trace fossils biology and taphonomy 1990 special topics in palaeontology 3 280 pp e17 95 pbk e40 00 hbk unwin hyman london isbn 004445 6867 pbk 3035 hbk

effects of source faulting and fringing reefs on the 2009 south pacific tsunami inundation in southeast upolu samoa the subduction zone along the northern tonga trench has the highest plate convergence rate in the world but limited records of its seismic and tsunamigenic activities in 2009 a tsunami generated

oceanic propagation of a potential tsunami from the la palma island 1 the likelihood of a large scale tsunami from the la palma island is considered small by most nevertheless the potential catastrophic consequences call for attention here we report on numerical simulations of a tsunami that might result from the extreme case of a flank collapse of the cumbre vieja volcano at the la palma island done by combining a multimaterial model for the wave generation with boussinesq models for the far field propagation our simulations show that the slide speed is close to critical effectively generating an initial wave of several hundred meters height our main focus is the wave propagation which is genuinely dispersive in the far field propagation becomes increasingly complex due to the combined effects of dispersion refraction and interference in the direction of propagation constructive interference of the trailing waves are found to decrease the decay of the maximum amplitude with distance compared to classical asymptotic theory at transatlantic distances thus the commonly used hydrostatic models fail to describe the propagation consequences of the la palma scenario would be largest at the canary islands but our findings also suggests that the whole central atlantic would face grave consequences however the largest surface elevations are smaller than the most pessimistic reports found in literature we also find undular bores towards the shorelines of america

evaluation of the relationship between coral damage and tsunami dynamics case study 2009 samoa tsunami on september 29 2009 an mw 8 1 earthquake at 17 48 utc in tonga trench generated a tsunami that caused heavy damage across samoa american samoa and tonga islands tutuila island which is located 250 km from the earthquake epicenter experienced tsunami flooding and strong currents on the north and east coasts causing 34 fatalities out of 192 total deaths from this tsunami and widespread structural and ecological damage the surrounding coral reefs also suffered heavy damage the damage was formally evaluated based on detailed surveys before and immediately after the tsunami this setting thus provides a unique opportunity to evaluate the relationship between tsunami dynamics and coral damage in this study estimates of the maximum wave amplitudes and coastal inundation of the tsunami are obtained with the most model titov and synolakis j waterway port coast ocean eng pp 171 1998 titov and gonzalez noaa tech memo erl pmel 112 11 1997 which is now the operational tsunami forecast tool used by the national oceanic and atmospheric administration noaa the earthquake source function was constrained using the real time deep ocean tsunami data from three dart deep ocean assessment and reporting for tsunamis systems in the far field and by tide gauge observations in the near field we compare the simulated run up with observations to evaluate the simulation performance we present an overall synthesis of the tide gauge data survey results of the run up inundation measurements and the datasets of coral damage around the island these data are used to assess the overall accuracy of the model run up prediction for tutuila and to evaluate the model accuracy over the coral reef environment during the tsunami event our primary findings are that 1 most simulated run up correlates well with observed run up for this event r 0 8 it tends to underestimated amplitudes over coral reef environment around tutuila for 15 of 31 villages run up is underestimated by more than 10 in only 5 was run up overestimated by more than 10 and 2 the locations where the model underestimates run up also tend to have experienced heavy or very heavy coral damage 8 of the 15 villages whereas well estimated run up locations characteristically experience low or very low damage 7 of 11 villages these findings imply that a numerical model may overestimate the energy loss of the tsunami waves during their interaction with the coral reef we plan future studies to quantify this energy loss and to explore what improvements can be made in simulations of tsunami run up when simulating coastal environments with fringing coral reefs

tsunami evolution and run up in a large scale experimental facility abstract in this paper we study the propagation and run up of long tsunami like waves in the 300 m long large wave flume gwk hannover germany and analyze the feasibility of experiments on tsunami run up in large facilities this paper is the continuation of our previous paper schimmels et al 2015 companion paper the propagation of long period waves over large distances for different shapes is studied experimentally and numerically fully nonlinear potential flow theory has been used to model these cases numerically along with korteweg de vries simulations the theoretical explanation of the observed effects has been discussed the run up characteristics of the studied waves with respect to their shape and beach slope were also investigated further a downscaled real tsunami time series is also reproduced experimentally and studied with regard to its possible run up

convection scaling and subduction on earth and super earths super earths are the smallest class of discovered extra solar planets owing to their relatively small mass some might resemble earth and perhaps be habitable because of the connection to habitability through thermal evolution we investigate the tectonic regime of massive terrestrial planets two independent studies o neill c lenardic a oct 2007 geological consequences of super sized earths grl 34 l19204 valencia d o connell r j sasselov d d nov 2007a inevitability of plate tectonics on super earths apjl 670 l45 l48 have reached opposing conclusions about the likelihood of plate tectonics here we offer possible reasons for the discordant findings and address three key aspects of sustaining plate tectonics deformation on faults negative buoyancy and energy dissipation during subduction we show that in general the ratio of driving force to plate resistance increases with planetary mass this is a consequence of increasing convective stresses thinning plates and similar plate structure we conclude that even though the strength of dry and wet of faults increases for massive terrestrial planets the convective stress increases even more allowing deformation to take place also despite shorter timescales for plate cooling rocky super earths achieve negative buoyancy at subduction zones finally by investigating the effects of energy dissipation during subduction we find that massive terrestrial planets dissipate less energy during subduction and hence provide a positive feedback to sustain active lid tectonics in conclusion rocky super earths have more favorable conditions than earth for the subduction of plates and hence for sustaining plate tectonics

complex decapod burrows and ecological relationships in modern and pleistocene intertidal carbonate environments san salvador island bahamas abstract burrowing by thalassinidean shrimp in modern tropical shallow subtidal to intertidal carbonate environments is widespread and a powerful agent of bioturbation particularly within sandy substrates deep and intense burrowing by callianassids commonly occurs along the intertidal margins of hypersaline lagoons throughout the bahamas such as pigeon creek on san salvador island where the sediments of extensive sand flats are thoroughly bioturbated by glypturus acanthochirus in addition to dominating the deep tier infauna g acanthochirus is a true ecosystem engineer and its prodigious burrowing activity results in a highly mounded topography on sand flats individual sediment cones commonly coalesce with time to form large composite mounds with surfaces stabilized by the development of microbial mats this unique biogenetically produced topography sets the stage for colonization by shallow tier burrowers particularly the upogebiid shrimp upogebia vasquezi and several species of fiddler crabs burrow systems of u vasquezi are distinctive and complex they typically consist of a pair of u shaped burrows in close proximity or criss crossing with knobs or short tunnels at their bases the entire u burrow pair is lined by a thick externally pelleted wall inside burrow diameters range from 0 2 to 1 cm and burrow depths are 10 15 cm in contrast to the much deeper callianassid burrows these complex upogebiid burrows also occur as trace fossils in late pleistocene lagoon margin facies of the grotto beach formation on san salvador initially reported as fragmentary burrow fills whole burrow systems virtually identical to the modern upogebiid burrows recently have been found at several localities these fossil burrows are most abundant in beds lying immediately below a terra rossa paleosol that marks the late pleistocene holocene stratigraphic boundary and the beds likely were deposited with sea level stillstand and regression associated with the onset of wisconsinan glaciation with their high potential for preservation these complex upogebiid trace fossils may prove useful as both paleoenvironmental and sea level position indicators in the study of quaternary carbonate sequences throughout the bahamas and other geologically similar regions

palaeoenvironmental and functional interpretation of rhizocorallium jenense spinosus ichnosubsp nov from the lower jurassic of asturias northern spain abstract the new ichnosubspecies rhizocorallium jenense spinosus from the late sinemurian early jurassic of asturias northern spain is described this ichnotaxon occurs in three outcrops el puntal punta rodiles and punta la llastra near the villaviciosa estuary belonging to the buerres member of the rodiles formation rhizocorallium jenense spinosus is similar in shape and size to the ichnospecies rhizocorallium jenense herein ichnosubspecies r jenense jenense in comprising short and more or less straight u shaped spreite burrows commonly obliquely oriented with respect to the bedding plane but is characterized by the presence of spine shaped protuberances on the outer margin of the arm number of observed spine shaped protuberances per specimen is variable being commonly 2 4 protuberances form obtuse equilateral or acute triangles the apical end of the spine shaped protuberance varies from pointed to rounded the specimens were emplaced in soft or slightly stiffer substrates to firmgrounds recurrent distribution of the spine shaped protuberances reveals a well programmed behavioural pattern of the tracemaker previously unknown in rhizocorallium several strategies are envisaged a a cache strategy implying that the tracemaker collected organic matter during favourable times and subsequently stored material in the spine shaped protuberances for resource poorer times b a farming strategy the spine shaped protuberances being used for concentration of micro organisms bacteria fungi and c a brooding strategy of the tracemaker revealing a relationship between brood care and oxygen provision with the location of the spine shaped protuberances on the external margin of the arms related to a better water circulation

nusselt rayleigh number scaling for spherical shell earth mantle simulation up to a rayleigh number of 10 9 abstract an investigation of the power law relationship between nusselt number nu and rayleigh number ra for earth s convecting mantle is presented the nu ra relationship was calculated from the results of a model with three dimensional spherical geometry and free slip boundary conditions both basally and internally heated convection has been examined for nu ra a ra was found to be 0 294 0 004 for basally heated systems which is lower than the value of 1 3 suggested by conventional boundary layer theory the exponent 0 337 0 009 for internally heated systems when the internally heated ra is converted to a basally heated equivalent for comparison the influence of the method used to calculate was also considered with particular attention paid to high ra as an example of the significance of 0 29 rather than 1 3 a ra of 1 0 9 results in a surface heat flux which is 32 lower within the range of ra used in this study there is no evidence that changes at high ra therefore that mechanism cannot be used to moderate mantle temperature when projecting back to early earth conditions the differing planform of basally and internally heated models was shown to result in different scaling relationships between root mean square surface velocity and ra for the two modes of heating in particular a much lower surface velocity for internally heated cases relative to equivalent ra basally heated cases

metal silicate fractionation in the growing earth energy source for the terrestrial magma ocean based on the homogeneous accretion model of planets thermal evolution of the growing earth has been studied after the surface of the growing earth starts melting owing to the blanketing effect of the primordial atmosphere gravitational differentiation between metallic and silicate materials takes place in its upper region the differentiation would give rise to a large amount of gravitational energy release as well as layered structure inside the proto earth a part of released energy would be transported outward by convection considering the effects of gravitational fractionation and convection we have pursued numerically the evolution of the growing earth our results show that gravitational differentiation can supply energy large enough to keep the whole silicate layer in the molten state and that half of the released energy is conveyed outward by convective heat transport in the growing stage the temperature distribution in the silicate layer always lies between liquidus and solidus temperatures except in an uppermost thin zone the thermal structure obtained favors a notion of the primordial magma ocean and of chemical differentiation of mantle the structure of the growing earth which is composed of the central protocore the metallic layer and the silicate layer magma ocean would become gravitationally unstable and overturn to form a metallic core energy released by this overturn would not affect the structure of the upper magma ocean too much but undifferentiated primordial materials which come from the protocore would add to mantle materials through the overturn and this would help explain the isotopic mantle heterogeneity presently observed

multiple branching rupture of the 2009 tonga samoa earthquake several source models have been proposed to explain the enigmatic 2009 tonga samoa earthquake the long period data require a composite source model and can be fit with a normal faulting subevent followed by one or more reverse faulting subevents the short period data in contrast indicate a more compact rupture pattern around the epicenter the lack of a unified source model reflects the complexity of the event we analyze the spatiotemporal evolution of this earthquake with p wave back projection from globally distributed stations in different frequency bands low frequency 0 05 0 2 hz high frequency 0 2 2 hz and a multiple moment tensor inversion the rupture propagation revealed by back projection exhibits frequency dependent behavior with two branches of high frequency enriched bilateral rupture around the epicenter and a high frequency deficient rupture branch at the subduction interface a composite source model with one mw 8 0 normal faulting earthquake east of the trench axis seaward followed by one mw 8 1 reverse faulting earthquake along the subduction interface west of the trench axis landward can explain the very long period data 200 500 s combined with high resolution swath bathymetry data the back projection images show that the azimuth of rupture branches east of the trench axis were controlled by the geometry of bending related faults on the pacific plate and that the rupture branch west of the trench axis may correlate with the along strike fore arc segmentation the rupture along the subduction interface was triggered by the seaward rupture and a partially subducted normal fault may have played a key role in facilitating the triggering the apparent normal reverse faulting interactions pose a higher seismic risk to this region than their individual strands at the northernmost corner of the tonga subduction zone

rheology of the upper mantle a synthesis rheological properties of the upper mantle of the earth play an important role in the dynamics of the lithosphere and asthenosphere however such fundamental issues as the dominant mechanisms of flow have not been well resolved a synthesis of laboratory studies and geophysical and geological observations shows that transitions between diffusion and dislocation creep likely occur in the earth s upper mantle the hot and shallow upper mantle flows by dislocation creep whereas cold and shallow or deep upper mantle may flow by diffusion creep when the stress increases grain size is reduced and the upper mantle near the transition between these two regimes is weakened consequently deformation is localized and the upper mantle is decoupled mechanically near these depths

commensal worm traces and possible juvenile thalassinidean burrows associated with ophiomorpha nodosa pleistocene southern brazil abstract the pleistocene chui formation at osorio rio grande do sul brazil consists of coastal marine and eolian sands the former containing abundant and well preserved ophiomorpha nodosa burrow systems detailed ichnological study has revealed interesting features associated with them small sized ophiomorpha here assigned to a new ichnospecies o puerilis are interpreted as possible burrows of juvenile thalassinidean crustaceans probably belonging to the same species as the producers of larger o nodosa additionally helicoidal burrows with thick concentrically laminated linings are associated with the walls of o nodosa they are assigned to the new ichnospecies cylindrichnus helix and they are interpreted as dwellings of commensal annelid worms the association of these three ichnospecies constitutes a fossil example of the role of thalassinideans as ecosystem engineers able to modify their environment and to create new space and resources usable by other organisms

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

structural and tidal models of titan and inferences on cryovolcanism titan saturn s largest satellite is subject to solid body tides exerted by saturn on the timescale of its orbital period the tide induced internal redistribution of mass results in tidal stress variations which could play a major role for titan s geologic surface record we construct models of titan s interior that are consistent with the satellite s mean density polar moment of inertia factor obliquity and tidal potential love number k2 as derived from cassini observations of titan s low degree gravity field and rotational state in the presence of a global liquid reservoir the tidal gravity field is found to be consistent with a subsurface water ammonia ocean more than 180 km thick and overlain by an outer ice shell of less than 110 km thickness the model calculations suggest comparatively low ocean ammonia contents of less than 5 wt and ocean temperatures in excess of 255 k i e higher than previously thought thereby substantially increasing titan s potential for habitable locations the calculated diurnal tidal stresses at titan s surface amount to 20 kpa almost comparable to those expected at enceladus and europa tidal shear stresses are concentrated in the polar areas while tensile stresses predominate in the near equatorial midlatitude areas of the sub and anti saturnian hemispheres the characteristic pattern of maximum diurnal tidal stresses is largely compliant with the distribution of active regions such as cryovolcanic candidate areas the latter could be important for titan s habitability since those may provide possible pathways for liquid water ammonia outbursts on the surface and the release of methane in the satellite s atmosphere

development testing and applications of site specific tsunami inundation models for real time forecasting 1 the study describes the development testing and applications of site specific tsunami inundation models forecast models for use in noaa s tsunami forecast and warning system the model development process includes sensitivity studies of tsunami wave characteristics in the nearshore and inundation for a range of model grid setups resolutions and parameters to demonstrate the process four forecast models in hawaii at hilo kahului honolulu and nawiliwili are described the models were validated with fourteen historical tsunamis and compared with numerical results from reference inundation models of higher resolution the accuracy of the modeled maximum wave height is greater than 80 when the observation is greater than 0 5 m when the observation is below 0 5 m the error is less than 0 3 m the error of the modeled arrival time of the first peak is within 3 of the travel time the developed forecast models were further applied to hazard assessment from simulated magnitude 7 5 8 2 8 7 and 9 3 tsunamis based on subduction zone earthquakes in the pacific the tsunami hazard assessment study indicates that use of a seismic magnitude alone for a tsunami source assessment is inadequate to achieve such accuracy for tsunami amplitude forecasts the forecast models apply local bathymetric and topographic information and utilize dynamic boundary conditions from the tsunami source function database to provide site and event specific coastal predictions only by combining a deep ocean assessment and reporting of tsunami constrained tsunami magnitude with site specific high resolution models can the forecasts completely cover the evolution of earthquake generated tsunami waves generation deep ocean propagation and coastal inundation wavelet analysis of the tsunami waves suggests the coastal tsunami frequency responses at different sites are dominated by the local bathymetry yet they can be partially related to the locations of the tsunami sources the study also demonstrates the nonlinearity between offshore and nearshore maximum wave amplitudes

the 2009 samoa tonga great earthquake triggered doublet great earthquakes having seismic magnitudes of at least 8 usually involve abrupt sliding of rock masses at a boundary between tectonic plates such interplate ruptures produce dynamic and static stress changes that can activate nearby intraplate aftershocks as is commonly observed in the trench slope region seaward of a great subduction zone thrust event1 the earthquake sequence addressed here involves a rare instance in which a great trench slope intraplate earthquake triggered extensive interplate faulting reversing the typical pattern and broadly expanding the seismic and tsunami hazard on 29 september 2009 within two minutes of the initiation of a normal faulting event with moment magnitude 8 1 in the outer trench slope at the northern end of the tonga subduction zone two major interplate underthrusting subevents both with moment magnitude 7 8 with total moment equal to a second great earthquake of moment magnitude 8 0 ruptured the nearby subduction zone megathrust the collective faulting produced tsunami waves with localized regions of about 12 metres run up that claimed 192 lives in samoa american samoa and tonga overlap of the seismic signals obscured the fact that distinct faults separated by more than 50 km had ruptured with different geometries with the triggered thrust faulting only being revealed by detailed seismic wave analyses extensive interplate and intraplate aftershock activity was activated over a large region of the northern tonga subduction zone

layered convection induced by phase transitions we report a systematic study on the conditions under which an endothermic phase transition can enforce layered convection two dimensional numerical calculations of convection in a domain containing a divariant phase change were performed in the framework of the extended boussinesq approximation i e considering the effects of adiabatic gradient latent heat and frictional heating in the energy equation we find that the critical value of the negative clapeyron slope which must be surpassed in order to induce layered convection decreases in magnitude with increasing rayleigh number ra in the range 104 ra 2 106 near the critical clapeyron slope vacillations between double and single layer convection or strongly leaking double layer convection are possible the breakdown into layers is influenced very little by the latent heat release but depends solely on the phase boundary deflection caused by lateral temperature differences the value of the critical clapeyron slope also seems little affected by the width of the transition zone or by its depth a possible superplastic rheology within the transition zone would tend to favor layered convection scaling the model results to the 670 km discontinuity in the earth s mantle as a possible endothermic phase boundary we estimate the critical clapeyron slope to be in the range of 4 to 8 mpa k 40 to 80 bar k the possibility that the spinel perovskite periclase transition is within this range appears to be remote but certainly cannot be neglected

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

patterns and average rates of late neogene recent uplift of the betic cordillera se spain abstract the facies distribution in the sedimentary units infilling a series of neogene basins has been used to reconstruct the relief generation and uplift across the internal zone of the betic cordillera in southern spain uplift amounts and average rates can be estimated using the current elevation of the outcrops of well dated deposits indicative of ancient sea level positions coral reefs and coastal conglomerates record the initial development of emergent betic relief during the langhian continental and marginal marine deposits indicate the existence of a large island centred on the present sierra nevada sierra de los filabres chain by the end of the middle miocene the precursor of the sierra nevada sierra de los filabres chain originally part of this large island remained emerged whilst the surrounding areas were re invaded by the sea during the early tortonian at the end of the tortonian the inland basins granada and guadix basins became continental while the sierras de la contraviesa sierra de gador and sierra alhamilla emerged separating the alboran basin from the alpujarra tabernas and sorbas basins which became narrow passages of the mediterranean sea in contrast the sierra cabrera emerged during the late messinian suggesting a progressive uplift from west to east of the sierras south of the sierra nevada sierra de los filabres chain during the pliocene only the low areas closest to the present day coast remained as marine basins and progressively emerged throughout this stage the highest average uplift rate recorded is 280 m ma for the sierra de gador although the average uplift rates of upper neogene coastal marine rocks since depositon have maximum values of approximately 200 m ma most of the uplift of the betic mountains took place before the early pliocene the recorded uplift of neogene rocks was highest at the margins of western sierra nevada where peaks higher than 3000 m occur the average rates of uplift were lower to the east of this major relief the main sierras and depressions in the present day landscape correspond respectively to the emergent land in which uplift was concentrated and to the marine basins that existed before the final emergence of the region the altitude of the sierras reflects the time at which they became emergent the highest mountains being the first to rise above sea level

stagnant lid convection in bottom heated thin 3 d spherical shells influence of curvature and implications for dwarf planets and icy moons because the viscosity of ice is strongly temperature dependent convection in the ice layers of icy moons and dwarf planets likely operates in the stagnant lid regime in which a rigid lid forms at the top of the fluid and reduces the heat transfer a detailed modeling of the thermal history and radial structure of icy moons and dwarf planets thus requires an accurate description of stagnant lid convection we performed numerical experiments of stagnant lid convection in 3 d spherical geometries for various ice shell curvatures f measured as the ratio between the inner and outer radii effective rayleigh number ram and viscosity contrast from our results we derived scaling laws for the average temperature of the well mixed interior m and the heat flux transported through the shell the nondimensional temperature difference across the bottom thermal boundary layer is well described by 1 m 1 23 f 1 5

near simultaneous great earthquakes at tongan megathrust and outer rise in september 2009 the tsunami that struck the samoan and northern tongan islands in september 2009 was preceded by a magnitude 8 earthquake on the outer slope of the oceanic trench where the pacific plate bends as it enters the subduction zone this was initially thought to be the sole source of the tsunami but a more complex picture is emerging two groups report the occurrence of two earthquakes a triggered doublet at nearly the same time and place what is not clear is which triggered the other beavan et al use an analysis of global positioning system station displacements and tsunami models to show that the outer rise earthquake was accompanied possibly triggered by a near simultaneous mega thrust earthquake in the adjacent tonga subduction zone lay et al analyse the available seismic data and their model suggests that the outer rise event triggered megathrust faulting either way this dual strike suggests a mechanism for the occasional large tsunamis generated at the tonga subduction zone on 29 september 2009 a tsunami devastated the samoan and northern tongan islands it is shown here that an unusual earthquake sequence preceded this tsunami a magnitude 8 earthquake in the outer rise intraplate region occurred almost simultaneously with rupture of the shallow subduction interplate interface equivalent to a magnitude 8 earthquake the findings provide information on strain release mechanisms at subduction zones and a possible mechanism for the occasional large tsunamis generated at the tonga subduction zone the earth s largest earthquakes and tsunamis are usually caused by thrust faulting earthquakes on the shallow part of the subduction interface between two tectonic plates where stored elastic energy due to convergence between the plates is rapidly released1 2 the tsunami that devastated the samoan and northern tongan islands on 29 september 2009 was preceded by a globally recorded magnitude 8 normal faulting earthquake in the outer rise region where the pacific plate bends before entering the subduction zone preliminary interpretation suggested that this earthquake was the source of the tsunami3 here we show that the outer rise earthquake was accompanied by a nearly simultaneous rupture of the shallow subduction interface equivalent to a magnitude 8 earthquake that also contributed significantly to the tsunami the subduction interface event was probably a slow earthquake with a rise time of several minutes that triggered the outer rise event several minutes later however we cannot rule out the possibility that the normal fault ruptured first and dynamically triggered the subduction interface event our evidence comes from displacements of global positioning system stations and modelling of tsunami waves recorded by ocean bottom pressure sensors with support from seismic data and tsunami field observations evidence of the subduction earthquake in global seismic data is largely hidden because of the earthquake s slow rise time or because its ground motion is disguised by that of the normal faulting event earthquake doublets where subduction interface events trigger large outer rise earthquakes have been recorded previously4 but this is the first well documented example where the two events occur so closely in time and the triggering event might be a slow earthquake as well as providing information on strain release mechanisms at subduction zones earthquakes such as this provide a possible mechanism for the occasional large tsunamis generated at the tonga subduction zone5 where slip between the plates is predominantly aseismic6

traveltime delay and initial phase reversal of distant tsunamis coupled with the self gravitating elastic earth systematic tsunami traveltime delays of up to 15 min relative to the numerically simulated long waves from the 2010 chilean and 2011 tohoku oki earthquakes were widely observed at deep ocean tsunamimeters enigmatic small negative phases appearing before the main peak were commonly found only at the trans oceanic locations the frequency dependence of the measured tsunami phase velocities shows reverse dispersions at long periods i e the tsunami speed becomes slower at periods beyond 1000 s this is consistent with the phase velocities of a tsunami mode coupled with a self gravitating elastic earth suggesting that the effects of compression and dilatation of seawater elastic tsunami loadings on a solid earth and the geopotential variations associated with the motion of mass during tsunami propagation are responsible for the traveltime delays and the initial negative phases simple 1 d tsunami propagation tests confirm that the reverse dispersion creates a small negative phase that precedes the main peak at large distances a new method to simulate tsunami waveforms on real ocean bathymetry that takes into account seawater compressibility the elasticity of the earth and geopotential perturbations has been developed by applying a phase correction to the simulated long waves the simulated waveforms in which phase corrections are applied for the dispersion effects accurately reproduce the observed waveforms including a small initial negative phase that appears at distant locations the traveltime difference between the observed and simulated waveforms has been decreased to less than 5 min and the waveform difference between them remarkably diminishes

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

real time experimental forecast of the peruvian tsunami of august 2007 for u s coastlines 1 at 23 41 utc on 15 august 2007 an offshore earthquake of magnitude 8 0 severely damaged central peru and generated a tsunami severe shaking by the earthquake collapsed buildings throughout the region and caused 514 fatalities the tsunami resulted in three casualties and a representative maximum runup height of 7 m in the near field the first real time tsunami data available came from a deep ocean tsunami detection buoy within 1 hour of tsunami generation these tsunami data were used to produce initial experimental forecasts within 2 hours of tsunami generation the far field forecasts indicated that the tsunami would not flood any of the 14 u s communities comparison with real time tide gage data showed very accurate forecasts

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

thermal convection and the convective regime diagram in super earths numerical models of bottom heated thermal convection of highly compressible fluid with strongly temperature dependent viscosity are presented to understand how the rayleigh number ra and the temperature dependence of viscosity exert control over the regimes of thermal convection in massive super earths thermodynamic properties of mantle materials are pressure dependent but other material properties including the viscosity are not a stagnant lid develops along the surface of the planet when the viscosity contrast across the mantle due to temperature dependence r exceeds 106 at high rayleigh number relevant to super earths the threshold in r which increases with increasing ra is higher than that expected for the earth from earlier boussinesq models the efficiency of convective heat transport measured by the nusselt number nu is considerably lower than that expected from boussinesq models nu depends on ra and r as nu 59 r 0 23 ra 109 0 27 when r 105 strong adiabatic compression significantly reduces the activity of hot ascending plumes especially at high r at r relevant for super earths hot ascending plumes lose their buoyancy on their way and hardly reach the surface boundary hot spot volcanism due to ascending plumes is probably suppressed on super earths the lithosphere is considerably thicker than that suggested by earlier boussinesq models and is unlikely to show a plate like behavior

thermal evolution of a growing mars 1 we developed a new numerical model which can simulate the thermal history and metal silicate separation of a growing mars in this model the thermal disturbance caused by planetesimal impacts is calculated for each impact event by taking into account the effects of shock heating crater excavation and isostatic rebound a metallic blob is assumed to form at the base of a magma pond if an impact site is heated above the melting temperature sinking of the metal blobs is traced assuming stokes velocity their coalescence during sinking is treated by a monte carlo approach a series of simulations is carried out assuming that mars is formed by the runaway growth from a swarm of planetesimals as was suggested by recent numerical simulations of the planetary accretion process our numerical results show that 1 no global magma ocean is formed during accretion 2 metal silicate separation takes place without global scale melting and 3 instead of a metallic core a metal rich layer is formed at the late stage of accretion

the conditions for plate tectonics on super earths inferences from convection models with damage abstract numerical simulations of mantle convection with a damage grainsize feedback are used to develop scaling laws for predicting conditions at which super earths would have plate tectonics in particular the numerical simulations are used to determine how large a viscosity ratio between pristine lithosphere and mantle l m can be offset by damage to allow mobile plate like convection regime diagrams of l m versus the damage number d show that the transition from stagnant lid to mobile convection occurs for higher l m as d increases a similar trend occurs for increasing rayleigh number we hypothesize a new criterion for the onset of plate tectonics on terrestrial planets that damage must reduce the viscosity of shear zones in the lithosphere to a critical value equivalent to the underlying mantle viscosity a scaling law based on this hypothesis reproduces the numerical results for the earth damage is efficient in the lithosphere and provides a viable mechanism for the operation of plate tectonics we scale our theory to super earths and map out the transition between plate like and stagnant lid convection with a planetary plate tectonic phase diagram in planet size surface temperature space both size and surface conditions are found to be important with plate tectonics being favored for larger cooler planets this gives a natural explanation for earth venus and mars and implies that plate tectonics on exoplanets should correlate with size incident solar radiation and atmospheric composition

outcrop and core integrative ichnofabric analysis of miocene sediments from lepe huelva sw spain improving depositional and paleoenvironmental interpretations abstract ichnofabric analysis was conducted in miocene sediments from lepe huelva sw spain based on integrative outcrop and core research to improve interpretations of depositional and paleoenvironmental conditions with special attention to sequence stratigraphy seven intervals were differentiated in outcrops based on stratigraphic and ichnological features consisting of two ichnofabrics ophiomorpha thalassinoides spongeliomorpha ichnofabric characterizes intervals 1 2 6 7 and 8 while palaeophycus planolites phycosiphon ichnofabric characterizes intervals 3 4 and 5 fourteen ichnofabrics were differentiated in the core mainly in view of lithological features including ferruginous material grain size mottled background ichnotaxa and bioturbation index a comparison between outcrop and core ichnofabrics through the upper 13 5 m corresponding to the uppermost tortonian lowermost messinian interval revealed certain similarities as well as some differences a continuous and relatively slow siliciclastic deposition with punctual variations in the sedimentation rate can be interpreted that associated with favorable paleoenvironmental parameters such as aerobic conditions and nutrient availability evidence that a well developed and diverse macroinvertebrate trace maker community existed at that time softgrounds are dominant but occasionally loosegrounds and even firmgrounds could develop the ichnofabric distribution shows long range patterns in outcrop and core and short range patterns exclusively in core long range patterns reflect the last phases of a transgressive system tract with a maximum flooding zone at the end and then a highstand normal regression high frequency short range repetitive patterns in ichnofabrics from core mainly between ichnofabrics 6 8 to 9 from lower to upper part of the pattern can be linked to local flooding surfaces subdividing the maximum flooding zone into parasequences our results reveals the usefulness of the integrative ichnofabric analysis including outcrop and core materials in sedimentary basin analysis assessing paleoenvironmental conditions and improving sequence stratigraphy characterization

thermal and chemical evolution of the terrestrial magma ocean abstract the earth is likely to have experienced a magma ocean stage during accretion thermal and chemical evolution of magma ocean is investigated based on a one dimensional two phase flow heat and mass transfer model differentiation at lower mantle pressure depends on the type of magma ocean and surrounding atmosphere if the magma ocean is formed by the blanketing effect of a solar type proto atmosphere extensive differentiation proceeds at lower mantle pressure if the magma ocean is formed by the blanketing effect of an impact induced steam atmosphere no differentiation at lower mantle pressure is likely if a very deep magma ocean is formed by a giant impact whether differentiation proceeds at lower mantle pressure or not depends on grain size viscosity of melt and or properties of a transient atmosphere on the contrary chemical differentiation likely proceeds at upper mantle pressure irrespective of magma ocean type a shallow magma ocean can remain for 100 200 my without any heating processes

lepeichnus giberti igen nov isp nov from the upper miocene of lepe huelva sw spain evidence for its origin and development with proposal of a new concept ichnogeny abstract a new ichnotaxon lepeichnus giberti igen nov isp nov is described from sandy silts and sands of the upper miocene tortonian messinian of the guadalquivir basin lepe huelva sw spain it is a complex bioturbation structure consisting of two vertical shafts interconnected by a horizontal c shaped gallery which in turn exhibits a hook shaped branch l giberti is interpreted as probably produced by a crustacean that could have combined dwelling deposit feeding and farming strategies in a shallow marine environment its architectural similarities with modern upogebiid burrows suggest the record of a new burrowing behavior not yet known today for this group of mud shrimps the large number of studied specimens and their exceptional degree of preservation allow proposing the new concept of ichnogeny as a tool to describe the origin and development of a modern or fossil boring or burrowing trace

source models and near field impact of the 1 april 2007 solomon islands tsunami within weeks of the solomon islands earthquake of 1 april 2007 international tsunami survey teams discovered important biomarkers of crust rupture and tsunami heights along the islands coastlines deep ocean tsunameters recorded the tsunami waves of this event enabling a real time inversion of the tsunami source and model evaluation of near field tsunami impact the survey measurements provide valuable datasets for further confirmation of the tsunami source of the 1 april 2007 solomon earthquake these survey results also aided investigation of the correlation between sources determined by use of tsunameter records and those derived from seismometer records or crust rupture measurements in this study to assess the near field tsunami impact we developed tsunami inundation models for the solomon islands including tsunami waveforms co seismic land level changes and tsunami height distributions on individual islands compared with seismic derived tsunami sources modeling results based on the tsunameter derived tsunami sources were a good match with field survey measurements these results highlight the accuracy and efficiency of the tsunameter derived tsunami source in modeling the near field tsunami impact along a complex archipelago we show that the source models although derived by use of different methods are all suited to initiation of inundation models developed for solomon islands as these source models become available in real time or near real time they can be implemented immediately in the inundation models to provide rapid guidance on tsunami hazard assessment focused search and rescue operations and post event recovery and reconstruction

upper pleistocene trace fossils from ponta das bicudas santiago cape verde islands systematics taphonomy and palaeoenvironmetal evolution abstract bioturbation structures from ponta das bicudas in santiago island cape verde archipelagoare located in coarse grained biocalcirudite sandwiched between basaltic lavas of the upper pleistocene assomada formation four ichnospecies have been identified rhizocorallium commune irregulare rhizocorallium jenense versum nov ichnosubsp alaichnus kabuverdiensis nov ichnogen nov ichnosp and cf dactyloidites from a taphonomic point of view most trace fossil specimens are undergoing throughout intense erosion nevertheless the observations made on their taphonomy and state of preservation allowed i to reconstruct the original complete structures of the trace fossils ii to evaluate the existence and magnitude of erosional and depositional episodes and iii to quantify the reach of erosion on the seafloor sediment in this context it was possible to quantify the thickness of sediment being eroded at the final erosional episode which happened right before the second extrusion episode of volcanic pillow lava which buried all the traces previously formed the total interval of sediment eroded was estimated in ca 1 m from a palaeoenvironmental point of view in a synthesis the traces were produced in a soft to stiffground substrate composed of very coarse grained biocalcirudite with common rhodolith debris in a shallow setting 4 to10 m of depth with moderate wave energy nearby rocky basalt knobs where corals and red coralline algae crusts were growing organisms producing rhizocorallium commune irregular settled in the seafloor during a first phase of sedimentation which was followed by an erosional episode once sedimentation resumed specimens of r jenense versum nov ichnosubsp were produced and overlapped with the former ones later a new erosional event erased most of the previous traces being preserved only the basal imprint of the specimens this was followed by a rapid sedimentation episode where alaichnus kabuverdiensis nov ichnogen nov ichnosp recorded intense bioturbation activity of the bivalve panopea subsequently under low energy sedimentation a new episode of intense bioturbation of the seafloor occurred resulting in the development of abundant cf dactyloidites finally a strong erosional event probably related to the onset of the second volcanic episode cut all previous structures before being buried by the overlying well preserved pillow lava

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

coldspots and hotspots global tectonics and mantle dynamics of venus magellan radar images and altimetry data and pioneer venus gravity data of major highlands and lowlands on venus are examined with the objective of relating these tectonic and volcanic landforms to convection within venus mantle two roughly circular lowlands atalanta and lavinia planitiae are bowl shaped depressions which contain compressional tectonic features and lack hotspot related features such as coronae and shield volcanoes they are identified as surface expressions of young mantle coldspots or regions of mantle downwelling highlands can be divided into two distinct groups volcanic rises and plateau shaped highlands volcanic rises are domical circular to elongate regions characterized by volcanic construction extensional tectonism large positive gravity and geoid anomalies centered on the highlands and large apparent depths of compensation volcanic rises include beta bell atla and western eistla regiones and are identified as surface expressions of large mantle hotspots or plumes plateau shaped highlands are steep sided elevated regions that range from circular alpha regio to elongate or irregular ovda regio tellus regio in shape their surfaces are dominated by complex ridged terrain rather than the shield volcanoes and flows that dominate volcanic rises most plateau shaped highlands contain compressional structures some of which commonly lie along their margins and have small gravity and geoid anomalies and small apparent depths of compensation compared to volcanic rises plateau shaped highlands which include those mentioned above and western ishtar terra thetis regio and phoebe regio are identified as surface expressions of mantle coldspots or regions of downwelling the highland coldspot features are elevated as a consequence of crustal thickening crustal thickening is absent or minor at lowland coldspots the importance of mantle downwelling in the tectonic deformation of venus suggests that its mantle like the mantle of earth is strongly heated from within the major venusian hotspots attest to the existence of large mantle plumes carrying heat upward from the planet s core

waves and currents in hawaiian waters induced by the dispersive 2011 tohoku tsunami this study focuses on the effects of frequency dispersion on tsunami induced coastal water waves and currents exemplified by the 2011 tohoku tsunami event the investigation relies on numerical simulations we start from a tsunami source constrained through the inversion algorithm of noaa s tsunami inundation forecast system the trans pacific propagation and the hydrodynamic processes in the hawaiian islands region are simulated with a weakly dispersive boussinesq model and a shallow water model that neglects dispersion effects from these modeling results boundary conditions are derived to force the high resolution simulations in the coastal waters in the hawaiian islands region through most a tsunami simulating code based on the shallow water theory we note that the dispersion effects generally lower the amplitudes of leading waves trailing waves of short wavelengths and high amplitudes can develop in coastal waters a model neglecting dispersion effects could under predict the wave heights and current speeds at the trailing waves

the influence of mantle internal heating on lithospheric mobility implications for super earths abstract super earths a recently discovered class of exoplanets have been inferred to be of a similar rock and metal composition to the earth as a result the possibility that they are characterised by the presence of plate tectonics has been widely debated however as the super earths have higher masses than earth it is assumed that they will also have higher rayleigh numbers and non dimensional heating rates accordingly we conduct a systematic 2d study to investigate the influence of these parameters on the surface behaviour of mantle convection the main focus of our work considers the response of surface motion to the mantle s internal heating however we also include an analysis of other parameters scaling with planet mass such as viscosity in agreement with the findings of valencia and o connell 2009 and van heck and tackley 2011 we find plate like surface mobilisation for increased rayleigh numbers but increasing the internal heating leads to the formation of a strong stagnant lid because the mantle heating effects thermally activated viscosity additionally viscosity is affected by the increased pressures and temperatures of super earths in total our findings indicate that surface mobility will likely be reduced on super sized earths our numerical models show that the interior temperature of the convecting system is of vital importance in planets with a hotter interior plate tectonics is less likely