micromorphlogy of recent and buried soils in a semi arid region of northwestern india abstract profiles of four recent soils and of eleven soils buried under archaeological sites of known ages were investigated in an area between the ghaggar valley and the northern piedmont of the arawalli hills in northwestern india the principal approach was through study of micromorphology data were also obtained on mineralogies of several size fractions characteristics shared by the recent and buried soils indicate that essentially the same processes operated in their formation the oldest soils are buried under protohistoric sites and thus were formed at least 5000 years ago they are developed on sediments rich in sand sized mica flakes which indicate an alluvial origin others are buried beneath historic sites with ages ranging from 500 b c to 1500 a d these soils and the recent ones have a silt fraction low in mice major features of both buried and recent soils are attributed to biological activity reflected in extensive channeling and additions of excrements throughout profiles local distribution of clay silt and carbonates indicates translocation of these components furthermore the forms of calcitic features indicate modifications of various kinds evidence of biological activity as expressed in characteristics of the soils becomes progressively weaker from older to younger profiles soil development seems to have weakened over that period as well these changes are correlated with the decline with time in the proportions of mica flakes in coarse fractions the decline is attributed to lack of alluvial sedimentation since the protohistoric period and to greater transport and winnowing of sediments by wind we believe this has reduced fertility of the soils formed during the last 4000 years

surges around the hawaiian islands from the 2011 tohoku tsunami 1 the 2011 tohoku tsunami devastated the northeastern japan coasts and caused localized damage to coastal infrastructure across the pacific the tsunami resulted in strong currents around the hawaiian islands that led to closure of harbors and marinas for up to 38 h after its arrival we utilize a nonhydrostatic model to reconstruct the tsunami event from the seismic source for elucidation of the physical processes and inference of the coastal hazards a number of tide gauges bottom pressure sensors and adcps provided point measurements for validation and assessment of the model results in hawaii spectral analysis of the computed surface elevation and current reveals complex flow patterns due to multiscale resonance standing waves with 33 75 min period develop along the island chains while oscillations of 27 min or shorter are primarily confined to an island or an island group with interconnected shelves standing edge waves with periods 16 min or shorter which are able to form nodes on the reefs and inside harbors are the main driving force of the observed coastal currents resonance and constructive interference of the oscillation modes provide an explanation of the impacts observed in hawaii with implications for emergency management in pacific island communities

a high resolution micromorphological record of changing landscapes and climates on the western loess plateau of china during oxygen isotope stage 5 abstract the micromorphological characteristics of a continuous set of block samples from 24 38 m depth in a well section on jiuzhoutai mountain lanzhou china are described the shape of the magnetic susceptibility curve together with previously published radiocarbon luminescence and geomagnetic dates indicates that this sample set encompasses the whole of the last interglacial s1 palaeosol complex and extends into the overlying and underlying loess l1 and l2 units seven pedosedimentary units are recognised on the basis of trends in the bulk properties and the key micromorphological indicators excrements textural concentrations shell fragments and calcite and gypsum features high rates of loess deposition with significant cryogenic activity gypsum precipitation and only weak bioturbation characterised oxygen isotope stage ois 6 and ois 4 at lanzhou depositional rates were moderately high in ois 5d and 5b with slightly higher bioturbation and no significant cryogenesis or gypsum precipitation ois 5e 5c and 5a were marked by low rates of accretion more extensive bioturbation and limited leaching this reconstruction reflects the pedosedimentary responses to fluctuating dominances of monsoonal controls during this period of global climatic change comparison of earlier micromorphological results from sites to west and east of lanzhou along a dry to humid climatic gradient indicate a clear regional pattern with reduced loess accumulation rates and enhanced bioturbation and leaching in the humid east tianshui and xian clay translocation occurred only in ois 5e at xian the warmest and most humid site on the transect

neural network for tsunami and runup forecast 1 this paper examines the use of neural network to model nonlinear tsunami processes for forecasting of coastal waveforms and runup the three layer network utilizes a radial basis function in the hidden middle layer for nonlinear transformation of input waveforms near the tsunami source events based on the 2006 kuril islands tsunami demonstrate the implementation and capability of the network division of the kamchatka kuril subduction zone into a number of subfaults facilitates development of a representative tsunami dataset using a nonlinear long wave model the computed waveforms near the tsunami source serve as the input and the far field waveforms and runup provide the target output for training of the network through a back propagation algorithm the trained network reproduces the resonance of tsunami waves and the topography dominated runup patterns at hawaii s coastlines from input water level data off the aleutian islands

evaluation of velocity related approximations in the nonlinear shallow water equations for the kuril islands 2006 tsunami event at honolulu hawaii 1 the nonlinear shallow water equations nswe provide a model for long wave behavior commonly used in tsunami modeling problems in which the scale associated with the surface wavelength is much greater than the ocean depth this approximation allows for the derivation of the nswe under the assumptions that the pressure is hydrostatic and the horizontal velocity components uniform along the water column the present study uses current velocity data acquired by the kilo nalu near shore reef observatory acoustic doppler current profiler adcp on the south shore of oahu 21 288 n 157 865 w in the aftermath of the 2006 kuril tsunami to assess the validity of the nswe assumptions on the velocity components adcp measurements provide information on all three velocity components along the water column allowing the calculation of terms discarded in the nswe approximation containing temporal or vertical derivatives comparison of the relative magnitude of terms retained and neglected in the nswe reveals that in shallow waters 10 m the size of discarded terms remains smaller but approaches the order of magnitude of retained terms in the momentum equations not all terms present in the equations can be evaluated from the available data so verification of the assumptions investigated here represents a necessary but not sufficient condition for the validity of the nswe approximation to model tsunami waves in shallow coastal waters

contemporary rates of chemical denudation and atmospheric co2 sequestration in glacier basins an arctic perspective this paper presents new estimates of solute fluxes from five high arctic glacier basins in svalbard these estimates are combined with data from two other glacier basins to assess the effectiveness of chemical denudation on svalbard and to estimate rates of temporary or transient co2 drawdown we use a solute provenance model to partition solutes into marine aerosol atmospheric and crustal components and to estimate their annual fluxes crustally derived solute fluxes are equivalent to a mean chemical denudation rate of 350 meq m 2 a 1 for svalbard range 160 560 meq m 2 a 1 which lies within the global range of 94 4200 meq m 2 a 1 for 21 glacier basins in the northern hemisphere and is close to the continental average of 390 meq m 2 a 1 specific annual discharge is the most significant control upon chemical denudation in the glacierized basins and basin lithology is an important secondary control with carbonate rich and basaltic lithologies currently showing the greatest chemical denudation rates estimates of transient co2 drawdown are also directly associated with specific annual discharge and rock type on svalbard transient co2 drawdown lies in the range 110 3000 kg c km 2 a 1 whilst the range is 110 13000 kg c km 2 a 1 for the northern hemisphere glacial data set transient co2 drawdown is therefore usually low in the svalbard basins unless carbonate or basalt rocks are abundant the analysis shows that a large area of uncertainty in the transient co2 drawdown estimates exists due to the non stoichiometric release of solute during silicate hydrolysis silicate hydrolysis is particularly non stoichiometric in basins where the extent of glacierization is high which is most probably an artefact of high flushing rates through ice marginal and subglacial environments where k feldspars are undergoing mechanical comminution copyright 2000 john wiley sons ltd

tide gauge observations of 2004 2007 indian ocean tsunamis from sri lanka and western australia tide gauge data collected from sri lanka three stations and western australia eleven stations during the indian ocean tsunamis which occurred in december 2004 march 2005 july 2006 and september 2007 and incorporated five tsunamis were examined to determine tsunami behaviour during these events during the december 2004 tsunami maximum wave heights of 3 87 m and 1 75 m were recorded at colombo sri lanka and bunbury western australia respectively the results indicated that although the relative magnitudes of the tsunamis varied the tsunami behaviour at each station was similar this was due to the effect of the local and regional topography at all tide gauges the spectral energy corresponding to periods between 20 and 85 minutes increased during the tsunami the sea level data obtained from the west and south coasts of sri lanka colombo and kirinda indicated the importance of wave reflections from the maldives island chain which produced the maximum wave two to three hours after the arrival of the first wave in contrast trincomalee on the east coast did not show evidence of a reflected wave similarly along the west coast of australia the highest waves occurred 15 hours after the arrival of the first wave here based on travel times we postulated that the waves were reflected from the mascarene ridge and or the island of madagascar reflected waves were not present in the 2006 tsunami where the primary waves propagated away from topographic features one of the main influences of the tsunami was to set up oscillations at the local resonance frequency because sri lanka and western australia have relatively straight coastlines these oscillations were related to the fundamental period of the shelf oscillation for colombo this corresponded to 75 minute period whereas in geraldton and busselton australia the four hour period was most prominent at jurien bay and fremantle the resonance period was 2 7 hours

micromorphological variation of the s 1 paleosol across northwest china abstract a micrornorphological approach based upon sets of closely spaced thin sections taken from three sites located along a climatic and depositional gradient has been utilised to reconstruct the sequence of pedogenic and sedimentary events leading to the development of the s1 paleosol in northwest china two main pedosedimentary stages related to regional changes in monsoonal controls are evident at each site although the resolution processes and resultant features vary in a manner reflecting differences in climate and rates of loess deposition around xining in the west where loess accumulation rates were high and pedogenic processes were restricted to shallow leaching and limited bioturbation by the low rainfall s 1 comprises two discrete weakly developed paleosol units separated by a less pedogenically altered layer of loess in contrast at sites farther away from the loess source area in the more humid southeast s 1 is a thinner welded and more pedogenically developed unit dominated by the effects of extensive leaching bioturbation and sometimes even clay translocation processes

hydrochemistry as an indicator of subglacial drainage system structure a comparison of alpine and sub polar environments the anion compositions so 2 4 hco 3 and cl of runoff from the haut glacier d arolla switzerland and austre broggerbreen svalbard are compared to assess whether or not variations in water chemistry with discharge are consistent with current understanding of the subglacial drainage structure of warm and polythermal based glaciers these glacial catchments have very different bedrocks and the subglacial drainage structures are also believed to be different yet the range of anion concentrations show considerable overlap for so 2 4 and hco 3 concentrations of cl are higher at austre broggerbreen because of the maritime location of the glacier correcting so 2 4 for the snowpack component reveals that the variation in non snowpack so 2 4 with discharge and with hco 3 is similar to that observed at the haut glacier d arolla hence if we assume that the provenance of the non snowpack so 2 4 is the same in both glacial drainage systems a distributed drainage system also contributes to runoff at austre broggerbreen we have no independent means of testing the assumption at present the lower concentrations of non snowpack so 2 4 at austre broggerbreen may suggest that a smaller proportion of runoff originates from a distributed drainage system than at the haut glacier d arolla

nitrate production beneath a high arctic glacier svalbard natural environmental isotopes of nitrate and ammonium are used in conjunction with major ion chemistry and hydrological data to establish controls upon the biogeochemical cycling of nitrogen beneath a high arctic polythermal glacier midtre lovenbreen here high nitrate concentrations in subglacial meltwaters suggest that the subglacial environment may be furnishing nitrate in excess of that released from the snowpack and glacier ice isotopic values of 18ono3 suggest the provenance of such excess nitrate to be microbial in origin and 15nno3 indicates the source nitrogen compounds to have high 15n values relative to supraglacial runoff we address the nitrification of supraglacial ammonium the mineralization of organic nitrogen and the oxidation of geologic ammonium as potential sources of this additional nitrate mass fluxes of n compounds in a subglacial river and their 15n ratios indicate that the nitrification of supraglacial ammonium delivered to the glacier bed can account for much but not all of the excess nitrate the additional source most likely involves the mineralization of organic nitrogen although 15n values in rock samples suggest that the dissolution of rock derived ammonium cannot be discounted if large fractionation effects occur during dissolution our results therefore agree with previous catchment scale mass balance studies at the site which report a major internal loss of nh4 from the snowpack following melt however at the catchment scale the nh4 loss is greater than the excess of no3 observed in runoff indicating that microbial assimilation of ammonia into organic matter in a range of other habitats is also likely the identification of nh4 assimilation and nitrification further highlights the non conservative behaviour of nitrogen in glacial environments and testifies to the importance of microbially mediated reactions in the biogeochemical cycling of nitrogen in an environment that has until recently been regarded as biologically inert

an integrated approach to modelling hydrology and water quality in glacierized catchments the results are summarized of an integrated investigation of glacier geometry ablation patterns water balance meltwater routing hydrochemistry and suspended sediment yield the ultimate objective is to evaluate the assumptions of lumped two component mixing models as descriptors of glacier hydrology and to develop a semi distributed physically based model as an alternative the results of the study demonstrate that a reconstruction of probable subglacial drainage alignments can be achieved through a combination of terrain modelling based on estimated potential surface and dye tracing experiments recession curve analysis evidence of the seasonal instability of the englacial and subglacial electrical conductivities assumed in a mixing model evidence of the non conservative behaviour of water chemistry in the presence of suspended sediment and evidence of the seasonal evolution of the subglacial drainage system based on dye tracing all indicate that an alternative to a lumped static model of the hydrology is necessary the alternative presented in this paper is based on the combination of an energy balance model for surface melt which operates on an hourly time step and accounts for the changing spatial distribution of melt through the day as shading patterns change and routing procedures that transfer surface melt to moulins on the basis of glacier surface gradients then route water through reconstructed conduit systems using a hydraulic sewer flow routing procedure

links between short term velocity variations and the subglacial hydrology of a predominantly cold polythermal glacier the surface velocity of a predominantly cold polythermal glacier john evans glacier ellesmere island canada varies significantly on both seasonal and shorter time scales seasonal variations reflect the penetration of supraglacial water to the glacier bed through significant thicknesses of cold ice shorter term events are associated with periods of rapidly increasing water inputs to the subglacial drainage system earlyseason short term events immediately follow the establishment of a drainage connection between glacier surface and glacier bed and coincide with the onset of subglacial outflow at the terminus a mid season short term event occurred as surface melting resumed following cold weather and may have been facilitated by partial closure of subglacial channels during this cold period there is a close association between the timing and spatial distribution of horizontal and vertical velocity anomalies the temporal pattern of surface water input to the glacier and the formation seasonal evolution and distribution of subglacial drainage pathways these factors presumably control the occurrence of highwater pressure events and water storage at the glacier bed the observed coupling between surface water inputs and glacier velocity may allow predominantly cold polythermal glaciers to respond rapidly to climate induced changes in surface melting

nitrogen in rock occurrences and biogeochemical implications 1 there is a growing interest in the role of bedrock in global nitrogen cycling and potential for increased ecosystem sensitivity to human impacts in terrains with elevated background nitrogen concentrations nitrogen bearing rocks are globally distributed and comprise a potentially large pool of nitrogen in nutrient cycling that is frequently neglected because of a lack of routine analytical methods for quantification nitrogen in rock originates as organically bound nitrogen associated with sediment or in thermal waters representing a mixture of sedimentary mantle and meteoric sources of nitrogen rock nitrogen concentrations range from trace levels 200 mg n kg 1 in granites to ecologically significant concentrations exceeding 1000 mg n kg 1 in some sedimentary and metasedimentary rocks nitrate deposits accumulated in arid and semi arid regions are also a large potential pool nitrogen in rock has a potentially significant impact on localized nitrogen cycles elevated nitrogen concentrations in water and soil have been attributed to weathering of bedrock nitrogen in some environments nitrogen released from bedrock may contribute to nitrogen saturation of terrestrial ecosystems more nitrogen available than required by biota nitrogen saturation results in leaching of nitrate to surface and groundwaters and where soils are formed from ammonium rich bedrock the oxidation of ammonium to nitrate may result in soil acidification inhibiting revegetation in certain ecosystems collectively studies presented in this article reveal that geologic nitrogen may be a large and reactive pool with potential for amplification of human impacts on nitrogen cycling in terrestrial and aquatic ecosystems

small scale secondary caco3 accumulations in selected sections of the european loess belt morphological forms and potential for paleoenvironmental reconstruction eighteen important quaternary loess paleosoil sites have been studied across the european loess belt they included approximately 50 buried soils the over and or underlying loess and the present day surface soils where possible from the numerous types of secondary caco3 accumulations recognized only the small scale accumulations are discussed in this paper including calcified root cells caco3 hypocoatings needle fiber calcite powdery calcite coatings earthworm biospheroliths and calcite pseudomorphs on gypsum most of the features studied are found in the rhizosphere microecosystem each of these features showed a unique relationship with organic matter micro organism and plant distribution moisture and leaching processes for example the exceptional abundance of calcified root cells is an indicator of a long stability of soil surface during favorable climatic conditions needle fiber calcite is related to biomineralization of saprophytes in soils with sufficient moisture and decomposing organic matter the presence of powdery calcite coatings covering clay and mn coatings in non calcareous soils indicates a change from leaching to non leaching soil moisture regimes earthworm biospheroids provide arguments for a relative stability of the soil surface without rapid burial processes or drastic prolonged water stress finally gypsum pseudomorphs are indicators of changes in local climatic parameters in addition to a discussion of the genesis and the dynamics of the various accumulations several examples are given to show how these accumulations can be used as indicators of a changing environment such as renewed loess deposition the extent of drought or varying intensity of leaching during the year to conclude various forms of small scale secondary caco3 accumulations are common in the loess paleosoils and each type has the potential to contribute to a better understanding of the evolution of the paleoenvironment therefore it is proposed that their individual presence or absence throughout the pedostratigraphical levels and throughout the paleo topography should be recorded at all scales of observation

edge waves revisited abstract for edge waves on an infinite beach of constant slope comparison is made between the full linear solution and the shallow water approximation modifications to the shallow water edge wave dispersion relation accounting for an offshore shelf are obtained and compared with an earlier approximation a physically comprehensible description of edge waves is given using a geometrical optics approach leading to approximate expressions for their dispersion relation both shallow water and general depth are considered for the shallow water case comparison is made with the exact relation for an exponentially seaward decreasing slope finally the maximum possible edge wave amplitude is estimated by heuristic arguments

reply to the comment by shah on isotopic and micromorphological studies of late quaternary loess paleosol sequences of the karewa group inferences for palaeoclimate of kashmir valley

suspended sediment and phosphorus in proglacial rivers bioavailability and potential impacts upon the p status of ice marginal receiving waters this paper adopts standard tests developed in temperate catchment research to determine the total phosphorus tp and the algal available base extractable phosphorus naoh p content of a wide range of glaciofluvial sediments from the northern hemisphere we find that the tp content of these sediments is broadly similar to the p content of major rock types in earth s crust 230 670 gp g and so the tp yields of glacier basins may be high owing to the efficacy of suspended sediment evacuation by glacial meltwaters we show that this is best achieved where subglacial drainage systems are present the naoh p pool of the sediments is found to be low 1 23 gp g relative to the tp pool and also to the naoh p pool of suspended sediments in temperate non glacierized catchments this most probably reflects the restricted duration of intimate contact between dilute meltwaters and glacial suspended sediments during the ablation season thus despite the high surface area volume ratio of glacial suspended sediments the potential for p adsorption to mineral surfaces following release by dissolution is also low further sorption experiments and sequential extraction tests conducted using glacial suspended sediments from two svalbard catchments indicate that the generation of reactive secondary minerals e g fe and other hydroxides with a strong capacity to scavenge p from solution and thereby promote the continued dissolution of p may also be limited by the short residence times most p is therefore associated with poorly weathered calcite apatite rich mineral phases however we use examples from the svalbard glacier basins austre broggerbreen and midre lovenbreen to show that the high sediment yields of glaciers may result in appreciable naoh p loading of ice marginal receiving waters again the importance of subglacial drainage is highlighted as it produces a major episodic release of naoh p at midre lovenbreen that results in a yield 8 2 kg naoh p km2 year more than one order of magnitude greater than that at austre broggerbreen where subglacial drainage is absent and the yield is 0 48 kg naoh p km2 year therefore as since both detrimental and beneficial effects of sediment bound p loading in ice marginal receiving waters are possible i e either reduced primary productivity owing to increased turbidity or p fertilization following desorption there is a pressing need to assess the ambient p status of such environments and also the capacity for ice marginal ecosystems to adapt to such inputs copyright 2004 john wiley sons ltd

changes in geometry and subglacial drainage of midre lovenbreen svalbard determined from digital elevation models digital elevation models dems of the bed and surface of the polythermal midre lovenbreen svalbard are used to identify changes in glacier geometry between 1977 and 1995 the calculated mean annual mass balance 0 61 m water equivalent w e a 1 is more negative than that derived from field measurements 0 35 m w e a 1 although the error associated with this value 0 7 m a 1 suggests that the difference may be accounted for by errors however similar discrepancies between dem based and field based measurements of mass balance have been reported elsewhere in svalbard although errors may be responsible patterns of surface elevation change may also be explained in terms of patterns of ablation accumulation and dynamics the theoretical structure of the subglacial drainage system is modelled using different assumptions about subglacial water pressure in 1977 and 1995 these reconstructions are compared with the observed positions of proglacial outlet streams decreasing subglacial water pressure results in a decrease in the influence of surface morphology and an increase in the role of the bed topography on drainage routing which generally leads to more dispersed drainage long term changes in the position of proglacial outlet streams occur as a result of changes in glacier geometry but short term changes may also occur in response to early season water pressures controlled by meteorological and hydrological conditions copyright 2003 john wiley sons ltd

tsunami forecast analysis for the may 2006 tonga tsunami 1 this study applies tsunami forecast models developed for noaa s tsunami warning and forecast system to investigate the may 2006 tonga tsunami inversion of the deep ocean assessment and reporting of tsunamis dart measurements estimates a tsunami magnitude equivalent to an earthquake moment magnitude of 8 0 the dart constrained modeling forecasts show good agreement with observations at eight coastal tide stations in hawaii u s west coast and alaska including first arrival times wave periods wave amplitudes and decay during the day following the earthquake the forecast system correctly reproduces the reflected waves from north america and the scattered waves by the bottom topography in the south pacific which arrived in the hawaiian islands 16 and 18 5 h after the earthquake respectively wavelet analysis of the tsunami waves suggests that harbor and local shelf resonances may be predominantly responsible for the late occurrence of the maximum wave observed in some coastal areas these results suggest expanding the operational use of the real time forecast models and demonstrate the applicability of the forecast results for all clear evaluations search and rescue operations as well as event and postevent planning this research highlights the value of high resolution inundation models in real time forecasts during a long duration hazard for coastal communities it also provides a rigorous and successful test of the performance and accuracy of the forecast models when run in real time mode

spectral analysis of tsunami waves separation of source and topography effects a new approach is proposed to separate the influence of source and topography in observed tsunami spectra and to reconstruct the initial source spectrum the method assumes a linear tide gauge response to external forcing and is based on comparative analysis of tsunami and background spectra evaluation of the ratio of tsunami to background spectra gives functional characteristics that are invariant of station location and dependent only on the source parameters three events the urup tsunami of december 22 1991 northwest pacific the hokkaido southwest okushiri tsunami of july 12 1993 sea of japan and the shikotan tsunami of october 4 1994 northwest pacific are used as examples of the proposed approach the source spectra reconstructed from the analysis of different tide gauges were found to be in good agreement with each other and with the seismological geodetic and field survey data

rapid fluvial incision and headward erosion by the yellow river along the jinshaan gorge during the past 1 2 ma as a result of tectonic extension abstract in north china the ordos block located northeast of the tibetan plateau is regarded as a stable craton surrounded by the yinchuan graben to the west the hetao graben to the north and the fenwei graben to the southeast the major tectonic structure around this block in the cenozoic reflects intensive extension as a response to the eastward extrusion of the tibetan plateau intermittent downcutting by the yellow river starting from the planation surface level on the ordos block and penetrating the bedrock resulted in the formation of the jinshaan gorge a series of well preserved fluvial terraces was identified along this gorge providing new insight into the far field effect of the eastward extrusion of the tibetan plateau magnetostratigraphic records from the planation surface and uppermost terrace suggest that this gorge has been entrenched over its total length in the period from 3 7 to 1 2 ma a preliminary explanation is proposed here for the morphological evolution of the yellow river in the jinshaan gorge on the basis of terrace correlation between seventeen geomorphic sections multiwave headward erosion initiated by the yellow river along this gorge has been reconstructed this process may be attributed to the lowering of the base level the fenwei graben this graben has been formed during the cenozoic as the tibetan plateau extruded eastwards resulting in accelerated ground subsidence a combined approach of magnetostratigraphy pedostratigraphy and optically stimulated luminescence osl was adopted to establish a new geochronology for terraces in the gorge at 1 2 ma 1 1 ma 787 ka 412 ka 245 ka 128 ka 29 ka and 11 ka these ages provide an excellent framework for calculating the extension within the fenwei graben the average incision rate appears to be enhanced significantly since 412 ka indicating a rapid extension within the fenwei graben during this time

magnetostratigraphic dating of river terraces rapid and intermittent incision by the yellow river of the northeastern margin of the tibetan plateau during the quaternary up to 23 paleosols have been identified in loess sequences that overlie fluviatile sediments on seven terraces of huang he the yellow river and daxia he in the linxia basin at the northeastern margin of the tibetan plateau the magnetostratigraphic record in the oldest sequence appears to be fairly complete and spans the entire quaternary it includes evidence for the jaramillo and olduvai normal polarity subchrons within the matuyama chron as well as the cobb mountain and stage 54 formerly gilsa events age constraints within the brunhes are provided by 14c and thermoluminescence optical stimulated luminescence dating the magnetostratigraphic chronology of the quaternary sediments indicates that terraces were formed at about 1 66 1 4 1 1 0 6 0 12 0 055 and 0 01 ma the terraces may represent climatically induced pauses in long term tectonically induced incision by the rivers on the basis of terrace heights and ages incision rates were highest from 1 66 to 1 4 ma 1 m kyr decreased from 1 4 to 0 12 ma 0 1 m kyr and increased from 0 12 ma to present 0 75 m kyr if river incision is attributed solely to uplift of the tibetan plateau then this uplift appears to have been rapid as well as intermittent following the first evidence of the existence of huang he in this area at about 1 75 ma however the effects of uplift cannot be fully separated from incision caused by changes in climate copyright 1997 by the american geophysical union

stream response to quaternary tectonic and climatic change evidence from the upper weihe river central china abstract seven terraces of upper weihe river in the longxi basin on the north flank of the qinling mountains are capped with a succession of loess units and paleosols that correlate with the standard marine isotope chronology based on fieldwork and terrace ages which were determined using loess paleosol stratigraphy paleomagnetic optical stimulated luminescence osl and radiocarbon dating the results show that the fluvial fills were deposited during marine oxygen isotope stages miss 22 20 18 16 12 6 4 and 2 respectively whereas terracing occurred during glacial interglacial transitions this in turn points to eccentricity related climatic changes that may have driven recurrent incision and aggradation processes and significantly influenced the formation of staircase terraces of weihe river through the direct and indirect influence of both temperature and precipitation on fluviatile activity on the basis of terrace ages and its heights incision rates were enhanced from 865 to 412 ka 0 27 m ka decreased from 412 to 128 ka 0 09 m ka and increased from 128 ka to present 0 32 m ka

multi year water and surface energy budget of a high latitude polythermal glacier evidence for overwinter water storage in a dynamic subglacial reservoir this paper examines the water budget and surface energy balance of a svalbard glacier midre lovenbreen over a 6 year period 1997 2002 fresh water yields are found to lie between 1 1 and 1 5 m a 1 and reflect variable amounts of glacier ice ablation 0 27 0 15 m a 1 and more consistent amounts of snowmelt and summer precipitation 0 40 0 10 and 0 49 0 12 m respectively between 24 and 36 of the annual runoff is thought to pass through a subglacial drainage system although the site is heavily influenced by stable maritime air masses during the summer surface melting is achieved largely by net shortwave radiation fluxes 74 100 of ablation water budget analysis shows that the annual runoff yields may be strongly influenced by water storage within the glacial system storage can occur over the winter period and force the early development of the subglacial drainage system during the following summer thus annual water fluxes from this glacier cannot be estimated from glacial mass balance data alone and there is a need to assess the implications of overwinter storage for our understanding of glacial dynamics annual fluvial process rates and mixing processes in svalbard s fjords

the hydrochemistry of meltwaters draining a polythermal based high arctic glacier south svalbard i the ablation season solute and runoff time series at finsterwalderbreen svalbard provide evidence for considerable basal routing of water and the existence of at least two contrasting subglacial chemical weathering environments the hydrochemistry of a subglacial upwelling provides evidence for a snowmelt fed subglacial reservoir that dominates bulk runoff during recession flow high concentrations of cl and crustal ions high pco2 and ratios of so2 4 so2 4 hco 3 close to 0 5 indicate the passage of snowmelt through a subglacial weathering environment characterized by high rock water ratios prolonged residence times and restricted access to the atmosphere at higher discharges bulk runoff becomes dominated by icemelt from the lower part of the glacier that is conveyed through a chemical weathering environment characterized by low rock water ratios short residence times and free contact with atmospheric gases these observations suggest that icemelt is routed via a hydrological system composed of basal ice marginal englacial and supraglacial components and is directed to the glacier margins by the ice surface slope upwelling water flows relatively independently of icemelt to the terminus via a subglacial drainage system possibly constituting flow through a sediment layer cold basal ice at the terminus forces it to take a subterranean routing in its latter stages the existence of spatially discrete flow paths conveying icemelt and subglacial snowmelt to the terminus may be the norm for polythermal based glaciers on svalbard proglacial mixing of these components to form the bulk meltwaters gives rise to hydrochemical trends that resemble those of warm based glaciers these hydrochemical characteristics of bulk runoff have not been documented on any other glacier on svalbard to date and have significance for understanding interactions between thermal regime and glacier hydrology 1998 john wiley sons ltd

pedogenic response to millennial summer monsoon enhancements on the tibetan plateau abstract the asian summer monsoons experienced both rapid episodic enhancement and long term evolution with the uplift of tibet the response of pedogenesis to those events on the tibetan plateau at mean elevations of 4000 5000 m is of great interest and significance in deciphering the history of asian and tibetan summer monsoons and in understanding soil development deterioration and management the over 22 m loess paleosol sequence at hezuo on the eastern tibetan plateau extending back through the last interglaciation and the thickest late pleistocene sequence identified thus far on the plateau provides a unique opportunity to tackle the above topics detailed chronology and soil development determined by field pedofeatures and soil proxies have revealed a millennial fluctuation of the asian and tibetan summer monsoons resembling the late pleistocene north atlantic climatic record the end of each heinrich event is closely followed by formation of a stronger paleosol and then some much weaker thin soil horizons weathered loess or loess the episodes of stronger soil development or paleosol events correspond without exception to strongest summer monsoon enhancement at the beginning or in the early part of each bond cycle recorded in the north atlantic the strongest pedogenesis and summer monsoon enhancement is observed to occur during 43 36 ka bp which is not observed in climatic records outside tibet probably indicating a coherent enhancement of asian and tibetan summer monsoons in the last mega interstadial mis3 increase of organic matter excluding decomposition and change of soil types from last interglacial calcic cambisols to holocene chernozems suggests an increase of relative humidity implying partially an increase of elevation due to late pleistocene rapid uplift of the tibetan plateau

kuril islands tsunami of november 2006 1 impact at crescent city by distant scattering 1 a numerical model for the global tsunami computation constructed by kowalik et al 2005 2007a is applied to the tsunami of november 15 2006 in the northern pacific with spatial resolution of one minute numerical results are compared to sea level data collected by pacific dart buoys the tide gauge at crescent city cc recorded an initial tsunami wave of about 20 cm amplitude and a second larger energy packet arriving 2 hours later the first energy input into the cc harbor was the primary direct wave traveling over the deep waters of the north pacific interactions with submarine ridges and numerous seamounts located in the tsunami path were a larger source of tsunami energy than the direct wave travel time for these amplified energy fluxes is longer than for the direct wave prime sources for the larger fluxes at cc are interactions with koko guyot and hess rise tsunami waves travel next over the mendocino escarpment where the tsunami energy flux is concentrated owing to refraction and directed toward cc local tsunami amplification over the shelf break and shelf are important as well in many locations along the north pacific coast the first arriving signal or forerunner has lower amplitude than the main signal which often is delayed understanding this temporal distribution is important for an application to tsunami warning and prediction as a tsunami hazard mitigation tool we propose that along with the sea level records which are often quite noisy an energy flux for prediction of the delayed tsunami signals be used

temporal variations in flow velocity at finsterwalderbreen a svalbard surge type glacier inter and intra annual velocity variations are well known on alpine glaciers but their importance for arctic glaciers has only been recognized more recently this paper presents flow velocity data from finsterwalderbreen a 35 km 2 polythermal surge type glacier in southern svalbard that is presently 100 years into its quiescent phase field measurements of glacier surface velocities are available from 1950 52 and 1994 97 and mean velocities for the last decade are estimated for the lower glacier using cables drilled to the glacier bed these velocities show substantial seasonal variations indicating that basal sliding is an important component of surface velocities and interannual fluctuations of up to 75 possibly indicating variations in subglacial water storage several lines of evidence indicate that this glacier has an extensive subglacial hydrological system generally considered to be a prerequisite for surge type glaciers which is at least partly pressurized information on surface morphology from 1898 onwards shows that the glacier has experienced continuous retreat since the last surge in about 1910 and has now retreated 1 5 km further back than its previous pre surge position in 1898 tracking of moraine loops on terrestrial and aerial photographs acquired over a 100 year period indicates that the surge period of finsterwalderbreen may be lengthening in response to climate changes

stable isotope evidence for microbial sulphate reduction at the bed of a polythermal high arctic glacier glacier beds may be host to a range of microbial communities which drive oxic waters towards anoxia along certain hydrological flowpaths chemical and isotopic signatures in meltwaters from finsterwalderbreen a polythermal glacier on sedimentary bedrock in svalbard show clear evidence for anoxia at the glacier bed increases in 34s and 18o of sulphate indicate that microbial sulphate reduction has resulted in significant decreases in sulphate concentration the 13c of the dissolved inorganic carbon dic is isotopically light 13c 8 which is consistent with the use of bedrock kerogen and or the necromass of sulphide oxidising bacteria as organic substrates for the sulphate reducing bacteria calculated rates of organic carbon mineralisation correspond to 10 of the total annual dic flux of the glacial meltwaters this microbial ecosystem is chemoautotrophically based ultimately being sustained by the kerogen and or bacterial necromass and sulphides in the bedrock this work suggests that glacier beds can be refugia for life when climatic and or atmospheric conditions are otherwise inclement and also supports the contention that microbial life is present in subglacial lake vostok

currents drag and sediment transport induced by a tsunami 1 we report observations of water surface elevation currents and suspended sediment concentration ssc from a 10 m deep site on the inner shelf in northern monterey bay during the arrival of the 2010 chile tsunami velocity profiles were measured from 3 5 m above the bed mab to the surface at 2 min intervals and from 0 1 to 0 7 mab at 1 hz ssc was determined from the acoustic backscatter of the near bed profiler the initial tsunami waves were directed cross shore and had a period of approximately 16 min maximum wave height was 1 1 m and maximum current speed was 0 36 m s during the strongest onrush near bed velocities were clearly influenced by friction and a logarithmic boundary layer developed extending more than 0 3 mab we estimated friction velocity and bed shear stress from the logarithmic profiles the logarithmic structure indicates that the flow can be characterized as quasi steady at these times at other phases of the tsunami waves the magnitude of the acceleration term was significant in the near bed momentum equation indicating unsteady flow the maximum tsunami induced bed shear stress 0 4 n m2 exceeded the critical shear stress for the medium grained sand on the seafloor cross shore sediment flux was enhanced by the tsunami oscillations of water surface elevation and currents continued for several days the oscillations were dominated by resonant frequencies the most energetic of which was the fundamental longitudinal frequency of monterey bay the maximum current speed hourly timescale in 18 months of observations occurred four hours after the tsunami arrived

adcp observations of edge waves off oahu in the wake of the november 2006 kuril islands tsunami received 13 september 2007 revised 5 october 2007 accepted 8 november 2007 published 15 december 2007 1 during the 2006 kuril islands tsunami edge waves propagating along oahu s south shore were observed via depth averaged adcp velocity and pressure data acquired in real time by a coastal observatory at 12 m depth and 400 m offshore time varying rotary component velocity spectra obtained via wavelet analysis agree with the phase lag observed between pressure and each cartesian velocity component in indicating the directions of rotation and travel of progressive edge waves furthermore the theoretical ratios between power in the free surface elevation and in each velocity component of edge waves agree with those observed and a nonlinear shallow water model shows edge waves of various modes propagating along the shore near our observation location importantly the maximum surge in sea level occurred at a time when edge waves of all constituent frequencies were superposed citation bricker j d s munger c pequignet j r wells g pawlak and k f cheung 2007 adcp observations of edge waves off oahu in the wake of the november 2006 kuril islands tsunami geophys res lett 34 l23617 doi 10 1029 2007gl032015

distribution of ammonium in minerals of metamorphic and granitic rocks abstract sixty nine analyses are given for nh4 in minerals of metamorphic and granitic rocks mostly from the ryoke belt japan the distribution of nh4 in coexisting minerals is quite systematic suggesting that nh4 is one of the stable geochemical components in high temperature processes biotite has the highest content of nh4 followed by muscovite k feldspar and plagioclase pure quartz is almost free from nh4 calcic plagioclase contains less nh4 than does sodic plagioclase the partition coefficients d pl bi d kf bi and d kf bi are on the average 0 11 0 38 and 0 43 respectively the fractionation of nh4 in these minerals is quite similar to that of rb but much smaller than that of cs distribution of nh4 as well as those of rb and cs appears to be explained by its ionic radius and the shortest cation o distances in alkali positions of minerals

pedosedimentary development and palaeoenvironmental significance of the s1 palaeosol on the northeastern margin of the qinghai xizang tibetan plateau the s1 pedocomplex correlated to oxygen isotope stage 5 of the ocean cores has been traced west of the loess plateau on to the extreme northeastern margin of the qinghai xizang tibetan plateau in china detailed micromorphological analysis of closely spaced thinsections from the pedocomplex at this site provides the basis for reconstruction of the sequence of pedosedimentary processes and associated palaeoenvironmental changes occurring during this time interval the six pedosedimentary stages identified are interpreted in terms of temporal variations in depositional rates size of particles transported and availability of moisture for pedogenic alteration as determined by changing balances in dominance of winter and summer monsoonal forces two main soil forming intervals are identified the more extensive of the two in terms of resultant pedological features reflects pedogenic alteration at a relatively stable land surface under a semi arid climate during the later part of pedosedimentary stage 2 the other main period corresponds to pedosedimentary stages 4 and 5 when leaching and bioturbation processes were active at aggrading surfaces leading to development of an accretionary unit without clear differentiation of horizons pedosedimentary stages 1 3 and 6 were characterised mainly by rapid rates of coarse loess accumulation with synsedimentary modification restricted to surface slaking and crust formation and minor localised redistribution of calcite

spatial and temporal variations in surface velocity and basal drag across the tongue of the polythermal glacier midre lovenbreen svalbard we present results of a detailed investigation of surface motion across the tongue of a polythermal glacier midre lovenbreen svalbard during the 1999 summer surface velocities in the warm based upper tongue increased during periods of enhanced surface melting and rainfall events and force balance analysis indicates that these velocity variations were locally forced probably by fluctuations in subglacial water pressure surface speed ups were also observed on the cold based lower tongue which acted as a sticky spot through which there was minimal subglacial drainage for most of the summer but these were largely non locally forced by longitudinal coupling to the faster moving ice up glacier on one occasion however a large rapid input of surface water to the glacier reduced the basal drag beneath the cold based lower tongue presumably due to hydraulic jacking this resulted in locally forced enhanced surface velocities across the entire tongue accompanied by a breaching of the lower tongue and an outburst of subglacially stored water

magnetic grain size distribution of the enhanced component in the loess palaeosol sequences in the western loess plateau of china summary rock magnetic measurements of chinese loess palaeosol samples from the beiyuan section in linxia city suggest the presence of two magnetic components a background component and an enhanced component the magnetic properties of the enhanced component suggest strong grain size control which is in contrast with variable grain size distribution in loess palaeosol from the central loess plateau chemically formed magnetic grains do not fulfil the requirements in the case of the western loess plateau because they may show shifts in the grain size distribution the difference in climate between the western and central loess plateau may lead to different origins and different preservation conditions of the pedogenic magnetite

reinterpreting climate proxy records from late quaternary chinese loess a detailed osl investigation abstract numerous authors have utilised physical properties of chinese loess and red clay deposits to develop apparently detailed and continuous past climate records from the miocene into the holocene many of these studies have further suggested that the principal climatic agent responsible for the aeolian emplacement and diagenesis of chinese loess the east asian monsoon has fluctuated rapidly on millennial to sub millennial timescales in concert with dramatic changes in the north atlantic dansgaard oeschger cycles and heinrich events and the western pacific el nino southern oscillation much of this evidence is based on reconstructions and age models that are tied to assumptions concerning the nature of loess sedimentation and diagenesis for example the belief that loess sedimentation can be viewed as essentially continuous some authors have however cast doubt on these assumptions and suggest that the application of radiometric techniques may be required to determine their validity recent studies utilising optically stimulated luminescence osl methods have reinforced these doubts and here osl dates obtained at 10 cm intervals from three sites along a transect across the chinese loess plateau have been used in combination with climate proxy evidence to test the existing assumptions that underpin many palaeoclimatic reconstructions from loess in this way the first time continuous and independently dated late quaternary climate reconstruction is developed from loess the data indicate that sedimentation is episodic and that once emplaced loess is prone to pedogenic disturbance diagenetic modification and in some cases erosion the relationships between proxies and sedimentation rates are also assessed and climatic interpretations based on different age models compared the implications of these findings for reconstructions of climate from loess are explored and comparisons are made between the developed palaeoclimate records and evidence from ice and ocean cores this exercise also highlights important information concerning the relative influence of forcing mechanisms behind east asian monsoon change over the late quaternary

isotopic variations of the fixed nitrogen in metamorphic rocks the content and isotopic composition of fixed nitrogen nh 4 n in metasedimentary rocks phyllites mica schists and gneisses from prograde metamorphic zones in the erzgebirge saxon ore mountains g d r were measured and show that the nitrogen content decreases and 15n increases with increasing metamorphic grade the geochemical and isotopic behaviour of nitrogen during contact metamorphism was investigated in a mica schist profile through the contact aureole of a granitic pluton the nitrogen concentrations of the wall rocks decrease towards the contact whereas the 15n values become higher various model experiments were carried out in the laboratory to explain the changes observed in the rock samples the nitrogen isotope fractionation factor was determined for the isotopic exchange in the system ammonium sulphate ammonia at 250 c 1 0143 0 0012 and 350 c 1 0128 0 0006 in accordance with the model experiments the conclusion seems warranted that the change in nitrogen content and its isotopic composition in rocks during metamorphic processes depend mainly on the metamorphic temperature

last glacial climate instability documented by coarse grained sediments within the loess sequence at fanjiaping lanzhou china optically stimulated luminescence dating grain size analysis and magnetic susceptibility measurements were conducted on the fanjiaping loess section from the western chinese loess plateau the results confirm that last glacial high frequency climatic shifts were documented in mid latitude continental archives the grain size record indicated that coarse grained sediments with horizontal bedding and channel fill structures were only deposited in several short intervals equivalent to the beginning of marine oxygen isotope stage mis 4 and the early to middle mis 3 this probably implies brief rainfall intensification of the asian summer monsoon and its disappearance since the late mis 3 to mis 2 may have been a response to significant glacial cooling in the northern hemisphere previous investigations revealed high sea surface temperatures at high latitudes at the start of mis 4 and the early to middle mis 3 intensification of summer insolation in the northern hemisphere implying evident climate amelioration climate improvement favors boreal forest recovery enhancing both winter and summer air temperatures the resultant smaller equator polar temperature gradient probably helped the moisture laden summer monsoon to penetrate northward this study thus provides new significant information about the response of terrestrial loessic palaeoenvironments to millennial timescale climatic fluctuations during the last glacial period

observed and modeled currents from the tohoku oki japan and other recent tsunamis in northern california we investigate the currents produced by recent tsunamis in humboldt bay and crescent city california the region is susceptible to both near field and far field tsunamis and has a historic record of damaging events crescent city harbor located approximately 100 kms north of humboldt bay suffered us 28 million in damages from strong currents produced by the 2006 kuril islands tsunami and an additional us 26 million from the 2011 japan tsunami in order to better evaluate these currents in northern california we deployed a nortek aquadopp 600 khz 2d acoustic doppler current profiler adcp with a 1 min sampling interval in humboldt bay near the existing national oceanic and atmospheric administration noaa national ocean service nos tide gauge station the instrument recorded the tsunamis produced by the mw 8 8 chile earthquake on february 27 2010 and the mw 9 0 japan earthquake on march 11 2011 one other tsunami was recorded on the humboldt bay tide gauge during the period of adcp operation but was not visible on the adcp suggesting a threshold water level value of about 0 2 m to produce an observable adcp record the 2010 tsunami currents persisted in humboldt bay for approximately 30 h with peak amplitudes of about 0 35 m s the 2011 tsunami signal lasted for over 40 h with peak amplitude of 0 84 m s the strongest currents corresponded to the maximum change in water level approximately 67 min after the initial wave arrival no damage was observed in humboldt bay for either event in crescent city currents for the first three and one half hours of the 2011 japan tsunami were estimated using security camera video footage from the harbor master approximately 70 m away from the noaa nos tide gauge station the largest amplitude tide gauge water level oscillations and most of the damage occurred within this time window the currents reached a velocity of approximately 4 5 m s and six cycles exceeded 3 m s during this period measured current velocities both in humboldt bay and in crescent city were compared to calculated velocities from the method of splitting tsunamis most numerical model the frequency and pattern of current amplification and decay at both locations are replicated by the most model for the first several hours after the tsunami onset most generally underestimates 2011 peak current velocities by about 10 30 with a few peaks by as much as 50 at humboldt bay most predicted attenuation of the signal after 4 h but the actual signal persisted at a nearly constant level for at least twice as long the results from this project demonstrate that adcps can effectively record tsunami currents for small to moderate events and can be used to calibrate and validate models i e most in order to better understand hazardous tsunami conditions within harbors

biopores and root features as new tools for improving paleoecological understanding of terrestrial sediment paleosol sequences abstract the important role of roots and rhizosphere processes is accepted for the top soil but still under debate for the deep subsoil including soil parent material especially for terrestrial sediments like loess and dune sands roots and root traces are mostly recognized in profile descriptions but not interpreted in the paleoenvironmental context further synchrony of sediment deposition and root trace formation is commonly assumed this is challenged by partially large maximum rooting depths of plants exceeding the soil depth and by frequent occurrence of secondary carbonates and biopores of potential root origin below recent soil and paleosols to improve understanding of paleoenvironmental records in terrestrial sediment paleosol sequences recent roots and root traces including calcified roots and root derived biopores were investigated in six soil loess and dune sand profiles across central and se europe visualization of small carbonate accumulations diameter 1 mm frequently called pseudomycelia by x ray microtomographic scanning and morphologic comparison with rhizoliths calcified roots diameter mostly 3 20 mm up to 100 mm possible indicate root origin of the former therefore requiring renaming to microrhizoliths quantification of roots biopores rhizoliths and microrhizoliths on horizontal levels yielded maximum frequencies of 2100 m 2 4100 m 2 196 m 2 and 12 800 m 2 respectively considering the pore volume remaining from former root growth this indicates their significant contribution to structural properties of the sediments and paleosols depth distribution of roots and root traces was frequently related to soil and paleosols respectively and mostly showed maximum frequencies within or immediately below these units root traces are therefore not necessarily of similar age like the surrounding sediment but are typically of younger age the time lag between root traces and the surrounding stratigraphic unit can vary between small time periods likely decades to centuries in case of microrhizoliths and several millenia in case of larger rhizoliths penetrating several stratigraphic units with assumed radii of former rhizosphere extension of 5 mm for microrhizoliths a frequency of 12 500 m 2 corresponded to 100 rhizosphere area in the respective depth interval these findings emphasize the meaning of root traces in sediment paleosol sequences potential temporal and spatial inhomogeneity of root growth on the one hand especially for shrub and tree vegetation and occurrence of root remains of different age and origin in identical depth intervals on the other hand hamper the assessment of the chronologic context of these with the surrounding sediment or paleosol nevertheless root traces in terrestrial archives provide valuable information with respect to paleovegetation and paleoenvironmental conditions if their chronological context is known

last glacial pollen record from lanzhou northwestern china and possible forcing mechanisms for the mis 3 climate change in middle to east asia abstract the vegetation on the northeastern margin of the tibetan plateau is highly sensitive to climatic changes and thus represents a potentially interesting environmental archive pollen samples from the fanjiaping loess section in lanzhou on the western chinese loess plateau clp were analyzed in conjunction with osl dating the results indicate that pollen zone b 60 6 46 0 ka correlative to the early mis 3 had the greatest abundances of cupressaceae tsuga gramineae and cyperaceae of the entire section suggesting a warm phase during the last glacial period these pollen taxa decreased significantly in abundance in the zones c 46 0 39 0 ka and d 39 0 27 0 ka reflecting a substantial climate cooling from the middle mis 3 to mis 2 these results correlate with climate records from the south china sea the clp baikal lake north america north atlantic ocean and other regions and probably correspond with the decline of northern high latitude insolation and the increase of global ice volume from 50 to 20 ka in particular arboreal pollen fern spore and algae abundances declined sharply since 40 ka while shrub and herb pollen reached the highest abundances conifer pollen picea and abies abundance also rose markedly and increased up the section this implies significant climate deterioration and likely corresponded with substantial growth of the polar ice sheets since 40 ka the decreasing temperature caused by an insolation decline during the last glacial period probably reinforced the cooling effect in a snow ice albedo feedback which would result in less climate sensitivity to radiative forcing meanwhile vegetation decline in the northern hemisphere during the last glacial period and tundra development at high latitudes possibly caused additional cooling enhancing the growth of polar ice sheets since 40 ka the development of polar ice sheets increased the polar to equator temperature and pressure gradients strengthening the westerlies and supplying plenty of moisture to northwest china during 40 30 ka lake sediments developed widely on the tibetan plateau during 40 30 ka probably related to an increase in the seasonality of middle to low latitude insolation which caused an enhancement of glacier melting on the plateau

optical characteristics of cryoconite surface dust on glaciers the relationship between light absorbency and the property of organic matter contained in the cryoconite

the role of fungal biomineralization in the formation of early carboniferous soil fabrics paleosols in the lower carboniferous limestones of south wales commonly contain needle fibre calcite which is an unusual form of calcite recently shown to form by the calcification of fungal hyphae in present day soils the needle fibre calcite occurs in two associations in the paleosols as coatings on sediment grains and as rhizocretions the former can be compared with the microbial grain coatings of quaternary calcretes the latter represent the sites of fungal coats on roots and are interpreted as probable ectomycorrhizae a symbiotic fungal sheath root association these findings suggest that biomineralization was important in the formation of soil fabrics during the carboniferous as it is in present day soils

edge wave and non trapped modes of the 25 april 1992 cape mendocino tsunami the 25 april 1992 cape mendocino earthquake generated a tsunami characterized by both coastal trapped edge wave and non trapped tsunami modes that propagated north and south along the u s west coast both observed and synthetic time series at crescent city and north spit are consistent with the zero order edge wave mode solution for a semi infinite sloping beach depth profile wave amplitudes at crescent city were about twice that observed at north spit in spite of the fact that the source region was three times farther from crescent city than north spit the largest observed amplitude was due to an edge wave which arrived almost three hours after the initial onset of the tsunami since such waves are highly localized nearshore this suggests that the enhanced responsiveness at crescent city is at least partly due to local dynamic processes furthermore the substantially delayed arrival of this wave which was generated at the southern end of the cascadia subduction zone has significant implications for hazard mitigation efforts along the entire u s west coast specifically this study demonstrates that slow moving but very energetic edge wave modes could be generated by future large tsunamigenic earthquakes in the csz and that these might arrive unexpectedly at coastal communities several hours after the initial tsunami waves have subsided

micromorphological fabrics and developmental stages of carbonate nodular forms related to soil characteristics abstract carbonate nodules often constitute the first stage of calcrete formation micromorphological analysis of carbonate nodules and nodular fabrics in different soil materials shows that their development is a function of several factors nature of the host matrix texture porosity carbonate and non carbonate clay distribution bulk density and the interactions among them different micromorphological stages therefore exist in different soil materials in calcareous medium textured soil materials the stages of nodule formation are related to the increase of the density of the nodule caused by the accumulation of microcalcites in such a soil material the following stages occur 1 microcalcites within the low to moderate density matrix 2 microcalcites of moderate to high density and moderately dense diffuse nodules parallel calcans may occur 3 microcalcites of high density with dense microcalcitic nodules during these stages the amount of non carbonate clay decreases but is homogeneously dispersed and disseminated with the microcalcites in general the size of microcalcites 1 8 m is inversely related to the clay content in non calcareous medium to fine textured soil materials secondary carbonate precipitates in intrapedal and or interpedal voids as large sparry crystals due to pedoturbation processes the nodules thus formed are subjected to recrystallization resulting in a microsparry pattern the development stages are 1 few calcans and crystal chambers 2 crystic nodules mainly of sparry crystals and an increase of calcans and crystic chambers 3 recrystallized nodules composed mainly of microspars in coarse grained materials secondary carbonates precipitate directly in voids as sparry crystals and the resulting nodules are of the crystic type the large crystals are often subjected to recrystallization in partly calcareous coarse grained materials with additions of calcareous dust particular micromorphological carbonate forms occur in the c horizon cutanic calciasepic fabric forms besides zones of crystic fabric which gradually become calciasepic in the b horizon and include the typical nodular forms of the calcareous medium textured soil material together with appreciable amounts of glaebular halos the processes leading to the formation of these stages occur essentially without a significant biogenic influence where carbonate segregation occurs as rhizomorphs surrounding active roots the fabric is always micritic even in coarse textural soil material

loess stratigraphy in central china abstract the loess deposits in central china record world wide climate changes of the last 2 5 ma numerous climatic oscillations are marked by alternating loess and soil units with continuous coverage of the matuyama and brunhes epochs magnetic susceptibility of the deposits correlates closely with the oxygen isotope record of the deep sea sediments and provides an independent measure of climate and time the key marker bed of the chinese loess sequence is the paleosol s5 the time equivalent of the mid brunhes oxygen isotope stages 13 14 and 15 it marks a prolonged interval of warm humid climate lasting from approximately 615 to 470 thousand years ago several episodes of river downcutting coincide with deposition of the exceptionally thick loess units l1 oceanic oxygen isotope stages 2 to 4 l2 stage 6 l5 stage 12 l6 stage 16 l9 stage 22 l15 stage 38 about 1 15 ma and ws4 about 2 3 ma these erosional events are interpreted as a result of episodic uplift of the loess plateau the deposition of the earliest loess layers between 2 5 and 2 3 ma ago marks a first order shift from warm and humid environments toward harsh continental steppes comparable to those of the middle and late pleistocene little if any lithologic or paleontologic changes were noted within or above the olduvai magnetozone so that the proposed plio pleistocene boundary at approximately 1 65 ma has no lithostratigraphic and biostratigraphic representation in the chinese loess series comparison with the deep sea drilling program core 552a in the north atlantic and with the santerno river section near bologna shows that the occurrence of the earliest loess in china coincides with the timing of the first significant ice rafting in the north atlantic and with the appearance of cold water foraminifers in the marine deposits of northern italy an extension of the stage system of the oxygen isotope signal extended back to the gauss matuyama boundary is proposed

geochemical weathering at the bed of haut glacier d arolla switzerland a new model waters were sampled from 17 boreholes at haut glacier d arolla during the 1993 and 1994 ablation seasons three types of concentrated subglacial water were identified based on the relative proportions of ca 2c h co 3 and so4 2 to si type a waters are the most solute rich and have the lowest relative proportion of si they are believed to form in hydrologically inefficient areas of a distributed drainage system most solute is obtained from coupled sulphide oxidation and carbonate dissolution so cd it is possible that there is a subglacial source of o2 perhaps from gas bubbles released during regelation because the high so4 2 levels found up to 1200 eq l are greater than could be achieved if sulphides are oxidized by oxygen in saturated water at 0 c c 414 eq l a more likely alternative is that sulphide is oxidized by fe 3c in anoxic environments if this is the case exchange reactions involving fe iii and fe ii from silicates are possible these have the potential to generate relatively high concentrations of hco3 with respect to so4 2 formation of secondary weathering products such as clays may explain the low si concentrations of type a waters type b waters were the most frequently sampled subglacial water they are believed to be representative of waters flowing in more efficient parts of a distributed drainage system residence time and reaction kinetics help determine the solute composition of these waters the initial water rock reactions are carbonate and silicate hydrolysis and there is exchange of divalent cations from solution for monovalent cations held on surface exchange sites hydrolysis is followed by so cd the so4 2 concentrations usually are 414 eq l although some range up to 580 eq l which suggests that elements of the distributed drainage system may become anoxic type c waters were the most dilute yet they were very turbid their chemical composition is characterized by low so4 2 h co3 ratios and high ph type c waters were usually artefacts of the borehole chemical weathering environment true type c waters are believed to flow through sulphide poor basal debris particularly in the channel marginal zone the composition of bulk runoff was most similar to diluted type b waters at high discharge and was similar to a mixture of type b and c waters at lower discharge these observations suggest that some supraglacial meltwaters input to the bed are stored temporarily in the channel marginal zone during rising discharge and are released during declining flow little of the subglacial chemical weathering we infer is associated with the sequestration of atmospheric co2 t he progression of reactions is from carbonate and silicate hydrolysis through sulphide oxidation by first oxygen and then fe iii which drives further carbonate and silicate weathering a crude estimate of the ratio of carbonate to silicate weathering following hydrolysis is 4 1 we speculate that microbial oxidation of organic carbon also may occur both sulphide oxidation and microbial oxidation of organic carbon are likely to drive the bed towards suboxic conditions hence we believe that subglacial chemical weathering does not sequester significant quantities of atmospheric co2 and that one of the key controls on the rate and magnitude of solute acquisition is microbial activity which catalyses the reduction of fe iii and the oxidation of fes2 copyright 2002 john wiley sons ltd

energy transfer between wind waves and low frequency oscillations on a fringing reef ipan guam field observations from a guam fringing reef are used to examine the cross reef energy exchange between high frequency sea and swell ss and low frequency infragravity ig and far infragravity fig waves energetic ss waves significant wave heights 2 4 m break at the outer reef leading to weak 1 m conditions on the shallow reef flat as ss waves shoal on the reef face before breaking ig and fig energy fluxes both increase through nonlinear energy transfer from the ss waves in contrast through the surf zone the ig energy flux decreases whereas fig flux increases the decrease in ig energy flux through the surf zone is attributed to breaking ss waves working against the incident bound ig wave energy which dominates breakpoint forced ig waves yielding a net flux decrease in contrast fig energy flux increases through the surf zone consistent with breakpoint forcing and the absence of an energetic bound fig component on the reef face ig and fig energy fluxes decay on the shallow reef flat due primarily to frictional dissipation with tidal modulations attributed to nonlinear conversion and friction forcing at fig frequencies may lead to a normal mode response on the reef with comparable incoming and outgoing fig energy fluxes at the outer reef flat depending on water level over the reef flat and the degree of frictional dissipation

coastal transition zone off chile 1 seven years of subsurface current observations at deep sea and continental slope moorings off chile 30 s satellite sea surface anomaly and satellite wind stress are used to examine space time and propagation characteristics of the mesoscale eddy activity in the coastal transition zone off chile this zone off chile extends from the coast to 600 800 km offshore and can be separated into two latitudinal regions the first region between 29 and 39 s off central chile is characterized by high eddy kinetic energy and strong but variable equatorward wind stress the second region between 19 and 29 s off northern chile is characterized by low eddy kinetic energy and weak but persistent equatorward wind stress low frequency mesoscale variability off central chile is mainly associated with baroclinic instability of coastal currents and westward propagation of rossby waves from the eastern boundary and is strongly modulated over el nino la nina cycles application of a new rotary wavelet spectrum method to the recording current meter data and the use of current estimates from satellite altimeter data show that mesoscale eddies and meanders in the coastal transition zone fluctuate with periods centered on 120 days and with length scales centered on 200 km cross rotary wavelet analyses of currents and wind stress indicate that fluctuations of coastal currents with periods longer than 220 days propagated westward as free rossby waves during 1995 1996 and as forced rossby waves during 1999 2001

fluvial terrace formation in the eastern fenwei basin china during the past 1 2 ma as a combined archive of tectonics and climate change abstract the key to understanding the fluvial response to climate change and surface uplift is a thorough distinguishing between their roles in terrace formation previous studies have tended to attribute the fluvial behavior of deposit incision alternation to climate cyclicity a preliminary explanation is proposed here for terrace formation in the eastern part of the fenwei basin china the observed fluvial terrace sequence was developed by the yellow river deeply downcutting into the emei platform which was uplifted within the eastern fenwei basin and therefore it probably records the tectonic history of this platform on the basis of the magnetostratigraphy and optically stimulated luminescence osl dating a ca 1 2 ma chronology was established for this terrace sequence pedostratigraphic analysis of the loess deposits accumulated on each tread reveals that the terrace deposits are overlain immediately by a paleosol bed suggesting that the abandonment of these terraces due to fluvial incision occurred at the transitions from glacial to interglacial climates the glacial interglacial climate cycle probably has a temporal control on the fluvial behavior of deposit incision alternation even though the yellow river develops in the subsiding fenwei basin the terrace generation may be sporadic and in the form of unusual stacked pattern before the emei platform was uplifted within the eastern fenwei basin the terrace staircases however formed in synchrony with glacial interglacial climate cycles since this platform began to uplift in the late middle pleistocene this result indicates that uplift may be necessary in large terrace staircase genesis it can force the river system to downcut deeply enough during climatic transitions to separate terrace levels adequately favoring the generation and subsequent preservation of the terrace treads the terrace sequence of the yellow river in the eastern fenwei basin therefore can be considered as a combined archive of climate change and local tectonic activity

ammonium concentration and nitrogen isotope composition in metasedimentary rocks from different tectonometamorphic units of the european variscan belt the content and isotopic composition of ammonium nh4 were measured by using kjeldahl distillation for 63 samples of predominantly metasedimentary rocks from two different geological settings of the european variscides i e the erzgebirge and the zone of erbendorf vohenstrauss in germany the studied erzgebirge schists represent an early paleozoic passive margin sequence that reappears in different deep subducted metamorphic units this allows an efficient examination of nitrogen loss and isotope fractionation during prograde metamorphism ammonium is found to be progressively depleted accompanied by a shift in 15n from the low grade units 2 kbar 300 c with 638 124 ppm and 15n 2 2 0 6 to the garnet phyllite unit 9 kbar 470 c with 621 190 ppm and 15n 3 5 0 9 the mica schist eclogite unit 12 kbar 550 c with 394 113 ppm and 15n 3 9 0 8 and to the gneiss eclogite unit 12 kbar 730 c with 99 32 ppm and 15n 7 7 2 0 using equilibrium models for rayleigh distillation and batch volatilization suggest that the nitrogen depletion took place by ammonia release only for the mica schists this isotope fractionation can be explained by the loss of molecular nitrogen in comparison with the early paleozoic schists the proterozoic ortho and paragneisses of the erzgebirge gneiss unit 6 8 kbar 650 c contain significantly lower amounts of ammonium 70 ppm and reach relatively low 15n values 2 5 to 3 6 the paragneisses from the zone of erbendorf vohenstrauss zev sampled from the ktb pilot hole represents a separate tectonometamorphic unit that has undergone polyphase metamorphic conditions with the major imprint being amphibolite facies 7 kbar 650 700 c the metagraywackes have nh4 contents of 80 ppm and 15n of approximately 6 gneisses in the vicinity of a late cataclastic shear zone at 2000 m depth are characterized by a shift in nh4 250 ppm and 15n up to 12 which suggest late fluid rock interactions with a nitrogen and 15n enriched fluid

tsunami trapping near circular islands trapping of long water waves that are induced by submarine earthquakes and that attack circular islands is studied by applying a theoretical model tinti andvannini 1994 that is based on the linear shallow water approximation the solution is computed as the superposition of the eigenmodes of the water basin the tsunami trapping is seen in terms of the capability of the source to excite the trapped eigenmodes of the basin the bottom depth dependence around the island is shown to be quite important in determining the trapping capability of the island a depth profile that is downwardly concave as the distance from the island coasts increases is substantially more efficient in amplifying the incoming waves and in trapping their energy than a profile exhibiting an upward concavity

widespread bacterial populations at glacier beds and their relationship to rock weathering and carbon cycling bacterial populations found in subglacial meltwaters and basal ice are comparable to those in the active layer of permafrost and orders of magnitude larger than those found in ice cores from large ice sheets populations increase with sediment concentration and 5 24 of the bacteria are dividing or have just divided suggesting that the populations are active these findings 1 support inferences from recent studies of basal ice and meltwater chemistry that microbially mediated redox reactions may be important at glacier beds 2 challenge the view that chemical weathering in glacial environments arises from purely inorganic reactions and 3 raise the possibilities that redox reactions are a major source of protons consumed in subglacial weathering and that these reactions may be the dominant proton source beneath ice sheets where meltwaters are isolated from an atmospheric source of co 2 microbial mediation may increase the rate of sulfide oxidation under subglacial conditions a suggestion supported by the results of simple weathering experiments if subglacial bacterial populations can oxidize and ferment organic carbon it is important to reconsider the fate of soil organic carbon accumulated under interglacial conditions in areas subsequently overridden by pleistocene ice sheets

vostok ice core a continuous isotope temperature record over the last climatic cycle 160 000 years a continuous deuterium profile along the 160 000 year vostok ice core antarctica is interpreted in terms of atmospheric temperature changes this climatic record is the awaited terrestrial complement of the deep sea records supporting the existence of a relation between the pleistocene climate and orbital forcing

variability in the chemical composition of in situ subglacial meltwaters meltwaters collected from boreholes drilled to the base of the haut glacier d arolla switzerland have chemical compositions that can be classified into three main groups the first group is dilute whereas the second group is similar to though generally less concentrated in major ions than contemporaneous bulk glacial runoff the third group is more concentrated than any observed bulk runoff including periods of flow recession waters of the first group are believed to represent supraglacial meltwater and ice melted during drilling limited solutes may be derived from interactions with debris in the borehole the spatial pattern of borehole water levels and borehole water column stratification combined with the chemical composition of the different groups suggest that the second group represent samples of subglacial waters that exchange with channel water on a diurnal basis and that the third group represent samples of water draining through a distributed subglacial hydraulic system high no 3 concentrations in the third group suggest that snowmelt may provide a significant proportion of the waters and that the residence time of the waters at the bed in this particular section of the distributed system is of the order of a few months the high no 3 concentrations also suggest that some snowmelt is routed along different subglacial flowpaths to those used by icemelt the average so2 4 hco 3 so2 4 ratio of the third group of meltwaters is 0 3 suggesting that sulphide oxidation and carbonate dissolution which gives rise to a ratio of 0 5 cannot provide all the hco 3 to solution hence carbonate hydrolysis may be occurring before sulphide oxidation or there may be subglacial sources of co2 perhaps arising from microbial oxidation of organic c in bedrock air bubbles in glacier ice or pockets of air trapped in subglacial cavities the channel marginal zone is identified as an area that may influence the composition of bulk meltwater during periods of recession flow and low diurnal discharge regimes 1997 by john wiley sons ltd

palaeomonsoon variability in the southern fringe of the badain jaran desert china since 130 ka bp taking the chagelebulu stratigraphic profile as a typical example a comprehensive study has been conducted to elucidate the palaeoclimatic and geomorphic evolution patterns in the southern fringe of lie badain jaran desert which were found to be complex and polycyclic in the past 130 ka however the fluctuating magnitude is not as remarkable as that in the eastern china sandy region the shift in climate from interglacial to glacial and the uplift process of the qinghai xizang plateau are the two leading forces driving the evolution of the climate and desert landforms in this area seventeen cycles of cold dry and warm humid climatic stages were recognized in the upper pleistocene series of the profile the sharp uplift of the qinghai xizang plateau superimposed a cool and arid climatic trend in this area as a result of the climatic changes the desert in this area has undergone multiple stages of expansion and contraction since 130 ka bp the middle holocene epoch and the early stage of the late pleistocene period were the main periods when the sand dunes became stabilized and the early and late phases of the holocene epoch and late phase of the pleistocene epoch were the main periods when the previously stabilized sand dunes became mobile the late phase of the pleistocene epoch was the most mobile stage when the aeolian sand activities formed the essential geomorphic pattern if the badain jaran desert copyright c 2005 john wiley sons ltd

high frequency pulses of east asian monsoon climate in the last two glaciations link with the north atlantic three loess sections in the loess plateau of china have been studied to characterize the variations of the east asian monsoon climate in the late quaternary period paleo weathering profiles based on two weathering indices reveal a series of spatially correlative intervals of lower weathering intensity lw in the last glacial and late penultimate glacial loess indicating significantly cooler or and drier conditions most of them are identified at or near the transitional boundaries between loess and soil units suggesting that climatic conditions favorable for lw events tended to occur at or near major climatic boundaries twenty eight radiocarbon and thermoluminescence measurements combined with kukla s magnetic susceptibility age model date these events at 14 21 29 38 52 71 135 and 145 ka bp with 5 10 ka frequency inlaid within the orbitally induced 20 ka periodicity the ages of the first six events in the last glacial period are therefore close to those of the coarse grained heinrich layers in the north atlantic ocean which resulted from massive discharges of icebergs the results indicate that the climate in the area affected by the east asian monsoon has experienced high frequency changes more or less synchronous with the heinrich events these high frequency changes have been reported by porter and an based on the grain size time series from the luochuan loess section our data also reveal that similar events also occurred during the penultimate glaciation the mechanisms linking the heinrich events and the east asian monsoon climate may be similar to that driving the younger dryas event which has been identified in a large number of records in china and in the surrounding oceans

asian summer monsoon instability during the past 60 000 years magnetic susceptibility and pedogenic evidence from the western chinese loess plateau abstract the 28 m high resolution shajinping loess section in lanzhou on the western chinese loess plateau records a 60 ka millennial summer monsoon variation the record shows that asian summer monsoons have rapid episodic pulse enhancements spanning only ca 1 2 ka in high frequency domain and having sub milankovitch cycles of progressive weakening in low frequency domain in the last glaciation soil formation seems to occur with a surprisingly fast response to these summer monsoon enhancements resulting in weakly or moderately developed paleosol sequences both the pattern and timing of the summer monsoon enhancements show that they can be correlated to most major warm dansgaard oeschger episodes and long term cooling bond cycles of the north atlantic climatic records indicating a possible teleconnection between tropic oceanic air masses and the north atlantic climatic system but differences exist for the transition of mis 2 3 and the holocene where extraordinarily heavy dust input events and fairly variable climatic fluctuations occur for the former and latter respectively a westerlies swing model is proposed to interpret this link

optimum sea surface displacement and fault slip distribution of the 2017 tehuantepec earthquake m w 8 2 in mexico estimated from tsunami waveforms

resonance in hawaii waters from the 2006 kuril islands tsunami 1 the 2006 kuril islands tsunami while not destructive to coastal properties resulted in prolonged oscillations in hawaii waters this study examines the oscillation patterns and amplification through reconstruction of the tsunami using a nonlinear shallow water model after validation with water level measurements a fast fourier transform of the computed surface elevation reveals profound oscillation modes at various periods around the hawaiian islands the oscillation at the regional scale consists of standing waves across the island chain and resonance in interconnected channels embayments and shallow shelves resonance in embayments and standing edge waves dominate the oscillation in coastal waters the results show strong correlation between bathymetric features and resonance oscillations and identify tsunami hazard areas for planning and emergency management

validating velocities in the geoclaw tsunami model using observations near hawaii from the 2011 tohoku tsunami the ability to measure predict and compute tsunami flow velocities is of importance in risk assessment and hazard mitigation substantial damage can be done by high velocity flows particularly in harbors and bays even when the wave height is small moreover advancing the study of sediment transport and tsunami deposits depends on the accurate interpretation and modeling of tsunami flow velocities and accelerations until recently few direct measurements of tsunami velocities existed to compare with model results during the 11 march 2011 tohoku tsunami 328 current meters were in place around the hawaiian islands usa that captured time series of water velocity in 18 locations in both harbors and deep channels at a series of depths we compare several of these velocity records against numerical simulations performed using the geoclaw numerical tsunami model based on solving the depth averaged shallow water equations with adaptive mesh refinement to confirm that this model can accurately predict velocities at nearshore locations model results demonstrate tsunami current velocity is more spatially variable than waveform or height and therefore may be a more sensitive variable for model validation

micromorphology of the beiyuan loess paleosol sequence in gansu province china geomorphological and paleoenvironmental significance abstract the 35 5 m thick loess section at beiyuan in gansu province china provides the most detailed record on the loess plateau of the periodicities in earth orbital changes during and since the last interglacial it contains ten paleosols one of which is in the holocene loess four in the malan loess and five in the upper lishi loess and associated alluvium micromorphological study of the s1 paleosol series indicates that all of the component soils were subjected to moderate carbonate leaching and biological activity paleosols s1 c s1 d and s1 e developed in alluvium over a time interval equivalent to stage 5e of the deep sea core v28 238 alluvial deposition was episodic as evidenced by the separation of the paleosols since the development of s1 c the terrace has not been affected by floods and has received only wind blow dust additions the sbc index a ratio of the content of channels and excrements to the content of primary calcite grains appears to be a sensitive indicator of environmental change between the arid and sub humid environments represented by the loess and paleosols respectively the trends periodicities and amplitudes of environmental change revealed by the sbc ratio are in good agreement with those derived from other indices through the beiyuan section and with records from other parts of the world

a 150 000 year climatic record from antarctic ice during much of the quaternary the earth s climate has undergone drastic changes most notably successive glacial and interglacial episodes the past 150 kyr includes such a climatic cycle the last interglacial the last glacial and the present holocene interglacial a new climatic time series for this period has been obtained using 18 o data from an antarctic ice core

kuril islands tsunami of november 2006 2 impact at crescent city by local enhancement 1 crescent city cc is particularly susceptible to tsunami attack the combination of tsunami signal enhancement by both distant bathymetric features and local nearshore resonance seems to be responsible for this behavior application of global tsunami propagation models to the kuril islands tsunami of november 2006 in the companion paper kowalik et al 2008 delineated the importance of distant bathymetric features for both tsunami wave amplification and for increased duration of the tsunami arriving at cc these distant features were responsible for delivering the late high energy signal which was delayed by 2 hours from the predicted arrival time additional local amplification and increased duration are caused by the shelf bathymetry adjacent to cc as the initial tsunami arrives at cc the shelf trapping mechanism tends to excite the gravest of the natural modes this oscillation is slowly shifted toward the natural mode closest to the period of the incident tsunami wave packet short duration wave trains tend to influence the tsunami response at cc harbor in such a way that 1 hour after the first wave arrival a much stronger wave will be generated owing to the tendency of the shelf to initially ring at the frequency of the gravest mode practical implications of distant and local amplification relate to the potential hazard near cc highlighting the need for awareness of the tsunami signal duration in this respect two timescales are important for this event the 2 hour time delay due to distant bathymetric features and the 1 hour delay due to local offshore bathymetry

hydrology and dynamics of a polythermal mostly cold high arctic glacier to improve our understanding of the interactions between hydrology and dynamics in mostly cold glaciers in which water flow is limited by thermal regime we analyse short term every two days variations in glacier flow in the ablation zone of polythermal john evans glacier high arctic canada we monitor the spatial and temporal propagation of high velocity events and examine their impacts upon supraglacial drainage processes and evolving subglacial drainage system structure each year in response to the rapid establishment of supraglacial subglacial drainage connections in the mid ablation zone a spring event of high horizontal surface velocities and high residual vertical motion propagates downglacier over two to four days from the mid ablation zone to the terminus subsequently horizontal velocities fall relative to the spring event but remain higher than over winter reflecting channelization of subglacial drainage but continued supraglacial meltwater forcing further transient high velocity events occur later in each melt season in response to melt induced rising supraglacial meltwater inputs to the glacier bed but the dynamic response of the glacier contrasts with that recorded during the spring event with the degree of spatial propagation a function of the degree to which the subglacial drainage system has become channelized copyright 2006 john wiley sons ltd

hydrostatic versus non hydrostatic modeling of tsunamis with implications for insular shelf and reef environments abstract dispersion is known to separate frequency components and reduce the amplitude of tsunami waves in the open ocean the present paper elucidates a reverse process in which the dispersed wave components from trans oceanic propagation of the 2011 tohoku tsunami regroup over the insular shelves and reefs of hawaii the non hydrostatic and hydrostatic modes of a nonlinear long wave model describe the pertinent processes with and without dispersion using the same system of two way nested grids for direct comparison both solutions have very similar amplitude spectra across the ocean and reproduce the dominant components of recorded surface elevations and currents in hawaii despite their markedly different offshore waveforms the hydrostatic solution shows early arrival of short period signals from nonlinear scattering around the hawaiian islands and faster attenuation of the amplitude due to their local source the short period trailing waves from dispersion more effectively excite shelf and reef oscillations giving rise to better agreement with both the amplitude and phase of the recorded data even with larger offshore wave amplitude a hydrostatic model trends to underestimate the surge elevation and current velocity at coastlines fronted by shallow reefs susceptible to resonance oscillations associated with edge waves

abrupt climatic events recorded by the ili loess during the last glaciation in central asia evidence from grain size and minerals abstract the loess record of central asia provides an important archive of regional climate and environmental changes in contrast to the widely investigated loess deposits in the chinese loess plateau central asian loess paleosol sequences remain poorly understood here we present an aeolian loess section in the southern ili basin based on granularity and mineralogical analyses we reconstruct climatic changes during the last glaciation the results indicated that most of the abrupt climatic events such as dansgaard oeschger events and heinrich events were imprinted in this loess section although their amplitudes and ages showed some differences compared with the millennial oscillations recoded in loess and stalagmites in east asia the arid central asia responded more sensitively to the warming events than to the cooling events the shifting trajectory of westerlies across central asia played an important role in dust deposition during the stadials the north atlantic climatic signals may have been transmitted from central asia to the east asian monsoon regions via the westerlies

chemical models of solute acquisition in glacial melt waters chemical models for the evolution of bulk melt waters can be constructed by assuming that rock mineral weathering and solute acquisition are controlled by carbonate equilibria different open and closed system models are defined by variations in the rates of weathering relative to the rate of hydrogen ion supply by the dissolution and dissociation of co2 and can be recognized by characteristic ph and relationships the observed and inferred compositions of englacial and subglacial melt suggest that mixing is unlikely to be conservative and that closed system conditions result where post mixing weathering reactions occur the final composition of bulk melt waters is determined by the mixing ratio between englacial and subglacial melt the extent of post mixing evolution and opportunity for mixing with ground waters or re equilibration with the atmosphere