high resolution image treatment in ichnological core analysis initial steps advances and prospects abstract ichnological studies have become popular during the last decades particularly those associated with the development of two major concepts the ichnofacies model and ichnofabric approach they have driven ichnology into diverse fields of earth sciences including paleoecology sedimentology paleoceanography and basin analysis as well as applied fields for the oil and gas industry and aquifer characterization whereas early ichnological analyses focused on outcrops later the number of ichnological studies on well cores increased noticeably still ichnological research on cores is hampered by certain limitations i e mainly narrow exposed surface and the characterization of ichnological properties is complicated when cores are involved to facilitate ichnological analysis in cores from modern deposits several techniques among them x rays magnetic resonance and computed tomography have been used with the development of computer software a new high resolution image treatment has emerged as a powerful tool in different branches of ichnological studies especially for cores from modern marine deposits because applications are numerous and perhaps not familiar to all the scientific community this paper provides an overview of the usefulness of image treatment in ichnological analysis its first steps and subsequent development the novel techniques most recently used in the study of cores from modern marine deposits and some challenges for future research

end cretaceous marine mass extinction not caused by productivity collapse an asteroid impact at the end of the cretaceous caused mass extinction but extinction mechanisms are not well understood the collapse of sea surface to sea floor carbon isotope gradients has been interpreted as reflecting a global collapse of primary productivity strangelove ocean or export productivity living ocean which caused mass extinction higher in the marine food chain phytoplankton dependent benthic foraminifera on the deep sea floor however did not suffer significant extinction suggesting that export productivity persisted at a level sufficient to support their populations we compare benthic foraminiferal records with benthic and bulk stable carbon isotope records from the pacific southeast atlantic and southern oceans we conclude that end cretaceous decrease in export productivity was moderate regional and insufficient to explain marine mass extinction a transient episode of surface ocean acidification may have been the main cause of extinction of calcifying plankton and ammonites and recovery of productivity may have been as fast in the oceans as on land

developing an event tree probabilistic tsunami inundation model for ne atlantic coasts application to a case study this study constitutes a preliminary assessment of probabilistic tsunami inundation in the ne atlantic region we developed an event tree approach to calculate the likelihood of tsunami flood occurrence and exceedance of a specific near shore wave height for a given exposure time only tsunamis of tectonic origin are considered here taking into account local regional and far field sources the approach used here consists of an event tree method that gathers probability models for seismic sources tsunami numerical modeling and statistical methods it also includes a treatment of aleatoric uncertainties related to source location and tidal stage epistemic uncertainties are not addressed in this study the methodology is applied to the coastal test site of sines located in the ne atlantic coast of portugal we derive probabilistic high resolution maximum wave amplitudes and flood distributions for the study test site considering 100 and 500 year exposure times we find that the probability that maximum wave amplitude exceeds 1 m somewhere along the sines coasts reaches about 60 for an exposure time of 100 years and is up to 97 for an exposure time of 500 years the probability of inundation occurrence flow depth 0 m varies between 10 and 57 and from 20 up to 95 for 100 and 500 year exposure times respectively no validation has been performed here with historical tsunamis this paper illustrates a methodology through a case study which is not an operational assessment

source characteristics of the nicaraguan tsunami earthquake of september 2 1992 a large ms 7 2 shallow earthquake took place off the pacific coast of nicaragua on september 2 1992 and set off large tsunamis the ground motion of the main shock was very weak along the whole nicaraguan coast a tsunami as high as 10 m was observed at el transito whereas a height of about 2 m is empirically expected for an earthquake of ms 7 2 the tsunami magnitude mt is estimated to be 7 9 from tide gage data the nicaraguan event is a tsunami earthquake which generates unusually large tsunamis for its earthquake magnitude the source mechanism is studied in detail by using waveforms of body waves and surface waves recorded on global broadband seismographs the possibility of single force source is ruled out from radiation patterns and the amplitude ratio of rayleigh and love waves the main shock is interpreted as a low angle thrust fault with strike 302 dip 16 and slip 87 the cocos plate underthrusting beneath the caribbean plate the seismic moment from surface wave analysis is 3 0 1020 nm mw 7 6 the source dimension is estimated to be 200 km 100 km from the aftershock area the inversion results of body waves suggest bilateral rupture with rupture velocity as low as 1 5 km s and duration time of about 100 s the source process time is unusually long indicating that the associated crustal deformation has a long time constant

parameters of tsunami source versus earthquake magnitude this study employs an empirical analytical approach in combination with monte carlo method to establish relationships between earthquake moment magnitude and upper limits of tsunami source parameters double amplitude of vertical bottom deformation displaced water volume and potential energy of initial elevation the approach is based on the okada solution for a finite rectangular fault and empirical scaling laws for earthquake sources results are compared to empirical and theoretical relationships published previously parameters of some recent tsunami sources those for which usgs provides slip distribution data are considered in light of the established relationships

tsunami modeling to validate slip models of the 2007 mw8 0 pisco earthquake central peru following the 2007 august 15th mw 8 0 pisco earthquake in central peru sladenet al j geophys res 115 b02405 2010 have derived several slip models of this event they inverted teleseismic data together with geodetic insar measurements to look for the co seismic slip distribution on the fault plane considering those data sets separately or jointly but how close to the real slip distribution are those inverted slip models to answer this crucial question the authors generated some tsunami records based on their slip models and compared them to dart buoys tsunami records and available runup data such an approach requires a robust and accurate tsunami model non linear dispersive accurate bathymetry and topography etc otherwise the differences between the data and the model may be attributed to the slip models themselves though they arise from an incomplete tsunami simulation the accuracy of a numerical tsunami simulation strongly depends among others on two important constraints i a fine computational grid and thus the bathymetry and topography data sets used which is not always available unfortunately and ii a realistic tsunami propagation model including dispersion here we extend sladen s work using newly available data namely a tide gauge record at callao lima harbor and the chilean dart buoy record while considering a complete set of runup data along with a more realistic tsunami numerical that accounts for dispersion and also considering a fine resolution computational grid which is essential through these accurate numerical simulations we infer that the insar based model is in better agreement with the tsunami data studying the case of the pisco earthquake indicating that geodetic data seems essential to recover the final co seismic slip distribution on the rupture plane slip models based on teleseismic data are unable to describe the observed tsunami suggesting that a significant amount of co seismic slip may have been aseismic finally we compute the runup distribution along the central part of the peruvian coast to better understand the wave amplification attenuation processes of the tsunami generated by the pisco earthquake

the chicxulub asteroid impact and mass extinction at the cretaceous paleogene boundary the cretaceous paleogene boundary similar to 65 5 million years ago marks one of the three largest mass extinctions in the past 500 million years the extinction event coincided with a large asteroid impact at chicxulub mexico and occurred within the time of deccan flood basalt volcanism in india here we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction notably a single ejecta rich deposit compositionally linked to the chicxulub impact is globally distributed at the cretaceous paleogene boundary the temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations for example darkness and cooling lead us to conclude that the chicxulub impact triggered the mass extinction

an iridium rich layer at the cretaceous tertiary boundary in the bidart section southern france we have measured an anomalous iridium concentration in the clays of the cretaceous tertiary boundary in the bidart section thus confirming the planetary character of this anomaly the iridium anomaly is synchronous with a very sharp minimum of the 13c 12c ratio and there is no evidence of any other iridium enrichment in marly concentrations away from the boundary the integrated iridium content is of the same order of magnitude as that calculated from deep sea cores in the pacific ocean in spite of a careful search we have found no evidence of any exotic material

microscale trace element distribution across the cretaceous palaeogene ejecta layer at the agost section constraining the recovery of pre impact conditions abstract a high resolution sub mm scale analysis of the distribution of major and trace elements across the ejecta layer marking the cretaceous palaeogene boundary kpgb at the agost section se spain was performed using laser ablation inductivity coupled plasma mass spectrometry la icp ms a kpgb interval 17 mm thick has been selected for this study it includes gray calcareous marl from the uppermost maastrichtian cretaceous 2 02 mm thick red clay the ejecta layer and blackish gray clay boundary clay layer from the lowermost danian palaeogene the unconsolidated sediments were resin embedded under o2 free conditions and analyzed by la icp ms line continuous scan measurements at 20 m increments and a laser beam of 120 m these micron scale analyses show that the anomalous contents of trace and major elements in this boundary are restricted to the ejecta layer which displays a relatively uniform distribution over its 2 mm thickness trace and major elemental ratios such as ca al ti al cr al fe al ni al cu al zn al as al sb al and pb al have similar values below and above the ejecta layer consistent with similar palaeoenvironmental conditions prior to and after the impact event such element distribution points to anomalies exclusively restricted to the ejecta thus a nearly instantaneous re establishment of pre impact conditions right after the impact event is observed

tsunami earthquakes vertical pop up expulsion at the forefront of subduction megathrust abstract published slip distribution models based on geodetic seismological and tsunami data of the m w 7 8 2010 mentawai tsunami earthquake offshore south central sumatra suggest that the large tsunami wave was generated by a narrow swath of high seafloor uplift along the accretionary wedge front implying higher vertical throw than that consistent with slip on the shallow dipping megathrust here we present high resolution seismic reflection profiles across the 2010 rupture zone that image the youngest deformation at the accretionary wedge front the profiles reveal conjugate steeply dipping active thrust faults that branch upwards from the megathrust and bound triangular pop ups the seismologically determined co seismic slip 10 m on the 6 dipping decollement probably caused a comparable amount of upward expulsion of these 3 km wide flat topped pop ups co seismic throw on the 60 dipping thrusts that bound the pop up plateaus maximize the uplift of the seafloor and overlying water column providing an additional localised tsunami source tsunami simulations show that such combined deformation i e the broad scale seafloor displacement caused by slip on the megathrust and the localized 8 10 m seafloor uplift across a 6 9 km wide pop up belt involving up to three pop ups is able to reproduce the 2010 tsunami amplitude measured by a dart buoy and observed run up heights in the mentawai islands this simple mechanism observed in analogue sandbox shortening experiments may thus efficiently generate the oversize waves that characterize tsunami earthquakes systematic mapping of pop ups along accretionary wedge fronts may help identify trench segments prone to produce the special class of seismic events that spawn exceptionally large tsunamis

sediment effect on tsunami generation of the 1896 sanriku tsunami earthquake the 1896 sanriku earthquake was one of the most devastating tsunami earthquakes which generated an anomalously larger tsunami than expected from its seismic waves previous studies indicate that the earthquake occurred beneath the accretionary wedge near the trench axis it was pointed out recently that sediments near a toe of an inner trench slope with a large horizontal movement due to the earthquake might have caused an additional uplift in this paper the effect of the additional uplift to tsunami generation of the 1896 sanriku tsunami earthquake is quantified we estimate the slip of the earthquake by numerically computing tsunamis and comparing their waveforms with those recorded at three tide gauges the estimated slip for the model without the additional uplift is 10 4 m and those with the additional uplift are 5 9 6 7 m this indicates that the additional uplift of the sediments near the trench has a large effect on the tsunami generation

cretaceous paleogene boundary bathyal paleo environments in the central north pacific dsdp site 465 the northwestern atlantic odp site 1049 the gulf of mexico and the tethys the benthic foraminiferal record uppermost maastrichtian benthic foraminiferal assemblages n63 am are diverse indicating mesotrophic conditions in lower bathyal dsdp hole 465a hess rise central north pacific in 4 lower bathyal land sections in central east and northeastern mexico and in the upper to middle bathyal agost section tethys area southeastern spain they indicate more eutrophic conditions in lower bathyal odp hole 1049c blake nose northwestern atlantic benthic foraminifers did not suffer significant extinction at the k pg boundary but diversity and heterogeneity of the assemblages and the percentage of infaunal morphogroups decreased drastically in all sections with the exception of dsdp hole 465a where the percentage of infaunal taxa increased these faunal changes probably reflect the effect on the benthic faunas of a widespread decrease in the food supply to the sea floor as a result of the collapse of primary productivity at the k pg boundary the decrease in food supply apparently affected the benthic faunas least at more eutrophic nwatlantic odp site 1049 and at pacific dsdp site 465 which is distal from the impact site of the k pg bolide on the yucatan peninsula at these sites the faunas recovered within the parvulorugoglobigerina eugubina biozone 100 ky although diversity and heterogeneity remained low through the early danian possibly indicating environmental stress this stress might be related to a high or fluctuating food supply by primary producers that could not easily be used by the benthos such as various bloom species of dinoflagellates benthic assemblages recovered more slowly 300 ky in the mexican and spanish sections low oxygen conditions after the k pg boundary could be inferred from the benthic assemblages at agost southeastern spain only a short episode of hypoxia however may be obscured at pacific dsdp hole 465a by drilling disturbance and in the mexican sections and hole 1049c by incomplete sections due to downslope transport benthic foraminiferal assemblages thus appear to have been affected by the collapse of

benthic foraminiferal turnover across the cretaceous paleogene boundary at agost southeastern spain paleoenvironmental inferences abstract we studied upper cretaceous and lower paleogene benthic foraminifera from the agost section southeastern spain to infer paleobathymetrical changes and paleoenvironmental turnover across the cretaceous paleogene k p transition benthic foraminifera indicate uppermost bathyal depths at agost during the abathomphalus mayaroensis biochron from about 400 kyr before the k p boundary through the early plummerita hantkeninoides biochron about 120 150 kyr before that boundary the depth increased to middle bathyal for the remainder of the cretaceous and remained so for the danian part of the studied section parasubbotina pseudobulloides biochron at least 200 kyr after the k p boundary there were no perceivable bathymetrical changes at the k p boundary where 5 of the species became extinct and the species composition of the benthic foraminiferal fauna changed considerably below the boundary infaunal morphogroups constitute up to 65 73 of the faunas directly above the boundary in the black clays of the lower guembelitria cretacea biozone benthic foraminifera are rare several opportunistic taxa e g the agglutinant haplophragmoides sp have short peaks in relative abundance possibly reflecting low oxygen conditions as well as environmental instability with benthos receiving food from short lived local blooms of primary producers above the clays through the end of the studied interval epifaunal morphogroups dominate up to 70 of the assemblages or there is an even mixture or epifaunal and infaunal morphogroups infaunal groups do not recover to pre extinction relative abundances indicating that the food supply to the benthos did not recover fully over the studied interval about 200 kyr after the k p boundary the benthic foraminiferal faunal changes are compatible with the direct and indirect effects of an asteroid impact which severely destabilized primary producers and the oceanic food web that was dependent upon them

ichnological analysis of the bidart and sopelana cretaceous paleogene k pg boundary sections basque basin w pyrenees refining eco sedimentary environment abstract ichnological analysis of two cretaceous paleogene boundary sections at bidart se france and sopelana n spain has been conducted in order to refining eco sedimentary environment and to a make comparison with previous interpretations based on microfossils in both sections trace fossil assemblage is low diverse consisting of chondrites planolites thalassinoides trichichnus zoophycos and phycosiphon ascribed to the zoophycos ichnofacies however with distinct differences in the bidart section early danian dark filled trace fossil assemblage is more abundant in large thalassinoides zoophycos and larger chondrites and less abundant in trichichnus and small chondrites in comparison to the sopelana section sopelana is thus interpreted as a more offshore deeper section than bidart although both were located in the upper bathyal zone of the basin oxygenation below the sediment water interface was enough to favour a generalized total bioturbation of sediments the presence of chemichnia and trace fossils which tracemakers sequestered sediments from the sea floor in deep burrows zoophycos suggests at least periodical food deficiency the distribution and content of trace fossils across the k pg boundary do not change significantly revealing minor incidence of the k pg boundary event on the macrobenthic environment the k pg boundary transition including the boundary layer is nearly totally bioturbated hence a redistribution of microbiotic and abiotic components by tracemakers is possible

two subevents across the japan trench during the 7 december 2012 off tohoku earthquake mw 7 3 inferred from offshore tsunami records a tsunamigenic earthquake with a moment magnitude of 7 3 occurred near the japan trench off tohoku northeast japan on 7 december 2012 operational seismic monitoring inferred that the earthquake was composed of doublet sources of comparable magnitudes the first event was reverse faulting and the second event which occurred 10 20 s later was normal faulting an associated tsunami was observed at offshore stations having an amplitude of 10 1 to 101 cm inverse modeling using the observed tsunami records reveals possible vertical seafloor deformations we can then constrain in terms of the source location that the tsunamigenic earthquake involves two subfaults across the japan trench one is the outer trench reverse faulting as the first event and the second is the inner trench normal faulting the present study shows that tsunami analysis with seismograph analyses effectively constrains the epicenter locations even in the case of complex earthquakes like doublets

toarcian oceanic anoxic event induced unusual behaviour and palaeobiological changes in thalassinoides tracemakers abstract the early toarcian early jurassic global marine mass extinction is associated with one of the most important environmental perturbations of the mesozoic the toarcian oceanic anoxic event t oae usually interpreted as a global oceanic anoxic event in the lusitanian basin lb one of the reference areas for the study of the t oae despite an elevated extinction rate among marine invertebrates the anoxia hypothesis has been discarded based on geochemical and isotopic data in the fonte coberta section the t oae is characterised by the extinction of the previously well represented brachiopod taxa a decreased abundance of ammonoids and the establishment of a well developed endobenthic community mainly composed by thalassinoides tracemaker which indicates favourable environmental parameters at least for this community thus the palaeoenvironmental changes associated with the t oae event bear a minor incidence on the macrobenthic tracemaker community at the level of extinctions and changes in diversity or abundance yet they exert a major effect on the behaviour and palaeobiology of tracemakers the thalassinoides specimens show an exclusively horizontal development and unusual architectural features during the extinction interval tied to behavioural adaptations to nutrient availability and or substrate firmness smaller burrow diameters are registered at the base of the t oae and then an increase is observed during the t oae this could be associated with a palaeobiological response lilliput effect to palaeoecological changes at the beginning of the t oae followed by a progressive change to pre event environmental parameters this study therefore sheds light on how environmental alterations can determine specific behavioural and palaeobiology changes of the producer as reflected by variations in significant features of thalassinoides architecture

dispersive tsunami of the 2010 chile earthquake recorded by the high sampling rate ocean bottom pressure gauges 1 cabled ocean bottom pressure gauges deployed offshore japan recorded the pressure change associated with the 2010 chile earthquake tsunami over a wider frequency range than that of coastal tide gauges or hydrophones although it was difficult to recognize the dispersive features in the original records the spectrograms clearly showed wave dispersion a low frequency tsunami 1 mhz arrived after an elapsed time of 24 hr from the earthquake origin time while a high frequency tsunami 9 mhz arrived after an elapsed time of 48 hr the arrival times can be explained by assuming a constant water depth of 4 km however the calculated waveform does not correctly reproduce the number of wave packets appearing in the observations cabled ocean bottom pressure gauges deployed offshore can record broadband tsunami signals reflecting the wide wavenumber range spatial spectrum for sea bottom deformation caused by the earthquake

fe oxide spherules infilling thalassinoides burrows at the cretaceous paleogene k p boundary evidence of a near contemporaneous macrobenthic colonization during the k p event a detailed ichnological analysis focused on thalassinoides structures recorded just below the cretaceous paleogene k p boundary layer of the agost section southeast spain aimed to evaluate macrobenthic colonization during the k p boundary event stereomicroscopy and field emission scanning electron microscopy analyses conducted on material filling in thalassinoides trace fossils reveal the presence of dark infill material that includes spherule like elements similar to those previously differentiated in the k p boundary layer energy dispersive x ray spectrometry indicates a ferruginous composition goethite spherules this represents the first record of spherules related to the k p boundary event within trace fossil infilling material the passive filling of this material into the thalassinoides bioturbation allows interpretation of the gravitational deposition just after thalassinoides trace maker colonization the absence of erosive sedimentary structures or other material deposited between the thalassinoides trace maker colonization and the spherule deposition is interpreted as evidence of rapid colonization during the k p boundary event nearly contemporary with the spherule layer deposition

carbon isotope evidence for the timing of the cretaceous palaeogene macrobenthic colonisation at the agost section southeast spain abstract the cretaceous palaeogene k t boundary section of agost southeast spain one of the most complete sections existing contains a well developed trace fossil assemblage composed of dark and light filled trace fossils registered in the uppermost cretaceous maastrichtian plummerita hantkeninoides biozone sediments the trace fossil assemblage reveals that significant macrobenthic colonisation occurred around the k t boundary interval however difficulties in recognising trace fossils affecting the k t boundary layer as well as in biostratigraphically characterising these trace fossils hindered a conclusive interpretation on the timing of this macrobenthic colonisation with the aim of this characterisation we determined the 13c of the carbonate fraction of dark and light filling materials from the trace fossils since the carbon isotope compositions of uppermost cretaceous and lowermost palaeogene materials are clearly different the data compiled provide evidence for a significant distinction between light filled trace fossils with 13c values higher than 1 6 peedee belemnite pdb and dark filled trace fossils with 13c values between 0 21 and 1 2 pdb most of these being lower than 0 7 pdb the comparison of these values with those from the uppermost maastrichtian to the lowermost danian sediments reveals that the macrobenthic colonisation occurred in different phases across the k t boundary interval

high resolution digital image treatment to color analysis on cores from iodp expedition 339 approaching lithologic features and bioturbational influence abstract color analysis was conducted on selected cores from sites u1385 and u1389 from iodp expedition 339 based on a recently developed high resolution digital image treatment to explore its relationship with lithologic features e g percentage of sand this first step can be of potential usefulness in characterizing discriminating between different types of registered sediments in the iodp expedition 339 turbidites contourites and associated sediments and then for more general studies involving different lithologies sedimentary parameters and ichnological variations differentiation between types of deposits holds particular interest in the context of the mediterranean outflow water mow evolution and related depositional processes whose study was one of the main aims of iodp expedition 339 color characterization was executed on high resolution digital images by applying a method based on adjustment modification including levels brightness and vibrance followed by pixel measurement the applied methodology allows for a precise characterization of colors improving upon previous color descriptions by means of munsell color conducted on board during expedition 339 itself the studied interval is subdivided into four parts based on grain size analysis and color according to pixel values these parts are identified as a 120 b 90 c 140 and d 160 being well correlated with the corresponding lithology parts a and c with similar pixel values correspond to calcareous silty mud mudstone part b would correlate with calcareous silty sand sandstones and part d corresponds to calcareous mud sand content distribution throughout the studied interval bears a close relationship with the differentiated parts a to d intervals having a higher percentage of sand present a lower mean pixel value and darker color whereas the finer grained intervals contain sediments lighter in color represented by higher pixel values however as proved the proposed relationship between color sedimentological features type of sediment must be considered with some caution ichnological analysis reveals the influence of trace fossils on color variations in the sediment regardless of the size of traces and amount of bioturbation the infilling material of trace fossils being the most determinant factor thus lower bioturbated surfaces 6 by small trace fossils chondrites show higher influence on color variations 102 vs 107 than higher bioturbated surfaces 25 by large trace fossils thalassinoides 110 vs 112 due to the color of the infilling material 56 in the case of chondrites and 90 in the case of thalassinoides thus a detailed ichnological analysis should accompany the sedimentological study of deep sea modern cores in order to avoid misinterpretations of the sedimentological parameters involved

tsunami sources of the november 2006 and january 2007 great kuril earthquakes abstract along the northern kuril trench a great interplate earthquake occurred in november 2006 followed by an outer rise normal fault event in january 2007 surface wave magnitudes m s 7 8 and 8 2 indicate that the 2007 event was larger while the global cmt solutions m w 8 3 and 8 1 indicate that the 2006 event was larger tsunamis from both events were recorded at tide gauge stations in japan russia and the united states as well as deep ocean assessment and reporting of tsunamis dart systems and cabled tsunami sensors installed on deep ocean bottom inversion of 52 tsunami waveforms indicates that the 2006 tsunami source was about 200 km long extending from the epicenter to northeast the largest slips of 4 7 m are estimated on the northeastern subfaults for the 2007 event inversion of 32 waveforms shows that the tsunami source was about 120 km long with the largest slip of 3 5 m on the northeastern subfault the agreements between the observed and synthetic tsunami waveforms are generally good for both events not only within the inversion time windows but also for the later phases which were not used in inversions the slip distributions yield the seismic moment of m w 8 1 for the 2006 event and m w 7 9 for the 2007 event the seismic moment of the 2006 event was larger than the 2007 event from comparison of tsunami data regardless of fault model

fault size and depth extent of the ecuador earthquake m w 7 8 of 16 april 2016 from teleseismic and tsunami data the april 2016 ecuador mw 7 8 earthquake was the first megathrust tsunamigenic earthquake along the ecuador colombia subduction zone since 1979 mw 8 2 with 200 deaths from tsunami while there was no tsunami damage from the 2016 earthquake small tsunamis were recorded at deep ocean assessment and reporting of tsunami and tide gauges here we designed various fault models with and without shallow slip area and compared the computed teleseismic and tsunami waveforms with the observations while teleseismic inversions were indifferent about inclusion or exclusion of the shallow slip tsunami waveforms strongly favored the slip model without shallow slip our final slip model has a depth range of 15 44 km and its western shallowest limit is located at the distance of 60 km from the trench maximum and average slips were 2 5 and 0 7 m respectively the large slip area was 80 km along strike 60 km along dip in the depth range of 15 35 km

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

fault parameters of the 1896 sanriku tsunami earthquake estimated from tsunami numerical modeling the june 15 1896 sanriku earthquake generated devastating tsunamis with the maximum run up of 25 m and caused the worst tsunami disaster in the history of japan despite its moderate surface wave magnitude ms 7 2 and weak seismic intensity this is a typical tsunami earthquake which generates anomalously larger tsunamis than expected from its seismic waves previously proposed mechanisms of tsunami earthquakes include submarine slumping and slow rupture in the accretionary wedge or in the subducted sediments in this paper we estimate the fault parameters of the 1896 tsunami earthquake by numerically computing the tsunami and comparing the waveforms with those recorded at three tide gauge stations in japan the result indicates that the tsunami source is very close to the japan trench and the fault strike is parallel to the trench axis the fault width is about 50 km suggesting that the tsunami earthquake is a slow rupture in the subducted sediments beneath the accretionary wedge

post impact event bed tsunamite at the cretaceous palaeogene boundary deposited on a distal carbonate platform interior we show crucial evidence for the cretaceous palaeogene k pg boundary event recorded within a rare succession deposited in an inner platform lagoon on top of a mesozoic tropical intra oceanic western tethys adriatic carbonate platform which is exposed at likva cove on the island of brac croatia the last terminal maastrichtian fossils appear within a distinct 10 12 cm thick event bed that is characterized by soft sediment bioturbation and rare shocked quartz grains and is interpreted as a distal tsunamite directly overlying this is a 2 cm thick reddish brown clayey mudstone containing planktonic foraminifera typical of the basal danian and with elevated platinum group elements in chondritic proportions indicating a clear link to the chicxulub asteroid impact these results strongly support the first discovery of a potential k pg boundary tsunamite on the neighboring island of hvar and these two complementary sections represent probably the most complete record of the event among known distal shallow marine successions

how bioturbation obscured the cretaceous palaeogene boundary record the cretaceous palaeogene k pg boundary interval is often penetrated by burrows which may obscure stratigraphic and micropalaeontological records leading to misinterpretations of the sequence of events spanning the k pg boundary here we assess the role of burrowing organisms in the redistribution of benthic foraminifera across the boundary at bidart france and report a strong relationship between the behaviour represented by pre and post k pg trace fossils and their benthic foraminiferal content we further infer a brief interval of eutrophic conditions at the seafloor as reported from other locations which disappeared from the lowermost danian stratigraphic record and is represented only inside post k pg trace fossils hosted in cretaceous strata the combined study of trace fossils and microfossils is a powerful tool in eco stratigraphy and event stratigraphy and can yield important insights into the completeness of the k pg record especially at locations such as bidart where this interval has traditionally been assumed to be complete

diverse patterns of ocean export productivity change across the cretaceous paleogene boundary new insights from biogenic barium 1 one of the best studied aspects of the k pg mass extinction is the decline and subsequent recovery of open ocean export productivity e g the flux of organic matter from the surface to deep ocean some export proxies including surface to deep water 13c gradients and carbonate sedimentation rates indicate a global decline in export productivity triggered by the extinction in contrast benthic foraminiferal and other geochemical productivity proxies suggest spatially and temporally heterogeneous k pg boundary effects here we address these conflicting export productivity patterns using new and compiled measurements of biogenic barium unlike a previous synthesis we find that the boundary effect on export productivity and the timing of recovery varied considerably between different oceanic sites the northeast and southwest atlantic southern ocean and indian ocean records saw export production plummet and remain depressed for 350 thousand to 2 million years biogenic barium and other proxies in the central pacific and some upwelling or neritic atlantic sites indicate the opposite with proxies recording either no change or increased export production in the early paleocene our results suggest that widespread declines in surface to deep ocean 13c do not record a global decrease in export productivity rather independent proxies including barium and other geochemical proxies and benthic community structure indicate that some regions were characterized by maintained or rapidly recovered organic flux from the surface ocean to the deep seafloor while other regions had profound reductions in export productivity that persisted long into the paleocene

tsunami waveform inversion for sea surface displacement following the 2011 tohoku earthquake importance of dispersion and source kinematics this paper considers the importance of model parameterization including dispersion source kinematics and source discretization in tsunami source inversion we implement single and multiple time window methods for dispersive and nondispersive wave propagation to estimate source models for the tsunami generated by the 2011 tohoku oki earthquake our source model is described by sea surface displacement instead of fault slip since sea surface displacement accounts for various tsunami generation mechanisms in addition to fault slip the results show that tsunami source models can strongly depend on such model choices particularly when high quality open ocean tsunami waveform data are available we carry out several synthetic inversion tests to validate the method and assess the impact of parameterization including dispersion and variable rupture velocity in data predictions on the inversion results although each of these effects has been considered separately in previous studies we show that it is important to consider them together in order to obtain more meaningful inversion results our results suggest that the discretization of the source the use of dispersive waves and accounting for source kinematics are all important factors in tsunami source inversion of large events such as the tohoku oki earthquake particularly when an extensive set of high quality tsunami waveform recordings are available for the tohoku event a dispersive model with variable rupture velocity results in a profound improvement in waveform fits that justify the higher source complexity and provide a more realistic source model

the large andaman islands earthquake of 26 june 1941 why no significant tsunami we present a modern seismological study of the earthquake of 26 june 1941 in the andaman islands the largest pre 2004 event along that section of the india burma plate boundary despite a large conventional magnitude m text pas 8 1 it generated at best a mediocre tsunami for which no definitive quantitative reports are available we show that the 1941 earthquake took place under the andaman accretionary prism and consisted of a composite event whose nucleating phase had a strike slip mechanism incompatible with a data set of spectral amplitudes of mantle rayleigh and love waves combining this initial phase with a larger normal faulting mechanism can reconcile them with p wave first motions reports of subsidence on the eastern coast of the andaman islands and the small amplitudes of any putative tsunami the small tsunami results from a combination of that mechanism and of a source located under the islands themselves and in shallow water implying a reduction in amplitude under green s law when transitioning to a deeper basin

shelf hypoxia in response to global warming after the cretaceous paleogene boundary impact the chicxulub asteroid impact at the cretaceous paleogene k pg boundary resulted in one of the most abrupt global warming events in the past 100 m y presenting an analogue to current global warming here we present high resolution geochemical micropaleontological and palynological records of the brazos 1 texas usa stevns klint denmark and caravaca spain k pg boundary sections to assess the rapid environmental changes during the global warming following the brief k pg boundary impact winter warming during the first millennia after the impact is associated with hypoxic bottom waters at the studied shelf sites as indicated by molybdenum enrichments causing major stress for benthic communities we attribute this decline in dissolved oxygen to a combination of decreased gas solubility and ocean ventilation resulting from the warming of the sea water and increased oxygen demand in shelf bottom waters due to increased nutrient inputs and associated high productivity

chemical composition of thalassinoides boxwork across the marine k pg boundary of central new jersey u s a thalassinoides isp burrow networks filled with green to dark bluish gray glauconite pellets occur in the cretaceous to paleogene hornerstown formation and in the uppermost 1 2 m of the underlying upper cretaceous navesink and new egypt formations at many central new jersey cretaceous paleogene k pg boundary sections near the base of the hornerstown formation is a renowned bonebed the main fossiliferous layer mfl which contains isolated to articulated cretaceous marine reptiles turtles birds and crocodiles interpreted as a thanatocoenosis we investigated the bulk chemical composition of the burrow fill and surrounding matrix in the largely unconsolidated sections of the k pg interval at two sites inversand and walnridge meirs farm new jersey using a niton xl3t xrf analyzer to place them in proper stratigraphic context bulk matrix zr and ti concentrations decrease up section as a result of transgression deepening and increased distance from source areas in contrast an increase in k is attributed to greater amounts and maturity of the glauconite due to decreasing sedimentation rates zr and ti concentrations in burrow fills below the mfl are virtually the same as in overlying sediments above the mfl and much less than in the surrounding matrix this suggests that burrows in the cretaceous strata were passively filled with paleogene sediments k concentrations of burrow fills are generally intermediate between the high values encountered in the paleogene matrix and the lower values of the cretaceous matrix although this may have resulted from removal of glauconite during bioturbation and burrow filling it is more likely that immature glauconite was sequestered in the burrow fills below the depth of glauconitization before it could attain full maturity therefore burrows originating above the formational contact at or above the mfl penetrate as much as two meters into underlying cretaceous sediments and are passively filled with paleogene sediment burrows originating above the mfl may translocate diagnostic danian microfossils shocked quartz and ir effectively diffusing the k pg boundary this research demonstrates that care must be taken in sampling pervasively bioturbated strata to avoid incorporating stratigraphically younger burrow fill sediments

coseismic slip model of offshore moderate interplate earthquakes on march 9 2011 in tohoku using tsunami waveforms abstract we estimated the coseismic slip distribution associated with the mw 7 2 and 6 5 foreshocks of the 2011 tohoku oki earthquake based on analysis of the tsunami waveform records obtained just above their focal areas the results show that the main rupture areas of each of the foreshocks do not overlap with each other and show a distribution that is complementary to the postseismic slip area of the first mw 7 2 foreshock as well as to the epicenters of smaller earthquakes during foreshock activity after the second largest foreshock seismicity increased in the area between the rupture area of the second largest foreshock and the mainshock epicenter suggesting propagation of aseismic slip towards the mainshock epicenter the calculated stress drop of the second largest foreshock was smaller than the largest one implying strength reduction during the postseismic period of the largest foreshock based on a comparison of coastal tsunami records it is suggested that the asperity ruptured in the m 7 0 earthquake in 1981 ruptured again during the largest foreshock in 2011 but it expanded to the updip side of the 1981 rupture area and became larger in magnitude exemplifying the irregularity of earthquake recurrence in the area

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

three dimensional tsunami generation simulation due to sea bottom deformation and its interpretation based on the linear theory summary the present study investigates the tsunami generation process by using 3 d numerical simulations and the linear potential theory first we evaluate the relation between sea bottom elevation and sea surface elevation as function of source size l sea depth h and source duration t based on 3 d numerical simulations the surface elevation decreases with increasing sea depth and source duration the difference between the sea bottom and the sea surface elevation appears when the source size is smaller than approximately 10 times the sea depth for a short source duration the linear potential theory can precisely predict the numerical simulation results based on the theory we can consider the tsunami generation as two spatial lowpass filter processes in which the cut off wavenumbers are given by the sea depth and the source duration the criteria for small source size and short source duration are given as l 13h and t l 8c respectively where c is the phase velocity of the tsunami we then simulate the tsunami generation of the 1896 sanriku tsunami earthquake japan the simulated sea surface elevation is significantly different from the sea bottom elevation which suggests the need for correction of the sea depth and source duration for the precise evaluation of the initial water height distribution to include these effects in 2 d simulations we can use the impulse response function and add the fractional sea surface uplift within the time step to the sea surface for each time step

tsunami waveform inversion incorporating permanent seafloor deformation and its application to tsunami forecasting 1 we propose a method of tsunami waveform inversion to accurately estimate a tsunami source by incorporating the effect of permanent seafloor deformation recorded by ocean bottom pressure gauges obpgs within the source region we developed a general expression of water depth fluctuation recorded at an obpg following seafloor deformation of arbitrary spatiotemporal distribution by assuming that coseismic rupture propagates with infinite velocity the general expression can be reduced to an equation relating observed obpg waveforms to initial sea surface displacement at the source by using a green s function consisting of two terms the green s function used in regular tsunami inversion and a correction term to account for water depth change in response to permanent seafloor deformation by using the two term green s functions the effect of seafloor deformation can be taken into account in tsunami source estimation we applied the revised inversion method to observations of coseismic seafloor deformation and tsunami during the 2003 tokachi oki earthquake mw 8 3 at two obpg stations near the kuril trench the tsunami source model we estimated is consistent with models previously derived using various other geophysical data sets furthermore the coastal tsunami waveforms we modeled match the observed tsunami well forecasts of tsunami arrival times and first peak amplitudes by our method can be obtained 20 min after an earthquake and can be provided to the coastal communities nearest to the source with a lead time of 10 min

using polarized raman spectroscopy to study the stress gradient in mineral systems with anomalous birefringence polarized raman spectroscopy was applied to garnet hosts which exhibit anomalous birefringence around inclusions of zircon and quartz to elucidate the spatial distribution of the anisotropic strain fields in the vicinity of the host inclusion boundary we show that there is a direct relationship between the stress induced birefringence and the raman scattering generated by the fully symmetric phonon modes the a1g modes in cubic crystals our experimental results coupled with selected finite element models show that the ratio between the measured raman peak intensity collected in cross and parallel polarized scattering geometries of totally symmetric modes represents a useful tool to constrain the radial stress profile in the host around the inclusions further we demonstrate how group theoretical considerations and tensor analysis of the morphic effect external field induced change of the symmetry on the phonons and the optical properties of the host can help to derive useful information on the symmetry of the stress field finally we show experimentally that under the same amount of applied stress this approach is more sensitive than the commonly used approach of measuring differences in phonon frequencies and provides better opportunities to map the spatial variations of strain this approach is an alternative technique to study structural phenomena associated with anomalous birefringence in host crystals surrounding stressed inclusions and could be applied to other systems in which similar optical effects are observed

rupture process of the 1944 tonankai earthquake ms 8 1 from the inversion of teleseismic and regional seismograms 1 we digitized teleseismic and regional records of the 1944 tonankai earthquake we used the multiple time window method to invert these records for the spatial and temporal distribution of slip and rake we assume a 220 140 km fault with a spacing of 20 20 km and a maximum rupture velocity of 2 5 km s the inversion resolved an asperity along the accretionary wedge and under the shima and atsumi peninsulas the rupture propagated from southwest to northeast and there was little slip near the hypocenter consistent with the absence of uplift in the overlying submarine forearc basin the peak slip is 2 3 m and the total seismic moment is 2 4 1028 dyn cm mw 8 2 we compared the predicted and observed vertical geodetic displacements and inferred that the limit of rupture is consistent with the change from subsidence to uplift west of the atsumi peninsula this suggested that the earthquake did not rupture the plate interface in the tokai gap we modeled the tsunami using sea bottom displacements generated from this slip model the tide gauge amplitudes and frequency content are consistent with those predicted resolution tests from inverting synthetic seismograms computed using a simplified slip model indicated that the combination of teleseismic and regional data sets best recovers the asperity locations and peak slips given similar station geometry and degrees of freedom an inversion of the synthetic regional data set indicates that slip artifacts can occur early in the rupture process due to many clipped records while the inversion of synthetic teleseismic data set had less resolution and recovered only 50 of the peak slip

the cretaceous palaeogene k p boundary at ain settara tunisia restructuring of benthic foraminiferal assemblages benthic foraminiferal assemblages in contrast to planktic foraminifera generally did not suffer mass extinctions at the cretaceous palaeogene k p boundary extinctions were fewer in deeper water however the outer shelf upper bathyal section at ain settara tunisia records a dramatic change in the structure of benthic foraminiferal assemblages across the k p boundary at the level of extinction of planktic assemblages and enrichment in ir and other geochemical anomalies highly diversified low dominance upper maastrichtian assemblages with infaunal and epifaunal morphogroups were suddenly replaced by taxonomically impoverished assemblages strongly dominated by epifaunal morphogroups this extinction or temporary emigration of most infaunal morphogroups is interpreted to be the result of a sudden breakdown in food supply this in turn is the consequence of a sudden collapse in primary productivity probably resulting from the impact of the k p asteroid

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

changes in the pelagic fine fraction carbonate sedimentation during the cretaceous paleocene transition contribution of the separation technique to the study of bidart section abstract the bidart section southwestern france displays an almost complete late maastrichtian early danian transition as the cretaceous paleocene k p crisis mainly affects carbonate producers the aim of this study is to precisely evaluate the evolution of pelagic sediments composition across the boundary a new protocol for separation of fine carbonates into discrete size fractions was used 1 to precisely evaluate in weight of carbonate and not only number of particles per gram of rock the contribution of each carbonate component type foraminifera calcareous nannofossils and nonbiogenic carbonates calcite microparticles and calcareous macrocrystals and 2 to measure their isotopic signature and thus constrain the origin of these carbonate particles the maastrichtian pelagic carbonates are mostly biogenic 70 of the bulk carbonate but also contain nonbiogenic carbonates calcite microparticles 4 m due to their isotopic signature calcite microparticles cannot result from fragmentation and partial dissolution of biogenic remains and the most likely origin appears to be early diagenetic processes and or export from shallow water platforms the calcareous macrocrystals derive from an early diagenetic process the lowermost danian sediments are dominated by nonbiogenic carbonates between 50 and 80 of the bulk carbonate nevertheless two kinds of biogenic components are present thoracosphaera operculata and maastrichtian like calcareous nannofossils thoracosphaera operculata is an opportunistic calcareous dinoflagellate which frequently occurs at high abundances in basal danian sediments and is certainly in situ this is confirmed by it showing a danian isotopic signature the maastrichtian like calcareous nannofossils are nannofossils of taxa that indisputably occur in the maastrichtian but which do not occur consistently in later danian strata they show a maastrichtian type isotopic signature which strongly supports the inference that they are mainly reworked from the maastrichtian this study shows that nonbiogenic carbonates are important components of the pelagic carbonate even during periods of normal sedimentation in the crisis interval the biogenic carbonate production drops sharply while calcite microparticles and carbonate macrocrystals remain almost unaffected and represent the major part of the carbonate in the earliest danian sediments finally the sediments return to a composition similar to that of the maastrichtian in m pseudobulloides foraminifera zone

estimate of the tsunami source of the 1992 nicaraguan earthquake from tsunami data the nicaraguan earthquake of september 2 1992 excited large tsunamis which caused significant damage along the nicaraguan coasts some of the inhabitants felt only minimal shock before the tsunami arrived indicating that excitation of short period seismic waves was very small numerical simulation with the initial tsunami source estimated by the seismic data is carried out to study the characteristics of the tsunami source by comparing the calculated data with the measured data along the nicaraguan coast finding of the comparison shows that the dislocation of the fault estimated from the measured data is 5 6 to 10 0 times larger than that from seismic data the tsunami source area which is 200km in length 100km in width is used to explain the distribution of measured tsunami heights along the coast and the wave period as shown in the tide record at corinto the effect of rise time on tsunami excitation indicates a slow process which corresponds with the seismic waves this event falls under the tsunami earthquake category to produces anomalously large tsunamis relative to earthquake magnitude

seismic and tsunami wave propagation of the 2011 off the pacific coast of tohoku earthquake as inferred from the tsunami coupled finite difference simulation abstract the 2011 tohoku earthquake m 9 0 caused significant hazards including strong ground motion coseismic ground deformation and tsunamis for a deeper understanding of these phenomena we conducted a large scale parallel computer simulation by means of the finite difference method fdm with newly developed tsunami coupled equations of motion this method is based on the equations of motion for an elastic medium treating seawater as elastic material having zero s wave velocity tsunami waves are included by taking into account gravity and their equilibrium with the pressure gradient an effective method of fdm simulation using the state of the art massively parallelized k computer is also studied with the use of a 3d layered velocity structure that includes topography and bathymetry basement structure moho depth and plate boundaries and use of the appropriate source rupture model based on joint inversion of seismic waves and geodetic observations the simulated seismic waves demonstrate anomalous seismic wave propagation by the thick 3d basin structure inland we also found that the sea column acts as a strong absorber of seismic waves for shallow up dip slip on the ocean side coseismic deformation and tsunamis are dynamically generated in this simulation tsunami attacks on the subsided pacific coast are simulated without any additional assumptions we also modeled the tsunami and seismic records of ocean bottom pressure gauges above the fault because sea bottom tsunami and seismic observation is powerful but very complex recording both seismic and tsunami waves the use of these coupled numerical simulations has great potential for resolving complex source fault rupture processes in a 3d heterogeneous structure online material mpeg movies of fault slip seismic wave propagation seafloor and ground displacement and tsunamic propagation

sea surface temperature variability in the subpolar atlantic over the last two millennia 1 a decadal resolution time series of sea surface temperature sst spanning the last two millennia is reconstructed by combining a proxy record from a new sediment sequence with previously published data from core md99 2275 north of iceland the alkenone based sst reconstruction is validated with historic observational data and compared to a new similar temporal resolution reconstruction obtained from sediment core rapid21 3k in the subpolar north atlantic the two sst paleorecords show consistent multidecadal scale coolings throughout the interval and similar expressions during the contrasted climatic periods colloquially known as the medieval climatic anomaly mca and little ice age lia in order to further understand the temporal and spatial sst variations and investigate the influence of natural forcings on the observed sst changes during the last millennium we compare our time series to simulations using the institut pierre simon laplace ipslcm4 v2 climate model this comparison highlights the potential importance of volcanism as a natural forcing driving coherent abrupt cooling events captured in the subpolar north atlantic records

tsunami energy ocean bottom pressure and hydrodynamic force from stochastic bottom displacement tsunami generation and propagation due to a randomly fluctuating of submarine earthquake modeled by vertical time dependent of a stochastic bottom displacement are investigated the increase in oscillations and amplitude in the free surface elevation are controlled by the noise intensity parameter of the stochastic bottom displacement evolution of kinetic and potential energy of the resulting waves by the stochastic bottom displacement is examined exchange between potential and kinetic energy was achieved in the propagation process the dynamic ocean bottom pressure during tsunami generation is investigated as the vertical displacement of the stochastic bottom increases the peak amplitude of the ocean bottom pressure increases through the dynamic effect time series of the maximum tsunami wave amplitude kinetic and potential energy wave and ocean bottom pressure gauges and the hydrodynamic force caused by the stochastic source model under the effect of the water depth of the ocean are investigated

simulation of tsunami induced by dynamic displacement of seabed due to seismic faulting in conventional tsunami simulation techniques simplifications have been employed by neglecting the dynamic seabed displacement resulting from fracturing of a seismic fault and considering only the static contribution the water layer is also assumed to be incompressible regardless of its acoustic effects they should be reconsidered in light of the state of the art technology because considerable discrepancies between numerical simulations and actual observation have been pointed out regarding for example arrival time and wave height in the present study tsunami simulation is conducted without using these kinds of simplification taking into account both the dynamic displacement and acoustic effects as a result thus simulated tsunamis are found to be remarkably larger in the wave height especially in the near fault area where these two effects are superposed in far field however tsunamis thus simulated are likely to show little difference in the wave height but show considerable difference in the arrival time in addition the present dynamic analysis is capable of simulating the water wave induced by the rayleigh wave propagated along the seabed

recovery of the deep sea floor after the cretaceous paleogene boundary event the benthic foraminiferal record in the basque cantabrian basin and in south eastern spain abstract a detailed analysis of the upper cretaceous and lower paleogene benthic foraminiferal assemblages 63 m from the middle bathyal loya section basque cantabrian basin southwestern france has been carried out the benthic foraminiferal and palaeoenvironmental turnover across the k pg boundary at loya has been compared to that observed in the nearby bidart section both sections exhibit mesotrophic conditions in the uppermost maastrichtian and a drastic decrease in the nutrient supply to the sea floor in coincidence with the k pg boundary moreover a faunal recovery of the assemblages is observed through the lowermost danian the pattern of faunal and palaeoenvironmental recovery in the basque cantabrian basin has been compared to that observed in the middle bathyal agost and caravaca sections south eastern spain where a similar decrease in the food supply to the sea floor is observed in coincidence with the k pg boundary however whereas low oxygen conditions have been recorded in the lowermost danian in these two sections no evidence for oxygen deficiency has been found in the basque cantabrian basin thus pointing to the regional and not global nature of low oxygen conditions following the k pg boundary event benthic foraminifera from the g cretacea biozone suggest environmental instability in the basque cantabrian basin and in southeastern spain such environmental stress has been related not only to the collapse of the food web due to the extinction of calcareous primary producers but also to a rapidly changing food supply driven by phytoplankton blooms although stabilization of the ecosystems in surface waters probably occurred towards the upper part of the g cretacea biozone data available from the ps pseudobulloides biozone at bidart and agost indicate that food supply to the benthos had not completely recovered at least 200 kyr after the k pg boundary

opportunistic behaviour after the toarcian oceanic anoxic event the trace fossil halimedides abstract we present an analysis of the first well documented record of the trace fossil halimedides in lower jurassic toarcian sediments from the west iberian palaeomargin lusitanian basin portugal the abundant and well preserved specimens allow a detailed ichnological characterization supporting interpretation of the associated palaeoenvironmental conditions in terms of substrate consistency firmgrounds food availability and ethology of tracemaker agrichnial sequestrichnia behaviour the appearance of this enigmatic trace is just after the toarcian oceanic anoxic event t oae in agreement with previous records associated with oceanic anoxic events as the oae 1 and oae 2 however in the case study oxygenation at the seafloor can be discarded as the major factor inducing colonization by halimedides tracemakers the rapid appearance of this trace after the t oae is related to the opportunistic behaviour of the tracemaker agrichnial sequestrichnia behaviour capturing and storing food particles together with efficient microbial gardening favoured rapid colonization of the comparatively oligotrophic seafloor in a transgressive context the record of halimedides could be appraised as a tool to evidence significant palaeoenvironmental changes such as those associated with bio events