cyclostratigraphic and δ13c record of the lower cretaceous adriatic platform croatia assessment of milankovitch forcing abstract the 700 m thick hauterivian to albian section from the interior of the large adriatic platform is exposed on mljet and korcula islands croatia the cyclic platform consists of meter scale parasequences bundled into parasequence sets superbundles and then into breccia bounded depositional sequences spectral analysis of time series cycle number vs cycle thickness shows peaks in the short term eccentricity 95 to 130 kyr bands and 160 to 200 kyr bands isotope samples from micrite matrix of mudstone and wackestone have 13c values generally from 1 5 to 2 vpdb and 18o from 1 to 3 5 vpdb adriatic platform 13c values are shifted 2 vpdb more negative than marine pelagic values a 13c and 18o meteoric signal is limited to just beneath sequence boundaries suggesting that the isotopic shift is due mainly to marine phreatic and synorogenic burial diagenesis major excursions on the 5 point smoothed 13c profile of the adriatic platform tied biostratigraphically to 13c curves from pelagic sections include the oceanic anoxic events oae1a 1b and 1c time series constructed from 13c values unsmoothed data vs stratigraphic position show peaks in the milankovitch band especially short term eccentricity most positive peaks are near parasequence set boundaries 50 to 60 and regressive parts of parasequences 20 although diagenetically shifted the 13c record retains a highly clipped memory of astronomically driven global 13c fluctuations albeit modified by platform water restriction during cyclic deposition

steryl ethers in a valanginian claystone molecular evidence for cooler waters in the central pacific during the early cretaceous abstract coring on shatsky rise by ocean drilling project leg 198 recovered sediments rich in organic matter 2 0 corg from three time intervals the early aptian corresponding to oceanic anoxic event oae 1a the valanginian and the berriasian episodes of enhanced sequestration of organic matter during the valanginian are well documented in the tethyan realm notably those associated with a positive 13c isotopic excursion and with changes in plankton assemblages including a demise in nannoconids the 13c excursion has been previously reported in the pacific but the occurrence of valanginian sediments rich in organic matter 1 corg is unprecedented a distinctive feature of the biomarker composition of these valanginian sediments at shatsky rise is the presence of a suite of steryl ethers which extends the temporal record of these compounds from the neogene to the early cretaceous the biological source of steryl ethers remains enigmatic although the sedimentary occurrences of these compounds in quaternary and neogene environments characterized by cool water high seasonal productivity and or nutrient enrichment by upwelling in combination with their liquid crystal properties raise the possibility that they may represent storage lipids akin to wax esters and triacylglycerols prior occurrences of steryl ethers suggest that their presence in the valanginian may reflect an oceanic environment characterized by upwelling consistent with the likely position of shatsky rise within the equatorial divergence zone of the pacific during the early cretaceous alternatively or in addition the appearance of these compounds may represent a biological response to cooler temperatures and thereby augment evidence for global cooling during the early valanginian consistent with independent paleontological evidence for contemporaneous upwelling induced increases in productivity in the western atlantic

high resolution chemo and biostratigraphic records of the early aptian oceanic anoxic event in cantabria n spain palaeoceanographic and palaeoclimatic implications abstract during the early aptian major palaeoenvironmental changes occurred leading to an oceanic anoxic event oae 1a and a perturbation of the global carbon cycle new detailed litho bio and chemostratigraphic toc 13ccarb 13corg records of two superbly exposed and expanded lower aptian sections in cantabria la florida and cuchia allow to recognize the expression of the oae 1a in shallow shelf environments of northern spain the succession consists of shallow platform limestones that include a marly unit patrocinio formation the deposition of which occurred mostly at the onset of the oae 1a 120 5 ma this study presents a new integrated biostratigraphy based on ammonites planktonic foraminifera calcareous nannofossils and palynomorphs that allows an accurate age resolution of the succession the marly unit records an abrupt negative 13c excursion in both bulk organic matter up to 5 and carbonate up to 6 mean 3 as has been already observed at the onset of the oae 1a in other lower aptian deposits worldwide in detail however the negative excursion presents two minima in the studied sections this negative spike is confidently attributed to the upper half of the hayesites irregularis nannofossil zone to the upper part of the blowiella blowi foraminiferal zone and to the middle upper part of the deshayesites weissi ammonite zone a third negative excursion occurs at the base of the rhagodiscus angustus nannofossil zone which may be correlatable with the dufrenoyia furcata ammonite zone this data set refines the age of the oae 1a and reveals the existence of a stratigraphic gap in the westernmost margin of the basque cantabrian basin that covers at least a portion of the upper part of the early aptian sedimentary facies and quantitative analysis of palynomorphs and nannofossils document significant environmental changes associated with the oae 1a compositional changes of neritic carbonates and calcareous nannofossils data indicate the occurrence of a biocalcification crisis inferred to have been related to co2 induced changes in seawater chemistry and palynomorphs identify a thermal maximum followed by a cooling phase the latter show a classopollis maximum during the oae 1a which is followed by a decrease in classopollis and an increase of bisaccate pollen after the event

observing coseismic gravity change from the japan tohoku oki 2011 earthquake with goce gravity gradiometry the japan tohoku oki earthquake 9 0 mw of 11 march 2011 has left signatures in the earth s gravity field that are detectable by data of the gravity field recovery and climate experiment grace mission because the european space agency s esa satellite gravity mission gravity field and steady state ocean circulation explorer goce launched in 2009 aims at high spatial resolution its measurements could complement the grace information on coseismic gravity changes although time variable gravity was not foreseen as goal of the goce mission we modeled the coseismic earthquake geoid signal and converted this signal to vertical gravity gradients at goce satellite altitude we combined the single gradient observations in a novel way reducing the noise level required to detect the coseismic gravity change subtracted a global gravity model and applied tailored outlier detection to the resulting gradient residuals furthermore the measured gradients were along track filtered using different gradient bandwidths where in the space domain gaussian smoothing has been applied one year periods before and after earthquake occurrence have been compared with the modeled gradients the comparison reveals that the earthquake signal is well above the accuracy of the vertical gravity gradients at orbital height moreover the obtained signal from goce shows a 1 3 times higher amplitude compared with the modeled signal besides the statistical significance of the obtained signal it has a high spatial correlation of 0 7 with the forward modeled signal we conclude therefore that the coseismic gravity change of the japan tohoku oki earthquake left a statistically significant signal in the goce measured gravity gradients

coseismic and postseismic deformation of the 2011 tohoku oki earthquake constrained by grace gravimetry 1 spaceborne gravimetry data from the gravity recovery and climate experiment grace are processed using spatio spectral slepian localization analysis enabling the high resolution detection of permanent gravity change associated with both coseismic and postseismic deformation resulting from the great 11 march 2011 mw 9 0 tohoku oki earthquake the grace observations are then used in a geophysical inversion to estimate a new slip model containing both coseismic slip and after slip the grace estimated moment for the total slip up to the end of july 2011 is estimated as 4 59 0 49 1022 n m equivalent to a composite mw of 9 07 0 65 if the moment for the tohoku oki main shock is assumed to be 3 8 1022 n m the contribution from the after slip is estimated to be 3 0 1021 12 8 1021 n m in good agreement with a postseismic slip model inverted from gps data we conclude that grace data provide an independent constraint to quantify co and post seismic deformation for the tohoku oki event

correlation of early cretaceous carbon isotope stratigraphy and platform drowning events a possible link the early cretaceous carbonate carbon isotope record is marked by three positive high amplitude 1 5 excursions each covering time spans of more than 106 years they are of late valanginian hauterivian and early and late aptian age in a case study along a transect across the western tethys ocean we identified a coincidence between 13c excursions black shale formation and widespread carbonate platform drowning events we conclude that the 13c excursions reflect a change in partitioning of carbon between the organic and carbonate carbon sinks which was triggered by climate induced ecological changes in cretaceous pelagic and neritic environments episodes of intensified greenhouse climate conditions led to an increase in weathering erosion and runoff rates and to elevated nutrient transfer rates from continents into oceans the resulting increase in oceanic nutrient levels favoured marine phytoplankton production and black shale deposition while conditions for carbonate producing biotas became unfavourable partial choking of carbonate production along river influenced coasts resulted in widespread carbonate platform drowning during times of sea level rise in the valanginian and aptian widespread contemporaneous black shale deposits and drowned carbonate platforms therefore reflect the contrasting response of the marine organic and carbonate carbon pumps to nutrient enhanced phytoplankton productivity the change in marine carbon partitioning is mirrored in a shift of the 13c record towards more positive values the transition to the 13c peak values lasted up to several hundred thousand years the peaks of the excursions also covering a time span of up to several hundred thousand years reflect a new stabilisation of the carbon partitioning between carbonate and organic carbon sinks a renewed intensification of carbonate sedimentation under mesotrophic conditions was facilitated by stabilisation of the sea level rise at a high level decreasing 13c values record increasing carbonate carbon burial rates at constant or decreasing organic carbon accumulation rates these changes contributed to the stabilisation of the marine carbon budget and the global carbon cycle up to millions of years after its initial perturbation

evidence of viscoelastic deformation following the 2011 tohoku oki earthquake revealed from seafloor geodetic observation the gps acoustic seafloor positioning has detected significant postseismic movements after the 2011 tohoku oki earthquake m9 0 just above the source region off the pacific coast of eastern japan in contrast to the coastal global navigation satellite systems sites where trenchward upward movements were reported the offshore sites above the main rupture zone in the northern part of the source region exhibit landward displacements of tens of centimeters with significant subsidence from almost 3 years of repeated observations at the sites above around the edge of the main rupture zone smaller amount of trench normal movements was found although the terrestrial movements were reasonably interpreted by afterslip beneath the coastal area these offshore results are rather consistent with effects predicted from viscoelastic relaxation in the upper mantle providing definitive evidence of its occurrence on the other hand the results in the southern part of the source region imply superposition of effects from viscoelastic relaxation and afterslip

global positioning system gps and gps acoustic observations insight into slip along the subduction zones around japan the global positioning system gps is one of the most powerful tools available for observation of earth s surface deformation in particular coseismic postseismic slow transient and interseismic deformation have all been observed globally by gps over the past two decades especially in subduction zones moreover gps acoustic techniques have been developed for practical use in the past decade allowing observation of offshore deformation immediately above slip regions here we describe the application of gps and gps acoustic observations to the detection of deformation due to plate boundary slip for interplate earthquakes as well as afterslip and slow slip events in subduction zones around japan where geodetic data coverage is particularly dense the data demonstrate temporally variable strain accumulation in the source region of the 2011 mw 9 0 tohoku oki earthquake and observation of the huge slip of the tohoku oki earthquake near the trench using gps acoustic methods has considerably advanced o

propagation of slow slip leading up to the 2011 mw 9 0 tohoku oki earthquake many large earthquakes are preceded by one or more foreshocks but it is unclear how these foreshocks relate to the nucleation process of the mainshock on the basis of an earthquake catalog created using a waveform correlation technique we identified two distinct sequences of foreshocks migrating at rates of 2 to 10 kilometers per day along the trench axis toward the epicenter of the 2011 moment magnitude mw 9 0 tohoku oki earthquake in japan the time history of quasi static slip along the plate interface based on small repeating earthquakes that were part of the migrating seismicity suggests that two sequences involved slow slip transients propagating toward the initial rupture point the second sequence which involved large slip rates may have caused substantial stress loading prompting the unstable dynamic rupture of the mainshock

grace measurements of mass variability in the earth system monthly gravity field estimates made by the twin gravity recovery and climate experiment grace satellites have a geoid height accuracy of 2 to 3 millimeters at a spatial resolution as small as 400 kilometers the annual cycle in the geoid variations up to 10 millimeters in some regions peaked predominantly in the spring and fall seasons geoid variations observed over south america that can be largely attributed to surface water and groundwater changes show a clear separation between the large amazon watershed and the smaller watersheds to the north such observations will help hydrologists to connect processes at traditional length scales tens of kilometers or less to those at regional and global scales

carbon isotope stratigraphy in shallow water carbonates implications for cretaceous black shale deposition a barremian to albian succession on mount kanala part of a tethyan isolated carbonate platform was investigated for its 13c variations the limestone sequence is composed of a series of peritidal shallowing upward cycles with clear petrographic evidence for strong early diagenetic overprinting related to repeated subaerial exposure despite significant impact of diagenesis the observed changes in 13c can be very well correlated with deep water sections from different ocean basins and shallow water carbonate platforms in the middle east this lends further support to the applicability of 13c variations for stratigraphic purposes in shallow water limestones using the 13c signal time resolution in lower cretaceous platform carbonates can be significantly increased independent of bio zonations often hampered by ecological variability cyclostratigraphic analysis of the aptian part of the section shows that strong positive excursions of the cumulative departure from mean cycle thickness of the peritidal shallowing upward cycles coincide with global positive 13c excursions this and the fact that positive shifts in the 13c record are preserved within shallow water limestones provide evidence that black shale accumulation in the ocean basins occurred during sea level rise and flooding of platform tops integration of carbon isotope cyclo and sequence stratigraphic results from different carbonate platforms indicate that strong positive global 13c shifts and concurrent organic carbon burial during black shale deposition are ultimately caused by rapid rises of eustatic sea level hence the rate of change of eustatic sea level is considered to play a crucial role in black shale accumulation in the global ocean basins during the cretaceous

a viscous rotational model for wave overtopping over marine structure wave overtopping problems continue to require more attention due to the complexity of the physical process and the lack of available predictive models in a recent experimental study on the kinematics of wave overtopping on marine structure by lee zhuang and chang 1993 it was found that the overtopping wave constitutes a jet like water mass impacting the shoreward region of the breakwater this jet like water mass induces strong vortices and large water particle velocities in both the horizontal and vertical direction in the shoreward region behind the marine structure the large rotational velocity field is capable of removing the armor units of the breakwater and scouring the bed in the shoreward region of the breakwater in the study of zhuang chang and lee 1994 a numerical model capable of generating the rotational velocity field in the vicinity of the shoreward face of the breakwater was proposed this paper presents the computation results from a refined viscous rotational model and their comparisons with newly acquired experimental data

carbon isotope stratigraphy of the upper kharaib and shuaiba formations implications for the early cretaceous evolution of the arabian gulf region the carbon isotope profiles of shallow marine carbonates from the barremian aptian kharaib and shuaiba formations of the arabian gulf region range between 0 5 and 7 pmil dgr13c pdb peedee belemnite systematic variations can be correlated with isotope profiles reported from tethyan pelagic limestone sequences the detailed correspondence between the isotopic signature of the relatively well dated pelagic limestones and the poorly dated shallow water limestones from the arabian gulf region suggests that global marine carbon isotope changes apparently affected deep sea and shallow water carbonate sediments similarly and at a similar time resolution although oxygen isotopes have been reset during diagenesis carbon isotopes appear to have maintained their primary marine signature through time no evidence has been found to connect carbon isotope trends to subaerial exposure or later meteoric diagenesis in combination with other data the investigated carbon isotope profiles can be used for basin to platform and regional correlations beyond the current resolution of biostratigraphy in shallow water limestones carbon isotope stratigraphy confirms significant hiatuses in the investigated shallow water carbonate sequences using carbon isotope trends as a proxy for sea level fluctuations the carbon isotope cycles of the late early cretaceous of the arabian gulf region may represent four cycles of rising and falling sea level with a duration corresponding to that of third order sea level fluctuations regional correlations derived from isotope trends provide a scenario for the larger scale stratigraphic evolution of the arabian peninsula during the end of the early cretaceous differential rates of aggradation between realms influenced by siliciclastics and those characterized by siliciclastic poor clean carbonate deposition apparently caused the development of a pronounced basin platform topography during the early aptian shuaiba intrashelf basin and platform

biogeochemical assessment of sources of organic matter and paleoproductivity during the early aptian oceanic anoxic event at shatsky rise odp leg 198 this study investigates organic rich sedimentary sequences deposited during the early aptian oceanic anoxic event oae1a at sites 1207 and 1213 on shatsky rise odp leg 198 in the west central pacific biomarker analyses provide evidence of the algal and bacterial origin of organic matter om in these sediments where the abundance of steroidal components particularly sterenes and sterones suggests that the om includes major contributions from eukaryotic sources in an environment characterized by high phytoplankton productivity the presence of alkenones at site 1213b is diagnostic of om derived from representatives of haptophyte algae among the calcareous nannoplankton and their 13c values average 31 6 are consistent with those expected during elevated pco2 the occurrence and prominence of 2 methylhopanes and 2 methylhopanones indicates significant contributions to the om from cyanobacteria which are also likely contributors of hopanoids based on their 13c compositions these biomarker data suggest that oceanic conditions perhaps nitrate or iron limited were conducive to cyanobacteria production during oae1a which appears to distinguish this event from other cretaceous oae

cretaceous oceanic anoxic events and radially elongated chambered planktonic foraminifera paleoecological and paleoceanographic implications chamber elongation is a recurring morphological character in cretaceous and cenozoic planktonic foraminiferal evolution suggesting that the clavate body plan takes advantage through particular environmental conditions cretaceous planktonic foraminifera bearing radially elongated chambers become repeatedly a consistent component of assemblages in correspondence with the deposition of remarkable organic layers that record the effects of oceanic anoxic events oaes due to this apparent correspondence chamber elongation has been recently interpreted as an adaptation to low oxygen levels in the upper water column the paleoceanographic significance of planktonic foraminifera with radially elongated chambers remains however unclear we investigated in great detail the distribution and abundance of elongated chambered planktonic foraminifera in an interval of about 40 myr across the cretaceous oaes in different well dated sections the increased abundance of planktonic foraminifera with elongated chambers can be a markedly evident feature across the faraoni the selli and the bonarelli oaes however each event shows its own peculiarities remarkably the first radiation of the cretaceous elongated chambered morphotypes just predates the latest hauterivian faraoni event the selli event records the greatest diversification number of species of the group bearing elongated chambers however this was a period of great diversification in the planktonic foraminifera this evidence may suggest that radiation of these forms was driven by more than upper water column anoxia per se e g increased upper water column stratification greater productivity and or greater seasonality the albian oae1b oae1c and oae1d display the lowest abundance and diversity of this group conversely according to the available data the first appearances of the species muricohedbergella simplex and of the genus schackoina occur close to the oae1b and oae1d respectively in the italian record the relative abundance of radially elongated chambered forms appears to be larger before the onset of the bonarelli event with respect to the selli event the pattern involving this group across the bonarelli event appears more regular thus indicating that the onset and the end of the oae2 depend on very powerful global factors and are less influenced by local aspects we speculate that the relative abundance of planktonic foraminifera with radially elongated chambers may be proportional to the strength of the environmental perturbation related to the oaes thus reinforcing the idea that the ecological perturbation related to the oae2 was more severe for the former several lines of evidence suggest that water oxygenation could not have been the single controlling factor governing the development of elongate chambers the role of availability of food and the nature of food has been so far probably underestimated it is most likely that an interplay of several influential physical chemical and ecological factors i e dissolved oxygen concentration temperature salinity nutrients type of food trace elements was responsible for such a morphological adaptation we document linkages between the distribution abundance morphometric changes and evolution of the cretaceous radially elongated chambered planktonic foraminifera and the major igneous geological geochemical climate nutrification and biotic events and biocalcification trends

the influence of regional factors in the expression of oceanic anoxic event 1a oae1a in the semi restricted organya basin south central pyrenees spain abstract the global occurrence of oxygen deprived conditions in the ocean characterizes the early aptian hence the hallmark of that time interval is the accumulation of organic rich sediments during an episode of severe oxygen deficiency known as oceanic anoxic event 1a oae1a as seen elsewhere in the tethyan domain an overall change in facies marked by increased input of terrigenous material distinguishes the lower aptian in the study area but the nature of the lithologies associated with the organic carbon rich deposits remain dominated by carbonate sediments and are expressed differently with respect to other areas where the occurrence of black shales characterizes oae1a this comparison indicates that significant spatial heterogeneity occurred in sub tethyan basins coeval with the global oceanic event the present work provides a high resolution multi proxy study petrography total inorganic carbon tic total organic carbon toc carbon isotope 13corg clay mineralogy and biomarkers of the upper 155 m of the el pui section organya basin including the record of oae1a the results reveal that oxygenic conditions fluctuated throughout the studied interval with episodes of oxygen depletion that concurred with toc values 1 however petrographic observations molecular biomarkers and redox sensitive trace elements rstes indicate that full anoxia was not achieved the results also provide the first high resolution 13corg profile for the el pui section that replicates in greater detail the carbon isotopic signature reported for the tethyan domain the upper 155 m of the el pui section include expanded and well defined trends of the carbon isotope segments c2 upper part c3 c4 c5 and c6 partial which correlate with other tethyan sections and allow for the recognition of the lower aptian oae1a in the uppermost 40 m of the section such improved high resolution chemostratigraphic curve could contribute to a more precise chronostratigraphic correlation of aptian events in a broader scale

migrating pattern of deformation prior to the tohoku oki earthquake revealed by grace data understanding how and when far field continuous motions lead to giant subduction earthquakes remains a challenge an important limitation comes from an incomplete description of aseismic mass fluxes at depth along plate boundaries here we analyse earth s gravity field variations derived from grace satellite data in a wide space time domain surrounding the mw 9 0 2011 tohoku oki earthquake we show that this earthquake is the extreme expression of initially silent deformation migrating from depth to the surface across the entire subduction system our analysis indeed reveals large scale gravity and mass changes throughout three tectonic plates and connected slabs starting a few months before march 2011 before the tohoku oki earthquake rupture the gravity variations can be explained by aseismic extension of the pacific plate slab at mid upper mantle depth concomitant with increasing seismicity in the shallower slab for more than two years after the rupture the deformation propagated far into the pacific and philippine sea plate interiors suggesting that subduction accelerated along 2 000 km of the plate boundaries in march 2011 this gravitational image of the earthquake s long term dynamics provides unique information on deep and crustal processes over intermediate timescales which could be used in seismic hazard assessment deformation migrated from depth towards the surface in the months leading up to the 2011 tohoku oki earthquake according to analyses of satellite gravity data

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

early aptian paleoenvironmental evolution of the bab basin at the southern neo tethys margin response to global carbon cycle perturbations across ocean anoxic event 1a 1 lower aptian carbonates in the bab basin at the southern neo tethys margin record significant environmental changes across oceanic anoxic event 1a oae1a a long lasting negative shift of carbon isotope ratios 13c associated with a distinct decrease in oxygen isotope ratios 18o in orbitolinid rich carbonates characterizes the onset of oae1a livello selli supporting a hypothesis that a long lasting volcanic co2 emission is the main cause of oae1a inducing global warming a bloom of microencrusters lithocodium and bacinella across the proto bab basin occurred synchronously at the beginning of the subsequent positive 13c excursion responding to the global carbon cycle perturbations the carbonates formed during the oae1a show higher strontium isotope ratios 87sr 86sr compared with those of global seawater this was likely caused by a local influx of isotopically heavier strontium along with nutrients into the proto bab basin these biotic proliferations were triggered by an increased nutrient supply induced by intensified continental weathering due to the global warming suggested by the increase in 18o values spatial variations in the 13c values among sites in the bab basin and its surrounding platform are related to local environmental factors such as the degree of mixing of basin water with ocean water and local removal of 12c by metabolic activity at the platform top the 13c profile of the studied core indicates global removal of organic carbon of oae1a began during the early stage of the second order transgression and lasted until the early stage of the highstand after the oae1a the livello selli corresponds to the early stage of this transgression

phosphogenesis carbon isotope stratigraphy and carbonate platform evolution along the lower cretaceous northern tethyan margin we distinguish three different stages in the evolution of the tithonian late jurassic to aptian early cretaceous northern tethyan carbonate platform 1 carbonate production in the coral oolite mode late tithonian to early valanginian early barremian to early aptian 2 carbonate production in the crinoid bryozoan mode early valanginian haute rivian late aptian and 3 platform retrogradation and destruction condensation and phosphogenesis that is platform drowning early valanginian to early hauterivian middle hauterivian late hauterivian to early barremian early to early late aptian and latest aptian to earliest albian transitions from the coral oolite mode to the crinoid bryozoan mode and consequently to platform drowning may have been driven by increases in nutrient levels on the shelf phases of relative sea level rise in times of carbonate production in the coral oolite mode are named constructive because of the observed platform regeneration following phases of widespread emersion during late sea level highstands in contrast phases of relative sea level rise in times of platform drowning are termed destructive the 13 c stratigraphies obtained from valanginian hauterivian and aptian albian hemipelagic successions beyond the platform correlate well with the early cretaceous pelagic 13 c record positive excursions in the pelagic 13 c record correspond in time to episodes of platform drowning this suggests the existence of a coupling mechanism between changes in the global carbon cycle and platform drowning in our view the early cretaceous crises in carbonate platform growth were the consequence of reinforced greenhouse conditions which may have been triggered by episodes of extensive flood basalt volcanism strong greenhouse conditions may have induced the following chain of feedback mechanisms enabling the biosphere to return to normal conditions climate warming sea level rise accelerated water cycle intensified weathering nutrient mobilization platform destruction increased productivity increased phosphogenesis and carbon burial weakened greenhouse conditions

high frequency moderate to high amplitude sea level oscillations during the late early aptian insights into the mid aptian event galve sub basin spain abstract this paper presents a field based stratigraphic architecture research from the aptian of spain in which high frequency 7 cycles ma moderate to high amplitude 8 127 m sea level oscillations are evidenced by the repeated incision of palaeovalleys in a carbonate platform developed during the late early aptian in a rift setting global eustacy tectonic uplift and mantle dynamic topography are considered as potential mechanisms to explain the observed relative sea level record glacioeustacy is interpreted as the most reliable mechanism to drive the observed sea level oscillations however other mechanisms as oscillations of the groundwater capacity of sedimentary basins and sudden flooding of major a basin as the south atlantic rift are also considered a major cooling event is proposed to occur during the late early aptian as a response to a large scale episode of ignimbritic volcanism increased burial of organic carbon during the aptian oae 1a and a significant demise of carbonate platforms this cooling event is interpreted as the origin for glacioeustatic sea level oscillations during the mid aptian

on the interaction of a solitary wave and a submerged dike abstract the unsteady two dimensional navier stokes equations and the exact free surface boundary conditions were solved to study the interaction of a solitary wave and a submerged dike a piston type wavemaker was set up in the computational domain to produce the incident solitary waves the incident wave and the associated boundary layer flow in a wave tank with a flat bed were compared with the analytical solutions to verify the accuracy of this numerical scheme effects of the incident wave height and the size of the dike on the wave transformation the flow fields and the drag forces on the dike were discussed our numerical results showed that even though the induced local shear stress on the top surface of the dike is large at some particular locations the resultant pressure drag is much larger than the friction drag the primary vortex generated at the lee side of the dike and the secondary vortex at the right toe of the dike may scour the bottom and cause a severe problem for the dike

gravitational gradient changes following the 2004 december 26 sumatra andaman earthquake inferred from grace summary it has been demonstrated that the gravity recovery and climate experiment grace spaceborne gravimetry data are capable of observing coseismic gravity changes resulting from great earthquakes such as the 2004 december 26 sumatra andaman event mw 9 1 9 3 here we show for the first time that refined deformation signals from the 2004 december 26 sumatra andaman earthquake mw 9 1 9 3 together with the 2005 march 28 nias earthquake mw 8 6 can be revealed by deriving the full gravitational gradient tensor from grace monthly gravitational field the grace inferred coseismic gravitational gradient changes agree well with coseismic slip model predictions since the high frequency contents in gravitational field variation can be amplified by deriving the gravitational gradients the grace derived coseismic gravitational gradient changes clearly delineate the fault lines locate significant slips and better define the extent of the coseismic deformation

potential slab deformation and plunge prior to the tohoku iquique and maule earthquakes megathrust earthquakes rupture the shallow plate boundary in subduction zones analysis of seismic activity preceding megathrust quakes in japan and chile reveals deep seismicity that may mark plunging of the slabs prior to main fault rupture

microfacies biostratigraphy and geochemistry of the hemipelagic barremian aptian in north central tunisia influence of the oae 1a on the southern tethys margin upper barremian lower upper aptian hemipelagic deposits of the hamada formation in the djebel serdj area north central tunisia were studied in detail with regard to microfacies biostratigraphy 13 c stratigraphy and geochemistry our data provide insights into the palaeoenvironmental evolution and sea level fluctuations of the tunisian shelf the unusually expanded deposits consist of mud wacke and packstones which reflect mid and outer ramp depositional environments planktonic foraminifer and 13 c stratigraphy allowed us to establish a detailed time frame and the recognition of the lower aptian oceanic anoxic event 1a oae 1a as well as time equivalent deposits of shallowmarine carbonate platform drowning based on our microfacies studies we subdivide the studied sections into four genetic intervals a pre oae 1a interval an oae 1a and platform drowning equivalent interval and a post platform drowning interval we present a 3rd order sea level curve for the tunisian shelf deriving from the results of our microfacies studies deposits of the oae 1a in the sections investigated are characterised by bioclastic wacke and packstones with high abundances of poorly preserved radiolarians and moderately to well preserved planktonic foraminifers suggesting a transgression and an eutrophication of the upper water column scarceness of benthic macrofossils low abundances of small benthic foraminifers and ostracods possibly suggest dysoxic conditions at the seafloor mudstones of the platform drowning time equivalent deposits directly overlying the oae 1a are partly showing a pronounced drop in carbonate content and are scarce of macrofossils 2008 elsevier b v all rights reserved

the 2011 tohoku oki earthquake displacement reaching the trench axis we detected and measured coseismic displacement caused by the 11 march 2011 tohoku oki earthquake moment magnitude mw 9 0 by using multibeam bathymetric surveys the difference between bathymetric data acquired before and after the earthquake revealed that the displacement extended out to the axis of the japan trench suggesting that the fault rupture reached the trench axis the sea floor on the outermost landward area moved about 50 meters horizontally east southeast and 10 meters upward the large horizontal displacement lifted the sea floor by up to 16 meters on the landward slope in addition to the vertical displacement

tsunami run up and draw down on a plane beach tsunami run up and draw down motions on a uniformly sloping beach are evaluated based on fully nonlinear shallow water wave theory the nonlinear equations of mass conservation and linear momentum are first transformed to a single linear hyperbolic equation to solve the problem with arbitrary initial conditions we apply the fourier bessel transform and inversion of the transform leads to the green function representation the solutions in the physical time and space domains are then obtained by numerical integration with this semi analytic solution technique several examples of tsunami run up and draw down motions are presented in particular detailed shoreline motion velocity field and inundation depth on the shore are closely examined it was found that the maximum flow velocity occurs at the moving shoreline and the maximum momentum flux occurs in the vicinity of the extreme draw down location the direction of both the maximum flow velocity and the maximum momentum flux depend on the initial waveform it is in the inshore direction when the initial waveform is predominantly depression and in the offshore direction when the initial waves have a dominant elevation characteristic

geochemistry palaeoenvironments and timing of aptian organic rich beds of the paja formation curiti eastern cordillera colombia at the curiti quarry eastern cordillera of colombia a 23 35 m section includes a 6 3 m interval of organic rich marlstones calcareous clay shales and clay shales devoid of benthic fossils and bioturbation at the base of the paja formation it overlies carbonate ramp deposits of the rosablanca formation with the topmost layer containing reworked and phosphatized assemblages of middle barremian to lowest aptian ammonites of the genera pulchellia gerhardtia toxancycloceras karsteniceras and prodeshayesites high resolution analyses of the section including total inorganic carbon tic 0 09 50 wt total organic carbon toc up to 8 4 and stable carbon isotope measurements 13 c org between 22 05 and 20 47 allow the determination of the stratigraphic relationship between the organic rich level within the paja formation and oceanic anoxic event 1a oae 1a the range of values and the overall pattern of the 13 c org curve are comparable with the lower aptian interval c7 thus the organic rich shale interval of the paja formation at the curiti section showing characteristics of oxygen depleted conditions was deposited after oae 1a which is known to occur between isotopic levels c3 and c6

organic geochemistry stable isotopes and facies analysis of the early aptian oae new records from spain western tethys abstract the early aptian oceanic anoxic event oae1a is a time interval characterized by increased organic carbon accumulation in marine sediments notable sedimentary and biotic changes and abrupt carbon isotope excursions indicative of significant major palaeoenvironmental changes linked to a perturbation in the global carbon cycle here we present the study of four sections recording the oae1a early aptian in spain which are located in two broad basins respectively located in the south and the north of iberia the southern iberian palaeomargin carbonero la frontera and cau sections and the basque cantabrian basin puentenansa section which represent depositional settings ranging from shallow marine distal ramp cau and drowned platform puentenansa to pelagic environments carbonero la frontera biomarker compositions c isotope profiles biostratigraphic data and facies analysis from the four sections are correlated and integrated the c isotope curves all present a clear negative excursion followed by a positive shift the integration of the c isotope curves with the biostratigraphic data has been used to correlate the studied sections and to tentatively identify the eight segments formerly proposed from the alpine domain and subsequently identified in sections worldwide four main groups of compounds are present in all sections n alkanes isoprenoids hopanes and steranes n alkanes and acyclic isoprenoids pristane and phytane are dominant in most samples the hopanes are represented by a range of c 27 to c 35 components with the specific isomers varying amongst the sections due to differences in thermal maturity steranes occur as a range of c 27 c 28 and c 29 isomers whereas diasteranes only occur in the most thermally mature section carbonero other compounds of interest include gammacerane and dinosterane differences in thermal maturity appear to be the first order control on different biomarker assemblages amongst the studied sections the carbonero section is thermally mature whereas the nearby la frontera and cau sections are immature puentenansa has intermediate values organic matter is derived from a range of terrestrial marine and bacterial sources the dominance of the c 29 sterane isomers in all sections suggests a strong contribution from higher plants the presence of gammacerane indicates water column stratification and high c 29 c 30 hopane ratios suggest anoxia at the water sediment interface respectively sedimentologic analysis also suggests anoxic conditions during sedimentation but evidence for strong and persistent water column anoxia is equivocal the correlation of the sections reveals that sedimentation of organic rich facies started earlier in pelagic and later in the shallow marine settings which can be related to an expansion of the favorable conditions for organic matter accumulation and preservation from deep marine waters to shallower platform environments during the development of oae1a

wave deformation and vortex generation in water waves propagating over a submerged dike the navier stokes equations and the exact free surface boundary conditions are solved to simulate wave deformation and vortex generation in water waves propagating over a submerged dike incident waves are generated by a piston type wavemaker set up in the computational domain numerical results are compared with experimental data in order to confirm the validity of the numerical model the fast fourier transform and a wave resolution technique are applied to decompose the transformed waves and the higher harmonics effects of different parameters on wave transformation and vortex generation are studied systematically these parameters include the ursell number the keulegan carpenter number the water depth ratio the reynolds number the length aspect ratio of the dike and the type of dike

ammonite biostratigraphy and organic carbon isotope chemostratigraphy of the early aptian oceanic anoxic event oae 1a in the tethyan himalaya of southern tibet abstract the early aptian oceanic anoxic event oae 1a is well known in the western tethys the north atlantic and the pacific ocean but has not been reported in the eastern tethys to date in this paper we present bulk organic carbon isotope data and ammonite biostratigraphy of a lower aptian succession from the gucuo area southern tibet these findings document the occurrence of the oae 1a for the first time from the eastern tethys the studied sequence can be attributed to the d forbesi and d deshayesi ammonite zones of the lower aptian the 13 c org data can be correlated with published early aptian carbon isotope records from the western tethys and the pacific a distinctive negative carbon isotope excursion of 2 4 in the upper part of the section corresponds to segment c3 of the oae 1a and the following positive excursion correlates to segment c4 the absolute values of the carbon isotope ratio in the gucuo area are higher than those of known sections in the western tethys and equatorial pacific we suggest that diagenetic alteration is the major cause of the higher absolute values in the gucuo area

statistical significance of precursory gravity changes before the 2011 mw 9 0 tohoku oki earthquake author s wang l burgmann r abstract 2019 american geophysical union all rights reserved it is of paramount importance to independently assess the spatiotemporal uniqueness of a proposed regional precursor initiated a few months before the 2011 mw 9 0 tohoku oki earthquake the precursor has been inferred from grace derived gravitational gradient changes and has been interpreted as a large scale aseismic movement of the subducting plate along the japan trench we design a hypothesis test which enables the rigorous assessment of the statistical significance of short term gradient anomalies at any time in any place and the quantitative comparison of the resolved anomalies with the proposed precursory signal we find that the proposed precursory changes are not statistically unique either in time or in space therefore the precursor cannot be attributed to the proposed dynamic acceleration of the subduction process instead such transient features more likely represent temporally correlated grace observation errors or signals associated with other processes

lower aptian carbon isotope stratigraphy from a distal carbonate shelf setting the cau section prebetic zone se spain a n 13 c curve is reported for the latest barremian to early aptian at a section located in the prebetic zone cau section se spain the studied section records a hemipelagic succession of dark shales deposited on a distal carbonate ramp with a high subsidence rate adjacent to shallow carbonate environments the integrated biostratigraphy of the section is based on ammonites planktonic foraminifera and calcareous nannofossils and it has allowed an accurate dating of the succession the n 13 c curve presented shows a distinctive evolution leading to the recognition of three major excursions as well as a subdivision into eight segments which represents an improvement of the current biostratigraphic resolution the correlation both isotopic and biostratigraphical with other well resolved sections is very accurate even at the higher resolution attained correlation with sections with lowresolution biostratigraphic characterisation from shallow platform limestones also gives good results which supports the effectiveness of carbon isotope stratigraphy as a correlation tool

pre and postseismic slow slip surrounding the 2011 tohoku oki earthquake rupture abstract slow aseismic slip that accommodates part of the long term plate motion on subduction megathrusts is thought to be strongly related to the occurrence of large earthquakes on the same fault zone however the temporal evolution and spatial distribution of the aseismic slip before major earthquakes and of accelerated postseismic afterslip are largely unconstrained we estimate cumulative offsets of small repeating earthquakes that are interpreted to reflect the in situ aseismic slip history on the subduction zone offshore northeastern japan these data reveal contrasting aseismic slip patterns between the coseismic rupture area of the mw 9 0 tohoku oki earthquake and surrounding portions of the subduction thrust the rupture area is characterised by low and variable slip rates before 2008 and the slip stopped almost completely after the earthquake the region surrounding the rupture area exhibited higher aseismic fault slip rates before the earthquake and clear postseismic slip of up to 1 6 m within 9 months following the main shock the frictional fault properties and complete relief of ambient stress in the central rupture zone of the main shock probably control the observed distribution the postseismic slip shows a more abrupt increase in the region closer to the source suggesting outwards propagation of afterslip small but distinct increases in the slip rate in the 3 yr before the earthquake near the area of large coseismic slip suggests preseismic unfastening of the locked area in the last stage of the earthquake cycle

stress driven relaxation of heterogeneous upper mantle and time dependent afterslip following the 2011 tohoku earthquake stress driven relaxation of heterogeneous upper mantle and time dependent afterslip following the 2011 tohoku earthquake yan hu 1 roland burgmann 1 naoki uchida 2 paramesh banerjee 3 and jeffrey t freymueller 4 university of california berkeley berkeley ca united states graduate school of science tohoku university japan earth observatory of singapore nanyang technological university singapore singapore university of alaska fairbanks fairbanks ak united states corresponding author yan hu earth and planetary science university of california berkeley 307 mccone hall berkeley ca 94720 usa yhu seismo berkeley edu this article has been accepted for publication and undergone full peer review but has not been through the copyediting typesetting pagination and proofreading process which may lead to differences between this version and the version of record please cite this article as doi 10 1002 2015jb012508 2015 american geophysical union all rights reserved

a lacustrine record of the early aptian climate change by oceanic anoxic event oae 1a in the jiaolai basin eastern china abstract the early aptian climate change resulted in changes in both the ocean and terrestrial ecosystems this global climate change is well documented in marine sediments in the form of the oceanic anoxic event oae 1a but it has rarely been reported from the inland lakes in the east asian continent in this study carbon and oxygen isotopes quantitative palaeosalinity clay mineral composition and contents organic matter content and detrital zircon ages from the shuinan and zhifengzhuang formations in the jiaolai basin were determined to examine whether this global climate change was recorded in inland lakes this study showed that in the early depositional stage of the shuinan formation the paleo lake in the jiaolai basin was a saline lake with long detention and strong sealing the climate of the jiaolai basin became hotter and drier in the early aptian 120 ma and the evaporation increased which increased the palaeosalinity of the shuinan formation high salinity water high temperatures and strong evaporation led to a positive migration of the 13c values the extreme dry and hot climate documented in the black shale of the shuinan formation might serve as a response of inland lakes to oae 1a this study provided not only a lacustrine record of an early aptian global climate change event but also a new perspective to deepen the understanding of the effects of the cretaceous climate change in terrestrial ecosystems

contribution of satellite gravimetry to understanding seismic source processes of the 2011 tohoku oki earthquake 1 the 2011 great tohoku oki earthquake apart from shaking the ground perturbed the motions of satellites orbiting some hundreds km away above the ground such as grace due to coseismic change in the gravity field significant changes in inter satellite distance were observed after the earthquake these unconventional satellite measurements were inverted to examine the earthquake source processes from a radically different perspective that complements the analyses of seismic and geodetic ground recordings we found the average slip located up dip of the hypocenter but within the lower crust as characterized by a limited range of bulk and shear moduli the grace data constrained a group of earthquake source parameters that yield increasing dip 7 16 2 and simultaneously decreasing moment magnitude 9 17 9 02 0 04 with increasing source depth 15 24 km the grace solution includes the cumulative moment released over a month and demonstrates a unique view of the long wavelength gravimetric response to all mass redistribution processes associated with the dynamic rupture and short term postseismic mechanisms to improve our understanding of the physics of megathrusts

months long thousand kilometre scale wobbling before great subduction earthquakes megathrust earthquakes are responsible for some of the most devastating natural disasters1 to better understand the physical mechanisms of earthquake generation subduction zones worldwide are continuously monitored with geophysical instrumentation one key strategy is to install stations that record signals from global navigation satellite systems2 3 gnss enabling us to track the non steady surface motion of the subducting and overriding plates before during and after the largest events4 6 here we use a recently developed trajectory modelling approach7 that is designed to isolate secular tectonic motions from the daily gnss time series to show that the 2010 maule chile moment magnitude 8 8 and 2011 tohoku oki japan moment magnitude 9 0 earthquakes were preceded by reversals of 4 8 millimetres in surface displacement that lasted several months and spanned thousands of kilometres modelling of the surface displacement reversal that occurred before the tohoku oki earthquake suggests an initial slow slip followed by a sudden pulldown of the philippine sea slab so rapid that it caused a viscoelastic rebound across the whole of japan therefore to understand better when large earthquakes are imminent we must consider not only the evolution of plate interface frictional processes but also the dynamic boundary conditions from deeper subduction processes such as sudden densification of metastable slab

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

interaction of non breaking directional random waves with submerged breakwaters the effect of wave irregularity on submerged permeable structures is analyzed existing literature is summarized the relevant theory is presented and theoretical results are compared with existing laboratory data the influence of structure geometry porous material properties and wave characteristics including oblique incidence on the kinematics and dynamics over and inside the breakwater is considered results for unidirectional and multidirectional wave spectra are compared to those obtained for regular waves the model presented reproduces the experimental results fairly well and provides a tool for analyzing several engineering problems such as breakwater stability and breakwater performance

carbon isotope stratigraphy a tool for basin to carbonate platform correlation the early cretaceous carbonate carbon isotope stratigraphy established in pelagic limestones is marked by several pronounced excursions towards positive 13c values we investigated a biostratigraphically and palaeomagnetically calibrated aptian section to see whether c isotope stratigraphy could be recognized in shallow water carbonates the chosen carbonate platform sections are located in southern italy and have been dated by biostratigraphy bulk samples chosen from the barremian albian part of the sequence were analysed for their o and c isotope compositions the c isotope curve established shows two major positive excursions which can be correlated with the synchronous and globally recognized aptian c isotope events the data provide evidence that c isotope stratigraphy can be used as a powerful correlation tool between pelagic and shallow water limestone sequences

the palaeoceanographic crisis of the early aptian oae 1a in the vocontian basin se france abstract the vocontian basin se france which presents lower aptian expanded successions characterized by major lithological changes is particularly suitable to determine palaeoenvironmental changes occurring across the oae 1a a multidisciplinary study sedimentology caco3 toc carbon and oxygen stable isotopes micropalaeontology cyclostratigraphy was carried out in the notre dame de rosans section in order to establish a detailed chronological framework of these changes the oae 1a corresponds to carbon isotope segments c3 c6 and it lasted for 1 2 myr a first drop in the carbonate production occurs 500 kyr before the oae 1a upper part of the carbon isotope segment c2 and could result from both onset of urgonian carbonate platform demise and associated reducing export of platform derived sediments into the basin and nannoconid crisis a second drastic drop crash in the carbonate production is recorded within the lower part of the oae 1a latter part of segment c3 to c5 and is explained by a strong dissolution this study then shows that the onset of the major carbonate crisis that occurs before the oae 1a could be due to both rise in sea level and in marine surface water fertility whereas its acme that occurs within the oae 1a could be related to co2 induced ocean acidification black shales of the niveau goguel occur in the upper part of the oae 1a and represent the lower part of segment c6 surface waters primary producers are principally represented by cyanobacteria whereas nannofossil primary productivity is reduced and deep water anoxia prevailed during the deposition of the niveau goguel the last 300 kyr of the oae 1a are characterized by a partial recovery of both nannofossil primary productivity and pelagic carbonate production which sharply increase just after the end of the event this study also shows that organic rich layers associated to the oae 1a are diachronous in the tethyan realm

carbon isotope composition of lower cretaceous fossil wood ocean atmosphere chemistry and relation to sea level change the carbon isotope composition of fossil wood fragments collected through a biostratigraphically well constructed aptian lower cretaceous shallow marine siliciclastic succession on the isle of wight southern britain shows distinct variations with time the results indicate that the stratigraphic signature of delta sup 13 c sub wood through the aptian was influenced primarily by fluctuations in the isotopic composition of co sub 2 in the global ocean atmosphere system as registered in marine carbonates elsewhere and was not governed by local paleoenvironmental and or paleoecological factors negative and positive excursions in delta sup 13 c sub wood through the lower aptian occur in phase with inferred transgressions and regressions respectively a pattern that contrasts with that observed in many previous studies for different time intervals the relationship between delta sup 13 c variations and relative sea level change is tentatively interpreted as a response to various climatic and eustatic factors relating to rapid sea floor spreading thermal uplift of ocean floor emplacement of plateaus volcanic co sub 2 emissions weathering and sedimentary rate

solitary waves perturbed by a broad sill part 1 propagation across the sill evolution of a solitary wave travelling along a submerged sill is studied the disturbance from the sill creates a phase lag along the wave crest between the ambient water depth and the shallower depth over the sill this phase lag causes wave diffraction between the different parts of the wave which induces radiating waves off the edge of the sill the radiating waves act as an outlet for wave energy resulting in significant and continual amplitude reduction of the solitary wave findings from laboratory experiments are confirmed numerically by simulating a much longer propagation distance with different sill breadths when the sill breadth is narrow the solitary wave slowly attenuates by wave radiation maintaining a quasi steady wave pattern this is not the case for a broader sill the resulting phase lag on the sill continually changes the wave pattern and the attenuation rate is substantially greater than the rate for the case of the narrow sill the significant energy radiation together with the continual change in the wave formation eventually leads to the complete annihilation of the solitary wave in a wave tank we also report a wave breaking process along the sill observed in laboratory experiments this breaking is induced when the wave amplitude on the sill is smaller than the maximum amplitude of a solitary wave in a uniform depth also found is the wake like formation of gravity capillary waves behind the breaking crest forming on the sill other features associated with the breaking are presented

the runup of solitary waves this is a study of the runup of solitary waves on plane beaches an approximate theory is presented for non breaking waves and an asymptotic result is derived for the maximum runup of solitary waves a series of laboratory experiments is described to support the theory it is shown that the linear theory predicts the maximum runup satisfactorily and that the nonlinear theory describes the climb of solitary waves equally well different runup regimes are found to exist for the runup of breaking and non breaking waves a breaking criterion is derived for determining whether a solitary wave will break as it climbs up a sloping beach and a different criterion is shown to apply for determining whether a wave will break during rundown these results are used to explain some of the existing empirical runup relationships

coseismic gravity changes of the 2011 tohoku oki earthquake from satellite gravimetry 1 the massive tohoku oki earthquake of a moment magnitude mw of 9 0 occurred on 11 march 2011 off the pacific coast of the northeastern japan the mass redistribution in and around the focal region associated with this earthquake was studied using the gravity changes detected by gravity recovery and climate experiment grace satellite after the 2004 sumatra andaman and the 2010 central chile maule earthquakes the present study presents the third case of clear detection of coseismic gravity changes by grace the observed gravity changes were dominated by decrease over the back arc region of 7 gal or less this reflects to a large extent coseismic crustal dilatation of the landward plate they agree well with the changes calculated with the green s function for the realistic earth using fault parameters inferred from coseismic crustal movements the spatial patterns of the gravity changes of these earthquakes are very similar because they are all shallow angle reverse faulting at convergent plate boundaries we found linear relationship between gravity decreases and seismic moments

on the evolution and run up of breaking solitary waves on a mild sloping beach abstract this paper presents new laboratory experiments carried out in a supertank 300 m 5 m 5 2 m of breaking solitary waves evolution on a 1 60 plane beach the measured data are employed to re examine existing formulae that include breaking criterion amplitude evolution and run up height the properties of shoreline motion underwater particle velocity and scale effect on run up height are briefly discussed based on our analyses it is evidently found that there exist five zones during a wave amplitude evolution course on the present mild slope a simple formula which is capable of predicting maximum run up height for a breaking solitary wave on a uniform beach with a wide range of beach slope 1 15 1 60 is also proposed the calculated results from the present model agree favorably with available laboratory data indicating that our method is compatible with other predictive models

displacement above the hypocenter of the 2011 tohoku oki earthquake the moment magnitude m w 9 0 2011 tohoku oki mega thrust earthquake occurred off the coast of northeastern japan combining global positioning system gps and acoustic data we detected very large sea floor movements associated with this event directly above the focal region an area with more than 20 meters of horizontal displacement that is four times larger than those detected on land stretches several tens of kilometers long along the trench the largest amount reaches about 24 meters toward east southeast just above the hypocenter furthermore nearly 3 meters of vertical uplift occurred contrary to observed terrestrial subsidence

temporal variation of intermediate depth earthquakes around the time of the m9 0 tohoku oki earthquake author s delbridge bg kita s uchida n johnson cw matsuzawa t burgmann r abstract 2017 american geophysical union all rights reserved the temporal evolution of intermediate depth seismicity before and after the 2011 m9 0 tohoku oki earthquake reveals interactions between plate interface slip and deformation in the subducting slab we investigate seismicity rate changes in the upper and lower planes of the double seismic zone beneath northeast japan using both a statistic approach and a temporal epidemic type aftershock sequence model we do not observe an anomalous precursory increase in intermediate depth earthquake activity preceding the mainshock however following the mainshock we observe a rate increase for the intermediate depth earthquakes in the upper plane the average ratio of upper plane to lower plane activity and the mean deep aseismic slip rate both increased by factor of 2 an increase of downdip compression in the slab resulting from coseismic and postseismic deformation enhanced seismicity in the upper plane which is dominated by events accommodating downdip shortening from plate unbending

the valanginian carbon isotope event a first episode of greenhouse climate conditions during the cretaceous lower cretaceous pelagic carbonates outcropping along the southern alps of northern italy provide a record of tethyan palaeoceanography as well as of low frequency fluctuations in the global carbon cycle the carbonate c isotope stratigraphy established at five selected localities in the southern alps allows an accurate picture to be drawn of the duration and amplitude of the valanginian c isotope event 13c values near 1 25 1 50 determined in berriasian and lower valanginian sediments are replaced by more pdsitive 13c values near 3 in the late valanginian the carbonate c isotope excursion ends in the early hauterivian with values fluctuating between 1 5 and 2 the carbonate c isotope excursion is accompanied by a positive excursion in the total organic carbon c isotope curve the valanginian c isotope excursion identified in tethyan sediments correlates with a c isotope excursion recorded in the western north atlantic in the gulf of mexico and in the central pacific dsdp sites 534 391 535 and 167 by analogy with the aptian stage also marked by a significant positive c isotope excursion the time of positive 13c values is regarded as a time of accelerated carbon cycling coupled with increased burial rates of organic carbon and detrital material in oceanic sediments a warm and humid climate possiblycoupled with a high atmospheric co2 content and a high global sea level may have triggered the acceleration of the global carbon cycling in this case the valanginian c isotope event would reflect a first episode of greenhouse earth conditions during the cretaceous

transient cooling episodes during cretaceous oceanic anoxic events with special reference to oae 1a early aptian the two major oceanic anoxic events of the cretaceous those of the early aptian oae 1a and the cenomanian turonian boundary oae 2 registered some of the highest temperatures reconstructed for the cretaceous period and are thought to be related to the input of volcanically derived carbon dioxide from one or more large igneous provinces widely distributed deposition of marine organic matter the hallmark of oaes and intensified silicate weathering in response to a globally accelerated hydrological cycle and or reaction of seawater with freshly extruded basalt are both potential mechanisms whereby the content of atmospheric carbon dioxide could have been drawn down to promote cooling on the assumption that this potential effect was not offset by increased addition of this volcanically derived greenhouse gas reduction in the supply of such carbon dioxide with deposition of organic matter and silicate weathering continuing at the same rate could also have produced cooling a transient fall in temperature and increase in marine dissolved oxygen levels is well documented for oae 2 in the form of the so called plenus cold event or benthic oxic event associated with southward invasion of certain boreal faunas and an increase in many redox sensitive and or chalcophilic elements in seawater caused by temporary loss of anoxic euxinic sinks as basalt seawater interaction continued apace high resolution studies of oae 1a show at least three cooling episodes of probable global distribution one of which recorded in the stratigraphy of the so called c4 segment is documented at high enough resolution to show correlation with an increase in carbon isotope values that was probably due to a rise in the quantities of organic matter being buried globally with consequent potential drawdown of atmospheric co2 and or reduction in volcanic input of this greenhouse gas both calcium and lithium isotope records suggest an increase in silicate weathering over the oae 1a interval but current relatively low resolution records cannot at present be tied to any one cooling episode although the lowest li isotope values do derive from the c4 segment evidence for reoxygenation of the ocean during the transient cooling episodes of oae 1a is meagre due to the lack of suitable sedimentary archives although a negative sulfur isotope excursion in a pacific shallow water carbonate section which can be interpreted as due to oxidation of pyrite and or sulfur rich organic matter in the global ocean suggests that this phenomenon may also have been a feature of the c4 segment further work is required to elucidate the similarities and differences between oae 2 and oae 1a but both phenomena are demonstrably global in reach and represent major disturbances to the carbon cycle with attendant effects on marine temperatures this article is part of a discussion meeting issue hyperthermals rapid and extreme global warming in our geological past

wave transformation and swash oscillation on gentle and steep slopes the numerical model developed previously for coastal structures is slightly modified and applied to predict the wave transformation in the surf and swash zones on gentle slopes as well as the wave reflection and swash oscillation on relatively steep beaches the numerical model is one dimensional in the cross shore direction and is based on the finite amplitude shallow water equations including the effect of bottom friction which are solved in the time domain for the incident wave train specified as input at the seaward boundary of the computation located outside the breakpoint the slight modification is related to the effect of the time averaged current on the seaward boundary condition and improves the agreement between the computed and measured mean water levels on gentle slopes the modified numerical model is compared with available small scale test data for monochromatic waves spilling on gentle slopes as well as for monochromatic waves plunging and surging on a relatively steep slope additional comparisons are made with small scale tests conducted using transient monochromatic and grouped waves on a 1 8 smooth slope with and without an idealized nearshore bar at the toe of the 1 8 slope as a whole the numerical model is shown to be capable of predicting both time varying and time averaged hydrodynamic quantities in the surf and swash zones on gentle as well as steep slopes

episodic slow slip events in the japan subduction zone before the 2011 tohoku oki earthquake abstract we describe two transient slow slip events that occurred before the 2011 tohoku oki earthquake the first transient crustal deformation which occurred over a period of a week in november 2008 was recorded simultaneously using ocean bottom pressure gauges and an on shore volumetric strainmeter this deformation has been interpreted as being an m6 8 episodic slow slip event the second had a duration exceeding 1 month and was observed in february 2011 just before the 2011 tohoku oki earthquake the moment magnitude of this event reached 7 0 the two events preceded interplate earthquakes of magnitudes m6 1 december 2008 and m7 3 march 9 2011 respectively the latter is the largest foreshock of the 2011 tohoku oki earthquake our findings indicate that these slow slip events induced increases in shear stress which in turn triggered the interplate earthquakes the slow slip event source area on the fault is also located within the downdip portion of the huge coseismic slip area of the 2011 earthquake this demonstrates episodic slow slip and seismic behavior occurring on the same portions of the megathrust fault suggesting that the faults undergo slip in slow slip events can also rupture seismically

nannofossils and superplumes the early aptian nannoconid crisis a group of calcareous nannoplankton named nannoconids experienced a crisis in the early aptian and recovered only later in the late aptian after a period of virtual absence although no extinctions occurred the widespread nature of the nannoconid crisis suggests a global causal factor this crisis is recorded within the chiastozygus litterarius nannofossil and globigerinelloides blowi planktonic foraminiferal zones postdates magnetic chronozone m0 by approximately 300 kyr and precedes the oceanic anoxic subevent 1a and associated 13c anomaly by some 40 100 kyr selective dissolution and anoxia cannot explain the crisis because nannoconids are dissolution resistant forms and their crisis clearly precedes the deposition of anoxic sediments at least 1 m y prior to the nannoconid crisis the onset of a nannoplankton speciation event may be the response of nannofloras to a major rise in relative sea level the nannoconid crisis seems to be synchronous with the early aptian volcanic eruptions in the pacific ocean hence calcareous nannoplankton were severely affected by the superplume volcanic episode the coccolithophorid bloom nannoconid crisis was possibly induced by the excessive co2 levels in the atmosphere and or caused by changes in nutrient content of oceanic surface waters fertility was enhanced by rapid turnover of nutrients due to the abnormal volcanic activity and accelerated transfer of nutrients from the continents into the oceans under warm and humid conditions of the mid cretaceous greenhouse climate the nannoconid crisis may represent a competition between phytoplankton groups for nutrients or more likely competition between different calcareous nannoplankton the biologic affinity and mode of life of nannoconus are unknown because there is no modern analog of this genus however comparison of lower cretaceous nannofossil assemblages with modern nannoplankton cummunities suggests that nannoconids like extant florisphaera profunda possibly inhabited the lower photic zone concentrations of nutrients in the upper euphotic zone may have triggered blooms of coccolithophorids and nannoconid depletion this model implies that the nannoconid crisis is the result of an abrupt major change in the structure of surface waters caused directly or indirectly by the superplume the adjustments of the biosphere to the new paleoceanographic and climatic conditions required some 40 100 kyr before changing into abnormally high primary productivity and deposition of organic carbon rich sediments with dinoflagellates outcompeting nannoplankton