance dependence of source amplitude spectra strong motion generation areas which reproduce ground motions in 0 2 to 10hz were estimated using the empirical green s function method this strong motion generation area was somewhat smaller than the total rupture area and coincident with the area of asperities derived from heterogeneous slip distributions estimated by waveform inversions using lower frequencies 1hz we confirmed that the azimuth and distance dependence of observed source amplitude spectra in the near source area i e rupture directivity effects were controlled by rupture propagation style and size of the strong motion generation area we found that the source displacement spectra at stations in forward rupture propagation directions had higher corner frequencies and steeper high frequency decays compared with stations in sideways directions stations in backward directions had opposite tendencies different relationships between size and average corner frequencies of the strong motion generation area were proposed for unilateral and bilateral ruptures with radial propagation

broadband kinematic stochastic simulation of an earthquake source a refined procedure for application in seismic hazard studies to carry out a realistic simulation of earthquake strong ground motion for applied studies one needs an earthquake fault source simulator that can integrate most relevant features of observed earthquake ruptures a procedure of this kind is proposed that creates a broadband kinematic source model at lower frequencies the source is described as propagating slip pulse with locally variable velocity the final slip is assumed to be a two dimensional 2d random function at higher frequencies radiation from the same running strip is assumed to be random and incoherent in space the model is discretized in space as a grid of point subsources with certain time histories at lower frequencies a realistic shape of source spectrum is generated implicitly by simulated kinematics of slip pulse propagation at higher frequencies the original approach is used to generate signals with spectra that plausibly approximate the prescribed smooth far field source spectrum this spectrum is set on the basis of the assumedly known regional empirical spectral scaling law and subsource moment rate time histories are conditioned so as to fit this expected spectrum for the random function that describes final slip over the fault area lognormal probability distribution of amplitudes is assumed on the basis of exploratory analysis of inverted slip distributions similarly random functions that describe local slip rate time histories are assumed to have lognormal distribution of envelope amplitudes in this way one can effectively emulate expressed asperities of final slip and occasional occurrence of large spikes on near source accelerograms a special procedure is proposed to simulate the spatial coherence of high frequency fault motion this approach permits the simulation of fault motion plausibly at high spatial resolution fulfilling the prerequisite for simulation of strong motion in the vicinity of a fault a particular realization sample of a source created in a simulation run depends on several random seeds and also on a considerable number of parameters their values can be selected so as to take into account expected source features they can also be perturbed to examine the source related component of uncertainty of strong motion the proposed approach to earthquake source specification is well adapted to the study of deterministic seismic hazard it may be used for simulation of individual scenario events or suites of such events as well as for analysis of uncertainty for expected ground motion parameters from a particular class of events examples are given of application of the proposed approach to strong motion simulations and related uncertainty estimation

annual to decadal morphodynamics of the foredune system at greenwich dunes prince edward island canada the purpose of this study was to quantify relationships between season sediment availability sediment transport pathways and beach foredune morphology at greenwich dunes pei this was done for periods ranging from a few days to multiple decades using erosion pins bedframe measurements annual surveys and digital photogrammetry using historical aerial photographs the relative significance of seasonal annual processes versus response of the foredune system to broader geomorphic controls e g relative sea level rise storms etc was also assessed the data show that there are clear seasonal differences in the patterns of sand supply from the beach to the foredune at greenwich and that there are differences in sediment supply to the foredune between the east and west reaches of the study area resulting in ongoing differences in foredune morphology they also demonstrate that models that incorporate wind climate alone or even models that include other factors like beach moisture would not be able to predict the amount of sediment movement from the beach to the foredune in this environment unless there were some way to parameterize system morphology especially the presence or absence of a dune ramp finally the data suggest that the foredune can migrate landward while maintaining its form via transfers of sediment from the stoss slope over the crest and onto the lee slope although the rate of foredune development or recovery after disturbance changes over time due to morphological feedback the overall decadal evolution of the foredune system at greenwich is consistent with and supports the davidson arnott 2005 conceptual model of dune transgression under rising sea level copyright 2012 john wiley sons ltd

moment tensor and rupture model for the 1949 olympia washington earthquake and scaling relations for cascadia and global intraslab earthquakes we reanalyzed the 13 april 1949 olympia washington earthquake by using digitized records and first motion polarities from long period seismograms the moment tensor mechanism is normal faulting with a down dip trending t axis similar in style to other cascadia intraslab earthquakes the total seismic moment is 1 3 1026 dyne cm m w 6 7 and the hypocenter depth is 60 km additional inverse modeling for the kinematic rupture process assuming the steeply east dipping fault plane from the moment tensor resulted in a slightly higher total moment of 1 9 1026 dyne cm m w 6 8 the earthquake ruptured to the south with at least two subevents the combined area of asperities and seismic moment for the 1949 earthquake was compiled with those from the 1965 seattle tacoma and the 2001 nisqually earthquakes and with those from japan and mexico to develop a source scaling relation separate from shallow global strike slip earthquakes we infer that deeper intraslab earthquakes have a significantly smaller combined area of asperities than those compiled for shallower strike slip earthquakes with the same seismic moment this difference in rupture area leads to a 3 to 5 fold increase in stress drop for earthquakes with seismic moments between 1024 and 1028 dyne cm

osl based lateral progradation and aeolian sediment accumulation rates for the apalachicola barrier island complex north gulf of mexico florida article i nfo vertical sediment cores in five separate beach ridge complexes along the north east gulf of mexico coast were recovered and dated using optically stimulated luminescence osl dating of quartz these are located on cape san blas csb little st george island lsgi richardson s hammock rh st joseph peninsula sjp and saint vincent island svi all of these landforms are coastal barrier systems situated along a 100 km stretch of the florida panhandle u s a two samples were collected for dating from each core ridge accumulation rates rar associated with lateral progradation were calculated from the dated samples we also determined average sediment accumulation rates asar for two intervals within each sediment core all osl ages within the sediment cores were found to be in stratigraphic order or in a few cases statistically indistinguishable moreover all dated ridges were found to be in correct temporal sequence based on their geomorphic positions rapidly accreted sequences were found to be backed by st joseph bay in the western region of the study area more slowly accreted sequences were associated with the more eastern stretches of the study area backed by st vincent sound and apalachicola bay our asar results are in accord with an australian study of modern dune accumulation perhaps our most important finding is that in the barrier island environments of this north eastern gulf coast region aeolian sedimentation continues well after full vegetative cover develops and stranding of landward ridges takes place this confirms our similar earlier observation on svi lopez and rink 2008 we find that up to approximately one order of magnitude lower sedimentation rates occur after an initial period of more rapid aeolian accumulation for the vertical intervals studied in foredune ridges lateral progradation rates of ridge sequences were highly variable within the study area ranging from 92 to 848 m 100 years but we did find agreement between some of our slower ridge accumulation rates and those in other areas of florida and around the world determined using osl and 14 c dating we conclude that osl may be used in a regional context to establish variation in progradation rates and aeolian accumulation that varies among systems

impact of atmospheric circulation patterns on coastal dune dynamics nw spain article i nfo dunes in temperate latitudes have experienced a significant stabilization in recent times essentially as a conse quence of the expansion of dense vegetation cover yet the causes for this gradual stabilization as well as the causes promoting antecedent aeolian mobilization remainpoorlyunderstood the traba coastal dune field located in nw spain was examined to explore the causes inducing aeolian activity and subsequent stabilization since 1940 morphological changes were identified through the combination of aerial photographs and geophysical techniques local wind field regimes were simulated using a regional climate model to obtain the variability of the most relevant modes of atmospheric circulation in the north atlantic and european regions north atlantic oscillation nao eastern atlantic ea and scandinavian scand this allows us to identify the impact of these circulation modes over dune dynamics results document an episode of aeolian activity during the 1950s followed by a gradual stabilization and fixation of the dune coincident with a decrease on storm and wind inten sity yet aeolian sand movement remained active insmall areas blowouts occurring mainly during the summer ne winds associated with a negative phase of the ea explain the movement of sand within the dune field under favorable conditions of sand supply on the other hand sand supply to the dune field from the beach was promoted by nw winds coincident with the summer negative phase of nao during winter the negative nao favored frequent sw winds associated with the passage of intense storms which in turn explain sand remobilization from the beach making sediment available for the nw winds to blow inland with this work it is proven that to understand past and future aeolian activity requires critical consideration of the variability and impact of the two principal modes of atmospheric circulation in the north atlantic nao and ea the scand mode explaining alowerpercentageofthelocalwind fieldvariabilitywasalsoincludedtoachievehigher significance levels of explained variance

episodic coastal dune development in the taean peninsula and anmyeon island korea during the mid to late holocene the episodic nature of coastal dune development has been widely identified in many dune areas over the world what causes such episodicity is still hotly debated sea level change climatic change and human impact have widely been reported as the main forcings though there is no agreement yet upon which factors are critical this research provides some evidence that sea level fluctuation and climatic factors controlled the episodic dune building together based upon optically stimulated luminescence osl dune ages on the west coast of korea the newly obtained and published osl dune ages on the west coast of the taean peninsula and anmyeon island korea indicate the six main periods of dune building 5 5 4 3 1 5 1 3 1 1 and 0 7 ka they correlate with evidence of colder climate in east asia that imply stronger dune forming winds during the winter under the influence of a more intense siberian high they also correlate with periods of higher sea level over the present one with fluctuations thus episodic dune activity along the west coast of the korean peninsula during the mid to late holocene appears to be linked to stronger winter winds capable of moving sand from the beach to the foredune ridges with short term fluctuations during the high stands copyright 2009 john wiley sons ltd

response of wave dominated and mixed energy barriers to storms wave dominated and mixed energy barriers are extremely dynamic landforms responding to processes operating over a spectrum of time scales ranging from daily to monthly fluctuations related to storm and post storm conditions to century to millennium scale evolution driven by relative sea level change two types of storms are of particular relevance warm core tropical and cold core extratropical cyclones both are responsible for generating very large waves highly energetic surf zone dynamics and sediment transport elevated inshore water levels and extensive morphological responses all cyclones are affected by climate change which governs their frequency intensity and tracks barrier storm response is primarily governed by maximum storm runup and barrier morphology as conceptualised in abby sallenger s storm impact scale model sallenger 2000 this model defines four storm impact regimes and includes erosive as well as accretionary responses on the erosion side the swash regime drives bar and berm flattening the collision regime is marked by dune scarping and beach lowe the overwash regime leads to dune scouring and channel incision and the inundation regime may result in barrier destruction on the deposition side storm berms and beach ridges may form and accrete in the swash and collision regimes localised vertical beach and barrier accretion are associated with the collision and overwash regimes and washover deposition takes place in the overwash and inundation regimes site specific factors play a key role in moderating the morphological response and include storm characteristics type duration and track longshore sediment supply upwelling downwelling currents coastal setting and inner shelf topography the response of a barrier to a tropical or extratropical cyclone can however not be considered in isolation and has to be appreciated in a longer temporal context involving morphological preconditioning due to antecedent wave and water level conditions additionally a simple process response approach of the cause and effect type is inappropriate and a more complex conceptual framework involving thresholds feedbacks resilience and vulnerability will need to be adopted a useful way to visualise and conceptualise more complex storm behaviours and the longer term vulnerability of barriers is the resilience trajectory which maps out the changes in barrier geometry elevation and width over various time scales from weeks to years or even longer and under varying forcing conditions including changes in storminess and sea level rise an increased understanding of barrier response to storms and sequences of storms is required to better quantify long term barrier response to climate change high resolution and comprehensive decadal records of barrier response to storms are a prerequisite to achieve this ambition linking site specific coastal settings hydrodynamic drivers and morphological responses and allowing the recognition of recovery and impact dominated phases the enhanced insights in barrier response to extreme events must then be incorporated into improved coastal response models to help predict the impacts of future climate change on wave dominated and mixed energy barriers around the world 2013 elsevier b v

attenuation relations of strong ground motion in japan using site classification based on predominant period a spectral acceleration attenuation model for japan is presented in the present study the data set includes a very large number of strong ground motion records up to the 2003 off tokach main and aftershocks site class terms instead of individual site correction terms are used the site classes of recording stations are from a recent study on site classification for strong motion recording stations in japan according to a classification scheme that has been used in japanese engineering design the use of site class terms enables tectonic source type effects to be identified and accounted for in the present model the effects of a faulting mechanism for crustal earthquakes also are accounted for for crustal and interface earthquakes a simple form of an attenuation model with respect to distance is able to capture the main strong motion characteristics and achieves unbiased estimates for subduction slab events a simple distance modification factor is employed to achieve plausible and unbiased predictions the effects of source depth tectonic source type and faulting mechanism of crustal earthquakes are significant the need for magnitude squared terms is evaluated and the use of magnitude squared terms reduces the interevent error further

quantitative morphology of rocks at the mars pathfinder landing site 1 we adapt and test a standard terrestrial technique of assessing morphology quantitatively for use with sites on mars based on two dimensional equations and particle outlines whereby images of particles obtained remotely may yield dimensionless numerical shape and roundness values consistent with previous knowledge of the lithology and sedimentary transport history our test site was the particle rich rock garden at the mars pathfinder landing site a location where the primary geologic processes and lithology have been determined by other means a total of 575 particles were assessed in terms of size sphericity elongation and roundness qualitative roundness was determined for 460 particles particles are mostly pebble to cobble sized and have an average sphericity of 0 75 elongation of 0 63 and relative roundness of 0 083 69 of particles are subangular or subrounded particle sphericity is unimodal with a size sphericity profile matching trends for terrestrial populations of similar lithology and elongations nearly identical to those for particles at vikings 1 and 2 this matches the predictions for a site with the single overall lithology implied from other analyses roundness data indicate one or possibly two particle populations representing the primary processes that likely affected particle roundness most strongly impact and catastrophic flooding finally we tested a hypothesis suggesting that darker smaller more angular particles comprise a population transported through impact cratering while larger less dark more rounded particles are associated with catastrophic flood transport the opposite result is seen larger particles throughout the rock garden are more angular than smaller ones

shoreface sand supply and mid to late holocene aeolian dune formation on the storm dominated macrotidal coast of the southern north sea abstract although pulses of coastal dune development in the course of the holocene have been attributed to variations in the availability of sand to modulation of sand supply by sea level change and to changes in wind conditions identifying the processes driving such pulses has been rather elusive the shore deposits bordering the tide and storm wave dominated southern north sea evince complex mid to late holocene stratigraphy and sediment heterogeneity these deposits include a unique 7 km long 0 3 0 6 km wide and up to 7 m high aeolian sand unit the ghyvelde dune occurring astride the french belgian border in an apparently anomalous inland location the dune overlies and is surrounded by tidal sandy and muddy deposits incorporating freshwater peat data from four mechanical cores and eight auger holes and three radiocarbon ages and one osl age suggest that this inland dune was part of an ancestral north sea sand flat and mudflat environment confronting the dune stratigraphy with the prevailing tide and storm controlled dynamics of shoreline progradation in this area indicates that dune formation occurred under a pulse of abundant sand supply resulting from the attachment to a mid holocene north sea tidal flat shore of a shoreface tidal bank under repeated storms this mode of onshore sand supply generates extremely rapid progradation up to 1 km over a century of the sand flat shore the surface of which serves as a large aeolian fetch zone for active backshore dune accumulation while parts of this surface trap locally significant amounts of mud that are subsequently fossilised by aeolian sand the potential influence of sea level and storminess in modulating the timing of shoreface sand supply and late holocene coastal dune development in the southern north sea reported in studies from other areas remains to be established

luminescence dating applications in geomorphological research abstract chronological control remains critical to the interpretation of environmental change and to establishing long term rates of geomorphological processes radiocarbon dating will continue to be the central technique for age assessment of carbon bearing sediments deposited in the last ca 40 ka but alternative absolute dating strategies are required for older or non carbon bearing sediments they include uranium series dating of precipitated sediments k ar and ar ar dating of primary volcanic materials and cosmogenic isotopic dating of surface exposure ages an additional family of methods collectively termed luminescence techniques is increasingly providing a basis for the age assessment of detrital sedimentary deposits these methods directly date the deposition of detrital mineral grains typically quartz and feldspar and have been demonstrated to provide accurate deposition chronologies for up to 800 ka although 150 ka is more typical in the past decade a subset of luminescence techniques which employ optical sample stimulation methods called optical dating has made it possible to date samples from a much wider range of depositional systems given that the methods directly date sedimentation they allow direct assessment of depositional dynamism in numerous terrestrial and subaqueous including marine sedimentary systems and have demonstrated particular potential in the elucidation of chronologies from aeolian dune and loess fluvial colluvial coastal and volcaniclastic environments this paper provides a summary of the principles of the luminescence especially optical dating methods and shows how recent developments specifically single aliquot dating procedures have dramatically enhanced the scope and potential of the method the luminescence techniques are increasingly being incorporated into a wide range of geomorphological studies which seek to establish the nature of landscape changes over the past interglacial glacial cycle and beyond

chemical multispectral and textural constraints on the composition and origin of rocks at the mars pathfinder landing site rocks at the mars pathfinder site are probably locally derived textures on rock surfaces may indicate volcanic sedimentary or impact generated rocks but aeolian abration and dust coatings prevent unambiguous interpretation multispectral imaging has resolved four spectral classes of rocks gray and red which occur on different surfaces of the same rocks pink which is probably soil crusts and maroon which occurs as large boulders mostly in the far field rocks are assigned to two spectral trends based on the position of peak reflectance the primary spectral trend contains gray red and pink rocks maroon rocks constitute the secondary spectral trend the spatial pattern of spectral variations observed is oriented along the prevailing wind direction the primary spectral trend arises from thin ferric coatings of aeolian dust on darker rocks the secondary spectral trend is apparently due to coating by a different mineral probably maghemite or ferrihydrite a chronology based on rock spectra suggests that rounded maroon boulders constitute the oldest petrologic unit a flood deposit succeeded by smaller cobbles possibly deposited by impact and followed by aeolian erosion and deposition nearly linear chemical trends in alpha proton x ray spectrometer rock compositions are interpreted as mixing lines between rock and adhering dust a conclusion supported by a correlation between sulfur abundance and red blue spectral ratio extrapolations of regression lines to zero sulfur give the composition of a presumed igneous rock the chemistry and normative mineralogy of the sulfur free rock resemble common terrestrial volcanic rocks and its classification corresponds to andesite igneous rocks of this composition may occur with clastic sedimentary rocks or impact melts and breccias however the spectral mottling expected on conglomerates or breccias is not observed in any apxs analyzed rocks interpretation of the rocks as andesites is complicated by absence of a 1 m pyroxene absorption band plausible explanations include impact glass band masking by magnetite or presence of calcium and iron rich pyroxenes and olivine which push the absorption band minimum past the imager s spectral range the inferred andesitic composition is most similar to terrestrial anorogenic icelandites formed by fractionation of tholeiitic basaltic magmas early melting of a relatively primitive martian mantle could produce an appropriate parent magma supporting the ancient age of pathfinder rocks inferred from their incorporation in hesperian flood deposits although rocks of andesitic composition at the pathfinder site may represent samples of ancient martian crust inferences drawn about a necessary role for water or plate tectonics in their petrogenesis are probably unwarranted

the 1993 kushiro oki japan earthquake a high stress drop event in a subducting slab a spatial slip distribution of the 1993 kushiro oki earthquake mw 7 6 is undoubtedly constrained using near field data and the detailed aftershock distribution this earthquake has peculiar features in that the slip on the fault plane is restricted within an extremely small area about 40 km 20 km between the upper and lower planes of the double seismic zone in the subducting slab beneath hokkaido the total seismic moment averaged slip and stress drop in this area are 3 3 1020 nm 5 5 m and 4 2 107 pa respectively this earthquake indicates that the region of the slab between the planes of the double seismic zone beneath hokkaido is strong enough to sustain a stress of about 4 107 pa the slip motion of this event is consistent with retrograde slab migration along the southern kuril trench and may represent a process by which retrograde motion of subducting slabs could occur

decadal changes in north atlantic atmospheric circulation patterns recorded by sand spits since 1800 ce abstract present day coastal barriers represent around 15 of the world s oceanic shorelines and play an important role as early warning indicators of environmental change among them wave dominated barriers are dynamic landforms that tend to migrate landward in response to storms and sea level change high rates of sediment supply can locally offset the global retrogradation trend providing valuable records of past environmental change occurring on transgressive coasts however geochronological control limits the temporal resolution of such records to millennial or centennial timescales and the decadal or even faster response of wave built barriers to historical climate changes is therefore poorly understood in this study we show that shoreline dynamics of sand spits reconstructed from old cartographic documents has been synchronous on both margins of the north atlantic ocean since about 1800 ce spit growth accelerated drastically during three periods lasting about 15 years characterised by positive north atlantic oscillation nao and negative east atlantic west russia ea wr atmospheric circulation patterns these changes are in phase with periods of increased volcanic activity we use a high resolution wave hindcast 1948 2014 ce in a reference area to confirm the association between nao and ea wr as a proxy for offshore and nearshore wave height and for associated longshore sediment transport lst involved in spit growth a 24 month lagged correlation between sediment transport and volcanic aerosol optical thickness concentration of ashes in the atmosphere is observed suggesting that spit shoreline dynamics at the decadal timescale is partially forced by external climate drivers via cascading effects on atmospheric circulation patterns and wave climate our results imply that nao variability alone is not sufficient to understand the evolution of wave built coastal environments the associated sediment record can be used to reconstruct multi decadal variability of other climate patterns

assessment of temporal changes in coastal sand dune environments using the log hyperbolic grain size method three cores 9 m long recovered from late holocene coastal sand dunes in northumberland north eastern england were examined stratigraphically and dated by the infrared stimulated luminescence irsl method to the time period between the medieval warm period mwp 900 1200 ad and little ice age lia 1550 1800 ad grain size variability and caco 3 content were determined at 10 mm intervals throughout parts of the cores the sahara computer program was used to plot the log hyperbolic distribution lhd of grain size spectra from different stratigraphic levels and estimate the lhd s statistical components core samples plot variously in the depositional and erosional domains of the hyperbolic chi vs xi shape triangle which describes components of sediment sorting depositional and erosional phases discriminated within the lhd s shape triangle cannot readily be resolved from core stratigraphies or correlated between cores irsl dates from single cores show a clustering about the period 1430 1540 between the dated horizons dunes accreted at 0 02 0 05 m year 1 enabling the timing of excursions in and to be estimated these excursions which can be resolved to the subannual level between the dated horizons may be related to deposition by episodic storms or storm surges in the north sea region which is supported by historical documentary evidence this innovative use of the lhd method and its derived statistics can be used successfully to describe temporal trends in coastal depositional environments and identify likely storm events in dune sediment records

optically stimulated luminescence dating of young sediments a review optically stimulated luminescence osl dating of young 1000 years sediments is used increasingly in a wide variety of late holocene studies as a mean of establishing contemporary sedimentation rates or the timing of sediment deposition this paper provides a summary of the basic principles of osl dating outlines the problems specific to the dating of young material and then uses recent applications to young sediments to illustrate the greatly increased scope and potential of the method in geomorphology and the geology of recent deposits the overall reliability of this new generation of osl ages is examined by comparing where possible osl ages with independent age control it is concluded that the osl ages are accurate in that there is no evidence for systematic over or under estimation it is our conclusion that osl dating should be regarded as a reliable chronological tool for determining the time of deposition of water lain sediments from the coastal zone and aeolian deposits from both coastal and inland environments our conclusion is supported by the growing popularity of osl dating in geomorphology and geology

reconstruction of holocene coastal foredune progradation using luminescence dating an example from the świna barrier southern baltic sea nw poland abstract two sandy spits on the wina barrier wolin and uznam provide a very detailed succession of holocene coastal foredunes and dunes and are regarded as key sites along the southern baltic sea coast optically stimulated luminescence osl dating is proven to be a powerful tool for the reconstruction of holocene coastal spit evolution and foredune accretion quartz extracted from the coastal sediments in the study area provides excellent properties for osl dating the osl age from the innermost dune indicates that spit development of the wina barrier started immediately after rapid sea level rise of the littorina transgression decelerated at 6 6 ka a significant change in the foredune progradation rate occurred during the late subatlantic transgression at 1 2 ka 800 ad when migration rates decreased from 2 6 0 7 m a 1 to 1 3 0 4 m a 1 progradation accelerated again during the little ice age between 1550 and 1850 ad the systematic dating of 28 samples reveals six hiatuses during foredune succession at 2100 bc 900 bc 200 bc 200 ad 600 ad 1000 ad and 1600 ad the timing of these hiatuses correlates with the phases of transgressive dune development in the surrounding area troszyn and wina and with phases of increased aeolian activity in other parts of north and west europe we conclude that four of these phases of foredune erosion instability and aeolian sediment mobilisation were caused by general climate shifts to cooler and stormier conditions at 2200 bc 900 bc 600 ad and at 1600 ad the latter corresponding to the little ice age the period of increased aeolian activity around 1000 ad is probably to a phase of intensive forest clearance in central europe in contrast the systematic foredune accretion and foredune plain growth correlates to periods of positive sediment budget milder and calmer climate and an intact vegetation cover

inslab earthquakes of central mexico peak ground motion parameters and response spectra we developed equations to predict pseudoacceleration response spectra 5 damping peak ground acceleration and peak ground velocity at free field rock sites for intermediate depth normal faulting inslab earthquakes of central mexico the data set comprises 16 earthquakes 5 2 m w 7 4 35 h 138 km recorded at local and regional distances r 400 km it represents a homogeneous catalog with respect to tectonic regime fault mechanism and soil class our results show larger amplitudes in the epicentral area from inslab events than from interplate events a consequence of higher stress drops during the former type of earthquakes peak ground accelerations from moderate to large m w 6 0 inslab events significantly exceed those from interplate events with similar magnitude reaching almost three times for the largest events the ground motion due to inslab events however decays faster than for the thrust events our results are in reasonable agreement with other studies based on japanese and the worldwide data

source model of the 1995 hyogo ken nanbu earthquake and simulation of near source ground motion the 1995 hyogo ken nanbu earthquake struck the heavily populated kobe and adjacent cities in western japan more than 6400 people were killed and more than 150 000 buildings were destroyed the characteristics of mainshock ground motions in the heavily damaged area are needed to understand how buildings and bridges performed and why they reached failure unfortunately very few strong ground motions were recorded in the heavily damaged area during the mainshock in this study we attempt to estimate mainshock ground motions by using the em pirical green s function method egf method first we assume an initial source model with the asperities based on the rupture process obtained by inversion of strong ground motion records for simplicity we consider each asperity as a sub event with uniform stress drop in a finite extent then the initial model was improved by matching the synthetic and observed ground motions using a trial and error pro cedure the final model consists of three subevents subevent 1 with stress drop of 163 bars under the akashi strait around the rupture starting point subevent 2 with stress drop of 86 bars under the nojima fault in awaji island and subevent 3 with stress drop of 86 bars under kobe finally we estimate strong ground motions using aftershock records at sites where the mainshock was not recorded the near source motions in kobe synthesized with the best fit model are characterized by two large pulses with a duration of 1 to 3 sec the pulses are caused by forward rupture directivity effects from subevents 1 and 3 peak horizontal acceleration and velocity of the synthesized motions at the heavily damaged sites are about 1000 cm sec 2 and 130 crrdsec respectively while those at a rock site in the near source region are about 300 crrdsec 2 and 60 cm sec

mineralogic and compositional properties of martian soil and dust results from mars pathfinder mars pathfinder obtained multispectral elemental magnetic and physical measurements of soil and dust at the sagan memorial station during the course of its 83 sol mission we describe initial results from these measurements concentrating on multispectral and elemental data and use these data along with previous viking snc meteorite and telescopic results to help constrain the origin and evolution of martian soil and dust we find that soils and dust can be divided into at least eight distinct spectral units based on parameterization of imager for mars pathfinder imp 400 to 1000 nm multispectral images the most distinctive spectral parameters for soils and dust are the reflectivity in the red the red blue reflectivity ratio the near ir spectral slope and the strength of the 800 to 1000 nm absorption feature most of the pathfinder spectra are consistent with the presence of poorly crystalline or nanophase ferric oxide s sometimes mixed with small but varying degrees of well crystalline ferric and ferrous phases darker soil units appear to be coarser grained compacted and or mixed with a larger amount of dark ferrous materials relative to bright soils nanophase goethite akaganeite schwertmannite and maghemite are leading candidates for the origin of the absorption centered near 900 nm in imp spectra the ferrous component in the soil cannot be well constrained based on imp data alpha proton x ray spectrometer apxs measurements of six soil units show little variability within the landing site and show remarkable overall similarity to the average viking derived soil elemental composition differences exist between viking and pathfinder soils however including significantly higher s and cl abundances and lower si abundances in viking soils and the lack of a correlation between ti and fe in pathfinder soils no significant linear correlations were observed between imp spectral properties and apxs elemental chemistry attempts at constraining the mineralogy of soils and dust using normative calculations involving mixtures of smectites and silicate and oxide minerals did not yield physically acceptable solutions we attempted to use the pathfinder results to constrain a number of putative soil and dust formation scenarios including palagonitization and acid fog weathering while the pathfinder soils cannot be chemically linked to the pathfinder rocks by palagonitization this study and mcsween et al 1999 suggest that palagonitic alteration of a martian basaltic rock plus mixture with a minor component of locally derived andesitic rock fragments could be consistent with the observed soil apxs and imp properties

intense storm activity during the little ice age on the french mediterranean coast understanding long term variability in the frequency of intense storm activity is important for assessing whether changes are controlled by climate evolution understanding this variability is also important for predicting present and future community vulnerability and economic loss our ability to make these assessments has been limited by the short less than 50 years instrument record of storm activity storm induced deposits preserved in the sediments of coastal lagoons offer the opportunity to study the links between climatic conditions and storm activity on longer timescales in this study we present a record of these extreme climatic events that have occurred in the french mediterrannean coast over the past 1500 years the identification of these extreme events is based on the analysis of sediment cores from gulf of aigues mortes lagoons that contain a specific sedimentary and geochemical signature associated with intense storms overwash deposits do not show any evidence of intense storm landfalls in the region for several hundred years prior to the late 17th century a d the apparent increase in intense storms around 250 years ago occurs during the latter half of the little ice age a time of lower continental surface temperatures comparison of the sediment record with palaeoclimate records indicates that this variability was probably modulated by atmospheric dynamics the apparent increase of the superstorm activity during the latter half of the little ice age was probably due to the thermal gradient increase leading to enhanced lower tropospheric baroclinicity over a large central atlantic european domain and leading to a modification of the occurrence of extreme wind events along the french mediterranean coast a complete understanding of the relationship between climate fluctuations storm activity and the coastal response will be crucial to predicting the impacts of future climate change

luminescence dating of holocene sedimentary deposits on romo a barrier island in the wadden sea denmark this study presents an optically stimulated luminescence osl based chronology for the evolution of the barrier island romo and related back barrier lagoon deposits in the danish wadden sea the chronology is constructed using 78 quartz osl ages obtained using a single aliquot regenerative dose sar protocol samples were retrieved from seven sediment cores each up to 25 m long taken from locations on the island and within the back barrier lagoon the reliability of the osl results is assessed using preheat plateaus thermal transfer tests and dose recovery measurements and by comparison with independent age control the osl ages compare favourably with three 14c age estimates and range between 220 20 and 15 800 1200 years romo appears to have developed as a progradational barrier system and the island appeared for the first time approximately 8000 years ago it then gradually expanded towards the west north and south as a result of an abundant sediment supply luminescence dating is concluded t

the 1994 hokkaido toho oki earthquake sequence the complex activity of intra slab and plate boundary earthquakes abstract we study the complex activity of the 1994 hokkaido toho oki earthquake sequence based on strong motion records and teleseismic data first we examine s wave acceleration spectra of the aftershocks by comparison with that of the main shock the main shock m w 8 2 an intra slab earthquake has been characterized by strong radiation of high frequency seismic waves from different shapes of the spectral ratios of the aftershocks to the main shock the aftershocks can be classified into three types next we redetermine the source parameters focal depth seismic moment and source duration for larger events by waveform modeling of teleseismic p waves the hypocentral locations and stress drops estimated from these parameters show that the three aftershock types fall into different categories of subduction zone earthquakes intra slab relatively deep plate boundary and shallow plate boundary earthquakes finally we estimate source spectra for three different earthquake categories after correcting s wave acceleration spectra for the attenuation effect the source spectrum at high frequencies is modeled by using a high cut filter whose parameters are a cut off frequency f max and a decay rate the source spectrum of intra slab earthquakes has high f max and small decay rate due to this feature and the high stress drop intra slab earthquakes radiate strong high frequency seismic waves through this study we demonstrate that the 1994 hokkaido toho oki earthquake sequence has the complex activity of intra slab and plate boundary earthquakes

proxy records of holocene storm events in coastal barrier systems storm wave induced markers abstract extreme storm events in the coastal zone are one of the main forcing agents of short term coastal system behavior as such storms represent a major threat to human activities concentrated along the coasts worldwide in order to better understand the frequency of extreme events like storms climate science must rely on longer time records than the century scale records of instrumental weather data proxy records of storm wave or storm wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia this review provides a detailed state of the art compilation of the proxies available from coastal barrier systems to reconstruct holocene storm chronologies paleotempestology the present paper aims i to describe the erosional and depositional processes caused by storm wave action in barrier and back barrier systems i e beach ridges storm scarps and washover deposits ii to understand how storm records can be extracted from barrier and back barrier sedimentary bodies using stratigraphical sedimentological micro paleontological and geochemical proxies and iii to show how to obtain chronological control on past storm events recorded in the sedimentary successions the challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm chronologies using these various proxies are discussed and future research prospects are outlined

aftershock distribution of the october 4 1994 mw8 3 kurile islands earthquake determined by a local seismic network in hokkaido japan on october 4 1994 an earthquake with magnitude mw8 3 occurred in the western part of kurile islands at 43 42 n 146 81 e and 33 km in depth the hypocenter parameters were determined by hokkaido university in japan aftershocks following this remarkable event were located using data from a local seismic network operated by hokkaido university we found that most of the aftershocks occurred 1 on the fault plane of the mainshock 2 in the subducting plate around the fault plane of the mainshock and 3 in the focal area of the largest aftershock which occurred on october 9 with mw7 3 both 2 and 3 were not active immediately after the mainshock considering the time sequence of the aftershock activity we identified one of the nodal planes of the harvard quick cmt solutions as the fault plane of the mainshock the strike is almost parallel to the trench axis and the dip angle is near vertical it is obvious that this event is different from a low angle thrust type interplate earthquake the distribution of aftershocks strongly suggests that it is an intraplate event