sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

rupture process of the 2011 tohoku oki mega thrust earthquake m9 0 inverted from strong motion data 1 we investigate the rupture process of the m9 0 tohoku oki mega thrust earthquake using the relatively low frequency strong motion records 0 01 0 125 hz observed at 36 k net and kik net stations the epicentral distances of which range from 120 km to 400 km the fault model is a rectangular plane the length and width of which are 510 km along the japan trench and 210 km along subducting direction of the pacific plate respectively we perform the multi time window inversion analysis with a 30 30 km2 subfault the derived slip model has one large slip area this area extends from the region around the hypocenter to the shallow part of the fault plane and further to the north and south along the trench axis located far off southern iwate miyagi and northern fukushima prefectures the seismic moment is 4 42 1022 nm mw 9 0 and the maximum slip is 48 m the slips near the coast are relatively small except off miyagi prefecture which experienced a slip greater than 5 m the shallow large slip area which continuously ruptured from 60 s to 100 s after the initial break radiated seismic waves rich in very low frequency content 0 02 hz the rupture after 100 s propagating to the southern fault area contributes to the distinct phases observed for fukushima and ibaraki prefectures the relationship between the proposed rupture model and the feature of the acceleration waveforms is not straightforward and suggests the frequency dependency of the seismic wave radiation

relationships between heavy metals distribution and organic matter cycling in mangrove sediments conception bay new caledonia mangroves of new caledonia act as a buffer between a lagoon of more than 20 000 km2 and the island which suffers intense processes of erosion resulting from urbanization and natural resources exploitation this preliminary study aims at determining how heavy metals are distributed in mangrove sediments and pore waters in relationship with their organic content to reach our goal a series of 50 cm deep cores were collected in the mangrove of conception bay the various coring sites are representative of live forests avicennia marina rhizophora stylosa dead forest and intertidal unvegetated area the ranges of concentrations in sediments were the following mol g 1 cu 0 08 to 0 51 co 0 01 to 0 38 ni 0 03 to 3 55 cr 0 36 to 3 11 zn 0 68 to 2 36 mn 1 13 to 5 0 and fe 22 64 to 721 69 heavy metals distribution within sediments and pore water appear to result from diagenetic processes linked to om decomposition beneath the dead avicennia forest and in the unvegetated sediments the higher the organic content the higher the metal concentration in the solid phase beneath living mangrove stands despite a higher organic content as well as higher sulphur content heavy metals concentrations were not higher than those measured in the other sampling sites beneath these forests redox conditions were mainly controlled by the length of waterlogging and the activity of root system we suggest that because of the specificity of the avicennia root system and its position in the intertidal zone heavy metals are more bioavailable and potentially more mobile than beneath rhizophora stand

finite faults and inverse theory with applications to the 1979 imperial valley earthquake abstract using a representation theorem from elastodynamics subsurface slip on a known fault is formulated as the solution to an inverse problem in which recorded surface ground motion is the data two methods of solution are presented the least squares method which minimizes the squared differences between theory and data and the constrained least squares method which simultaneously maintains a set of linear inequalities instabilities in the solution are effectively eliminated in both methods and the sensitivity of the solution to small changes in the data is quantitatively stated the inversion methodology is applied to 77 components of near field ground acceleration recorded during the 15 october 1979 imperial valley earthquake the faulting is constrained to propagate bilaterally away from the epicenter at an average velocity of 90 per cent of the shear wave speed on a vertical fault plane extending from the surface to 10 km depth inequality constraints are used to keep the faulting sequence physically reasonable by maintaining right lateral motion and positive slip velocity the preferred solution is stable and provides a good fit to the data it is also realistic and consistent with observed surface offsets and independent estimates of seismic moment

environmental geochemistry of core sediments from serthalaikkadu creek east coast of india the serthalaikkadu creek in muthupet mangroves region is the only e w trending coastal strip in the se coast of india and it also acts as a barrier to natural disasters natural anthropogenic signals and accumulation of elements were studied by collecting sediments from two cores textural parameters were studied in detail and carbonates caco3 organic carbon oc major si al fe na k ca mg p and trace elements mn cr cu ni co pb zn were determined textural parameters caco3 oc and al normalized pattern of elements indicate depositional events in core samples that can be directly related to natural events during the last decade the calculated enrichment anthropogenic factors and comparison of data indicate that the observed trace metals especially pb co are enriched mainly due to the anthropogenic activities in the land as well as in the coastal zone palk strait

solar cycle variations in polar cap area measured by the superdarn radars 1 we present a long term study from january 1996 to august 2012 of the latitude of the heppner maynard boundary hmb measured at midnight using the northern hemisphere super dual auroral radar network superdarn the hmb represents the equatorward extent of ionospheric convection and is used in this study as a measure of the global magnetospheric dynamics we find that the yearly distribution of hmb latitudes is single peaked at 64 magnetic latitude for the majority of the 17 year interval during 2003 the envelope of the distribution shifts to lower latitudes and a second peak in the distribution is observed at 61 the solar wind magnetosphere coupling function derived by milan et al 2012 suggests that the solar wind driving during this year was significantly higher than during the rest of the 17 year interval in contrast during the period 2008 2011 hmb distribution shifts to higher latitudes and a second peak in the distribution is again observed this time at 68 magnetic latitude this time interval corresponds to a period of extremely low solar wind driving during the recent extreme solar minimum this is the first long term study of the polar cap area and the results demonstrate that there is a close relationship between the solar activity cycle and the area of the polar cap on a large scale statistical basis

geochemistry of core sediments from mullipallam creek south east coast of india the mullipallam creek in muthupet mangroves region is the only e w trending coastal strip in the se coast of india and is very important as the mangrove acts as a barrier to natural diasters natural anthropogenic signals and accumulation of elements were made by collecting sediment samples at various depths in a core all sediments were analyzed for carbonates caco3 organic carbon oc major si al fe na k ca mg p and trace mn cr cu ni co pb zn normalization with al values has been done for all the major and trace elements and enrichment factors have been calculated the calculated enrichment factors and comparison indicate that the trace metals especially pb are enriched mainly due to the external anthropogenic activities in the land as well as in the coastal zone palk strait

the partitioning of transitional metals fe mn ni cr in mangrove sediments downstream of a ferralitized ultramafic watershed new caledonia abstract in new caledonia one third of the island is composed of ultramafic rocks and lateritic soils enriched in fe ni and cr open cast mining occurs all around the island and processes of erosion and sedimentation which occur naturally along the coastline are strongly amplified by mining activities due to their position at the interface between land and sea mangroves receive extensive amounts of particles emanating from rivers through estuaries the purpose of this study is to understand the distribution and partitioning of some transitional metals fe mn ni cr in sediments and pore waters in a mangrove swamp which is situated downstream of a catchment characterized by lateritic soils that were exploited a century ago quantitative analyses on bulk and after selective extraction were carried out on cores collected along a transect within the intertidal zone i e beneath a rhizophora stylosa stand an avicennia marina stand and within a salt flat mean metal concentrations were mol g 1 fe 1997 ni 44 2 cr 31 9 mn 8 8 thus ni cr and fe concentrations in this study are substantially higher than mangrove world average in addition ni concentrations are 10 to 100 times higher than in other new caledonian mangrove developing downstream of a catchment not composed of ultramafic rocks the studied mangrove is characterized by gradients of water and organic contents with depth and along the intertidal zone which induced different redox conditions and thus different metals partitioning transitional metals are deposited in the mangrove mainly as oxides and or oxy hydroxides that are subsequently dissolved by bacteria for the decomposition of organic matter and which leads to a strong increase of metals in the dissolved phase then dissolved metals were precipitated with organic and sulfide compounds to conclude organic diagenesis in mangrove sediments leads to the transfer of transitional metals from oxide form to organic and sulfide forms

anisotropic shear wave velocity structure of the earth s mantle a global model 1 we combine a new large data set of surface wave phase anomalies long period waveforms and body wave travel times to construct a three dimensional model of the anisotropic shear wave velocity in the earth s mantle our modeling approach is improved and more comprehensive compared to our earlier studies and involves the development and implementation of a new spherically symmetric reference model simultaneous inversion for velocity and anisotropy as well as discontinuity topographies and implementation of nonlinear crustal corrections for waveforms a comparison of our new three dimensional model s362ani with two other models derived from comparable data sets but using different techniques reveals persistent features 1 strong 200 km thick high velocity anomalies beneath cratons likely representing the continental lithosphere underlain by weaker fast anomalies extending below 250 km which may represent continental roots 2 weak velocity heterogeneity between 250 and 400 km depths 3 fast anomalies extending horizontally up to 2000 3000 km in the mantle transition zone beneath subduction zones 4 lack of strong long wavelength heterogeneity below 650 km suggesting inhibiting character of the upper mantle lower mantle boundary and 5 slow velocity superplumes beneath the pacific and africa the shear wave radial anisotropy is strongest at 120 km depth in particular beneath the central pacific lateral anisotropic variations appreciably improve the fit to data that are predominantly sensitive to the uppermost and lowermost mantle but not to the waveforms that control the transition zone and midmantle depths tradeoffs between lateral variations in velocity and anisotropy are negligible in the uppermost mantle but noticeable at the bottom of the mantle

a spatial random field model to characterize complexity in earthquake slip 1 finite fault source inversions reveal the spatial complexity of earthquake slip over the fault plane we develop a stochastic characterization of earthquake slip complexity based on published finite source rupture models in which we model the distribution of slip as a spatial random field the model most consistent with the data follows a von karman autocorrelation function acf for which the correlation lengths a increase with source dimension for earthquakes with large fault aspect ratios we observe substantial differences of the correlation length in the along strike a x and downdip a z directions increasing correlation length with increasing magnitude can be understood using concepts of dynamic rupture propagation the power spectrum of the slip distribution can also be well described with a power law decay i e a fractal distribution in which the fractal dimension d remains scale invariant with a median value d 2 29 0 23 while the comer wave number k c which is inversely proportional to source size decreases with earthquake magnitude accounting for larger slip patches for large magnitude events our stochastic slip model can be used to generate realizations of scenario earthquakes for near source ground motion simulations

the composition of sedimentary organic matter in relation to the dynamic features of a mangrove fringed coast in french guiana the sedimentary organic matter content of a series of 2 m deep cores was examined in relation to the evolution of mangrove forest on the basis of geochemical analyses and optical observations avicennia dominated forest deposits developing along the highly dynamic coastline of french guiana were collected in five stations based on stage of forest evolution the sedimentary organic matter in the upper sediment of the youngest mangrove swamp is mainly derived from algal mats with low carbon nitrogen ratios c n ratio from 6 to 8 and typical greyish amorphous organic flakes as observed in optical studies indeed rare young avicennia trees are present and effectively geochemical parameters do not give evidence of a litter made up of higher plant debris these rare debris being probably exported by the tides a slight increase with depth in the first decimetres of both total organic carbon toc content and c n ratio results from the development of the radial cable root system of the pioneer avicennia germinans early diagenetic conditions of this young forest are rather controlled by dominant suboxic processes as suggested by high eh values range 200 400 mv and local anoxic processes occurrence of pyrite in micro environments this is mainly due to the oxygen available by roots and crab bioturbation the organic content of the senescent mangrove sediment is mainly derived from higher plant debris in the uppermost 30 cm as indicated by relatively high c n ratios and the predominance of ligno cellulosic debris the strong decrease in hydrogen index values results from the degradation of the higher plant debris losing hydrogen bounds through decay processes moderately acidic ph values low ehs and the presence of pyrite framboids point towards the reducing decay processes in surficial layers of the senescent mangrove mediated by sulphate reducing bacteria whatever the stage of evolution of the forest the geochemical characteristics of the sediment below 30 cm are those of the shoreface one with opaque refractory debris derived from the amazon river detritus discharge the sediment collected from dead mangrove forests subsequently recolonized by pioneer mangroves contains organic markers which predate recolonization recording previous phases of erosion and accretion

the dynamics of estuarine manganese cycling seasonal observations of dissolved managnese in the tamar estuary south west england have demonstrated pronounced temporal and spatial variability in the distribution of this component simultaneous observations of physical and physico chemical properties of the estuarine system together with kinetic measurements of dissolved managenese behaviour in isolated samples have demonstrated that the observed distributions are the instantaneous product of dynamic interactions involving external sources and internal input and removal processes dissolved manganese is mobilized internally from reduced sedimentsduring advective resuspension of bed material so that this input is regulated by temporal and spatial variations in tidal stress manganese is returned to the sediments by continuous uptake on to suspended particles the rate of this process is responsive to changes in suspended particulate load ionic strength ph and temperature the reaction changes from zero order kinetics in freshwater to first order kinetics characteristic of the saline medium with marked deceleration in effective removal rate following small increases in salt concentration relative changes in the first order removal rate throughout the estuary are consistent but there are considerable temporal variations in the absolute rates this is partially attributable to variations in the quality as well as the quantity of the suspended particles these results indicate that changes in the relative effectiveness of both the input and removal mechanisms which lead to internal cycling of manganese and to variable distributions of dissolved managanese within the estuary are closely coupled to the internal behaviour of particles and hence to the tidally induced oscillations in bed stress this observation has been confirmed by sequential recordings of dissolved manganese distributions through a spring tide to neap tide period furthermore climatic events producing enhanced disturbance of bed sediment have been shown to induce a similar sequence of events to that arising from tidally induced net mobilization of bed material

tracing of anthropogenic zinc sources in coastal environments using stable isotope composition abstract the use of zinc isotopes to trace anthropogenic sources in coastal areas has been tested in this study we determined the stable isotopic composition of zinc in sediment cores suspended particulate matter spm and rocks collected at the sepetiba bay southeastern brazil an estuarine lagoon heavily impacted by metallurgic activities these isotopic signatures were compared with those from willemite ore which represent the main mineral refined by the major industrial source of zinc the aim was to test if this tracer system enables to identify sources and sinks of anthropogenic zinc and to reconstruct the temporal and spatial evolution of zinc contamination the zinc isotopic compositions expressed using the 66zn notation relative to the jmc 3 0749 l solution showed significant variations in the sediment cores the spm and willemite ore minerals ranging between 0 01 and 1 15 spatial and temporal analysis of sediments samples fit well in a model of mixing involving three main end members i terrestrial background 66znjmc 0 28 0 12 2 ii marine detrital material 66znjmc 0 45 0 03 2 and iii a major anthropogenic source associated with electroplating wastes released into the bay 66znjmc 0 86 0 15 2 sediment cores collected in the mud flats showed high correlation between 66zn and zinc enrichment factors suggesting good preservation of the isotopic records of natural and anthropogenic sources the sediment core sampled from a mangrove wetland located in a zone impacted by the metallurgy presented levels of zinc up to 4 sediment dry weight and preserved the isotopic signatures of electroplating wastes despite evidences that post depositional processes slightly changed the isotopic signatures in some layers from this core toward heavier 66znjmc values above 1 0 a two component mixing model suggests contributions of this major anthropogenic zn source up to nearly 80 during periods of electroplating activities our work suggests that zn isotope compositions of sediments are reliable tracers of anthropogenic sources and therefore can be useful to improve environmental monitoring efforts in coastal systems

rupture process of the 2004 sumatra andaman earthquake the 26 december 2004 sumatra andaman earthquake initiated slowly with small slip and a slow rupture speed for the first 40 to 60 seconds then the rupture expanded at a speed of about 2 5 kilometers per second toward the north northwest extending 1200 to 1300 kilometers along the andaman trough peak displacements reached 15 meters along a 600 kilometer segment of the plate boundary offshore of northwestern sumatra and the southern nicobar islands slip was less in the northern 400 to 500 kilometers of the aftershock zone and at least some slip in that region may have occurred on a time scale beyond the seismic band

teleseismic inversion for rupture process of the 27 february 2010 chile mw 8 8 earthquake the 27 february 2010 chile m w 8 8 earthquake is the fifth largest earthquake to strike during the age of seismological instrumentation the faulting geometry slip distribution seismic moment and moment rate function are estimated from broadband teleseismic p sh and rayleigh wave signals we explore some of the trade offs in the rupture process estimation due to model parameterizations limited teleseismic sampling of seismic phase velocities and uncertainty in fault geometry the average slip over the 81 500 km 2 rupture area is about 5 m with slip concentrations down dip up dip and southwest and up dip and north of the hypocenter relatively little slip occurred up dip offshore of the hypocenter the average rupture velocity is 2 0 2 5 km s

a sporadic third layer in the ionosphere of mars the daytime martian ionosphere has been observed as a two layer structure with electron densities that peak at altitudes between about 110 and 130 kilometers the mars express orbiter radio science experiment on the european mars express spacecraft observed in 10 out of 120 electron density profiles a third ionospheric layer at altitude ranges of 65 to 110 kilometers where electron densities on average peaked at 0 8 10 10 per cubic meter such a layer has been predicted to be permanent and continuous its origin has been attributed to ablation of meteors and charge exchange of magnesium and iron our observations imply that this layer is present sporadically and locally

the great sumatra andaman earthquake of 26 december 2004 the two largest earthquakes of the past 40 years ruptured a 1600 kilometer long portion of the fault boundary between the indo australian and southeastern eurasian plates on 26 december 2004 seismic moment magnitude mw 9 1 to 9 3 and 28 march 2005 mw 8 6 the first event generated a tsunami that caused more than 283 000 deaths fault slip of up to 15 meters occurred near banda aceh sumatra but to the north along the nicobar and andaman islands rapid slip was much smaller tsunami and geodetic observations indicate that additional slow slip occurred in the north over a time scale of 50 minutes or longer

behavior of redox sensitive elements during weathering of granite in subtropical area using x ray absorption fine structure spectroscopy abstract the variation in chemical compositions of regolith along a weathering profile developed on a granite substrate in jiangxi province in southern china was investigated in this paper with the aim to characterize the speciation of redox sensitive elements and to evaluate their mobility and redistribution during chemical weathering mass balance calculations indicate titanium ti is the most immobile element in this weathering profile a new method x ray absorption fine structure xafs spectroscopy was used to determine the speciation of fe and mn along the profile fe k edge x ray absorption near edge structure xanes spectra show fe in saprolith is stabilized mainly in the state of fe iii suggesting fe is as immobile as conservative elements during granite weathering mn k edge xanes spectra show mn iii iv oxides are reduced to mn ii in surface soil where soil organic matter som acts as an important reductant although ce co and v were unable to be analysed by xafs their concentrations have significant correlations with that of mn indicating that the mobilization and redistribution of ce co and v may also be governed by redox condition all in all the results suggest that redox process impacts significantly on the redistribution of mn ce co and v along the profile the successful application of xafs in the study on migration of redox sensitive elements during granite chemical weathering has provided valuable information for the understanding and evaluating the geochemical behavior of elements in the environment

the effect of seasonal rainfall on nutrient input and biological productivity in the yax chen cave system ox bel ha mexico and implications for μxrf core studies of paleohydrology abstract lakes and speleothems from mexico s yucatan peninsula have been used extensively over the past decades for paleoclimate studies however aquifer condition and its response to climate change has received little attention cenotes sinkholes and coastal caves have been shown to record the paleohydrology of the aquifer but there is little information on sedimentation in these cave systems and its response to climate change newly developed xrf instrumentation for the analysis of cores can achieve subannual resolution due to small measurement increments but short period studies examining weathering inputs and rainfall have not yet been undertaken hindering paleoenvironmental interpretations of lake and cave sediment records this study examines the spatial and temporal relationship of cave sediment geochemistry in the anchialine cave system of yax chen quintana roo mexico sediment traps n 51 were placed at seventeen stations along the 2 7 km flooded cave system which transitions from mangrove to upland forest terrain with cenotes of variable size and frequency along its length sediment traps were collected every 6 months from may 2013 may 2017 along with rainfall and groundwater level data there are distinct responses of lithogenic fe ti sr limestone weathering and biogenic influenced si k s phytoplankton and mangrove sediment elements in the sediment samples associated with seasonal rainfall and hurricanes while lithogenic elements ti k show a direct relationship seasonal rainfall the sedimentation of biologically influenced si ti elements exhibit a 6 12 month lagged response with large rainfalls such as hurricane ingrid in 2013 and other tropical storms throughout the study period

pyritization of trace metals in anoxic marine sediments the pyritization of reactive trace elements in different anoxic marine sediments was investigated to determine the importance of factors such as h2s reactive fe pyrite content and salinity in controlling this process the areas studied included anoxic sulfidic sediments baffin bay a hypersaline coastal lagoon from texas and green canyon a hemipelagic oil seepage area anoxic nonsulfidic sediments with high sedimentation rates atchafalaya bay mississippi delta system hemipelagic anoxic nonsulfidic sediments with low sedimentation rates gulf of mexico shelf and slope and orca basin an euxinic hypersaline basin and organic rich marsh sediments atchafalaya bay results indicate that the degree of trace metal pyritization dtmp of all trace metals except cd increased with increasing degree of pyritization dop irrespective of the type of sedimentary environment involved however for as hg and mo the dtmpdop values were generally above the 1 1 ratio line whereas the transition metals co cu mn and ni displayed a close to linear increase in dtmp with dop and moderate incorporation into pyrite chromium and the class b metals pb and zn were also gradually incorporated into the pyrite phase but without reaching the dtmp levels exhibited by the transition metals cadmium was not incorporated to a significant extent these results are consistent with the chemical attributes of these different classes of trace elements availability of dissolved trace metals and organic matter content are apparently important factors controlling the incorporation of co cr cu and ni into pyrite in anoxicsulfidic fe poor and h2s rich environments

redox stratification and heavy metal partitioning in avicennia dominated mangrove sediments a geochemical model abstract mangrove forest sediments can provide a sink for trace metals because the mangroves create a baffle that promotes the accumulation of fine grained organic matter rich sediment which is usually sulphidic due to the presence of sulphate reducing bacteria direct adsorption complexing with organic matter and the formation of insoluble sulphides all contribute to the trapping of metals the concentration and chemical speciation of the metals are influenced by the distribution of geochemically distinct horizons within the sediment in horizons with a ph 7 and an eh 100 mv oxidation horizons most metals are present as exchangeable or oxide bound species in most cores two oxidation and two reduction horizons can be recognised but dark mottles of low eh 100 mv sediment can be found around mangrove roots and burrows in the reduction horizons the depth to each horizon differs between cores and can change in response to seasonal shifts in the position of the water table a model is presented that accounts for the development of the oxidation and reduction horizons within the avicennia dominated mangrove forest sediment and describes the major controls on metal cycling within the sediment

understanding distribution and abundance of metals with space and time in estuarine mudflat sedimentary environment spatial and depth wise distribution of sediment components organic carbon and selected metals fe mn al ni cr co zn and pb is studied across upper and middle tidal flats from lower and middle estuarine regions of kundalika estuary central west coast of india silt and clay form the major components in lower and middle estuary respectively sand silt clay and organic carbon showed band type distribution along the estuary the sediment deposition over the years took place in varying hydrodynamic conditions in lower and middle estuarine regions upper flats of the lower estuary represent mud while middle flats of the lower estuary facilitated the deposition of sandy mud correlation results indicated the importance of clay and organic carbon in removal and trapping of metals at lower and middle estuary respectively factor analysis indicated that the distribution of metals is largely controlled by fe mn oxyhydroxides and organic carbon the middle flats of the lower estuary showed an anthropogenic source for ni cr and co while middle flats of the middle estuary showed a mainly lithogenic source

tsunami forecast by joint inversion of real time tsunami waveforms and seismic or gps data application to the tohoku 2011 tsunami correctly characterizing tsunami source generation is the most critical component of modern tsunami forecasting although difficult to quantify directly a tsunami source can be modeled via different methods using a variety of measurements from deep ocean tsunameters seismometers gps and other advanced instruments some of which in or near real time here we assess the performance of different source models for the destructive 11 march 2011 japan tsunami using model data comparison for the generation propagation and inundation in the near field of japan this comparative study of tsunami source models addresses the advantages and limitations of different real time measurements with potential use in early tsunami warning in the near and far field the study highlights the critical role of deep ocean tsunami measurements and rapid validation of the approximate tsunami source for high quality forecasting we show that these tsunami measurements are compatible with other real time geodetic data and may provide more insightful understanding of tsunami generation from earthquakes as well as from nonseismic processes such as submarine landslide failures

the 2011 magnitude 9 0 tohoku oki earthquake mosaicking the megathrust from seconds to centuries geophysical observations from the 2011 moment magnitude m w 9 0 tohoku oki japan earthquake allow exploration of a rare large event along a subduction megathrust models for this event indicate that the distribution of coseismic fault slip exceeded 50 meters in places sources of high frequency seismic waves delineate the edges of the deepest portions of coseismic slip and do not simply correlate with the locations of peak slip relative to the m w 8 8 2010 maule chile earthquake the tohoku oki earthquake was deficient in high frequency seismic radiation a difference that we attribute to its relatively shallow depth estimates of total fault slip and surface secular strain accumulation on millennial time scales suggest the need to consider the potential for a future large earthquake just south of this event

determination of megathrust rupture processes using plate interface based fault models and 3d green s functions an application to the 2011 mw 9 1 tohoku earthquake in order to understand physical processes of megathrust earthquakes and thus to analyze hazards of the regions proper information of the rupture processes is essential in this study we develop a technique for determination of large spatial scale rupture processes on megathrust faults in subduction zones as soon as possible based on teleseismic broadband full waveform inversions using realistic models of finite fault geometries and 3d global velocity structures finite fault geometry models are constructed for eleven subduction zones of the circum pacific area utilizing the 3d plate interface model slab 1 0 of usgs green s functions for available pairs of subfaults and globally distributed stations to be used in the inversions are computed in the global 3d velocity model using spectral element method rather than in a 1d velocity model this scheme accommodates synthetic waves with lateral velocity variations especially for surface waves which is useful in estimations of large spatial scale slip distributions the data utilized are teleseismic broadband full waveform records including body waves and surface waves at the epicentral distance of 30o 80o the observed data are inverted for fault rupture processes based on the non negative least square technique with a multiple source time window scheme for each subfault the applicability of the method is tested for the 2011 mw 9 0 tohoku oki earthquake and the result shows that the proposed scheme of the finite fault inversion produces reasonable results of slip distributions

a unified source model for the 2011 tohoku earthquake abstract the devastating 2011 tohoku earthquake was observed by dense networks of geophysical instruments a unified source model was constructed through joint inversion of teleseismic strong motion and geodetic datasets the result indicates that the earthquake consists of three main ruptures after small rupture in the initial 50 s the first rupture expanded at a slow speed of 1 8 km s to the northeast and east the second rupture began 20 s later at the slowest speed of 1 5 km s and became dominant with the largest slip of 36 m the third rupture then played the leading role propagating southward at a speed of 2 5 km s only the tsunami inversion requires an extension of the source fault to a shallow part between the first rupture area and the japan trench recovering tsunamigenic slips larger than 40 m the slow rupture speed and tsunamigenic slips can explain the features of the disaster by the earthquake

slip of the 2004 sumatra andaman earthquake from joint inversion of long period global seismic waveforms and gps static offsets the 26 december 2004 great sumatra andaman earthquake opened a new era for seismologists to understand the complex source process of a great earth quake this is the first event with moment magnitude greater than 9 since the de ployment of high dynamic range broadband seismic and global positioning system gps sensors around the globe this study presents an analysis of the ruptured fault plane geometry and slip distribution using long period teleseismic data and gps measured static surface displacements near the fault plane we employ a rupture geometry with six along strike segments with and without a steeper down dip ex tension the fault segments are further subdivided into a total of 201 30 30 km fault patches sensitivity tests of fault plane geometry and the variation in rupture velocity indicate that the dip and curvature of the fault plane are not well resolved from the given data set and the rupture velocity is constrained to be between 1 8 and 2 6 km sec error estimations of the slip distribution using a random selection of seismic and gps station subsets 50 of all stations illustrate that slip is well re solved along the whole rupture and the mean slip uncertainty is less than 1 5 m about 11 although it is possible that near field gps data include contributions from additional postseismic transient deformation our preferred model suggests that the sumatra andaman earthquake had a magnitude of mw 9 20 0 05 0 06 online material comparison of slip models gps modeling waveform fit fault geometry and inversion parameters

exafs analysis of iron cycling in mangrove sediments downstream a lateritized ultramafic watershed vavouto bay new caledonia mangrove forests are the dominant intertidal ecosystem of tropical coastlines in new caledonia mangroves act as a buffer zone between massive fe lateritic deposits and a lagoon partly registered by unesco as a world heritage site the new caledonian mangroves are characterized by a botanical gradient composed of three main vegetal stands i e rhizophora spp avicennia marina and salt flat which relies on the duration of tidal immersion that imposes gradients of pore water salinity oxygenation and organic content in the sediment in the present study we have determined the distribution and speciation of fe in mangrove sediments along this botanical gradient by using x ray absorption spectroscopy xas at the fe k edge both xanes and exafs results show that iron speciation strongly follows the redox boundaries marking the intertidal and depth zonations fe bearing minerals eroded from lateritic outcrops mainly goethite a feooh and phyllosilicates serpentine and talc are the major fe hosts in the upward horizons these mineral species progressively disappear with increasing depth where pyrite fes2 forms in the hydromorphic rhizophora and avicennia zones sulfate reduction is not observed in the drier salt flat zone in addition to these reduction processes intense re oxidation of aqueous fe ii and pyrite leads to the formation of poorly ordered ferrihydrite lepidocrocite c feooh and likely goethite in the upper sediments beneath avicennia and rhizophora stands the relative proportion of the newly formed poorly ordered ferrihydrite and lepidocrocite is found to be higher in the rhizophora mangrove stand which is the closest to the shore tidal fluctuations may thus be a major cause for continuous fe reduction oxidation cycles in the vegetated mangrove stands which could significantly affect the iron mass balance in mangrove systems

geochemistry of iron and manganese in soils and sediments of a mangrove system island of pai matos cananeia sp brazil abstract five zones along a transect of 180 m were selected for study on the island of pai matos sao paulo brazil four of the zones are colonised by vascular plants spartina sp laguncularia lg avicennia av and rhizophora rh and were denominated soils and the other zone which lacks vegetation was denominated sediment sd the geochemical conditions differed significantly in soils and sediment and also at different depths the soils were oxic eh 350 mv or suboxic eh 350 100 mv at the surface and anoxic eh

ni cycling in mangrove sediments from new caledonia abstract covering more than 70 of tropical and subtropical coastlines mangrove intertidal forests are well known to accumulate potentially toxic trace metals in their sediments and thus are generally considered to play a protective role in marine and lagoon ecosystems however the chemical forms of these trace metals in mangrove sediments are still not well known even though their molecular level speciation controls their long term behavior here we report the vertical and lateral changes in the chemical forms of nickel which accumulates massively in mangrove sediments downstream from lateritized ultramafic deposits from new caledonia where one of nature s largest accumulations of nickel occurs to accomplish this we used ni k edge extended x ray absorption fine structure exafs spectroscopy data in combination with microscale chemical analyses using scanning electron microscopy coupled with energy dispersive x ray spectroscopy sem edxs after principal component and target transform analyses pca tt the exafs data of the mangrove sediments were reliably least squares fitted by linear combination of 3 components chosen from a large model compound spectral database including synthetic and natural ni bearing sulfides clay minerals oxyhydroxides and organic complexes our results show that in the inland salt flat ni is hosted in minerals inherited from the eroded lateritic materials i e ni poor serpentine 44 58 ni rich talc 20 31 and ni goethite 18 24 in contrast in the hydromorphic sediments beneath the vegetated avicennia and rhizophora stands a large fraction of ni is partly redistributed into a neoformed smectite pool 20 69 of ni montmorillonite and ni speciation significantly changes with depth in the sediment indeed ni rich talc 25 56 and ni goethite 15 23 disappear below 15 cm depth in the sediment and are replaced by ni sorbed pyrite 23 52 in redox active intermediate depth layers and by pyrite 34 55 in the deepest sediment layers ni incorporation in pyrite is especially observed beneath an inland avicennia stand where anoxic conditions are dominant in contrast beneath a rhizophora stand closer to the ocean where the redox cycle is intensified due to the tide cycle partial re oxidation of ni bearing pyrites favors nickel mobility as confirmed by ni mass balance estimates and by higher ni concentration in the pore waters these findings have important environmental implications for better evaluating the protective role of mangroves against trace metal dispersion into marine ecosystems they may also help in predicting the response of mangrove ecosystems to increasing anthropogenic pressure on coastal areas

slab1 0 a three dimensional model of global subduction zone geometries 1 we describe and present a new model of global subduction zone geometries called slab1 0 an extension of previous efforts to constrain the two dimensional non planar geometry of subduction zones around the focus of large earthquakes slab1 0 describes the detailed non planar three dimensional geometry of approximately 85 of subduction zones worldwide while the model focuses on the detailed form of each slab from their trenches through the seismogenic zone where it combines data sets from active source and passive seismology it also continues to the limits of their seismic extent in the upper mid mantle providing a uniform approach to the definition of the entire seismically active slab geometry examples are shown for two well constrained global locations models for many other regions are available and can be freely downloaded in several formats from our new slab1 0 website http on doi gov d9arbs we describe improvements in our two dimensional geometry constraint inversion including the use of average active source seismic data profiles in the shallow trench regions where data are otherwise lacking derived from the interpolation between other active source seismic data along strike in the same subduction zone we include several analyses of the uncertainty and robustness of our three dimensional interpolation methods in addition we use the filtered subduction related earthquake data sets compiled to build slab1 0 in a reassessment of previous analyses of the deep limit of the thrust interface seismogenic zone for all subduction zones included in our global model thus far concluding that the width of these seismogenic zones is on average 30 larger than previous studies have suggested

concentration distribution and assessment of heavy metals in sediments of mud area from inner continental shelf of the east china sea heavy metals cr cu zn cd pb hg and as grain size ph eh and total organic material tom and tn of 59 surficial sediments of mud area from the inner continental shelf of the east china sea have been analyzed the relations of the heavy metals to sediment composition ph reduction oxidation conditions and total organic materials were evaluated with multivariate statistics analysis and the hydrodynamic conditions such as coastal current and taiwan warm current are the other important controlling factors to the distribution of heavy metals sediment enrichment factors and potential ecological hazard index e text ri were used to assess the heavy metals accumulation the results indicate that moderate contamination of most heavy metals is prevalent and the contamination level in the estuary is rather high which is mainly from anthropogenic source compared with other areas in china the contaminant level of the study area is moderate

rapid estimation of first order rupture characteristics for large earthquakes using surface waves 2004 sumatra andaman earthquake 1 broadband surface waves from large earthquakes can be rapidly processed to estimate seismic moment faulting duration and general slip distribution supplying important information for hazard response efforts including tsunami warnings deconvolution of surface wave green s functions removes propagation effects yielding azimuthally varying effective source time functions even a single faultperpendicular time function can provide robust first order estimates of the temporal history of seismic radiation and associated slip distribution simplified two dimensional finite fault modeling using a few surface wave time functions can reliably characterize the smooth component of the overall rupture process these procedures are demonstrated using 13 rayleigh wave observations for the 26 december 2004 sumatra andaman earthquake yielding satisfactory agreement with models based on more complete seismic data sets depending on source and station locations stable slip estimates can be obtained within 15 60 minutes of the onset of a large earthquake citation ammon c j a a velasco and t lay 2006 rapid estimation of first order rupture characteristics for large earthquakes using surface waves 2004 sumatra andaman earthquake geophys res lett 33 l14314 doi 10 1029 2006gl026303

a review of the ecological and taphonomic controls on foraminiferal assemblage development in intertidal environments intertidal foraminifera from surface sediments are commonly used as a high resolution indicator of sea level change the integrity of this approach is based upon the assumption that surface assemblages are similar in composition to their buried fossil counterparts this assumption may in some cases be inappropriate due to subsurface or infaunal production and taphonomic alteration here we review the current understanding of foraminiferal production and taphonomic loss in intertidal environments and examine the extent to which these processes can affect the development of foraminiferal assemblages in intertidal environments as a sediment layer undergoes burial dead tests are added at a rate proportionate to the standing crop at that depth as a consequence test accumulation within the layer is proportionate to the depth integrated standing crop depending on the nature of its vertical living distribution the upper 1 cm of sediment may therefore not adequately characterise a given species total input instead a comparison of each species contribution to the entire depth integrated living community may offer a better a priori estimate of relative input to the sediment column this provides an improved base line for identifying true taphonomic trends downcore the potential for infauna to create discrepancies between surface and subsurface assemblages may be minimised however where 1 reproduction is concentrated near to the sediment surface transforming an apparent infaunal standing crop into an effective epifaunal production 2 the living fauna is composed similarly at all depths of production and or 3 intense bioturbation homogenises the upper sediment layers the likely decline in the intensity of taphonomic processes with depth may mean that the foraminiferal production from different depths may not experience taphonomic processes uniformly consequently in addition to their possible gradual enrichment due to subsurface production infaunal species may be preferentially preserved by virtue of their production closer to the base of the taphonomically active zone additionally homogenisation of the sediment column by reworking may mix temporally and perhaps environmentally distinct faunas affecting the stratigraphic integrity of the sediment deposit the most important taphonomic processes in intertidal environments are those associated with early diagenesis while the organic cements of agglutinated taxa may be directly oxidised the associated changes in the saturation state of porewaters with respect to calcium carbonate may affect calcareous species the type of diagenetic reaction operating within the sediment provides a quantitative control on agglutinated test degradation but a largely qualitative control on calcareous preservation in addition calcareous test preservation is dependent upon the rate with which organic matter is supplied while agglutinated test preservation is independent of organic matter concentrations although the specific morphological pathways of test degradation for calcareous species are well understood the stages under which agglutinated tests are lost are less clear the combined but varying influences of production infaunal and species composition taphonomic processes and bioturbation may create complex pathways in the transition from live to dead to fossil assemblages understanding the extent to which infauna taphonomic loss and sediment reworking affect assemblage development in different intertidal environments is essential in order to interpret the fossil record

wetland dynamics of marajo island northern brazil during the last 1000 years abstract the wetland dynamics in eastern amazon region during the last thousand years were studied by pollen analysis and ams radiocarbon date three sediment cores were sampled from the marajo island which is located at the mouth of the amazon river marajo island is covered mainly by amazon coastal forest herbaceous and varzea vegetation one core was obtained from lake arari which is surrounded by herbaceous vegetation flooded by freshwater two cores were sampled from an herbaceous plain that lies 45 km southeast from the lake arari the pollen records indicate that the herbaceous vegetation began its development approximately 800 cal yr b p the pollen percentages between 750 and 500 cal yr b p indicate the expansion of mangroves the predominance of herbaceous and varzea pollen occurs between 500 and 200 cal yr b p and the varzea pollen percentage increased during the last 200 years the vegetation changes proposed by the pollen records from the lake arari probably represent the regional vegetation dynamics of the marajo island while the pollen profiles from herbaceous plain present a smaller spatial representativeness of the vegetation the alternation between fresh and brackish water vegetation in the wetlands may indicate changes in the physicochemical characteristics of the sediment during the time interval studied

slip distribution of the february 27 2010 mw 8 8 maule earthquake central chile from static and high rate gps insar and broadband teleseismic data 1 the shallow depth underthrust earthquake of february 27 2010 mw 8 8 ruptured the subduction plate interface in central chile between 34 s and 38 s we retrieve the spatial and temporal distribution of slip during this mega earthquake through a joint inversion of teleseismic records insar and high rate gps hrgps data additionally our model is shown to agree with broadband surface waves rupture initiated at about 32 km depth and propagated bilaterally resulting in two main slip zones located ssw and nne of the hypocenter nucleation did not take place within or at the edge of one of these main asperities but in between during the first 30s slip propagated predominantly southwards later on the rupture evolved more slowly and more symmetrically eventually the northern asperity became predominant with maximum slip reaching about 20 m most of the seismic moment was released within 110s a relatively short time explained by the bilateral propagation the overall average rupture velocity is 2 6 km s but propagation occurred initially faster towards the south 3 2 km s large slip did not reach the trench a result consistent with the moderate size of the tsunami down dip rupture stopped at about 50 km depth in agreement with the lower limit of the locked zone inferred by ruegg et al 2009 from pre seismic gps data

are mangrove forest substrates sediments or soils a case study in southeastern brazil abstract morphological and analytical data corresponding to several profiles from two mangrove systems in the brazilian state of sao paulo were examined for evidence of pedogenetic processes plant activity exerted a strong effect on the processes occurring in mangrove substrates especially on the intensity of these processes and therefore constitutes one of the major factors involved in the differentiation of sediments and soils colonization of substrates by vascular plants leads to drastic changes in physicochemical conditions the redox processes were much more diverse in the soil than in the sediment substrate without vegetation in the former they varied with depth with oxic or suboxic conditions being observed at the surface and anoxic conditions observed below 30 cm whereas in the sediment anoxic conditions were observed throughout likewise the acid base conditions were more variable in the soils ranging from strongly acid to neutral and in the sediment they were close to neutral furthermore different pedogenetic processes were identified 1 addition of organic matter by accumulation of vegetable debris and dead roots with formation in some cases of a histic epipedon 2 transfer of soluble iron fe2 towards the surface and precipitation in the form of fe oxyhydroxide and transfer of the mineral particles due to the bioturbation caused by activity of crabs 3 transformation of elements such as iron gleization and sulphur sulphidization changes undergone in the mangrove substrates were also characterized by simultaneity and intergradations between pedogenesis and diagenesis especially in the lowermost layers in which authigenesis appears to intensify thus the presence of smectite minerals in the clay fraction may be attributed to authigenic processes that take place in both soils and sediments

sulfide diagenesis and sedimentation in the albian harmon member western canada abstract the albian harmon member comprises three lithofacies lm laminated mudstone resulted from hemipelagic sedimentation under dominantly anoxic conditions lbs laminated to bioturbated siltstone was deposited primarily by distal storm or turbidity currents under dysaerobic to anoxic conditions icm interbedded conglomerate mudstone represents deposition of turbidites or tempestites in more proximal basin margin facies under dysaerobic to perhaps aerobic conditions the rapid and episodic deposition of lbs and icm compared to the slower steadier rate of deposition for lm lithofacies is interpreted to be a primary control on the carbon sulfur and iron systematics of the sediments and the morphology and isotopic composition of authigenic pyrite pyrite in lm lithofacies is homogeneously distributed and occurs almost exclusively as discrete framboids less than 20 m in size lm lithofacies is further characterized by relatively constant carbon sulfur ratios iron sulfur ratios and 34s values for pyrite that indicate virtual open system conditions with respect to sulfate evaluation of organic matter om maturity and hydrogen indices hi suggests that om reactivity limite sulfate reduction in these sediments pyrite in lbs and icm lithofacies transition zone generally is distributed heterogeneously and occurs as framboidal zoned or massive aggregates up to 400 m in size transition zone sediments have extremely variable carbon sulfur and iron sulfur ratios and pyrite 34s values pyrite in these sediments is enriched in 34s relative to lm sediments indicating that the exchange of sulfate between pore waters and the overlying water column was restricted with sulfate reduction sometimes occurring under virtual closed system conditions with respect to sulfate

pore water chemistry in mangrove sediments relationship with species composition and developmental stages french guiana spatial and seasonal variability of sedimentary salinity ph redox potential and solid phase sulphide concentration were investigated in a range of mangrove communities along the coast of french guiana seasonal depth distributions of these parameters and organic content were compared within avicennia rhizophora and mixed mangrove stands at different stages of plant development mangrove communities and variable surface water inputs strongly impact sediment and ground water properties in the upper sediment changes in salinity are mainly controlled by seasonal conditions transpiration and proximity of fresh water influx whereas we suggest that constant basal salinity results from an accumulation of salt that has migrated as a result of density driven convection processes there are no clear differences between the depth distributions of salinity obtained beneath avicennia germinans and rhizophora mangle stands implying that plant zonations are not primarily controlled by soil salinity in this environment nevertheless r mangle grows in places subjected to the greatest variability in freshwater influxes suggesting that rhizophora might require or withstand occasional inundation by fresh water beneath rhizophora stands sediment properties reflect anaerobic and sulphidic conditions close to the sediment surface in contrast beneath avicennia stands sediment geochemistry mostly depends on the stages in forest development on contents in sedimentary organic matter and on seasonal changes in the early stage of avicennia settlement the sediment at the level of radial pneumatophore bearing cable roots displays permanent suboxic conditions with eh values reaching 400 mv these high ehs are interpreted as an effect of the oxidation produced by the cable root system the development of mature avicennia stands results in accumulation of sedimentary organic matter and promotes low ehs and the reduction of pore water sulphate near cable root level the oxidation process observed in pioneer mangroves results in a reoxidation of solid sulphides produced previously during dry conditions the desiccation of the upper sediment adds its oxidation effects to those of root activity as a result suboxic processes dominate in the upper 20 cm thick layer organic matter decomposition and sulphur oxidation strongly acidify the sediment below 20 cm the sediment is anaerobic and sulphidic hence sulphide concentrations depend on the edaphic conditions controlling decay processes and appear to be a consequence rather than a cause of the observed zonation of vegetal species the small size of a germinans propagules might have a significant influence on the extensive development of this plant community along the highly dynamic coastline of the guianas this study demonstrates that the different properties of pore water were intimately linked and that the explanation of the evolution of this forest reflects a combination of multiple parameters moreover it appeared that the organic content played a key role along with the species composition and the seasonal variations waterlogging desiccation

evidence of large scale repeating slip during the 2011 tohoku oki earthquake 1 the repetition of slip during rupture process of earthquake is a debate issue which had never been confirmed clearly in the past big events due to the lack of dense near field observations and limited resolution in time of source model the 2011 m9 0 tohoku oki earthquake generated a wealth seismic records which provided us an unprecedented opportunity to study the rupture evolution of giant earthquake at a high spatio temporal resolution here we use teleseismic local strong motion and near field coseismic geodetic data to investigate the source rupture process of this event based on the parallel inversion technique the results reveal a broad slip zone with remarkable large scale repeating slip during the earthquake the inverted source model shows several time periods of energy release with three main peaks these energy bursts and temporal rupture snapshots suggest repetition of a large scale slip on the biggest asperity this rupture behavior resulted in 50 m slips on the slip zone and prolonged the entire rupture process for a long duration of 160 seconds the proposed source model is in a good agreement with the aftershock distribution and can interpret the characteristics of local strong motions further investigations of repeating slip during this event are crucial which will deeply transform earthquake science from dynamic point of view

foraminiferal biofacies across mangrove mudflat environments at cocoa creek north queensland australia contemporary and relict subsurface intertidal foraminiferal dead assemblages were collected from a site near to cocoa creek north queensland australia and analysed for the purpose of understanding fossil assemblage development and preservation a marked dichotomy was identified between dead foraminiferal assemblages within mangrove sediments and those within adjacent mudflat sediments mangrove assemblages were almost exclusively represented by agglutinated species mainly arenoparrella mexicana haplophragmoides wilberti milliammina fusca m obliqua trochammina inflata while calcareous species dominated the mudflat mainly ammonia aoteana pararotalia venusta parrellina hispidula surface and subsurface test abundances were also an order of magnitude greater within mudflat sediments 1000 3000 tests per cm3 than in the sediments beneath the mangroves 100 300 tests per cm3 statistically significant differences in the abundance of calcareous and agglutinated tests between wet and dry seasons within the mangrove suggest that tests are systematically lost from this part of the system on an annual basis a model of assemblage formation under shoreface progradation is presented which makes a direct link between surface assemblages post depositional processes and the composition and environmental resolution of the fossil assemblages entering the stratigraphic record assemblages within the mangrove undergo rapid taphonomic loss and are then overprinted during burial by the deep infaunal communities associated with the prograding higher elevation environments as such much of the eventual mangrove sequence is represented entirely by assemblages produced relatively recently within an upper mangrove environment and therefore cannot be differentiated according to elevation at the time of deposition in addition organic enrichment of upper mudflat deposits by mangrove roots which occurs during progradation results in the dissolution of calcareous tests from an 40 cm thick stratigraphic interval it is argued that in order to reliably recognise the changes to foraminiferal assemblages which occur during burial assemblages must be compared with respect to stratigraphy rather than reflexively downcore

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

geochemical investigation of the south wellesley island wetlands insight into wetland development during the holocene in tropical northern australia the south wellesley islands in the gulf of carpentaria northern australia were the recent focus of a palynological investigation which found vegetation change during the holocene was driven by coastal progradation and regional climate here we present new elemental data from x ray fluorescence core scanning which provides non destructive continuous and high resolution analysis from three wetlands across bentinck island the largest of the south wellesley islands elemental data and grain size analyses are combined with lead 210 210pb and accelerator mass spectrometry ams carbon 14 14c dates an open coastal environment was present 1250 cal a bp on the south east coast of bentinck island with sediment supply incorporating fluvial deposition and detrital input of titanium and iron from eroding lateritic bedrock prograding shorelines dune development and river diversion formed a series of swales parallel to the coast by 800 cal a bp forming the marralda wetlands wetlands developed at sites

mangrove expansion in the gulf of mexico with climate change implications for wetland health and resistance to rising sea levels abstract black mangroves avicennia spp are hypothesized to expand their latitudinal range with global climate change in the 21st century induced by a reduction in the frequency and severity of coastal freezes which are known to limit mangrove colony extent and individual tree size the gulf of mexico is a prime candidate for population expansion to occur because it is located at the northward limit of black mangrove habitat this may come at the expense of existing coastal saline wetlands that are dominantly spartina spp marsh grasses the present study was conducted to focus on the implications of a marsh to mangrove transition in gulf wetlands specifically 1 wetland resistance to accelerating eustatic sea level rise eslr rates 2 resistance to wave attack in large storms increased cyclonic storm frequency intensity is predicted with future climate warming and 3 organic carbon sequestration and wetland soil geochemistry field sites of adjacent and inter grown avicennia germinans mangrove and spartina marsh populations in similar geomorphological setting were selected in back barrier areas near port aransas and galveston tx elevation surveys in the more mature port aransas site indicate mangrove vegetated areas are 4 cm higher in elevation than surrounding marsh on an average regional scale and 1 2 cm higher at the individual mangrove scale 210pb and 137cs accumulation rates and loss on ignition data indicate that mineral trapping is 4 1 times higher and sediment organics are 1 7 times lower in mangroves at port aransas this additional mineral trapping does not differ in grain size character from marsh accumulation elevation change may also be effected by soil displacement of higher root volumes in mangrove cores port aransas porosities are lower in mangrove rooted horizons with a corresponding increase in sediment strength suggesting mangrove intervals are more resistant to wave induced erosion during storm events port aransas mangroves exhibit higher pore water redox potentials and salinities over entire core depths and depressed ph over rooted intervals suggesting a distinct diagenetic environment exists relative to marsh sites the rooting network which introduces oxygen into the sediment and focuses evapo transpiration and salt exclusion within this zone may prove advantageous when competing with grasses by elevating salinities to levels that are toxic for spartina trends observed in the more mature systems of port aransas are generally absent in galveston suggesting the youth and physically shorter stature of these systems means they have not yet established a unique sediment signature

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

concentration distribution and assessment of heavy metals in the surface sediments of the western gulf of thailand heavy metals cr cu zn cd pb hg as grain size ph eh total organic carbon and total nitrogen of 157 surface sediments from the western gulf of thailand got were analyzed to determine the spatial distribution pattern constraint factors and pollution status of heavy metals in the surface sediments of the western got the relationships of the heavy metals with sediment composition ph reduction oxidation conditions and total organic materials were evaluated by statistical analysis sediment compositions were the main factors controlling the concentrations of heavy metals as reported in many previous studies while the hydrodynamic conditions in particular the seasonal eddies were an important factor controlling their distribution both sediment enrichment factor and geoaccumulation index were used to assess heavy metal accumulation only as reached the light contamination level near the upper got and the coastal area close to the songkhla province due primarily to anthropogenic activities

source description of the 1999 hector mine california earthquake part ii complexity of slip history we present a rupture model of the hector mine earthquake m 7 1 determined from the joint inversion of strong motion records p and sh teleseismic body waves global positioning system gps displacement vectors and measured surface offset we solve for variable local slip rake angle rise time and rupture velocity of a finite fault model involving multiple segments the inversion methodology developed in a companion article ji et al 2002 combines a wavelet transform approach with a nonlinear simulated annealing algorithm the final model is checked by forward simulating the interferometric synthetic aperture radar insar data our estimation to the seismic moment is 6 28 10 19 n m which is distributed along three segments from north to south releasing 37 41 and 22 of the total moment respectively the average slip is 1 5 m with peak amplitudes as high as 7 m the fault rupture has an average rise time of 3 5 sec and a relatively slow average rupture velocity 1 9 km sec resulting in a 14 sec rupture propagation history our approach permits large variation in rupture velocity and rise time and indicates that rise time appears to be roughly proportional to slip and shorter rise times are associated with the initiation of asperity rupture we also find evidence for nearly simultaneous rupture of the two northern branches