three dimensional tomographic model of the crust beneath the hong kong region we present the first three dimensional seismic velocity model of the hong kong region including the dangan island fault zone difz the crust beneath hong kong is predominantly igneous and is characterized by relatively high seismic velocity further south we observe an elongated velocity anomaly beneath part of the difz where significant seismicity has been recorded this anomaly demarcates the contrasting seismic velocity structures on the opposite sides of the fault zone from the surface to a depth of at least 20 km suggesting that the difz extends to the lower crust and dips subvertically our model also indicates that there is an abrupt change in the along strike crustal structure of the fault zone with a significantly higher seismic velocity in the region west of the seismically active area we anticipate that this first three dimensional subsurface tectonic model of hong kong and the difz will help assess the influence of crustal heterogeneities on the spatial pattern of intraplate earthquakes in this densely populated region of south china

carbon delivery to deep mineral horizons in hawaiian rain forest soils 1 this study aimed to better understand the mechanisms for soil organic matter delivery to and accumulation in mineral horizons of tropical rain forest volcanic soils we used soil morphology lysimetry isotopes and spectroscopy to investigate the role of preferential flow paths in the delivery of carbon c to the subsoil high rainfall high primary productivity and the dominance of highly reactive short range order minerals combine to sequester substantial stocks of soil c with long mean residence times the soils have large peds separated by wide cracks which form a network of channels propagating downward through the top 40 to 60 cm facilitating macropore flow the channel infillings and crack surfaces were enriched in organic material om with lower c n ratios and had higher ammonium oxalate extractable al and lower ammonium oxalate extractable fe than the adjacent mineral bulk soil cp mas 13c nmr spectra of om accumulating at depth showed strong signal intensities in the carboxyl and carbonyl c regions indicative of organic acids while decaying roots showed greater contributions of aromatic and o alkyl c the ratios of alkyl to o alkyl c in the organic infillings were more similar to those of the bulk bh and to dissolved organic matter than to those of decaying roots radiocarbon based ages of om infillings at 50 cm depth were significantly younger than the mineral soil 2000 years versus 7000 years respired co2 from incubated soils showed that om accumulating at depth is a mixture of modern and much older c providing further evidence for the downward movement of fresh c

ground motion relations for eastern north america predictive relations are developed for ground motions from eastern north american earthquakes of 4 0 m 7 25 at distances of 10 r 500 km the predicted parameters are response spectra at frequencies of 0 5 to 20 hz and peak ground acceleration and velocity the predictions are derived from an empirically based stochastic ground motion model the relations differ from previous work in the improved empirical definition of input parameters and em pirical validation of results the relations are in demonstrable agreement with ground motions from earthquakes of m 4 to 5 there are insufficient data to adequately judge the relations at larger magnitudes although they are consistent with data from the saguenay m 5 8 and nahanni m 6 8 earthquakes the underlying model parameters are constrained by empirical data for events as large as m 6 8

ocean circulation its effects on seasonal sea ice simulations a diagnostic ice ocean model of the arctic greenland and norwegian seas is constructed and used to examine the role of ocean circulation in seasonal sea ice simulations the model includes lateral ice motion and three dimensional ocean circulation the ocean portion of the model is weakly forced by observed temperature and salinity data simulation results show that including modeled ocean circulation in seasonal sea ice simulations substantially improves the predicted ice drift and ice margin location simulations that do not include lateral ocean movment predict a much less realistic ice edge

ice growth and oceanic heat flux models and measurements heat fluxes at the ice ocean interface and ice thickness are investigated by comparing field data from the coordinated eastern arctic experiment cearex drift phase with model calculations the calculations are based on two types of models the first one is a one dimensional ice ocean model with high vertical resolution this model is based on the conservation equations for heat salt and momentum and uses turbulence models to achieve closure a discrete element approach is also introduced to explicitly parameterize the ice roughness the second model is a simple one dimensional bulk heat transfer model in this version the interfacial salinity is modelled on the basis of salt conservation at the ice ocean interface the bulk heat transfer model is then calibrated using the former model the two models predict ocean heat fluxes that are quite variable in time owing to short term variations in the ice drift both models calculate realistic ice thicknesses it is demonstrated that the observed time variation in ice thickness from eight different experimental sites with varying initial thicknesses and bottom topographies can be reproduced by applying bulk heat transfer coefficients in the range 2 8 1 10 4 horizontal variation of the thermal state within a single pack ice floe results in simultaneous freezing and melting over relatively small spatial scales when modeling or averaging ice data in space these aspects need to be considered

an ice ocean coupled model an ice model an ocean model and a method of coupling the models are described the ice model is a synthesis with variations and extensions of previous modeling ideas ice thickness concentration velocity and internal energy are prognostic variables the ice thermodynamics are represented by temperatures at the snow surface ice surface the interior and the bottom surface melting and freezing rates are calculated at the ice atmosphere ice ocean and atmosphere ocean interfaces a prescribed portion of summer meltwater can be stored on the surface and refrozen in the fall the ocean model includes a second moment turbulence closure submodel and enables one to solve for oceanic heat flux the interfacial stress and subsurface properties in this paper the model is applied to one dimensional simulations but the equations are cited in a form for implementation by two and three dimensional models in a companion paper kantha and mellor this issue the model is used for two dimensional vertical plane simulations in the bering sea several one dimensional sensitivity studies are performed in the case where the ice model is decoupled from the ocean here the oceanic heat flux and sea surface temperature are prescribed constants the studies reveal the role and sensitivity of surface trapped meltwater ice concentration and ice divergence with the coupled ice ocean model the seasonally varying oceanic heat flux and mixed layer properties are determined by the model some comparisons with observations in the central arctic ocean are possible the role of the molecular sublayer immediately adjacent to the ice is examined frazi ice production is related to the large disparity in the molecular diffusivities for temperature and salinity the mixed layer model contains empirical constants which are known from turbulence data the molecular sublayer parameterization requires one empirical parameter b which is uncertain but from this study is assuredly greater than zero the value implicit in previous models the ice model requires the empirical parameters ci f and ci u to quantitatively account for freezing or melting processes in open leads their values are also uncertain but we present reasoning and sensitivity studies to suggest specific values finally an empirical parameter g is introduced it is the ratio of the value of the ice thickness used to represent average ice volume in the dynamic and thermodynamic equations to the value of the thickness needed in the heat conduction equation estimates of g are made from observed thickness distribution functions sensitivity studies show it to be an important parameter

site amplifications for generic rock sites seismic shear wave velocity as a function of depth for generic rock sites has been estimated from borehole data and studies of crustal velocities and these velocities have been used to compute frequency dependent amplifications for zero attenuation for use in simulations of strong ground motion we define a genetic rock site as one whose velocity at shallow depths equals the average of those from the rock sites sampled by the borehole data most of the boreholes are in populated areas for that reason the rock sites sampled are of particular engineering significance we consider two genetic rock sites rock corresponding to the bulk of the borehole data and very hard rock such as is found in glaciated regions in large areas of eastern north america or in portions of western north america the amplifications on rock sites can be in excess of 3 5 at high frequencies in contrast to the amplifications of less than 1 2 on very hard rock sites the consideration of unattenuated amplification alone is computationally convenient but what matters for ground motion estimation is the combined effect of amplification and attenuation for reasonable values of the attenuation parameter k 0 the combined effect of attenuation and amplification for rock sites peaks between about 2 and 5 hz with a maximum level of less than 1 8 the combined effect is about a factor of 1 5 at 1 hz and is less than unity for frequencies in the range of 10 to 20 hz depending on t using these amplifications we find provisional values of about ao 70 bars and k 0 0 035 sec for rock sites in western north america by fitting our empirically determined response spectra for an m 6 5 event to simulated values the borehole data yield shear velocities 033o of 618 and 306 rrdsec for rock and soil sites respectively when averaged over the upper 30 m from this we recommend that v30 equals 620 and 310 m sec for applications requiring the average velocity for rock and soil sites in western north america by combining the amplifications for rock sites and the site factors obtained from our analysis of strong motion data we derive amplifications for sites with 17 3o 520 m sec nehrp class c corresponding to a mix of rock and soil sites and v3o 310 and 255 m sec average soil and nehrp class d sites respectively for the average soil site the combined effect of amplification and attenuation exceeds a factor of 2 0 for frequencies between 0 4 and about 4 hz with a peak site effect of 2 4 the peak of the nehrp class d site effect is 2 7

storage and depth distribution of organic carbon in volcanic soils as affected by environmental and pedological factors abstract it has been recognised that volcanic soils particularly andosols can store large amounts of soil organic carbon soc this study investigates the factors controlling the regional and vertical distributions of soc in soils of volcanic origin to this aim we investigated the vertical distribution of soc in a total of 212 soil profiles representing all combinations of soil forming factors in a volcanic area with a high diversity of ecosystems and soil types we analysed the soc contents in relation to intrinsic soil type and relevant soil properties texture and ph and extrinsic factors climate parent material relief and we studied the patterns of soc distribution with depth by fitting the soc contents to different curve models furthermore we selected ten soil profiles for a more detailed study to assess the effect of vegetation by examining the relationships of the soc storage and depth distribution to the amount and allocation of plant roots and litterfall soc storage was controlled by the interaction of climatic rainfall time substrate age topographic slope and biotic plant mediated factors our results indicate that under humid conditions large organic inputs and the inhibition of microbial degradation due to low ph al toxicity and persistent anaerobiosis within soil microaggregates largely contributed to soc accumulation soil type was a poor predictor of soc storage most likely due to the co occurrence of young and evolved andosols and a certain andic character in many soils that did not qualify as andosols the distributions of root carbon and soc appeared to be closely interrelated suggesting a major role of roots in the supply of organic matter and the lack of significant bioturbation the depth distribution of soc was best fitted by the quadratic cubic and power models the latter being a feasible alternative that should be used to this aim in volcanic soils rather than the widely used exponential model

greenland sea convection in the winter of 1987 1988 during february 1988 a layer of almost uniform temperature and salinity between 100 and 1250 m depth was observed in the central greenland sea this feature indicative of previous deep convection is explained in terms of a conceptual penetrative convection model

earthquake frequency distribution and the mechanics of faulting the level of intraplate seismicity in japan generally shows a positive correlation with the density of quaternary faulting in southwest japan where intraplate seismicity is concentrated on land rates of seismic moment release m 0 are similar when calculated from either the 400 year historical record of seismicity or geologically determined slip rates of quaternary faults a data set of 18 earthquakes with seismic moments m0 ranging from 0 01 to 3 1027 dyn cm shows a relationship between rupture lengthl and m0 log m0 23 5 1 94 log l when seismic moment on each quaternary fault is assumed to occur in discrete events every t m0 m 0g years where m0 is estimated for a rupture extended over the entire fault length and m 0g is proportional to the slip rate of each quaternary fault the moment frequency distribution of earthquakes log n a b log m0 predicted from the geologic record is virtually identical to that seen with the 400 year record of seismicity in contrast if it is assumed that earthquakes on each fault occur according to the gutenberg richter relation we obtain poor agreement with the observed seismicity thus while regional seismicity satisfies the relation log n a b log m0 or equivalently log n a b log m where m is magnitude it appears that seismicity on individual faults does not this further implies that the primary factor that leads to the magnitude frequency distribution in regional seismicity studies is the relative distribution of the slip rates and lengths of preexisting faults

on the parameterisation of oceanic sensible heat loss to the atmosphere and to ice in an ice covered mixed layer in winter abstract in high latitude oceans with seasonal ice cover the ice and the low salinity mixed layer form an interacting barrier for the heat flux from the ocean to the atmosphere the presence of a less dense surface layer allows ice to form and the ice cover reduces the heat loss to the atmosphere the ice formation weakens the stability at the base of the mixed layer leading to stronger entrainment and larger heat flux from below this heat transport retards and perhaps stops the growth of the ice cover as much heat is then entrained from below as is lost to the atmosphere this heat loss further reduces the stability and unless a net ice melt occurs the mixed layer convects two possibilities exist 1 a net ice melt sufficient to retain the stability will always occur and convection will not take place until all ice is removed the deep convection will then be thermal deepening the mixed layer 2 the ice remains until the stability at the base of the mixed layer disappears the mixed layer then convects through haline convection into the deep ocean warm water rises towards the surface and the ice starts to melt and a new mixed layer is reformed the present work discusses the interactions between ice cover and entrainment during winter when heat loss to the atmosphere is present one crucial hypothesis is introduced when ice is present and the ocean loses sensible heat to the atmosphere and to ice melt the buoyancy input at the sea surface due to ice melt is at a minimum using a one dimensional energy balance model applied to the artificial situation where ice melts directly on warmer water it is found that this corresponds to a constant fraction of the heat loss going to ice melt it is postulated that this partitioning holds for the ice cover and the mixed layer in the high latitude ocean when a constant fraction of heat goes to ice melt at least one deep convection event occurs before the ice cover can be removed by heat entrained from below after one or several convection events the ice normally disappears and a deep reaching thermal convection is established conditions appropriate for the weddell sea and the greenland sea are examined and compared with field observations with realistic initial conditions no convection occurs in the warm regime of the weddell sea a balance between entrained heat and atmospheric heat loss is established and the ice cover remains throughout the winter at maud rise convection may occur but late in winter and normally no polynya can form before the summer ice melt in the central greenland sea the mixed layer generally convects early in winter and the ice is removed by melting from below as early as february or march this is in agreement with existing observations

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

importance of convective mixing in seasonal ice margin simulations a two dimensional ice ocean model applicable to the greenland sea is constructed and used to examine the role of penetrative convection in the seasonal advance and retreat of the sea ice margin the standard version of the model is based on the full dynamic and thermodynamic equations of sea ice and on the primitive equations discretized on a vertical slab for the ocean it includes a special treatment of upper ocean vertical mixing based on a parameterization of entrainment at the bottom of the ocean mixed layer the simulation results with this standard version of the model show that when ice advection is included with ice moving outward over open water penetrative convection delays and greatly reduces the ice edge advance the resulting seasonal ice distribution yields better agreement with observation than a simulation that does not allow mixed layer entrainment when lateral heat transport is neglected in the ocean the ice margin again moves too a great extent outward this result demonstrates that in addition to vertical mixing a heat source must exist in the ocean mixed layer in order to resist and ultimately stop the advection of ice finally in the absence of ice motion penetrative convection has a less pronounced effect on the ice edge location

the role of plastic ice interaction in marginal ice zone dynamics under appropriate conditions the nonlinear nature of plastic ice interaction together with a nonlinear coupling between ice thickness characteristics and ice rheology can substantially modify the character of marginal ice zone dynamics this paper examines the steady state ramifications of these nonlinearities by using a one dimensional simplification of hibler s 1979 two level viscous plastic sea ice model a series of idealized small scale simulations 4 km resolution are carried out with the model formulated in a moving lagrangian grid in order to remove diffusion effects analytic solutions for the equilibrium plastic adjustment case are also constructed the results show that if the ice thickness distribution is allowed to equilibrate in response to a constant wind field the thickness strength coupling will yield a sharp ice edge with the compactness dropping rapidly to zero near the ice margin despite this compactness falloff the steady adjusted ice velocity is nearly constant across the marginal ice zone however the adjustment to a steady state constant velocity can be preceded by a period of shearing which will abate as the ice strengthens by ridging with an increase in forcing near the edge the ice velocity scales with the wind velocity but with a speed less than free drift in the absence of water drag and wind stress the model exhibits a very slow outward creep but yields no ice edge jet effects the ramifications of plastic interaction on upwelling and downwelling are also examined with the same drag coefficients over ice and ocean and for a north south ice edge the model yields in the northern hemisphere upwelling for northward winds downwelling for southward winds and no effect for off ice winds

comparison of seismic waveform inversion results for the rupture history of a finite fault application to the 1986 north palm springs california earthquake the july 8 1986 north palm springs earthquake is used as a basis for comparison of several different approaches to the solution for the rupture history of a finite fault the inversion of different waveform data is considered both teleseismic p waveforms and local strong ground motion records linear parametrizations for slip amplitude are compared with nonlinear parametrizations for both slip amplitude and rupture time inversions using both synthetic and empirical green s functions are considered in general accurate green s functions are more readily calculable for the teleseismic problem where simple ray theory and flat layered velocity structures are usually sufficient however uncertainties in the variation in t with frequency most limit the resolution of teleseismic inversions a set of empirical green s functions that are well recorded at teleseismic distances could avoid the uncertainties in attenuation in the inversion of strong motion data the accurate calculation of propagation path effects other than attenuation effects is the limiting factor in the resolution of source parameters the assumption of a laterally homogeneous velocity structure is usually not a good one and the use of empirical green s functions is desirable considering the parametrization of the problem any degree of fault rupture complexity can be described in terms of a linear parametrization for slip amplitudes however a nonlinear parametrization for rupture times and slip amplitudes can have a distinct advantage over a simple linear one by limiting the number of unknown parameters regardless of the choice of data or the type of parametrization the model or solution will be affected by the choice of minimization norm and the type of stabilization used

ice seawater turbulent boundary layer interaction with melting or freezing abstract a second moment turbulence closure model is applied to the problem of the dynamic and thermodynamic interaction of sea ice and the ocean surface mixed layer in the case of ice moving over a warm ocean surface layer melting is intrinsically a transient process that is melting is rapid when warm surface water initially contacts the ice then the process slows when surface water is insulated from deeper water due to the stabilizing effect of the melt water and the thermal energy stored in the surface layer is depleted effectively the same process prevails when ocean surface water flows under stationary ice in which case after an initial rapid increase the melting process decreases with downstream distance accompanying the stabilizing effect of the melt water is a reduction in the ice seawater interfacial shear stress this process and model simulators are used to explain field observations wherein ice near the marginal ice zone diverges from the main pack when the surface ice layer is m

a model study of upper ocean sea ice interactions abstract a thermodynamic sea ice model including leads has been coupled to a one dimensional oceanic mixed layer model in order to investigate the upper ocean sea ice interactions the oceanic heat flux at the base of the ice layer fb is predicted not imposed assuming a thermodynamic equilibrium between the bottom of the ice and the water just below for testing of the model the annual cycle of the arctic sea ice and upper ocean is simulated along longitude 169 5 w the model produces a realistic evolution of the sea ice thickness and extent and of the upper mean salinity and temperature profiles the major deficiencies in the simulation are linked to the absence of ocean and ice dynamics the modeled value of fb is far from being constant below thin ice it can be larger than 5 w m 2 due to the important fraction of the solar irradiance that is transmitted through the ice absorbed in the mixed layer and then returned to the ice below the thicker perennial sea ice fb takes values between 0 and

regional tectonic setting of hong kong implications of new gravity models hong kong lies on the se margin of the cathaysia block and straddles the ne trending lianhuashan fault zone one of the dominant structural features of se china isotope signatures of the mesozoic granites have indicated that the zone overlies a major crustal discontinuity the proposed gravity model of hong kong consists of a heterogeneous upper crust underlain by middle to lower crust composed of a felsic archaean segment approximately 25 km wide flanked by more mafic proterozoic crust the southern boundary of the felsic segment dips steeply to the north whereas the northern boundary is subvertical euler gravity anomalies define the fundamental faults in the upper crust and many of these can be correlated with faults that have been mapped at surface the middle to lower crustal discontinuities are considered to be associated with a major shear zone within the cathaysia block that has similar dimensions to transcratonic structures in other precambrian shield areas the geological development of hong kong and neighbouring se china has largely been controlled by periodic reactivation of this deep crustal shear zone since the late neoproterozoic

a diagnostic ice ocean model abstract a coupled ice ocean model suitable for simulating ice ocean circulation over a seasonal cycle is developed by coupling the dynamic thermodynamic sea ice model of hibler with a multilevel baroclinic ocean model bryan this model is used to investigate the effect of ocean circulation on seasonal sea ice simulations by carrying out a simulation of the arctic greenland and norwegian seas the ocean model contains a linear term that damps the ocean s temperature and salinity towards climatology the damping term was chosen to have a three year relaxation time equivalent to the adjustment time of the pack ice no damping however was applied to the uppermost layer of the ocean model which is in direct contact with the moving pack ice this damping procedure allows seasonal and shorter time scale variability to be simulated in the ocean but does not allow the model to drift away from ocean climatology on longer time scales for the standard experiment an initial integration of five years was per

bottom ablation and heat transfer coefficients from the 1983 marginal ice zone experiments bottom ablation in the marginal ice zone miz is a fundamental process that controls the ice edge position in both the winter and the summer during the east and west marginal ice zone experiments mizex west and mizex east in 1983 periodic sonic distance measurements between the overlying ice and transducers fixed on masts below ice floes determined the bottom ablation the melt rates for floes within 15 km of the ice edge ranged from near zero when the ice was in water at the freezing point to 0 5 m d 1 when the ice entered warm water greater than 3 k to the south simultaneous velocity and temperature measurements at 2 m below the ice in mizex west and at 2 m and 10 m below the ice in mizex east show the response of the melt rate to changing oceanographic conditions for the first time the combined oceanographic and ablation measurements allow the direct calculation of the bulk heat transfer coefficient ch between the ice and the ocean at 2 m and 10 m below the ice for the bering sea experiment ch was 8 10 4 while for the fram strait experiment ch varied from 2 10 4 to 4 10 4 within each set of experiments ch remained nearly constant over a wide range of melt rates relative ice water speeds and seawater temperatures

the thermohaline circulation of the arctic ocean and the greenland sea the thermohaline circulation of the arctic ocean and the greenland sea is conditioned by the harsh high latitude climate and by bathymetry warm atlantic water loses its heat and also becomes less saline by added river run off in the arctic ocean this leads to rapid cooling of the surface water and to ice formation brine released by freezing increases the density of the surface layer but the ice cover also insulates the ocean and reduces heat loss this limits density increase and in the central arctic ocean a low salinity surface layer and a permanent ice cover are maintained only over the shallow shelves where the entire water column is cooled to freezing can dense water form and accumulate to eventually sink down the continental slope into the deep ocean the part of the atlantic water which enters the arctic ocean is thus separated into a low density surface layer and a denser deep circulation these two loops exit through fram strait the waters are partly rehomogenized in the greenland sea the main current is confined to the greenland continental slope but polar surface water and ice are injected into the central gyre and create a low density lid allowing for ice formation in winter this leads to a density increase sufficient to trigger convection upwelling and subsequent ice melt the convection maintains the weak stratification of the gyre and also reinforces the deep circulation loop as the transformed waters return to the north atlantic the low salinity upper water of the east greenland current enters the labrador sea and influences the formation of labrador sea deep water the dense loop passes through denmark strait and the faroe shetland channel and sinks to contribute to the north atlantic deep water changes in the forcing conditions might alter the relative strength of the two loops this could affect the oceanic thermohaline circulation on a global scale

aluminium stabilization controls organic carbon levels in chilean volcanic soils chilean volcanic soils are known to contain large amounts of organic matter om and amorphous e g allophanic clay here we test the hypothesis that al rather than clay content and climatic conditions is the most important factor for om levels in volcanic soils this was achieved by compiling a total of 225 pedons from two national wide datasets of south central chilean soils sampled in the first 20 cm depth all selected soils are of volcanic origin previously under native nothofagus forest and now used as pasture or arable land the relationships between soil organic c from now soil c and environmental and soil characteristics clay allophane al content were analysed by simple and multiple linear regression analyses soils classify as alfisols andisols inceptisols and ultisols al was extracted by kcl alk acid ammonium acetate ala and acid ammonium oxalate alo the simple regression models showed that ala correlated best r 2 0 52 with soil c variations for the four soil orders studied while alk r 2 0 08 and alo r 2 0 17 were poorly correlated in all soils types especially in inceptisols ala was highly correlated with soil c r 2 0 88 clay content and hence allophanic content was poorly correlated with soil c r 2 0 14 as was the mean annual precipitation r 2 0 21 and temperature r 2 0 15 these patterns were supported by the multiple regression analyses results therefore support the idea that al is the principal factor for immobi lization of om in acid volcanic soils as ammonium acetate extractable al at ph 4 8 correlated well with om and as this is a rarely used method to interpret pedogenic processes this extraction method warrants further attention d 2005 elsevier b v all rights reserved

hybrid simulations of ground motions from local earthquakes affecting hong kong hong kong is located in a continental intraplate region within southeastern china historical records indicate that hong kong has been affected by both moderate local earthquakes and major distant ones but recent probabilistic seismic hazard analyses psha showed that the seismic hazard in hong kong was mainly dominated by strong and major earthquakes at distances between 90 and 400 km from the city further investigation on the result of the psha reveals that the conventional gutenberg richter seismicity model used in the psha may have underestimated the probability of occurrence of local large magnitude earthquakes the fact that the dangan island fault which has generated a moderate earthquake in 1874 lies only 30 km southeast of hong kong warrants a thorough investigation on the likely ground motion intensities that may be produced by local earthquakes in the future although the seismogenic potential of the dangan island fault has not been assessed definitely it could perhaps generate an m max 7 earthquake a series of ground motion simulations are carried out using a hybrid kinematic stochastic model to estimate the peak ground accelerations pgas peak ground velocities pgvs and response spectral accelerations rsas at eight representative locations within hong kong the capability of the simulation model and the appropriateness of the key parameters used in the simulations are confirmed by simulating the ground motions recorded in hong kong during a recent microearthquake on the dangan island fault the results of the simulations are used to derive a set of attenuation relationships for pga pgv and rsa that will be essential for future probabilistic and deterministic seismic hazard analyses using the spectral attenuation relationship derived it is revealed that strong earthquakes with m w 6 0 6 5 along the dangan island fault rather than major distant earthquakes m w 7 3 r 340 km would dominate the seismic hazard in hong kong for natural periods longer 1 sec which correspond to the natural periods of most buildings in hong kong it is therefore timely for the authority to initiate a series of geological investigations to determine the slip rate of the fault system more precisely to access the actual seismogenic potential of the dangan island fault

late holocene paleopedological records contained in tephra from el chichon volcano chiapas mexico abstract high rates of pedogenesis on unconsolidated volcanic materials imply the accelerated generation of the soil memory the purpose of this research was to extract the high resolution centennial scale paleopedological records from the late holocene paleosols of the el chichon volcano formed during the last 2000 years we studied buried monogenetic andosols on the dated tephras and a pedocomplex formed from a set of thin ash layers deposited on older acrisol derived from shales particle size distribution dcb extractable fe oxalate extractable fe al and si sand and clay mineralogy organic carbon content and stable c isotope composition in humus were evaluated and interpreted as the elements of the soil memory however some differences were found in properties of two buried soils especially in the kind of a horizons we attribute such differences of individual andosols to be caused by ancient human impact because it has been demonstrated that humid conditions persisted during the last 1300 years thus the drought that was supposed to provoke the collapse of the maya civilization at the end of i millennium a d should have been a short term event below the resolution of this paleopedological record the andic acrisol pedocomplex demonstrated the domination of the humid tropical climate over longer time intervals probably major part of the holocene with possible minor dry episodes

modeling the seasonal variation of sea ice in the labrador sea with a coupled multicategory ice model and the princeton ocean model we use a multicategory sea ice model coupled to the princeton ocean model which is driven by monthly climatological atmospheric forcing to study the seasonal variation of ice cover in the labrador sea initial ocean conditions are derived from a gridded objectively analyzed temperature salinity data set that provides improved resolution of gradients in the vicinity of the shelf break the model produces a realistic seasonal variation of sea ice there is ice growth over the inner shelf and ice melt over the outer shelf and slope over the inner shelf advection and diffusion decrease the ice mass over the outer shelf advection and diffusion increase the ice mass which maintains the location of the ice edge near the offshore ice edge the melt rate exceed s1mp er month and the heat to melt ice together with the heat lost to the atmosphere exceeds 500 wm 22 the heat lost at the ocean surface is compensated for by advection of heat from an offshore convective region the dominant heat source for the spring retreat of ice in the south is shortwave radiation over the open water fraction marginal ice zones are regions of dynamic interaction be tween atmosphere ice and ocean in the labrador marginal ice zone the ice edge is located near the labrador current and its associated shelf break front wintertime convection in the western labrador sea is thought to form labrador intermedi ate water clarke and gascard 1983 since the ice edge bor ders the convective region it is important to clarify the pro cesses that limit the ice extent and to examine the heat and salt fluxes in the vicinity of the ice edge in this study we investigate the seasonal evolution of sea ice over the labrador shelf with a coupled ice ocean model our objective is to assess the capability of the model in simulating the evolution of the ice cover and to identify model deficien cies we examine the processes that limit the ice extent labrador sea ice has been the subject of a number of studies with numerical models most recently ikeda et al 1996 cou pled a two category ice model hibler 1979 with the geo physical fluid dynamics laboratory gfdl ocean model bryan 1969 cox 1984 there was overall agreement with the seasonal cycle as well as with interannual variations the re sults showed that shoreward advection of relatively warm off shore water is an important source of heat to melt ice how ever the model ice decayed too rapidly partly because the two category ice model underestimates ice concentration there are a number of differences between the present model and the model of ikeda et al 1996 we have imple mented a multicategory ice model and used the sigma coordi nate princeton ocean model blumberg and mellor 1987 mel lor 1996 with its embedded turbulence closure submodel we use a climatology from the national centers for environmen tal prediction ncep national center for atmospheric re

a coupled sea ice mixed layer pycnocline model for the weddell sea a dynamic thermodynamic sea ice model is coupled to a one dimensional model of the oceanic mixed layer and pycnocline and is applied to the weddell sea this model prognostically determines the vertical oceanic heat flux from the mixed layer dynamics in contrast to earlier sea ice modeling where the oceanic heat flux was prescribed in addition to the standard simulation polynya and paleoclimate experiments were performed to investigate the effects of sea ice dynamics furthermore the mixed layer pycnocline model is compared to the original kraus turner approach

numerical simulation of northern hemisphere sea ice variability 1951 1980 the dynamic thermodynamic sea ice model of hibler 1979 is used to simulate northern hemisphere sea ice growth drift and decay over a 30 year period 1951 1980 the model is run with a daily time step and is forced by interannually varying fields of geostrophic wind and temperature derived thermodynamic fluxes the results include documentation of the sensitivities to the source of the thermodynamic forcing data and to the number of thickness levels in the thermodynamic formulation the fields of ice velocity and thickness show strong seasonal as well as interannual variability the pacific gyre is found to be well developed in spring and autumn but less so in winter and summer the mean drift pattern results in thicknesses of 4 5 m offshore of northern canada and greenland while winter thicknesses of 2 m are typical of the alaskan and eurasian coastal waters annual net growth ranges from 0 1 to 0 6 m over much of the arctic basin and baffin bay to over 1 0 m in the eastern bering sea annual net melt of 0 5 1 5 m occurs in the western bering sea and the north atlantic marginal ice zone no significant temporal trends are detectable in the total mass of simulated ice the simulated interannual fluctuations in 20 longitudinal sectors correlate at 0 4 0 9 with corresponding observed fluctuations during 1961 1976 the correlations are smaller when dynamics are omitted from the model the simulated velocities show no bias but considerable scatter relative to the drift of the arctic buoys in 1979 and 1980 an analysis of the regional mass budgets shows that the normal seasonal cycle is controlled primarily by the thermodynamic processes but that the thickness anomalies in much of the arctic are attributable primarily to dynamic processes during winter spring and autumn thermodynamic processes contribute more strongly to summer anomalies and to anomalies near the ice edge the tendency for ice anomalies to be advected by the pattern of mean drift is apparent in multiseason lag correlations involving subregions of the arctic basin and the peripheral seas the simulated outflows of ice mass through the fram and bering straits vary by factors of 2 3 in successive years the simulated outflow in the fram strait is 20 30 smaller when ocean currents are omitted from the model

sensitivity of simulated cfc 11 distributions in a global ocean model to the treatment of salt rejected during sea ice formation we show that simulated oceanic absorption of an atmospheric gas is very sensitive to the representation of a process that occurs beneath sea ice as sea ice forms salt is rejected locally increasing surface sea water density this dense water can sink to the pycnocline at the base of the mixed layer previous studies have not considered the impact of this subgrid scale process on transient tracers in the ocean to assess the potential importance of this process to the oceanic absorption of atmospheric gases we performed two idealized simulations a control simulation in which salt rejected during sea ice formation is placed in the model s 25 m thick surface layer and a test simulation in which salt rejected during sea ice formation is distributed uniformly through the upper 160 m beneath the forming sea ice our treatment of rejected salt is highly idealized and is intended to demonstrate the need for a physically based parameterization of subgrid scale convection for use in ocean general circulation models that takes into account the subgrid scale heterogeneity of surface buoyancy forcing distributing rejected salt more deeply during periods of ice formation helps to maintain vertical density gradients inhibiting grid scale convection especially in the southern ocean this greatly diminishes simulated ocean uptake of cfc 11 and generally improves simulated cfc 11 and salinity fields the modeled global ocean inventory of cfc 11 for year 1990 is about 30 lower and modeled column inventories in the southern ocean are up to 90 lower in our test simulation relative to our control simulation we infer that a more detailed treatment of subgrid scale processes occurring beneath sea ice may diminish simulated oceanic absorption of anthropogenic co2 especially in the southern ocean

regional and local factors in attenuation modelling hong kong case study seismic attenuation behaviour is controlled by a large number of wave modification mechanisms the characteristics of some of these mechanisms are specific to a local area whilst the remainder can be generalised to the entire seismic region factors representing these mechanisms are often not resolved a new attenuation modelling approach is demonstrated in this paper using hong kong as a case study to evaluate individual regional and local wave modification factors shear wave velocity swv information for the four prevalent geological formations found in hong kong was first obtained a at shallow depths from instrumented boreholes b at depths of up to 100 200 m from measurements using the microtremor spatial auto correlation spac technique c at depths of up to 1 5 km from the monitoring of quarry blasts and d at depths from 1 5 to 8 km in the hard basement rock layers from results of seismological refraction surveys the upper crust amplification factor calculated from the four modelled rock swv profiles was then combined with predicted attenuation parameters to determine the upper crust modification factor filter function incorporating the local wave modification characteristics associated with hong kong geological formations such functions may then be combined with the regional attenuation characteristics in that part of the south china region a seismic attenuation model was developed by combining the upper crust modification factor with the regional source function of intra plate earthquakes based on stochastic simulations the ground shaking model developed from the presented methodology is supported by the comparison with macro seismic data of seven historical earthquake events affecting hong kong

long term controls on soil organic carbon with depth and time a case study from the cowlitz river chronosequence wa usa abstract over timescales of soil development millennia the capacity of soils to stabilize soil organic carbon soc is linked to soil development through changes in soil mineralogy and other soil properties in this study an extensive dataset of soil profile chemistry and mineralogy is compiled from the cowlitz river chronosequence crc wa usa the crc soils range in age from 0 25 to 1200 kyr spanning a developmental gradient encompassing clear changes in soil mineralogy chemistry and surface area comparison of these and other metrics of soil development with soc properties reveal several relationships that may be diagnostic of the long term coupling of soil development and c cycling specifically soc content was significantly correlated with sodium pyrophosphate extractable metals emphasizing the relevance of organo metal complexes in volcanic soils the depth distributions of organo metals and other secondary weathering products including the kaolin and short range order sro minerals support the so called binary composition of volcanic soils the formation of organo metal complexes limits the accumulation of secondary minerals in shallow soils whereas in deep soils with lower soc content secondary minerals accumulate in the crc soils secondary minerals formed in deep soils below 50 cm including smectite allophane fe oxides and dominated by the kaolin mineral halloysite the abundance of halloysite was significantly correlated with bulk soil surface area and 14 c content a proxy for the mean age of soc implying enhanced stability of c in deep soils allophane an sro mineral commonly associated with soc storage was not correlated with soc content or 14 c values in crc soils we propose conceptual framework to describe these observations based on a general understanding of pedogenesis in volcanic soils where soc cycling is coupled with soil development through the formation of and fate of organo metal or other mobile weathering products this framework highlights interactions between soc and soil development which may be applicable to other soils where organic inputs interact with the products of chemical weathering

a coupled one dimensional sea ice ocean model a prognostic one dimensional mixed layer pycnocline model describing the vertical structure of the upper ocean is coupled to a thermodynamic sea ice model the coupled prognostic model is compared with the more usual sea ice model overlying a fixed mixed layer with constant oceanic heat flux and is then applied to investigate the effect of temporal and regional variations of the entrained oceanic heat flux on the sea ice cover in both polar regions in the southern ocean a standard simulation is compared with two perturbation experiments which both describe the occurrence of a polynya in the arctic ocean the effect of possible soviet river diversions is investigated finally the response of the coupled model to paleoclimatic forcing and boundary conditions is presented

are organo mineral complexes and allophane content determinant factors for the carbon level in chilean volcanic soils abstract the existing information on soil carbon c stabilisation in allophanic soils is conflicting because active al3 and sesquioxides i e the oxides hydroxides of al and fe as a stabilising agent of soil c are emphasised in opposition to allophane and imogolite type materials two hypotheses were tested in this study 1 al and fe complexed with soil c and allophane content are the key variables to explain the soil c level in chilean allophanic soils and 2 the existing metal som complex and short range ordered aluminosilicate minerals in allophanic soils mainly result from soil ph variation and competition between al and fe for som and allophane formation this study established the relationship among different soil properties such al fe complexes and allophane content on soil c levels in chilean volcanic soils as well as the effect of soil ph on metal om complexes a total of 45 soil samples from 15 soil pedons were sampled at 0 0 1 0 1 0 2 and 0 2 0 4 m the soil samples were analysed for the content of soil organic c allophane clay silt and na pyrophosphate extraction alp fep cp and soil ph water we examined the relationship between the soil c content and soil properties using simple and multiple linear regressions the silt and clay contents explained little while the allophane soil ph and alp explained most of the soil c variation we found an inverse relationship between soil ph and alp and fep indicating that the soil ph was significantly correlated with alp and fep while the allophane content was positively related with soil ph the results also showed a higher atomic ratio al fe p cp in deep 0 2 0 4 m horizons the opposite was true in the top soil horizon 0 0 1 m supporting the idea that som in deep soils is saturated with al and fe leaving extra metal to react with silica for allophane formation

heat flux at the ice ocean interface the role of the oceanic heat flux fw in the sea ice energy and mass balance is discussed and a method is described for determining fw from measurements of the temperature and thickness of sea ice results obtained using this method and data collected in the fall of 1988 during a drift in the eastern arctic northeast of fram strait are presented estimates of fw ranged from 0 to 37 w m 2 and varied in both time and space the gradual variation over the course of the drift reflects transformation of the west spitsbergen current into arctic water masses a significant intersite variability on horizontal scales of 10 to 100 m is ascribed to the interaction between under ice topographic features and turbulent energy and mass transfer in the boundary layer in addition there is a variability in the ice growth rate on horizontal scales of 0 1 to 1 m which is ascribed to the instability of the ice ocean phase boundary in the presence of turbulent flow these observations have implications for modeling and future experiments

testing a coupled ice mixed layer model under subarctic conditions abstract a one dimensional oceanic mixed layer model has been coupled with a thermodynamic sea ice model in order to study the seasonal cycle of ice ocean interaction in the subarctic ocean the ice thickness is assumed constant and only variations of ice compactness under the effect of the atmospheric and oceanic heat fluxes are considered the mixed layer model allows prediction of the rate of entrainment mainly as the result of the penetrative buoyancy driven convection both heat and salt conservation equations are included so that the respective efficiency with regard to vertical mixing of brine rejection below the ice and intense surface cooling in open water can be compared the model has been run for ten years on a zonal vertical section across the greenland sea the annual entrainment retreat cycle of the mixed layer is well reproduced with maximum depths occurring in late winter even down to the bottom at some locations near the ice edge surface cooling is found to be a more efficient mecha

the effect of ice pressure on marginal ice zone dynamics to evaluate the role of compressive ice pressure in marginal ice zone dynamics a cavitating fluid model with periodic boundaries is developed and subjected to a fixed wind field and both cyclonic and anticyclonic wind vortices in this model ice interaction is approximated by assuming that sea ice has no resistance to divergence or shear but has some compressive strength which is taken to be a linear function of compactness time scales of ice pressure effects are examined and their relevance to ocean eddies is discussed

weathering and soil formation in rhyolitic tephra along a moisture gradient on alcedo volcano galapagos abstract the galapagos archipelago has extensively been studied because of its geological and climatic setting and especially for its peculiar flora and fauna however there is still little information about its soils the objective of this study was to investigate weathering and soil formation on alcedo volcano which is the only volcano of galapagos that has erupted abundant rhyolitic materials soils were sampled from three sites along an elevation moisture gradient site 1 at 872 m above sea level a s l humid zone site 2 at 621 m a s l dry zone and site 3 at 377 m a s l very dry zone soil ph in h2o ranged from 6 0 to 6 6 but did not vary significantly among the three sites water retention at 1500 kpa and phosphate retention increased with elevation moisture similarly soil organic carbon soc stocks increased from approx 1 1 kg m 2 in the very dry zone to approx 7 5 kg m 2 in the humid zone allophane and ferrihydrite were the dominant colloidal constituents in the humid zone site 1 whereas halloysite was found in the dry zone site 2 and only traces of halloysite in the very dry zone site 3 at site 1 the soil was borderline between andic and vitric properties and was classified as silandic tephric andosol or vitric tephric andosol for andic and vitric character respectively at site 2 the soil had vitric properties and was classified as vitric tephric skeletic andosol and at site 3 the soil was borderline with respect to the expression of vitric properties and was classified as vitric tephric skeletic andosol in the presence and as tephric skeletic regosol in the absence of vitric properties our results show that different moisture availability strongly affected soc accumulation and favored the formation of different types of colloidal constituents amorphous vs crystalline in the rhyolitic tephra of alcedo volcano this has important bearings on the expression of andic and vitric soil properties and hence on the distribution of andosols in the studied environment

fault behavior and characteristic earthquakes examples from the wasatch and san andreas fault zones paleoseismological data for the wasatch and san andreas fault zones have led to the formulation of the characteristic earthquake model which postulates that individual faults and fault segments tend to generate essentially same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum analysis of scarp derived colluvium in trench exposures across the wasatch fault provides estimates of the timing and displacement associated with individual surface faulting earthquakes at all of the sites studied the displacement per event has been consistently large measured values range from 1 6 to 2 6 m and the average is about 2 m on the basis of variability in the timing of individual events as well as changes in scarp morphology and fault geometry six major segments are recognized along the wasatch fault on the basis of the most likely number of surface faulting events 18 that have occurred on segments of the wasatch fault zone during the past 8000 years an average recurrence interval of 400 666 years with a preferred average of 444 years is calculated for the entire zone geologic data on the distribution of slip associated with prehistoric earthquakes and slip rates along the south central segment of the san andreas fault suggest that the m 8 1857 earthquake is a characteristic earthquake for this segment comparisons of earthquake recurrence relationships on both the wasatch and san andreas faults based on historical seismicity data and geologic data show that a linear constant b value extrapolation of the cumulative recurrence curve from the smaller magnitudes leads to gross underestimates of the frequency of occurrence of the large or characteristic earthquakes only by assuming a low b value in the moderate magnitude range can the seismicity data on small earthquakes be reconciled with geologic data on large earthquakes the characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as well

modeling finite fault radiation from the ωn spectrum the high frequency seismic field near the epicenter of a large earth quake is modeled by subdividing the fault plane into subelements and summing their contributions at the observation point each element is treated as a point source with an o92 spectral shape where co is the angular frequency ground motion contributions from the subsources are calculated using a stochastic model attenuation is based on simple geometric spreading in a whole space coupled with regional anelastic atten uation q operator the form of the co n spectrum with natural n follows from point shear dislocation theory with an appropriately chosen slip time function the seismic moment and comer frequency are the two parameters defining the point source spectrum and must be linked to the subfanlt size to make the method complete two coefficients aa and k provide this link assigning a moment to a subfault of specified size introduces the stress parameter ao the relationship between comer frequency dislocation growth rate and fault size is established through the coefficient k which is inherently nonunique these two parameters control the number of subsources and the ampli tudes of high frequency radiation respectively derivation of the model from shear dislocation theory reveals the unavoidable uncertainty in assigning ogn spectrum to faults with finite size this uncertainty can only be reduced through empirical vali dation the method is verified by simulating data recorded on rock sites near epicenters of the m8 0 1985 michoacan mexico the m8 0 1985 valparaiso chile and the m5 8 1988 saguenay qurbec earthquakes each of these events is among the largest for which strong motion records are available in their respective tectonic environ ments the simulations for the first two earthquakes are compared to the more de tailed modeling of somerville et al 1991 which employs an empirical source function and represents the effects of crustal structure using the theoretical impulse response both methods predict the observations accurately on average the precision of the methods is also approximately equal the predicted acceleration amplitudes in our model are generally within 15 of observations an unexpected result of this study is that a single value of a parameter k provides a good fit to the data at high frequencies for all three earthquakes despite their different tectonic environments this suggests a simplicity in the modeling of source processes that was unanticipated

coda q estimates in the hong kong region abstract complementing a series of recent seismic hazard studies for hong kong we have estimated the q factor using 25 local earthquakes within 200 km of hong kong digitally recorded from january 1998 to july 2000 by eight short period stations of the hong kong observatory seismic monitoring network by analyzing the coda wave at frequencies 2 20 hz we obtained a q f relation of q 256 f 0 7 the values of q 0 q at 1 hz determined for three distance ranges r are 224 for r 50 km 342 for 50 r r 200 km the results are consistent with the spatial variations of the q factor in the wider region of south china the results fill an important gap in knowledge about the q factor and associated crustal attenuation conditions in the pearl river delta region including hong kong and provide useful insight into the influence of epicentral distance range in coda q measurements allowing better understanding of the degree of complexity in the crustal structure of the region

the geology of hong kong the eight papers included in this thematic set were presented at a meeting on the geology of hong kong held at the university of hong kong on 22 january 1997 the meeting reviewed the accomplishments of the hong kong geological survey and its co workers since it was founded fifteen years ago and coincided with the publication of the final geological memoir of the current series that describes the 1 20 000 scale geological maps of hong kong the meeting also formed part of the 20th anniversary celebrations of the establishment of the geotechnical engi neering office of the hong kong government a total of 112 registrants from consultant companies academic institutions researchers from china and several government departments attended the meeting in addition 40 students from the newly established department of earth sciences of hong kong university were present hong kong is one of the world s major urban communities with a population of over six million and in common with most of eastern asia is expanding rapidly however development is hindered by the rugged terrain and steep sided islands and engineers are tackling some of the world s largest and technically most challenging civil engineering projects this meeting highlighted the need for systematic and accurate geological information and the importance of understanding geological processes it brought together geologists geotechnical engineers and engineering geologists with the common objective to sustain the effective and safe development of hong kong the meeting was opened by the secretary for works h s kwong who described the significance of the

ground motions at memphis and st louis from m 7 5 8 0 earthquakes in the new madrid seismic zone the new madrid seismic zone is the most important regional seismic hazard in middle america having produced several very large earthquakes in historic and geologic time in this study we simulate time histories in memphis tennessee and st louis missouri for m 7 5 and m 8 0 earthquakes along two faults in the new madrid seismic zone simulations are based on a well established and calibrated finite fault simulation program finsim which has been shown to reproduce ground motions for earthquakes of m 4 8 in eastern and western north america beresnev and atkinson 2001a simulations are made for representative soil profiles for each city as well as for reference bedrock conditions at the base of the soil profile the effect of nonlinearity on soil amplification is considered for the soil sites uncertainty in the results is considered by modeling a wide range of alternative scenarios representing the major uncertainties in input parameters the total uncertainty in ground motions response spectra is about a factor of 2 results are most sensitive to magnitude hypocenter location directivity effects and maximum slip velocity the resulting time histories and spectra for all modeled scenarios are available as an electronic supplement to this article results are validated to the extent possible using the modified mercalli intensity mmi observations from the 1811 1812 earthquakes the simulated motions are consistent with mmi observations at st louis and memphis it is not possible to distinguish based on the mmi observations which of the m 7 5 or m 8 0 scenarios are most likely however we conclude that the most extreme scenarios such as m 8 0 with high slip velocity or large directivity effects are not likely because they would produce higher mmi values than those that were observed online material time histories and spectra for modeled scenarios

a two dimensional coupled ice ocean model of the bering sea marginal ice zone a two dimensional coupled ice ocean model has been formulated and applied to the wintertime bering sea marginal ice zone the oceanic component is a multilevel model that incorporates second moment closure for turbulent mixing in the water column the ice cover is modeled as a viscous plastic continuum melting at the ice ocean interface is computed using well known lawof the wall concepts in a turbulent boundary layer with particular attention to the disparate momentum and scalar transfer resistance coefficients over rough walls the thermodynamic and dynamical interactions between the ocean and the ice cover and the energy balances at the air ice and air sea interfaces are modeled according to the companion paper mellor and kantha this issue the model incorporates barotropic tides both diurnal and semidiurnal for application to the bering shelf double diffusive fluxes across the interface between the colder fresher layer beneath the melting ice and the warmer more saline water underneath are prescribed from laboratory data on double diffusive convection during winter sea ice in the central bering sea is transported toward the shelf break by off ice winds where it encounters northward flowing warmer north pacific waters and melts it is this situation to which the two dimensional model has been applied by neglecting all variations in the along ice edge direction the water conditions downstream of the ice edge the ice conditions upstream and the wind stress are the primary inputs to the model the model simulates transition from ice covered to open ocean conditions and the associated ice edge front and the two layer circulation underneath the ice cover sensitivity studies indicate that the density structure and the circulation beneath the ice and the position of the ice edge are rather sensitive to the parameters affecting the dynamics and the thermodynamics of the coupled ice ocean system even small changes in the relevant parameters can cause a substantial retreat or advance of the ice edge which may help explain why marginal ice zones are such dynamically active regions

organo metallic complexes in an andosol a comparative study with a cambisol and podzol current soil forming processes were studied in a nonallophanic andosol from the vosges mountains north eastern france for this purpose we conducted comparative studies on the organo metallic fraction dynamics of selected profiles of an andosol and other typical soils from this region cambisol and podzol these soils are derived from old volcanic rocks under mesic soil temperature and udic soil moisture regimes the andosol profile displayed the characteristics of nonallophanic andosols large accumulation of humus active al mostly complexed with humus and low ph special attention was given to physical and microbial stability of these organo metallic associations respectively by disaggregation tests and incubation experiments the results indicated that these associations showed a strong resistance against disaggregation by water and against biodegradation moreover the very low concentration of doc al and fe in soil solutions collected by zero tension lysimeters coupled with very low amounts of water dispersed clays obtained after dispersion tests suggested that no significant translocations of these components occurred in this andosol profile low mobility together with a strong resistance against mineralization may account for the large accumulation of carbon in this andosol

forcing of oceanic heat anomalies by air sea interactions in the nordic seas area 1 hydrographic data and atmospheric reanalysis from 1982 to 2005 are used to show a strong link of the atlantic water temperature awt anomalies observed in the transition zone between the norwegian atlantic current and the west spitsbergen current in summer to the surface heat flux shf anomalies observed over the barents sea open water in the preceding late winter a mechanism proposed for this link is formation of ocean temperature anomalies in a deep mixed layer and their subsequent westward export by a branch of atlantic water recirculating in the western barents sea the shf anomalies over the barents sea are due to advection of temperature and humidity by anomalous winds across the arctic ice edge and do not strongly depend on the north atlantic oscillation nao correlations of up to about 0 9 between the awt anomalies and indices of atmospheric variability over the barents sea open prospects for seasonal awt predictability it is also shown that the wind forcing responsible for positive awt anomalies is involved in a cyclonic perturbation of the atmospheric circulation over the nordic seas this perturbation generates through influence on the sea ice distribution a lobe of shf anomalies in the marginal ice zone miz on the eastern barents sea and western greenland sea sides of the nordic seas which has the opposite sign to the open water lobe in contrast to the barents sea miz the diabatic heating of the atmosphere by upward shf anomalies in the greenland sea miz competes with cold advection