strontium distribution in the shell of the aragonite bivalve arctica islandica 1 the behavior of sr in the aragonite shells of the bivalve arctica islandica has been explored to determine its potential for high resolution environmental reconstruction the structural state of sr in the shell was investigated using x ray absorption fine structure xafs and sr ca variations across the prismatic layer in the umbo and outer shell were determined by secondary ionization mass spectrometry sims and laser ablation inductively coupled plasma mass spectrometry la icp ms respectively xafs data suggest that sr randomly substitutes for ca within the shell aragonite sr ca in both the umbo and the outer shell exhibits significant seasonal variation but does not correlate with seawater temperature sr ca varies significantly between parallel transects across the same annual bands sr concentrations are highest in transects along the maximum growth axis of the outer shell but lowest in these transects in the umbo scanning electron microscopy indicates changes in crystal morphology both within and between transects we do not however observe a clear relationship between shell growth rate and sr ca fluctuations in sr ca are most likely to be controlled by a complex interaction of biological and kinetic processes

strong biological controls on sr ca ratios in aragonitic marine bivalve shells 1 it is well known that skeletal remains of carbonate secreting organisms can provide a wealth of information about past environments sr ca ratios have been successfully used as a temperature proxy in corals and sclerosponges previous work on aragonitic bivalve shells has not been conclusive but suggests a major control of growth rate on sr ca ratios as many studies have used bivalve growth rates to determine temperature we tested if sr ca ratios could predict temperature through its relationship with growth rate shells from the two species of clams from the same family veneroidea studied here saxidomus giganteus and mercenaria mercenaria show vastly different seasonal sr ca profiles a strong relationship between average annual sr ca ratios and annual growth rate was found in s giganteus shells from both washington r2 0 87 and alaska r2 0 64 usa but not in m mercenaria shells from north carolina usa furthermore the sr ca growth rate relationship was also evident upon a more detailed inspection of subannual growth rates in s giganteus r2 0 73 although there were significant positive correlations between sr ca ratios and temperature in s giganteus shells the correlations were weak 0 09 r2 0 27 and thus sr ca ratios cannot be used as a reliable temperature proxy in these species of aragonitic bivalves it is clear from this study that sr ca ratios are not under thermodynamic control in either clam species since thermodynamics predict a negative correlation between sr ca ratios and temperature in aragonite this points toward dominance of biological processes in the regulation of sr2 this is also reflected by the largely differing sr ca partition coefficients dsr in these shells dsr 0 25 when compared to inorganic coral and sclerosponge studies dsr 1 all of which show a negative dependence of sr ca on temperature we suggest that caution be taken when using sr ca in any biogenic aragonite as a temperature proxy when the dsr greatly deviates from one as this indicates the dominance of biological controls on sr ca ratios

quasi real time fault model estimation for near field tsunami forecasting based on rtk gps analysis application to the 2011 tohoku oki earthquake mw 9 0 1 real time crustal deformation monitoring is extremely important for achieving rapid understanding of actual earthquake scales because the measured permanent displacement directly gives the true earthquake size seismic moment mw information which in turn provides tsunami forecasting we have developed an algorithm to detect estimate static ground displacements due to earthquake faulting from real time kinematic gps rtk gps time series the new algorithm identifies permanent displacements by monitoring the difference of a short term average sta to a long term average lta of the gps time series we assessed the noise property and precision of the rtk gps time series with various baseline length conditions and orbits and discerned that the real time ephemerides based on the international gnss service igs are sufficient for crustal deformation monitoring with long baselines up to 1 000 km we applied the algorithm to data obtained in the 2011 off the pacific coast of tohoku earthquake mw 9 0 to test the possibility of coseismic displacement detections and further we inverted the obtained displacement fields for a fault model the inversion estimated a fault model with mw 8 7 which is close to the actual mw of 9 0 within five minutes from the origin time once the fault model is estimated tsunami waveforms can be immediately synthesized using pre computed tsunami green s functions the calculated waveforms showed good agreement with the actual tsunami observations both in arrival times and wave heights suggesting that the rtk gps data by our algorithm can provide reliable rapid tsunami forecasting that can complement existing tsunami forecasting systems based on seismic observations

tide gage response to tsunamis part ii other oceans and smaller seas abstract extending previous work in the north pacific tsunami response was examined in the atlantic and indian oceans and in three smaller seas with the objective of exploring scale effects energy diffusing from the chilean tsunami of 22 may 1960 was tracked through windows around antarctica into all three oceans simultaneously reaching maximum intensity about 39 h after quake time in smaller seas spectral response was again characteristically an exacerbation of normal background with principal energy in the fundamental pumping mode of the local coastal shelf subsequent to diffusion isotropic energy decay was uniformly exponential except that the diffusion and decay e folidng times were different in each sea an ad hoc energy flux decay model with a constant linear friction coefficient suffices to explain the observed decay times in terms of basin geometries the model has several spinoffs it accounts for about half the observed coastwise variation in tsunami intensity it may possibly

some tsunami characteristics deducible from tide records abstract after an initial 40 hour diffusion period the time decay of tsunami variance was found to be uniformly exponents for 28 events among eight pacific tide stations thew results essentially confirm munk s acoustic deny hypothesis except that the decay e folding time 22 h more nearly equated the ocean s normal mode transit time 21 h than munk s mean collision time 14 h relative tsunami energy obtained by extrapolating exponential decay back to t 0 was found to be similarly ranked among tsunamis at all stations and roughly proportional to seismic energy a total energy estimate for the tsunami of 9 march 1957 obtained by correcting the observed energy decay at wake island for instrument and island response provided normalized total energy estimates for all tsunamis that were consistent with independent estimates by kajiura and by aida similarities between power spectra computed from these time series suggests that station response is primarily linear normal mode forcing of the conti

structure of lower carboniferous basins of nw ireland and its implications for structural inheritance and cenozoic faulting abstract the geometry of lower carboniferous basins across the northern part of ireland is characterised by a gradual change in polarity of structure from a predominantly southward dipping fault system in northern ireland through the lough allen basin and into a mainly northward dipping fault system of connemara in the southwest this polarity change is reflected in the emergence of northward facing uplifted footwall blocks such as at croagh patrick and the ox mountains in the southwest with southward facing blocks in the northeast despite these structural changes there is a great degree of along strike continuity of lower carboniferous structure strain and displacement with the system forming a link between comparable sized and coeval basins in northern england and scotland to the east and the canadian maritime provinces to the west the spatial distribution of carboniferous normal faults suggests that caledonian structure such as the fair head clew bay line plays an important role in the localisation of post caledonian strain although the reactivation of individual caledonian structures may be less common the terrain of the west of ireland is strongly influenced by major carboniferous faults offsetting the base carboniferous unconformity as opposed to previously suggested cenozoic normal faulting of a tertiary peneplain

crystal fabrics and element impurities sr ca mg ca and ba ca in shells of arctica islandica implications for paleoclimate reconstructions sr ca mg ca and ba ca values are heterogeneously distributed in shells of arctica islandica these patterns are largely associated with crystal fabrics size habit and orientation of crystals or the processes controlling them the outer sublayer of the outer shell layer oosl homogenous and irregular simple prismatic crystal fabrics contained element ca values up to 62 higher than the inner sublayer iosl crossed acicular crossed lamellar fine crossed lamellar and irregular simple prismatic crystal fabrics a gradual decrease in sr ca and mg ca values was observed from the outer portions of the oosl toward the oosl iosl transition zone this chemical shift was accompanied by a gradual transition from homogenous crystal fabrics into crossed lamellar acicular crystal fabrics near annual growth lines irregular simple prisms i e during periods of slow growth sr and mg seemed to be deposited in equilibrium with the ambient environment because the sr ca and mg ca values approached values typical for seawater during the remainder of the growing season sr ca and mg ca remained far below values expected for thermodynamic equilibrium ba ca peaks however occurred erratically at different times of the year without any noticeable changes in crystal fabrics likely the environmental information contained in these peaks was less severely filtered by vital effects than in sr and mg the findings of the present study can help to develop new techniques with which extract environmental signals from the metal to calcium ratios of bivalve shells

excitation of basin wide modes of the pacific ocean following the march 2011 tohoku tsunami this study is an attempt towards understanding the sources of long oscillations observed within the pacific ocean following the 11 march 2011 tohoku earthquake we present evidence that extremely long modes of the pacific ocean in the range of 2 48 h were excited by this giant tsunami a numerical approach was employed to calculate the basin wide modes of the pacific ocean resulting in 49 modes in the range of 2 48 h we studied 15 tide gauge records around the pacific ocean in order to extract basin wide modes of the pacific ocean excited by this transoceanic tsunami spectral analysis of these tide gauge records showed that some of the calculated basin wide modes were indeed excited by the tohoku tsunami the observed modes ranged from 2 to 49 8 h we attributed the long oscillations of the pacific ocean during the 2011 tohoku tsunami to the excitation of these basin wide modes which can be grouped into global modes 15 48 h and regional modes 2 15 h we classified the signals on the tide gauges into three groups 1 basin wide modes 1 5 h 2 the tsunami source periods 20 90 min and 3 local bathymetric effects 20 min the average contributions to the total tsunami energy were 6 4 for the basin wide mode 64 1 for the tsunami source and 29 5 for the local bathymetry although the ratios varied from station to station simulations suggest that the amount of contribution of basin effects to the total tsunami energy depends on the location of the tsunami source

numerical modeling of the 26 november 1999 vanuatu tsunami 1 on 26 november 1999 at 1321 ut central vanuatu was struck by a large offshore earthquake mw 7 5 followed by a tsunami that killed five people and caused significant damage to nearshore structures mainly at martelli bay south pentecost island the tsunami is simulated using the geowave model the tsunami open and progressive initial conditions system topics source component of the model simulates the initial water column deformation and the propagation and runup are simulated with the funwave fully nonlinear boussinesq and dispersive model a special effort was made on the construction of the computational grid through comprehensive bathymetry data sets obtained especially from two multibeam bathymetric surveys performed after the earthquake and tsunami three different tsunami sources have been considered the first one is the fault rupture itself the second is a landslide located east of ambrym island and the third source is a submarine structure within the selwyn strait that will be considered as a landslide however with a large uncertainty because it could be a result of lava deposit as well it is found that the earthquake derived tsunami source fits most of the postsurvey observations in particular the overall wave amplitudes up to 6 7 m observed and simulated the timing of the tsunami is also satisfactory when objective interpretation of the eyewitnesses is processed thus it is found that the hypothetical landslide derived tsunami contributions are not necessary to predict the tsunami this is because they do not help in the tsunami timing but also because their wave amplitude contributions are one order of magnitude lower than that of the earthquake source

a gravity and magnetic interpretation of the structure of the irish midlands and its relation to ore genesis regional gravity and magnetic data from the irish midlands have been studied in an attempt to map the structures within and beneath the lower carboniferous limestones the magnetic data suggest that the precambrian crystalline basement is at a depth of 3 4 km and is overlain by ordovician volcanics of varying magnetization a fourier analysis of the gravity field has been used to construct a residual gravity map which represents principally the gravity effect of shallow sources these sources are probably the topographic variations of dense ordovician volcanics beneath a less dense succession of ordovician to carboniferous sediments the residual gravity clearly shows the presence of a series of linear volcanic blocks and sedimentary troughs trending ne sw the major mineralized zones in the area all occur close to the margins of these troughs this investigation indicates that the initial position of the midland plain was controlled by caledonide factors some of which modified the later subsidence which we attribute to hercynian plate margin processes the genesis of the major ore bodies is probably associated with de watering of the shale filled troughs the subsequent concentration of metal bearing fluids along the trough margins and their deposition in relatively unloaded carbonate host rocks on the up standing blocks

near field tsunami models with rapid earthquake source inversions from land and ocean based observations the potential for forecast and warning computation of tsunami models in the region adjacent to large earthquakes immediately after rupture initiation remains a challenging problem limitations of traditional seismological instrumentation in the near field and concern by tsunami modelers regarding the nonuniqueness of source inversions and the use of indirect observations have in the past been hurdles for such efforts employing near field data from the mw 9 0 2011 tohoku oki data we test source models obtained from newly developed algorithms and multisensor data we demonstrate the ability of such source models determined from land based coseismic data from the combination of gps and strong motion sensors to forecast near source tsunamis we also demonstrate that rapid ingestion of offshore shallow water 100 1000 m wave gauge data substantially improves the earthquake source and tsunami forecast to assess the success of such tsunami models we rely on detailed comparisons to 2000 tsunami survey measurements collected after the event we argue that deployments of shallow water wave gauges coupled with land based geophysical sensors can in the future provide enough information to issue timely and accurate forecasts of tsunami intensity immediately or shortly after rupture initiation of large earthquakes

calibrating the element composition of donax deltoides shells as a palaeo salinity proxy abstract bivalve shell chemistries provide valuable insights into past environments if relationships between shell chemistry and environmental conditions are known this study assessed the suitability of goolwa cockle donax deltoides shell element composition as an environmental proxy for southern australia a region lacking high resolution environmental records cockles were collected along an environmental gradient and the element composition of corresponding water and shell samples were quantified using a combination of icp aes and icp ms for water samples and la icp ms for shells of the elements analysed ba ca li ca and mg ca in shells reflected ambient water chemistries shell ba ca concentrations showed a significant negative relationship with recorded salinities and a positive non significant trend was observed between mg ca and water temperature further assessment of environmental and biological controls on element incorporation are required however ba ca in d deltoides shells appears a suitable palaeo salinity tool and has the potential to provide an easily accessible and valuable proxy to gain insights into past environmental conditions over extensive time scales

japan s 2011 tsunami characteristics of wave propagation from observations and numerical modelling we use a numerical tsunami model to describe wave energy decay and transformation in the pacific ocean during the 2011 tohoku tsunami the numerical model was initialised with the results from a seismological finite fault model and validated using deep ocean bottom pressure records from darts from the neptune canada cabled observatory as well as data from four satellite altimetry passes we used statistical analysis of the available observations collected during the japan 2011 tsunami and of the corresponding numerical model to demonstrate that the temporal evolution of tsunami wave energy in the pacific ocean leads to the wave energy equipartition law similar equipartition laws are well known for wave multi scattering processes in seismology electromagnetism and acoustics we also show that the long term near equilibrium state is governed by this law after the passage of the tsunami front the tsunami wave energy density tends to be inversely proportional to the water depth this fact leads to a definition of tsunami wave intensity that is simply energy density times the depth this wave intensity fills the pacific ocean basin uniformly except for the areas of energy sinks in the southern ocean and bering sea

the 2011 tohoku oki earthquake tsunami similarities and differences to the 869 jogan tsunami on the sendai plain a post tsunami field survey following the 2011 tohoku oki earthquake tsunami was carried out to asses inundated area in sendai plain northeast japan the type of inundation was classified into two categories major and minor according to the amount of accumulated debris garbage and sediment major and minor inundations were identified up to 4 and 5 km from the coastline respectively many artificial geomorphological features such as roadway embankments and canals were believed to have affected the run up process of the tsunami the inundation area of the 2011 tsunami on the sendai plain is compared with that of the 869 jogan tsunami which was reconstructed using numerical modeling based on available historical and geological records the inundation area of the 2011 tohoku oki tsunami is comparable to that of the 869 jogan tsunami although a direct comparison is difficult due to differences in geomorphological contexts between the paleo period and the present

reconstructing the history of fluid flow at cold seep sites from ba ca ratios in vesicomyid clam shells hydrogen sulfide discharge at cold seep sites is recorded as enrichment in the barium to calcium ba ca ratio in shells of vesicomyid clams collected live from cold seeps in monterey canyon and the cascadia margin a direct relationship between increased ba fluxes from cold seeps and ba incorporation into shells was established for the cascadia margin site for the monterey canyon site a 2 yr episode of high fluid flow centered on 1992 was inferred from coherent changes in the ba ca profiles of threecalyptogena kilmerishells comparison with precipitation and d 18 o data indicates that this high flow period may have been driven by an increase in rainfall after the 1988 1990 california drought high resolution records preserved in clam shells are shown to be useful in elucidating characteristics history and possible mechanisms driving fluid discharge at continental margin seeps thus establishing their potential use as paleotracers of fluid seepage events an extensive set of geophysical and geochemical measurements is currently available to document the flow and expulsion of fluids at transform and convergent margins it is now recognized that such fluid discharge has far reaching implications that include hydrocarbon prospecting benthic ecosystem structure and function and groundwater research moore 1999 at present we are unable to incorporate geochemical data from cold seeps to models quantifying their effects on marine geochemical budgets because we lack a clear understanding of the spatial and temporal variability of these systems and of the mechanisms responsible for the advective transport however vent macrofauna may afford such an opportunity by recording in their shells the immediate environment in which they grow and thereby allowing us to reconstruct the variability in fluid discharge rates vesicomyid clams live in association with sites of sulfide 1

210po 210pb dating of recent volcanic eruptions on the sea floor the globe encircling mid ocean ridge system accounts for most of the earth s volcanism and influences its heat budget morphology and the composition of the oceans it is therefore important to constrain the size frequency and compositional variability of ridge eruptions but this is made difficult by the remoteness of much of the sea floor and the paucity of applicable radioactive chronometers remote monitoring has provided indirect evidence for active ridge volcanism1 3 which in some cases has been strengthened by submersible observations4 5 but it has not been possible to date these eruptions directly here we present a new chronometer based on 210po 210pb radioactive disequilibrium which allows us to date glassy eruption products within a few years of their eruption our first results on lavas from 9 50 n on the east pacific rise confirm that the ridge erupted only months before sample collection and indicate that the eruptions extended over at least one year the chronometer begins with po volatilization during eruption all glasses analysed were 75 100 degassed a crystalline pillow interior was 20 degassed however implying that the flow surface may control po degassing during deep submarine eruptions although the 210po 210pb chronometer is useful for only a short time frame it should prove valuable for dating recent but unobserved submarine eruptions and determining details of eruptive sequences

joint inversion of strong motion teleseismic geodetic and tsunami datasets for the rupture process of the 2011 tohoku earthquake 1 the 2011 tohoku earthquake was observed by dense strong motion teleseismic geodetic and tsunami networks we first inverted each of the datasets obtained by the networks separately for the rupture process of the earthquake we then performed checkerboard resolution tests for assessing the resolving power of these datasets in order to overcome the limited resolutions of the separate inversions and differences in their results we performed a quadruple joint inversion of all these data to determine a source model most suitable for explaining all the datasets in the obtained source model the maximum coseismic slip was approximately 35 m and the total seismic moment was calculated to be 4 2 1022 nm which yielded mw 9 0 the main rupture propagated not only in the strike direction but also in the dip direction and included both the deep area called the miyagi oki region and the compact shallow area near the japan trench

radioisotopic studies of submarine hydrothermal vents the importance of mid ocean ridge hydrothermal systems has been recognized for their role in the regulation of ocean and sediment chemistry as well as for providing a chemosynthetic source of carbon which drives a unique population of animals found at hydrothermal vents despite the importance of these systems the rates length and depth scale of submarine hydrothermal processes are not precisely known because they are for the most part inaccessible to observational tools we must therefore rely on indirect methods to quantify these processes one way of investigating the rates or timescales of processes in a hydrothermal or any natural system is through the study and modeling of naturally occurring radioisotopes disequilibria among the naturally occurring radioactive decay series in vent fluids associated mineral deposits and overlying effluent plume have provided geochemical tools to investigate the rates of various processes occurring in submarine hydrothermal systems because the half lives of the radioisotopes vary from days to many years processes which encompass a wide range of spatial and temporal scales can be studied this paper presents a review of methods that estimate the residence time of hydrothermal fluids in the ocean crust establish the geochronology of seafloor sulfide deposits investigate the rates of chemical reactions within hydrothermal effluent plumes and derive the heat and mass flux from seafloor hydrothermal areas

linear and nonlinear computations of the 1992 nicaragua earthquake tsunami numerical computations of tsunamis are made for the 1992 nicaragua earthquake using different governing equations bottom frictional values and bathymetry data the results are compared with each other as well as with the observations both tide gauge records and runup heights comparison of the observed and computed tsunami waveforms indicates that the use of detailed bathymetry data with a small grid size is more effective than to include nonlinear terms in tsunami computation linear computation overestimates the amplitude for the later phase than the first arrival particularly when the amplitude becomes large the computed amplitudes along the coast from nonlinear computation are much smaller than the observed tsunami runup heights the average ratio or the amplification factor is estimated to be 3 in the present case when the grid size of 1 minute is used the factor however may depend on the grid size for the computation

modeling of the 2011 japan tsunami lessons for near field forecast during the devastating 11 march 2011 japanese tsunami data from two tsunami detectors were used to determine the tsunami source within 1 5 h of earthquake origin time for the first time multiple near field tsunami measurements of the 2011 japanese tsunami were used to demonstrate the accuracy of the national oceanic and atmospheric administration noaa real time flooding forecast system in the far field to test the accuracy of the same forecast system in the near field a total of 11 numerical models with grids telescoped to 2 arcsec 60 m were developed to hindcast the propagation and coastal inundation of the 2011 japanese tsunami along the entire east coastline of japan using the noaa tsunami source computed in near real time the model results of tsunami propagation are validated with tsunami time series measured at different water depths offshore and near shore along japan s coastline the computed tsunami runup height and spatial distribution are highly consistent with post tsunami survey data collected along the japanese coastline the computed inundation penetration also agrees well with survey data giving a modeling accuracy of 85 5 for the inundation areas along 800 km of coastline between ibaraki prefecture north of kashima and aomori prefecture south of rokkasho the inundation model results highlighted the variability of tsunami impact in response to different offshore bathymetry and flooded terrain comparison of tsunami sources inferred from different indirect methods shows the crucial importance of deep ocean tsunami measurements for real time tsunami forecasts the agreement between model results and observations along japan s coastline demonstrate the ability and potential of noaa s methodology for real time near field tsunami flooding forecasts an accurate tsunami flooding forecast within 30 min may now be possible using the noaa forecast methodology with carefully placed tsunameters and large scale high resolution inundation models with powerful computing capabilities

comparison of earthquake source models for the 2011 tohoku event using tsunami simulations and near field observations selection of the earthquake source used in tsunami models of the 2011 tohoku event affects the simulated tsunami waveform across the near field different earthquake sources based on inversions of seismic waveforms tsunami waveforms and global positioning system gps data give distinguishable patterns of simulated tsunami heights in many locations in tohoku and at near field deep ocean assessment and reporting of tsunamis dart buoys we compared 10 sources proposed by different research groups using the geoclaw code to simulate the resulting tsunami several simulations accurately reproduced observations at simulation sites with high grid resolution many earthquake sources produced results within 20 difference from the observations between 38 and 39 n including realistic inundation on the sendai plain reflecting a common reliance on large initial seafloor uplift around 38 n 0 5 143 25 e 0 75 as might be expected dart data was better reproduced by sources created by inversion techniques that incorporated dart data in the inversion most of the earthquake sources tested at sites with high grid resolution were unable to reproduce the magnitude of runup north of 39 n indicating that an additional source of tsunamigenic energy not present in most source models is needed to explain these observations online material figures of buoy inundation and run up simulations and observations associated data sets and simulation code

traveltime delay relative to the maximum energy of the wave train for dispersive tsunamis propagating across the pacific ocean the case of 2010 and 2015 chilean tsunamis

the recent fault scarps of the western alps france tectonic surface ruptures or gravitational sackung scarps a combined mapping geomorphic levelling and 10be dating approach abstract in the western alps some recent scarps were previously interpreted as surface ruptures of tectonic reverse and normal faults that agree with microseismicity and gps measurements our analysis shows that in fact there are hundreds of recent scarps up to 30 m high and 2 1 km long with only pure normal motions they share the same characteristics as typical sackung scarps the scarps are mainly uphill facing parallel to the ridge crests and the contour lines they are relatively short less than 2 1 km with respect to tectonic fault ruptures and organized in swarms they cut screes and relict rock glaciers with a slow commonly 1 mm year average slip rate in the aiguilles grives massif these sackung scarps clearly express the gravitational toppling of sub vertical bedding planes in hard rocks in contrast the belledonne outer crystalline massif exhibits scarps that stem from the gravitational reactivation of conjugate tectonic faults the recent faults extend to about 1600 m beneath the rognier ridge crest but are always above the valley floor the main scarp swarm is 9 2 km long and constitutes the largest sackung ever described in the western alps 10 be dating of a scarp and offset surfaces shows that 4 m slip may have occurred rapidly in less than 3800 years sometimes between the end of the glaciation and 8800 1900 years ago this dating together with the location of some faults far from the deep glacial valleys suggests that sagging might have been triggered by strong earthquakes during a post glacial period of probably enhanced seismicity the belledonne and synclinal median faults just beneath the rognier sackung could have been the sources of this seismicity

sr ca profile of long lived tridacna gigas bivalves from south china sea a new high resolution sst proxy abstract high resolution 18o and sr ca ratio profiles of a modern live caught and a fossil dead collected giant bivalve shell tridacna gigas from northern south china sea were analyzed the high resolution 18o profiles as documented in most of previous studies showed pronounced seasonal cycles and recorded the combined influence of seawater 18o and sea surface temperature the sr ca ratio profiles derived from icp oes had well defined annual cycles and significant and negative correlation with sea surface temperature while the sr ca profiles derived from la icp ms did not reveal clear annual cycles this difference was likely caused by the organics contents in t gigas shells which had a chemical composition different than caco3 crystals and a heterogeneous distribution across the shell the sampling methods and the experimental errors two calibration equations between sr ca ratios determined by icp oes of modern t gigas shell and instrumental sst were calculated based on all monthly and extremum sst data and the equation from extremum data produced better sst predictions these results suggested that the high resolution icp oes derived sr ca ratios of t gigas in the south china sea had the potential of providing a good proxy of historical sst

synthesizing ocean bottom pressure records including seismic wave and tsunami contributions toward realistic tests of monitoring systems the present study proposes a method for synthesizing the ocean bottom pressure records during a tsunamigenic earthquake firstly a linear seismic wave simulation is conducted with a kinematic earthquake fault model as a source then a nonlinear tsunami simulation is conducted using the sea bottom movement calculated in the seismic wave simulation by using these simulation results this method can provide realistic ocean bottom pressure change data including both seismic and tsunami contributions a simple theoretical consideration indicates that the dynamic pressure change caused by the sea bottom acceleration can contribute significantly until the duration of 90 s for a depth of 4000 m in the ocean the performance of a tsunami monitoring system was investigated using the synthesized ocean bottom pressure records it indicates that the system based on the hydrostatic approximation could not measure the actual tsunami height when the time does not elapse enough the dynamic pressure change and the permanent sea bottom deformation inside the source region break the condition of a simple hydrostatic approximation a tsunami source estimation method of tfish is also examined even though the synthesized records contain a large dynamic pressure change which is not considered in the algorithm tfish showed a satisfactory performance when 5 min after the earthquake occurrence the pressure records synthesized in this study including both seismic wave and tsunami contributions are more practical for evaluating the performance of our monitoring ability whereas most tsunami monitoring tests neglect the seismic wave contribution

glacio seismotectonics ice sheets crustal deformation and seismicity abstract the last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity this growth has been driven largely by the emergence of postglacial rebound models pgm constrained by new field observations that incorporate increasingly realistic rheological mechanical and glacial parameters in this paper we highlight some of these recent field based investigations and new pgms and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation the emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern canada and fennoscandia however many of these models neglect important parameters such as topography lateral variations in lithospheric strength and tectonic strain built up during glaciation in glaciated mountainous terrains glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields in general the short term response to ice fluctuations is similar to the earth s response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre existing stress state when the ice fluctuations occur on the spatial scale and magnitude of the late pleistocene glaciation and deglaciation however the viscoelastic response of the earth especially the mantle causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex the regions of greatest ice thickness and the regions marginal to the late pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting the mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused and continues to cause measureable crustal deformation at hundreds of kilometres from the ice margins for both tectonically active and cratonic regions palaeoseismic investigations of late pleistocene and holocene faults are an important tool in evaluating earthquake hazard the predicted response of the earth over this time however is very dependent on the model assumed for most regions far more carefully designed field observations are needed to constrain the existing rheological and ice models

tsunami coda across the pacific ocean following the 2011 tohoku oki earthquake abstract a tsunami coda lasting more than 5 days was clearly recorded across the pacific ocean following the 2011 tohoku oki earthquake we found that the coda energy per unit area elapsed time of 60 96 hr from the earthquake origin time does not show a systematic variation with respect to the travel distance at the stations located at sea depths deeper than 2000 m whereas the maximum amplitude near the source is significantly larger than those of the far field stations this feature is similar to that of a seismic coda in the sense that the coda energy is distributed uniformly in space the average tsunami coda decays with a decay time of 24 hr when we carefully examined the tsunami waveform near japan a large amplitude wave was identified at an elapsed time of 48 hr which corresponds to the round trip travel time for waves reflected from chile to investigate the excitation mechanisms of the tsunami coda we conducted a tsunami simulation using a global model although linear long wave tsunami equations were found to overestimate the observed coda amplitude the equations including an intrinsic energy loss could successfully simulate the observed coda decay if a bottom friction coefficient of 10 5 was assumed this indicates that not only wave scattering but also intrinsic energy loss plays an important role in the tsunami coda excitation and decay process

new age data for mid atlantic ridge hydrothermal sites tag and snakepit chronology revisited the chronologies of tag and snakepit hydrothermal fields have been established using 210pb pb 230th 234u and 14c dating at the tag field a mn oxide record indicative of low temperature events began at least 125 000 years and possibly 140 000 years ago with maximum intensities at 15 000 7000 and 4000 years before present high temperature events giving rise to sulfide deposits began about 100 000 years ago and have been intermittent to the present day a presently active site has experienced intermittent pulses of activity every 4000 to 6000 years over the past 20 000 years decrease in activity is often marked by low temperature aragonite precipitation in chimney conduits at 4000 7000 and 9000 years ago after a period of quiescence lasting about 4000 years this site was reactivated about 50 years ago the snakepit field is much younger and no sulfides older than 4000 years have been recovered relict sulfide deposits are dated between 2000 and 4000 years old indicating this site was active during a quiescent period at tag reactivation of snakepit took place about 80 years ago and is presently concurrent with that of tag comparison with hydrothermal sites on the east pacific rise suggests that on slow spreading ridges the major fracture systems focussing the hydrothermal discharge can be reactivated at intervals and new deposits precipitated on top of older ones while on faster spreading ridges each pulse of activity is separated in space and time resulting in discrete deposits

the open ocean energy decay of three recent trans pacific tsunamis 1 the 2009 samoa mw 8 1 2010 chile 8 8 and 2011 tohoku 9 0 earthquakes generated destructive tsunamis recorded by a large number of dart stations in the pacific ocean high resolution 15 s dart records yield mean energy decay times for these events of 17 3 24 7 and 24 6 h respectively we attribute these differences to the frequency content of the tsunamis specifically the samoa tsunami was a high frequency event with periods of 2 30 min whereas the chile and tohoku tsunamis were broad band events with periods of 2 180 min differences in frequency content are linked to differences in the source parameters samoa was a relatively small deep water earthquake while chile and tohoku were extensive shallow water earthquakes frequency dependent analysis of the chile and tohoku tsunamis indicates that shorter period waves attenuate much faster than longer period waves decay times range from 15 h for 2 6 min waves to 29 h for 60 180 min waves

possible late pleistocene faulting in iar west connacht ireland caledonian and hercynian faults in iar connacht have been examined for evidence of quaternary movements dip slip displacements are detected both through preservation of scarps and in areas of greater denudation through morphological offsets the principle sites of this phenomenon are the maum clifden and gabhla shannaveara faults tectonic scarps are distinguished from those due to differential erosion and glacial scour earthquake risk in iar connacht though slight is not non existent

w phase inversion and tsunami inundation modeling for tsunami early warning case study for the 2011 tohoku event centroid moment tensor solutions for the 2011 tohoku earthquake are determined by w phase inversions using 5 and 10 min data recorded by the full range seismograph network of japan f net by a scaling relation of moment magnitude to rupture area and an assumption of rigidity of 4 1010 n m 2 simple rectangular earthquake fault models are estimated from the solutions tsunami inundations in the sendai plain minamisanriku rikuzentakata and taro are simulated using the estimated fault models then the simulated tsunami inundation area and heights are compared with the observations even the simulated tsunami heights and inundations from the w phase solution that used only 5 min data are considerably similar to the observations the results are improved when using 10 min of w phase data these show that the w phase solutions are reliable to be used for tsunami inundation modeling furthermore the technique that combines w phase inversion and tsunami inundation modeling can produce results that have sufficient accuracy for tsunami early warning purposes

the long lived mollusc arctica islandica a new paleoceanographic tool for the reconstruction of bottom temperatures for the continental shelves of the northern north atlantic ocean the carbonate shell of the bivalve arctica islandica has been recognized for more than a decade as a potentially important marine geochemical biorecorder owing to this species great longevity 200 years and wide geographic distribution throughout the northern north atlantic ocean a region vital to global climate and ocean circulation however until now this potential has not been realized owing to the difficulty of precisely sampling the shell of this slow growing species using newly available automated microsampling techniques combined with micromass stable isotope mass spectrometry a stable oxygen isotope record 1956 1957 and 1961 1970 has been obtained from a live captured 38 year old a islandica specimen collected near the former position of the nantucket shoals lightship 41 n 69 w the shell s 18o signal is compared with an expected signal derived from ambient bottom temperature and salinity data recorded at the lightship for the same period the results show that a islandica s 18o record 1 is in phase with its growth banding confirming the annual periodicity of this species growth bands 2 is in oxygen isotopic equilibrium with the ambient seawater 3 shows a consistent shell growth shutdown temperature of 6 c which translates into an 8 month may december shell growth period at this location and 4 records the ambient bottom temperature with a precision of 1 2 c these results add important information on the life history of this commercially important shellfish species and demonstrate that a islandica shells can be used to reconstruct inter and intra annual records of the continental shelf bottom temperature

strontium magnesium and barium incorporation in aragonitic shells of juvenile arctica islandica insights from temperature controlled experiments abstract in order to constrain spatial and temporal temperatures and environmental conditions in the north atlantic ocean during the holocene high resolution seasonal to annual marine proxies with excellent chronological constraints are needed the long lived ocean quahog arctica islandica which has the potential to provide a precise annually dated record via crossdating techniques is a fairly well developed and tested marine proxy archive in particular oxygen isotopes derived from a islandica shell carbonate have provided a wealth of information on marine climate and ocean circulation dynamics however shell derived oxygen isotopes are influenced by both the isotopic source water signature covarying with salinity and seawater temperature if seawater isotopic signature is not known temperature reconstructions become challenging thus an independent technique to estimate past seawater temperatures is highly desired however based on previous studies on adult and juvenile clams the utility of elemental ratios in a islandica shell material as environmental proxies remains questionable to further evaluate the influence of seawater temperature on elemental and isotopic incorporation during biomineralization a islandica shells were grown at constant temperatures under two regimes during a 16 week period from march 27 to july 21 2011 at the darling marine center in walpole maine individual juvenile clams were stained with calcein and cultured at 10 30 0 30 c for six weeks after this the clams were again stained with calcein and cultured at 15 00 0 40 c for an additional 9 5 weeks average salinity values were 30 20 0 70 and 30 70 0 70 in the first and second phases of the experiment respectively continuous sampling within and across the temperature conditions from 10 30 c to 15 00 c coupled with the calcein markings provided the ability to place each sample into a precise temporal framework and to establish exact average growth rates for the shells sampled after accounting for changes in the isotopic composition of seawater oxygen isotopes from one sampled shell effectively recorded seawater temperatures during the study and also gave confidence to the temporal fit of the data elemental ratios sr ca mg ca ba ca from five aragonitic shells were determined via laser ablation inductively coupled plasma mass spectrometry sr ca and mg ca data showed little coherence with temperature during the culture experiment including the rapid 5 c increase in seawater temperature however ba ca ratios showed an inverse relationship with seawater temperatures although this relationship was noisy additionally salinity interactions were present during the 15 00 c treatment further highlighting complex incorporation of elements during biomineralization incorporation of sr mg and ba were strongly and variably impacted by growth rates combined the results from these culture experiments demonstrate that sr ca mg ca ba ca ratios in juvenile a islandica shell material are dominated by physiological processes and thus not reliable as environmental proxies

dispersion and nonlinear effects in the 2011 tohoku oki earthquake tsunami this study reveals the roles of the wave dispersion and nonlinear effects for the 2011 tohoku oki earthquake tsunami we conducted tsunami simulations based on the nonlinear dispersive equations with a high resolution source model the simulations successfully reproduced the waveforms recorded in the offshore deep sea and focal areas the calculated inundation area coincided well with the actual inundation for the sendai plain which was the widest inundation area during this event by conducting sets of simulations with different tsunami equations we obtained the followings insights into the wave dispersion nonlinear effects and energy dissipation for this event although the wave dispersion was neglected in most studies the maximum amplitude was significantly overestimated in the deep sea if the dispersion was not included the waveform observed at the station with the largest tsunami height 2 m among the deep ocean stations also verified the necessity of the dispersion it is well known that the nonlinear effects play an important role for the propagation of a tsunami into bays and harbors additionally nonlinear effects need to be considered to accurately model later waves even for offshore stations in particular including nonlinear terms rather than the inundation was more important when precisely modeling the waves reflected from the coast

postglacial tectonics of the scottish glacio isostatic uplift centre new evidence combined with a detailed re evaluation of postglacial fault movements seismic activity and shoreline sequences suggests that the period of deglaciation and the early holocene was more seismically active than the mid to late holocene it is proposed that the large scale lateral displacements formerly proposed can not be justified rather all postglacial fault movements appear to be limited to metre scale vertical movements along pre existing fault lines in addition it is argued that the younger dryas ice advance may have produced localised crustal redepression but not the more widespread impact formerly proposed both tectonic and postglacial rebound stresses however may be needed to explain the contemporary seismotectonics of the scottish highlands

importance of horizontal seafloor motion on tsunami height for the 2011 mw 9 0 tohoku oki earthquake abstract it is now clear that the 2011 tohoku oki earthquake ruptured the subduction interface all the way to the japan trench however there is significant disagreement about just how much slip occurred at the trench with most geodetic studies locating only a small fraction of the maximum slip there whereas broadband seismic studies put the majority of the slip near the trench measurements of seafloor displacement near the trench also imply more slip there than is estimated by the geodetic studies here by means of a joint inversion of displacement measurements and seafloor pressure data we show that it is possible to reconcile geodetic and seismic studies and that a considerable amount of slip indeed occurred at the trench with slip magnitudes reaching 57 74 of the maximum slip the seafloor displacement predicted by our model agrees very well with independent measurements made close to the trench we also find good agreement between our tsunami model and independent measurements of tsunami height in the ocean and on land re running of the inversion without the near field pressure gauge data however leads to underprediction of the flooding on land even when the seafloor geodetic data are still included thus even if the seafloor geodetic measurements had been available in real time they would still not have allowed reliable prediction of near field tsunami inundation close to the trench the dip of the plate interface is shallow which serves to decrease the vertical motion of the sea floor for any given slip however the horizontal motion is conversely larger because the ocean floor slopes steeply near the trench it acted like a giant wedge converting the horizontal motion of the ground into an uplift of the water column and causing the peak initial tsunami wave height to be twice as high as it would have been from vertical displacement alone

tsunami source of the 2011 tohoku oki earthquake japan inversion analysis based on dispersive tsunami simulations 1 the large tsunami of the 2011 tohoku oki earthquake was clearly recorded by the ocean bottom pressure and gps wave gauges deployed in and around japan we estimated the initial tsunami water height distribution by inversion analysis of the waveforms based on dispersive tsunami simulations the distribution is characterized by a peak height of 8 m located near the trench and the high water 2m region extending landward with a width of 100 km a series of numerical simulations suggests that a relatively steep peak located near the trench is necessary in order to simultaneously reproduce the dispersive wave at a far field station and the near field waveforms furthermore we estimated the coseismic slip distribution at the plate boundary which indicates that large slip 30 m occurred at a depth of 20 km which corresponds to a large slip deficit area in the interseismic period another slip 25 m occurred at the shallower part 10 km during the rupture

tsunami waveform inversion including dispersive waves the 2004 earthquake off kii peninsula japan 1 long waves are often assumed to model tsunamis but the wavelength of the initial water height distribution produced by a large submarine earthquake particularly in the direction perpendicular to the fault strike is sometimes not much greater than the water depth the resulting tsunami may have a dispersive character that cannot be simulated based on a conventional long wave approximation the 2004 earthquake off kii peninsula m 7 4 on the southern coast of japan indeed produced a dispersive tsunami that was recorded at two stations located off shikoku for the foreshock m 7 1 on the contrary a dominant dispersive tsunami was not recognized at these stations because dispersive waves show strong directional dependence with respect to the fault strike the above difference indicates that the strikes of the main shock and the foreshock were different we conducted a tsunami waveform inversion analysis based on the dispersive tsunami equations to estimate the initial water height distribution of the main shock the estimated initial water height distribution overlapped with the aftershock region suggesting that the fault strike was perpendicular to the trough axis and the total displaced water volume was 1 7 2 0 109 m3 when we used the conventional long wave approximation the estimated initial water height distribution extended considerably from the aftershock area because artificial sources were needed outside the aftershock area to reproduce the observed dispersive waves

dispersive modeling of the 2009 samoa tsunami 1 in this study we investigate the dispersive effects in the 2009 samoa tsunami through numerical simulations the wave propagation is first simulated with a weakly nonlinear and dispersive boussinesq model and a non dispersive shallow water equations model comparison of the numerical results between these models indicates that tsunami propagation is significantly affected by the frequency dispersion east of tonga trench neglecting dispersive effects results in larger wave heights and speeds the strong frequency dispersion is primarily attributed to the dramatic variation of water surface elevations generated by the earthquake doublet and enhanced by the uneven bathymetry in tonga trench tsunami propagation is also simulated with most method of splitting tsunamis which is based on the shallow water equations but uses numerical dispersion to mimic physical frequency dispersion at operational resolutions a good agreement is observed between most and the boussinesq model as well as the field measurements in the leading wave in the shorter trailing waves agreement becomes poorer due to the mismatch between numerical and physical dispersions

exploring the calcium isotope signature of arctica islandica as an environmental proxy using laboratory and field cultured specimens abstract the calcium isotope composition 44 40ca of the aragonitic bivalve arctica islandica grown in laboratory and field cultures was investigated in terms of environmental and biological controls to explore its potential as a palaeoceanographic proxy while we found no significant effect of salinity on ca isotope fractionation the relationship between 44ca 40ca ratios of a islandica and temperature was best explained by a generalised additive model which describes the temperature versus ca isotope relationship as a nonlinear second degree polynomial with an optimum temperature of 15 c since 44ca 40ca ratios clearly increase with increasing temperature up to 15 c the temperature versus ca isotope relation can be approximated through a linear fit up to 15 c the slope of this linear temperature dependent ca isotope fractionation resembles previous calibrations of inorganic and biogenic aragonites providing insights into fractionation processes during bivalve biomineralization our findings suggest that the observed biologically induced ca isotope fractionation occurs when ca is transported from seawater to the site of mineralization most likely during the passage through the epithelial mantle the observed evidence for strong vital effects indicates limited use of ca isotopes in a islandica as a temperature proxy

frontal wedge deformation near the source region of the 2011 tohoku oki earthquake 1 we report an uplift of 5 m with a horizontal displacement of more than 60 m due to the 2011 tohoku oki earthquake the uplift was measured by an ocean bottom pressure gauge installed before the earthquake on a frontal wedge which formed an uplift system near the japan trench horizontal displacements of the frontal wedge were measured using local benchmark displacements obtained by acoustic ranging before and after the earthquake the average displacements at the frontal wedge were 58 m east and 74 m east southeast these results strongly suggest a huge coseismic slip beneath the frontal wedge on the plate boundary the estimated magnitude of the slip along the main fault was 80 m near the trench our results suggest that the horizontal and vertical deformations of the frontal wedge due to the slip generated the tremendous tsunami that struck the coastal area of northeastern japan

survey of 2011 tohoku earthquake tsunami inundation and run up 1 at 14 46 local time on march 11 2011 a magnitude 9 0 earthquake occurred off the coast of northeast japan this earthquake generated a tsunami that struck japan as well as various locations around the pacific ocean with the participation of researchers from throughout japan joint research groups conducted a tsunami survey along a 2000 km stretch of the japanese coast more than 5300 locations have been surveyed to date generating the largest tsunami survey dataset in the world on the sendai plain the maximum inundation height was 19 5 m and the tsunami bore propagated more than 5 km inland along the ria coast from about 50 to 200 km north of sendai the narrow bays focused the tsunami waves generating the largest inundation heights and run ups the survey data clearly show a regional dependence of tsunami characteristics

volcanic eruption of the mid ocean ridge along the east pacific rise crest at 9 45 52 n direct submersible observations of seafloor phenomena associated with an eruption event in april 1991 in april 1991 we witnessed from the submersible alvin a suite of previously undocumented seafloor phenomena accompanying an in progress eruption of the mid ocean ridge on the east pacific rise crest at 9 45 n 52 n the volume of the eruption could not be precisely determined although comparison of pre and post eruption seabeam bathymetry indicate that any changes in ridge crest morphology resulting from the eruption were 10 m high effects of the eruption included 1 increased abundance and redistribution of hydrothermal vents disappearance of numerous vent communities and changes in characteristics of vent fauna and mineral deposits within the eruption area since december 1989 2 murkiness of bottom waters up to tens of meters above the seafloor due to high densities of suspended mineral and biogenic particulates 3 destruction of a vent community by lava flows mass wasting and possible hydrovolcanic explosion at a site known as tubeworm barbecue in the axial summit caldera asc at 9 50 6 n 4 near critical temperatures of hydrothermal vent fluids ranging up to 403 c 5 temporal variations over a 2 week interval in both temperatures and chemical isotopic compositions of hydrothermal fluids 6 unusual compositions of end member vent fluids with ph values ranging to a record low of 2 5 salinities ranging as low as 0 3 wt nacl one twelfth that of seawater and dissolved gases reaching high concentrations 65 mmol l for both co2 and h2s 7 venting at temperatures above 380 c of visually detectable white vapor that transformed to plumes of gray smoke a few centimeters above vent orifices 8 disorganized venting of both high temperature fluids black and gray smoke and large volumes of cooler diffuse hydrothermal fluids directly from the basaltic seafloor rather than from hydrothermal mineral constructions 9 rapid and extensive growth of flocculent white bacterial mats species unknown on and under the seafloor in areas experiencing widespread venting of diffuse hydrothermal fluid and 10 subseafloor downslope migration of magma normal to the ridge axis in a network of small scale 1 5 m diameter lava tubes and channels to distances at least 100 200 m outside the asc we suggest that in april 1991 intrusion of dikes in the eruption area to 200 m beneath the asc floor resulted in phase separation of fluids near the tops of the dikes and a large flux of vapor rich hydrothermal fluids through the overlying rubbly cavernous lavas low salinities and gas rich compositions of hydrothermal fluids sampled in the eruption area are appropriate for a vapor phase in a seawater system undergoing subcritical liquid vapor phase separation boiling and phase segregation hydrothermal fluids streamed directly from fissures and pits that may have been loci of lava drainback and or hydrovolcanic explosions these fissures and pits were lined with white mats of a unique fast growing bacteria that was the only life associated with the brand new vents the prolific bacteria which covered thousands of square meters on the ridge crest and were also abundant in subseafloor voids may thrive on high levels of gases in the vapor rich hydrothermal fluids initially escaping the hydrothermal system white bacterial particulates swept from the seafloor by hydrothermal vents swirled in an unprecedented biogenic blizzard up to 50 m above the bottom the bacterial proliferation of april 1991 is likely to be a transient bloom that will be checked quickly either by decline of dissolved gas concentrations in the fluids as rapid heat loss brings about cessation of boiling and or by grazing as other organisms are re established in the biologically devastated area

an evaluation of mg ca sr ca and ba ca ratios as environmental proxies in aragonite bivalve shells the influence of salinity and water chemistry on mg ca sr ca and ba ca ratios in the aragonitic shells of the manila clam was investigated clams were reared at constant temperature 20 c under different controlled conditions of salinity commonly encountered in their natural habitat clams were held in three tanks with a constant salinity of 35 for the first 35days and then two tanks were changed to lower salinities 20 and 28 for the next 29days individual shell mg ca sr ca and ba ca ratios were studied through time despite stable conditions temperature salinity and mg cawater for clams reared at salinity 35 during the experiment mg ca shell ratios increased through the time moreover the salinity decrease at t35 slowed the increase of mg ca shell ratios at salinity 28 and resulted in an mg cashell decrease at salinity 20 despite similar mg cawater ratios in the different salinity treatments microprobe analyses illustrate that mg varies along contemporaneous growth lines the variable shell mg ca ratios suggest that incorporation of magnesium into shell carbonate is strongly regulated by the organism and not by environmental conditions interestingly microprobe analyses illustrated that mg was not associated with shell sulfur as other studies have suggested sr ca shell ratios of clams reared at salinity 35 and under constant conditions were also not as constant as expected if sr ca ratios were an environmental proxy there was an inverse correlation between shell sr ca and salinity despite a slight positive correlation between salinity and sr ca ratios of the water indicating that sr ca ratios do not reflect environmental conditions a strong inverse correlation between salinity and ba ca shell ratios and a positive correlation between ba ca shell and ba ca water was observed therefore ba ca shell ratios seem to be a promising proxy of high resolution 1day salinity variations in estuarine waters via the relationship between ba ca water and salinity this study clearly illustrates that both mg ca and sr ca ratios in aragonite shells are not under environmental control and that ba ca ratios are with the later tracking high resolution water ba ca ratios and hence estuarine salinity variations

time and space distribution of coseismic slip of the 2011 tohoku earthquake as inferred from tsunami waveform data a multiple time window inversion of 53 high sampling tsunami waveforms on ocean bottom pressure global positioning system coastal wave and tide gauges shows a temporal and spatial slip distribution during the 2011 tohoku earthquake the fault rupture started near the hypocenter and propagated into both deep and shallow parts of the plate interface a very large slip approximately 25 m in the deep part off miyagi at a location similar to the previous 869 jogan earthquake model was responsible for the initial rise of tsunami waveforms and the recorded tsunami inundation in the sendai and ishinomaki plains a huge slip up to 69 m occurred in the shallow part near the trench axis 3 min after the rupture initiation this delayed shallow rupture extended for 400 km with more than a 10 m slip at a location similar to the 1896 sanriku tsunami earthquake and was responsible for the peak amplitudes of the tsunami waveforms and the maximum tsunami heights measured on the northern sanriku coast 100 km north of the largest slip the average slip on the entire fault was 9 5 m and the total seismic moment was 4 2 1022 n m m w 9 0 the large horizontal displacement of seafloor slope was responsible for 20 40 of tsunami amplitudes the 2011 deep slip alone could reproduce the distribution of the 869 tsunami deposits indicating that the 869 jogan earthquake source could be similar to the 2011 earthquake at least in the deep plate interface the large tsunami at the fukushima nuclear power station is due to either the combination of a deep and shallow slip or a triggering of a shallow slip by a deep slip which was not accounted for in the previous tsunami hazard assessments online material table of estimated slip for all subfaults at 0 5 min invervals

clams as recorders of ocean ridge volcanism and hydrothermal vent field activity the clam calyptogena magnifica lives at abyssal depths in association with hydrothermal venting on midocean ridges analysis of strontium calcium ratios in c magnifica shells provides a temperature proxy with submonthly time resolution a 21 year strontium calcium record of two clams from 9 50 n on the east pacific rise captures the known 1991 and 1992 eruptive events documents several additional events between 1992 and 1996 and demonstrates the absence of major hydrothermal episodes during the period 1974 to 1991 these clam archives can increase our understanding of the thermal and chemical history of midocean ridge hydrothermal and volcanic activity on decadal time scales

a model of subaqueous sedimentation at the margin of the late midlandian irish ice sheet connemara ireland and its implications for regionally high isostatic sea levels abstract the geomorphology and sedimentology of a series of late midlandian glacigenic sites in connemara western ireland are described and a set of commonly occurring sedimentary assemblages identified these form components of a simple model of ice contact subaqueous sedimentation involving progressive down current transition from subglacial esker tunnel fill through proximal tunnel mouth fans proximal and distal subaqueous fans into basin floor sediments in two of the sites aggradation to the water line passes into fan delta topsets and foresets all sites abut into inferred water bodies to their west and imply minimum water surface heights of between 35 and 65 m irish od or in the case of the two deltaic sites shoreline heights of between 75 and 80 m these high water levels very close to and facing directly into the immediately adjacent open atlantic ocean are difficult to explain as ice dammed glaciolacustrine water bodies without invoking improbable ice sheet marginal geometries they may however be explained as a set of successive fjord head grounding line depositional systems that trace temporary still stands in the phased retreat of the irish ice sheet from its offshore maximum this possibility not yet confirmed by the discovery of in situ marine fauna implies a degree of late midlandian isostatic depression and subsequent response unexplained by currently applied crustal response models but supported by previously constructed glacio sedimentary models

source model of the great 2011 tohoku earthquake estimated from tsunami waveforms and crustal deformation data the slip distribution of the 11 march 2011 tohoku earthquake is inferred from tsunami waveforms gps data and seafloor crustal deformation data the major slip region extends all the way to the trench and the large slip area extends 300 km long and 160 km wide the largest slip of 44 m is located up dip of the hypocenter the large slip amount about 41 m ruptured the plate interface near the trench the seismic moment calculated from the estimated slip distribution is 5 5 10 22 n m mw 9 1 the large tsunami due to the 2011 tohoku earthquake is generated from those large slip areas near the trench the additional uplift at the sedimentary wedge as suggested for the 1896 sanriku earthquake may have occurred during the 2011 tohoku earthquake too

numerical simulation of the 2011 tohoku tsunami based on a new transient fem co seismic source comparison to far and near field observations in this work we simulate the 2011 m9 tohoku oki tsunami using new coseismic tsunami sources based on inverting onshore and offshore geodetic data using 3d finite element models fem such fems simulate elastic dislocations along the plate boundary interface separating the stiff subducting pacific plate from the relatively weak forearc and volcanic arc of the overriding eurasian plate due in part to the simulated weak forearc materials such sources produce significant shallow slip several tens of meters along the updip portion of the rupture near the trench to assess the accuracy of the new approach we compare observations and numerical simulations of the tsunami s far and near field coastal impact for i one of the standard seismic inversion sources ucsb shao et al 2011 and ii the new fem sources specifically results of numerical simulations for both sources performed using the fully nonlinear and dispersive boussinesq wave model funwave tvd are compared to dart buoy gps tide gauge and inundation runup measurements we use a series of nested model grids with varying resolution down to 250 m nearshore and size and assess effects on model results of the latter and of model physics such as when including dispersion or not we also assess the effects of triggering the tsunami sources in the propagation model i either at once as a hot start or with the spatiotemporal sequence derived from seismic inversion and ii as a specified surface elevation or as a more realistic time and space varying bottom boundary condition in the latter case we compute the initial tsunami generation up to 300 s using the non hydrostatic model nhwave although additional refinements are expected in the near future results based on the current fem sources better explain long wave near field observations at dart and gps buoys near japan and measured tsunami inundation while they simulate observations at distant dart buoys as well or better than the ucsb source none of the sources however are able to explain the largest runup and inundation measured between 39 5 and 40 25 n which could be due to insufficient model resolution in this region sanriku ria of complex bathymetry topography and or to additional tsunami generation mechanisms not represented in the coseismic sources e g splay faults submarine mass failure this will be the object of future work

direct energy estimation of the 2011 japan tsunami using deep ocean pressure measurements 1 we have developed a method to compute the total energy transmitted by tsunami waves to the case where the earthquake source is unknown by using deep ocean pressure measurements and numerical models tsunami source functions based on the first wave recorded at the two closest tsunameters deep ocean assessment and reporting of tsunamis dart our analysis suggests that the march 11 2011 tohoku oki tsunami generated off japan originated from a 300 400 km long and 100 km wide area and the total propagated energy is 3 1015j with 6 uncertainty measurements from 30 tsunameters and 32 coastal tide stations show excellent agreement with the forecasts obtained in real time our study indicates that the propagated energy and the source location are the most important source characteristics for predicting tsunami impacts interactions of tsunami waves with seafloor topography delay and redirect the energy flux posing hazards from delayed and amplified waves with long duration seafloor topography also gives its spectral imprint to tsunami waves travel time forecast errors are path specific and correlated to the major wave scatterers in the pacific numerical dissipation in the propagation modeling highlights the need of high resolution inundation models for accurate coastal predictions on the other hand it also can be used to account for physical dissipation to achieve efficiency our results provide guidelines for the earliest reliable tsunami forecast warnings of long duration tsunami waves signals and enhancement of the experimental tsunami forecast system we apply the method to quantify the energy of 15 past tsunamis independently from earthquake magnitudes the small tsunami to seismic radiation energy ratios and their variability 0 01 0 8 reinforce the importance of using deep ocean tsunami data the direct measures of tsunamis for estimates of tsunami energy and accurate forecasting

three dimensional simulation of tsunami generation and propagation application to intraplate events 1 a parallel finite difference numerical simulation program based on the navier stokes ns equations is developed for simulating 3 d tsunami generation and propagation we can simulate tsunami propagation over more than 1000 km using this program although such tsunami propagation over long distances has usually been conducted on the basis of on 2 d simulations some 2 d simulations have assumed that the initial tsunami distribution is identical to the sea bottom deformation caused by the earthquake the 3 d simulations however indicate that this assumption is inappropriate when the source width 2ax is less than 10 times the sea depth h 2ax 10h for a source process time of 20 s dispersion of tsunami appears when the source is of small size and the dispersion is more apparent in a direction perpendicular to the fault strike we also conduct tsunami simulations for two intraplate events the 2004 off kii peninsula m 7 4 and the 2007 off kuril islands m 8 1 events the 3 d tsunami simulation has successfully simulated the offshore tsunami and we obtained good agreement between the observations and the calculations for both events in particular for the 2004 off kii peninsula event although the 2 d linear long wave theory cannot simulate important characteristics in the record such as the arrival time of the peak amplitude and the dispersive tsunami the 3 d ns simulation is well able to model those characteristics

chemistry of ore forming fluids and mineral formation rates in an active hydrothermal sulfide deposit on the mid atlantic ridge the chemical composition of diffuse effluent from the tag hydrothermal mound 26 n mid atlantic ridge directly demonstrates that mixing of entrained seawater and high temperature black smoker fluids leads to the precipitation of sulfides silica and anhydrite and to the zone refining of metals including cu zn u and the rare earth elements in an actively forming sulfide ore body rates of mineral formation deduced from these data are extremely rapid and are up to an order of magnitude greater for anhydrite 5 15 107 kg yr than for sulfides 106 107 kg yr comparison with mineral inventories for tag suggests that virtually all of the anhydrite in the tag mound is contemporary and confirms that the sulfide precipitated episodically during the history of mound growth and that much of it has been lost by oxidation and reworking