a referenced empirical ground motion model for arias intensity and cumulative absolute velocity based on the nga east databasea referenced empirical ground motion model for arias intensity and cumulative absolute velocity based on the nga east database

predictive model for seismic sliding displacement of slopes based on a coupled stick slip rotation approach abstract this paper represents a predictive model for the earthquake induced displacement of slopes using a coupled stick slip rotation approach recently proposed by the authors in a preceding paper a collection of 1363 strong motion records associated with 25 worldwide earthquakes was used to generate the model on the basis of results of sliding block analyses the proposed model predicts sliding displacement in terms of yield acceleration coefficient ratio ky kmax period ratio ts tm and slip length l the regression analysis indicates that dividing the results into the smaller intervals of period ratio can provide a noticeable higher degree of accuracy probable bias of the residuals versus the input variables is examined in detail predictions of the developed equation are compared with some available sliding block equations which similarly assumed a flexible sliding mass the proposed model can be simply used to estimate landslide hazard in seismic prone regions

persistent upwelling and front over the sulu ridge and their variations the persistent upwelling and front isolated over the sulu ridge are newly detected by a suite of satellite measurements and confirmed by historical cruise observations a three dimensional tide circulation coupled model is employed to investigate the dynamic mechanisms the intense vertical velocity shear induced by the vigorous internal tidal mixing is identified as the vital dynamic factor to trigger the upwelling and nutrient pumping through the strong tide topography interactions satellite observations indicate that the pronounced surface cooling and phytoplankton bloom are isolated over the sulu ridge throughout the year the steady front characterizes 10 20 km width and strength over 0 3 degrees c km near the southern edge the feature is further confirmed by the numerical simulation and in situ hydrological observation modeling experiment suggests that a quasi symmetrical vertical circulation bifurcation across the sulu ridge due to the asymmetry of tidal currents is the main mechanism to maintain the persistent upwelling and front moreover the local wind forcing plays an important regulating role in the seasonal and interannual variations the surface cooling and thermal front intensity reach the maximum in winter under the forcing of strong northeasterly monsoons due to prolonged el nino southern oscillation enso effects the surface cooling was significantly weakened during 1998 and 2010 summer further analysis indicates the fact that the southwesterly monsoon is weakened dramatically as part of the anticyclonic atmospheric circulation anomalies over the northwest pacific the latter results from the significant influence of tropical indian ocean capacitor effect associated with el nino southern oscillation

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

new empirical relationships between arias intensity and peak ground acceleration abstract arias intensity i a and peak ground acceleration pga have been widely used as measures of the intensity of strong ground motions this study employs a large set of data consisting of 7034 horizontal and 3474 vertical strong motion records from 173 worldwide earthquakes m w 4 3 7 9 to refine the relationship between i a and pga and investigates its potential dependence on variables such as earthquake magnitude m w local site condition v s 30 focal mechanism and fault distance the dataset from the 2011 m w 9 0 tohoku earthquake and the 2013 m w 6 8 lushan earthquake is used to demonstrate the usability and necessity of our models the results reveal that the logarithm of i a increases linearly with the increase of the logarithm of pga and m w and the decrease of the logarithm of v s 30 and this kind of correlation is not significantly affected by focal mechanism and fault distance new global empirical relationships for both horizontal and vertical components are developed to estimate i a as a function of pga m w and v s 30 the resulting correlation equations presented in this article represent a significant advancement by incorporating such important features as magnitude and v s 30 and enable an improved way of estimating i a from pga online material table of earthquake parameters

nonlinear internal wave evolution in the sulu sea abstract this paper presents an analytical investigation of nonlinear internal wave evolution in the sulu sea a solitary wave theory that describes tie evolution of internal solitons has been developed and expanded to include effects of vertical shear variable bottom topography radial spreading and dissipation a numerical parametric study has been performed in order to understand the relative importance of radial spreading and dissipation effects on soliton decay across the sulu sea using sulu sea environmental and initial data the numerical simulations reproduce reasonably well the measurements at the downstream mooring from the sulu sea internal soliton experiment comparison of simulations with data on the evolution of lead wave amplitude across the sulu sea indicates that the variable depth effect is appreciable and the radial spreading and dissipation effects are very significant the effects of the earth s rotation vertical shear variable bottom topography radial spreading and dissipation

hybrid empirical ground motion prediction equations for eastern north america using nga models and updated seismological parameters in the field of earthquake engineering ground motion prediction models are frequently used to estimate the peak ground acceleration pga and the pseudos pectral acceleration psa in regions of the world where ground motion recordings are plentiful such as western north america wna the ground motion prediction equations are obtained using empirical methods in other regions such as eastern north america ena with insufficient ground motion data alternative methods must be used to develop ground motion prediction equations gmpes the hybrid empiri cal method is one such method used to develop ground motion prediction equations in areas with sparse ground motions this method employs the stochastic simulation method to adjust empirical gmpes developed for a region with abundant strong motion recordings in order to estimate strong motion parameters in a region with a sparse database the adjustments take into account differences in the earthquake source wave propagation and site response characteristics between the two regions in this study a hybrid empirical method is used to develop a new gmpe for ena using five new ground motion prediction models developed by the pacific earthquake engineering research center peer for wna a new ena gmpe is derived for a magnitude range of 5 to 8 and closest distances to the fault rupture up to 1000 km ground motion prediction equations are developed for the response spectra pseudoacceleration 5 damped and the pga for hard rock sites in ena the resulting ground motion prediction model developed in this study is compared with two ena ground motion models used in the 2008 national seismic hazard maps as well as with available observed data for ena

once again once again tidal friction topex poseidon t p altimetry has reopened the problem of how tidal dissipation is to be allocated there is now general agreement of a m2 dissipation by 2 5 terawatts 1 tw 1012 w based on four quite separate astronomic observational programs allowing for the bodily tide dissipation of 0 1 tw leaves 2 4 tw for ocean dissipation the traditional disposal sites since jeffreys 1920 have been in the turbulent bottom boundary layer bbl of marginal seas and the modern estimate of about 2 1 tw is in this tradition but the distribution among the shallow seas has changed radically from time to time independent estimates of energy flux into the marginal seas are not in good agreement with the bbl estimates t p altimetry has contributed to the tidal problem in two important ways the assimilation of global altimetry into laplace tidal solutions has led to accurate representations of the global tides as evidenced by the very close agreement between the astronomic measurements and the computed 2 4 tw working of the moon on the global ocean second the detection by ray and mitchum 1996 of small surface manifestation of internal tides radiating away from the hawaiian chain has led to global estimates of 0 2 to 0 4 tw of conversion of surface tides to internal tides measurements of ocean microstructure yields 0 2 tw of global dissipation by pelagic turbulence away from topography we propose that pelagic turbulence is maintained by topographic scattering of barotropic into baroclinic tidal energy via internal tides and internal waves previous estimates by baines 1974 baines 1982 of this conversion along 150 000 km of continental coastlines gave a negligible 0 02 tw evidently the important conversion takes place along mid ocean ridges the maintenance of the abyssal global stratification requires a much larger expenditure of power 2 tw versus 0 2 tw this is usually attributed to wind forcing if tidal power is to play a significant role here then the bbl estimates need to be reduced the challenge is to estimate dissipation from the energy flux divergence in the t p adjusted tidal models without prior assumptions concerning the dissipation processes

tracking oceanic nonlinear internal waves in the indonesian seas from geostationary orbit abstract nonlinear internal waves nliws in the ocean are observable from passive satellite radiometers the surface manifestations of these internally propagating waves are curvilinear bands demarcating relatively smooth and rough surface waters providing a means for their detection via observations of sunglint typical horizontal scales of nliws are such that traditionally only high resolution

integrating u th 14c and 210pb methods to produce a chronologically reliable isotope record for the belize river valley maya from a low uranium stalagmite social and environmental changes had great spatiotemporal variability in the maya lowlands during the classic and postclassic periods and stalagmites promise high resolution paleoclimate data that

reconstructing seawater column 90sr based upon 210pb 226ra disequilibrium dating of mollusk shells abstract the shells of marine and fresh water mollusks can serve as effective archives in retrieving information on natural and anthropogenic environmental changes the advantage of using bivalves is that they integrate water chemistry changes into their shells during their life span retrospective study of environmental changes and pollutants using bivalve shells requires precise determination of the time of incorporation into the abiotic environmental matrix here after age of the specimen for the first time a set of archived bivalve samples for which date of the death collection is known has been analyzed to establish the ages of mollusk shells using the 210 pb 226 ra disequilibrium method in addition sr and 90 sr were analysed the ages obtained using the 210 pb 226 ra disequilibrium dating method agrees well with the calendar years calculated from the date of death collection the ages obtained can be utilized to reconstruct the 90 sr levels in the water column at sites where the mollusk shells were collected

motions of gently sloping ground during earthquakes 1 during past earthquakes gently sloping ground surfaces have been observed to shift laterally over areas as large as a few square kilometers these permanent downward motions have been attributed to temporary and partial reductions in shear strength of soil deposits e g liquefaction static gravity forces and transient earthquake shakings these motions the amplitudes of which remain challenging to predict have been frequently modeled using newmark sliding blocks for ground that is statically stable and occasionally partially or completely loses its shear strength during earthquakes this paper investigates in more details the deformations of gently sloping ground that becomes temporarily unstable under the combined effects of gravitational forces and earthquake shakings using a physical model we propose two definitions of earthquake contributions to the displacement of gently sloping ground which may include or not the effects of initial velocity in both cases monte carlo simulations reveal that motions of gently sloping ground are influenced by pulses of earthquake ground velocity for a wide range of reduction in soil shear strength even for very severe loss of shear strength for practical purposes when large soil deposits become unstable during earthquakes the analysis concludes that the motions of gently sloping ground are likely influenced by earthquake ground velocity

ground motion prediction equations for eastern north america from a referenced empirical approach implications for epistemic uncertainty abstract i outline a referenced empirical approach to the development of ground motion prediction equations gmpes the technique is illustrated by using it to develop gmpes for eastern north america ena the approach combines the ena ground motion database with the empirical prediction equations of boore and atkinson 2008 for the reference region of western north america wna the referenced empirical approach provides gmpes for ena that are in agreement with regional ground motion observations while being constrained to follow the overall scaling behavior of ground motion that is observed in better instrumented active tectonic regions they are presented as an alternative to the commonly used stochastic ground motion relations for ena the motivation of the article is not to supplant stochastic gmpes but is rather to consider other approaches that might shed light on their epistemic uncertainty differences between the referenced empirical gmpes of this study and the stochastic gmpes of atkinson and boore 2006 along with inconsistencies between both of these studies and inferences based on intensity observations suggest that uncertainty in median enagmpes is about a factor of 1 5 2 for m 5 at distances from 10 to 70 km uncertainty is greater than a factor of 2 for large events m 7 at distances within 10 km of the source it may be that saturation effects not modeled in the stochastic predictions but inferred from observations in other regions cause overestimation of near source amplitudes from large events in atkinson and boore 2006 on the other hand these saturation effects cannot be directly verified in ena data differences in predictions according to the approach taken are also significant at distances from 40 to 150 km due to uncertainty in the shape of the attenuation function that will be realized in future earthquakes

assessment of liquefaction potential during earthquakes by arias intensity an arias intensity approach to assess the liquefaction potential of soil deposits during earthquakes is proposed using an energy based measure of the severity of earthquake shaking recorded on seismograms of the two horizontal components of ground motion values representing the severity of strong motion at depth in the soil column are associated with the liquefaction resistance of that layer as measured by in situ penetration testing spt cpt this association results in a magnitude independent boundary that envelopes initial liquefaction of soil in arias intensity normalized penetration resistance space the arias intensity approach is simple to apply and has proven to be highly reliable in assessing liquefaction potential the advantages of using arias intensity as a measure of earthquake shaking severity in liquefaction assessment are arias intensity is derived from integration of the entire seismogram wave form incorporating both the amplitude and duration elements of ground motion all frequen

stalagmite evidence from belize indicating significant droughts at the time of preclassic abandonment the maya hiatus and the classic maya collapse abstract paleoenvironmental data from a stalagmite from western belize provide a 3300 year record of droughts that impacted the maya civilization at least four times across a span of 1500 years and the most sustained period of drought coincided with the collapse of classic maya civilization the stalagmite which comes from macal chasm in the vaca plateau provides reliably dated reflectance color luminescence and c and o stable isotope records for the period from 1225 b c to the present the record thus encompasses the maya preclassic classic and postclassic periods the maya civilization peaked in population density and socioeconomic complexity during the classic period extending from a d 25 to 900 but it declined abruptly over the years from a d 750 and 900 the stalagmite record indicates that a series of droughts which collectively form the most prolonged dry interval in the 3300 year record lasted from a d 700 to 1135 and thus coincided with the collapse of the maya civilization in addition two earlier droughts evident in the stalagmite record coincided with the preclassic abandonment and the maya hiatus two earlier declines in maya civilization a drought in the mid 1400s recorded in post classic documents is also evident in the stalagmite record collectively these findings illustrate the dependence of mayan civilization on water supplies and the impact of declining water resources on a vibrant civilization

empirical stochastic ground motion prediction for eastern north america an alternative approach based on a hybrid empirical model is utilized to predict the ground motion relationship for eastern north america ena in this approach a stochastic model is first used to derive modification factors from the ground motions in western north america wna to the ground motions in ena the ground motion parameters are then estimated to develop an empirical attenuation relationship for ena using empirical ground motion relationships from wna w e develop an empirical stochastic source model for both regions to obtain ground mo tions at different magnitude distance range of interest at short distances r 30 km and large magnitudes mw 6 4 an equivalent point source model is carried out to consider the effect of finite fault modeling on the ground motion parameters source focal depth and brune stress drop are assumed to be magnitude dependent we choose three well defined empirical attenuation relationships for wna to com pare the empirical ground motion processes between the two regions a composite functional attenuation form is defined and in turn a nonlinear regression analysis is performed by using a genetic algorithm ga for a wide range of magnitudes and distances to develop an empirical attenuation relationship from the stochastic ground motion estimates in ena the empirical stochastic attenuation relationship for hor izontal peak ground acceleration and spectral acceleration are applicable to earth quakes of mw 5 0 8 2 at distances of up to 1000 km the resulting attenuation model developed in this study is compared with those used in the 2002 national seismic hazard maps derived in the 2003 electric power research institute studies and re corded in ena the comparison of the results to the other attenuation functions and the available ena data show a reasonable agreement for the ena ground motions

oceanic internal waves in the sulu celebes sea under sunglint and moonglint moonglint and sunglint satellite imagery acquired from moderate resolution imaging spectroradiometer modis and visible infrared imaging radiometer suite viirs satellite sensors were used to study the characteristics of internal waves iws and their relationship to tides and stratification in the sulu celebes sea tidally generated iws propagate northwestward and southeastward into the sulu and celebes seas showing a spring neap tidal cycle behavior with larger smaller iws occurring under spring neap tides respectively the length of iw crests their wavelength and phase speed derived from the sunglint moonglint image pairs were observed to decrease from spring to neap tides iws in the sulu celebes sea which are correlated with oceanic stratification display seasonal and regional fluctuations in the celebes sea iws were less frequently observed but propagated with faster phase speeds and larger scales compared to those in the sulu sea comparisons of stratification and barotropic tidal transport among the iws generation sites indicate that the shallowing maximum brunt vaisala frequency and strongest tidal transport around pearl bank are major factors contributing to greater iw activity compared to other generation sites iws generated near pangutaran island and pearl bank further merge into one dynamical system creating longer wave crests of 200 km that travel at faster phase speed sim 2 5 text m cdot text s 1 in the sulu sea this paper demonstrates a new application using a combination of sunglint moonglint imagery in tracking an important oceanic phenomenon

analyses of internal solitary waves generated at the columbia river plume front using sar imagery 1 internal solitons generated at the columbia river plume front during ebb tide are displayed on a synthetic aperture radar sar image taken on 26 july 2004 at 14 24 22 utc scale analyses suggest that these internal solitons belong to the finite depth category a theoretical model relating the radar backscatter cross section to dynamic parameters of internal solitons in the continuous stratification is developed using the model and background stratification data collected by the river influences on shelf ecosystem rise project in july 2004 we extract the soliton dynamic parameters of the half width amplitude phase speed and average energy flux per crest length along a typical section across the internal solitons the observed stratification is simulated by using a theoretical model parameterized by pycnocline depth thickness and maximum buoyancy frequency the half width amplitude phase speed and energy flux of the leading soliton at the section are 119 3 m 9 3 m 0 69 m s 1 and 417 4 w m 1 with the uncertainty ranges of 14 7 m 2 6 m 0 10 m s 1 and 281 6 w m 1 respectively sensitivity analyses reveal that the extraction of the soliton half width from the sar image is not affected by the stratification the amplitude is less influenced by the pycnocline thickness than the depth and is independent of the maximum buoyancy frequency

the coupling between harbor seiches at palawan island and sulu sea internal solitons abstract between 1989 and 1991 the authors made observations that confirm and elucidate the coupling between harbor seiches at puerto princesa on palawan island in the philippines and tide generated internal solitons in the sulu sea published tidal current predictions for basilan strait in the sulu archipeligo were used to produce an index to the daily ebb tidal flows near pearl bank where the solitons originate the coherence between predicted maximum ebb tidal current speed and observed seiche activity was 0 60 and the phase lag between the two quantities closely matched published estimates of the time required for solitons to cross the sulu sea arrival of the sulu sea waves immediately offshore of puerto princesa in the form of internal bores corresponded in time to the initiation of harbor seiche activity a more precise estimate of soliton travel time was determined from the time difference between predicted maximum ebb current and the initiation of seiche activity and it was found to have a remar

three dimensional nonhydrostatic numerical simulation of nonlinear internal wave generation and propagation in the south china sea 1 we present the results of three dimensional nonhydrostatic simulations of internal tides and waves in the south china sea scs using the suntans model model results accurately predict the observed wave arrival times at two mooring locations in the scs internal wave amplitudes are underpredicted which causes underprediction of internal wave speeds due to a lack of amplitude dispersion we show that the well known a and b waves arise from the steepening of semidiurnal internal tides that are generated due to strong barotropic flow over ridges in the luzon strait a wave generation is stronger in the southern portion of the luzon strait because diurnal internal tidal beams augment the amplitude of the semidiurnal a waves b wave generation is stronger in the northern portion where the distance between the eastern and western ridges is approximately equal to one internal tidal wavelength and leads to semidiurnal internal tidal resonance the orientation of the ridges produces large a waves that propagate into the northern portion of the western scs basin and stronger b waves that propagate into the southern portion when traced back in time along linear characteristics a waves consistently line up close to peak ebb eastward barotropic currents while b waves consistently line up with peak flood westward barotropic currents this reinforces the notion that the lee wave mechanism and associated hydraulic or nonlinear effects are weak as demonstrated by a simple linear model relating the amplitude of the simulated waves to the excursion parameter at the ridges

a nonlinear model of the shoaling and refraction of interfacial solitary waves in the ocean part i development of the model and investigations of the shoaling effect abstract oceanic internal waves are frequently observed to be of large amplitude and to exhibit significant wave front curvature as seen in synthetic aperture radar images the aim of this paper is to present a refraction model in two horizontal dimensions including moderate amplitude effects to model these common properties of internal waves the model incorporates second order nonlinearity and uses a ray method to allow arbitrary refraction for these preliminary investigations with the model a two layer ocean is assumed with an upper layer thickness of 50 m and a density difference across the layers of 0 5 kg m 3 an important aspect affecting the refraction of nonlinear waves is shoaling as the phase speed of a nonlinear wave depends on its amplitude in part i of this paper the development of the model is described and the shoaling phenomenon is investigated in detail the shoaling of interfacial internal solitary waves over both slowly varying and rapidly varying bathymetry is studied a wedg

biological and chemical characteristics of high chlorophyll low temperature water observed near the sulu archipelago abstract according to ocean color remote sensing data a low phytoplankton biomass exists in the central parts of the sulu and celebes seas whereas higher concentrations of chlorophyll a are observed in the waters near the sulu archipelago which separates these water bodies these high chlorophyll a waters have lower temperatures than those of surrounding waters indicating vertical mixing of nutrient rich subsurface water that is attributable to the topographical features of the sulu ridge differences in photosynthetic parameters primary productivity and the phytoplankton community structure between the high chlorophyll area near the sulu archipelago and the oligotrophic basin area in the philippine sulu and celebes seas were investigated in november 2002 during the r v hakuho maru kh 02 4 cruise entrainment of subsurface water and vertical mixing by intense tidal flow from the sulu archipelago to the celebes sea created a low temperature high nutrient condition at the southeastern edge of the sulu ridge chlorophyll a concentrations greater than 2 g l 1 were observed at stations 5 15 km offshore at the edge of the sulu ridge this high chlorophyll tongue in the celebes sea showed high primary productivity it was 1 6 18 times higher than those measured in oligotrophic central basin regions of the philippine sulu and celebes seas microscopic observation of these high chlorophyll waters showed the dominance of chain forming large centric diatoms extension of high chlorophyll waters was not observed at the sulu sea side where the surface water salinity was lower than in the celebes sea and consequently prevented intrusion of the celebes sea water into the surface layer occasional extensions of productive chlorophyll rich surface water from the archipelagic zone to the surrounding basin area seems to be an important factor causing spatiotemporal variability in the phytoplankton biomass in the southern sulu sea and the western celebes sea

the δ18o and δ13c records in an aragonite stalagmite from furong cave chongqing china a 2000 year record of monsoonal climate abstract a 7 cm long aragonite stalagmite fr0510 1 from furong cave chongqing was dated by 210pb and 230th methods revealing a 2000 year record of climate history under the influence of the east asian monsoon the fr0510 1 record resembles dongge cave da record on 10 100 year scales but quite different from the wanxiang cave wx42b record indicating that while stalagmite 18o record represents local regional moisture change spatial variability of the monsoonal rainfall over eastern china must take into account during the past 2000 years climate in chongqing was relatively wet in the intervals of 50 bc ad 250 ad 1150 1450 and ad 1600 1950 and relatively dry during the periods of ad 250 1150 and ad 1450 1600 dry conditions were prevailing over the medieval warm period whereas wet climates were dominant during the most time of the little ice age in chongqing area

testing theoretically predicted stalagmite growth rate with recent annually laminated samples implications for past stalagmite deposition annually laminated stalagmites deposited over the last 30 160 years are analysed to determine their growth rate three natural and artificial cave sites in england france and belgium were chosen for their wide range of variability in growth rate determining variables and multiple samples were taken from each site the annual nature of laminae deposition within the stalagmite calcite was confirmed by comparison to the date of cave void opening 14c analyses or by using dated event horizons measured stalagmite growth rate was determined from annual laminae thickness measurements and compared to that theoretically predicted from the chemical kinetics of the calcite precipitation reaction a good agreement is observed between empirical observations and theoretical predictions although two complicating factors variations in calcite porosity and seasonal cessation of the water supply to the samples both affect the growth rate implications for the extraction of palaeoclimate information from stalagmite growth rate are discussed

natural radionuclide mobility and its influence on u th pb dating of secondary minerals from the unsaturated zone at yucca mountain nevada abstract extreme u and pb isotope variations produced by disequilibrium in decay chains of 238u and 232th are found in calcite opal chalcedony and mn oxides occurring as secondary mineral coatings in the unsaturated zone at yucca mountain nevada these very slowly growing minerals mm my 1 contain excess 206pb and 208pb formed from excesses of intermediate daughter isotopes and cannot be used as reliable 206pb 238u geochronometers the presence of excess intermediate daughter isotopes does not appreciably affect 207pb 235u ages of u enriched opal chalcedony which are interpreted as mineral formation ages opal and calcite from outer younger portions of coatings have 230th u ages from 94 6 3 7 to 361 3 9 8 ka and initial 234u 238u activity ratios ar from 4 351 0 070 to 7 02 0 12 which indicate 234u enrichment from percolating water present day 234u 238u ar is 1 in opal chalcedony from older portions of the coatings the 207pb 235u ages of opal chalcedony samples range from 0 1329 0 0080 to 9 10 0 21 ma increase with microstratigraphic depth and define slow long term average growth rates of about 1 2 2 0 mm my 1 in good agreement with previous results measured 234u 238u ar in mn oxides which pre date the oldest calcite and opal chalcedony range from 0 939 0 006 to 2 091 0 006 and are 1 in most samples the range of 87sr 86sr ratios 0 71156 0 71280 in mn oxides overlaps that in the late calcite these data indicate that mn oxides exchange u and sr with percolating water and cannot be used as a reliable dating tool in the u poor calcite samples measured 206pb 207pb ratios have a wide range do not correlate with ba concentration as would be expected if excess ra was present and reach a value of about 1400 the highest ever reported for natural pb calcite intergrown with opal contains excesses of both 206pb and 207pb derived from rn diffusion and from direct recoil from u rich opal calcite from coatings devoid of opal chalcedony contains 206pb and 208pb excesses but no appreciable 207pb excesses observed pb isotope anomalies in calcite are explained by rn produced excess pb the rn emanation may strongly affect 206pb 238u ages of slow growing u poor calcite but should be negligible for dating fast growing u enriched speleothem calcite

rainfall and hydrological controls on speleothem geochemistry during climatic events droughts and typhoons an example from seopdong cave republic of korea abstract a five year old 20 cm long soda straw sd 1 was analyzed geochemically to delineate the relationship between the geochemical record and climatic behavior the growing tip of the soda straw was marked on july 18 1999 and the sample was collected on july 16 2004 thus the growth period of this speleothem is well constrained during the five years the soda straw grew about 20 cm a mean growth rate of about 4 cm year fast growth rate of this speleothem enabled not only to understand seasonal variations of geochemical data but also to compare these data directly with outside climatic variations near the cave 210 pb ex excess or unsupported 210 pb results suggest that the overall pattern of 210 pb ex changes as well as the frequency and relative intensity of their peaks show a strikingly similar pattern to that of the amounts of precipitation in the study area this suggests that 210 pb ex was transported into the cave with infiltrating rainwater mostly during rainy summers because 210 pb ex is a particle reactive element controlling detailed growth rates by the 210 pb ex fluctuations it can be noticed that 18 o compositions vary very little in spite of significant droughts and typhoon events whereas 13 c values clearly display impacts of a severe drought from 2000 to 2001 the sr ca ba ca u ca and mn ca ratios coincide with the 13 c trends and show anomalies during the drought period these coeval trends strongly indicate that hydraulic factors in vadose zone that were directly controlled by the amount of rainfall influenced on the geochemical imprints of the sd 1 this study illustrates the behavior of an atmospheric radionuclide 210 pb ex the o and c stable isotopes and trace elements in calcite speleothems and furthermore implies that they can be used to detect short term climatic behavior including climatic extreme events as well as the long term climatic fluctuations in the past

internal solitary waves in the warm pool of the western equatorial pacific abstract during the spring tides of late november 1992 early january and early february 1993 solitary internal wave packets were observed at 2 s 156 15 e in the western equatorial pacific apparently generated in the nuguria island group 3 s 153 e the waves propagate northeastward at 2 4 2 8 m s 1 appearing in fixed phase with the underlying semidiurnal baroclinic tide the initial solitary wave crests have downward displacements in excess of 60 m and peak velocities greater than 80 cm s 1 groups of 1 3 crests are observed with vertical structure resembling a first mode internal wave and horizontal variability consistent with third order comb kdv solitons many of the packets exhibit an overall organization reminiscent of undular bores this borelike behavior is confined primarily to the upper 70 m not sharing the mode one dependency of the crests the solitons displace the ambient equatorial currents including the equatorial undercurrent both vertically 80 m and laterally 1 2 km with l

combination of satellite observations and machine learning method for internal wave forecast in the sulu and celebes seas internal waves iws observed in the world oceans have significant impacts on ocean engineering and environments in this study we collected satellite images from moderate resolution imaging spectroradiometer and visible infrared imaging radiometer suite sensors in the sulu celebes sea from 2016 to 2019 to understand the iw generation and propagation satellite observations show a coherent iw phase difference in both seas indicating that the iws are alternatively generated when the tidal currents oscillate back and forth in the sulu archipelago which separates two seas a new generation site is found for occasionally observed long iws in the eastern sulu sea to understand the iw propagation characteristics we developed a machine learning based forecast model we trained the model with both iw wave crest curves extracted from satellite images and published climatological ocean temperature salinity profiles since many satellite images contain iw packets generated at two or three tidal cycles we can validate the model performance by matching the model prediction after one or two tidal cycles with the second or third wave crests in satellite images three factors are adopted to evaluate the forecast results the root mean square error rmse the frechet distance fd and the correlation coefficient cc the forecast model has an average error with an rmse of 12 92 km an fd of 18 73 km and a cc of 0 98 analysis shows that a smaller time step is preferred in regions where the water depth changes significantly comparison with the korteweg de vries equation solutions shows that the developed forecast model is more robust when errors introduced to the model inputs

seismic triggering of catastrophic failures on shear surfaces in saturated cohesionless soils this paper is concerned with an analysis of the seismic performance of infinite slopes in undrained conditions the material assumed on the sliding surface is a loose saturated sand susceptible to a gradual loss in undrained shear strength after failure with the progress of unidirectional shear displacement the undrained monotonic and cyclic shear behavior of this sand was investigated through an experimental study based on ring shear tests with initial stresses corresponding to the static conditions on the sliding surface of the analyzed slopes these tests provide the experimental framework for a modified sliding block method to estimate the earthquake induced undrained shear displacements for conditions of no shear stress reversals on the sliding surface the proposed estimation procedure incorporates the shearing resistance obtained from undrained monotonic ring shear tests to approximate the undrained yield resistance at a certain displacement during an earthquake the term catastrophic failure is

a nonlinear model of internal tide transformation on the australian north west shelf a numerical solution to the generalized korteweg de vries k dv equation including horizontal variability and dissipation is used to model the evolution of an initially sinusoidal long internal wave representing an internal tide the model shows the development of the waveform to the formation of shocks and solitons as it propagates shoreward over the continental slope and shelf the model is run using observed hydrographic conditions from the australian north west shelf and results are compared to current meter and thermistor observations from the shelf break region it is found from observations that the coefficient of nonlinearity in the k dv equation changes sign from negative in deep water to positive in shallow water and this plays a major role in determining the form of the internal tide transformation on the shelf there is strong temporal variability in the nonlinear coefficient due to both background shear flow and the large amplitude of the internal tide which distorts the density profile over a wave period both the model and observations show the formation of an initial shock on the leading face of the internal tide in shallow water the change in sign of the coefficient of nonlinearity causes the shock to evolve into a tail of short period sinusoidal waves after further propagation a second shock forms on the back face of the wave followed by a packet of solitons the inclusion of bottom friction in the model is investigated along with the dependance on initial wave amplitude and variability in the coefficients of nonlinearity and dispersion friction is found to be important in limiting the amplitudes of the evolving waves

analysis of nonlinear internal waves in the new york bight this paper presents the results on internal wave analysis of the current meter mooring data in the new york bight from the sar internal wave signature experiment sarsex selective sets of current and temperature measurements are analyzed for a parametric study of internal wave characteristics and shear effects on wave parameters are studied based on the limited data from moorings the solitary wave theory has been extended for the wave evolution on a continental shelf by including dissipation and shoaling effects a series of numerical simulations are performed to demonstrate the relative importance of dissipation and shoaling effects from an observed initial wave packet at the upstream mooring the numerical evolution simulation compares reasonably well with the measurements at the distant mooring for the leading two large solitons

spatial variability and attenuation of arias intensity during the 1999 chi chi mw 7 6 earthquake taiwan arias intensity is a measure of earthquake intensity that captures the potential destructiveness of an earthquake using the strong ground motion records of the m w 7 6 chi chi earthquake taiwan we analyze the spatial distribution of the vertical horizontal fault parallel and fault normal components of the arias intensity we investigate the effects of the hanging wall and footwall on ground motions and develop a relationship between arias intensity and peak ground acceleration pga incorporating the influence of local site conditions we also evaluate the applicability of some widely used arias intensity attenuation relationships by comparing the observed values with empirical estimates our results show the vertical arias intensity is generally lower than the horizontal component with nearly 90 of the vertical to horizontal ratios between 0 1 and 0 6 during this typical reverse mechanism earthquake the fault normal component of the arias intensity is approximately 20 higher than the fault parallel component for sites within 40 km of the fault arias intensities on the hanging wall are systematically higher than those on the footwall indicating clear hanging wall effects site conditions influence the correlation between arias intensity and pga arias intensity shows a good correlation with pga and v s 30 arias intensity increases with increasing pga and decreasing v s 30 the arias intensities observed within 40 km of site class c locations and within 80 km of site class d locations are generally lower than the mean estimates from empirical predictions in contrast at distances of 80 km from site class d locations the observed arias intensities are much larger than the empirical predictions as a result of site amplification considering the variability of ground motion between earthquakes the attenuation model of travasarou et al 2003 model 4 of stafford et al 2009 and the model of lee et al 2012 provide a good fit with observations from the chi chi earthquake online material table of station coordinates fault distances footwall hanging wall indicator site classes v s 30 and measured arias intensities

modifications to existing ground motion prediction equations in light of new data we compare our recent ground motion prediction equations gmpes for western north america wna boore and atkinson 2008 ba08 and eastern north america ena atkinson and boore 2006 ab06 atkinson 2008 a08 to newly available ground motion data based on these comparisons we suggest revisions to our gmpes for both wna and ena the revisions for wna affect only those events with m 5 75 while those for ena affect all magnitudes these are simple modi fications to the existing gmpes that bring them into significantly better agreement with data the wealth of new data clearly demonstrates that these modifications are warranted we therefore recommend the use of the updated equations for seismic hazard analyses and other applications more detailed studies are under way by many investigators including ourselves to develop a new generation of ground motion models in both wna and ena from scratch through a comprehensive reevaluation of source path site and modeling issues in time those more complete models will replace those proposed in this study however as the new models will be several years in development we recommend using the modified models proposed herein labeled ba08 for wna ab06 for ena and a08 for ena to replace a08 as interim updates to our existing models the proposed models are in demonstrable agreement with a rich database of ground motions for moderate magnitude earthquakes in both wna and ena and are constrained at larger magnitudes by the ba08 magnitude and distance scaling

regression models for estimating coseismic landslide displacement newmark s sliding block model is widely used to estimate coseismic slope performance early efforts to develop simple regression models to estimate newmark displacement were based on analysis of the small number of strong motion records then available the current availability of a much larger set of strong motion records dictates that these regression equations be updated regression equations were generated using data derived from a collection of 2270 strong motion records from 30 worldwide earthquakes the regression equations predict newmark displacement in terms of 1 critical acceleration ratio 2 critical acceleration ratio and earthquake magnitude 3 arias intensity and critical acceleration and 4 arias intensity and critical acceleration ratio these equations are well constrained and fit the data well 71 br 2 b88 but they have standard deviations of about 0 5 log units such that the range defined by the mean one standard deviation spans about an order of magnitude these regression models therefore are not recommended for use in site specific design but rather for regional scale seismic landslide hazard mapping or for rapid preliminary screening of sites 2007 elsevier b v all rights reserved

ground motion amplitudes for earthquakes in puerto rico we explore ground motion amplitudes for earthquakes in puerto rico using the referenced empirical approach the technique is based on the use of residual analysis to model discrepancies between ground motion observations for puerto rico and a reference ground motion prediction equation gmpe the refer ence gmpe is that of boore and atkinson 2008 for shallow crustal earthquakes in active tectonic regions as modified by atkinson and boore 2011 to improve the fit for small to moderate events amplitudes are examined for both shallow depth 34 km and deep 35 200 km earthquakes in puerto rico overall we conclude that ground motions in puerto rico are consistent in attenuation rates with those in other active regions for shallow events amplitude levels appear to be lower than those predicted by boore and atkinson 2008 but the discrepancy is magnitude dependent decreasing to a near zero bias near m 6 we thus postulate that amplitude levels may be considered equivalent for the magnitude distance range of engineering interest allowing gmpes for other active regions to be used for puerto rico furthermore deeper events have amplitudes that also appear consistent with typical gmpes for shallow events if the greater distance of the events due to their depth is considered

applicability of the nga west2 site effects model for central and eastern north america abstract we examine the applicability of the next generation attenuation west2 nga west2 site effects model seyhan and stewart 2014 which is a v s 30 based time averaged shear wave velocity in the upper 30 m model to sites in central and eastern north america cena using the nga east ground motion database we determine residual site terms by comparing the observed cena ground motion amplitudes adjusted to b c site condition v s 30 760 m s using the western site effects model to the corresponding predicted amplitudes of a cena ground motion prediction equation for b c site condition yenier and atkinson 2015 the cena prediction model used the same western site model to level the database before model development thus residual trends reveal inadequacies of the western site effects model when applied to cena ground motions plotting the residual site terms versus their corresponding site fundamental frequencies f peak reveals significant f peak dependent trends at all frequencies average residual site terms for cena sites after the western site amplifications have been removed can be as large as 0 45 in log10 units 2 8 in nonlog units around f f peak correlating the site terms with western site effects predictions reveals that at f v s 30 in a manner that is similar to the way they behave in the nga west2 database however at higher frequencies the correlation of site amplification with v s 30 decreases markedly in cena in contrast the horizontal to vertical h v component spectral ratio as obtained from the nga east ground motion data is a good predictor of the observed f peak dependent site terms suggesting that h v spectral ratio is a more reliable predictor of site amplification for the recording stations of the nga east database the results of this study demonstrate the importance of a well calibrated regional site effects model for cena and the importance of f peak as a site indicator

a new analytical model for internal solitons in the ocean abstract a new model for tidally generated internal solitons in the ocean is advanced based on a little known asymptotic analytical solution to the weakly nonlinear korteweg de vries equation the solution has many of the properties observed in oceanic internal solitary waves solitons it has been adapted to simulate the dynamics of stratified fluid flow driven by tidal forcing at continental shelves and sills and the adaptation describes the canonical behavior of such solitary wave trains it is shown that the solitons are positioned at the leading edge of an internal tidal bore on the shelf and that the distance between successive packets of solitons constitutes the internal tidal wavelength a future paper will apply the model to field observations from four geographical regions

seismic displacement of gently sloping coastal and marine sediment under multidirectional earthquake loading abstract gentle sediment laden slopes are typical of the onshore coastal zone and offshore continental shelf and slope coastal sediment are commonly young weakly consolidated materials that are well stratified have low strength and can mobilize shear displacements at low levels of stress seismically driven plastic displacements of these sediment pose a hazard to coastal cities buried onshore utilities and offshore infrastructure like harbor protection and outfalls one dimensional rigid downslope directed newmark sliding block analyses have been used to predict earthquake deformations generally on steeper slopes that are modeled as frictional materials this study probes the effect of multidirectional earthquake motions on inertial displacements of gently sloping ground of the coastal and offshore condition where soft compliant soil is expected toward that objective this investigation seeks to understand the effect on newmark type displacements of 1 multidirectional earthquake shaking and 2 soil compliance in order to model multidirectional effects the earthquake motions are rotated into the local slope strike and dip components on gently sloping ground including the strike component of motion always results in a larger and more accurate shear stress vector strike motions are found to contribute to downslope deformations on any declivity compliant response of the soil mass also influences the plastic displacements the magnitude of seismic displacements can be estimated with a simplified model using only the estimated soil yield acceleration ky and the peak ground velocity vmax of the earthquake motions compliance effects can be effectively mapped using the concept of plastic displacement response spectra pdrs

a preliminary probabilistic seismic hazard assessment in terms of arias intensity in southeastern spain financiado por el grupo de investigacion peligrosidad sismica y microzonificacion de la junta de andalucia rnm 0217 y por el proyecto de la cicyt ries ctidib 2002 177

high resolution δ18o and δ13c records during the past 65 ka from fengyu cave in guilin variation of monsoonal climates in south china abstract the 18 o and 13 c records of a 230 th u dated 2 2 m long stalagmite from fengyu cave in south china provide a continuous decadal resolution with 3698 measurements proxy for regional climatic and environmental conditions during 4 65 ka this single stalagmite reveals all heinrich cold events most dansgaard oeschger warm events deglaciation and holocene optimum generally supporting the hulu and dongge records on 5000 10000 year time scales the 18 o and 13 c variations show strongly positive correlations r 0 7 reflecting that a common climatic factor controls both 18 o and 13 c of f 1 the comparison of the speleothem ice core insolation and marine records reveals strong linkages between n atlantic temperature and the asian summer monsoon over most of the study period however there are some regional discrepancies between the stalagmite 18 o records following the deglaciation although the nh summer insolation provides the major forcing on asian monsoon variability over orbital time scales the weakest summer monsoon intensity during the last glacial occurred ca 16 ka corresponding to the heinrich event 1 a 5 6 ky lag from the minimum insolation during the last glacial maximum variations in the monsoonal climate of the study area over the past 700 years have been reconstructed from the 18 o and 13 c records of a 14 6 cm long stalagmite f4 in fengyu cave showing wet conditions between ad 1550 and ad 1850 the little ice age and relatively dry conditions before and after this interval human impacts on local vegetation since ad 1700 were recorded by the 13 c record of stalagmite f4

the potential of near entrance stalagmites as high resolution terrestrial paleoclimate proxies application of isotope and trace element geochemistry to seasonally resolved chronology abstract sub annually resolved environmental proxies can be valuable archives of climate change but they are rare in terrestrial settings and it can be difficult to verify their annual nature we suggest that speleothems that grow in well ventilated zones of caves may preserve such high resolution records near entrance cave environments are characterized by year round near atmospheric co2 concentrations and are significantly influenced by surface air temperature fluctuations particularly in temperate latitudes previous monitoring studies of a well ventilated temperate latitude cave westcave preserve central texas have documented seasonal variations in the oxygen isotope composition of calcite grown on glass substrates with winter 18o maxima and summer 18o minima as well as seasonal variations in drip water trace element compositions extending this work to a stalagmite wc 3 from the same drip site we find that stalagmite 18o variations are similar in magnitude to the seasonal 18o variations previously observed for calcite grown on glass substrates that stalagmite mg variations have a similar seasonal period with winter minima and summer maxima and that geochemical variations follow stalagmite growth fabric as mm scale couplets comprising thin slow growing compact sparry calcite laminae winters and thicker fast growing porous elongate columnar calcite laminae summers we interpret a high resolution weekly to monthly 52 year record of 18o mg sr and ba in wc 3 and report new monthly measurements of drip water and associated calcite grown on glass substrates we find drip water 18o and mg ca are essentially invariant and that seasonal variations in wc 3 calcite 18o and mg concentration agree well with predicted temperature dependent fractionation between water and calcite wc 3 calcite sr and ba also vary but with higher and more variable frequencies compared to 18o and mg the annual nature of 18o and mg cycles is supported by monitoring and 14c bomb peak chronology we suggest that stalagmite 18o and mg vary primarily in response to large seasonal temperature changes in this setting allowing for unambiguous differentiation between summer and winter calcite growth from such 18o and mg derived sub annual chronologies the timing of enrichments in other geochemical species that are less directly coupled to external cave temperature e g calcite sr and ba can be considered as proxies of other important processes such as water rock interaction in the epikarst precipitation events or subsurface respiration rates the potential for this kind of multi proxy seasonally resolved dating may add near entrance stalagmites to the list ice cores lake varves tree rings of high resolution terrestrial proxies available for paleoclimate studies

first 226ra 210pb dating of a young speleothem whereas the method based on the decrease of excess 210pb has already been used to date young 120 yr speleothems e g m baskaran t m iliffe age determination of recent cave deposits using excess 210pb a new technique geophys res lett 20 1993 603 606 this paper presents the first dating of a speleothem through the 226ra 210pb method dating of a young hydrothermal stalagmite from the mt cornadore cave st nectaire french massif central was made possible by the high 226ra and negligible 210pb contents of such carbonates formed by precipitation from co2 rich thermal waters 210pb 226ra ratios regularly increase with depth along the axis of the 33 cm long stalagmite the age depth relationship can be interpreted by two main phases of growth with high but variable axial growth rates of 5 3 mm yr from 1909 to 1967 and 2 6 mm yr from 1967 to 1989 alternatively the oldest phase can be subdivided in three episodes with growth rates varying from 2 to 7 mm yr thin section examination reveals the presence of numerous laminae indicating infra annual variations we suggest that this fine layered structure might reflect short term fluctuations in drip waters possibly induced by near surface mixing between thermal and ground waters and ultimately linked to the pluviometry a detailed examination of this laminated structure combined with 226ra 210pb dating could thus provide a high resolution record of local paleohydrological fluctuations

solitary waves in the western equatorial pacific ocean during the spring tides of early january and february 1993 groups of solitary intemal waves were observed propagating through the intensive flux array of the toga coare experiment the waves appear to originate near the islands of nugarba 3 s 30 s 154 30 e they travel north eastward at 2 5 3 ds closely coupled with the semi diumal baroclinic tide peak amplitudes exceed 60 m velocities are in excess of 8 ds sea surface vertical displacements of order 3 m can be inferred directly from the lateral acceleration of surface waters the equatorial undercurrent is displaced by soliton passage but apparently is unaffected otherwise the intrinsic shear of the solitary crests is small compared to ambient equatorial shears the crests while not themselves unstable are effective at triggering instabilities on the background flow the motions potentially contribute 10 15 wattdm2 to the flux of heat into the mixed layer

regional arias intensity attenuation relationship for taiwan considering vs30 the arias intensity is a measure of earthquake intensity arrived at through the integration of a square of the acceleration time history it has been demonstrated to be an effective predictor of earthquake damage potential in relation to short period structures liquefaction and seismic slope stability and has begun to be considered as a ground motion measure suitable for use in probabilistic seismic hazard analysis psha as well as earthquake loss estimation a new empirical arias intensity attenuation relationship for shallow crustal earthquakes is developed where both fault type and a continuous site variable vs30 are considered the relationship is based on a large number of strong motion records 6570 from a wide range of earth quake magnitudes 3 9 7 6 from the taiwan strong motion instrument program tsmip network its functional form is modified from that of travasarou et al 2003 which is derived from a point source model and the coefficients are determined through nonlinear regression analyses using a mixed effects model the results show that the incorporation of vs30 can significantly reduce regression error the arias intensity value predicted in the present study is generally similar to that obtained by travasarou et al 2003 but is different in detail being more suitable for usage in psha for a tectonically young orogenic belt like that in taiwan or new zealand

seismic demand of the liquefaction potential with equivalent number of cycles for probabilistic seismic hazard analysis abstractequivalent number of cycles ncyc is a significant factor in assessing liquefaction potential during earthquakes however the effects of ncyc are considered a deterministic value by using a magnitude scaling factor and the uncertainties of these effects have not been included in the current design practice this paper calculates ncyc within the soil mass by deconvolution analysis as a function of the period of soil layer from the ground surface ts and the soil property b using a wide range of acceleration time histories the predictive model of ncyc is developed as variable dependent on earthquake magnitude peak ground acceleration pga and ratio of spectral acceleration ts and b then the ncyc model is combined with the ground motion prediction equation of pga and the prediction equation of seismic shear stress reduction coefficient rd to obtain the prediction equation of the seismic demand of the liquefaction potential k1cyc the standard deviation of k1cyc is also modeled on the

reverse flow in turbidity currents the role of internal solitons pickering hiscott 1985 have demonstrated amply the presence of reverse flow units within the thick bedded calcareous wacke tcw beds of the turbiditic cloridorme formation middle ordovician gaspe peninsula quebec canada these reverse flow units are underlain and overlain by units which reveal flow in the primary obverse direction in this paper a model is proposed for this reverse flow based on the probable nature of the primary turbidity flow it appears that the initial flow was highly elongated thickness h length l with h 500 m velocity u 2 m s 1 and sediment concentration c 1 25 o the rate of momentum loss of the flow is estimated by means of a useful parameter which we call the drag distance symbol dd defined by where h and l are the thickness and length of the flow respectively ccd is a combined drag coefficient representing friction on the bottom and at the upper interface and fcd is a form drag coefficient related to the shape and size of the head dd is the distance travelled by a current of constant h and l flowing over a horizontal bottom and obeying a quadratic friction law for an e fold reduction in velocity simple considerations confirmed by our own experiments described in this paper show that such an elongated turbidity current cannot be reflected as a whole from an adverse slope when the nose of the current reaches the slope it forms a hump which surges backwards and sooner or later breaks up into a series of internal solitons the latter probably numbering 4 7 will cause reverse flow at a given point as they pass by provided that the residual velocity in the tail is not too great flow in the original obverse direction will be re established after the passage of the solitons quiescent periods in front of between and behind the solitons when soliton associated currents cancelled out the residual obverse flow would allow the deposition of thin mud drapes additional flow reversals observed in a few of the tcw beds cannot be explained readily by the re passage of solitons since wave breaking at the ends of the basin would cause massive energy loss internal seiches are the preferred explanation for these later reversals

early stage soliton observations in the sulu sea abstractobservations of early stage large amplitude nonlinear internal waves in the sulu sea are presented water column displacement and velocity profile time series show the passage of two solitary like waves close to their generation site additional observations of the same waves are made as they propagate through the sulu sea basin these waves of depression have an estimated maximum amplitude of 44 m observed wave amplitude and background stratification are used to estimate parameters for both a korteweg de vries k dv and a joseph wave solution these analytic model solutions are compared with a fully nonlinear model as well model wave half widths bracket the observed wave with the joseph model narrower than the k dv model the modal structure of the waves change as they transit northward though the sulu sea with higher mode features present in the southern sulu sea which dissipate by the time the waves reach the north observed and modeled energies are roughly comparable with observed pot

age determination of recent cave deposits using excess 210pb a new technique cave deposits have been widely used as proxy recorders in deciphering palaeoclimate during the last glacial interglacial maxima 120 ka harmon et al 1975 atkinson et al 1978 goede and harmon 1983 ayliffe and veeh 1989 palaeoclimatic studies of cave deposits for the past 1 1000 yr time scale require a precise dating technique that until now has been lacking due to the multiple sources of carbon in speleothems 14c dates obtained for recently deposited calcite are highly variable and thus 14c dating techniques are not suitable to obtain speleothem ages for the past 1 1000 years here we show for the first time that speleothems contain high concentrations of excess 210pb and that this 210pb excess can be successfully employed to obtain growth rates of speleothems deposited during the last 100 years of two specimens analyzed a tubular soda straw stalactite yielded a longitudinal growth rate of 1 1 mm yr while a normal icicle shaped stalactite had a lateral growth rate of 0 028 mm yr the mass growth rates of these two speleothems 149 and 78 mg yr respectively are comparable within a factor of two studies of fine scale variations in the isotopic composition of recent speleothems will help to corroborate the validity of palaeoclimate records obtained using longer lived isotopes and extending back into pleistocene

ground motion prediction equations for hawaii from a referenced empirical approach ground motion prediction equations gmpes for hawaii are developed using the referenced empirical approach the technique is based on the use of residual analysis that models discrepancies between ground motion observations for hawaii and a reference gmpe in this case the gmpe of boore and atkinson 2008 for shallow crustal earthquakes in active tectonic regions the referenced empirical approach provides gmpes for hawaii that are in agreement with regional ground motion observations while being constrained to follow the overall scaling behavior of ground motion that is observed in better instrumented regions gmpes are developed for both shallow depth 20 km and deep 35 to 40 km earthquakes in hawaii

settlement sliding and liquefaction remediation of layered soil a series of highly instrumented large scale centrifuge models have been tested to investigate the extent of remediation required to control settlement and lateral sliding of soil deposits at a hypothetical bridge site the baseline model represents a prototype with a 9 m thick layer of fine sand having a relative density dr of 50 the sand layer is overlain by clay floodplains with a free face at a river channel one nearly level floodplain surface supports a bridge abutment the other floodplain has a 9 slope toward the river in different models different amounts of the 50 relative density sand was densified to dr 80 full depth improvement reduced settlements and lateral sliding of the sand by about a factor of 3 due to the effects at the clay sand interface lateral sliding of the surficial clay deposit was not controlled by densification of the sand tests in which the width of the densified zone was only about 75 of the thickness of the loose sand indicated that relatively narrow zones o

pore pressure and dissipated energy in earthquakes field verification the possibility of a correlation between dynamic pore pressure increase p and dissipated energy density d in soils subjected to earthquake shaking has been the subject of speculation for nearly 20 years while cyclic loading tests have tended to confirm the d p hypothesis in the laboratory no field confirmation has been given in this paper compelling evidence is presented to support the d p model from two real earthquakes downhole acceleration records from two earthquakes are analyzed to obtain approximate histories of shear stress shear strain and dissipated energy over a range of depths the measured data were obtained from the lotung downhole array in taiwan and from the sunamachi downhole array near tokyo both of these arrays also contain pore pressure measurement devices and records of pore pressure increase during the earthquakes are available time histories of measured pore pressure will be directly compared with calculated values based on the d p hypothesis the results of this study suggest dissipated energy density may be remarkably well correlated with pore pressure increase in field situations

growth rate of a deep sea coral using 210pb and other isotopes abstract a deep sea coral was studied to determine its growth rate and to reconstruct time histories of isotope distributions in the deep ocean the specimen was collected at a depth of 600 m off little bahama banks using the deep submergence vehicle dsv alvin the growth rate of the calcitic coral trunk was determined using excess 210pb measured in concentric bands excess 210pb was found in the outer half of the coral s radius and a growth rate of 0 11 0 02 mm a is calculated assuming a constant growth rate during formation of the entire trunk an age of 180 40 a is estimated for the coral the decrease observed in radiocarbon activities measured on the same bands griffin and druffel 1989 concurred with the growth rate estimated from excess 210pb activity 239 240pu activities measured by mass spectrometry were also detected in the outer two bands of the coral as expected from the 210pb chronology stable oxygen and carbon isotopes measured in samples collected by a variety of techniques are positively correlated this is evidence of a variable kinetic isotope effect most likely caused by variations in the skeletal growth rate long lived corals such as this specimen have the potential for serving as integrators of seawater chemistry in the deep sea over several century timescales

palaeoclimatic interpretation of stable isotope data from holocene speleothems of the waitomo district north island new zealand one straw stalactite and three stalagmites from the waitomo district of north island new zealand were examined for stable isotopes of oxygen and carbon with a view to interpreting their palaeoclimate signal dating was by uranium series and ams 14c for the stalagmites and by gamma ray spectrometry for the straw records were thus established for about 100 years for the straw and 3 9 10 1 and 10 2 ka for the stalagmites the range of variability in d18oc and d13cc this century is about two thirds of that experienced over the entire holocene and is most simply explained in terms of the oceanic source area of rain stable isotope variations in three stalagmites show some general similarities but have significant differences in detail which underlines the necessity to base palaeoclimatic interpretations on more than one speleothem record the d18oc of each stalagmite varies positively with temperature indicating the dominance of the ocean source of evaporation in determining the isotopic composition of

prototypical solitons in the south china sea 1 surface signatures associated with non linear internal waves are often seen in satellite images of the western south china sea scs slope and shelf observation in the deep sea to the east are rare here we report on the evolution of an energetic packet as it propagated through the deep central basin of the scs toward the western slope and shelf the waves have amplitudes estimated at 170 m half widths of 3 km and phase speeds of 2 9 0 1 m s faster than the mode 1 linear phase speed of 2 6 m s the shape and observed phase speed were consistent with the korteweg devries kdv model over the 65 km path that they were tracked the intrinsic velocity shear of the waves is small compared to pre existing shears and the waves exhibit weak turbulence the kdv fit and a satellite derived estimate of horizontal wave extent imply a westward energy flux of 4 5 gw for each crest

reconnaissance of two liquefaction sites using small unmanned aerial vehicles and structure from motion computer vision following the april 1 2014 chile earthquake abstractsmall unmanned aerial vehicles suavs were used to reconnoiter image and model the effects of soil liquefaction at two separate sites following the m8 2 and m7 6 earthquakes near iquique

two millennia of tropical cyclone induced mud layers in a northern yucatan stalagmite multiple overlapping climatic hazards during the maya terminal classic megadroughts an annually laminated stalagmite from the northern yucatan peninsula contains mud layers from 256 cave flooding events over 2240 years this new conservative proxy for paleotempestology recorded cave flooding events with a recurrence interval of 8 3 years during the twentieth century with the greatest frequency during the twentieth century and the least frequent during the seventeenth century tropical cyclone tc events are unlikely to flood the cave during drought when the water table is depressed applying tc masking to the chaac paleorainfall reconstruction suggests that the severity of the maya megadroughts was underestimated without a high resolution radiometric geochronology of individual local tc events speleothem isotope records cannot resolve whether the terminal classic period in the northern maya lowlands was punctuated by several brief drought breaks with normal tcs or whether the region was very dry and peppered by unusually severe and frequent hurricane seasons

investigation of cyclic liquefaction with discrete element simulations abstracta discrete element method dem assembly of virtual particles is calibrated to approximate the behavior of a natural sand in undrained loading the particles are octahedral bumpy clusters of spheres that are compacted into assemblies of different densities the contact model is a jager generalization of the hertz contact which yields a small strain shear modulus that is proportional to the square root of confining stress simulations made of triaxial extension and compression loading conditions and of simple shear produce behaviors that are similar to sand undrained cyclic shearing simulations are performed with nonuniform amplitudes of shearing pulses and with 24 irregular seismic shearing sequences a methodology is proposed for quantifying the severities of such irregular shearing records allowing the 24 sequences to be ranked in severity the relative severities of the 24 seismic sequences show an anomalous dependence on sampling density four scalar measures are proposed for predicting th

intra event spatial correlations for cumulative absolute velocity arias intensity and spectral accelerations based on regional site conditions abstract spatial correlations of ground motion intensity measures ims are essential for seismic analysis of spatially distributed systems in this paper geostatistical analysis is conducted to calculate the spatial correlations for cumulative absolute velocity cav arias intensity ia and spectral accelerations sa using a total number of more than 1500 earthquake records from nine recent earthquakes occurred in taiwan california and japan the results indicate that the spatial correlations for these ims are closely related to the regional site conditions and they can be predicted based on the spatial correlations of shear wave velocity in the top 30 m v s 30 in general an im recorded from a relatively homogeneous regional site condition tends to have a larger spatial correlation range than that from a heterogeneous site condition due to their intrinsic similarity to represent the integration of acceleration time histories cav and ia have similar spatial correlation coefficients besides the range of spatial correlation of sa generally increases as the spectral period increases simple predictive equations are proposed in this study to quantify the spatial correlations of cav ia and sa based on regional site conditions methods for data correction are also proposed to eliminate artificial correlations due to biased distance scaling and v s 30 estimation in the database finally monte carlo method is used to generate spatially distributed ims the results demonstrate that the annual frequency of exceedance curves for spatially distributed ims differ significantly if different ranges of spatial correlations are used

generation and propagation of nonlinear internal waves in massachusetts bay 1 during the summer nonlinear internal waves nliws are commonly observed propagating in massachusetts bay the topography of the area is unique in the sense that the generation area over stellwagen bank is only 25 km away from the shoaling area and thus it represents an excellent natural laboratory to study the life cycle of nliws to assist in the interpretation of the data collected during the 1998 massachusetts bay internal wave experiment mbiwe98 a fully nonlinear and nonhydrostatic model covering the generation shoaling region was developed to investigate the response of the system to the range of background and driving conditions observed simplified models were also used to elucidate the role of nonlinearity and dispersion in shaping the nliw field this paper concentrates on the generation process and the subsequent evolution inthe basin themodel was foundtoreproducewell the range of propagation characteristics observed arrival time propagation speed amplitude and provided a coherent framework to interpret the observations comparison with a fully nonlinear hydrostatic model shows that during the generation and initial evolution of the waves as they move away from stellwagen bank dispersive effects play a negligible role thus the problem can be well understood considering the geometry of the characteristics along which the riemann invariants of the hydrostatic problem propagate dispersion plays a role only during the evolution of the undular bore in the middle of stellwagen basin the consequences for modeling nliws within hydrostatic models are briefly discussed at the end

mechanism of internal waves in the luzon strait 1 this study suggests a western boundary current instability generation mechanism for the ocean internal waves a linear model describing this instability is developed and an analytical solution is derived from a zero order complex frequency wavenumber relation the real part of the relation represents a dispersion relation of the generated internal waves and the imaginary part is an exponential growth rate the dispersion relation describes the wave propagation characteristics while the growth rate represents the instability properties the theoretical results are used for the case of the kuroshio east of the luzon strait based on the analysis it is found that for the westward propagating disturbance the kuroshio west wing is unstable and the east wing is stable while the reverse is true for the eastern propagating disturbance the results are used to interpret satellite sar images of the ocean internal waves which were generated in the luzon strait and propagated westward reasonable estimates for the growth rate and propagation velocity are derived from a scale analysis of the kuroshio east of the luzon strait

evolution of nonlinear internal waves in the east and south china seas synthetic aperture radar sar images from ers i have been used to study the characteristics of internal waves northeast and south of taiwan in the east china sea and east of hainan island in the south china sea rank ordered packets of internal solitons propagating shoreward from the edge of the continental shelf were observed in the sar images on the basis of the assumption of a semidiurnal tidal origin the wave speed can be estimated and is consistent with the internal wave theory by using the sar images and hydrographic data internal waves of elevation have been identified in shallow water by a thicker mixed layer as compared with the bottom layer on the continental shelf the generation mechanism includes the influences of the tide and the kuroshio intrusion across the continental shelf for the formations of elevation internal waves the effects of water depth on the evolution of solitons and wave packets are modeled by the nonlinear kortweg devries kdv type equation and linked to satellite image observations the numerical calculations of internal wave evolution on the continental shelf have been performed and compared with the sar observations for a case of depression waves in deep water the solitons first disintegrate into dispersive wave trains and then evolve to a packet of elevation waves in the shallow water area after they pass through a turning point of approximately equal layer depths that has been observed in the sar image and simulated by the numerical model the importance of the dissipation effect in the coastal area is also discussed and demonstrated

erratum for shear wave velocity based probabilistic and deterministic assessment of seismic soil liquefaction potential by r kayen r e s moss e m thompson r b seed k o cetin a der kiureghian y tanaka and k tokimatsu

climate variability in central china over the last 1270 years revealed by high resolution stalagmite records oxygen and carbon isotopic variations in the upper section of a stalagmite sf 1 from buddha cave 33 40 n 109 05 e dated by 230th 234u 210pb and lamination counting to a time resolution as fine as 1 3 years have recorded climate changes in central china for the last 1270 years the changes include those corresponding to the medieval warm period little ice age and 20th century warming lending support to the global extent of these events the isotopic records also show cycles of 33 22 11 9 6 and 7 2 years the 33 year cycle could well represent the 35 year periodicity of climate fluctuations previously recognized in china and europe cycles of 22 11 and 9 6 years have often been associated with the sunspot or lunar orbit variations the 7 2 year cycle was recently identified also in tree ring records from an area close to buddha cave these cycles suggest that external forcing e g solar irradiance may affect the summer monsoon over eastern china the general consistency between the climate characteristics inferred from the stable isotope records of sf 1 and those from other proxy records underscores the value of stalagmites as recorders of paleoclimate

speleothem evidence for temporal spatial variation in the east asian summer monsoon since the medieval warm period published annual to decadal resolution stalagmite d 18 o records since ad 900 from six caves dongge furong heshang buddha shihua and wanxiang in china were analyzed to detect temporal and spatial variability of the east asian summer monsoon strength which strongly affects wet dry conditions in eastern china the empirical mode decomposition method was used to obtain trends of the six cave records after the base trend was determined d 18 o anomalies of each record were computed by subtracting the base trend mean d 18 o anomaly values of the detrended time series for each cave record were calculated for four periods i medieval warm period mwp ad 900 1250 ii little ice age phase 1 lia 1 ad 1250 1550 iii little ice age phase 2 lia 2 ad 1550 1850 and iv modern period md ad 1850 2000 from these anomalies the temporal and spatial variability of wet dry conditions has been identified positive values of the mean d 18 o anomalies indicating drier conditions appeared in the lower yangtze river drainage area and southeast coast area during md 1 lia 1 and mwp whereas negative values existed in north south and yangtze areas of eastern china during lia 2 the results agree with the dryness wetness index reconstructed by chinese historic records in general these results illustrate that wet and dry conditions in different regions of eastern china could be opposite under monsoon influence so that no single speleothem d 18 o record could represent the monsoonal climate in this vast region climatic patterns in the monsoonal region can be either a combination of warm wet and cold dry or a combination of cold wet and warm dry on annual to centennial scales a 128 year periodic cycle exists in all six cave records whereas 64 year possibly a harmonic of 128 year periodicity and 42 year periodicities appear in shihua heshang and dongge records these cycles may reflect the influence of solar activity on the east asian summer monsoon copyright 2012 john wiley sons ltd