how heterogeneous coseismic slip affects regional probabilistic tsunami hazard assessment a case study in the south china sea rupture complexity typically in the form of heterogeneous slip distribution pattern significantly affects the local tsunami wave field however the effect of rupture complexity is not commonly considered in any form of tsunami hazard assessment taking rupture complexity into account significantly increases the computational load particularly in regional scaled probabilistic tsunami hazard assessments pthas that usually require a large number of simulations based on synthetic scenarios in this study we investigate how the heterogeneous slip distribution affects the regional scaled ptha by taking the south china sea scs as an example by doing this we update ptha for the scs by incorporating the best available information of seismic tsunamigenic sources along the manila megathrust we integrate a stochastic source model into a monte carlo type simulation in which a broad range of slip distribution patterns is generated for large numbers of synthetic earthquake events green s function technique is employed to efficiently calculate the nearshore tsunami wave amplitude along the scs coastlines our result suggests that for a relatively small and confined region like the scs the commonly used approach based on the uniform slip model significantly underestimates tsunami hazard not only in the near source region like west luzon as expected but also in the relative far field such as south china and central vietnam additionally our sensitivity test of the patch size effects suggests that large patch size is unable to adequately resolve the details of heterogeneous seafloor deformation and such approaches considerably underestimate the potential tsunami hazard for the scs coasts

palynology dacryoconarids and the lower eifelian middle devonian basal chotec event case studies from the prague and appalachian basins

a geosat altimeter wind speed algorithm and a method for altimeter wind speed algorithm development a geosat altimeter wind speed algorithm is derived by cross calibrating geosat and seasat altimeter estimates of the normalized radar cross section 0 and modifying an existing seasat altimeter wind speed model function to obtain a model function appropriate for geosat observations it is argued that the 0 distribution measured by an altimeter is relatively stable over a sufficiently large geographical region and a long enough time period systematic differences between 0 estimates from two altimeters can therefore be identified based on comparisons of their 0 histograms any such systematic differences can then be corrected using independent 0 estimates when this method is applied to the geosat and seasat altimeters a systematic difference between the two 0 histograms is shown to be consistent with differences between seasat altimeter and nadir seasat scatterometer estimates of 0 deduced independently by a previous study this supports the conclusions that 1 the 0 distribution is stable and 2 the seasat altimeter estimates of 0 were miscalibrated after modifying the existing seasat altimeter wind speed algorithm to account for this apparent 0 error the resulting geosat estimates of wind speed agree with high quality buoy observations to within an rms difference of less than 2 m s

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

a guide to stratigraphical procedure the continuing development of stratigraphical concepts and the application of new methods has led the stratigraphy committee of the geological society of london to present a new guide to stratigraphical procedure some of the principal types of stratigraphy are outlined and guidelines and recommendations are given on procedure practice and terminological usage

tsunamigenic potential of an incipient submarine slope failure in the northern south china sea abstract tsunamis generated by submarine slope failures have the potential to cause devastating consequences the combination of 1 dense population and infrastructure along the coastline of south china sea scs and 2 frequent slope failures occurring along the marine slopes of the scs points to the vulnerability of china and surrounding countries to submarine landslide related tsunamis a geohazard that is still poorly understood in the scs in this study the tsunamigenic potential of a possible future slope failure along the continental slope of the scs is estimated after being constrained by geophysical data interpretation and numerical modeling results suggest that a slope failure of a scale similar to past events would likely generate a catastrophic tsunami on the numerous islands scattered throughout the northern scs with maximum wave height of 21 8 m furthermore the highly populated coastlines of scs would experience widespread tsunami events with maximum wave height of 6 m and little advance warning this preliminary study suggests that tsunamis generated by submarine slope failure are a potentially significant geohazard to the coastlines of scs and should be considered during the assessment of scs geohazard

sea surface wind streaks in spaceborne synthetic aperture radar imagery wind streaks are often observed in synthetic aperture radar sar images they are used to determine the sea surface wind direction for sea surface wind field retrievals it is generally understood that visible wind streaks are caused by roll vortices in the marine atmospheric boundary layer in this study 227 x band spaceborne sar terrasar x and tandem x images acquired from the three fino platforms in the north sea and baltic sea were thoroughly analyzed for a comprehensive understanding of the manifestation of wind streaks in sar images approximately 48 0 of the 227 sar images displayed wind streaks among which 67 3 20 0 and 12 7 occurred under unstable neutral stable atmospheric conditions respectively the proportions indicate that wind streaks are more likely to be generated from thermal convection further investigations suggest that the inflection point and the wind shear may be essential for the appearance of wind streaks in sar images under stable atmospheric conditions this article is protected by copyright all rights reserved

ocean wave slope observations using radar backscatter and laser altimeters abstract combination of laser and radar aboard an aircraft is used to directly measure long gravity wave surface tilting simultaneously with nadir viewing microwave backscatter from the sea surface the presented dataset is extensive encompassing varied wind conditions over coastal and open ocean wave regimes laser derived slope statistics and ka band 36 ghz radar backscatter are detailed separately to document their respective variations versus near surface wind speed the slope statistics measured for 1 2 m show good agreement with cox and munk s oil slickened sea measurements a notable exception is elevated distribution peakedness and an observed wind dependence in this likely proxy for nonlinear wave wave interactions aircraft ka band radar data nearly mimic ku band satellite altimeter observations in their mean wind dependence the present calibrated radar data along with relevant observational and theoretical studies suggest a large 5 db bias in previous ka band results next wave

brachiopod faunas facies and biostratigraphy of the pridolian to lower eifelian succession in the rhenish massif rheinisches schiefergebirge germany

landslide tsunami hazard along the upper us east coast effects of slide deformation bottom friction and frequency dispersion numerical simulations of submarine mass failures smfs are performed along the upper us east coast to assess the effect of slide deformation on predicted tsunami hazard tsunami generation is simulated using the three dimensional non hydrostatic model nhwave for rigid slumps the geometry and law of motion are specified as bottom boundary conditions deforming slide motion is modeled using a depth integrated bottom layer of dense newtonian fluid fully coupled to the overlying fluid motion once the smfs are no longer tsunamigenic tsunami propagation simulations are performed using the boussinesq wave model funwave tvd using nested grids of increasingly fine resolution towards shore and employing a one way coupling methodology probable maximum tsunamis are simulated for currituck smf proxies sited in four areas of the shelf break slope that have enough sediment accumulation to cause large failures deforming slides have a slightly larger initial acceleration but still generate a smaller tsunami than rigid slumps due to their spreading and thinning out during motion which gradually makes them less tsunamigenic comparing the maximum envelope of surface elevations along a 5 m isobath consistent with earlier work the bathymetry of the wide shelf is found to strongly control the spatial distribution of tsunami inundation overall tsunamis caused by rigid slumps are worst case scenarios providing up to 50 more inundation than for deforming slides having a moderate level of viscosity set in the upper range of debris flows tsunamis from both types of smfs are able to cause water withdrawal to the 5 m isobath or deeper bottom friction effects are assessed by performing some of the simulations using two different manning coefficients one 50 larger than the other with increased bottom friction the largest tsunami inundations at the coast are reduced by up to 15 selected simulations are rerun by turning off dispersion in the model which leads to moderate changes in maximum surface elevations nearshore 10 to 5 changes but to more significant effects in the far field 40 to 80 changes onshore dispersion causes the appearance of short period undular bores that eventually break nearshore without significantly affecting inundation at the coast however these bores increase wave induced maximum flow velocity and impulse forces the latter by up to 40 which may affect the design of coastal structures

hydrodynamic modeling of tsunamis from the currituck landslide article i nfo article history accepted 24 september 2008 tsunami generation fromthe currituck landslide offshore northcarolina and propagation of waves towardthe u s coastline are modeled based on recent geotechnical analysis of slide movement a long and intermediate wave modeling package coulwave based on the non linear boussinesq equations are used to simulate the tsunami this model includes procedures to incorporate bottom friction wave breaking and overland flow during runup potential tsunamis generated from the currituck landslide are analyzed using four approaches 1 tsunami wave history is calculated from several different scenarios indicated by geotechnical stability and mobility analyses 2 a sensitivity analysis is conducted to determine the effects of both landslide failure duration during generation and bottom friction along the continental shelf during propagation 3 wave history is calculated over a regional area to determine the propagation of energy oblique to the slide axis and 4 a high resolution 1d model isdeveloped to accuratelymodel wavebreakingand the combined influence of nonlinearity and dispersion during nearshore propagation and runup the primary source parameter that affects tsunami severity for this case study is landslide volume with failure duration having a secondary influence bottom friction during propagation across the continental shelf has a strong influence on the attenuation of the tsunami during propagation the high resolution 1d model also indicates that the tsunami undergoes nonlinear fission prior to wave breaking generating independent short period waves wave breaking occurs approximately 40 50 km offshore where a tsunami bore is formed that persists during runup these analyses illustrate the complex nature of landslide tsunamis necessitating the use of detailed landslide stability mobility models and higher order hydrodynamic models to determine their hazard published by elsevier b v

validation and assimilation of seasat altimeter wave heights using the wam wave model the mutual consistency of the seasat global data sets of scatterometer winds and altimeter wave heights is investigated for the complete seasat period using the third generation wave model wam the wave model was driven by surface 1000 hpa wind and surface stress fields constructed by the goddard laboratory for atmospheres gla by assimilation of the scatterometer winds in an atmospheric model for the 10 day period september 7 17 the intercomparison was extended to two further scatterometer wind fields a 1000 hpa assimilated wind field from the european centre for medium range weather forecasts and a subjectively analyzed 19 5 m height surface wind field from the jet propulsion laboratory on the global average the modeled and observed wave heights agree reasonably well regional differences however can be large and sometimes exceed 40 the errors are attributed mainly to deficiencies in the forcing wind fields low wind speeds are found to be overestimated and high wind speeds underestimated by the seasat scatterometer algorithm the friction velocities of the gla model are found to be significantly underestimated in the high wind belt of the southern hemisphere the analysis demonstrates the diagnostic advantages of applying a wave model for the quality assessment of satellite wind and wave data a preliminary wave data assimilation scheme is presented in which the wave field is updated without changing the forcing wind field a considerable improvement of the computed wave field is achieved particularly in regions in which the wave energy is dominated by swell however a more general assimilation scheme including modifications of the wind field is needed to upgrade wind sea forecasts

a marine fauna from the dartmouth beds lower devonian of cornwall a brachiopod fauna is described from a marine horizon within the dartmouth beds at bull cove cornwall the fauna indicates a middle or late siegenian age and aspects of the palaeoecology are discussed the lower devonian succession of south devon and north cornwall is discussed and the terms meadfoot facies and standon facies are proposed to replace the meadfoot beds and staddon grits of the old terminology

reconstruction of storm tsunami records over the last 4000 years using transported coral blocks and lagoon sediments in the southern south china sea large transported coral blocks on reef flats and elevated sedimentation rates in atoll lagoons were demonstrated to be excellent proxies for past strong storms tsunamis in the southern south china sea here we introduce another important proxy coarse fraction contents of lagoon sediments this proxy is based on the principle that coarse fractions of enclosed lagoon sediments are usually controlled by strong sedimentary dynamics on the surrounding reef flat and thus increases in the weight percentages of coarse grained fractions of the lagoon sediments should also reflect strong storm tsunami events or increases in storminess with the size of the content peak as the proxy for the degree of storminess bearing this in mind we measured the contents of the 1 mm grain size fractions referred to as coarse fraction content in an undisturbed lagoon core precisely dated to cover the last 4000 years the decadal resolution data show a systematic variation with some peaks strongly correlated with in timing with strong storm tsunami events dated at ad 1872 15 1685 8 similar to 1680 6 1443 9 1336 9 1210 5 similar to 1201 4 and 1064 30 using wave transported coral blocks using the mean coarsefraction content 9 2 for the entire core as a reference line a total of 77 peaks were identified for the past 4000 years twenty of these peaks are higher than 23 the mean value for peaks that are correlated in age with the six strong storm events identified using independently dated coral blocks among these 23 peaks 13 occurred within the last 1000 years the concentration of contentpeaks in the last millennium could be partially due to higher deposition rates and sampling resolution over the last similar to 4000 years there appears to be a weakly increasing trend in coarse fraction contents towards present time but this trend is not obvious within the last millennium this long term variation may be related to changes in both storminess and reef lagoon morphology however the data do suggest three extremely stormy periods centring around ad similar to 1200 similar to 400 bc and similar to 1200 bc respectively overall this study demonstrates that combined use of transported coral blocks and coarse fraction contents of lagoon sediments provides an excellent means for comprehensive reconstruction of past storm tsunami activity c 2008 elsevier ltd and inqua all rights reserved

three dimensional seismic studies of deep water hazard related features on the northern slope of south china sea mass transport deposits and geological features related to fluid flow such as gas chimneys mud diapirs and volcanos pockmarks and gas hydrates are pervasive on the canyon dominated northern slope of the pearl river mouth basin of the south china sea these deposits and structures are linked to serious geohazards and are considered risk factors for seabed installations based on high resolution three dimensional seismic surveys seismic characteristics distributions and origins of these features are analyzed a distribution map is presented and geometrical parameters and spatial distribution patterns are summarized results show that various groups of the mapped features are closely tied to local or regional tectonism and sedimentary processes mass transport complexes are classified as slides near the shelf break initially deformed slumps on the flanks of canyons and highly deformed slumps on the lower slope downslope of the mouth of canyons we propose them to be preconditioned by pore pressure changes related to sea level fluctuations steep topography and fluid and fault activities gas chimneys are mainly located in the vicinity of gas reservoirs while bottom simulating reflectors are observed within the gas chimney regions suggesting gas chimneys serve as conduits for thermogenic gas mud diapirs volcanos and pockmarks are observed in small numbers and the formation of pockmarks is related to underlying gas chimneys and faults this study aims at reducing risks for deep water engineering on the northern slope of south china sea c 2016 elsevier ltd all rights reserved

a physical model of sea wave period from altimeter data a physical model for sea wave period from altimeter data is presented physical roots of the model are in recent advances of the theory of weak turbulence of wind driven waves that predicts the link of instant wave energy to instant energy flux to from waves the model operates with wave height and its spatial derivative and does not refer to normalized radar cross section 0 measured by the altimeter thus the resulting formula for wave period does not contain any empirical parameters and does not require features of particular satellite altimeter or any calibration for specific region of measurements a single case study illustrates consistency of the new approach with previously proposed empirical models in terms of estimates of wave periods and their statistical distributions the paper brings attention to the possible corruption of dynamical parameters such as wave steepness or energy fluxes to from waves when using the empirical approaches applications of the new model to the studies of sea wave dynamics are discussed

sedimentology and depositional setting of the dartmouth group bigbury bay south devon the lower devonian dartmouth group records some of the earliest stages in the evolution of the variscan basins of southwest england this thick mudstone dominated group has previously been interpreted as distal fluvial sediments deposited on a coastal mudplain the sequence at bigbury bay is made up of two large scale sedimentary cycles the base of each cycle consists of pebbly mudstones graded siltstones and sandstones massive mudstones and heterolithic sediments with sporadic phosphatic nodules these facies were deposited in substantial lakes they were modified by phases of syn sedimentary deformation which generated subaqueous debris flows and turbidites the overlying parts of the cycle making up the bulk of the succession consist of mudstone and thin sheet like sandstones these are fluvial and were probably deposited in mud dominated terminal fans each cycle represents a phase of rapid probably fault controlled subsidence followed by relative tectonic quiescence this behaviour may reflect pulses of rifting or extension in strike slip basins followed by thermal relaxation

further development of an improved altimeter wind speed algorithm a previous altimeter wind speed retrieval algorithm was developed on the basis of wind speeds in the limited range from about 4 to 14 ms 1 in this paper we use a new approach which gives a wind speed model function applicable over the range 0 to 21 ms 1 the method is based on comparing 50 km along track averages of the altimeter normalized radar cross section measurements with neighboring off nadir scatterometer wind speed measurements the scatterometer winds are constructed from 100 km binned measurements of radar cross section and are located approximately 200 km from the satellite subtrack the new model function agrees very well with earlier versions up to wind speeds of 14 ms 1 but differs significantly at higher wind speeds we discuss the relevance of these results to the geosat altimeter launched in march 1985

past and potential tsunami sources in the south china sea a brief synthesis abstract extending across some 3 5 million square km and with coastlines populated by in excess of 80 million people the south china sea scs is bordered by seven independent states understanding the risk of tsunamis in the scs is therefore an imperative especially given the new priorities for the science community following the endorsement by the un general assembly of the sendai framework for disaster risk reduction 2015 2030 our review presents a synthesis of existing literature on the current state of knowledge concerning known tsunamigenic threats but also highlights a number of other potential sources that have so far received less attention or gone largely un or under recognised an overview of the geological evolution of the scs is presented in order to appreciate how the existing structural configuration of the ocean basin is responsible for the presence of a variety of potential tsunamigenic mechanisms traditional thinking places the generation of a large magnitude earthquake at the manila trench subduction zone at the top of the spectrum for tsunami potential with several simulations already available in the literature illustrating wave characteristics resulting from the worst case rupture in addition to the manila trench and other possible earthquake sources however volcanic activity and submarine landsliding of sediment burden on continental shelves on the scs margins represent hitherto fundamentally unquantified tsunami threats although revealed nonetheless by for example the existence of the giant brunei and baiyun submarine slides furthermore in the central scs previously considered essentially devoid of tsunami sources numerous near surface carbonate platforms and coral atolls show evidence of arcuate bight like structures in their planform geometry likewise suggesting their propensity for possible tsunamigenic lateral flank collapse in the current absence of well constrained tsunami probability estimates and scenarios of wave size and propagation features for non earthquake tsunami sources future research priorities lie in two main areas these are 1 improvement of modelling for tsunamigenic submarine failures as well as for earthquakes and 2 a greater focus on geomorphic investigation to identify palaeotsunami deposits on coastlines considered likely to have been impacted in the past and where good preservation potential exists this is needed to establish the magnitude timing frequency of events on holocene timescales the last 10 000 years well beyond historical records thereby improving our capabilities for understanding and forecasting the likelihood and severity of future tsunami risk in the south china sea

fetch and duration limited nature of surface wave growth inside tropical cyclones with applications to air sea exchange and remote sensing abstractthe 2d wavenumber spectra collected by an airborne scanning radar altimeter in hurricane hunter missions are used to investigate the fetch and duration limited nature of wave growth inside hurricanes despite the much more complex wind forcing conditions the dimensionless growth curves obtained with the wind wave triplets reference wind velocity significant wave height and dominant wave period inside hurricanes except near the eye region are comparable to the reference similarity counterparts constructed with the wind wave triplets collected in field experiments conducted under ideal quasi steady fetch limited conditions in dimensionless terms the youngest waves are in the back quarter of the hurricane in the northern hemisphere the dimensionless frequency decreases systematically counterclockwise ccw and the most mature waves are in the left hand sector except for those waves near the eye region the dominant wave phase speeds are about 0 32 to 0 71 times of the local wind speed

tsunami hazard assessment for atoll islands inside the south china sea a case study of the xisha archipelago abstract the potential tsunami hazard for atoll islands inside the south china sea scs has not been investigated previously in this study we assess the tsunami hazard for the xisha archipelago using a deterministic approach the tsunami source considered in this study is hypothesized earthquakes in the manila subduction zone we employ comcot cornell multi grid coupled tsunami model for tsunami simulations different with previous deterministic assessments our study investigates the uncertainties caused by bathymetric resolution and rupture complexities here refers to rupture speed and direction variations related to fault geometry complexity comparison between results of different resolution suggests that coarser grids may over underestimate tsunami hazards around mid ocean atoll islands and this depends on the surrounding bathymetry but results of different datasets show that gebco may lead to a lower result than the multibeam data we also investigate the uncertainties caused by different rupture speed and direction which are highly affected by subducting seamounts ridge different rupture direction will shift the hardest hit locations to areas which are possibly underestimated in cases of instantaneous ruptures also the distribution of slip and location of the rupture zone can affect the local tsunami wave height significantly we suggest that near island high resolution bathymetric data and dynamic rupture process should be considered in future tsunami hazard assessment in locations with similar geological structures

propagation and amplification of tsunamis at coastal boundaries when tsunamis hit a coastal area they often cause substantial damage and loss of life at locations otherwise well protected from normal even severe wind generated waves an example of such a catastrophe took place on 12 december 1992 when an earthquake of magnitude ms 7 5 occurred in the eastern region of flores island indonesia1 2 one of the areas hardest hit by the resulting tsunamis was babi a small coastal island two villages on the island were completely destroyed even though both were located in sheltered areas where wave conditions are normally calm here we describe the results of numerical and laboratory experiments that show how unlike wind generated waves tsunamis are capable of penetrating into sheltered coastal areas without significantly losing their energy for the case of babi island the original tsunami wave was split into two with one wave propagating around each side of the island the two waves met in the sheltered region and the subsequent amplification of wave amplitude resulted in the destructive flow onto the beach

a probabilistic approach for determining submarine landslide tsunami hazard along the upper east coast of the united states abstract tsunami hazard assessment is critical for coastal communities emergency services and industry to develop regional risk and response management plans for catastrophic tsunami events such as the recent 1998 papua new guinea png and 2004 indian ocean tsunamis along the northeastern united states coastline tsunami hazard assessment is in its infancy mostly due to the lack of historical tsunami record and the uncertainty regarding the return periods of potential large scale events the latter includes large transoceanic tsunamis such as could be caused by a collapse of the cumbre vieja volcano in the canary islands or a large co seismic tsunami initiated in the puerto rican trench as well as large local tsunamis such as could be caused by a submarine mass failure smf occurring on the nearby continental slope in this region considerable geologic and some historical e g the 1929 grand bank landslide tsunami evidence suggests that the largest tsunami hazard may arise from tsunamigenic smfs triggered by moderate seismic activity the coastal impact of smf or landslide tsunamis indeed can potentially be narrowly focused and affect specific communities this research presents the development validation and results of a probabilistic geomechanical and coastal tsunami impact analysis of tsunami hazard on the upper northeast coast of the united states results are presented in terms of nearshore breaking wave height and runup caused by seismically induced tsunamigenic smf with a given return period a monte carlo approach is employed in which distributions of relevant parameters seismicity sediment properties type and location volume and dimensions of slide water depth etc are used to perform large numbers of stochastic stability analyses of submerged slopes along actual shelf transects based on standard pseudo static limit equilibrium methods the distribution of predicted slope failures along the upper u s east coast is found to match published data quite well for slopes that are deemed unstable for a specified ground acceleration with given return period the tsunami source characteristic height is found using empirical equations based on earlier numerical simulation work and corresponding breaking height and runup are estimated on the nearest coastline for a 0 2 annual probability ground acceleration for instance simulations yield a return period of tsunamigenic smfs of 3350 yr i e a 0 03 annual probability of occurrence the resulting estimate of the overall coastal hazard from 100 and 500 yr smf tsunami events is found to be quite low at most locations as compared to the typical 100 yr hurricane storm surge in the region 4 5 m specifically for the 100 yr event smf tsunami hazard is quite low with no coastal region exceeding a 1 m runup for the 500 yr event however two regions of relatively elevated hazard are found 1 near long island ny with a peak runup of 3 m and 2 near the new jersey coast with a peak runup of 4 m it should be stressed that these are only first order estimates and detailed tsunami inundation modeling is required to fully quantify tsunami runup and inundation at these sites this will be the object of more detailed studies in future work

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

the confrontation of structural styles and the evolution of a foreland basin in central sw england detailed mapping of the rocks to the north and south of plymouth reveals a sedimentary sequence deformed by a series of folds and thrusts two structural zones exist each with a different style of deformation in the lower to upper devonian rocks of the southern zone slip vectors vergence and facing of d1 folds indicate that the transport direction is to the north west an associated first phase cleavage dips to the south east the northern zone of upper devonian and lower carboniferous strata extends into central devon and east cornwall and the geometry and facing of the early folds in these rocks indicate a transport direction to the south or south east d1 folds generally verge north but are downward facing towards the south a flat lying penetrative slaty cleavage occurs in the mudrocks and also indicates southward facing generally the carboniferous rocks in this area are inverted the two structural zones confront each other at an e w trending line which passes through cargreen 8 km north of plymouth here the deformation is more intense as the cleavage common to the southern zone overprints that of the northern zone resulting in the formation of d2 folds the confrontation is interpreted as a northerly dipping backthrust produced by large scale underthrusting it is proposed that the northward advancing variscan thrust belt progressively underthrust the carboniferous foreland basin flysch deposits which became inverted and backthrust towards the south

tsunami hazard and early warning system in south china sea abstract in this paper we discuss the potential tsunami hazard in the south china sea region we focus our discussions on the characteristics of tsunamis generated from earthquakes along the manila subduction zone a procedure is presented for establishing a tsunami early warning system in the region a scenario case is used to demonstrate the feasibility of the early warning system

some giant submarine landslides do not produce large tsunamis landslides are the second most important cause of tsunamis after earthquakes and their potential for generating large tsunamis depend on the slide process among the world s largest submarine landslides is the storegga slide that generated an ocean wide catastrophic tsunami while no traces of a tsunami generated from the similar and nearby traenadjupet slide have been found previous models for such landslide tsunamis have not been able to capture the complexity of the landslide processes and are at odds with geotechnical and geomorphological data that reveal retrogressive landslide development the tsunami generation from these massive events are here modeled with new methods that incorporate complex retrogressive slide motion we show that the tsunamigenic strength is closely related to the retrogressive development and explain for the first time why similar giant landslides can produce very different tsunamis sometimes smaller than anticipated because these slide mechanisms are common for submarine landslides modeling procedures for dealing with their associated tsunamis should be revised

a statistical comparison of wind speed wave height and wave period derived from satellite altimeters and ocean buoys in the gulf of mexico region the capability of spaceborne altimeters to provide precise measurement of significant wave height and wind speed has been demonstrated repeatedly it is shown in this paper that in addition to the significant wave height and wind speed the wave period can be calculated from the semiempirical functions established from earlier wave research the calculated characteristic wave period using the altimeter derived wind speed and wave height are found to be in excellent agreement with the peak wave period and average wave period from the ocean buoy measurements in the gulf of mexico also with the long time series of collocated data set it is possible to compare altimeter output of wind and wave parameters with ocean buoy measurements taking into consideration the spatial lags between the buoy locations and the altimeter footprints and the temporal lags between the two sensor systems it is found that when the spatial lags are less than 10 km the rms difference of the significant wave height is approximately 0 1 m which is the digitization resolution of the output from both altimeter and ocean buoy for the wind speed the rms difference approaches 1 2 m s in the gulf of mexico using the empirical algorithms the wind speed agreement is significantly improved to 0 8 m s when the tilting effect on the altimeter cross section is accounted for in contrast to the spatial lags temporal lags of up to 1 hour do not appear to produce significant difference in the statistics of comparison based on this study

tsunami hazard from the subduction megathrust of the south china sea part i source characterization and the resulting tsunami abstract the subduction megathrust under the manila trench has been accumulating strain over a period of 440 years or more and could be the source for a giant earthquake of m w 9 we present a plausible earthquake rupture model constructed from seismic and geodetic data together with hydrodynamic simulations of the potential tsunami with comcot cornell multi grid coupled tsunami model results indicate that this megathrust poses a risk of devastating tsunami for the philippines southern china vietnam and other population centers bordering the south china sea

comparison of composite bragg theory and quad polarization radar backscatter from radarsat 2 with applications to wave breaking and high wind retrieval 1 depolarized de pol radar backscatter is now produced by many spaceborne satellites analysis of radarsat 2 r2 quad polarization quad pol data with collocated in situ ocean wind measurements reveals that the de pol radar backscatter does not saturate in high winds this is a significant development for radar wind sensing because wind retrieval with copolarized co pol backscatter suffers from problems of incidence and azimuth angle dependent signal saturation and dampening in high winds we present a study comparing satellite quad pol measurements with the composite surface bragg cb theory of radar backscattering from the ocean surface the co pol data are in good agreement with the cb theory de pol data are more sensitive to wind speed compared to theoretical prediction thus retrieval of high winds is more accurate using the de pol return the cubic wind speed dependence of de pol returns in high winds reflects the significant breaking wave contributions the relationship can be used to obtain wave breaking properties from space

the 2010 mw 7 8 mentawai earthquake very shallow source of a rare tsunami earthquake determined from tsunami field survey and near field gps data 1 the mw 7 8 october 2010mentawai indonesia earthquake was a tsunami earthquake a rare type of earthquake that generates a tsunami much larger than expected based on the seismicmagnitude itproducedalocallydevastatingtsunami withrunupcommonlyinexcess of 6 m we examine this event using a combination of high rate gps data from instruments located on the nearby islands and a tsunami field survey the gps displacement time series are deficient in high frequency energy and show small coseismic displacements 16 m our modeling results show that the combination of the small gps displacements and large tsunami can only be explained by high fault slip at very shallow depths far from the islands and close to the oceanic trench inelastic uplift of trench sediments likely contributed to the size of the tsunami recent results for the 2011 mw 9 0 tohoko oki earthquake have also shown shallow fault slip but the results from our study which involves a smaller earthquake provide much stronger constraints on how shallow the rupture can be with the majority of slip for the mentawai earthquake occurring at depths of 6 km this result challenges the conventional wisdom that the shallow tips of subduction megathrusts are aseismic and therefore raises important questions both about the mechanical properties of the shallow fault zone and the potential seismic and tsunami hazard of this shallow region

a giant submarine creep zone as a precursor of large scale slope instability offshore the dongsha islands south china sea a giant submarine creep zone exceeding 800 km2 on the continental slope offshore the dongsha islands south china sea is investigated using bathymetric and 3d seismic data tied to borehole information the submarine creep zone is identified as a wide area of seafloor undulations with ridges and troughs the troughs form nw and wnw trending elongated depressions separating distinct seafloor ridges which are parallel or sub parallel to the continental slope the troughs are 0 8 4 7 km long and 0 4 to 2 1 km wide the ridges have wavelengths of 1 4 km and vertical relief of 10 30 m slope strata are characterised by the presence of vertically stacked ridges and troughs at different stratigraphic depths but remaining relatively stationary in their position the interpreted ridges and troughs are associated with large scale submarine creep and the troughs can be divided into three types based on their different internal characters and formation processes the large scale listric faults trending downslope below mtd 1 and horizon t0 may be the potential glide planes for the submarine creep movement high sedimentation rates local fault activity and the frequent earthquakes recorded on the margin are considered as the main factors controlling the formation of this giant submarine creep zone our results are important to the understanding of sediment instability on continental slopes as a the interpreted submarine creep is young or even active at present and b areas of creeping may evolve into large scale slope instabilities as recorded by similar large scale events in the past

relationships between ku band radar backscatter and integrated wind and wave parameters at low incidence angles by using ten years of collocated precipitation radar and buoy data the relationships between ku band normalized radar cross section and integrated wind and wave parameters e g significant wave height wave period wave steepness and wave age at low incidence angles are analyzed for different sea states using correlation and dependence analysis the results show that the relationships are significantly different for different sea states second the potential for inverting these parameters directly from a single is investigated the results reveal that the retrieval of wind speed above 10 m u10 is most suitable for a nonpure swell sea and that the performance of significant wave height hs retrieval decreases with the ratio of swell to wind waves for wave period and wavelength a feasible inversion can only be performed for a wind wave dominated sea wave steepness a is strongly correlated with in all sea states and can even be higher than that for u10 in pure swell seas it is suggested from the present data set that real wave age may be retrieved from a swell dominated sea and therefore has a low value cutoff furthermore the extent to which u10 retrieval depends on sea state is examined by calculating the correlation coefficient between residuals and various standard wave parameters and then by determining the partial correlation coefficient between and each wave parameter controlled by u10 both results indicate that wind direction is better taken into account above 13 5 moreover an auxiliary parameter related to wave slope such as wave steepness would help to improve retrieval performance significant wave height data are of secondary use but an implementation with real wave age information might not significantly improve wind speed retrieval to improve the performance of hs and wave period retrieval auxiliary information such as wind speed wave steepness or wave age is needed finally multivariable empirical models are proposed

size distribution of submarine landslides and its implication to tsunami hazard in puerto rico 1 we have established for the first time a size frequency distribution for carbonate submarine slope failures using detailed bathymetry along the northern edge of the carbonate platform north of puerto rico we show that the cumulative distribution of slope failure volumes follows a power law distribution the power law exponent of this distribution is similar to those for rock falls on land commensurate with their interpreted failure mode the carbonate volume distribution and its associated volume area relationship are significantly different from those for clay rich debris lobes in the storegga slide norway coupling this relationship with tsunami simulations allows an estimate of the maximum tsunami runup and the maximum number of potentially damaging tsunamis from landslides to the north shore of puerto rico

the dependence of sea surface slope on atmospheric stability and swell conditions a tower mounted optical device is used to measure the two orthogonal components of the sea surface slope the results indicate that an unstable stratification at the air sea interface tends to enhance the surface roughness the presence of a long ocean swell system steers the primary direction of shortwave propagation away from wind direction and may increase or reduce the mean square slope of the sea surface

what caused the mysterious eighteenth century tsunami that struck the southwest taiwan coast several different historical records allude to a disastrous tsunami on the southwestern taiwan coast sometime between 1781 and 1782 with a reported death toll of more than 40 000 despite consistent reports from southwest taiwan no corroborative information exists for neighboring shorelines in southeast china or northwest luzon philippines and a plausible source of this tsunami has never been identified neither a large earthquake from the manila trench and active thrust faults nor a submarine volcanic eruption from the northern luzon arc can explain the very localized area affected and the physical phenomena described in the historical records comparing the results of 13 numerical models of tsunamis generated from different sources earthquake volcano and submarine mass failure we therefore suggest that a seismically triggered submarine mass failure on the upper portion of the continental slope offshore from southwestern taiwan is the most likely source of the eighteenth century event

correlation of middle devonian hamilton group equivalent strata in east central north america implications for eustasy tectonics and faunal provinciality

measuring ocean wave period with satellite altimeters a simple empirical model a simple empirical model is proposed to retrieve wave period from ku band radar altimeter backscatter and significant wave height the model formulation is heuristic and fitted using a large dataset of collocated topex altimeter and buoys measurements empirical models are proposed for the zero up crossing the mean and the peak wave period and compared with models by davies et al 1997 and hwang et al 1998 their performance is assessed using an independent validation dataset and gives a retrieval error of 0 8s regional analysis indicates that the wave period models perform better in wind seas than in swell dominated conditions